Wafer-bonded 2-D CMUT arrays incorporating through-wafer trench-isolated interconnects with a supporting frame.
Wafer-bonded 2-D CMUT arrays incorporating through-wafer trench-isolated interconnects with a supporting frame.
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晶圆键合 2-D CMUT 阵列将贯穿晶圆的沟槽隔离互连与支撑框架结合在一起。
DOI：
10.1109/tuffc.2009.1018
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Khuri-Yakub,ButrusT
中科院分区：
文献类型：
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作者：
Zhuang,Xuefeng;Wygant,IraO;Lin,Der-Song;Kupnik,Mario;Oralkan,Omer;Khuri-Yakub,ButrusT
本文报道了晶片键合，完全填充的2-D电容式微机械超声换能器（CMUT）阵列。迄今为止，没有成功的晶片通孔制造技术已被证明是与制造CMUT阵列的晶片键合方法兼容。作为晶片通孔的替代方案，具有支撑框架的沟槽隔离被结合到2-D阵列中以提供晶片通电连接。CMUT阵列构建在绝缘体上硅（SOI）晶片上，并且到阵列元件的所有电连接都通过高导电性硅衬底被带到晶片的背面。相邻的阵列元件由器件层和体硅上的沟槽分开。提供机械支撑的网状框架结构嵌入在硅柱之间，硅柱与各个元件电连接。我们成功地制作了一个16倍16单元的2-D CMUT阵列使用晶圆键合与成品率为100%。在整个阵列中，脉冲回波幅度分布是均匀的（sigma =平均幅度的6.6%）。在一种设计中，我们测量了7.6 MHz的中心频率，换能器表面的峰峰值输出压力为2.9 MPa，3 dB部分带宽为95%。通过将制造的2-D阵列之一芯片到芯片键合到定制设计的集成电路（IC）来演示体积超声成像。这项研究表明，通过晶圆沟槽隔离与支撑框架是一个可行的解决方案，提供电气互连CMUT元件和2-D阵列制造使用晶圆键合提供良好的性能。
This paper reports on wafer-bonded, fully populated 2-D capacitive micromachined ultrasonic transducer (CMUT) arrays. To date, no successful through-wafer via fabrication technique has been demonstrated that is compatible with the wafer-bonding method of making CMUT arrays. As an alternative to through-wafer vias, trench isolation with a supporting frame is incorporated into the 2-D arrays to provide through-wafer electrical connections. The CMUT arrays are built on a silicon-on-insulator (SOI) wafer, and all electrical connections to the array elements are brought to the back side of the wafer through the highly conductive silicon substrate. Neighboring array elements are separated by trenches on both the device layer and the bulk silicon. A mesh frame structure, providing mechanical support, is embedded between silicon pillars, which electrically connect to individual elements. We successfully fabricated a 16 times 16-element 2-D CMUT array using wafer bonding with a yield of 100%. Across the array, the pulse-echo amplitude distribution is uniform (sigma = 6.6% of the mean amplitude). In one design, we measured a center frequency of 7.6 MHz, a peak-to-peak output pressure of 2.9 MPa at the transducer surface, and a 3-dB fractional bandwidth of 95%. Volumetric ultrasound imaging was demonstrated by chip-to-chip bonding one of the fabricated 2-D arrays to a custom-designed integrated circuit (IC). This study shows that through-wafer trench-isolation with a supporting frame is a viable solution for providing electrical interconnects to CMUT elements and that 2-D arrays fabricated using wafer-bonding deliver good performance.