Semiconductor device and method for fabricating the same
A method for fabricating semiconductor device includes the steps of first forming a gate structure on a substrate, forming a contact etch stop layer (CESL) on the gate structure, forming an interlayer dielectric (ILD) layer around the gate structure, performing a curing process so that an oxygen concentration of the CESL is different from the oxygen concentration of the ILD layer, and then performing a replacement metal gate process (RMG) process to transform the gate structure into a metal gate.
1. A method for fabricating semiconductor device, comprising:
forming a gate structure on a substrate;
forming a contact etch stop layer (CESL) on the gate structure;
forming an interlayer dielectric (ILD) layer around the gate structure;
performing a curing process while the CESL is on the gate structure; and
performing a replacement metal gate process (RMG) process to transform the gate structure into a metal gate.
2. The method of claim 1 , further comprising:
forming the ILD layer on the CESL;
performing the curing process so that an oxygen concentration in the CESL and an oxygen concentration in the ILD layer are different.
3. The method of claim 2 , wherein the oxygen concentration in the ILD layer is greater than the oxygen concentration in the CESL.
4. The method of claim 2 , wherein the oxygen concentration on a surface of the CESL is greater than the oxygen concentration in the CESL.
5. The method of claim 1 , further comprising performing the curing process so that the CESL and the ILD layer comprise same dielectric constant.
6. The method of claim 1 , further comprising forming a spacer around the gate structure, wherein the spacer comprises an offset spacer and a main spacer.
7. The method of claim 6 , further comprising performing the curing process so that the main spacer, the CESL, and the ILD layer comprise same dielectric constant.
8. The method of claim 1 , further comprising:
performing a planarizing process to remove part of the ILD layer; and
performing the RMG process.
9. The method of claim 1 , wherein a temperature of the curing process is between 500° C. to 800° C.
10. The method of claim 1 , wherein a duration of the curing process is between 50 minutes to 70 minutes.