Thermal trench isolation
AssigneeMicron Technology, Inc.
InventorsThomas A. Figura, Nanseng Jeng
Life of this patent
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Abstract
A process useful for isolating active areas of semiconductor devices in which an isolation trench is created in a substrate, the isolation trench being lined with an oxidation barrier and filled with a thick film. An oxidation step is performed in which the thick film is oxidized. The oxidation is self-limiting as the oxidation barrier prevents the substrate surrounding the trench from being oxidized.
Claims24
A method for forming an isolation device comprising the following steps:
- providing a semiconductor substrate having a surface;
- patterning said substrate to expose wide areas and narrow regions of said substrate surface, said narrow regions having a width less than 0.5 .mu.m;
- removing said exposed substrate to a level below said surface of said substrate;
- oxidizing said exposed substrate, thereby forming a thin oxide layer on said exposed wide areas and narrow regions of said substrate;
- forming a conformal film;
- removing essentially all of said conformal film from said wide areas and leaving a portion of said conformal film in said narrow regions;
- and
- oxidizing said wide areas of said substrate and said portion of said conformal film.
A process for isolating active areas of a semiconductor device, comprising the following steps:
- creating wide and narrow isolation trenches in a substrate, said isolation trenches being lined with an oxidation barrier and filled with a conformal film, said conformal film impinging on itself in said narrow trench, said conformal film forming a step in said wide trench;
- isotropically etching said conformal film, a portion of said conformal film remaining in said narrow trench, essentially all of said conformal film being removed from said wide trench;
- and
- oxidizing said portion of said conformal film remaining in said narrow trench.
A process for fabricating a recessed field oxide area, comprising the following steps:
- providing a substrate having isolation stacks and recesses, said recesses being wide and narrow, said recesses having openings, said recesses having a depth in the approximate range of 200 .ANG.-3000 .ANG.;
- lining said recesses with nitride;
- blanketing said substrate with a conformal material, said conformal material bridging said openings of said narrow recesses;
- removing said conformal material and said nitride from horizontal surfaces of said isolation stacks and said wide recesses;
- and
- oxidizing said substrate and said conformal material, thereby creating field oxide regions at said wide and narrow recesses.
Dependencies are inferred from the claim text.