Use of plasma polymerized organosilicon films in fabrication of lift-off masks

• US 4,493,855 A
• Filed: 12/23/1982
• Issued: 01/15/1985
• Est. Priority Date: 12/23/1982
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Sachdev, Krishna G., Sachdev, Harbans S.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/452,549
• Time in Patent Office: 754 Days
• Field of Search: 427/41, 427/40, 427/88, 427/96, 427/259, 427/24, 430/314, 156/643, 204/192 E
• US Class Current: 438/670
• CPC Class Codes: G03F 7/094 Multilayer resist systems, e.g. planarising layers

Abstract

Pinhole-free thin films deposited by glow discharge or plasma polymerization of organosilanes, organosilazones and organosiloxanes for use as reactive ion etch oxygen barriers in multilayer resist structures, of lift-off masks, for fabrication of semiconductor devices, such as integrated circuits. The process includes deposition of thin plasma polymerized organosilicon barrier film over a radiation insensitive polymeric base layer previously coated on a substrate, followed by thermal annealing of the plasma polymerized barrier layer, over which is then coated a radiation sensitive resist layer. After definition of the desired resist pattern by imagewise exposure and development, the image is etch transferred into the barrier layer by reactive sputter etching in a fluorine containing ambient, and subsequently transferred into the base layer, down to the substrate, in an oxygen plasma, during which time the plasma deposited film functions as an oxygen barrier. Final metal patterns are formed by metallization and lift-off steps.

Claims

1. A method for forming a patterned metal coating on an oxidized monocrystalline silicon substrate having at least one via hole in said oxide to expose surface adjacent portions of said substrate, and with said substrate having at least one integrated circuit formed therein in electrical communication with said via hole, comprising:

A. blanket depositing a first film of a solvent soluble organic polymer over the oxidized surface and said exposed portions of said substrate, with said first polymeric film being subject to reactive ion etching in an oxygen containing ambient;

B. plasma polymerizing over said first film a second oxygen barrier film of an organosilicon polymer film, with said second film being subject to etching in a fluorine containing ambient;

C. heat treating said second film for about 10 to about 30 minutes at a temperature in the range of about 85°

C. to about 300°

C. to cross-link said second film,

D. depositing over said second film a resist layer subject to etching in an oxygen containing ambient, including exposing and developing said resist to form a pattern of openings at least one of which is in register with a corresponding one of said via holes, and expose therebetween the corresponding portions of said second film;

E. reactive ion etching in a fluroine containing ambient the exposed portions of said second to replicate said pattern of openings in said second film and expose corresponding portions of said first film;

F. reactive ion etching in an oxygen containing ambient the said exposed portions of said first film to replicate said pattern of openings through said first film and remove said resist from remaining portions of said second film whereby said second film is treated by an oxygen plasma;

G. depositing a blanket coating of a conductive film on said substrate inclusive of said openings over said substrate; and

H. subjecting composite structure to said solvent to solvate said polymeric first film and concurrently lifting-off all superimposed films thereon so as to retain said metal film on the said exposed portions of said substrate.

2. The method of claim 1 wherein said organosilicon polymer film is formed by polymerization of monomers selected from the group consisting of organosilicones, organosilanes, organosiloxanes and mixtures thereof.

3. The method of claim 1 wherein said organosilicon polymer film is formed by polymerization of monomers represented by the formulas:

##STR5## where X is zero or oxygen, NH, NR₁, CH₂, ##STR6## R is CH₃, --CH═

CH₂, --O--CH₃, --O--CH₂ ═

CH₂, ##STR7## and R₁ is an alkyl group.

4. The method of claim 1 wherein said organosilicon polymer film is formed by polymerization of monomers represented by the formula:

##STR8## where Y is R, or OR;

Z is --CH═

CH₂, --CH.tbd.CH, OR, phenyl or aminoalkane group; and

R₁ are an alkyl.

5. A method for forming a patterned metal coating on an oxidized monocrystalline silicon substrate having at least one via hole in said oxide to expose surface adjacent portions of said substrate, and with said substrate having at least one integrated circuit formed therein in electrical communication with said via hole, comprising:

A. blanket depositing a first film of a solvent soluble organic polymer over the oxidized surface and said exposed portions of said substrate, with said first polymeric film being subject to reactive ion etching in an oxygen containing ambient;

B. plasma polymerizing over said first film a second oxygen barrier film of an organosilicon polymer film, with said second film being subject to etching in a fluorine containing ambient;

wherein said plasma polymerizing is in ambient which includes organoboron monomers whereby said formed organosilicone polymer comprises an organoborosilicon polymer barrier film, and said oxygen plasma treatment forms a borosilicate surface layer on said barrier film

C. heat treating said second film for about 10 to about 30 minutes at a temperature in the range of about 85°

C. to about 300°

C. to cross-link said second film;

D. depositing over said second film a resist layer subject to etching in an oxygen containing ambient, including exposing and developing said resist to form a pattern of openings at least one of which is in register with a corresponding one of said via holes, and expose therebetween the corresponding portions of said second film;

E. reactive ion etching in a fluorine containing ambient the exposed portions of said second to replicate said pattern of openings in said second film and expose corresponding portions of said first film;

F. reactive ion etching in an oxygen containing ambient the said exposed portions of said first film to replicate said pattern of openings through said first film and remove said resist from remaining portions of said second film whereby said second film is treated by an oxygen plasma;

G. depositing a blanket coating of a conductive film on said substrate inclusive of said openings over said substrate; and

H. subjecting the composite structure to said solvent to solvate said polymeric first film and concurrently lifting-off all superimposed films thereon so as to retain said metal film on said exposed portions of said substrate.

6. The method of claim 5 wherein said organoboron monomer comprises trimethoxy boroxine.