# US 5,702,869 A · Soft ashing method for removing fluorinated photoresists layers from semiconductor substrates > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,702,869 A - Document ID: US5702869A - Status: Granted - Kind: A - Application number: 08/660,302 - Filed: 1996-06-07 - Granted: 1997-12-30 - Earliest claimed: 1996-06-07 - Assignees: Vanguard International Semiconductor Corporation - Inventors: Rong-Wu Chien; Hsiu-Lan Li - Web page: https://patentgrep.com/patent/US5702869A ## CPC - G03F 7/36: Imagewise removal not covered by groups G03F7/30 - G03F7/34, e.g. using gas streams, using plasma - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract A method for removing from a semiconductor substrate a partially fluorinated photoresist layer. There is first formed upon a semiconductor substrate a partially fluorinated photoresist layer. The partially fluorinated photoresist layer has a fluorinated surface layer of the partially fluorinated photoresist layer and an underlying non-fluorinated remainder layer of the partially fluorinated photoresist layer. The fluorinated surface layer of the partially fluorinated photoresist layer is then removed through a first etch method. The first etch method employs an oxygen containing plasma at a radio frequency power no greater than about 500 watts and a temperature no greater than about 120 degrees centigrade. Finally, the underlying non-fluorinated remainder layer of the partially fluorinated photoresist layer is removed through a second etch method. ## Claims ### Claim 1 A method for removing from a semiconductor substrate a partially fluorinated photoresist layer comprising: forming over a semiconductor substrate a partially fluorinated photoresist layer, the partially fluorinated photoresist layer having a fluorinated surface layer and an underlying non-fluorinated remainder layer; removing the fluorinated surface layer through a first etch method, the first etch method employing an oxygen containing plasma at a radio frequency power no greater than about 500 watts and a temperature no greater than about 120 degrees centigrade; and removing then the underlying non-fluorinated remainder layer through a second etch method. ### Claim 2 (depends on 1) The method of claim 1 wherein: the thickness of the partially fluorinated photoresist layer is from about 2000 to about 14000 angstroms; the thickness of the fluorinated surface layer of the partially fluorinated photoresist layer is from about 200 to about 3000 angstroms; and the thickness of the non-fluorinated remainder layer of the partially fluorinated photoresist layer is from about 1800 to about 11000 angstroms. ### Claim 3 (depends on 1) The method of claim 1 wherein the partially fluorinated photoresist layer is formed from a photoresist material chosen from the group of photoresist materials consisting of novolak photoresist materials and Poly Methyl Meth Acrylate (PMMA) photoresist materials. ### Claim 4 (depends on 1) The method of claim 1 wherein the partially fluorinated photoresist layer is fluorinated through a Reactive Ion Etch (RIE) method employing a fluorine containing Reactive Ion Etch (RIE) plasma etchant at a radio frequency power of from about 500 to about 1400 watts. ### Claim 5 (depends on 4) The method of claim 4 wherein the fluorine containing Reactive Ion Etch (RIE) plasma etchant is chosen from the group of fluorine containing plasma etchants consisting of per-fluorocarbons having no greater than three carbon atoms, hydro-fluorocarbons having no greater than three carbon atoms and nitrogen trifluoride. ### Claim 6 (depends on 1) The method of claim 1 wherein the oxygen containing plasma is an oxygen plasma. ### Claim 7 (depends on 1) The method of claim 1 wherein the oxygen containing plasma is an oxygen-nitrogen plasma containing at least about 70 percent oxygen. ### Claim 8 A method for removing from an integrated circuit layer formed upon a semiconductor substrate a partially fluorinated photoresist layer formed upon the integrated circuit layer comprising: forming over a semiconductor substrate an integrated circuit layer; forming upon the integrated circuit layer a partially fluorinated photoresist layer, the partially fluorinated photoresist layer having a fluorinated surface layer and an underlying non-fluorinated remainder layer; removing the fluorinated surface layer through a first etch method, the first etch method employing an oxygen containing plasma at a radio frequency power no greater than about 500 watts and a temperature no greater than about 120 degrees centigrade; and removing then the underlying non-fluorinated remainder layer through a second etch method. ### Claim 9 (depends on 8) The method of claim 8 wherein: the thickness of the partially fluorinated photoresist layer is from about 2000 to about 14000 angstroms; the thickness of the fluorinated surface layer of the partially fluorinated photoresist layer is from about 200 to about 3000 angstroms; and the thickness