A NOVEL PLANARIZATION OF OXIDE-FILLED SHALLOW-TRENCH ISOLATION

Two planarization approaches of the oxide-filled trench isolation have been evaluated. Results show that the oxide-filled shallow-trench iso lation technology based on a chemical-mechanical polishing (CMP) proce ss is difficult to control and has a poor uniformity. It also results in a dishing effect in wide field regions. On the other hand, a new pl anarization process can achieve an excellent uniformity and fully plan ar surface by using a combination of a masking polysilicon layer based on a CMP process, selective wet etching for oxide refill on active re gions, short-time CMP process for oxide refill, and reactive ion etchi ng etchback. Results also show that the high breakdown yield of the ga te oxide and the low leakage current of the n(+)/p junction diodes wit h the novel planarization process demonstrates extremely low defect de nsity from this process. This new process is a very promising candidat e for oxide-filled shallow-trench isolation.