WO2016050605A2

WO2016050605A2 - Method for growing semiconductor layers and support for growing semiconductor layers

Info

Publication number: WO2016050605A2
Application number: PCT/EP2015/071996
Authority: WO
Inventors: Alexander Behres; Hans-Jürgen LUGAUER; Jürgen Moosburger; Thomas Bleicher; Harald Laux; Matthias Sabathil
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2014-09-30
Filing date: 2015-09-24
Publication date: 2016-04-07
Also published as: DE102014114220A1; WO2016050605A3

Abstract

Disclosed is a method for growing semiconductor layers. In a step A, a support (1) is provided. In a step B, at least one substrate (2) is placed onto the support (1). Then in a step C, a growing process is carried out in which a semiconductor layer sequence (20) is grown on a main side of the substrate (2) facing away from the support (1). The fully grown semiconductor layer sequence (20) emits electromagnetic radiation during the intended operation. In an additional step D, a temperature-measuring process is carried out in which a temperature profile (3) of the substrate (2) which is present in the substrate (2) during the growing process is determined. Additionally, a step E is carried out in which the support (1) and/or the substrate (2) are processed in a controlled manner prior to or during the growing process. As a result, the temperature in selected regions of the substrate (2) is changed and an emissions profile of the fully grown semiconductor layer sequence (20) is leveled out.

Description

description

Process for growing semiconductor layers and substrates for growing semiconductor layers

It will be a process for growing up

Semiconductor layers specified. In addition, a support for the growth of semiconductor layers is given. An object to be solved is to provide a method for growing semiconductor layers, in which

Inhomogeneities in the material composition and the

Material structure of the semiconductor layers can be reduced. Another object to be solved is to provide a carrier with which such growth is possible.

These objects are achieved by the method and subject matter of the independent claims. advantageous

Embodiments and developments are the subject of the dependent claims.

In accordance with at least one embodiment, the method for the growth of semiconductor layers comprises a step A, in which a carrier is provided. The carrier is in particular a substrate carrier on which

Growth substrates for semiconductor layers are preferred

reversibly mounted and / or can be attached. For this purpose, the support has, for example, support structures which prevent slippage of the substrates during the process

Prevent the growth process.

In particular, the carrier has a high thermal conductivity, for example of at least 50 W / (mK) or 100 W / (mK) or 150 W / (mK). For this purpose, the carrier comprises, for example, a silicon carbide, such as SiC, or a coated graphite, for example a graphite coated with SiC, or consists thereof. Further, the carrier is, for example, in the form of a circular disc having at least one main side

formed and has, for example, a diameter along the main side of at least 10 cm or at least 30 cm or at least 50 cm. In accordance with at least one embodiment, in a step B, one or more substrates are applied to the carrier. The substrate is in particular a

Growth substrate for, for example, semiconductor layers. The substrate may in particular comprise or consist of one or more of the following materials: Si, GaAs, GaN, GaP, sapphire, SiC, AlN.

The substrate is, for example, as a disk, in particular a circular disk, with at least one main side

educated. The diameter along the main side is, for example, at least 5 cm or> 10 cm or> 15 cm.

Alternatively or additionally, the diameter of the substrate -S is 30 cm or <20 cm or <10 cm. After step B

The main side of the substrate preferably runs parallel or approximately parallel to the main side of the carrier.

In accordance with at least one embodiment, a growth process is performed in a step C. In the growth process, a semiconductor layer sequence is preferably grown on a main side of the substrate facing away from the carrier.

During the growth process, the substrate is thus located between the carrier and the semiconductor layer sequence grown on the substrate. In particular, it may be at the on the substrate grown semiconductor layer sequence to act semiconductor layers on GaN or GaAs or GaP or Si base. After the growth process, the finally grown semiconductor layer sequence is set up, for example, to emit electromagnetic radiation, for example visible radiation, during normal operation. In particular, individual light-emitting semiconductor components, such as LEDs, can be produced from the finished semiconductor layer sequence.

For example, during the growth process, the carrier is disposed in a reaction chamber. The one described here

Method is particularly suitable for processes in which the semiconductor layers in a chemical vapor deposition, such as an organometallic chemical vapor deposition, short MOCVD, are applied. It is also possible to grow the semiconductor layers by means of molecular beam epitaxy or by means of a sputtering process. Preferably, the semiconductor layer sequence is applied over the entire surface of the main side of the substrate, so that at least 90% or> 95% or> 98% of the main side of the substrate are covered with the semiconductor layer sequence. The thickness of the resulting semiconductor layer sequence is preferably low compared to the thickness of the growth substrate.

By way of example, the thickness of the semiconductor layer sequence after completion of the growth process is at most 20 μm or at most 10 μm. The thickness of the substrate may be against

^ 100 ym, in particular ^ 200 ym be.

In accordance with at least one embodiment, a temperature measurement process is performed in a step D. In which

Temperature measuring process is preferably a temperature profile of the Substrate determines which occurs in the substrate during the growth process. The temperature profile is preferably determined as a location-dependent temperature distribution along the main side of the substrate. In particular, that is

Temperature profile thus a three-dimensional function or a three-dimensional histogram, in which the temperature of the substrate is indicated as a function of x and y, where x and y are the location coordinates along the main side of the substrate.

Here and below, for example, the temperature of the substrate is the average temperature over the entire

Thickness, ie expansion in the z direction, of the substrate or the surface temperature on the side facing away from the carrier

Main side of the substrate or the temperature of the

grown semiconductor layer sequence or the emerging semiconductor layer sequence

Understood. Since the substrate is preferably substantially thicker than the semiconductor layer sequence, the temperature of the semiconductor layer sequence and the substrate are almost identical.

