Method of forming semiconductor device

A method of forming a semiconductor device, comprising:

• providing at least one gate structure on a substrate, wherein the gate structure comprises a first spacer formed on a sidewall of a gate;
• depositing a first disposable spacer material layer on the substrate covering the gate structure;
• etching the first disposable spacer material layer to form a first disposable spacer on the first spacer;
• depositing a second disposable spacer material layer on the substrate covering the gate structure;
• etching the second disposable spacer material layer to form a second disposable spacer on the first disposable spacer;
• removing a portion of the substrate by using the first and second disposable spacers as a mask, so as to form two recesses in the substrate beside the gate structure;
• forming a stress-inducing layer in the recesses;
• removing the first and second disposable spacers;
• forming a second spacer on the first spacer;
• and
• forming two heavily doped regions in the stress-inducing layer beside the gate structure by using the second spacer as a mask.