具矽穿孔原子晶片之開發與製作應用於超高真空原子光學元件

The development and fabrication of atom chips with through silicon via for ultra-high-vacuum atom optics cell

李相甫(Hsiang-Fu Li)

指導教授 ： 莊賀喬

國立臺北科技大學/機電學院/機電整合研究所/碩士(2012年)

摘要

如何將玻色-愛因斯坦冷凝聚(Bose-Einstein Condensation, BEC)系統微小化已成為目前重要的課題之一，本文在這樣的前提下引入目前最熱門的矽穿孔 (Through Silicon Via, TSV)技術來製作具饋通孔的原子晶片，再將製做完成後的晶片與Pyrex玻璃管做陽極接合封裝，並使原子晶片與玻璃管能夠在超高真空環境(10-10 Torr)下透過TSV通高電流至內部的導線上且能同時維持超高真空 (Ultra-High-Vacuum, UHV)，因此如何提高晶片中TSV的導電及真空良率為本研究的最主要目標。使用由下而上 (Bottom-up)的電鍍方式填孔後，再利用微製程技術在晶片的正、反面鍍金屬薄膜、微影、蝕刻，最後使用陽極接合技術將矽基板的晶片與Pyrex方管做接合，陽極接合製程需要高溫 (350˚C)及高電壓 (1000V)，在高溫的條件下，TSV內的電鍍銅柱及矽晶片的熱膨脹量相差甚大，因此如何在陽極接合後使電鍍填孔的銅柱不與矽基板分離且可以抵擋超高真空即是本研究的重點。在晶片使用上TSV也要能夠承受高電流，避免通高電流時TSV先燒斷形成斷路，在本研究中製作了三種不同直徑的TSV，包含100μm、70μm、50μm，而這三種中任一個TSV皆能在真空環境 (70 Torr)及一般大氣環境通17安培的電流後而不燒斷，因此輕易地通過連續5安培 (Amps)的門檻條件，而通過17安培的高電流後TSV仍然能夠通過氦氣測漏的檢測，並且在完成陽極接合後可以抽至超高真空 (8×10-10 Torr)。另外，晶片製作中凸起的TSV蘑菇頭卻會因為蒸鍍時的階梯覆蓋效應而影響製程上的良率，在經過製程改善後，TSV的導電良率能從50%增加到100%，真空洩漏良率能從75%上升至81.25%。

關鍵字

玻色-愛因斯坦冷凝聚 ； Through Silicon Via (TSV) ； 感應耦合電漿離子蝕刻(ICP-RIE) ； Bottom-up ； 陽極接合 ； Ultra-High-Vacuum

並列摘要

How to miniaturize the BEC system has become one of the important topics in the atomic physics field. In this thesis, we integrated the most popular TSV technique to make the feedthrough atom chips which will be anodically bonded to a Pyrex glass cell. Then the high current can be applied to the metal wires on the atom chip through the TSV under ultra-high vacuum environment (10-10 Torr) to produce the magnetic field without any leaks. Thus how to improve the conductive and vacuum yields of TSV on atom chips is also the important goal of this study. The feedthrough vias are filled by the bottom-up copper electroplating. The front side metal wires and back side bonding pads on atom chips can be patterned by the general lithography process. Then the atom chip will be anodically bonded to a Pyrex glass cell under the temperature of 350°C and electrical field of 1000 volts. The thermal expansion issue between the electroplated TSV and the silicon wafer under high temperature (350°C) environment is also discussed in the later section. In addition, the TSV of atom chips also has to withstand high current (at least 5 Amps) to generate the adequate magnetic field for BEC experiments. Hence, three different TSV sizes (100μm, 70μm and 50μm) have been fabricated and tested for continuously running a maximum current of 17 Amps without burnout both under vacuum(70 Torr) and in air. Thus it easily passed the threshold conditions of the 5 Amps current for BEC experiments. After high current test, the TSV of atom chips can also pass a helium leaking detection and can be pumped to the ultra-high vacuum (8×10-10 Torr) after anodic bonding process. Moreover, the fabrication yield will be affected by the electroplated TSV plug due to the step coverage effect during the evaporation process. After a process improvement, the TSV conductive and vacuum yields are raised from 50% to 100% and 75% to 81.25%, respectively.

並列關鍵字

Bose-Einstein Condensation(BEC) ； Through Silicon Via (TSV) ； Bottom-up ； ICP-RIE ； anodic bonding ； Ultra-High-Vacuum

參考文獻

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