Single Wafer Resist Removal For Wafer-Level Packaging With Improved Process Integration
Authors: Richard Peters, Travis Acra, Yuanmei Cao, Kimberly Pollard, Don Pfettscher, Meng Guo Company: Dynaloy, a Subsidiary of Eastman Chemical Co. Date Published: 11/5/2013
IWLPC (Wafer-Level Packaging)
Abstract: Removal of thick resists while balancing compatibility with materials including metals, solder, and dielectrics is an underappreciated challenge in wafer level packaging (WLP). Complicating the challenge are process integration issues including the effects of upstream processes such as lithography, resist curing, and electroplating, downstream processes such as surface conditioning, field metal etching, and reflow, and finally health and safety (HSE) issues related to the cleaning chemistry and process. We have developed an advanced single wafer cleaning technology that meets the needs of the WLP industry for thick resist removal while also resulting in improved process integration. The platform, called CoatsCleanTM, is a combination of both process and chemical technology. In this paper, we will show that the unique process can enable the use of safer chemistries for WLP, specifically TMAHfree chemistries, that also result in improved downstream process integration. In addition to resist removal, the process and chemistry combination will be shown to exhibit exceptional compatibility with solder and metals resulting in better surface conditions. These advantages culminate into an ability to eliminate some downstream processing steps and ultimately result in improved and HSE-friendly process integration. Results will be compared to a typical immersion process highlighting the enabling capability of the technology. The technology will be shown to be ready for manufacturing with whole wafer cleaning results.