Precise modulation of the debonding behaviours of ultra-thin wafers by laser-induced hot stamping effect and thermoelastic stress wave for advanced packaging of chips

Abstract

Laser debonding technology has been widely used in advanced chip packaging, such as fan-out integration, 2.5D/3D ICs, and MEMS devices. Typically, laser debonding of bonded pairs (R/R separation) is typically achieved by completely removing the material from the ablation region within the release material layer at high energy densities. However, this R/R separation method often results in a significant amount of release material and carbonized debris remaining on the surface of the device wafer, severely reducing product yields and cleaning efficiency for ultra-thin device wafers. Here, we proposed an interfacial separation strategy based on laser-induced hot stamping effect and thermoelastic stress wave, which enables stress-free separation of wafer bonding pairs at the interface of the release layer and the adhesive layer (R/A separation). By comprehensively analyzing the micro-morphology and material composition of the release material, we elucidated the laser debonding behavior of bonded pairs under different separation modes. Additionally, we calculated the ablation threshold of the release material in the case of wafer bonding and established the processing window for different separation methods. This work offers a fresh perspective on the development and application of laser debonding technology. The proposed R/A interface separation method is versatile, controllable, and highly reliable, and does not leave release materials and carbonized debris on device wafers, demonstrating strong industrial adaptability, which greatly facilitates the application and development of advanced packaging for ultra-thin chips.

Keywords

• laser debonding behaviours
• laser-induced hot stamping effect
• thermoelastic stress wave
• advanced packaging