Methods of using a metal protection layer to form replacement gate structures for semiconductor devices

A method of forming replacement gate structures above a substrate, the method comprising:

• forming first and second replacement gate cavities above said substrate for first and second transistor devices, respectively, said first transistor device having a channel length of less than 40 nm, said second transistor device having a channel length that is greater than 40 nm;
• forming a high-k gate insulation layer in said first and second replacement gate cavities;
• forming a work-function adjusting metal layer in said first and second replacement gate cavities above said high-k gate insulation layer;
• forming a metal protection layer above said work-function adjusting layer in said first and second replacement gate cavities, said metal protection layer being formed so as to pinch-off said first replacement gate cavity while leaving a portion of said second replacement gate cavity un-filled;
• forming a first bulk conductive metal layer such that it is positioned within said un-filled portion of said second replacement gate cavity above said metal protection layer while said first replacement gate cavity is substantially free of said first bulk conductive metal layer;
• performing at least one first recess etching process to remove portions of a sidewall spacer and portions of said high-k gate insulation layer positioned within or adjacent said first and second replacement gate cavities;
• performing at least one second recess etching process to selectively remove portions of said work-function adjusting metal layer selectively relative to at least said high-k gate insulation layer and said metal protection layer within said first and second replacement gate cavities;
• performing at least one third recess etching process to selectively remove substantially all of said metal protection layer in said first replacement gate cavity while leaving a portion of said metal protection layer in said second replacement gate cavity;
• forming a second bulk conductive metal layer within said first and second replacement gate cavities;
• performing at least one recess etching process to recess said second bulk conductive metal layer within said first replacement gate cavity and to recess said second bulk conductive metal layer and said first bulk metal conductive layer within said second replacement gate cavity so as to define first and second gate-cap cavities in said first and second replacement gate cavities, respectively;
• and
• forming gate cap layers within said first and second gate-cap cavities.

A method of forming a replacement gate structure above a substrate, the method comprising:

• forming a replacement gate cavity above said substrate;
• forming a high-k gate insulation layer in said replacement gate cavity;
• forming a work-function adjusting metal layer in said replacement gate cavity above said high-k gate insulation layer;
• forming a sacrificial metal protection layer above said work-function adjusting layer in said replacement gate cavity, said sacrificial metal protection layer being formed so as to pinch-off said replacement gate cavity;
• performing at least one etching process to selectively remove substantially all of said sacrificial metal protection layer in said replacement gate cavity;
• after selectively removing substantially all of said sacrificial metal protection layer from said replacement gate cavity, forming a bulk conductive metal layer within said replacement gate cavity;
• performing at least one recess etching process to recess said bulk conductive metal layer within said replacement gate cavity so as to define a gate-cap cavity within said replacement gate cavity;
• and
• forming a gate cap layer within said replacement gate cavity.

A method of forming a replacement gate structure above a substrate, the method comprising:

• forming a replacement gate cavity above said substrate;
• forming a high-k gate insulation layer in said replacement gate cavity;
• forming a work-function adjusting metal layer in said replacement gate cavity above said high-k gate insulation layer;
• forming a metal protection layer above said work-function adjusting layer in said replacement gate cavity;
• forming a first bulk conductive metal layer in said replacement gate cavity above said metal protection layer;
• after forming said first bulk conductive metal layer, performing at least one etching process to selectively remove a portion, but not all, of said metal protection layer in said replacement gate cavity;
• forming a second bulk conductive metal layer within said replacement gate cavity;
• performing at least one recess etching process to recess said second bulk conductive metal layer and said first bulk metal conductive layer within said replacement gate cavity so as to define a gate-cap cavity in said replacement gate cavity;
• and
• forming a gate cap layer within said gate-cap cavity.