Self-Alignment with Copper Pillars Micro-Bumps for Positioning Optical Devices at Submicronic Accuracy
Self-Alignment with Copper Pillars Micro-Bumps for Positioning Optical Devices at Submicronic Accuracy
复制标题
利用铜柱微凸块进行自对准，以亚微米精度定位光学器件
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
P. Arguel
中科院分区：
文献类型：
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作者：
Yézouma D. Zonou;S. Bernabé;D. Fowler;M. Francou;O. Castany;P. Arguel
本文研究了铜柱微凸块叠置芯片的自对准特性。芯片的特征对准标记用于测量装配后产生的偏移量。根据工艺的不同，在x和y方向上的校准精度优于0.5µm。该芯片还具有在前端线（FEOL）制造的波导和垂直光栅耦合器（VGC），并组织以实现芯片之间的光学互连。测量了芯片之间的光耦合，并与数值模拟进行了比较。在研究了助焊剂和无助焊剂处理对焊盘润湿和装配成品率的影响后，获得了这种高精度的自对准。利用飞行时间二次离子质谱（ToF-SIMS）分析了凹凸表面的成分，以了解每种处理的影响。本研究证实，铜柱微凸点可用于光子集成电路（PIC）与另一个芯片（例如微透镜阵列）的自对准，以实现光纤到PIC的高通量对准。
This paper studies the self-alignment properties between two chips that are stacked on top of each other with copper pillars micro-bumps. The chips feature alignment marks used for measuring the resulting offset after assembly. The accuracy of the alignment is found to be better than 0.5 µm in × and y directions, depending on the process. The chips also feature waveguides and vertical grating couplers (VGC) fabricated in the front-end-of-line (FEOL) and organized in order to realize an optical interconnection between the chips. The coupling of light between the chips is measured and compared to numerical simulation. This high accuracy self-alignment was obtained after studying the impact of flux and fluxless treatments on the wetting of the pads and the successful assembly yield. The composition of the bump surface was analyzed with Time-of-Flight Secondary Ions Mass Spectroscopy (ToF-SIMS) in order to understand the impact of each treatment. This study confirms that copper pillars micro-bumps can be used to self-align photonic integrated circuits (PIC) with another die (for example a microlens array) in order to achieve high throughput alignment of optical fiber to the PIC.