of the non-fluorinated remainder layer of the partially fluorinated photoresist layer is from about 1800 to about 11000 angstroms. ### Claim 10 (depends on 8) The method of claim 8 wherein the partially fluorinated photoresist layer is formed from a photoresist material chosen from the group of photoresist materials consisting of novolak photoresist materials, Poly Methyl Meth Acrylate (PMMA) photoresist materials. ### Claim 11 (depends on 8) The method of claim 8 wherein the partially fluorinated photoresist layer is fluorinated through a Reactive Ion Etch (RIE) method employing a fluorine containing Reactive Ion Etch (RIE) plasma etchant at a radio frequency power of from about 500 to about 1400 watts. ### Claim 12 (depends on 11) The method of claim 11 wherein the fluorine containing Reactive Ion Etch (RIE) plasma etchant is chosen from the group of plasma etchants consisting of per-fluorocarbons having no greater than three carbon atoms, hydro-fluorocarbons having no greater than three carbon atoms and nitrogen trifluoride. ### Claim 13 (depends on 8) The method of claim 8 wherein the oxygen containing plasma is an oxygen plasma. ### Claim 14 (depends on 8) The method of claim 8 wherein the oxygen containing plasma is an oxygen-nitrogen plasma containing at least about 70 percent oxygen. ### Claim 15 A method for removing from a patterned silicon oxide insulator layer within an integrated circuit a patterned partially fluorinated photoresist layer employed in patterning the patterned silicon oxide insulator layer comprising: forming over a semiconductor substrate a silicon oxide insulator layer, the semiconductor substrate having integrated circuit devices formed therein and thereupon; forming upon the silicon oxide insulator layer a patterned photoresist layer; patterning through the patterned photoresist layer as an etch mask, and by use of a Reactive Ion Etch (RIE) plasma etch method employing a fluorine containing plasma etchant, the silicon oxide insulator layer to form a patterned silicon oxide insulator layer, the Reactive Ion Etch (RIE) plasma etch method simultaneously forming from the patterned photoresist layer a partially fluorinated patterned photoresist layer comprising a patterned fluorinated surface layer and a patterned non-fluorinated underlying remainder layer; removing the patterned fluorinated surface layer through a first etch method, the first etch method employing an oxygen containing plasma at a radio frequency power no greater than about 500 watts and a temperature no greater than about 120 degrees centigrade; and removing then the patterned non-fluorinated underlying remainder layer through a second etch method. ### Claim 16 (depends on 15) The method of claim 15 wherein: the thickness of the patterned photoresist layer is from about 2000 to about 14000 angstroms; the thickness of the fluorinated surface layer of the patterned photoresist layer is from about 200 to about 3000 angstroms; and the thickness of the non-fluorinated remainder layer of the patterned photoresist layer is from about 1800 to about 11000 angstroms. ### Claim 17 (depends on 15) The method of claim 15 wherein the patterned photoresist layer is formed from a photoresist material chosen from the group of photoresist materials consisting of novolak photoresist materials and Poly Methyl Meth Acrylate (PMMA) photoresist materials. ### Claim 18 (depends on 15) The method of claim 15 wherein the patterned photoresist layer is partially fluorinated through exposure to the fluorine containing plasma etchant at a radio frequency power of from about 500 to about 1400 watts. ### Claim 19 (depends on 15) The method of claim 15 wherein the fluorine containing plasma etchant is chosen from the group of plasma etchants consisting of per-fluorocarbons having no greater than three carbon atom, hydro-fluorocarbons having no greater than three carbon atoms and nitrogen trifluoride. ### Claim 20 (depends on 15) The method of claim 15 wherein the oxygen containing plasma is an oxygen plasma. ### Claim 21 (depends on 15) The method of claim 15 wherein the oxygen containing plasma is an oxygen-nitrogen plasma containing at least about 70 percent oxygen. ### Claim 22 (depends on 15) The method of claim 15 wherein the second etch method is chosen from the group of etch methods consisting of wet chemical etch methods, dry plasma etch methods and combinations of wet chemical etch methods and dry plasma etch methods. ### Claim 23 (depends on 15) The method of claim 15 wherein the second etch method employs: an oxygen containing Reactive Ion Etch (RIE) plasma at a power of from about 500 to about 1300 watts at a radio frequency of 13.56 MHZ; and a temperature of from about 150 to about 350 degrees centigrade. ### Claim 24 (depends on 15) The method of claim 15 wherein a conductor metal contact formed beneath the silicon oxide insulator layer is reached when the silicon oxide layer is patterned to yield the patterned silicon oxide insulator layer.