Semiconductor device having STI without divot and its manufacture
The method of manufacturing a semiconductor device has the steps of: etching a semiconductor substrate to form an isolation trench by using as a mask a pattern including a first silicon nitride film and having a window; depositing a second silicon nitride film covering an inner surface of the isolation trench; forming a first silicon oxide film burying the isolation trench; etching and removing the first silicon oxide film in an upper region of the isolation trench; etching and removing the exposed second silicon nitride film; chemical-mechanical-polishing the second silicon oxide film; and etching and removing the exposed first silicon nitride film.
1. A semiconductor device comprising:
a semiconductor substrate;
an isolation trench formed under a surface of said semiconductor substrate;
a liner of a silicon nitride film covering a lower inner surface of said isolation trench, wherein said liner of a silicon nitride film is retracted below the surface of said semiconductor substrate;
a first silicon oxide film formed in a region surrounded by said liner of the silicon nitride film and burying a lower region of said isolation trench;
a second silicon oxide film formed on said first silicon oxide film and burying an upper region of said isolation trench; and
active regions defined by said isolation trench;
wherein said first silicon oxide film and said second silicon oxide film are in direct contact with said silicon nitride film.
2. The semiconductor device according to claim 1 , wherein said liner of the silicon nitride film is retracted below the surface of said semiconductor substrate by 80 nm to 150 nm.
3. The semiconductor device according to claim 1 , wherein said liner of the silicon nitride film has a thickness of 20 nm to 40 nm.
4. The semiconductor device according to claim 1 , wherein said second silicon oxide film extends over a corner and to an upper surface of said active region.
5. The semiconductor device according to claim 1 , wherein a width of said isolation trench is 100 nm or narrower.
6. A semiconductor device comprising:
a semiconductor substrate;
an isolation trench formed under a surface of said semiconductor substrate;
a liner of a silicon nitride film covering a lower inner surface of said isolation trench; wherein said liner of a silicon nitride film is retracted below the surface of said semiconductor substrate;
a first silicon oxide film formed in a region surrounded by said liner of the silicon nitride film and burying a lower region of said isolation trench;
a second silicon oxide film formed on said first silicon oxide film and burying an upper region of said isolation trench;
active regions defined by said isolation trench; and
wherein said liner of the silicon nitride film is retracted below the surface of said semiconductor substrate by 80 nm to 150 nm and exerts a tensile stress.
7. A semiconductor device comprising:
a semiconductor substrate;
a isolation trench formed under a surface of said semiconductor substrate;
a liner of a silicon nitride film covering a lower inner surface of said isolation trench; wherein said liner of a silicon nitride film is retracted below the surface of said semiconductor substrate;
a first silicon oxide film formed in a region surrounded by said liner of the silicon nitride film and burying a lower region of said isolation trench;
a second silicon oxide film formed on said first silicon oxide film and burying an upper region of said isolation trench;
active regions defined by said isolation trench; and
wherein said second silicon oxide film extends over a corner and to an upper surface of said active region.