Impact of Thermomechanical Stresses on Bumpless Chip in Stacked Wafer Structure
Impact of Thermomechanical Stresses on Bumpless Chip in Stacked Wafer Structure
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DOI：
10.7567/jjap.52.05fe01
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发表时间：
2013-05
影响因子：
1.5
通讯作者：
Y. Mizushima;H. Kitada;C. Uchibori;N. Maeda;S. Kodama;Young-Seob Kim;K. Fujimoto;S. Yoshimi;Tomoji Nakamura;T. Ohba
中科院分区：
文献类型：
--
作者：
Y. Mizushima;H. Kitada;C. Uchibori;N. Maeda;S. Kodama;Young-Seob Kim;K. Fujimoto;S. Yoshimi;Tomoji Nakamura;T. Ohba
研究了厚于20 μm的介质聚合物和高模量介质聚合物在无凸点晶片上芯片（COW）工艺中产生的热机械应力引起的裂纹形成。根据应力模拟，热应力随聚合物厚度增加，其中苯并环丁烯（BCB）基树脂的应力值在100至200 MPa范围内。在使用环氧基树脂和BCB基树脂的混合结构中的热应力被计算为小于100 MPa。因此，发现聚合物以及Si芯片的厚度的减小在避免COW结构中的裂纹形成方面是有效的。此外，为了研究裂纹驱动力，计算了能量释放率（ERR）。裂纹向硅片角部扩展，与实验结果一致。在COW结构上，薄Si芯片和低模量聚合物扩展了工艺窗口。
Crack formation due to thermomechanical stresses generated by a dielectric polymer thicker than 20 µm and by that with high modulus during the bumpless chip-on-wafer (COW) process has been investigated. According to the stress simulation, thermal stresses increase with polymer thickness where the stress value ranges from 100 to 200 MPa for benzocyclobutene (BCB)-based resin. Thermal stresses in the hybrid structure using epoxy-based resin and BCB-based resin were calculated to be less than 100 MPa. Thus, the reduction of the thicknesses of the polymer as well as the Si chip was found to be effective in avoiding crack formation in the COW structure. Moreover, to investigate the crack driving force, the energy release rate (ERR) was calculated. The crack propagates toward the Si chip corner and the result is consistent with the experiment. On the COW structure, a thin Si chip and a low-modulus polymer expand the process window.