Development of three-dimensional wafer level chip scale packaging using via last TSV and UV laser releasable temporary bonding technologies

• Published in: Microsystem technologies : sensors, actuators, systems integration Vol. 27; no. 11; pp. 4121 - 4125
• Main Authors: Wang, Chengqian, Zhang, Meng, Ming, Xuefei, Ma, Shuying, Yu, Daquan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2021
• Subjects: Electronics and Microelectronics; Engineering; Instrumentation; Mechanical Engineering; Nanotechnology
• ISSN: 0946-7076; 1432-1858
• DOI: 10.1007/s00542-021-05228-x

3D WLCSP with via last TSV and UV laser releasable temporary bonding technologies is an ideal scheme to meet the increasing high performance, low cost and small-form-factor requirements. In present paper, we demonstrate a thin 3D WLCSP process using 8 inch wafers, and a number of critical process technologies were developed to realize the final 3D assembly. For example, higher deposition temperature PECVD with single frequency was applied for the passivation layer growth owing to the good quality temporary bonding film with high temperature and chemical resistance properties. A new suspension litho coating method was successfully developed to complete redistribution layer and bump formation.Automated optical inspection (AOI) results show a good bump height and coplanarity with the yield of 99.1%. In favor of 355 nm UV laser, the carrier glass was easily debonded and the device wafer was completely cleaned. Finally, chip to chip stacking process was carried out to accomplish the final 3D stacking package.