# US 4,397,724 A · Apparatus and method for plasma-assisted etching of wafers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,397,724 A - Document ID: US4397724A - Status: Granted - Kind: A - Application number: 06/295,839 - Filed: 1981-08-24 - Granted: 1983-08-09 - Earliest claimed: 1981-08-24 - Assignees: Bell Telephone Laboratories, Incorporated - Inventors: Joseph M. Moran - Web page: https://patentgrep.com/patent/US4397724A ## CPC - H10P 70/273: {the processing being a delineation of conductive layers, e.g. by RIE} - C23F 4/00: Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00 - H01J 37/32559: {Protection means, e.g. coatings} - H01J 37/34: operating with cathodic sputtering (H01J37/36 takes precedence {; methods of cathodic sputtering C23C14/34}) - H10P 50/268: {of silicon-containing layers} - H01J 2237/20: Positioning, supporting, modifying or maintaining the physical state of objects being observed or treated - Y10S 156/914: Differential etching apparatus including particular materials of construction - Y10S 156/917: Differential etching apparatus having a barrel reactor - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); 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 - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract In a plasma-assisted etching apparatus and method, surfaces in the reaction chamber are covered with a layer of a polyarylate polymer. Contamination of wafers during the etching process is thereby substantially reduced. In practice, this leads to a significant increase in the yield of acceptable chips per wafer. ## Claims ### Claim 1 Apparatus for plasma-assisted dry etching of a layer formed on a wafer, said apparatus comprising a reaction chamber, means for establishing an etching plasma within said chamber, said chamber including surfaces exposed to said plasma, and a covering of a polyarylate polymer on at least some of said surfaces. ### Claim 2 (depends on 1) An apparatus as in claim 1 wherein said polymer is selected from the group consisting of Ardel 100, Ardel 203, and Ardel 205, Ardel 208, U-Polymer. ### Claim 3 (depends on 2) An apparatus as in claim 2 further including a cathode electrode in said reaction chamber, and means including polyarylate polymer-covered surfaces mounting said wafer on said cathode electrode. ### Claim 4 (depends on 3) An apparatus as in claim 3 wherein said wafer includes a layer of aluminum to be etched, and wherein said establishing means includes means for introducing a mixture of boron trichloride and chlorine gases into said reaction chamber. ### Claim 5 (depends on 3) An apparatus as in claim 3 wherein said wafer includes a layer of polysilicon to be etched, and wherein said establishing means includes means for introducing a mixture of boron trichloride and chlorine gases into said reaction chamber. ### Claim 6 (depends on 3) An apparatus as in claim 3 wherein said wafer includes a layer of polysilicon to be etched, and wherein said establishing means includes means for introducing essentially pure chlorine gas into said reaction chamber. ### Claim 7 (depends on 3) An apparatus as in claim 3 wherein said wafer includes a layer of silicon dioxide to be etched, and wherein said establishing means includes means for introducing a mixture of trifluoromethane and ammonia gases into said reaction chamber. ### Claim 8 (depends on 3) An apparatus as in claim 3 wherein said wafer includes a layer of hardened resist material to be etched, and wherein said establishing means includes means for introducing a halocarbon and/or oxygen into said reaction chamber. ### Claim 9 (depends on 3) An apparatus as in claim 3 wherein said wafer includes a layer of tantalum disilicide to be etched, and wherein said establishing means includes means for introducing into said reaction chamber a gas from whch are derived active etchant radicals that include fluorine and chlorine constituents as the predominant etchant species for tantalum and silicon, respectively. ### Claim 10 (depends on 4) An apparatus as in claim 4 wherein said establishing means includes means for establishing the following conditions in said reaction chamber: a pressure of approximately 20 micrometers, a power density of approximately 0.15 watts per square centimeter at the surface of the layer to be etched, a gas flow into said chamber of approximately 75 volume percent boron trichloride and 25 volume percent chlorine, a gas flow into said chamber of approximately 75 cubic centimeters per minute and a dc bias voltage of said cathode electrode with respect to a point of reference potential of approximately 210 volts. ### Claim 11 (depends on 6) An apparatus as in claim 6 wherein said establishing means includes means for establishing the following conditions in said reaction chamber: a pressure of approximately 10 micrometers, a power density of approximately 0.1 watts per square centimeters at the surface of the layer to be etched, a gas flow into said chamber of approximately 40 cubic centimeters per minute and a dc bias voltage of said cathode electrode with respect to a point of reference potential of approximately 300 volts. ### Claim 12 (depends on 7) An apparatus as in claim 7 wherein said establishing means includes means for establishing the following conditions in said reaction chamber: a pressure of approximately 50 micrometers, a power density of approximately 0.16 watts per square, centimeter at the surface of the layer to be etched, a gas flow into said chamber of approximately 96 volume percent trifluoromethane and 4 volume percent ammonia, a gas flow into said chamber of approximately 30 cubic centimeters per minute and a dc bias voltage of said cathode electrode with respect to a point of reference potential of approximately 600 volts. ### Claim 13 Apparatus for plasma-assisted dry etching of a layer on a wafer that is to be processed to form multiple integrated circuits, said apparatus comprising a reaction chamber, means for