WO2003015145A1

WO2003015145A1 - Micromachining method using ionbeam

Info

Publication number: WO2003015145A1
Application number: PCT/JP2002/007999
Authority: WO
Inventors: Tadaaki Kaneko; Yasushi Asaoka; Naokatsu Sano
Original assignee: The New Industry Research Organization
Priority date: 2001-08-07
Filing date: 2002-08-06
Publication date: 2003-02-20
Also published as: JP2003051488A; JP4803513B2

Abstract

A micromachining method using an ionbeam, characterized in that it comprises injecting an Ga ion controlled to have a predetermined ion beam diameter and ion current density into the surface of a GaxIn1-xAsyP1-y (0 ≤ x, y ≤ 1) layer, including a GaAs and InP substrate, in a condition wherein an oxide film is formed on its surface or the surface is being irradiated with oxygen molecules, to thereby convert the oxide selectively to Ga2O3 or Ga2O or form the gallium oxide, and then subjecting the surface of the GaxIn1-xAsyP1-y layer to a dry etching on one atomic layer basis by the use of a bromide to remove the above oxide film formed on the surface and the GaxIn1-xAsyP1-y layer which have not converted to Ga2O3 or Ga2O.

Description

Specification

Ion beam fine processing method

The present invention is a compound semiconductor substrate, in particular, G a _x I was market shares epitaxial growth G a A s and I n P substrate - relates sy ion beam microfabrication methods P -y layer surface. Background art

In recent years, with the increase in the integration of ULSI, which is the core of microelectronics, the circuit patterns in these quantum devices are becoming ever smaller. Conventionally, in semiconductor device fabrication processes, semiconductor crystal etching has been widely adopted as a basic technique for removing unnecessary portions of insulating films and metal thin films with high precision according to a resist pattern. As means for this etching method, dry etching using a halogen gas is being studied. Since this dry etching is performed in a relatively clean atmosphere in an ultra-high vacuum, it is expected that a fine quantum device can be processed.

For example, with respect to Si, which is a typical device material, a dry etching process using fluorine and chlorine-based halogen gas has been studied. However, so far, even in the case of silicon, the dry etching process for fabricating finer quantum devices has not yet been completed. Although there are many reports on the dry etching process for compound semiconductors such as 0 a _x I i x x A sy P ^ y including 0 & 3, the technical means that enable the fabrication of quantum devices is still not discussed. As in i, the fact is that it is not completed. For example, GaAs is a material that has a higher electron mobility than Si and can operate at higher frequency and higher speed than Si. In addition, it has developed on an industrial scale in terms of the abundance of resources and the perfection of crystals, and has been replaced by Si as a kind of compound semiconductor that overcomes its limitations. It is the focus of attention. In addition, technologies such as MBE (Molecular Beam Epitaxy) and MOCVD (Metal Organic Chemical Vapor Deposition) have been developed as epitaxy crystal technologies for compound semiconductors such as Ga As, Is becoming possible, and the importance of compound semiconductors as device materials is increasing.

Accordingly, the present inventor has developed a method of dry etching the surface of a semiconductor crystal with a bromide in units of one atomic layer as a dry etching method for overcoming the technical limitations of a conventional dry etching method using halogen gas for compound semiconductors and the like. It is disclosed in Japanese Patent Application Laid-Open No. 8-321483.

However, in order to form a circuit pattern with high accuracy on the surface of the Ga As layer, it was necessary to form a dry etching mask even when dry etching was performed on a single atomic layer basis. In recent years, as circuit patterns in quantum devices have become finer and more complex, it has become difficult to fabricate the dry etching mask itself, and there has been a problem that the reproducibility of the shape and dimensions has been poor.

Moreover, the Ga As layer surface, naturally As _₂ 0 _3, As ₂ 〇, and surface oxide film, such as Ga ₂ 〇 is formed, per to form a mask for dry etching, removing the surface oxide film I also needed to.

