以氮離子佈植技術進行選擇性成長矽磊晶層

Abstract

對於以二氯矽烷與氫氣混合為原料的選擇性矽磊晶成長,我們研究其在 850'C 到 1000'C 低壓下的化學氣相沉積於(100),(110)和(111)的基底 上. 磊晶層的表面結構高度受於沉積溫度與基底方向的影響. 藉著正確清 洗步驟,長於 850'C (100)基底上的高品質矽晶層能被獲得. 然在(110) 或(111)基底上,我們無法獲得明亮的矽晶表面,除非沉積溫度提昇 至1000' C. 雖然高溫的矽晶成長能導至好的磊晶層,但我們也獲得切面結 構與下切效應所引起的粗裂邊緣.使用氮離子佈植取代傳統以二氧化矽當 絕緣體的新絕緣技術已被發展出來. 藉著正確的氮離子量和溫度效應,似 氮矽化合物的介電質層能獲得.這層似氮矽化合物的品質強烈受致於離子 佈植量和磊晶溫度的影響. 對於這方面研究,我們發現在高量的氮離子佈 植和低溫磊晶所形成似氮矽化合物的介電質層,它能導至矽晶成長有一個 好的選擇性. 高溫的矽晶成長步驟能破壞氮矽間的鍵結與增強氮原子的向 外擴散,導至選擇性效果變差.此外,在正確的條件下,於未離子佈植的區域 高品質矽磊晶可獲得,且沒有單晶 矽或多晶矽凝結於離子佈植區域. Selective epitaxial growth (SEG) of silicon using a dichloro- silane-hydrogen mixture in a low pressure chemical vapor deposition (LPCVD) hot-wall reactor is studied. Si epitaxy is carried out on (100),(110),and(111) Si substrates in the temperature range of 850'C to 1000'C. The surface morphology of epilayers is highly influenced by the deposition temperature and the substrate orientation. With proper wafer preparation, high quality Si epilayers on (100) substrates are obtained at 850'C. However, specular surface of epilayers on (110) or (111) substrates can not be achieved unless the deposition is raised to 1000'C. Although the high temperature deposition can lead to good epilayers, rough edges due to the facet formation and the undercutting effect are also obtained. A new isolation technology using N+ ion implantation is developed to replace the conventional SiO2 isolation. A nitride- like dielectric layer can be obtained with proper N+ ion dose and thermal treatment. The quality of this nitride-like layer is strongly affected by the ion dose and the deposition temperature . In this study, it is found that high dose of N+ ion implantation and low deposition temperature can form a nitride- like dielectric surface layer which leads to a good selectivity during the Si epitaxy. A high deposition temperature step can break the Si-N bond and enhance the outdiffusion of nitrogen atoms, then the selectivity is degraded. With proper condition, high quality Si epilayers are obtained on un-implanted regions and there is no Si or poly-Si nuclei on N+ ion implanted regions.