Ablation Behaviour of Photosensitive Materials in Laser Debonding Processes for Advanced Packaging

The rapid development of high-end communications, artificial intelligence, internet of things and wearable devices has greatly facilitated the application of advanced packaging technology in the high-end chip industry to achieve miniaturisation, high density, multi-functionality, low power consumption and low cost of high-end chips. Faced with the continuous development of device wafers in the direction of large size, thinner and three-dimensional stacking, the field of advanced packaging has proposed temporary bonding and debonding (TBDB) processes to reduce the breakage rate of ultra-thin wafers. Among them, laser debonding has become the mainstream solution in the TBDB processes due to its unique advantages in terms of controllable energy, application flexibility and programmable processing. However, little has been reported about the ablation behaviour of polymer-based photosensitive materials during laser debonding. Here, we systematically analyzed the ablation behavior of a polymer-based photosensitive material in surface ablation and bulk ablation modes. In the surface ablation mode, as the laser energy density increases, the photosensitive material layer first undergoes an swell stage in the laser-irradiated region, followed by an ablation removal stage. Compared with the surface ablation, the bulk ablation mode results in a more intense stronger high-temperature and high-pressure environment due to confined-domain, thereby creating grooves in the ablation region of the photosensitive material layer. This work provides the theoretical and experimental basis for the development of new laser debonding processes required for advanced packaging of high-end chips.