The present invention has been made in view of the above problems, G a A G containing _{_{s a x I ni X A s}} yP - on _y layer surface, A s ₂ 0 ₃ which is naturally formed, A s _₂ 0, G a ₂ 0 no need for prior removal of surface Sani匕膜such, also double Without forming a dry etching mask to form a coarse and miniaturized circuit pattern, a fine circuit pattern used for quantum devices can be formed on the surface of the Ga _x _Ini — xA S yP — _y layer. An object of the present invention is to provide an ion beam microfabrication method formed in a field. Disclosure of the invention

The ion beam microfabrication method of the present invention for solving the above-mentioned problem includes a single ion beam diameter and an arbitrary ion beam diameter on the surface of a Ga _x I n ^ A s _y P _y layer including a single GaAs and InP substrate. The Ga ion controlled to the ion current density is injected, and the Ga _x I

The implantation G a ion in the presence or under the oxygen molecules radiating surface oxide film which is after selectively to substituted or generated G a ₂ 0 ₃ or 0 a ₂ 0 oxide layer, wherein G a _x I n _x _ _x A s

And Delahaye Tsuchingu one atomic layer of the bromide, the G a ₂ 0 ₃ or G a ₂ wherein the surface oxide film other than substituted moiety to 〇 and Ga _x I one xA S

Is to be removed. Also, before Symbol bromide, it is to use a _{_{As B r 3, PB r 3}} . Further, the _{_{_{G a x I n X _ X}}} A s y P x layer surface by controlling the injection amount of the G a ion, negative, in which can be processed in any of the positive type.

The present _{_{invention, G a x I η ι -}} X A s

Directly injecting G a ions adjusted to any ion beam diameter and the ion current density, G a _x I eta _iota one xA S yP - As to the _y layer surface is naturally formed _₂ 0 _3, As ₂ 0 , replacing the oxide such as G a ₂ 0 selectively chemically stable G a ₂ 0 _3. Their to so selectively thermally desorbed other As ₂ 0 _3, an oxide such as A s ₂ 0 under a reduced pressure environment of lower than about 10- ⁸ P a. At this time, it was replaced by a stable oxide film (G a ₂ 0 ₃₎ oxide film is used in conventional lithography Plays a mask equivalent role which had, G a _{_{_{a x I n x A s y}}} P ^ γ layer base material is etched per one atomic layer in an atmosphere of bromides such as As B r _3, spoon histological so G a ₂ 0 ₃ a stable oxide film remains on the _{_{G a x I n x a s}} y P y layer surface, Ga _x I

Can be formed. Thus, the ion beam when G a ion _{implantation, G a x I n! _} X A s by drawing a circuit pattern or the like _y P layer surface, G a ion of _{_{_{G a x I ni _ x A}}} s yy layer surface the injection unit is chemically formed From Jona G a ₂ 0 _3, remained without being etched during the dry etching ing this G a ₂ 0 ₃ is due _{_{bromide, Ga x I r ^ - X}} A s yPi — It becomes possible to process an arbitrary circuit pattern on the y-layer. Also, depending on the amount of Ga ions implanted during Ga ion implantation, the surface of the Ga _x Ir _x AsyP _y layer can be processed into either a positive type or a negative type. As described above, the ion beam microfabrication method of the present invention does not require the production and use of the dry etching mask used in the dry etching, and the control of the amount of Ga ions implanted enables the G a it is possible to freely adjust the _{_{_{_{x I ni _ x a s y}}}} P x _ y layer pattern formed on the surface. For this reason, it is possible to deal with complicated and miniaturized circuit patterns, such as circuit patterns used in recent quantum devices. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a view for explaining a difference in a forming process due to a difference in ion dose (quantity of ion implantation) in an embodiment of an ion beam fine processing method according to the present invention. FIG. 2 is a diagram showing AFM images of substrate surfaces having different ion doses (ion implantation amounts) in the ion beam fine processing method according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an example of an embodiment of an ion beam fine processing method according to the present invention will be described with reference to the drawings. In Figure 1, 1 is a G a A s layer, 2 denotes a front surface oxide film of A s ₂ 0 ₃ or the like the surface of which is naturally formed on the G a A s layer 1 surface. Further, in FIG. 1, it is shown that the implantation amount of Ga ions increases from the left to the right of the page, that is, as it moves from FIG. 1 (a) to (d).

