WO2002007198A2 - Deposition of low stress tantalum films - Google Patents
Deposition of low stress tantalum films Download PDFInfo
- Publication number
- WO2002007198A2 WO2002007198A2 PCT/US2001/022062 US0122062W WO0207198A2 WO 2002007198 A2 WO2002007198 A2 WO 2002007198A2 US 0122062 W US0122062 W US 0122062W WO 0207198 A2 WO0207198 A2 WO 0207198A2
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- WIPO (PCT)
- Prior art keywords
- substrate
- tantalum
- temperature
- deposition
- films
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
- H01L21/76841—Barrier, adhesion or liner layers
- H01L21/76843—Barrier, adhesion or liner layers formed in openings in a dielectric
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
- H01L21/285—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation
- H01L21/28506—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers
- H01L21/28512—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic Table
- H01L21/2855—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic Table by physical means, e.g. sputtering, evaporation
Definitions
- This invention relates to the deposition of low stress tantalum films. More particularly, this invention relates to the deposition of tantalum films at low temperatures.
- barrier or liner layer is made of titanium, titanium nitride, a combination thereof, or tantalum and/or tantalum nitride, and titanium and tantalum compounds containing various amounts of oxygen. Tantalum-containing layers have been found to be better than titanium as barrier layers for copper.
- Deposition of metals onto patterned substrates has generally been done by sputtering.
- a target sputters in all directions, it is difficult to uniformly fill a high aspect ratio opening in a substrate because little of the sputtered material is deposited from a vertical direction. Thus much of the sputtered material is deposited outside of the opening, and gradually covers over the opening without filling it.
- Several methods have been tried to improve the directionality of sputtering, such as the use of a coilimator, or by biasing the substrate.
- openings having an aspect ratio higher than about 1:1 cannot be filled properly even using such methods.
- IMP chamber ionized metal plasma
- the IMP chamber 170 includes a conventional target 172, as of tantalum, mounted on a top wall 173 of the chamber 170. A pair of opposing magnets 176, 178 are mounted over the top of the target 172. A substrate support 174, bearing a substrate 175 thereon, is mounted opposite to the target 172. A source of power 180 is connected to the target 172 and a source of RF power 182 is connected to the substrate support 174. A controller 200 regulates gas flows.
- a helical coil 186 which can have one or more turns, preferably made from the same material as the target 172, is mounted between the target 172 and the substrate support 174, and is also connected to a source of RF power 188.
- Gases such as argon and nitrogen in vessels 192, 194, are metered to the chamber 170 by means of gas flow valves 196, 198 respectively.
- the pressure in the chamber is maintained by a cryogenic pump 190 through inlet 191 via a three-position gate valve 193.
- the internal inductively coupled coil 186 provides a high density plasma in the region between the target 172 and the support electrode 174. If the pressure is too low, too few particles are present and sufficient metal ionization will not occur in the region of the powered coil.
- the gate valve 193 is used to regulate the pumping speed and in turn regulate the pressure in the chamber 170 to the desired range, generally about 10-100 millitorr.
- the substrate temperature is high during deposition and the resultant tantalum films are highly compressively stressed; i.e., the films have a compressive stress as high as -2.4xlO "10 dynes/cm 2 (-2400 mPa). This is so high that the films can buckle and crack after deposition, resulting in delamination from the substrate, whereupon films such as copper, overlying the Ta layer, also delaminate.
- low stress tantalum films can be sputter deposited at low temperatures, within the range of from about 200-350°C, by carefully controlling the substrate temperature during deposition. This can be done by clamping the substrate to a temperature controllable substrate support, or providing a temperature controllable E- chuck support for the substrate during deposition of a tantalum film.
- Fig. 1 is a cross sectional view of an ionized metal plasma chamber.
- Fig. 2 is a graph of film stress in dynes/cm.2 versus the temperature of deposition.
- Fig. 3 is a cross sectional view of a temperature controllable substrate support having clamping means maintain contact between the substrate and the substrate support.
- Fig. 4 is a cross sectional view of a temperature controllable substrate support having chuck means to maintain close contact between a substrate and its support.
- Tantalum is known to exist in several forms; beta-tantalum and BCC tantalum, depending on the temperature of deposition.
- Fig. 2 which is a graph of film, stress in dynes/cm 2 versus deposition temperature, it can be seen that at film temperatures between about 200 and 350°C, beta-tantalum films are deposited and the films change to the BCC form at temperatures above that.
- beta- tantalum films must be deposited at temperatures between about 200-350°C.
- the temperature of the sputtered film must be controlled during deposition.
