The resultant surface microscratches due to chemical mechanical polishing (CMP) can cause device failure and reduce production yield in the shallow trench isolation (STI) process. By using a plasma etch process to replace the overpolish step of CMP planarization (CMP+plasma etch), we have reduced 10% of the total defect counts in the 0.15 mum STI process. The CMP microscratches have been effectively smoothened by the additional plasma etch process. The electrical properties of the devices made via the CMP and the CMP+plasma etch processes have been examined and compared. The off-state currents are similar. A higher breakdown voltage is found for the CMP + plasma etch process and can be interpreted by the local electrical-field concentration. Although the n(+)/p and p(+)/n junctions fabricated by the CMP+plasma etch processes exhibit slightly larger leakage currents for certain test patterns, due to plasma damage, the products still meet the inline production requirements, and show promising results for yield improvement. (C) 2003 American Vacuum Society.