IR Laser Release for 3D Stacked Devices: Effect of the Release Stack Structure on the Debonding Mechanism

Abstract

To achieve a reliable debonding and to include the infrared laser release process into a full integration flow, optimizations of the IR release process and subsequent cleaning are presented. In this paper several structural parameters of the laser release stack are explored with optical simulation and correlated to experimental results. This allows us to show the important affecting parameters, to develop a structure of reference and to open paths towards a leaner and more efficient process. It is also shown that the debonding mechanism is based on cracks propagation and not purely based on ablation. Finally, further demonstration of the process is achieved by showing the cleaning of laser residues and a full 300 mm wafer processing on temporary carrier, including backside thinning and subsequent transfer and release to a target wafer.