Key Tecnology Of 0.15um Lithography

In the recent twenty years, IC technology made a huge progress. The integration keep on increasing following Moore’s law: the number of transistors that can be placed inexpensively on anintegrated circuit doubles approximately every two years (or 18 months). With the integration turns higher and higher, lithography meets more and more trouble. Such as the optical parameter setting, the film flatness, the reflected light and resist thickness uniformity, which have direct relationship with the successful image transfer.This paper intraduces the basic lithography process, including resist coating, exposure, developer, Overlay and Critical Demetion inline check. With the traditional optical, 248nm KrF scanner can get the best CD which is 0.18um only. So if want to make a 0.15un CD possible, more auxiliary technology is required. This paper also introduces the technology such as the OAI which can improve resolution, PSM which can improve the contrast, OPC that can improve IC reliability, BARC resist which is used to reduce the reflection.Because of the impact of wafer surface emissivity and flatness by each process of the whole flow, the lithography process window is narrow. The wafer alwayer suffer low yield issue, especially at wafer edge which caused by the film flatness gap. It is the first killer of yield and hard to be solved.This paper takes a production which suffer wafer edge low yield as example, after doing failure analysis in detail using IV cure and OBIRCH, studying the method of detecting surface flatness and the SMS compensation arithmetic deeply, get a efficient wafer edge defocus solution which improve yield much.