GB2087315A - Plasma etching of aluminium - Google Patents

Plasma etching of aluminium Download PDF

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Publication number
GB2087315A
GB2087315A GB8130894A GB8130894A GB2087315A GB 2087315 A GB2087315 A GB 2087315A GB 8130894 A GB8130894 A GB 8130894A GB 8130894 A GB8130894 A GB 8130894A GB 2087315 A GB2087315 A GB 2087315A
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gas
order
electrodes
pressure
chamber
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GB8130894A
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GB2087315B (en
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Branson International Plasma Corp
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Branson International Plasma Corp
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture 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
    • H01L21/18Manufacture 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
    • H01L21/30Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3205Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
    • H01L21/321After treatment
    • H01L21/3213Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
    • H01L21/32133Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only
    • H01L21/32135Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only
    • H01L21/32136Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only using plasmas
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23FNON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F4/00Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Chemical & Material Sciences (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Computer Hardware Design (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Power Engineering (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • ing And Chemical Polishing (AREA)
  • Drying Of Semiconductors (AREA)

Abstract

Process and gas mixture for etching aluminium in a plasma environment in a planar reactor. The gas mixture comprises a primary etching gas mixture and a secondary gas which controls the anisotropic character of the etch. A stable uniform plasma is generated at relatively high pressure and power levels, and this provides substantially faster removal of aluminium than has heretofore been possible in planar reactors. The primary gas mixture may comprise BCl3 + Cl2, or CCl4 + Cl2. The secondary gas may be SiCl4, CHCl3 or CCl4.

