Semiconductor devices and methods of forming the same

A semiconductor device, comprising:

• a semiconductor substrate;
• an isolation feature over the semiconductor substrate;
• a fin protruding from the semiconductor substrate and through the isolation feature;
• a gate structure engaging the fin;
• a sidewall spacer disposed on sidewalls of the gate structure;
• and
• an epitaxial feature over the fin,
• wherein the isolation feature includes a first portion having a first thickness and a second portion having a second thickness that is larger than the first thickness, the first portion is located between the fin and the second portion, and a top surface of the first portion extends continuously to a sidewall of the second portion.

A method of forming a semiconductor device, comprising:

• providing a structure that includes a substrate, a fin protruding from the substrate, an isolation feature surrounding the fin, and a gate structure engaging the fin;
• depositing a resist layer covering the fin, the isolation feature, and the gate structure;
• performing a first etching process to recess the resist layer below a top surface of the gate structure;
• performing a second etching process to further recess the resist layer;
• performing a third etching process to remove the resist layer, wherein the first, second, and third etching processes have different etching rates;
• recessing the fin;
• and
• forming an epitaxial feature above the fin.