Semiconductor device and method for manufacturing thereof
View Patent ↗A semiconductor device and a method for manufacturing the same of forming a silicon nitride film selectively without giving damages or contaminations to a surface of the silicon substrate thereby forming different types of gate dielectrics in one identical silicon substrate, are obtained by forming a silicon dioxide on the surface of a silicon substrate, then removing a portion thereof, forming a silicon nitride film to the surface of the substrate from which the silicon dioxide has been removed and, simultaneously, introducing nitrogen to the surface of the silicon dioxide which is left not being removed or, alternatively, depositing a silicon dioxide on the surface of the silicon substrate by chemical vapor deposition, then removing a portion thereof, forming a silicon nitride film on the surface of a substrate from which the silicon dioxide has been removed, and, simultaneously, introducing nitrogen to the surface of the silicon dioxide left not being removed, successively, dissolving and removing nitrogen-introduced silicon oxide film to expose the surface of the substrate and oxidizing the exposed surface of the silicon substrate and the silicon nitride film.
1. A method for manufacturing a semiconductor device comprising the steps of:
forming a first semiconductor domain and a second semiconductor domain isolated from each other by forming a field dielectric layer for device isolation selectively on a surface of a silicon semiconductor substrate;
forming a silicon dioxide film on each of surfaces of the first semiconductor domain and the second semiconductor domain;
removing the silicon dioxide formed on the surface of the second semiconductor domain for exposing the surface of the second semiconductor domain;
forming a nitrogen-containing silicon oxide film on the surface of the first semiconductor domain and forming a silicon nitride film on the surface of the second semiconductor domain by nitriding the silicon dioxide in the first semiconductor domain, and the exposed surface of the second semiconductor domain;
forming an oxygen-containing silicon nitride film on the surface of the second semiconductor domain by oxidizing the silicon nitride film; and
forming a gate electrode on each of the nitrogen-containing silicon oxide film and the oxygen-containing silicon nitride film;
wherein the thickness of the silicon nitride film before the oxidation in the step of forming the oxygen-containing silicon nitride film is 1.5 nm or less, and an equivalent oxide thickness (EOT) of the oxygen-containing silicon nitride film is 2.5 nm or less.
2. The method for manufacturing a semiconductor device according to claim 1 , wherein the nitridation in the step of forming the nitrogen-containing silicon oxide film in the first semiconductor domain and forming the silicon nitride film in the second semiconductor domain is a heat treatment in an NH 3 -containing atmosphere.
3. The method for manufacturing a semiconductor device according to claim 1 , wherein the nitridation in the step of forming the nitrogen-containing silicon oxide film in the first semiconductor domain and forming the silicon nitride film in the second semiconductor domain is a treatment using nitrogen radicals.
4. The method for manufacturing a semiconductor device according to claim 1 , wherein the oxidation in the step of forming the oxygen-containing silicon nitride film is a heat treatment in an N 2 O-containing atmosphere.
5. The method for manufacturing a semiconductor device according claim 1 , wherein the oxygen concentration of the oxygen-containing silicon nitride film formed in the second semiconductor domain is at a minimum in an intermediate portion of the film between the boundary of the silicon nitride film and the silicon semiconductor substrate, and the surface of the silicon nitride film.