Etching method for flattening a silicon substrate utilizing an anisotropic alkali etchant
AssigneeHitachi, Ltd.
InventorMasayoshi Yoshimura
Life of this patent
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Abstract
An epitaxial silicon layer is grown on a principal surface of the (100) crystal face of a silicon single crystal having a depressed portion in the principal surface. The epitaxial silicon layer is flattened by etching, the epitaxial silicon layer being formed to a sufficient thickness so that the side surfaces of the crystal face (111) of a new depressed portion as viewed in a vertical section (the new depressed portion being formed in a surface of the epitaxial silicon layer in correspondence with the first-mentioned depressed portion) intersect at a level which is, at the lowest, the final plane of the etching. The etching is anisotropic etching with an alkali etchant, by which the epitaxial silicon layer is etched down to the final plane.
Claims10
An etching method for flattening a silicon substrate wherein an epitaxial silicon layer is grown on the (100) crystal face of the silicon single-crystal substrate, the silicon single-crystal substrate having a depressed portion in its principal face, and etching for flattening the epitaxial silicon layer is carried out;
- said method comprising the steps of forming said epitaxial silicon layer to such a sufficient thickness that a position at which side surfaces of a new depressed portion to be formed in a surface of said epitaxial silicon layer, said side surface having a crystal face (111), intersect becomes at least a final surface of the etching, and subjecting said epitaxial silicon layer to anisotripic etching with an alkali etchant down to said final surface.
A method of manufacturing a semiconductor device wherein an epitaxial silicon layer is grown on a principal face of a silicon single-crystal substrate which is the (100) crystal face, the silicon single-crystal substrate having depressed portions in its principal face, and etching for flattening the epitaxial silicon layer is carried out;
- comprising the steps of forming said epitaxial silicon layer to such a sufficient thickness that a position at which side surfaces of each of new depressed portions to be formed in a surface of said epitaxial silicon layer, said side surface having a crystal face (111), intersect becomes at least a final surface of the etching, subjecting said epitaxial silicon layer to anisotropic etching with an alkali etchant, and subsequently doping selected parts of said epitaxial silicon layer outside a surface of said depressed portion of said substrate with an impurity of the same conductivity type as that of said substrate to the extent that the impurity-doped layers extend to said substrate.
A method of manufacturing a semiconductor device comprising the steps of:
- a. removing a prescribed portion of semiconductor material from the (100) crystal face of a silicon single crystal substrate so as to form a depression in said substrate;
- b. epitaxially growing a silicon layer on said (100) crystal face and in the depression of said substrate so as to fill said depression and so that said layer extends above the original (100) crystal face of said substrate while leaving a depression in said silicon layer above the depression in said substrate;
- and
- c. subjecting said epitaxially grown silicon layer to anisotropic etching with an alkali etchant;
- and wherein
- step (b) comprises epitaxially growing said silicon layer to a thickness such that lines extending along the side surfaces of the depression in said silicon layer, as said silicon layer is etched by said alkali etchant, intersect at a point no deeper from the surface of said silicon layer than the extent to which said silicon layer is etched.
Dependencies are inferred from the claim text.