Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
305 words
A method of fabricating a MOS semiconductor device, comprising the steps of: (a) preparing a silicon substrate; (b) selectively forming a field oxide layer on one of opposite major surfaces of said substrate in such a manner as to surround an active region; (c) forming a first silicon oxide layer in said active region; (d) forming a polycrystalline silicon layer on said first silicon oxide layer; (e) selectively removing a part of said first silicon oxide layer and polycrystalline silicon layer such that said layers are left in a region of a gate electrode of said device and in a portion which extends from said region of said gate electrode to above said field oxide layer; (f) forming source and drain diffusion regions in said major surface of said substrate; (g) depositing a second silicon oxide layer doped with an impurity on an entire surface of a laminate which is produced by step (f), and flattening a surface of said second silicon oxide layer; (h) etching said flattened entire surface until a surface of that portion of said polycrystalline silicon layer which overlies said field oxide layer becomes bare; (i) forming a conductive layer on an entire surface of a laminate which is produced by step (h); (j) selectively removing a part of said conductive layer such that said layer is left in a region associated with said gate electrode and a portion associated with that portion of said polycrystalline silicon layer which extends to above said field oxide layer; (k) depositing a third silicon oxide layer doped with an impurity on an entire surface of laminate which is produced by step (j); and (l) forming contact holes in said third silicon oxide layer and forming a wiring which connects to said source and drain diffusion regions and said gate electrode via said contact holes.
Claim 2
Independent Claim
305 words
A method of fabricating a MOS semiconductor device, comprising the steps of: (a) preparing a silicon substrate; (b) selectively forming a field oxide layer on one of opposite major surfaces of said substrate in such a manner as to surround an active region; (c) forming a first silicon oxide layer in said active region; (d) forming a polycrystalline silicon layer on said first silicon oxide layer; (e) selectively removing a part of said first silicon oxide layer and polycrystalline silicon layer such that said layers are left in a region of a gate electrode of said device and in a portion which extends from said region of said gate electrode to above said field oxide layer; (f) forming source and drain diffusion regions in said major surface of said substrate; (g) depositing a second silicon oxide layer doped with an impurity on an entire surface of a laminate which is produced by step (f), and flattening a surface of said second silicon oxide layer; (h) etching said flattened entire surface until a surface of that portion of said polycrystalline silicon layer which overlies said field oxide layer becomes bare; (i) forming a conductive layer on an entire surface of a laminate which is produced by step (h); (j) selectively removing a part of said conductive layer such that said layer is left in a region associated with said gate electrode and a portion associated with that portion of said polycrystalline silicon layer which extends to above said field oxide layer; (k) depositing a third silicon oxide layer doped with an impurity on an entire surface of laminate which is produced by step (j); and (l) forming contact holes in said third silicon oxide layer and forming a wiring which connects to said source and drain diffusion regions and said gate electrode via said contact holes.
Claim 3
Dependent Claim
43 words
A method in accordance with claim 1, wherein step (a) compises preparing a silicon substrate having p-type conductivity while step (f) comprises forming source and drain diffusion layers each having n-type conductivity, whereby an n-channel MOS transistor is formed in said active region.
Claim 4
Dependent Claim
18 words
A method in accordance with claim 1, wherein step (d) comprises doping said polycrystalline silicon layer with phosphor.
Claim 5
Dependent Claim
30 words
A method in accordance with claim 2, wherein step (f) comprises implanting As ions in said major surface of said substrate to form said n-type source and drain diffusion regions.
Claim 6
Dependent Claim
20 words
A method in accordance with claim 2, wherein the impurity doped at step (g) comprises one of boron and arsenic.
Claim 7
Dependent Claim
23 words
A method in accordance with claim 2, wherein said conductive layer formed at step (i) is formed from one of silicide and metal.
Claim 8
Dependent Claim
43 words
A method in accordance with claim 6, wherein the silicide is selected from a group consisting of WSi 2 , MoSi 2 , TaSi 2 and TiSi 2 while the metal is selected from a group consisting of W, Mo, Ta and Ti.
Claim 9
Dependent Claim
25 words
A method in accordance with claim 2, wherein the impurity doped at step (k) is selected from a group consisting of phosphor, boron and arsenic.