Method for producing a solid-state imaging element
View Patent ↗There is provided a solid-state imaging element having a light receiving part generating charges by light irradiation, and a source/drain region of a transistor, both formed in a semiconductor layer. The solid-state imaging element includes a non-silicided region including the light receiving part, in which surfaces of the source/drain region and a gate electrode of the transistor are not silicided; and a silicided region in which the surfaces of the source/drain region and the gate electrode of the transistor are silicided. The non-silicided region has a sidewall formed on a side surface of the gate electrode of the transistor, a hydrogen supply film formed to cover the semiconductor layer, the gate electrode, and the sidewall, and a salicide block film formed on the hydrogen supply film to prevent silicidation. The silicided region has a sidewall formed on the side surface of the gate electrode of the transistor.
1. A method for producing a solid-state imaging element having a silicided region including a transistor in which surfaces of a source/drain region and a gate electrode of the transistor are at least silicided; and a non-silicided region including a transistor in which surfaces of the source/drain region and the gate electrode of the transistor are not silicided, the method comprising the steps of:
forming a gate electrode on a semiconductor layer in each region;
forming an insulating film to cover the semiconductor layer and each gate electrode, the step of forming the insulating film to cover each gate electrode comprises the step of forming a silicon oxide film to cover each gate electrode and forming a silicon nitride film on the silicon oxide film;
etching the insulating film to form a sidewall on a side surface of the gate electrode;
forming each source/drain region in the semiconductor layer using each gate electrode and each sidewall as masks;
forming a hydrogen supply film to cover the gate electrodes, the sidewalls, the source/drain regions, and a light receiving region formed in the semiconductor layer to generate charges by light irradiation;
forming a salicide block film on the hydrogen supply film;
removing the hydrogen supply film and the salicide block film except for the non-silicided region; and
forming a metal silicide film by forming a metal film on a substrate and then thermally treating the metal film to silicide an upper part of the gate electrode and an upper part of the source/drain region in the silicided region based on reaction of the metal film with silicon.
2. A method for producing a solid-state imaging element according to claim 1 , further comprising the step of forming a silicon oxide film to cover each gate electrode and forming a silicon nitride film on the silicon oxide film in the step of forming the insulating film to cover each gate electrode.
3. A method for producing a solid-state imaging element according to claim 1 , further comprising the step of etching the insulating film in the silicided region and the non-silicided region to form each sidewall having an identical structure in each of the silicided region and the non-silicided region.
4. A method for producing a solid-state imaging element according to claim 1 , further comprising the step of performing source/drain injection into the silicided region and the non-silicided region under identical conditions in the step of forming each source/drain region.
5. A method for producing a solid-state imaging element according to claim 1 , further comprising the step of forming the hydrogen supply film by a silicon nitride film deposited by plasma CVD using an ultraviolet light source.
6. A method for producing a solid-state imaging element according to claim 1 , further comprising the step of forming the salicide block film by an SiN film formed by low pressure CVD.