In accordance with at least one embodiment, a targeted processing of the carrier and / or the substrate is carried out in a step E. The processing can be permanent or reversible. Reversible here means that changes made to the substrate or to the carrier can later be reversed without destroying or damaging or deforming the substrate or the carrier. It is also conceivable that the changes will disappear or disappear over time. Permanent means to

Example, that by the processing on the carrier

caused change can not be undone or can be made. Under a targeted processing is here understood that the processing of the carrier and the substrate happens intentionally and controlled.

For example, the carrier or the substrate is processed or changed only locally in deliberately selected areas.

Preferably, the temperature is changed in selected areas along the main side of the substrate during the growth process, in particular controlled by the targeted and reversible processing of the carrier. This means, for example, that in this area the temperature is around

predetermined values can be increased or decreased. The processing can take place before or during the growth process. Preference is given by this processing

Emission profile of the finished grown

Smoothed semiconductor layer sequence.

Under the emission profile is in particular the emitted by electroluminescence or photoluminescence

Wavelength spectrum of the finished grown

Semiconductor layer sequence understood as a function of the location along a main radiation side of the semiconductor layer sequence. The main radiation side is preferably in

Substantially parallel to the main side of the substrate.

For example, on the main radiation side a

Most of the generated by the semiconductor layer sequence

Radiation decoupled. In particular, the emission profile is thus a three-dimensional function or a

Three-dimensional histogram, in which the emission spectrum of the semiconductor layer sequence as a function of x and y

where x and y are the location coordinates along the main radiation side of the semiconductor layer sequence. The smoothing of the emission profile thus has the consequence that the Semiconductor layer sequence along the entire

Main radiation side has a homogeneous, ie substantially the same, emission spectrum. For example, by processing the carrier or the substrate, the temperature profile determined in step D can be smoothed, thereby smoothing the

Emissions profile can be achieved. Temperature variations along the main side of the substrate can then be compensated by the machining, so that especially after processing in all areas along the main side of the substrate only small temperature fluctuations, such as temperature fluctuations of less than 5 K or less than 1 K or less than 0.5 K. occur. Alternatively, the temperatures of the temperature profile after processing may also vary at most 1% or at most 0.5% or at most 0.1% by a maximum temperature of the temperature profile.

However, it is also possible that inhomogeneities are introduced into the temperature profile by the machining. With these temperature inhomogeneities, other effects in the growth of the semiconductor layer sequence, which lead to inhomogeneities in the emission profile, will compensate for the production of a

Semiconductor layer sequence is achieved with a smoother emission profile.

In accordance with at least one embodiment, steps A to E are performed in the order indicated.

In at least one embodiment, the method for growing semiconductor layers comprises a step A of providing a carrier. In a step B becomes at least one substrate applied to the carrier. Furthermore, in a step C, a growth process is carried out, in which a semiconductor layer sequence is applied to the carrier

grown away from the main side of the substrate. The finally grown semiconductor layer sequence emits electromagnetic radiation during normal operation. In a further step D, a temperature measuring process is carried out in which a temperature profile of the substrate, which during the growth process in the substrate

occurs, is determined. In addition, a step E is carried out, in which the carrier and / or the substrate are specifically processed before or during the growth process.

As a result, the temperature is changed in selected regions of the substrate and the emission profile of the finished grown semiconductor layer sequence is smoothed.

The invention described herein is based inter alia on the finding that the wavelength of light-emitting LEDs, such as InGaN LEDs, essentially by the temperature of the semiconductor layers during the growth process

is determined. For example, shifts in

common LEDs with an increase in the

Growth temperature of 1 K, the wavelength of the LEDs produced by 0.5 nm to 2 nm. In the growth process of

Semiconductor layers on a growth substrate give way to the temperature profile along the main side of the substrate

due to a variety of factors, such as the distance of the wafer from the carrier, the local thermal conductivity of the gas mixture between carrier and substrate, the emissivity of the carrier, the cooling of the process gases used or the geometric features at the substrate edge, of an ideal homogeneous temperature profile from. Such a temperature inhomogeneity and the so However, connected inhomogeneity in the light emission or emission profile may have great potential

Effects on the yield of LED chips and logistics in LED manufacturing. For example, the LED chips fabricated on the edge of the substrate may be due to there

occurring large temperature shift can not be sold.

Among other things, the invention described here makes use of the idea of changing the support or the substrate during the growth process over reversed or permanent machining processes in such a way that it leads to a

Homogenization or smoothing of the

Emission profile of the finished grown

Semiconductor layer sequence comes. This is done, for example, by smoothing out the wax

Temperature profile achieved. Compared with usual

Growth processes thereby enable a more homogeneous growth of the semiconductor layer sequence with fewer fluctuations in the material composition and material structure along the entire main side of the substrate. The resulting in production of waste on LED chips can be reduced. In accordance with at least one embodiment, in step E, during the growth process, a laser beam from a laser is directed onto the substrate, in particular onto the main side of the substrate facing away from the carrier. With the laser beam then selected, so deliberately determined areas of the substrate, heated specifically. In this case, the regions of the substrate which in the temperature profile form cooler areas of the substrate are preferably heated. Alternatively or

In addition, in step E, not the substrate, but the Carrier heated by means of the laser beam in selectively selected areas. The laser beam may also be directed to an upper side of the carrier facing the substrate or an underside of the carrier opposite to the upper side, the upper side and the lower side respectively

Make homepages of the vehicle. The heat generated by the laser beam in areas of the carrier then transmits to corresponding, for example, adjacent or

opposite, areas of the substrate. It is also possible, for example, by means of one on top

directed laser, such as a UV laser, that the

Laser radiation directly in the semiconductor layer sequence

is absorbed and thus the semiconductor layer sequence is heated directly.

