Semiconductor device structure and methods of forming the same

A method, comprising:

• forming an N-type source/drain epitaxial feature over a substrate;
• forming a P-type source/drain epitaxial feature over the substrate;
• selectively depositing a first silicide layer, wherein the first silicide layer comprises a first portion disposed directly on the N-type source/drain epitaxial feature and a second portion disposed directly on the P-type source/drain epitaxial feature, wherein the second portion is substantially thicker than the first portion;
• and
• depositing a second silicide layer, wherein the second silicide layer comprises a third portion disposed directly on the first portion of the first silicide layer and a fourth portion disposed directly on the second portion of the first silicide layer, wherein the third portion is substantially thicker than the fourth portion.

A method, comprising:

• forming an N-type source/drain epitaxial feature over a substrate;
• forming a P-type source/drain epitaxial feature over the substrate;
• performing a first deposition process to simultaneously form a first silicide layer directly on the N-type source/drain epitaxial feature and a second silicide layer directly on the P-type source/drain epitaxial feature, wherein the second silicide layer is substantially thicker than the first silicide layer;
• and
• performing a second deposition process to simultaneously form a third silicide layer directly on the first silicide layer and a fourth silicide layer directly on the second silicide layer, wherein the third silicide layer is substantially thicker than the fourth silicide layer.