The Type and Solution of Inline Poly Residue Defect for 28 HK Process Improvement

In the high-k advanced semiconductor process, we always use new metals for example AL to replace the NMOS and PMOS poly silicon gate electrodes. The systematic defect of poly residue is a key defect with higher killer ratio in HK process, which will cause chip yield loss or reliability issue. We found that the poly residue closely related to a key parameter of horn height, which is effected by EB1 and EB2 process. More interesting, these processes are related to each other during PREB~ILDO loop, the EBI and EB2 process determined the height of horn, and the CMP process is mainly influenced by the height of the horn. Whether the horn is too high or too low will all cause CMP process loading, and finally result in poly residue defect. Moreover, the PR loading on the different poly CD, leading to the large patch or high poly density place is easy to suffer poly residue defect. Meanwhile, the weak point of CMP process is another factor, which also can easily cause poly residue defect. On the basis of this reason, the root cause of these defects was very intricately. In this study, we discussed every fail model of poly residue defect in depth, and provide effective improvement actions.