In accordance with at least one embodiment, the laser beam is activated in operation during the growth process by means of a

Scanning targeted to selected areas of the substrate. The scanning unit can move the laser beam over the main side of the substrate or the carrier, in particular at a constant speed, for example at least 20 m / s or at least 40 m / s or at least 80 m / s. In this case, it is advantageous if the intensity and / or the power of the laser radiation are modulated. If the laser beam is aimed at a region that is to be heated, the power and / or the intensity are increased. In areas that are not to be heated, power and / or intensity are reduced. Alternatively, however, it is also possible that the laser beam has a temporally constant power and / or intensity

having. The scanning unit then preferably moves the laser beam abruptly over the main side of the substrate or of the carrier. How strong the substrate in the selected

Is then heated over the areas

Irradiation time regulated in the respective area. Preferably, the scanning unit is arranged so that the laser beam can be directed to all areas of the main side of the substrate or carrier. This can be the

Scanning unit align the laser beam, for example, two-dimensional. In particular, the scanning unit can

Laser beam independently along two base vectors, which span the main side of the substrate or the carrier to move.

In accordance with at least one embodiment, during the growth process, the carrier is rotated about an axis of rotation perpendicular to the main side of the carrier. The scanning unit can then move the laser beam during the growth process, for example in a radial direction, perpendicular to the axis of rotation. A one-dimensional movement along a straight line may be sufficient. At each rotation is in

Top view of the main side of the carrier one of the

Laser beam swept line on the main page of the

Carrier completely crossed by the substrate, so that all areas of the substrate can be selectively heated by means of the laser beam. Again, it is possible that the laser beam at a constant speed along the radial direction is moved or jumped

is aligned. In accordance with at least one embodiment, a plurality of laser beams are along a radial, perpendicular to

Arranged axis of rotation extending direction. The

Laser beams are preferably so close to each other arranged that the projection of the laser beams on the main side of the substrate or the carrier forms a continuous line without interruptions on the main page. This can be done for example by a bar laser

realize. In a plan view of the main side of the carrier, the substrate then preferably crosses over this line completely with each rotation of the carrier, so that each region of the substrate can cross one of the laser beams and thereby be heated in a targeted manner. In the embodiment described here, the laser beams need not have a

Scanning unit to be moved. In this case, it is particularly advantageous if the power and / or the intensity of each individual laser beam are modulated. When the substrate is crossed by the laser beams, it is possible to influence in a targeted manner which region on the substrate is stronger and which is heated less strongly.

According to at least one embodiment is in

Temperature measuring process of step D determines the temperature profile of the substrate during the growth process. For example, one or more of the following measuring equipment is used for the temperature measurement process: thermocouple, emissivity-corrected pyrometer, thermal imager,

Infrared diode. The emissivity corrected pyrometer can be used, for example, when the carrier is rotated rapidly with the substrate during the growth process. For example, a thermal imager is useful when the wearer is slow or does not rotate at all. Become

Used infrared diodes, it is advantageous to use a whole series of infrared diodes, for example, with each revolution of the carrier, the entire main side of the

Scan the substrate or support to determine the temperature of the substrate or support. The spatial resolution of the temperature measuring process is preferably better than 10 mm or better than 5 mm or better than 1 mm. Alternatively or additionally, the spatial resolution of

Temperature measuring process 0.5 mm or> 1 mm or> 3 mm.

The temperature measuring processes can be carried out, for example, at a rate of> 1 Hz or> 100 Hz or> 10 kHz. That is, for the determination of the temperature in an area or for determining the entire temperature profile with the above spatial resolution, at most 1 s or at most 1/100 s or at most 1-10 ^-4 s is needed.

In accordance with at least one embodiment, the

Temperature measuring process only after the growing process

carried out. This can be waited, for example, until the substrate with the applied

Semiconductor layer sequence is cooled to room temperature. Then, for example, then a spatially resolved

Wavelength measurement of the photoluminescence spectrum of the

Semiconductor layer sequence performed. Spatially resolved in this context means that those of the

Semiconductor layer sequence emitted wavelength as a function of the location on the main side of the substrate, for example as a function of an x-y coordinate, is measured. With the help of the recorded photoluminescence spectrum can also after

Cooling of the substrate and / or the semiconductor layer sequence on the existing during the Aufwachsprozesses

Temperature profile are inferred. In accordance with at least one embodiment, a control unit is used. The control unit is in particular

set up based on measurements of the

Temperature measuring process the scanning unit and / or the Laser power of the laser and / or the intensity of the laser

Laser radiation and / or the pulse duration of the laser beam and / or to control the diameter of the laser beam. Such a control unit allows, for example, the areas of the substrate which are to be heated for smoothing the temperature profile by means of the laser radiation

determine, drive and adjust the energy transferred to these areas from the laser radiation. In accordance with at least one embodiment, the

Temperature measuring process during the growing process of

Semiconductor layer sequence performed several times. In particular, multiple means that a temperature measurement over the entire substrate at the latest after every second or

at the latest after every tenth second or at the latest after every minute. On the other hand, it is also possible that the temperature profile of the substrate is recorded continuously during the growth process. Preferably, the control unit is then operated so that the control unit after each temperature measurement process the