Ion beam micromachining process according to the present embodiment, first, without removing the surface oxide film 2 such as A s ₂ 0 ₃ which is naturally formed on the G a A s layer 1 surface, the surface oxide film Irradiate the Ga ion 4 in a vacuum with the ion beam diameter of 0.5 μm or less, preferably 0.3 / m or less, more preferably 0. Inject Ga ions into 2. By injection of G a ion, and A s ₂ 0 ₃ of the surface oxide film 2, oxides such as A s ₂ 0 is the Sani匕物G a ₂ 0 ₃ 3 in injection volume or less was chemically stable in It is replaced (see Figure 1 (a) upper row). Then, the surface oxide film 2 other than G a ₂ 0 ₃ 3 By heating the G aA s layer 1 a part of the surface oxide film 2 was replaced by G a ₂ 0 ₃ 3 to 5 8 0 ° C heat desorbed, then the surface is dry-etched by atomic layer more units by morphism irradiation with bromides, removing the non-replacement portion of the Ga ₂ 0 _{3 3} (FIG. 1 (a) see bottom). At this time, if the surface of the GaAs layer 1 is patterned with a Ga ion so as to have a predetermined circuit pattern, an arbitrary circuit pattern can be processed on the surface of the GaAs layer 1.

Here, according to this dry etching, it is possible to obtain a surface with good flatness with good reproducibility. Specifically, in this bromide etching, the atoms to be etched are the atoms at the step positions and the kink positions on the surface, and the step kinks that constitute the surface irregularities. In order to remove Pb preferentially, the atomic layer can be etched one layer at a time. The surface obtained as a result of such single layer etching is extremely flat. That is, a flat surface at the atomic level can be obtained. Furthermore, this method enables the same etching regardless of the index of the surface, even on the cleaved (110) plane. For this reason, the surface of the GaAs crystal is etched in a single layer regardless of the surface index on any of the (100), (110), and (111) surfaces, that is, the etching depth in nano-order units. , And the side shape of the processing area can be controlled on the spot.

In this dry etching, a bromide gas is used in an ultra-high vacuum, for example, with a pressure of 10 to ⁸ Pa, and then 500 to 600 at 10 to ¹⁶ : L 0 to ⁵ Pa V Etching can be performed by introducing an etchant gas under a partial pressure of a group III molecular gas. Examples of the bromide used as a Etsu etchant gas is preferably exemplified as PB r ₃ which is a compound of the A s B r _3, also P is a compound with A s is the typical . Of course, it may be of another kind.

As described above, since it is possible to etch the surface atomic layer one layer at a time, Ga _x I! ! G xA S

It is possible to surface oxide film present on the layer surface is processed in a chemically stable G a ₂ 0 ₃ nano portions other than substituted in 'order unit of fine size formed by irradiation of the Ga ions In addition, a fine structure having a high aspect ratio can be easily formed with good reproducibility, and negative lithography can be performed.

By irradiating the Ga ions 4 at a higher ion current density than in the case described above and increasing the injection amount, as shown in FIG. 1 (b), when the predetermined injection amount is exceeded, G a ₂₀ _The 33 film is sputtered, and the Ga ions enter the GaAs layer 1 and the Ga ions are implanted into the GaAs layer 1. And G By the implantation of the a ions, the GaAs layer 1 becomes an amorphized GaAs layer 5, and a groove is formed on the surface (see the upper part of FIG. 1 (b)). Then, a part of the surface oxide film 2 are dry-etched with G a ₂ O ₃ 3 to substituted G a A s layer atomic layer more units by bromide surface 1, is replaced by a G a ₂ 0 ₃ 3 and other portions, and removal of the sputtered-ring portion depends on G a ion及Pi G a ₂ 〇 ₃ 3, it is patterned surface in a predetermined pattern in which the grooves are formed in the apex portion (Fig. 1 (B) See below).

As shown in FIG. 1 (c), when the amount of Ga ions 4 implanted into the surface oxide film 2 is increased, As ₂ 0 ₃ and 3 ₂ 0 formed on the surface become 0 a ₂ 0 ₃ 3 gradually replaced the force the same manner as described above, it exceeds a certain predetermined G a ion dose, G a ₂ 0 ₃ 3 is to be sputtered by G a ion (FIG. 1 (c) refer to top) . Then, 0 & ₃ layers 1 to 0 Ion By is injected, 0 & 3 layer 1 becomes 0 and 3-layer 5 was amorphous. The amorphous GaAs layer 5 exhibits a higher etching rate than the single crystal GaAs. For this reason, the surface of the 0 & 3 layer 1 is evacuated to a level of 10 ^-8 Pa in an ultra-high vacuum using a bromide gas, and then, at 500 to 600 ° C, 10 to ⁶ to 10 — When dry etching is performed by introducing an etchant gas at a gas partial pressure of ⁵ Pa, the etching is performed faster than the portion where Ga ions 4 are not implanted, as shown in the lower part of Fig. 1 (c). In addition, the etched amount is larger than the outside of the groove, and a deeply etched V-groove is formed inside.

