Method for manufacturing semiconductor device
View Patent ↗A semiconductor device includes an element isolation film, which exhibits less variations in the height dimension from the surface of the substrate and has a desired height dimension from the surface of the substrate. A process for manufacturing a semiconductor device includes: providing a predetermined pattern of a silicon nitride film and a protective film which covers the silicon nitride film, on a semiconductor substrate; selectively etching the semiconductor substrate using the protective film as a mask to form a trenched portion; removing the protective film to expose the silicon nitride film; depositing an element isolation film, so as to fill the trenched portion therewith and cover the silicon nitride film; removing the element isolation film formed on the silicon nitride film by polishing thereof until the silicon nitride film is exposed; and removing the silicon nitride film.
1. A method for manufacturing a semiconductor device, comprising:
providing a predetermined pattern of a silicon nitride film and an amorphous carbon protective film which covers the silicon nitride film on a silicon semiconductor substrate;
selectively etching the semiconductor substrate using said amorphous carbon protective film as a mask to form a trenched portion, the trenched portion being formed via an etch process using an etchant gas under a condition in which an etch selectivity is represented by a ratio:
(an etch rate of said silicon semiconductor substrate)/(an etch rate of said amorphous carbon protective film) is equal to or higher than 5;
removing said amorphous carbon protective film to expose said silicon nitride film;
depositing an element isolation film so as to fill said trenched portion therewith and cover said silicon nitride film;
removing the element isolation film formed on said silicon nitride film by polishing thereof until said silicon nitride film is exposed; and
removing said silicon nitride film.
2. The method for manufacturing the semiconductor device according to claim 1 , wherein said amorphous carbon protective film is formed via a chemical vapor deposition (CVD) process, and wherein in said removing said protective film, said protective film is removed via an ashing process employing oxygen gas as an ashing gas.
3. The method for manufacturing the semiconductor device according to claim 1 , wherein said providing a predetermined pattern of a silicon nitride film and a protective film which covers the silicon nitride film over a semiconductor substrate comprises:
depositing said silicon nitride film and said amorphous carbon protective film which covers the silicon nitride film on said semiconductor substrate;
depositing an inorganic film on said amorphous carbon protective film wherein said inorganic film is a SiOC film, a SiON film or a SiO 2 film;
providing a mask having a predetermined pattern by applying a resist on said inorganic film;
selectively removing said inorganic film to form a predetermined pattern;
removing said resist and selectively removing said amorphous carbon protective film using said inorganic film as a mask to form a predetermined pattern of said protective film; and
removing said inorganic film, and selectively removing said silicon nitride film using said amorphous carbon protective film as a mask to form a predetermined pattern of said silicon nitride film.
4. The method for manufacturing the semiconductor device according to claim 3 , wherein a ratio of oxygen radical dry etch rate for the amorphous carbon protective film/etch rate of the inorganic film is equal to or greater than 10.
5. The method for manufacturing the semiconductor device according to claim 3 , wherein a ratio of oxygen radical dry etch rate for the amorphous carbon protective film/etch rate of the inorganic film is equal to or greater than 20.
6. The method for manufacturing the semiconductor device according to claim 3 , wherein the inorganic film and the amorphous carbon protective film form an anti-reflection film.
7. The method for manufacturing the semiconductor device according to claim 1 , wherein when removing the silicon nitride film, a ratio of dry etch rate for the silicon nitride film/amorphous carbon protective film/etch rate of the inorganic film is equal to or greater than 3.
8. The method for manufacturing the semiconductor device according to claim 1 , wherein when removing the amorphous carbon protective film, a ratio of dry etch ashing etch rate for amorphous carbon film/etch rate of silicon nitride film is equal to or greater than 20.
9. The method for manufacturing the semiconductor device according to claim 1 , wherein when removing the amorphous carbon protective film, a ratio of dry etch ashing etch rate for amorphous carbon film/etch rate of silicon nitride film is equal to or greater than 100.
10. The method for manufacturing the semiconductor device according to claim 1 , wherein the silicon nitride film has a thickness of 50-150 nm.
11. The method for manufacturing the semiconductor device according to claim 1 , wherein the amorphous carbon protective film has a thickness of 50-150 nm.
12. The method for manufacturing the semiconductor device according to claim 1 , wherein the amorphous carbon protective film is formed directly on the silicon nitride film.
13. The method for manufacturing the semiconductor device according to claim 1 , wherein the etchant gas is a mixture of halogen-containing gas and at least one of O 2 , N 2 or He.
14. The method for manufacturing the semiconductor device according to claim 1 , wherein the halogen-containing gas is selected from Br 2 , Cl 2 or SF 6 .