Scanning unit and / or the laser power of the laser and / or the pulse duration of the laser beam and / or the diameter of the laser beam readjusted, so that the temperature profile

is smoothed. So can also time varying

Temperature profiles are compensated. Will the

Temperature measurement carried out continuously, the readjustment via the control unit can also be carried out continuously. In accordance with at least one embodiment, the laser beam has a power of at least 5 kW or at least 10 kW or at least 20 kW. Such a laser beam can be used both in continuous mode and in modulated mode operate. The laser beam is then used in particular not only for smoothing the temperature profile of the substrate occurring during the growth process, but for the entire heating of the substrate during the growth process. An additional heat source that the

Heated substrate and allows growth of the semiconductor layers is not necessary in this case and / or not used. Typical temperatures to which a substrate for the growth of semiconductor layers must be brought are in the range between 1000 K and 2000 K. By the

Using a laser with a power in the kW range, such a temperature can be achieved even without external heat source. In accordance with at least one embodiment, during the growth process, the substrate is heated in addition to the laser via an additional heat source. The heat source can for

Example, be arranged on the side facing away from the substrate underside of the carrier and during the growing up the

Heat carrier. Heat transfer and heat radiation, for example, transfers the heat from the heat source to the support and then to the substrate, bringing the substrate to a temperature required for growth. In the case of such an additional heat source, for example, it is sufficient if the laser has a power of

at least 100W or at least 200W or at least 500W. Alternatively or additionally, the power of the laser <2000 W or <1000 W or <500 W. The laser beam is then preferably predominantly for smoothing the

Emission profiles or temperature profiles used and not to fully heat the substrate. A laser beam with such a power can, for example Temperature increases in selected areas of the substrate of up to 10 K or up to 20 K or up to

Achieve 30K. According to at least one embodiment, the laser is an infrared laser such as a Nd: YAG or a C02 ^_ uses laser. Also, the use of a green laser, such as a frequency doubled Nd: YAG laser or a

frequency doubled Nd: YLF laser is possible. Also, lasers in the blue or UV range can be used. Suitable lasers are, in particular, dye lasers or semiconductor lasers or fiber lasers, such as semiconductor-pumped fiber lasers, or discrete diode lasers. According to at least one embodiment, the

Semiconductor layer sequence transparent to the laser radiation emitted by the laser, that is at least 90% or 95% or 99% of the semiconductor layer sequence

the incident intensity of the laser radiation passes through the semiconductor layer sequence to the substrate. Advantageously, in this way damage to the

Semiconductor layer sequence avoided by the laser. The

Heating of the semiconductor layers thus takes place preferably indirectly via the substrate. To heat the substrate, the laser may be focused in areas outside or inside the substrate. In particular, the laser power and the laser focusing are adjusted so that it during the

Growing process does not cause damage to the substrate, which, when growing up, leads to defects in the substrate

Lead semiconductor layer sequence.

It is also conceivable here that the substrate and / or the carrier are also transparent in the above sense. To heat the Substrate with the aid of the laser can then on the underside of the carrier and / or substrate, for example a

Absorption layer may be attached, for example, a metal, which absorbs at least a part, in particular a majority, of the laser radiation impinging on them. Will the

Heating layer adsorbed, the resulting heat can be transferred to the semiconductor layer sequence.

According to at least one embodiment, the on the

Substrate projected laser beam has a diameter of at least 0.5 mm or at least 1 mm or at least 3 mm. Alternatively or additionally, the diameter of the

Laser beam on the substrate -S 10 mm or <5 mm or

<1 mm.

The substrate and / or carrier has for example one

Thermal conductivity of> 1.5 W / (m-K) or> 5 W / (m-K) or ^ 10 W / (m-K). Alternatively or additionally, the

Thermal conductivity of the substrate ^ 200 W / (m-K) or

<100 W / (m-K) or <80 W / (m-K). By choosing one

suitable, preferably low, thermal conductivity of

Substrate and / or support, can be achieved that heated by the irradiation with the laser beam

Areas on the substrate and / or support over the

Diameter of the laser beam can be defined, which allows a locally targeted heating of the substrate and / or support with a sharply-defined local demarcation.

According to at least one embodiment, in the method for growing semiconductor layers, the

Temperature measuring process performed in step D before the waxing process in step C. The temperature measurement process becomes the Example determined during a previous growth process.

In accordance with at least one embodiment, in step B, the substrate is preferably applied to the carrier in such a way that a cavity occurs between the substrate and the carrier. This cavity is for example during the subsequent

Growth process in step C partially or completely filled with a gas.

Furthermore, before the step C, preferably also before the step B, in the region of the cavity between the carrier and the

Substrate a coating applied locally to the carrier. In particular, the coating fills the case

However, cavity is not completely out, that is, during the growth process in step C, the coating is spaced from the support, for example, by the cavity. The

Coating, for example, is designed to be

at any time, for example after the growth process in step C, can be partially or completely removed from the carrier and can be replaced, for example, by a new coating. It can not do the coating either

be removable and remain permanently on the carrier. In cross-sectional view, in a section through the substrate or the support perpendicular to the respective main sides, the cavity has, for example, a rectangular

Cross-sectional shape. The cavity preferably extends along the entire or almost entire lateral extent of the substrate and is arranged between parallel or nearly parallel main sides of the substrate and the carrier. The lateral extent is the extent parallel to the main sides. The thickness of the Cavity, so the distance between substrate and carrier is on average, for example, at least 0.05 mm or> 0.1 mm or> 1 mm. Alternatively or additionally, the mean distance -S 2 mm or <1.5 mm <1 mm.

