Methods for forming semiconductor structures using selectively-formed sidewall spacers

A method for forming a FinFET structure, the method comprising the steps of:

• forming a fin overlying a semiconductor substrate;
• forming a gate structure overlying the fin, wherein the gate structure has a height as measured from the semiconductor substrate that is greater than a height of the fin;
• depositing a first sidewall spacer-forming material overlying the gate structure and the fin;
• depositing a second sidewall spacer-forming material overlying the first sidewall spacer-forming material, the second sidewall spacer-forming material having an etch rate when subjected to an etchant that is different from an etch rate of the first sidewall spacer-forming material when subjected to the same etchant;
• etching the second sidewall spacer-forming material and the first sidewall spacer-forming material until a composite spacer is formed about the gate structure;
• at least substantially removing the second sidewall spacer-forming material from the fin;
• and
• at least substantially removing the first sidewall spacer-forming material from the fin.

A method for forming a semiconductor structure, the method comprising the steps of:

• depositing a first sidewall spacer-forming material overlying a first structure and a second structure disposed on a semiconductor structure, the first structure taller than the second structure;
• depositing a second sidewall spacer-forming material overlying the first sidewall spacer-forming material, wherein the second sidewall spacer-forming material is different from the first sidewall spacer-forming material;
• etching the first sidewall spacer-forming material and the second sidewall spacer-forming material until a composite spacer comprising the first sidewall spacer-forming material and the second sidewall spacer-forming material is formed about the first structure and until the second sidewall spacer-forming material is at least substantially removed from the second structure;
• and
• removing the first sidewall spacer-forming material from the first structure.