Description

SPECIFICATION Process and gas mixture for etching aluminum This invention pertains generally to etching processes and gases and more particularly to a process and gas mixture for etching aluminum in a plasma environment.
In a planar plasma reactor, the material to be processes is positioned between a pair of electrode plates which are energized with radio frequency power to ionize a reagent gas and form active species for carrying out the desired process. Such reactors are utilized, for example, for etching silicon, silicon dioxide, silicon nitride, aluminum and other materials in the fabrication of semiconductor devices.
Heretofore, plasma etching processes have been carried out at relatively low pressure (e.g. 100-600 microns) in planar reactors. With higher pressures, it is difficult to strike and maintain a stable uniform plasma, and photoresist masking tends to breakdown. Aluminium is typically etched in such systems at a relatively slow rate, e.g., 1500 angstroms/ minute. Throughout this application, the term aluminum is used generally to include pure aluminum and aluminum alloys such as an aluminum-silicon alloy containing up to 2 percent silicon.
It is in general an object of the invention to provide a new and improved process and gas mixture for etching aluminum in a plasma reactor.
Another object of the invention is to provide a process and gas of the above character which are capable of anistropically removing aluminum more rapidly than conventional techniques, without photoresist breakdown.
Another object of the invention is to provide a process and gas mixture of the above character utilizing higher pressures and power densities than conventional etching processes in planar reactors.
These and other objects are achieved in accordance with the invention by employing a gas mixture comprising a primary etching gas mixture containing BCI3 and chlorine, or CCl4 and chrlorine, and a secondary gas such as CHCIB or SiC14 for controlling the anistropic character of the etch. The aluminum to be etched is placed between the electrodes of the reactor, the primary etching mixture is admitted at a pressure on the order of 20-500 microns, and the secondary gas is admitted at a pressure on the order of 20-150 microns. The electrodes are then energized to ionize the gas and form active species in the region between the electrodes.A third gas such as helium is introduced at a pressure on the order of 0.5-7 torrto prevent breakdown of photoresist in proximity to the aluminum.
The single Figure of drawing is a chematic illustration of one embodiment of apparatus for carrying out the process of the invention.
As illustrated in the drawing, the process is carried out in a planar reactor 10 having a housing 11 defining a reaction chamber 12. The housing is provided with a suitable access door (not shown) through which wafers ro other materials to be etched are introduced into and removed from the chamber. The reactor also includes a pair of planar electrodes 13,14 which are spaced apart in a generally parallel relationship within the chamber. In one presently preferred embodiment, the electrodes are circular plates having a diameter on the order of 3 1/2 - 4 1/2 inches, and they are spaced apart by a distance on the order of 0.5 - 2 inches. The electrodes are energized by a radio frequency generator 16 which is connected to the electrodes by leads 17, 18.
The generator operates at a suitable frequency (e.g.
13.56 MHz) and delivers a power output on the order of 50-500 watts to produce an electric field for ionizing the gas to form a plasma in the region between the electrodes. During operation of the reactor, the electrodes are maintained at a temperature on the order of 5-40 C by coolant circulating through passageways (not shown) in the electrodes.
Upper electrode 14 is grounded electrically to reactor housing 11, and lower electrode 13 is insulated from the housing.
A DC bias can be applied to the electrodes by a DC supply 19 which is connected electrically in parallel with RF generator 16. The bias consists of a voltage on the order of 150 volts or less, and it serves to make the etch more anisotropic, as well as reducing the amount of residue left on the material being etched and helping to preserve the integrity of photoresist.
A wafer 21 to be processed is positioned between the electrodes, and in the embodiment illustrated, this wafer is mounted on the bottom surface of upper electrode 14. The wafer is secured to the electrode by a vacuum chuck or other suitable means (not shown).
Gas is supplied to the chamber through a manifold 23 and an inlet line 24. Lower electrode 13 is fabricated of a porous material, and the gas is diffused into the chamber through this electrode.
Introducing the gas in this manner has been found to provide faster and more uniform etching of the aluminum than would otherwise be possible. An exhaust pump 26 is connected to an exhaust port 27 for removing gas from the reactor chamber and maintaining the desired level of pressure within the chamber.
The reagent gas comprises a mixture of a primary etching gas mixture and a secondary gas for controlling the anistropic character of the etch. Athird gas is included in the mixture to prevent the breakdown of photoresist. As illustrated in the drawing, the gases are supplied by an etching gas source 31, a secondary gas source 32, and a third gas source 33. The delivery of gas to the chamber from the respective sources is controlled by flow control valves 36-38.
In one presently preferred embodiment, the primary etching gas consists of a mixture of BCl3 at a pressure on the order of 100-200 microns and chlorine at a pressure on the order of 100-200 microns, the secondary gas consists of SiCI4 at a pressure on the order of 190-300 microns, and helium at a pressure on the order of 700 microns 2.5 torr is included to prevent photoresist breakdown.
The wafer to be etched is placed in the reactor chamber, and the chamber is evacuated by means of exhaust pump 26, following which the gases are admitted at the desired pressures. The DC bias, if any, and the RF power are then applied to the electrodes to ionize the gas and form a plasma of active species in the region between the electrodes.
When the desired amount of aluminum has been removed, the electrodes are deenergized, the reagent gases are purged from the chamber, and the wafer is removed.
With the relatively high pressure employed in the etching process, it is possible to use a greater power denistythan has heretofore been possible in planar reactors. This results in faster removal of aluminum than has heretofore been possible. With a 3 1/2 - 4 1/2 inch electrodes, an energizing power of 50-400 watts has been found to give good results. The aluminum is removed at a rate on the rder of 5,000-50,000 angrstoms/m inute compared to only about 1500 angstroms/minute with prior art techniques.
The significant increase in etching rate provided by the invention makes it feasible to process wafers on an individual basis, rather than in batches. For example, a one micron film of aluminum can be removed from a 3 inch wafer patterned with AZ-1350 positive photoresist in approximately one minute.
The combination of gases employed in the process is important. The primary gas mixture determines the etching rate, i.e., the rate at which the aluminum is removed, and the secondary gas controls the anistropic character or direction of the etch and prevents undercutting of photoresist. The third gas is a good thermal conductor, and it also helps in preventing degredation of the photoresist. One presently preferred gas mixture comprises a primary gas mixture consisting of BCl3 at a pressure on the order of 150 microns and chlorine at a pressure on the order of 155 microns, a secondary gas consisting of SiCI4 at a pressure on the order of 210 microns, and a third gas consisting of helium at a pre order of 1.1 torr. However, other gases can be employed in the mixture.For example, a mixture of CCl4 and chlorine can be employed at the primary etching gas, and CH3CI and/or CCl4 can be employed as the secondary gas.
The etching process and gas mixture of the invention have a number of important features and advantages. Generation of a stable, uniform plasma at higher pressure and power levels has provided significantly faster etching of aluminum than has been possible heretofore in a planar reactor. Because of this increase in speed, wafers can be processed on an individual basis rather than in batches. The use of a high pressure in combination with a high power keeps the number of high energy species at a minimum, while provided a very high level of reactive species. In addition, the anistropy or directionality of the etch can be controlled, and undercutting and degradation of photoresist are minimized.
It is apparent from the foregoing that a new and improved process and gas mixture have been provided for etching aluminum in a planar reactor.
While only certain presently preferred embodiments have been described in detail, as will be apparent to those familiar with the art, certain changes and modifications can be made without departing from the scope of the invention as defined by the following claims.

