Modeling and Control of Chemical Mechanical Polishing (2/3)
Date Issued
2003
Date
2003
Author(s)
余政靖
DOI
912214E002036
Abstract
In this work, an analogy between the soft landing of a spacecraft and CMP operation is established and, subsequently, a polishing strategy is proposed. The objective of soft landing is to minimize the landing time, a minimum time problem, while ensure a safe landing without damaging the vehicle. A similar situation is encountered in the operation of CMP. Despite recent advances in copper (Cu) CMP technology, it still suffers pattern dependence that results in large variation across the wafer. Much of the past research focuses on the effects of pattern geometry on the interlevel dielectric (ILD) layer. Nonetheless, the semi-physical pattern dependent model can be extended directly to the copper removal. In this work, the model of Boning and co-workers is extended to Cu CMP by taking the pattern geometry into account. Finally, the pattern dependent model is extended to the over-polish stage. Therefore, an optimal operation strategy can be derived to achieve prescribed dishing limit while maintaining a high throughput with minimal ECP Cu thickness. This is achieved by selecting an optimal final step height in the planarization stage and devising the over-polishing trajectory. Again, practical considerations lead to the discretization of the continuous trajectory into finite stages, a sub-optimal control law.
Publisher
臺北市：國立臺灣大學化學工程學系暨研究所
Type
report
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