IWLPC (Wafer-Level Packaging) Conference Proceedings


Authors: Lucy Chen, David Chen, and Jackie Chen
Company: SEZ Taiwan
Date Published: 10/10/2004   Conference: IWLPC (Wafer-Level Packaging)

Abstract: With the increasing penetration of flip chip technology into the 300mm Wafer-Level Packaging (WLP) market, requirements for process performance of solder bump technology have become more stringent. One of the biggest challenges for 300mm WLP processing is the control of undercut and uniformity during etching of Under-Bump Metal (UBM). The performance is strongly dependent on the chemical dispense technique used to etch the wafers. Conventional processes for UBM etching use batch processing, typically wet bench systems.

These conventional approaches are subject to issues of non-uniformity that are related to poor control of chemical distribution across the wafer surface and between parallel wafer surfaces. In this paper we present the results of UBM etching using a single wafer spin processor that can provide a solution for stringent undercut control of less than 3 µm while maintaining a throughput comparable to conventional batch (wet bench) system. We have successfully demonstrated UBM etch processes for Ti/NiV/Cu, TiW/Cu, Ti/Cu based bumps with improved etching performance and uniformity.

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