- a substrate support 174 can be water cooled using a pipe 197 to circulate water through the substrate support 174.
- Clamping means 195 is used to press the substrate 175 against the substrate support 174.
- a flow of an inert gas such as argon
- argon can be passed to the backside of the substrate via a line 199 during deposition, which will also aid in maintaining the desired temperature of the substrate during deposition.
- an inert gas such as argon
- the clamping ring 195 lacks contact between the substrate 175 and the substrate support 174 results in a non-uniform temperature of the substrate 175 and a consequent loss of control of the tantalum film quality.
- the substrate 175 is clamped to the support 174. This can be done using a means of clamping such as a clamp ring 195 overlying the substrate that can press the substrate 175 to the support 174.
- FIG. 4 Another means of clamping the substrate 175 to the substrate support 174 can be done by biasing the substrate support 174.
- biasing the substrate support 174 is shown in Fig. 4.
- the substrate support 174 is biased by means of an RF power supply 182A which is passed to the surface of the support.
- the surface of the substrate support 174 becomes positively charged.
- the substrate 175 is electrically attracted to the surface of the support 174, thus maintaining close spacing between the support 174 and the substrate 175,
- a line 197 circulates cooling water through the substrate support 174, ensuring efficient cooling of the support 174 during deposition.
- cooling the substrate during tantalum deposition has another advantage in that, when copper is to be deposited over the tantalum-containing film, a seed layer of copper is also deposited at low temperature. Since the seed copper layer should be deposited at as low a temperature as possible, efficient cooling of the substrate and its deposited films is required. By depositing the copper seed layer on an already cooled substrate, the time required to cool the tantalum coated substrate to the desired temperature for seed copper layer deposition is minimized, and throughput is increased. A thicker copper film can then be electroplated onto the substrate.
- Fig. 2 is a graph of the stress of a tantalum film which has been deposited in a conventional chamber that does not clamp the substrate to the support, the tensile and compressive stress in IMP sputtered tantalum films changes with temperature.
- beta-tantalum having little compressive stress can be deposited by controlling the substrate temperature while maintaining good contact between the substrate and the temperature controlled substrate support.
- the resultant tantalum film has low compressive stress and will not delaminate from the substrate. Devices made from low stress tantalum films will therefore be more reliable.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Electrodes Of Semiconductors (AREA)
- Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
Abstract
In order to deposit tantalum-containing barrier layer films for copper, the barrier layers are deposited in a high density plasma sputtering chamber. High aspect ratio openings can be filled using such a chamber, but the substrate temperature becomes elevated to temperatures that compressively stress the barrier films. Thus the films are deposited at reduced temperatures by clamping the substrate to a temperature controllable substrate support during the deposition.
Description
DEPOSITION OF LOW STRESS TANTALUM FILMS
This invention relates to the deposition of low stress tantalum films. More particularly, this invention relates to the deposition of tantalum films at low temperatures.
BACKGROUND OF THE INVENTION
With the advances made in semiconductor manufacture in the past two decades, more and more devices having smaller size features are able to be made on a single semiconductor substrate. Contact metal lines and plugs to connect various devices have traditionally been made from aluminum or an aluminum-silicon alloy. Aluminum is conductive and aluminum lines can be deposited at low temperatures, avoiding the danger of damage to already deposited device layers. However, with the arrival of devices using 0.25 micron and smaller design rules, copper, a metal that is more conductive than aluminum, is being investigated as a substitute for aluminum. Because copper is more conductive than aluminum, devices that use copper connections can operate at higher speeds.
Because metals such as aluminum and copper diffuse into underlying layers, generally silicon or silicon oxide, a barrier or liner layer has also been used. Such barrier layers are made of titanium, titanium nitride, a combination thereof, or tantalum and/or tantalum nitride, and titanium and tantalum compounds containing various amounts of oxygen. Tantalum-containing layers have been found to be better than titanium as barrier layers for copper.
The equipment used to deposit dielectric and conductive films has also become more sophisticated. Metal lines and plugs can be deposited by sputtering a conductive metal or alloys thereof. However, as the spaces to be filled with metal become smaller, the aspect ratio of these openings to be filled becomes higher.
Deposition of metals onto patterned substrates has generally been done by sputtering. However, since a target sputters in all directions, it is difficult to uniformly fill a high aspect ratio opening in a substrate because little of the sputtered material is deposited from a vertical direction. Thus much of the sputtered material is deposited
outside of the opening, and gradually covers over the opening without filling it. Several methods have been tried to improve the directionality of sputtering, such as the use of a coilimator, or by biasing the substrate. However, openings having an aspect ratio higher than about 1:1 cannot be filled properly even using such methods.