In accordance with at least one embodiment, the coating has a different emissivity than the carrier, in particular a different emissivity than an upper side of the carrier facing the substrate. In this case, the coating is preferably selected so that the measured in step D.

Temperature profile of the substrate during the growth process in step C is smoothed. In particular, the

Coating a smaller emissivity than the carrier or as the surface of the carrier.

During the growth process, areas are created between the substrate and the substrate, via the heat from the substrate

can be directed particularly efficiently to the substrate. If, for example, the carrier is heated from an underside, it can lead to increased thermal conductivity in the region of contact points on which the substrate rests on the carrier. In these areas, the substrate is heated more than in areas where the thermal conductivity is reduced. This can result in an inhomogeneous temperature profile along the main side of the substrate. Is applied in the areas of increased thermal conductivity between the support and substrate, a coating whose emissivity to

Example is smaller than that of the carrier, the emitted from these areas during the growing process

Thermal radiation reduced. The reduced heat radiation can then partially or completely compensate for the increased thermal conductivity in these areas, causing the Temperature variations along the main side of the substrate can be smoothed.

In accordance with at least one embodiment, the coating is applied gradually to the carrier, so that a

Surface coverage density of the coating on the carrier varies along the major side of the carrier. In areas of the wearer, the warmer according to the temperature measuring process

Corresponding areas on the substrate, the

Coating for example with a higher one

Surface coverage density applied, in areas corresponding to cooler areas of the substrate, the surface exposure density of the coating is then set lower, for example. The area occupation density of the

Coating on the carrier then decreases from warmer

Regions of the substrate to colder areas of the substrate.

Corresponding regions between carrier and substrate are, for example, regions which lie directly opposite one another, that is, between which the distance between carrier and substrate is the smallest.

The coating does not have to be gradual. It can also be a continuous,

contiguous and unstructured layer, such as an annular layer.

According to at least one embodiment, the coating comprises or consists of one of the following materials:

Molybdenum, chromium-free steel, tungsten, ceramics, titanium. The coating is in this case, for example, with a layer thickness of at least 0.2 ym or at least 1 ym or at least 3 ym applied. Alternatively or additionally, the

Layer thickness -S 50 ym or <20 ym or <10 ym. Of the

Emissivity of the coating is preferably at most 0.7 or at most 0.4 or at most 0.2.

In particular, the emissivity of the coating preferably deviates by at least 0.2 or at least 0.4 or

at least 0.9 from the emissivity of the carrier.

Alternatively or additionally, analogous to the above

described embodiment, the coating can also be applied to a carrier-facing underside of the substrate. For example, then the different

Reflectance or degree of absorption of the coating for thermal radiation from the reflectance or absorptance of the substrate. In areas of elevated temperature in the measured temperature profile can then, for example, a higher

Reflectance or lower degree of absorption can be set as in cooler areas, which can also lead to a smoothing of the temperature profile.

In addition, a carrier for growing up

Semiconductor layers specified. The carrier can be used for the method described above. Features of the method described above are therefore also disclosed for the wearer and vice versa.

In accordance with at least one embodiment, the substrate for growing semiconductor layers comprises a recess into which a substrate is introduced during the intended growth of semiconductor layers. The recesses serve for example for mechanical fixation and stabilization of the substrate during the growth process. For example, the recess is designed so that when inserting the Substrate in the recess, the substrate flush with the

Completing top of the vehicle. It is also possible that the substrate is completely embedded in the recess during the growth process. About closure devices on the carrier, the substrate may be secured during growth against detachment from the recess. One

Removal of the substrate after growth then takes place, for example, via a pick-and-place method. The coating is carried out, for example, as indicated above for the method.

Alternatively or additionally, however, the coating can also be applied to the underside of the carrier, opposite the recess, wherein the coating, for example, also extends gradually. The coating is then selected, for example, to have a higher reflectance or lower degree of thermal radiation absorption than the support. If the carrier is heated by a heat source on the underside of the carrier, then in the area of

Coat the incident heat radiation stronger

reflected or less absorbed than in the area of the carrier. The regions of the substrate which are opposite to the coating are then heated less strongly by means of the carrier than regions of the substrate which have no

Opposite coating.

Hereinafter, a method for growing semiconductor layers described here and a substrate described here for growing semiconductor layers are described below

Reference to drawings using exemplary embodiments explained in more detail. The same reference numerals indicate the same elements in the individual figures. There are, however no scale relationships shown, but individual elements may be exaggerated to better understand.

Show it:

Figures 1 to 4 different process steps of a

method described here in side view of the process device,

FIG. 5 shows a method step of one described here

Process in plan view of the

Process device

Figures 6 and 9 simulation results for here

described method,

Figures 7 and 8 embodiments of one here

described support for the process device in side view and top view.

FIG. 1 shows a side view of a device which, for example, is used for the growth of semiconductor layers in organometallic chemical vapor deposition, in short

MOCVD, is used. The device comprises a carrier 1 with an upper side and one of the upper side

opposite bottom and is formed for example from Sic. In the top of the carrier 1 recesses 12 are inserted, extending from the top in the direction

Extend bottom, the carrier 1 but not break. The carrier 1 is formed axially symmetrical to a rotation axis 10, wherein here on both sides of the rotation axis 10 each two of the recesses 12 are introduced into the carrier 1 are. In each of the recesses 12 of the carrier 1, a substrate 2 is introduced, which in the present case serves as a growth substrate and is formed, for example, from GaN or sapphire or silicon. The substrates 2 are within the

Recesses 12 on support points 13. The support points 13 are preferably chosen small, their lateral

Expansion along the main side of the carrier is for example at most 5% of the lateral extent of the

Recesses 12. In Figure 1, between the substrate 2 and the carrier 1 in the region of the recesses 12 each one

Cavity 14 is formed, which is filled for example with a process gas.

