Substrate structure of semiconductor device and method of manufacturing the same

Claim 2

A substrate structure of a semiconductor device comprising: a silicon substrate; an element region selectively formed on said silicon substrate and a relatively thick field oxide region formed adjacent to said element region; an element isolating region formed between said element region and said field oxide region, said element isolating region being in direct contact with said field oxide region; said element isolating region being provided with a relatively deep groove formed in said silicon substrate and having a relatively small width; a silicon oxide insulating film formed on an inner wall of said groove; and a silicon nitride insulating film disposed on said silicon oxide insulating film; wherein surfaces of said element region, the element isolating region and the field oxide region on said silicon substrate are formed substantially flat.

Claim 3

The substrate structure according to claim 1 wherein said element isolating region includes a recess defined between an inner side of said silicon nitride insulating film, said silicon nitride insulating film and said field oxide film, and a filling material filling said recess, and wherein a portion of said silicon nitride film in contact with said field oxide film is at a lower level than a portion of said silicon nitride film in contact with said element region.

Claim 4

The substrate structure according to claim 2 wherein said filling material comprises an electroconductive material capable of discharging electric charge in the adjacent insulating film.

Claim 5

The substrate structure according to claim 3 wherein said filling material is selected from the group consisting of polycrystalline silicon, semiinsulating materials and electroconductive materials.

Claim 6

The substrate structure according to claim 1 which further comprises a channel cut region formed near a bottom of said deep groove.

Claim 7

The substrate structure according to claim 1 wherein a bottom of said deep groove reaches an insulating region embedded in said silicon substrate or an insulating substrate supporting said silicon substrate.

Claim 10

The method according to claim 7 wherein said oxidation preventing layer comprises a first silicon nitride film.

Claim 11

The method according to claim 7 wherein said step (c) comprises a step of oxidizing an exposed portion of said substrate to form an etching mask layer utilized to form silicon oxide film.

Claim 12

The method according to claim 8 wherein said first film comprises a second silicon nitride film.

Claim 13

The method according to claim 8 wherein at said step (b) a third silicon nitride film is formed, and then a second film made of polycrystalline, metal or high molecular weight material is formed on said third silicon nitride film and wherein at said step (g) a second film region is formed adjacent said pattern region by etching said second film with a directive etchant, and then said first film region is formed by removing said third silicon nitride film by using said second film region as a mask.

Claim 14

The method according to claim 8 wherein at said step (b), a third silicon nitride film is formed and then a third film made of polycrystalline silicon, silicon dioxide, metal or high molecular weight material is formed on said first silicon oxide film, and wherein at said step (c) said third film is etched with a directive etchant to form a third film region adjacent to said pattern region, and then said first silicon oxide film and said third silicon nitride film are removed by using said third film region as a mask so as to form said first film region.

Claim 15

The method according to claim 8 wherein at said step (h) a field oxide film is formed, then a recess between said field oxide film and said first silicon nitride film is filled with a filling layer and then etched with a directive etchant to make substantially flat the surface of said silicon substrate.

Claim 16

The method according to claim 8 wherein at said step (g), a first filling material layer is applied onto the entire surface of said silicon substrate for filling a recess defined between inner surfaces of said first silicon nitride film in said deep groove and then said first filling material layer on a flat portion is removed by a directive etchant, thus leaving a portion of said first filling layer in said groove.

Claim 17

The method according to claim 14 wherein at said step (g) after forming said field oxide film, a supplementary filling material layer is applied onto the entire surface of said silicon substrate to fill the supplementary filling material into a recess between said field oxide film and said first filling material layer, and then said field oxide layer and said supplementary filling material layer on said third region are removed to make substantially flat the surface of said silicon substrate.

Claim 18

The method according to claim 7 wherein at said step (a), the surface of said silicon substrate is etched off by about 1/2 of a thickness of a field oxide film to be formed later by using said pattern region as a mask.

Claim 19

The method according to claim 16 wherein at said step (h) a portion of the surface of said silicon substrate at which a field oxide film is to be formed is exposed, the exposed silicon substrate surface is removed by etching by a thickness equal to about 1/2 of a thickness of said field oxide film, and then the exposed silicon substrate surface is oxidized to form said field oxide film.

Claim 20

The method according to claim 7 which further comprises the step of forming a channel cut region at a bottom surface of said groove after forming the same.

Claim 21

The method according to claim 7 wherein at said step (a) a first silicon oxide film and a first silicon nitride film are successively formed on said silicon substrate, a second silicon oxide film is formed on said first silicon nitride film, and a relatively shallow groove is formed through said second silicon oxide film, said first silicon nitride film and said first silicon oxide film; wherein at said step (b) the silicon substrate surface is covered by a second silicon nitride film, and a second film made of polycrystalline silicon, silicon oxide, metal or high molecular weight material is applied onto the silicon substrate and the thickness of said first film is made to be larger than a width of said shallow groove, wherein at said step (g), said second film is etched with a directive etchant so as to leave a second film only at a portion adjacent to said shallow groove and said pattern region, said second silicon nitride film is removed by using said left film as a mask, and the silicon substrate surface is oxidized; wherein at said step (f) the remaining second silicon oxide film and said second silicon nitride film underlying the same are removed, said deep groove is formed in said silicon substrate removed of said second silicon nitride film, said second silicon oxide film and said second silicon nitride film in said shallow groove are removed, and a portion of said silicon substrate at which a field oxide film is to be formed later and a portion of the substrate at a bottom of said shallow groove are etched off by a thickness equal to about 1/2 of a thickness of said field oxide film, and wherein at said step (g) an silicon oxide film and a silicon nitride film preventing oxidation of said silicon oxide film are formed on an inner wall of said shallow groove, said shallow groove is filled with silicon oxide and silicon nitride.