Effect of CMP process on alignment accuracy

In this paper, experimental results on alignment accuracy in STI (Shallow Trench Isolation) CMP (Chemical Mechanical Polishing) process is presented. The effect of alignment mark tone with sampling number on alignment accuracy is described for various CMP conditions. Our preliminary results show that alignment accuracy of concave alignment mark is better than convex alignment mark and CMP polishing uniformity affects the alignment accuracy in the case of over polishing.