Methods of forming gate structures for semiconductor devices using a replacement gate technique and the resulting devices

A method forming a replacement gate structure for a device above a silicon substrate, comprising:

• performing at least one first etching process to remove a sacrificial gate structure positioned between two spaced-apart sidewall spacers so as to thereby define a replacement gate cavity that exposes a surface of said substrate;
• performing a dilute HF acid cleaning process on said exposed surface of said substrate so as to form an H-terminated silicon surface;
• selectively forming a sacrificial alkylsiloxane layer at least on internal surfaces of said sidewall spacers within said replacement gate cavity but not on said H-terminated silicon surface by immersing said device in an alkyltrichlorosilanes (CH3—(CH2)n−1SiCl3) group solution;
• forming a high-k layer of insulating material within said replacement gate cavity above said H-terminated silicon surface and laterally between first spaced-apart portions of said sacrificial alkylsiloxane layer formed on said sidewall spacers;
• forming at least one work-function adjusting metal layer above said high-k layer of insulating material and laterally between second spaced-apart portions of said sacrificial alkylsiloxane layer formed on said sidewall spacers, said at least one work-function adjusting metal having a substantially planar upper surface that extends between said second spaced-apart portions of said sacrificial alkylsiloxane layer formed on said sidewall spacers;
• and
• after forming said at least one work-function adjusting metal layer, removing said sacrificial alkylsiloxane layer.

A method of forming a replacement gate structure for a device above a silicon substrate, comprising:

• performing at least one first etching process to remove a sacrificial gate structure positioned between two spaced-apart sidewall spacers so as to thereby define a replacement gate cavity that exposes a surface of said substrate;
• performing a process operation on said exposed surface of said substrate so as to form an H-terminated silicon surface;
• selectively forming a sacrificial material layer at least on internal surfaces of said sidewall spacers within said replacement gate cavity but not on said H-terminated silicon surface, wherein selectively forming said sacrificial material layer comprises performing a directed self-assembly process to form a self-assembled monolayer of said sacrificial material;
• forming a high-k layer of insulating material within said replacement gate cavity above said H-terminated silicon surface and laterally between first spaced-apart portions of said sacrificial material layer formed on said sidewall spacers;
• and
• forming at least one work-function adjusting metal layer above said high-k layer of insulating material and laterally between second spaced-apart portions of said sacrificial material layer formed on said sidewall spacers, said at least one work-function adjusting metal having a substantially planar upper surface that extends between said second spaced-apart portions of said sacrificial material layer formed on said sidewall spacers.