重掺砷衬底外延工艺研究

The Investigation of the Process of Growing Epitaxial Layer on Heavy Arsenic Doping Substrate

在重掺砷(As)衬底上生长外延层一直是外延工艺难点。外延工艺过程中由于衬底的掺杂浓度与外延层的掺杂浓度相差很大,自掺杂与固态外扩散现象严重,使得外延过渡区变宽,工艺很难控制。在确保外延层晶格结构完整、表面质量完美的前提下,适当增加外延生长速率、降低外延生长温度可减小自掺杂与固态外扩散的影响。结合多晶硅背封法、二步外延法等对工艺过程进行优化,可有效抑制自掺杂现象从而提高外延片的质量。

In this paper, the difficulty of grow epitaxial layer on heavy arsenic doping substrate has been studied, The self-doping, outward difusion in solid state can influence the impurities distribution in the area close to the boundary layer of the substrate across the depth, Accelerate the speed of grow epitaxial layer, Reduced the temperature of grow epitaxial layer are used to reduce the influence of outward difusion phenomenon. Polysilicon back-seal, two-step epitaxial and several ways are used to reduce the influence of self-doping phenomenon. Finally,the epitaxial growth technique has been optimized.