P型鍺與N型矽晶圓接合介面型態與電性研究

Abstract

近十幾年來，利用晶圓接合形成矽/鍺異質結構的技術漸漸在電子、光學元件與微機電上述到矚目，舉凡在太陽能、光感測器、發光二極體和射頻微機電等，文獻中都已經成功地做出不錯的特性。一般所使用的異質磊晶需要特殊的製程及設備，且兩種材料本質上4.2%的晶格常數差異使得整合上有不小的難度。 實驗中成功的利用薄晶圓以及網格狀結構兩種減少熱應力的方式將P型鍺與N型矽在氮氣及氫氣中接合在一起。以穿透式電子顯微鏡觀察，介面有一層非晶質區域會隨著退火溫度的上升減低厚度，同時有些許的聚集現象，但是卻因為晶向偏離而無法形成完美接合。電性分析顯示，介面非晶質層中擁有許多的缺陷，當厚度下降，漏電流急遽上升，如果使用氫氣氛退火則可以減緩漏電的增加。

Over the past ten years, Si/Ge heterojunction made by direct wafer bonding technology is getting more attention in electronic, optical and micro mechanical industries. Improvements in device characteristics are found in photovoltaic, photodetector, LED and RF MEMS in many research papers. Epitaxy is a special practice and costly to maintain the equipment. Also, 4.2% differences in lattice constant of Si and Ge is always an obstacle for integration. In this study, successful p-Ge/n-Si heterojunction was formed by using thinner wafer and mesa structure after annealed in nitrogen and hydrogen atmosphere. An amorphous layer between wafer pair was observed under TEM which decreased in thickness and segregated with higher annealing temperature but could not form perfect bonding due to wafer misorientation. I-V measurements showed that lots of defects exist in the amorphous layer. Leakage current increased with annealing temperature and hydrogen anneal could alleviate the phenomenon.