Direct Shallow Trench Isolation Planarization Technology Research And Application

With the continuous development of semiconductor technology, devices get smaller, so the isolation between the device performance requirements has become more strictly. Into 0.35μm and below technology, LOCOS (Local Oxidation of Silicon) technology cannot meet the requirements of its various limitations, which resulted in a shallow trench isolation (STI) technology. The chemical mechanical planarization (CMP) in semiconductor manufacturing technology is today the formation of shallow trench isolation (STI) of the key technologies. For STI planarization, CMP-based polishing consider different density graphics uniformity, traditional shallow trench isolation planarization (STI CMP) process has been unable to meet the requirements. Direct shallow trench isolation planarization (DSTI CMP) process due to the use of high selectivity of ceria slurry, it has a better chip flatness (Within wafer uniformity) and the smaller the degree of the dishing, thereby it becomes the mainstream technology of 0.18μm level and below the high-end process.This paper describes that chemical mechanical planarization and STI CMP on the basis of the basic principles, through the traditional shallow trench solation planarization and direct shallow trench isolation planarization compared to analyze and explain their advantages and disadvantages, and the necessary of DSTI CMP.As DSTI CMP is based on the use of ceria slurry for the establishment DSTI CMP process, we must firstly select the slurry. We will experiment to compare three different ceria slurries in test wafer polishing performance, and then choose a better performance of the slurry, and this slurry can be used to establish the two-step process in 0.18μm and below DSTI CMP process system. After two-step DSTI CMP process applied to the production line, the wafer surface film thickness is more stable; uniformity is better; the degree of the dish has also been greatly improved, thereby the product yield has been greatly improved. Through the optimal design and applications on polishing endpoint and procedures, the process stability and accuracy improved, technology costs reduced and process capacity increased.