Method of manufacturing a semiconductor device having silicon islands

A method of manufacturing a semiconductor memory device comprising:

• a first step of growing a first silicon oxide film on a silicon substrate and depositing a first silicon nitride film thereon;
• a second step of etching said first silicon nitride film, said first silicon oxide film and said silicon substrate by employing a resist pattern as a mask to form a silicon island comprised of a part of said silicon substrate, leaving a remaining part of the silicon substrate;
• a third step of growing a second silicon oxide film on a surface of said silicon substrate exposed by said second step and on a surface of said silicon island, depositing a second silicon nitride film thereon, and etching said second silicon nitride film so as to leave a portion of said second silicon nitride film deposited on a side wall of said silicon island;
• a fourth step of growing a third silicon oxide film between the remaining part of the silicon substrate and the silicon island, by thermal oxidation of the surface of said silicon substrate, to thereby grow a silicon oxide layer between the remaining part of the silicon substrate and the silicon island, to separate electrically said silicon island from said remaining part of the silicon substrate;
• a fifth step of forming a gate electrode on said silicon island, said gate electrode being formed on upper and side surfaces of the silicon island, and forming a source region and a drain region in said silicon island by employing said gate electrode as a mask;
• and
• a sixth step of forming a plate electrode on said source region through an insulating film.

A method of manufacturing an insulated gate field effect transistor comprising:

• a first step of growing a first silicon oxide film on a silicon substrate and depositing a first silicon nitride film thereon;
• a second step of etching said first silicon nitride film, said first oxide film and said silicon substrate by employing a resist pattern as a mask to form a silicon island comprised of a part of said silicon substrate, leaving a remaining part of the silicon substrate;
• a third step of growing a second silicon oxide film on a surface of said silicon substrate exposed by said second step and on a surface of said silicon island, depositing a second silicon nitride film thereon, and etching said second silicon nitride film so as to leave a portion of said second silicon nitride film deposited on a side wall of said silicon island;
• and
• a fourth step of forming a gate electrode of the transistor on said silicon island, said gate electrode being formed on upper and side surfaces of the silicon island at which said transistor is formed, and forming a source region and a drain region in said silicon island by employing said gate electrode as a mask.

A method of manufacturing a semiconductor memory device comprising:

• a first step of growing a first silicon oxide film on a silicon substrate and depositing a first silicon nitride film thereon;
• a second step of etching said first silicon nitride film, said first silicon oxide film and said silicon substrate by employing a resist pattern as a mask to form a silicon island comprised of a part of said silicon substrate, leaving a remaining part of the silicon substrate;
• a third step of growing a second silicon oxide film on a surface of said silicon substrate exposed by said second step and on a surface of said silicon island, depositing a second silicon nitride film thereon, and etching said second silicon nitride film so as to leave a portion of said second silicon nitride film deposited on a side wall of said silicon island;
• a fourth step of forming a gate electrode of a transistor on said silicon island, said gate electrode being formed on upper and side surfaces of the silicon island at which said transistor is formed, and forming a source region and a drain region in said silicon island by employing said gate electrode as a mask;
• and
• a fifth step of forming a plate electrode on said source region with an insulating film interposed between the plate electrode and the source region.

A method of manufacturing a semiconductor device, comprising the steps of:

• (a) providing a silicon substrate having projections of silicon extending from a surface thereof, a remaining portion of the silicon substrate not having the projections extending from the surface thereof, the projections respectively forming silicon islands;
• (b) after step (a), forming a silicon oxide film between the silicon islands, on the remaining portion of the silicon substrate, the silicon oxide film extending beneath the silicon islands;
• (c) forming gate electrodes on said silicon islands, said gate electrodes being formed on upper and side surfaces of the silicon islands, the gate electrodes being gate electrodes of transistors;
• and
• (d) forming impurity-doped semiconductor regions of the semiconductor device in the silicon islands by employing said gate electrodes as masks, the semiconductor regions being regions of semiconductor elements of the semiconductor device.