Claims (17)

1. In a process for etching aluminum in a reactor having a chamber and a pair of spaced apart generally planar electrodes, the steps of: positioning the aluminum between the electrodes in the reactor chamber, admitting a primary etching gas mixture to the chamber at a pressure on the order of 140-450 microns, admitting a secondary gas to the chamber at a pressure on the order of 190-300 microns to control the anistropic character of the etch, said primary gas mixture and the secondary gas being present in the chamber at the same time, and energizing the electrodes to ionize the gas and form active species between the electrodes.
2. The process of Claim 1 wherein the primary etching gas mixture contains BC13 at a pressure on the order of 70-200 microns and chlorine at a pressure on the order of 70-250 microns.
3. The process of Claim 1 wherein the secondary gas is SiCI4.
4. The process of Claim 1 wherein the primary etching gas mixture comprises a mixture selected from the group consisting of BCl3 and chlorine, CCl4 and chlorine, and combinations thereof.
5. The process of Claim 1 wherein the secondary gas is selected from the group consisting of SiCI4, CHCl3, CCl4 and combinations thereof.
6. The process of Claim 1 wherein a third gas is admitted to the chamber to preserve the integrity of photoresist in proximity to the aluminum.
7. The process of Claim 6 wherein the third gas is helium at a pressure on the order of 0.7-2.5 torr.
8. The process of Claim 1 wherein the gas is introduced into the chamber by diffusion through one of the electrodes into the region between the electrodes.
9. The process of Claim 1 wherein a DC bias is maintained on the electrodes during the etching process.
10. The process of Claim 1 wherein the electrodes are on the order of 3 1/2 - 4 1/2 inches in diameter, separated by a distance on the order of 0.5 - 2 inches, and energized with a power on the order of 50-400 watts.
11. In a process for removing aluminum from a substrate with photoresist masking in a reactor having a chamber and a pair of generally planar electrodes, the steps of: positioning the substrate between the electrodes in the reactor chamber, admitting a primary etching gas comprising a mixture of BCl3 at a pressure on the order of 150 microns and chlorine at a pressure on the order of 155 microns to the chamber, admitting SiCi4 to the chamber at a pressure on the order of 190-300 microns to control the anisotropic character of the aluminum removal, admitting helium to the chamber at a pressure on the order of 0.7-1.1 torr to prevent breakdown of the photoresist, and energizing the electrodes to ionize the gas between the electrodes.
12. The process of Claim 11 wherein the gas is introduced into the chamber by diffusion through one of the electrodes into the region between the electrodes.
13. A gas mixture for etching aluminum in a plasma environment, comprising: a primary etching gas comprising a mixture of BCl3 at a pressure on the order of 70-200 microns and chlorine at a pressure on the order of 70-250 microns, and a secondary gas comprising SiCI4 at a pressure on the order of 190-300 microns for controlling the anistropic character of the etch.
14. The gas mixture of Claim 14 including a third gas comprising helium at a pressure on the order of 0.7-1 torr for preserving the integrity of photoresist in a proximity to the aluminum.
15. A process for etching aluminium substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
16. Agas mixtureforetching aluminium as hereinbefore set forth.
17. Apparatus for carrying out the process as claimed in claim 15 substantially as hereinbefore described with reference to the accompanying drawing.
GB8130894A 1980-10-14 1981-10-13 Plasma etching of aluminum Expired GB2087315B (en)

