Nondestructive Laser Debonding of Designable Responsive and Buffer Layers for Wafer Level Packaging

The advancements in the semiconductor industry driven by IoT, automotive advancements, communications and virtual requirements require the development of advanced wafer-level packaging (WLP) processes for ultra-thin device and system integration. The trend towards extreme thinning of device wafers in WLP processes is driving the need for temporary carrier technology. With the advantages of large area, non-contact, high efficiency and controllability, laser debonding technology has become an emerging key technology in the semiconductor industry. Because the redistribution layer is immediately on top of the debonding layer, minimizing the forces during debonding is critical to maintaining the integrity of ultrathin wafers. However, slight device damage and degradation of device characteristics during laser debonding remain unsolved due to the laser-induced transient high temperature and shock wave effects. Herein, we demonstrate a novel non-destructive laser debonding process for advanced WLP by rationally designing responsive layers, buffer layers, and bonding layers. The research results show that the decomposition of a-Si:H in the response layer can be selectively induced by UV laser to generate molten polysilicon and release H
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rapidly. The resulting shock wave effect rapidly expands the exfoliation layer, effectively separating the device wafer from the glass carrier. During laser debonding, the buffer layer compensates for internal stress, thermal damage, and optical damage, protecting the ultra-thin device wafer from any structural damage (such as cracks, chips, or stick marks) caused by transient high temperatures and shock waves. By precisely controlling the input of laser energy and designing appropriate response layers and buffer layers, ultra-thin device wafers can be protected from any structural damage, making them highly possible in the field of advanced integrated circuit and conformal chip array manufacturing. We believe that these encouraging results motivate us to make a leap forward in the field of advanced flexible electronic packaging.