SEMICONDUCTOR DEVICE AND METHOD OF MANUFACTURING THE SAME
A semiconductor device has an insulating film and an n-type buried layer. The insulating film is formed in a flat-shaped cavity formed inside a p-type semiconductor substrate and in a trench extending from a surface of the semiconductor substrate to the cavity. The buried layer is formed in surrounding regions of the cavity and the trench in the semiconductor substrate.
1 . A semiconductor device comprising:
an insulating film formed in a cavity formed inside a semiconductor substrate of a first conductivity type and in a trench extending from a surface of the semiconductor substrate to the cavity; and
a buried layer of a second conductivity type formed in surrounding regions of the cavity and the trench in the semiconductor substrate.
2 . The semiconductor device according to claim 1 , further comprising a diffusion source layer including an impurity of a second conductivity type between the insulating film and the buried layer.
3 . The semiconductor device according to claim 1 , wherein the insulating film includes: an oxide film obtained by oxidizing the semiconductor substrate, the oxide film formed along the inner walls of the cavity and the trench in the semiconductor substrate; and an insulating film formed in the cavity and the trench covered with the oxide film, the insulating film having flowability at the time of film-formation.
4 . The semiconductor device according to claim 1 , further comprising:
a first isolation film extending to a depth of the cavity so as to surround a predetermined region in a cavity forming region in a plane of the semiconductor substrate;
a second isolation film provided near the surface of the semiconductor substrate, the second isolation film being shallower than the first isolation film and separating adjacent regions from each other;
a resurf layer of the second conductivity type formed from the surface of the semiconductor substrate to a depth in a direction toward the buried layer in an element forming region defined by the first isolation film;
a drain region of the second conductivity type formed in the surface of the semiconductor substrate inside the resurf layer;
a source region of the second conductivity type formed in the surface of the semiconductor substrate outside the resurf layer;
a base contact layer of the first conductivity type formed in the surface of the semiconductor substrate outside the resurf layer, the base contact layer being adjacent to the source region; and
a gate electrode provided on the resurf layer between the drain region and the source region with a gate insulating film interposed between the gate electrode and the resurf layer.
5 . The semiconductor device according to claim 2 , wherein the insulating film includes: an oxide film obtained by oxidizing the semiconductor substrate, the oxide film formed along the inner walls of the cavity and the trench in the semiconductor substrate; and an insulating film formed in the cavity and the trench covered with the oxide film, the insulating film having flowability at the time of film-formation.
6 . The semiconductor device according to claim 2 , further comprising:
a first isolation film extending to a depth of the cavity so as to surround a predetermined region in a cavity forming region in a plane of the semiconductor substrate;
a second isolation film provided near the surface of the semiconductor substrate, the second isolation film being shallower than the first isolation film and separating adjacent regions from each other;
a resurf layer of the second conductivity type formed from the surface of the semiconductor substrate to a depth in a direction toward the buried layer in an element forming region defined by the first isolation film;
a drain region of the second conductivity type formed in the surface of the semiconductor substrate inside the resurf layer;
a source region of the second conductivity type formed in the surface of the semiconductor substrate outside the resurf layer;
a base contact layer of the first conductivity type formed in the surface of the semiconductor substrate outside the resurf layer, the base contact layer being adjacent to the source region; and
a gate electrode provided on the resurf layer between the drain region and the source region with a gate insulating film interposed between the gate electrode and the resurf layer.
7 . The semiconductor device according to claim 3 , further comprising:
a first isolation film extending to a depth of the cavity so as to surround a predetermined region in a cavity forming region in a plane of the semiconductor substrate;
a second isolation film provided near the surface of the semiconductor substrate, the second isolation film being shallower than the first isolation film and separating adjacent regions from each other;
a resurf layer of the second conductivity type formed from the surface of the semiconductor substrate to a depth in a direction toward the buried layer in an element forming region defined by the first isolation film;
a drain region of the second conductivity type formed in the surface of the semiconductor substrate inside the resurf layer;
a source region of the second conductivity type formed in the surface of the semiconductor substrate outside the resurf layer;
a base contact layer of the first conductivity type formed in the surface of the semiconductor substrate outside the resurf layer, the base contact layer being adjacent to the source region; and
a gate electrode provided on the resurf layer between the drain region and the source region with a gate insulating film interposed between the gate electrode and the resurf layer.
8 . The semiconductor device according to claim 5 , further comprising:
a first isolation film extending to a depth of the cavity so as to surround a predetermined region in a cavity forming region in a plane of the semiconductor substrate;
a second isolation film provided near the surface of the semiconductor substrate, the second isolation film being shallower than the first isolation film and separating adjacent regions from each other;
a resurf layer of the second conductivity type formed from the surface of the semiconductor substrate to a depth in a direction toward the buried layer in an element forming region defined by the first isolation film;
a drain region of the second conductivity type formed in the surface of the semiconductor substrate inside the resurf layer;
a source region of the second conductivity type formed in the surface of the semiconductor substrate outside the resurf layer;
a base contact layer of the first conductivity type formed in the surface of the semiconductor substrate outside the resurf layer, the base contact layer being adjacent to the source region; and
a gate electrode provided on the resurf layer between the drain region and the source region with a gate insulating film interposed between the gate electrode and the resurf layer.
9 . The semiconductor device according to claim 2 , wherein the diffusion source layer is an AsSG film or a PSG film.
10 . The semiconductor device according to claim 5 , wherein the diffusion source layer is an AsSG film or a PSG film.
11 . The semiconductor device according to claim 6 , wherein the diffusion source layer is an AsSG film or a PSG film.
12 . The semiconductor device according to claim 1 , wherein the cavity is flat-shaped.
13 . The semiconductor device according to claim 3 , wherein the insulating film having flowability at the time of film-formation is a TEOS film.
14 . The semiconductor device according to claim 5 , wherein the insulating film having flowability at the time of film-formation is a TEOS film.
15 . The semiconductor device according to claim 7 , wherein the insulating film having flowability at the time of film-formation is a TEOS film.
16 . The semiconductor device according to claim 8 , wherein the insulating film having flowability at the time of film-formation is a TEOS film.
17 . The semiconductor device according to claim 10 , wherein the insulating film having flowability at the time of film-formation is a TEOS film.
18 . A method of manufacturing a semiconductor device comprising:
forming a cavity in a predetermined depth inside a semiconductor substrate of a first conductivity type;
forming a trench extending from a surface of the semiconductor substrate to the cavity;
forming an impurity diffusion source layer including an impurity of a second conductivity type on inner walls of the cavity and the trench through the trench;
forming an insulating film on the impurity diffusion source layer formed inside the cavity and the trench through the trench; and
forming a buried layer by diffusing the impurity of the second conductivity type included in the impurity diffusion source layer into the semiconductor substrate around the cavity through heat treatment.
19 . The method according to claim 18 , wherein forming the cavity includes forming a plurality of stripe trenches from the surface of the semiconductor substrate to the depth inside the semiconductor substrate and then annealing at high temperature.
20 . The method according to claim 18 , wherein the cavity is flat-shaped.