FIG. 1 shows a step C of the method, in which a semiconductor layer sequence 20 is respectively grown on the main sides of the substrates 2 facing away from the carrier 1. For a uniform growth of the semiconductor layer sequence 20, the carrier in FIG. 1 is rotated about a rotation axis 10. The rotation speed is thereby

for example, between 30 and 2000 revolutions per minute. Due to the rotation and the associated

Centrifugal force on the substrates 2, the substrates 2 are partially displaced and durchbogen, so that in the central region of the substrates 2, between the support points 13, the distance to the carrier 1 is reduced. However, the sag can also arise at least in part because of tension in the substrate during a growth process. In this case, the substrate bends, for example, between 50 ym and 200 ym.

FIG. 1 also shows that the device for growing semiconductor layers has a heating element 6 which is mounted on the underside of the carrier 1. By the Rotation of the carrier 1 about the axis of rotation 10, the carrier 1 during the growth process is preferably

heated evenly. FIG. 1 also simultaneously shows a method step D, in which a temperature measuring process is carried out. For the temperature measuring process, a temperature measuring device 8 is mounted on the top of the carrier 1. The

Temperature measuring device 8 is spaced from the carrier 1 and the substrates 2 and measures a temperature profile 3 along main sides of the substrates 2. For this purpose, the temperature measuring device 8 comprises, for example, one or more emission degree-corrected pyrometer, the temperature on the main sides of the substrates 2 with a Measure spatial resolution of <3 mm.

The temperature measuring device 8 is connected in the example of Figure 1 to a control unit 7, wherein the

Control unit 7 in turn with a laser 4 and a

Scanning unit 5, which is presently designed as a mirror, is connected. In the example of FIG. 1, the laser 4 is initially out of operation.

A cut through a through the temperature measurement process

specific temperature profile 3 of the substrates 2 is

shown by way of example in FIG. FIG. 2 shows a diagram with the temperature T on the y-axis and the radius r

or the distance r from the axis of rotation on the x-axis. It can be seen that the temperature profile 3 in the region of the support points 13 and in the central region of the substrates 2 has elevated temperatures T. Between the central region and the support points 13 are

To detect temperature minima. The elevated temperature T in middle region between the support points results from the bending of the substrates 2 shown in FIG. 1. The reduced distance in these middle regions enables improved thermal conductivity via the process gas located in the cavity 14.

FIG. 3 shows a method step E which, for example, follows the temperature measuring process of step D of FIGS. 1 and 2. The device shown in Figure 3 corresponds to the device in Figure 1. The carrier 1 is further rotated about the axis of rotation 10, the

Semiconductor layer sequence 20 is further grown on the substrates 2. In contrast to FIG. 1, FIG. 3 shows that the laser 4 is operated. The laser 4 is, for example, an Nd: YAG laser that projects infrared laser radiation 40 onto the scanning unit 5. The scanning unit 5 is presently designed as a mirror, wherein the mirror is connected for example to a motor. Of the

Adjustment angle of the mirror can be varied by the motor. The mirror reflects on him

Laser beam 40 in the direction of the carrier 1 and is directed to selected areas of the substrate 2. As a result of the irradiation of the selected area of the substrate 2 with the laser radiation 40, this selected area is locally heated in a targeted manner. The scanning unit 5 may, for example, the laser beam 40 one-dimensional along the radial

Move direction r. Due to the additional rotation of the carrier while all areas of the substrates 2 with the

Laser beam 40 are irradiated and selected areas on the substrates 2 can be selectively heated. Alternatively, in the device in FIG. 3, the radiator 6 shown there may also be dispensed with. This is

Especially possible if the laser 4 has a sufficiently high power, for example, at least 5 kW to alone by the irradiation of the laser radiation 40 on the

Substrate 2 to set a necessary growth temperature of the substrates 2.

FIG. 4, like FIG. 2, shows a section through a possible temperature profile 3 of the substrates 2. However, the temperature profile 3 is shown here after the laser beam 40 has heated certain areas on the substrates 2.

It is evident from FIG. 4 that the laser beam 40 causes the temperature profile 3 of FIG. 4 to be opposite that of FIG

Temperature profile 3 of Figure 2 is smoothed or homogenized. The temperature fluctuations on the substrate 2 are thus reduced along the main side of the substrates 2.

In FIG. 5, that shown in FIGS. 1 and 3 is shown

Device in a plan view of the main side of

Substrates 2 and on the top of the carrier 1 shown. Unlike in FIGS. 1 and 3, FIG. 5, however, does not use a single laser whose laser radiation 40 is directed onto the substrates 2 via a scanning unit 5, but rather a laser diode array, for example in the form of a laser bar, in FIG arranged the carrier 1. In the laser diode array, a plurality of lasers 4 are arranged in series next to one another. The radiation 40 emitted by the lasers 4, when projected onto the carrier 1, forms a continuous line which, for example, extends from the axis of rotation 10 to the outer edge of the carrier 1. By the

Rotation of the carrier 1 is achieved in that each

Area on the substrates 2 at least one laser beam 40th thwarted. By modulation of the laser power emitted by the lasers 4 and / or load intensity, targeted heating of specific areas on the individual substrates 2 can then be achieved.