Recently a more directional sputtering chamber has been developed, called an ionized metal plasma, or IMP chamber. This chamber is shown in Fig. 1.
The IMP chamber 170 includes a conventional target 172, as of tantalum, mounted on a top wall 173 of the chamber 170. A pair of opposing magnets 176, 178 are mounted over the top of the target 172. A substrate support 174, bearing a substrate 175 thereon, is mounted opposite to the target 172. A source of power 180 is connected to the target 172 and a source of RF power 182 is connected to the substrate support 174. A controller 200 regulates gas flows. A helical coil 186, which can have one or more turns, preferably made from the same material as the target 172, is mounted between the target 172 and the substrate support 174, and is also connected to a source of RF power 188. Gases, such as argon and nitrogen in vessels 192, 194, are metered to the chamber 170 by means of gas flow valves 196, 198 respectively. The pressure in the chamber is maintained by a cryogenic pump 190 through inlet 191 via a three-position gate valve 193.
Providing that the pressure in the chamber is fairly high, i.e., about 10 to a few hundred millitorr, the internal inductively coupled coil 186 provides a high density plasma in the region between the target 172 and the support electrode 174. If the pressure is too low, too few particles are present and sufficient metal ionization will not occur in the region of the powered coil. The gate valve 193 is used to regulate the pumping speed and in turn regulate the pressure in the chamber 170 to the desired range, generally about 10-100 millitorr.
The combination of high energy imparted to the sputtered particles as they pass through the plasma region of the chamber, and the improved directionality caused by an ionized substrate support, imparts improved directionality to sputtered metal particles into small, high aspect ratio openings. Further, the IMP chamber improves the deposition
rate of dielectric materials such as TiN and TaN.
However, when Ta is sputtered in an IMP chamber, because of the high density plasma, which is a high energy plasma, the substrate temperature is high during deposition and the resultant tantalum films are highly compressively stressed; i.e., the films have a compressive stress as high as -2.4xlO"10 dynes/cm2 (-2400 mPa). This is so high that the films can buckle and crack after deposition, resulting in delamination from the substrate, whereupon films such as copper, overlying the Ta layer, also delaminate.
Thus a method of reducing the compressive stress of tantalum films must be found in order to make reliable devices.
SUMMARY OF THE INVENTION
We have found that low stress tantalum films can be sputter deposited at low temperatures, within the range of from about 200-350°C, by carefully controlling the substrate temperature during deposition. This can be done by clamping the substrate to a temperature controllable substrate support, or providing a temperature controllable E- chuck support for the substrate during deposition of a tantalum film. BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 is a cross sectional view of an ionized metal plasma chamber.
Fig. 2 is a graph of film stress in dynes/cm.2 versus the temperature of deposition.
Fig. 3 is a cross sectional view of a temperature controllable substrate support having clamping means maintain contact between the substrate and the substrate support.
Fig. 4 is a cross sectional view of a temperature controllable substrate support having chuck means to maintain close contact between a substrate and its support. DETAILED DESCRIPTION OF THE INVENTION
Tantalum is known to exist in several forms; beta-tantalum and BCC tantalum, depending on the temperature of deposition. As shown in Fig. 2, which is a graph of film, stress in dynes/cm2 versus deposition temperature, it can be seen that at film temperatures between about 200 and 350°C, beta-tantalum films are deposited and the films change to the BCC form at temperatures above that. Thus in accordance with the invention, beta- tantalum films must be deposited at temperatures between about 200-350°C.
In order to ensure low temperature sputter deposition of beta-tantalum in an IMP chamber, the temperature of the sputtered film must be controlled during deposition. This can be done by mounting the substrate to a temperature controllable substrate support and clamping the substrate to the support. Such a water cooled substrate support and clamp are shown in Fig. 3. Referring to Fig. 3, a substrate support 174 can be water cooled using a pipe 197 to circulate water through the substrate support 174. Clamping means 195 is used to press the substrate 175 against the substrate support 174.
In addition, a flow of an inert gas, such as argon, can be passed to the backside of the substrate via a line 199 during deposition, which will also aid in maintaining the desired temperature of the substrate during deposition. However, since such a flow of gas tends to lift the substrate away from the support, good contact between the substrate and the temperature controlled support is ensured by the clamping ring 195. Lack of contact between the substrate 175 and the substrate support 174 results in a non-uniform temperature of the substrate 175 and a consequent loss of control of the tantalum film quality. Thus the substrate 175 is clamped to the support 174. This can be done using a means of clamping such as a clamp ring 195 overlying the substrate that can press the substrate 175 to the support 174.
