Advanced wafer bonding and laser debonding

Abstract

This paper describes the development of a wafer debonding process and tooling based on 355 nm UV laser ablation. While laser-assisted debonding of polyimide-based materials at shorter UV wavelengths has been described previously, this work describes a method having two major advantages over earlier methods: 1) a significantly more compact and affordable diode-pumped solid state 355 nm laser source is combined with a high-speed optical scanner to create a rapid debonding module with a small footprint, and 2) the addition of a very thin UV ablation layer to the glass handler ensures that release will occur, independently of the adhesive used to bond the wafer. The first enhancement is designed to enable high-throughput debonding at lower cost than earlier laser tools, while the second enhancement is designed to greatly expand the adhesive choices available to device manufacturers. Flexibility in material choice for both the release layer and the adhesive layer permits the manufacturer to meet post-wafer thinning process and temperature compatibility needs. In this research paper, the many benefits of this novel room-temperature debonding technology are reported along with examples of successfully demonstrated adhesives and release layers.