Applications Claiming Priority (1)

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US19661680A 1980-10-14 1980-10-14

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GB2087315B GB2087315B (en) 1984-07-18

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DE (1) DE3140675A1 (en)
GB (1) GB2087315B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2543166A1 (en) * 1983-03-25 1984-09-28 Lfe Corp COMPOSITION AND PROCESS FOR THE SELECTIVE ATTACK, USING PLASMA REACTIVE IONS, ALUMINUM AND ALUMINUM ALLOYS
FR2588279A1 (en) * 1985-02-19 1987-04-10 Oerlikon Buehrle Inc METHOD OF ENGRAVING LAYERS OF ALUMINUM / COPPER ALLOYS
US5397433A (en) * 1993-08-20 1995-03-14 Vlsi Technology, Inc. Method and apparatus for patterning a metal layer

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH061770B2 (en) * 1984-01-30 1994-01-05 株式会社日立製作所 Dry etching method
JPS61235576A (en) * 1985-04-10 1986-10-20 Tokuda Seisakusho Ltd Dry etching device
JP2681058B2 (en) * 1986-04-03 1997-11-19 アネルバ株式会社 Dry etching method
JPH0727890B2 (en) * 1986-09-19 1995-03-29 日本電気株式会社 Dry etching method
DE3821207A1 (en) * 1988-06-23 1989-12-28 Leybold Ag ARRANGEMENT FOR COATING A SUBSTRATE WITH DIELECTRICS
DE3940820C2 (en) * 1989-12-11 1998-07-09 Leybold Ag Process for the treatment of workpieces by reactive ion etching
JP6061384B2 (en) * 2013-01-17 2017-01-18 国立大学法人静岡大学 Manufacturing method of aluminum / resin bonded body and aluminum / resin bonded body

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54158343A (en) * 1978-06-05 1979-12-14 Hitachi Ltd Dry etching method for al and al alloy
US4182646A (en) * 1978-07-27 1980-01-08 John Zajac Process of etching with plasma etch gas
US4256534A (en) * 1978-07-31 1981-03-17 Bell Telephone Laboratories, Incorporated Device fabrication by plasma etching
US4208241A (en) * 1978-07-31 1980-06-17 Bell Telephone Laboratories, Incorporated Device fabrication by plasma etching
FR2432560A1 (en) * 1978-08-02 1980-02-29 Texas Instruments Inc PROCESS FOR STRIPPING METALS, ESPECIALLY ALUMINUM, WITH SILICON TETRACHLORIDE PLASMA
US4209357A (en) * 1979-05-18 1980-06-24 Tegal Corporation Plasma reactor apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2543166A1 (en) * 1983-03-25 1984-09-28 Lfe Corp COMPOSITION AND PROCESS FOR THE SELECTIVE ATTACK, USING PLASMA REACTIVE IONS, ALUMINUM AND ALUMINUM ALLOYS
FR2588279A1 (en) * 1985-02-19 1987-04-10 Oerlikon Buehrle Inc METHOD OF ENGRAVING LAYERS OF ALUMINUM / COPPER ALLOYS
US5397433A (en) * 1993-08-20 1995-03-14 Vlsi Technology, Inc. Method and apparatus for patterning a metal layer

Also Published As

Publication number Publication date
JPS57123978A (en) 1982-08-02
DE3140675C2 (en) 1991-03-07
DE3140675A1 (en) 1982-06-16
JPH0245714B2 (en) 1990-10-11
GB2087315B (en) 1984-07-18

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19971013