Efficient Probing Schemes for Fine-Pitch Pads of InFO Wafer-Level Chip-Scale Package

• Main Authors: Huang Yu Chieh, 黃裕傑
• Other Authors: Wu, Cheng Wen
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/64107426437393956996

碩士 === 國立清華大學 === 電機工程學系 === 104 === With the increasing demand of super high scale of integration and small form factor in advanced semiconductor products, especially those that integrate DRAM and logic dies, 3D IC and Wafer-Level Chip-Scale Packaging (WLCSP) are considered promising approaches. In Integrated Fan-Out (InFO) WLCSP, a large number of fine-pitch pads, where neighboring pads cannot be probed simultaneously due to insufficient pitch, are used as the contact interfaces of inter-die interconnections. If the fine-pitch pads cannot be probed, the interconnections between the pads and boundary scan cells (BSCs) cannot be tested, which can lead to higher defect level. From industrial investigation, untested fine-pitch pads lead to 1-2% test coverage loss. To improve the overall test coverage, we propose a pre-bond probing methodology for fine-pitch pads of InFO WLCSP. By the proposed probing schemes, open/short faults on the interconnects between the fine-pitch pads and BSCs can be all tested by the ATE. Moreover, for short faults that only occur between adjacent pads (interconnects), we propose a grouping method to determine the test patterns at each probing stage, which can minimize the test time. We also show that our method can achieve 100% test coverage of open/short faults.