Mobility change of MOSFETs in a chip-stacked multichip package
Mobility change of MOSFETs in a chip-stacked multichip package
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DOI：
10.1002/ecjb.20246
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发表时间：
2006-01-01
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影响因子：
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通讯作者：
Kuroki, Yukinori
中科院分区：
文献类型：
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作者：
Ikeda, Akihiro;Hamaguchi, Kiyoshi;Kuroki, Yukinori
我们研究了MOSFET在芯片堆叠多芯片封装中迁移率的变化。将背面研磨至50 μ m厚度的6英寸晶片切成芯片，并且用非导电膏（NCP）将芯片粘合到玻璃环氧树脂基板上，此外，以倒装芯片布置将第二芯片接合在第一芯片上。芯片间的连接是通过热压接合形成在上下芯片上的Au/Ni凸块来实现的。在堆叠第二芯片之前，第一芯片上的MOSFET没有显示出迁移率的变化，但是在堆叠芯片之后，pMOSFET的迁移率增加，nMOSFET的迁移率降低。在芯片堆叠之前，第一个芯片是稍微凸起的，但是在堆叠之后，它变形为大大凹陷的形状。可以认为，玻璃环氧树脂基板或NCP在芯片的热压键合期间经历了塑性变形，并且在热压键合过程之后，来自该变形的应变仍然存在。结果，在第一芯片中在[（1）条10上]方向上产生弯曲压缩应力，并且认为MOSFET的迁移率由于压阻效应而改变。(c)2006 Wiley Periodicals，Inc. Electron Comm Jpn Pt 2，89（7）：1-8，2006;在线发表于Wiley InterScience（www.interscience.wiley.com）。
We studied the mobility change of MOSFETs in a chip-stacked multichip package. A 6-inch wafer that had the back ground to 50 gm thickness was diced into chips and a chip was cemented to a glass epoxy substrate with a nonconductive paste (NCP), and in addition, a second chip was bonded on the first chip in a flip chip arrangement. The interchip connection was made by thermocompression bonding of Au/Ni bumps formed on the upper and lower chips. The MOSFETs on the first chip had not shown changes in mobility before stacking the second chip, but after stacking the chip, the mobility of the pMOSFETs increased and the mobility of the nMOSFETs decreased. Before chip stacking, the first chip had been slightly convex, but after stacking it was deformed to a greatly concave shape. It is considered that the glass epoxy substrate or the NCP had undergone a plastic deformation during the thermocompression bonding of the chip and that the strain from this deformation remained after the thermocompression bonding process. As a consequence, bending compressive stress occurred in the first chip in the [(1) over bar 10] direction, and it is considered that the mobility of the MOSFET changed due to the piezoresistive effect. (c) 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 89(7): 1-8, 2006; Published online in Wiley InterScience (www.interscience.wiley.com).