Furthermore, when the amount of implanted Ga ions is increased, the range of amorphousization of the GaAs layer 1 is expanded, and sputtering is performed by the Ga ions (see the upper part of Fig. 1 (d)). The surface of the G aA s layer 1, after evacuation of the in ultrahigh vacuum using the aforementioned Similarly odor-fluorinated gases, for example to 1 0 _ ⁸ P a level, at 500~600 ° C 10- ⁶ ~1 ^0-5 Etchiyan in gas partial pressure P a When dry etching is performed by introducing gas, deep grooves can be machined on the surface (see the lower part of Fig. 1 (d)).

Thus, according to the ion beam microfabrication method according to the present invention, without having to remove the surface oxide film such as A s ₂ 0 ₃ which is naturally formed on the Ga A s layer surface, said surface oxide film by implanting G a ion, it is possible to form a chemically stable G a ₂ 0 ₃ on the surface. By controlling the amount of Ga ion to be injected, the surface of the GaAs layer after dry etching with bromide can be processed into either a negative type or a positive type. Further, by drawing the surface of the GaAs layer with an ion beam so as to form a predetermined circuit pattern at the time of the Ga ion implantation, an arbitrary circuit pattern can be easily processed with good reproducibility. This makes it possible to apply not only to semiconductor devices, but also to wavelength discrimination devices, micromachining of micromachining 'and microcomponents, and quantum wires and quantum boxes.

In the present embodiment has described the G a A s layer, if _{_{G a x I n! _ X}} A s y P i_ y layer is, G a A s layer described in this embodiment and The same effect is achieved, and the present invention is not limited to the GaAs layer.

Hereinafter, the present invention will be described more specifically with reference to examples.

(Example 1)

G a A s layer A s which is naturally formed on the surface ₂ 0 ₃ or the like toward the surface of the surface oxide film of the G a ions focused ion beam diameter 0. 1 μπι in vacuo 6 X 10 ¹³ Irradiation is performed at an acceleration voltage of 30 kV / cm ² and Ga ions are implanted into the surface oxide film. After G a ion implantation, and placed in an ultra-high vacuum device, after evacuation to 1 0 ~ ⁸ P a level, the temperature was raised to 580 ° C, after removal of the oxide film other than G a ₂ 0 _3, 500-630 ° introducing a s B r 3 gas at the gas partial pressure of C at 10- ⁶ ~10- ⁵ P a performing Etsuchingu by. Figure 2 (a) shows an atomic force microscope (AFM) image of the surface. As shown in FIG. 2 (a), the Ga As layer surface, part G a ion that has not been etched by As B r ₃ gas is injected surface oxidation film is replaced by a G a ₂ 0 ₃ It can be observed that is formed in a convex shape.

(Example 2)

After the Ga ions were implanted in the same manner as in Example 1 except that the amount of implanted Ga ions was 6 × 10 ¹⁴ / cm ² , the surface was dry-etched with AsBr ₃ gas.

Second diagram (b), injecting the region center portion dose (injection amount) is locally increased stable G a ₂ 0 ₃ is sputtering, a groove on the apex portion is formed pattern is formed Can be observed.

(Example 3)

After the Ga ions were implanted in the same manner as in Example 1 except that the implanted amount of Ga ions was 6 × 10 ¹⁵ / cm ² , the surface was dry-etched with AsBr ₃ gas.

Figure 2 (c) shows an AFM image of the surface. Uni shown in FIG. 2 (c), the GaAs layer surface, by G a ion, that the GaAs layer is Amonore Fas reduction, tends deep trench etched into the A s B r ₃ is made form Can be observed.

(Example 4)

After the Ga ions were implanted in the same manner as in Example 1 except that the amount of implanted Ga ions was set to 6 × 10 ¹⁷ Zcm ² , the surface was dry-etched with AsBr ₃ gas.

Figure 2 (d) shows an AFM image of the surface. As shown in Fig. 2 (d), the GaAs layer is amorphous on the surface of the GaAs layer by Ga ions. By reduction, the easier becomes deep trench etched into As B r ₃ are formed can be observed.

