Novel approach of UV cross- link process for advanced planarization technology in 32 - 45 nm lithography

摘要

Conventional method of patterning trenches in a via first trench last Dual Damascene process involves filling the thickness bias with thermal cross-link gap fill material and then applying the photoresist followed by trench lithography. The major problem of this process is the large thickness bias (step height) observed as the via pattern pitch and density changes across the wafer. Now, the new approach of UV cross-link system instead of thermal cross-link gap fillrnmaterial is proposed. The material is referred to as UV cross-link film ( XUV~TM ) . The main properties of UV cross-link film are small thickness bias of blanket field and dense-via pattern, high planarization, and void free by using the newest UV cross link process that we studied in UV-photo irradiation system. The process for UV cross-link film is very simple, just UV ray irradiate the film for about 10 s in the same coater-developer tool. In this paper, we study the novel approach, UV cross-link process for reducing the thickness bias. The planarization of XUV~TM was very high as compared with that of the film obtained from thermal cross-link gap fill material as the reference. The application of UV cross- link process using XUV~TM is one of the most promising processes ready to be investigated into mass production to leave out the dry etch back process before patterning trench in via first trench last Dual Damascene lithography.