Another means of clamping the substrate 175 to the substrate support 174 can be done by biasing the substrate support 174. Such a biasing means is shown in Fig. 4. The substrate support 174 is biased by means of an RF power supply 182A which is passed to the surface of the support. The surface of the substrate support 174 becomes positively charged. The substrate 175 is electrically attracted to the surface of the support 174, thus maintaining close spacing between the support 174 and the substrate 175, A line 197 circulates cooling water through the substrate support 174, ensuring efficient cooling of the support 174 during deposition.
In addition to depositing low stress tantalum films, cooling the substrate during tantalum deposition has another advantage in that, when copper is to be deposited over the tantalum-containing film, a seed layer of copper is also deposited at low temperature. Since the seed copper layer should be deposited at as low a temperature as possible,
efficient cooling of the substrate and its deposited films is required. By depositing the copper seed layer on an already cooled substrate, the time required to cool the tantalum coated substrate to the desired temperature for seed copper layer deposition is minimized, and throughput is increased. A thicker copper film can then be electroplated onto the substrate.
As is shown in Fig. 2, which is a graph of the stress of a tantalum film which has been deposited in a conventional chamber that does not clamp the substrate to the support, the tensile and compressive stress in IMP sputtered tantalum films changes with temperature.
In accordance with the invention, by maintaining the temperature within the desired range, beta-tantalum having little compressive stress can be deposited by controlling the substrate temperature while maintaining good contact between the substrate and the temperature controlled substrate support.
The resultant tantalum film has low compressive stress and will not delaminate from the substrate. Devices made from low stress tantalum films will therefore be more reliable.
Although the invention has been described in terms of specific sputtering chambers and specific materials, one skilled in the art can substitute other chambers and other barrier layers, which are meant to be included herein. The invention is only meant to be limited by the scope of the appended claims.
Claims
1. A method of depositing low compressive stress barrier layers on a substrate in a sputtering chamber comprising sputtering a barrier layer metal onto the substrate while it is clamped to a temperature controllable substrate support so as to deposit a barrier layer having low compressive stress.
2. A method according to claim 1 wherein the barrier layer is a tantalum-containing layer.
3. A method according to claim 1 wherein the temperature of the substrate during deposition is maintained between about 200-350°C.
4. A method of depositing low compressive stress barrier layers on a semiconductor substrate in an ionized metal plasma sputtering chamber comprising sputtering tantalum while maintaining the temperature of the substrate between about 200-350°C by clamping the substrate to a temperature controlled substrate support.
5. A method according to claim 4 wherein the substrate is clamped by means of a clamping ring.
6. A method according to claim 4 wherein the substrate is electrostatically clamped to the substrate support.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US61836400A | 2000-07-18 | 2000-07-18 | |
| US09/618,364 | 2000-07-18 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| WO2002007198A2 true WO2002007198A2 (en) | 2002-01-24 |
| WO2002007198A3 WO2002007198A3 (en) | 2002-07-18 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US2001/022062 WO2002007198A2 (en) | 2000-07-18 | 2001-07-13 | Deposition of low stress tantalum films |
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| Country | Link |
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| WO (1) | WO2002007198A2 (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997041598A1 (en) * | 1996-04-26 | 1997-11-06 | Sony Corporation | Apparatus and method for improved deposition of conformal liner films and plugs in high aspect ratio contacts |
| EP0840360A2 (en) * | 1996-11-05 | 1998-05-06 | Applied Materials, Inc. | Wafer support with improved temperature control |
| WO1998054377A2 (en) * | 1997-05-27 | 1998-12-03 | Applied Materials, Inc. | Stress tuned tantalum and tantalum nitride films |
| EP0939437A2 (en) * | 1998-02-27 | 1999-09-01 | Nec Corporation | Planarization of wiring layers |
-
2001
- 2001-07-13 WO PCT/US2001/022062 patent/WO2002007198A2/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997041598A1 (en) * | 1996-04-26 | 1997-11-06 | Sony Corporation | Apparatus and method for improved deposition of conformal liner films and plugs in high aspect ratio contacts |
| EP0840360A2 (en) * | 1996-11-05 | 1998-05-06 | Applied Materials, Inc. | Wafer support with improved temperature control |
| WO1998054377A2 (en) * | 1997-05-27 | 1998-12-03 | Applied Materials, Inc. | Stress tuned tantalum and tantalum nitride films |
| EP0939437A2 (en) * | 1998-02-27 | 1999-09-01 | Nec Corporation | Planarization of wiring layers |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2002007198A3 (en) | 2002-07-18 |
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