Abstract
Within wafer non-uniformity (WIWNU), which significantly affects the yield of chip products, is mainly caused by non-uniform chemical mechanical polishing (CMP) at the wafer’s edge. This study investigates the origins of the non-uniformity and presents a process that uses an edge profile control ring (EPC ring) to solve the problem. The EPC ring is designed to be positioned between the wafer and the retaining ring and pressed at the same pressure as the wafer by a flexible membrane to reduce the pressure discontinuity between the center region and the edge region of the wafer. Experimental results show that for a WIWNU of 2%, the EPC ring makes it possible to shrink the edge exclusion region from 15 mm to 2 mm without any change in process conditions. This result suggests that the EPC ring is applicable to real fabrication.
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Abbreviations
- D :
-
bending stiffness of the top pad
- E :
-
Young’s modulus of the top pad
- h :
-
thickness of the top pad
- ν :
-
Poisson’s ratio of the top pad
- k :
-
spring constant of the sub pad
- c :
-
slope of the compressibility(percent/pressure)
- t :
-
thickness of the sub pad
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Park, Y., Jeong, H., Choi, S. et al. Planarization of wafer edge profile in chemical mechanical polishing. Int. J. Precis. Eng. Manuf. 14, 11–15 (2013). https://doi.org/10.1007/s12541-013-0002-5
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DOI: https://doi.org/10.1007/s12541-013-0002-5