Optimization of contact W related processes for 28/22 nm HKMG technology node

We optimize the interlayer buffer (ILB) process to make the contact opening wider, which is beneficial to the subsequent W deposition. The etching profile and the W deposition rate were optimized to improve the gap filling capability for relatively high aspect-ratio contact. Also, we demonstrated that the chemicals employed for wet strip after metal hard mask etching is also crucial for improving the W film quality.