離子佈植矽單晶之退火奈米雙晶組織研究

Abstract

利用離子佈植將雜質掺入矽單晶乃現今半導體業最普遍採用的方法之一，而隨著電子元件微型化的趨勢越來越明顯，薄型離子佈植矽元件退火處理後的結構分析越顯得重要。許多研究顯示經過退火之後的離子佈植矽會產生平面缺陷如疊差、雙晶及層狀雙晶，而再結晶層之微結構改變與介面的生成會帶來巨大的影響。 本實驗將研究重點置於離子佈植矽退火後的雙晶結構以及固相磊晶成長的的演變。針對離子佈植矽進行不同時間的退火處理，以場發射式之高解析度穿透式電子顯微鏡觀察其顯微組織。另外本實驗還分析不同佈植能量的離子佈植矽，觀察由能量這個變因所造成的影響。 實驗分別採用150KeV與200KeV以1×1016/㎝2劑量之Ar+佈植於p-type矽單晶後在800℃退火。經過TEM模擬分析，退火後的離子佈植矽會的確產生疊差，以及層狀之奈米級雙晶。隨著退火時間由10min增加至1hr，固相磊晶成長前緣由原先之結晶/非晶介面(分別為270nm與340nm)往試片表面前進。而從1hr之後到4hr之間停止，自4hr到8hr之間則停滯不前，維持在160nm與220nm處。不同的佈植離子濃度分佈對後續之熱處理後的結構有巨大的影響。高佈植能量於在結晶初期則有遲緩的效果由800℃/10 min此一條件可以觀察得到。

Ion implantation is the most popular method for doping the silicon wafer in recent semiconductor industry. Following the recent trend of miniaturization of microelectronic devices, microstructure analysis of thin film recrystallized, ion implanted silicon becomes more and more important. Previous research work has indicated that planar defects such as stacking faults, twins, and lamellar nano-twins will formed in ion implanted silicon thin film during annealing. It is known that twin boundaries significantly affect electrical properties of thin films. However, a fundamental knowledge of lamellar nano-twins is not yet been understood. In this work, more attention has been paid to the nano-twins and the evolution of solid phase epitaxial regrowth in the annealed specimens. Using field emission gun transmission electron microscope, we make microstructure observations upon different annealing cases, which include different annealing time and different implantation energy, to elucidate the micro structural development. Two implantation energies used on p-type silicon wafers are 150KeV and 200KeV, respectively. The dose is 1×1016 Ar+/㎝2 for both cases, and annealing temperature is 800℃. After TEM examination, it is evident that stacking faults and lamellar nano-twins did formed on {111} of ion implanted silicon during annealing. As annealing time increases from 10 min to 1 hr, the solid phase epitaxial regrowth (SPER) front moves from the previous crystalline/amorphous interface, 270 nm and 340 nm in each case, toward specimen surface. SPER front stopped at certain depths for annealing time between 1hr and 4hr, and there were no further movements for annealing time 4hr and 8hr, the SPER front stopped at depth of 160 nm and 220 nm in each case. Different ion concentration distribution along implant direction has a great impact on the subsequent annealing treatment. Higher implantation energy retards the process of recrystallization at the initial stage of annealing (i.e. 10 min @800℃); the corresponding TEM reveals that some amorphous areas still exist.