Figure 6 shows results for a method as described in connection with Figures 1 to 5. In this case, a carrier 1 was rotated at different rotational speeds Ω. The rotational speeds are listed in units of revolutions per minute in the first column of the table. In addition, for each rotation speed, the revolution time of the carrier τ in seconds is in the second

Column of the table. Furthermore, the

Laser intensities varies. The third column of the table shows laser intensities P from 0.1 kW to 1 kW. The right column of the table gives the diameter d of

Laser radiation 40 in centimeters.

The graphs on the right side of FIG. 6 show the results using the ones shown in the table

Parameter. The procedure was as follows: A specific area on the substrate 2 was briefly heated when passing through a laser beam 40. This brief heating up can be seen in the graphs as the rapid increase in temperature by ΔΤ in the range t ~ 0 s. Subsequently, the heated area has left the laser beam 40 and then, as seen in the graph, cooled as a function of time. The graphs end at 0.05 and 0.06 seconds respectively, which corresponds to the circulation times of the carrier 1 from the table. After this circulation time, the heated area would again laser beam 40th

thwart and reheat. As can be seen from the graphs of FIG. 6, after one complete revolution of the carrier 1, the heated region does not cool down again to its starting temperature. This shows that if the area on the substrate 2 is heated several times, the irradiated area is permanently elevated

Temperature can be maintained.

The difference between the upper image and the lower image on the right side in FIG. 6 is that, for the acquisition of the graphs in the upper image, the carrier 1 was heated by means of the laser 4, which leads to an indirect heating of the substrate 2. By contrast, the graphs in the lower image were recorded on laser irradiation of the substrate 2, ie the substrate 2 was heated directly and not via the support 1.

FIG. 7 shows a side view of a carrier 1 as described in connection with FIGS. 1 and 3. in the

In contrast to FIGS. 1 and 3, a coating 11 is applied in FIG. 7 on the side of the carrier 1 facing the substrate 2 in the region of the recess 12. The

Coating 11 is applied gradually, so that a surface occupation density varies along the main side of the substrate 2. In the present example, the

Surface occupation density of the coating 11 in the region of

Support points 13 and in the central region, in which the distance between the substrate 2 and the carrier 1 is reduced increases.

In the present case, the coating 11 is made, for example

formed chromium-free steel and has a smaller by at least 0.6 emissivity than the carrier 1.

The gradually applied coating 11 with the smaller emissivity has the following technical effect. in the Area of support points 13 and in the central region of the recess 12 takes place between the carrier 1 and the substrate 2, an increased heat conduction. This creates

Temperature variations along the main side of the support 2, resulting in, for example, as shown in Figure 2 temperature profile 3 of the substrates 2. To this

Smoothing temperature profile 3 during the growth process is the gradual coating 11 on the carrier 1

applied. In the area of a high surface occupation density of the coating 11 there is a lower emission of

Thermal radiation in the direction of substrate 2 instead of in areas with lower surface occupation density. This reduced emission of heat radiation can then partially or completely compensate for the effect of the increased heat conduction and thus to a smoothing of the temperature profile 3 during the

Growth process or for smoothing the

Emission profiles, as it is for example in

Related to Figure 3 is shown. In the embodiment of Figure 8, the carrier 1 with the recess 12 and the gradually applied coating 11 in plan view of the main side of the carrier 1 is shown.

In the present case, for example, the coating 11 covers at least 1% or 5% or 10% of the carrier 1 in the region of

Recess 12.

FIG. 9 shows results obtained by means of a method as described in connection with FIGS. 7 and 8

Coating 11 can be achieved. The graph on the right side shows a temperature profile 3 of the substrate 2 as the distance r from the axis of rotation of the carrier. The

black curve shows the results, if none

Coating 11 is used. These results Corresponding to the table entry "std", as a short form for standard Due to the bending of the substrate, at temperatures of r = 0 mm, temperatures T are higher in the center of the wafer than at r ~ 75 mm in the outer area of the wafer 11 applied, whose

Surface coverage density in the central region of the substrate 2 is greater than in the outer region of the substrate 2 and this coating 11 has a smaller emissivity than the carrier 1, the temperature in the center of the substrate 2 during the growth process can be reduced, whereby the more homogeneous, in gray shown temperature distribution is generated. In the present case, the emissivity of the carrier 1 was chosen to be 0.8, the emissivity of the coating 11 was selected to be 0.2. The corresponding table entry is marked with "vi".

The invention described here is not by the

Description limited to the embodiments.

Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly listed in the claims or exemplary embodiments.

This patent application claims the priority of German Patent Application 10 2014 114 220.9, the disclosure of which is hereby incorporated by reference. Reference sign list

1 carrier

2 substrate

3 temperature profile

4 lasers

5 mirrors

6 radiators

7 control unit

8 temperature measuring device

10 rotation axis

11 coating

12 recess

13 point of support

14 cavity

20 semiconductor layer sequence

40 laser beam

Claims

claims

Method for growing semiconductor layers comprising the steps:

A) providing a carrier (1);

B) applying at least one substrate (2) to the carrier (1);

C) carrying out a growth process, in which a semiconductor layer sequence (20) on a the carrier (1) facing away from the main side of the substrate (2) is grown, wherein the grown grown

Semiconductor layer sequence (20) emitted in the normal operation of electromagnetic radiation;

D) carrying out a temperature measuring process in which a temperature profile (3) of the substrate (2) which occurs in the substrate (2) during the growth process is determined;

E) targeted processing of the support (1) and / or the substrate (2) before or during the growth process, whereby the temperature in selected areas of the substrate (2) is changed during the growth process and thus an emission profile of the finished

grown semiconductor layer sequence (20) is smoothed.

