Semiconductor device and its manufacturing method
A semiconductor device manufacturing method includes, forming isolation region having an aspect ratio of 1 or more in a semiconductor substrate, forming a gate insulating film, forming a silicon gate electrode and a silicon resistive element, forming side wall spacers on the gate electrode, heavily doping a first active region with phosphorus and a second active region and the resistive element with p-type impurities by ion implantation, forming salicide block at 500° C. or lower, depositing a metal layer covering the salicide block, and selectively forming metal silicide layers. The method may further includes, forming a thick and a thin gate insulating films, and performing implantation of ions of a first conductivity type not penetrating the thick gate insulating film and oblique implantation of ions of the opposite conductivity type penetrating also the thick gate insulating film before the formation of side wall spacers.
1. A semiconductor device comprising:
a semiconductor substrate;
a first active region of a first conductivity type formed in said semiconductor substrate;
a second active region of a second conductivity type formed in said semiconductor substrate;
a first gate insulating film having a first thickness, and formed on said first active region;
a second gate insulating film having a second thickness thinner than the first thickness, and formed on said second active region;
first and second gate electrodes formed on the first and second gate insulating films, respectively;
side wall spacers of insulating material formed on side walls of said first and second gate electrodes;
a first diffusion region of the second conductivity type formed in said first active region outside and aligned with the edge of said side wall spacers;
a second diffusion region of the first conductivity type formed in said second active region outside and aligned with the edge of said side wall spacers;
a third diffusion region of the second conductivity type having an impurity concentration lower than that of said first diffusion region, and formed in said first active region outside and aligned with the edge of said first gate electrode;
a fourth diffusion region of the second conductivity type formed in said second active region outside and aligned with the edge of said second gate electrode, and having an impurity concentration higher than that of said second active region; and
a fifth diffusion region of the first conductivity type formed in said second active region and within said fourth diffusion region outside and aligned with the edge of said second gate electrode, and having an impurity concentration lower than that of said second diffusion region;
wherein said gate insulating films extend under said side wall spacers and do not extend outside the sidewall spacers, and the impurity concentration distributions of said third diffusion region is substantially equal to that of said fourth diffusion region.
2. The semiconductor device according to claim 1 , wherein said third diffusion region of the second conductivity type has an impurity concentration gradient along a horizontal direction, in an area from under said first gate electrode, and via an end of said first gate electrode, to under said side wall spacers.
3. The semiconductor device according to claim 1 , wherein the first thickness is five times or more the second thickness.
4. The semiconductor device according to claim 1 , further comprising:
a third active region of the second conductivity type formed in said semiconductor substrate;
a fourth active region of the first conductivity type formed in said semiconductor substrate;
a third gate insulating film having the first thickness, and formed on said third active region;
a fourth gate insulating film having the second thickness, and formed on said fourth active region;
third and fourth gate electrodes formed on the third and fourth gate insulating films, respectively;
side wall spacers of insulating material formed on side walls of said third and fourth gate electrodes;
a sixth diffusion region of the first conductivity type formed in said third active region outside and aligned with the edge of said side wall spacers;
a seventh diffusion region of the second conductivity type formed in said fourth active region outside and aligned with the edge of said side wall spacers;
an eighth diffusion region of the first conductivity type having an impurity concentration lower than that of said sixth diffusion region, and formed in said third active region outside and aligned with the edge of said third gate electrode;
a ninth diffusion region of the first conductivity type formed in said fourth active region outside and aligned with the edge of said fourth gate electrode, and having an impurity concentration higher than said fourth active region; and
a tenth diffusion region of the second conductivity type formed in said fourth active region outside and aligned with the edge of said fourth gate electrodes,
wherein the impurity concentration distribution in said eighth diffusion region is substantially equal to that of said ninth diffusion region.
5. The semiconductor device according to claim 4 , wherein said eighth diffusion region of the first conductivity type has an impurity concentration gradient along a horizontal direction, in an area from under said third gate electrode, via under an end of said third gate electrode, to under said side wall spacer.