Semiconductor device and manufacturing method of the same
The invention improves the performance of a semiconductor device. A metal silicide film is formed by a silicide process on a gate electrode and an n + -type source region of an LDMOSFET, and no such metal silicide film is formed on an n − -type offset drain region, an n-type offset drain region, and an n + -type drain region. A side wall spacer comprising a silicon film is formed via an insulating film on the side wall of the gate electrode over the drain side thereof, and a field plate electrode is formed by this side wall spacer. The field plate electrode does not extend above the gate electrode, and a metal silicide film is formed over the entire upper surface of the gate electrode in the silicide process.
1. The manufacturing method of a semiconductor device comprising an LDMOSFET having a source region, a drain region, and a gate electrode formed on a main surface of a semiconductor substrate, comprising the steps of:
(a) preparing said semiconductor substrate of a first conductivity type;
(b) forming said gate electrode via a gate insulating film over the main surface of said semiconductor substrate;
(c) forming a first insulating film so as to cover said gate electrode over the main surface of said semiconductor substrate;
(d) forming a first conductor film on said first insulating film; and
(e) forming a field plate electrode with a side wall spacer shape comprising said first conductor film over a side surface of said gate electrode over a side of said drain region by anisotropically etching said first conductor film,
wherein
in said step (e),
a conductor portion with a side wall spacer shape comprising said first conductor film is formed over the side surface of said gate electrode over the side of said source region, and
said manufacturing method further comprising:
(f) after said step (e), removing said conductor portion present over the side surface of said gate electrode over the side of said source region and leaving said field plate electrode on the side surface of said gate electrode on the said of said drain region,
wherein
in said step (a), said semiconductor substrate comprising silicon is prepared,
in said step (b), said gate electrode comprising silicon is formed,
said manufacturing method further comprising, after said step (f), the steps of:
(g) forming a second insulating film so as to cover said gate electrode and said field plate electrode over the main surface of said semiconductor substrate;
(h) forming an etching mask layer on said drain region located over said second insulating film;
(i) removing said second insulating film located over said gate electrode and over said source region and leaving said second insulating film over said drain region by etching using said etching mask layer as an etching mask; and
(j) forming a metal silicide film on said gate electrode and on said source region.
2. The manufacturing method of a semiconductor device according to claim 1 , wherein
said etching mask layer comprises a photoresist layer.
3. The manufacturing method of a semiconductor device according to claim 1 , wherein
in said step (h),
said etching mask layer is formed so that the end portion of said etching mask layer is positioned over said field plate electrode.
4. The manufacturing method of a semiconductor device according to claim 1 , wherein
said step (j) comprises the steps of:
(j1) forming a metal film on said semiconductor substrate above said gate electrode and above said source region;
(j2) forming said metal silicide film by conducting a heat treatment and inducing the reaction of said metal film with the top portion of said gate electrode and top portion of said source region; and
(j3) removing unreacted metal film.
5. The manufacturing method of a semiconductor device according to claim 1 , wherein
said first conductor film comprises a silicon film.