As described above, G a A a surface oxide film s layer formed on the surface by injecting G a I O emissions, such etched by bromide les,-chemical stable G a ₂ 0 ₃ By controlling the amount of injected Ga ions, the pattern formed on the GaAs layer surface can be processed into either a positive type or a negative type. Industrial applicability

As described above in detail, the present _{_{_{invention, Ga x I ni - x As}}} yPi- y layer without removing the front surface oxide film which is naturally formed on the semiconductor crystal surface comprising a compound semiconductor such as, the surface oxidation by injecting G a Ion membrane, it is possible to form a chemically stable G a ₂ 0 ₃ that is not etched by bromide. Therefore, an arbitrary circuit pattern can be processed on the surface without using a mask for etching at the time of etching as in the related art. Furthermore, by the child controls the injection amount of G a _{_{_{ion, G a x I ni _ x}}} A s y Pi- y layer pattern of a positive type formed on the surface, can be processed in any of the negative Becomes This will enable the realization of useful elements, such as quantum wires, quantum boxes, diffraction gratings, and micromachines, utilizing various quantum device characteristics. Further, since it is possible to E Tsuchingu every one atomic layer, the crystal orientation of _{_{_{G a x I ni _ x A}}} s y layer, the shape of the groove to be formed can freely controllable.

Claims

The scope of the claims

1. containing a simple substance of G a A s and I n P _{substrate, G a x I n ^ A} s y P Bok _{y (0≤x, y≤} 1) on layer surface, any ion beam diameter, the ion current density implanting G a ions control whenever, the _{_{Ga x I n ^ a s y}} G a ion implantation by oxidation in the presence or oxygen molecules irradiation of the surface oxide film P is formed on the _y layer table surface after selectively to substituted or generated G a ₂ 〇 ₃ or G a ₂ 〇 layer, the _{_{_{G a x I η α _ χ}}} Α s dry more monoatomic layer units _y P ₇ layer surface bromide etched to permit a negative lithography for removing the G a ₂ O ₃ or G a ₂ O wherein the surface oxide film other than substituted moiety to and _{_{G a x I n! _ X}} a s y P DOO _y substrate Ion beam fine processing method.

2. containing a simple substance of G a A s及Pi I n P _{substrate, G a x I n ^ A} s y P y (0≤x N y≤ 1) on layer surface, any ion beam diameter, the ion current density Controlled ion implantation, and the presence of a surface oxide film formed on the surface of the Ga _{x In} _x A s _y P _y layer or implantation of Ga ions under irradiation of oxygen molecules. the acid I arsenide layer selectively is substituted or generated G a ₂ 0 ₃ or G a ₂ 0, by sputtering a portion of said G a ₂ 0 ₃ or G a ₂ 0 by the G a ion, wherein G a ₂ 0 ₃ or G a ₂ 0 sputtered portion wherein the G a ions from _{_{_{G a x I n X _ X}}} a s said injected into _y layer Ga _x I xA S

After the _y layer is amorphous, and dry etching in one atomic layer unit by bromide, G a of the G a ₂ 0 ₃ or 0 a ₂ 0 the surface oxide film and portions thereof other than the substituted part in _x l _ni xA S _yPi - _y layer and G a ion implantation has been amorphized Ga _x I n Bok _x a s _y P Bok _y layer ion beam microfabrication method that allows a positive lithography for removing.

3. The bromine compound, As B r _3, ion beam micromachining process according to claim 1 using a PB r _3.

4. The G a _x I _{eta iota} by controlling the injection amount of the G a ion - _X A s yPi _y layer surface nano 'order units etching depth situ side shape of及Pi machining area The ion beam micromachining method according to claim 1, wherein the ion beam micromachining method can be controlled by:

5. By controlling the dose of the G a ion, the G a _x I n _x

4. The ion beam micromachining method according to claim 3, wherein the etching depth of the surface of the SyPi-y layer and the side surface shape of the machining region can be controlled on the spot in nanometer order.

6. The bromine compound, As B r _3, ion beam micromachining process according to claim 2 using the PB r _3.

7. The by controlling the injection amount of the G a ion G a _x I n! _ _X A s

3. The ion beam fine processing method according to claim 2, wherein the etching depth and the side surface shape of the processing area can be controlled in situ in nano-order units.

8. The G a _x I n _x by controlling the dose of the G a ion

S The _y layer surface, a nano 'order units etch depth, range capable of controlling the side shape of及Pi machining region in situ according according to paragraph 6 ion beam microfabrication methods.