Chen Chuantong, Suganuma Katsuaki
Laboratory of flexible and power three dimensional system integration, Osaka university, Ibaraki-shi, Osaka, 567-0047, Japan.
The institute of scientific and industrial research, Osaka university, Ibaraki-shi, Osaka, 567-0047, Japan.
Sci Rep. 2020 Jun 3;10(1):9042. doi: 10.1038/s41598-020-66069-8.
This paper introduced an approach of die-attach bonding technology based on a low-cost high-purity aluminum (99.99%) sheet in a silicon carbide (SiC)/direct bonded aluminum (DBA) power module. Both sides of an Al sheet were sputtered by a thin Ti and Ag layer, which generated a tensile stress of 166 MPa on the Al surface. After heating, the Al surface displayed a large quantity of Ag hillocks by stress self-release due to the coefficient of thermal expansion (CTE) mismatch among Al, Ti, and Ag. The SiC/Al sheet/DBA substrate interfaces were bridged by the generation of these hillocks, which correspond to a robust shear strength of 33.4 MPa in a low-temperature process. Hillocks generation and the interface bonding mechanism by surface stress self-generation and self-release were systematically analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The shear strength remains constant at 32.1 MPa after high-temperature storage at 250 °C for 500 h, which suggests that the Al sheet possesses excellent high-heat resistance and thermal stability. This novel approach of die-attach bonding technology serves as an attractive alternative for SiC power devices that require high-temperature performance.
本文介绍了一种基于低成本高纯度铝（99.99%）片材的芯片键合技术，应用于碳化硅（SiC）/直接键合铝（DBA）功率模块。在铝片的两面溅射一层薄的钛和银层，这在铝表面产生了166兆帕的拉应力。加热后，由于铝、钛和银之间的热膨胀系数（CTE）不匹配，铝表面通过应力自释放出现大量银小丘。这些小丘的产生使SiC/铝片/DBA衬底界面连接起来，在低温工艺中对应的剪切强度高达33.4兆帕。通过扫描电子显微镜（SEM）、X射线衍射（XRD）和透射电子显微镜（TEM）系统地分析了小丘的产生以及表面应力自生自释的界面键合机制情况。在250℃高温储存500小时后，剪切强度保持在32.1兆帕不变，这表明铝片具有优异的耐高温性和热稳定性。这种新颖的芯片键合技术方法为需要高温性能的SiC功率器件提供了一个有吸引力的替代方案。