establishing an etching plasma within said chamber, means within said chamber for holding a number of wafers to be etched, said chamber having internal surfaces including surfaces of said holding means in the immediate vicinity of said wafers to be etched, and a layer of a high-temperature-tolerant polyarylate polymer formed on internal surfaces including at least the surfaces of said holding means in the immediate vicinity of said wafers. ### Claim 14 (depends on 13) Apparatus as in claim 13 wherein said plasma is derived from a mixture of boron trichloride and chlorine. ### Claim 15 (depends on 13) Apparatus as in claim 13 wherein said plasma is derived from essentially pure chlorine. ### Claim 16 (depends on 13) Apparatus as in claim 13 wherein said plasma is derived from a mixture of trifluoromethane and ammonia. ### Claim 17 (depends on 13) Apparatus as in claim 13 wherein said plasma is derived from oxygen or a halocarbon and oxygen. ### Claim 18 (depends on 13) Apparatus as in claim 13 wherein said establishing means includes means for introducing into said reaction chamber a gas from which are derived active etchant radicals that include fluorine and chlorine as the predominant etchant species. ### Claim 19 A method for fabricating VLSI devices by delineating fine-line patterns on a wafer in accordance with a process sequence that includes plasma-assisted dry etching, said method comprising the steps of mounting said wafer to be etched in a reaction chamber at least some of whose surfaces are covered with a layer of a polyarylate polymer, and establishing an etching plasma within said chamber. ### Claim 20 (depends on 19) A method as in claim 19 wherein said polymer is selected from the group consisting of Ardel 100, Ardel 203, Ardel 205, Ardel 208 and U-Polymer. ### Claim 21 (depends on 20) A method as in claim 20 wherein a cathode electrode is included in said reaction chamber and said wafer to be etched is mounted on said cathode electrode. ### Claim 22 (depends on 21) A method as in claim 21 wherein said wafer includes a layer of aluminum to be etched, and wherein said establishing step includes introducing a mixture of boron trichloride and chlorine gases into said chamber. ### Claim 23 (depends on 21) A method as in claim 21 wherein said wafer includes a layer of polysilicon to be etched, and wherein said establishing step includes introducing a mixture of boron trichloride and chlorine gases into said chamber. ### Claim 24 (depends on 21) A method as in claim 21 wherein said wafer includes a layer of polysilicon to be etched, and wherein said establishing step includes introducing essentially pure chlorine gas into said chamber. ### Claim 25 (depends on 21) A method as in claim 21 wherein said wafer includes a layer of silicon dioxide to be etched, and wherein said establishing step includes introducing a mixture of trifluoromethane and ammonia gases into said chamber. ### Claim 26 (depends on 21) A method as in claim 21 wherein said wafer includes a layer of hardened resist material to be etched, and wherein said establishing step includes introducing a halocarbon and/or oxygen into said chamber. ### Claim 27 (depends on 21) A method as in claim 21 wherein said wafer includes a layer of tantalum disilicide to be etched, and wherein said establishing step includes introducing into said chamber a gas from which are derived active etchant radicals that include fluorine and chlorine constituents as the predominant etchant species for tantalum and silicon, respectively. ### Claim 28 (depends on 22) A method as in claim 22 wherein said establishing step includes establishing the following conditions within said chamber: a pressure of approximately 20 micrometers, a power density of approximately 0.15 watts per square centimeter at the surface of the layer to be etched, a gas flow into said chamber of approximately 75 volume percent boron trichloride and 25 volume percent chlorine, a gas flow into said chamber of approximately 75 cubic centimeters per minute and a dc bias voltage of said cathode electrode with respect to a point of reference potential of approximately 210 volts. ### Claim 29 (depends on 24) A method as in claim 24 wherein said establishing step includes establishing the following conditions within said chamber: a pressure of approximately 10 micrometers, a power density of approximately 0.1 watts per square centimeter at the surface of the layer to be etched, a gas flow into said chamber of approximately 40 cubic centimeters per minute and a dc bias voltage of said cathode electrode with respect to a point of reference potential of approximately 300 volts. ### Claim 30 (depends on 25) A method as in claim 25 wherein said establishing step includes establishing the following conditions within said chamber: a pressure of approximately 50 micrometers, a power density of approximately 0.16 watts per square centimeter at the surface of the layer to be etched, a gas flow into said chamber of approximately 96 volume percent trifluoromethane and 4 volume percent ammonia, a gas flow into said chamber of approximately 30 cubic centimeters per minute and a dc bias voltage of said cathode electrode with respect to a point of reference potential of approximately 600 volts. ### Claim 31 Apparatus for plasma-assisted dry etching of a layer formed on a wafer, said apparatus comprising a reaction chamber, means for establishing an etching plasma within said chamber, said chamber including surfaces exposed to said plasma, and a covering of Ekonol Polymer on at least some of said surfaces. ### Claim 32 A method for fabricating VLSI devices by delineating fine-line features on a wafer in accordance with a process sequence that includes plasma-assisted dry etching, said method comprising the steps of mounting said wafer to be etched in a reaction chamber at least some of whose surfaces are covered with a layer of Ekonol Polymer, and establishing an etching plasma within said chamber.