In-situ process monitoring and orientation effects-based pattern design for chemical mechanical planarization

Chemical Mechanical Planarization(CMP) has become the de facto standard process to achieve global planarization for logic and DRAM devices with feature sizes in the sub-micron range. The International Technology Roadmap for Semiconductors (ITRS), however, has identified a number of issues related to CMP as "roadblocks" for the 65 nm technology node and beyond because of formidable challenges ahead for CMP technology.; In this dissertation, three different parts of the CMP process were studied in order to effectively address the challenges.; The first part of this dissertation examined in-situ process monitoring in the CMP process.; To study material removal mechanisms of oxide CMP, a series of scratch test were conducted on pre- and post-CMP processed wafers with acoustic emission (AE) as a monitoring tool. The analysis of AE signals confirms three distinct layers.; AE was also introduced as a new approach to end-point detection in the CMP process and proved to be feasible with the copper damascene process and the shallow trench isolation process. The relationship between the hardness and AE signals of a material was discussed.; The second part of this dissertation suggested a new polishing pad design applicable at the 65nm technology node and beyond.; Currently used pads were investigated, and the scale effects in the CMP process were identified to suggest a new concept polishing pad that can go beyond the 65 nm technology node.; The last part of this dissertation studied the orientation effects in shape evolution in the CMP process and proposed design rules for CMP-compatible alignment marks.; By introducing the uni-directional polishing concept, the orientation effects in shape evolution that are lost in conventional polishing were recognized. 1D features and 2D features were polished in both conventional and uni-directional modes, and the profiles across edges were analyzed.; And the effect of CMP on the overlay errors were also analyzed in terms of shape evolution. Two case studies using concave and convex alignment marks were performed to investigate the effect of CMP on the overlay errors.