双极型晶体管用常压埋层硅外延的图形完整性研究

Study on Graphical Integrity of Atmospheric Buried Silicon Epitaxy for Bipolar Transistors

阐述埋层硅外延片作为当今双极型晶体管的关键战略材料,应用价值显著。但是相比常规无图案的抛光片外延,埋层硅外延制备工艺受制于外延均匀性、表面质量等参数制约,难度显著增加。基于<111>晶向的埋层硅外延将与<110>定位面垂直的方向发生图形漂移,而且反应副产物HCl会腐蚀硅片表面,图形台阶处因为取向不同,使各方向腐蚀速率不同产生图形畸变,导致光刻工艺下的对位标记无法进行。本文解释了外延生长过程中图形漂移和畸变原理,验证了生长温度、反应速率对图形漂移和畸变的影响,通过优化外延工艺参数,严格控制生产工艺,可以满足埋设层外延工艺的特殊要求,最终成功在常压状态下控制了图形漂移和畸变。

This paper describes that buried silicon epitaxial wafers, as the key substrate material of today’s bipolar integrated circuits, have very great application value. However, compared with the conventional unpatterned polished wafer epitaxy, the preparation process of buried silicon epitaxial is subject to parameters such as epitaxial uniformity and surface quality, and the difficulty is significantly increased. Based on the <111> crystal orientation will cause pattern drift in the direction perpendicular to the <110> positioning plane, and the reaction byproduct HCl will corrode the silicon wafer surface. Because of the different orientations, the different corrosion rates in each direction will cause problems such as pattern distortion, which will lead to the situation that the processed layer after the epitaxy cannot be accurately aligned with the mark left before the epitaxy. Through the analysis of the structure of Si crystals, this paper explains the principle of pattern drift and distortion that affect the quality of the epitaxial pattern integrity during the atmospheric pressure epitaxial growth process, and verifies the influence of growth temperature and reaction rate on pattern drift and pattern distortion. By optimizing the epitaxial process parameters and strictly controlling the production process, it can meet the special requirements of the buried layer epitaxial process, that succeeded in controlling the drift and distortion of graphics under normal pressure.