Semiconductor device having transistors each having gate electrode of different metal ratio and production process thereof
View Patent ↗A semiconductor device with integrated MIS field-effect transistors includes a first transistor containing a first gate electrode having a composition represented by MAx and a second transistor containing a second gate electrode having a composition represented by MAy, wherein M is at least one metal element selected from the group consisting of W, Mo, Ni, Pt, Ta, Pd, Co and Ti; A is silicon and/or germanium; 0<x≦3 and 0<y≦3, and x and y are different from each other.
1. A process of producing a semiconductor device, said process comprising:
forming an isolation film on a semiconductor substrate;
introducing an impurity into surfaces of a plurality of active device regions isolated by the isolation film;
forming a gate-insulating film in each of the active device regions;
forming a polycrystalline film on the gate-insulating film, and selectively etching the polycrystalline film to form a plurality of gate electrodes;
forming source-drain regions with the polycrystalline film placed therebetween;
selectively forming, on a surface of a source-drain region, an electroconductive film of a metal semiconductor compound containing an element of the polycrystalline film;
forming an interlayer insulation film which covers the polycrystalline film and the electroconductive film;
selectively removing the interlayer insulation film to expose an upper side of the polycrystalline film;
forming a metallic film on the exposed upper side of the polycrystalline film;
reacting the polycrystalline film with the metallic film under heating to form a plurality of gate electrodes of a metal semiconductor compound containing an element constituting the metallic film and an element constituting the polycrystalline film;
selectively disposing a film of a same element as that constituting the polycrystalline film on a gate electrode of the plurality of gate electrodes;
reacting the gate electrodes with the selectively disposed film of the element under heating, to reduce a compositional metal ratio in the gate electrodes, and
selectively removing the films of the element remaining unreacted,
wherein the element which constitutes the polycrystalline film comprises silicon or germanium.
2. The process according to claim 1 , further comprising selectively reducing a thickness of at least one polycrystalline film to form a polycrystalline film of a different thickness after exposing the upper side of the polycrystalline film and before forming the metallic film on the exposed polycrystalline film.
3. The process according to claim 1 , wherein the element which constitutes the polycrystalline film comprises silicon.