HYBRID GATE LAST INTEGRATION SCHEME FOR MULTI-LAYER HIGH-k GATE STACKS

A method of forming a semiconductor device, comprising:

• providing a substrate containing first and second device regions and an interface layer on the substrate;
• depositing a first high-k film on the interface layer in the first and second device regions;
• forming a first cap layer containing a first chemical element on the first high-k film in the first device region;
• forming a second cap layer containing a second chemical element on the high-k film in the second device region, wherein the second chemical element is different from the first chemical element;
• forming an oxygen scavenging layer on the first and second cap layers;
• depositing a replacement gate electrode film in the first and second device regions;
• heat-treating the first high-k film at a first heat-treating temperature to diffuse the first chemical element from the first cap layer into the first high-k film in the first device region to form a first modified high-k film and to diffuse the second chemical element from the second cap layer into the first high-k film in the second device region to form a second modified high-k film, wherein the heat-treating the first high-k film further scavenges oxygen from the interface layer to eliminate or reduce the thickness of the interface layer;
• patterning the replacement gate electrode film in the first and second device regions;
• forming sidewall spacers adjacent the patterned replacement gate electrode film;
• removing the patterned replacement gate electrode film to form recessed features defined by the sidewall spacers in the first and second device regions;
• depositing a second high-k film in the recessed features;
• and
• depositing a gate metal film on the second high-k film.