A method of growing semiconductor layers according to claim 1, wherein

In step E) selected areas during the growth process, the substrate (2) by means of at least one laser beam (40) of at least one laser (4) are selectively heated. A method of growing semiconductor layers according to claim 2, wherein

the carrier (1) is rotated about a rotation axis (10) perpendicular to the main side of the carrier (1) during the growth process,

a series of laser beams (40) along one

radial, perpendicular to the axis of rotation (10)

extending direction is arranged

- With each rotation of the carrier (1) each area of the substrate (2) at least one of the laser beams (40) through.

A method of growing semiconductor layers according to at least claim 2, wherein

- The at least one laser beam (40) has a power of at least 5 kW,

- The laser beam (40) is used to heat the substrate (2), so that no further heating source than the laser (4) is required for the growth process.

A method of growing semiconductor layers according to at least claim 2, wherein

a scanning unit (5) specifically aligns the laser beam (40) with selected regions of the substrate (2) during operation during the growth process.

A method of growing semiconductor layers according to the preceding claim, wherein

the support (1) is rotated about a rotation axis (10) perpendicular to a main side of the support (1) during the growth process,

- The scanning unit (5) the laser beam (40) during the growth process on the substrate (2) in one radial direction, perpendicular to the axis of rotation (10) moves.

Process for the growth of semiconductor layers according to one of the preceding claims, wherein the

Processing of the carrier (1) and / or the substrate (2) is reversible, so that changes that are made during processing on the substrate (2) or on the carrier (1) can be reversed later without the substrate (2) or destroying or damaging the carrier (1).

Process for the growth of semiconductor layers according to at least one of the preceding claims, wherein

in the temperature measuring process of step D)

Temperature profile (3) of the substrate (2) is determined during the growth process,

- wherein for the temperature measuring process one or

several of the following measuring equipment can be used: thermocouple, emissivity corrected pyrometer, thermal imager, infrared diode.

the temperature measuring process is carried out after the growing process,

- The temperature profile (3) of the substrate (2) by spatially resolved wavelength measurement of the

Photoluminescence spectrum of

Semiconductor layer sequence (20) is determined.

10. A method for growing semiconductor layers according to at least claim 5, wherein a control unit (7) is inserted,

- The control unit (7) based on measurements of the

Temperature measuring process, the scanning unit (5) and / or a laser power of the laser (4) and / or a pulse duration of the laser beam (40) and / or the diameter of the laser beam (40) controls.

11. A method for growing semiconductor layers according to the preceding claim, wherein

- The temperature measuring process several times during the

Growth process of the semiconductor layer sequence (20) is performed,

after each temperature measuring process, the control unit (7) the scanning unit (5) and / or the laser power of the laser (4) and / or the pulse duration of the

Laser beam (40) and / or the diameter of the laser beam (40) readjusted, so that the

Emission profile of the finished grown

Semiconductor layer sequence (20) is smoothed.

12. A method for growing semiconductor layers according to at least claim 2, wherein

- the substrate (2) is heated during the growth process next to the laser (4) via an additional heating source (6),

the laser (4) has a power between 100 W and 2000 W,

- The laser beam (40) causes local temperature increases on the substrate (2) of up to 10 K.

13. A method for growing semiconductor layers according to at least claim 2, wherein

- The laser beam (40) in a continuous or operated pulsed mode,

the laser beam (40) has a wavelength in the green or blue or UV spectral range,

- The semiconductor layer sequence (20) is transparent to the laser beam (40), so that over 90% of the semiconductor layer sequence (20) striking the intensity of the laser radiation (40) through the

Semiconductor layer sequence (20) passes.

A method of growing semiconductor layers according to at least claim 2, wherein

a diameter of the laser beam (40) is between 0.5 mm and 10 mm,

the thermal conductivity of the substrate (2) is between 1.5 W / (m-K) and 200 W / (m-K),

- The lateral extent of the heated portion of the substrate (2) by the diameter of the laser beam (40) is defined.

the step D) is carried out before step C),

in step B) the substrate (2) is applied to the carrier (1) such that a cavity (14) occurs between the substrate (2) and carrier (1),

- Before the growth process in step C) in the region of the cavity (14) between the carrier (1) and the

Substrate (2) a coating (11) is applied locally to the carrier (1),

the coating (11) has a different emissivity than the carrier (1),

- The coating (11) is chosen so that the Emission profile of the finished grown

Semiconductor layer sequence (20) is smoothed.

the coating (11) has a smaller emissivity than a surface of the substrate facing the substrate

Carrier (1),

- The coating (11) is applied gradually, so that a surface occupation density of the coating (11) on the support (1) of the

Temperature measuring process certain warmer areas of the substrate (2) decreases to cooler areas of the substrate (2).

A method of growing semiconductor layers according to any one of claims 15 or 16, wherein

the coating (11) comprises or consists of one of the following materials: Mo, chromium-free steel, W, ceramic, titanium,

the coating (11) is applied with a layer thickness of between 1 μm and 1 mm inclusive,

- The emissivity of the coating (11) is at most 0.7.

Support (1) for growing semiconductor layers, comprising

- A recess (12) into which at

intended growth process of

Semiconductor layers a substrate (2) is introduced,

- A gradually extending coating (11) on the support (1) within the recess (12), wherein the Coating (11) has a lower emissivity than the carrier (1).