A Multi-scale Model for Copper Dishing in Chemical-Mechanical Polishing
Name
IMST016.pdf
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372.55 KB
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Adobe PDF
Checksum (MD5)
3465d441f186eb9f19ce60c132dc8c6e
Author(s)
Noh, Kyungyoon
Saka, Nannaji
Chun, Jung-Hoon
Date Issued
January 2005
Series/Report no.
Innovation in Manufacturing Systems and Technology (IMST);
Abstract
The present success in the manufacture of multi-layer interconnects in ultra-large-scale integration is largely due to the acceptable planarization capabilities of the chemical-mechanical polishing (CMP) process. In the past decade, copper has emerged as the preferred interconnect material. The greatest challenge in Cu CMP at present is the control of wafer surface non-uniformity at various scales. As the size of a wafer has increased to 300 mm, the wafer-level non-uniformity has assumed critical importance. Moreover, the pattern geometry in each die has become quite complex due to a wide range of feature sizes and multi-level structures. Therefore, it is important to develop a non-uniformity model that integrates
wafer-, die- and feature-level variations into a unified, multi-scale dielectric erosion and Cu dishing model. In this paper, a systematic way of characterizing and modeling dishing in the single-step Cu CMP process is presented. The possible causes of dishing at each scale are identified in terms of several geometric and process parameters. The feature-scale pressure calculation based on the step-height at each polishing stage is introduced. The dishing model is based on pad elastic deformation and the evolving pattern geometry, and is integrated with the wafer- and die-level variations. Experimental and analytical means of determining the model parameters are outlined and the model is validated by polishing experiments on patterned wafers. Finally, practical approaches for minimizing Cu dishing are suggested.
Subjects
Chemical mechanical polishing
Cu dishing
Semiconductor manufacturing
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