The Investigation and Detection of Poly Residue Defect for 28 HKMG Process

In the 28 high-k advanced semiconductor process, we always use new metals for example AL to replace the NMOS and PMOS poly silicon gate electrodes. It needs to metal deposition into the poly groove which requires metal filling coverage, but also required no residue and block. The poly residue is a key defect in the 28HK process, will cause the loss of the final chip yield and reliability issue. We found that the poly residue closely related to a key parameter of horn height. More interesting, Whether the horn is too high or too low will finally result in poly residue defect. so the root causes of poly residue was very intricately . In this study, we discussed every fail model of poly residue defect in depth, and provide effective improvement actions. Summary proposes effective improvement methods to improve factory yield.