Method for forming self-aligned contact

A method for forming a self-aligned contact, comprising:

• providing a substrate with a transistor thereover, wherein the transistor comprises a mask layer and a pair of insulating spacers formed on opposite sides of the mask layer;
• forming a dielectric layer over the substrate to cover the transistor;
• partially removing the dielectric layer to expose a top portion of the transistor;
• conformally forming a barrier layer over the dielectric layer and the top portion of the transistor;
• etching the barrier layer and leaving a protection barrier over a top corner of the insulating spacers of the transistor;
• performing an etching process to entirely remove the dielectric layer using the protection barrier and the mask layer as an etching mask, thereby forming a self-aligned contact opening exposing a source/drain region of the transistor and a dielectric spacer covered by the protection barrier;
• and
• forming a conductive layer in the self-aligned contact opening to contact the source/drain region of the transistor.