Abstract A process for forming a semiconductor device isolation region which comprises: a) forming on a silicon substrate at least a first thin silicon oxide film and a first silicon nitride film thereon, b) etching the substrate using a resist pattern to form a trench for providing an isolation region, c) forming a second silicon oxide film and a second silicon nitride film on the side walls and bottom wall of the trench, d) subsequently forming a first polycrystalline silicon film on the substrate including the trench, leaving the first polycrystalline silicon film only on the side walls of the trench by anisotropic etching and thereafter oxidizing the remaining first polycrystalline silicon film to form an oxide film on the side walls of the trench, and e) further forming a second polycrystalline silicon film over the semiconductor substrate including the trench, leaving the second polycrystalline silicon film only between the oxide film portions on the side walls of the trench by anisotropic etching and thereafter oxidizing the remaining second polycrystalline silicon film to thereby form an oxide film.
A process for forming a semiconductor device isolation region which comprises: a) forming on a silicon substrate at least a first thin silicon oxide film and a first silicon nitride film thereon, b) etching the substrate using a resist pattern to form a trench for providing an isolation region, c) forming a second silicon oxide film and a second silicon nitride film on the side walls and bottom wall of the trench, d) subsequently forming a first polycrystalline silicon film on the substrate including the trench, leaving the first polycrystalline silicon film only on the side walls of the trench by anisotropic etching, and thereafter oxidizing the remaining first polycrystalline silicon film to form an oxide film on the side walls of the trench, and e) further forming a second polycrystalline silicon film over the semiconductor substrate including the trench, leaving the second polycrystalline silicon film only between the oxide film portions on the side walls of the trench by anisotropic etching, and thereafter oxidizing the remaining second polycrystalline silicon film to thereby form an oxide film.
Claim 2
Dependent Claim
42 words
A process of claim 1 in which in the step (a), the first thin silicon oxide film is formed by oxidizing the silicon substrate and a silicon oxide film is further formed on the first silicon nitride film by a CVD method.
Claim 3
Dependent Claim
31 words
A process of claim 2 in which in the step (a), a polycrystalline silicon film is further formed between the first thin silicon oxide film and the first silicon nitride film.
Claim 4
Dependent Claim
23 words
A process of claim 1 in which the second silicon nitride film of the step (c) is formed by a LP CVD method.
Claim 5
Dependent Claim
25 words
A process of claim 1 in which the thickness of the first polycrystalline silicon film is about one-fourth of a minimum width of the trench.
Claim 6
Dependent Claim
39 words
A process of claim 1 in which the thickness of the second polycrystalline silicon film of the step (d) is one-half or more of a maximum width between the oxide film portions on the side walls of the trench.
Claim 7
Dependent Claim
74 words
A process for forming a trench isolation region in a semiconductor device by forming an isolation trench in a semiconductor substrate and filling said isolation trench with insulation material, the filling being effected by a procedure which includes oxidising a polycrystalline silicon film (8) formed on inside walls of the trench, and thereafter oxidising further polycrystalline silicon (11) introduced into the trench between the oxidised polycrystalline silicon film portions (9) on said trench walls.
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