以離子植入矽化鎳或鎳金屬技術製作矽化鎳接觸淺接面二極體之研究

Abstract

本論文主要探討以離子植入矽化鎳(NiSi)或矽金屬(Ni)的技術來製作NiSi/p+n以及NiSi/n+p淺接面二極體。厚度700Å的矽化鎳薄膜在經過BF2+或As+離子佈植後，熱穩定性可達到750℃，其片電阻值約在2Ω/□。在BF2+離子以80keV能量及5×1015 cm-2劑量植入NiSi/n-Si，並在爐管中作700℃的退火處理30分鐘所得到的NiSi/p+n接面二極體，漏電流密度約為 1nA/cm2，正向理想參數(forward ideality factor)為1.00，接面深度約為0.2微米。此接面二極體之漏電流的活化能約為1.13eV，顯示其漏電主要是藉由擴散電流(diffusion current)所導致。另外，對漏電流成份的分析結果顯示此接面二極體的漏電主要來自二極體的周邊，而非底部。 在As+離子以80keV能量及5×1015 cm-2劑量植入NiSi/p-Si，並在爐管中作750℃的退火處理30分鐘所得到的NiSi/n+p接面二極體，其漏電流密度約為8 nA/cm2，正向理想參數(forward ideality factor)為1.17，接面深度約為0.13微米。此接面二極體之漏電流的活化能在低溫時(40~100℃)約為0.7eV，顯示其漏電流主要是藉由產生電流(generation current)所導致；在高溫時(120~180℃)，活化能約為0.9eV，顯示漏電流是由擴散電流(diffusion current)與產生電流(generation current)各佔一部份。另外，對漏電流成份的分析結果也顯示此接面二極體的漏電主要也是來自二極體的周邊，而非底部。

This thesis studies the formation and characterization of NiSi/p+n and NiSi/n+p shallow junctions involving the technique of implant into/through silicide (ITS) or metal (ITM). It is found that the BF2+- or As+-implanted NiSi films of 700Å thickness were thermally stable at temperatures up to 750℃. The electrical characteristics of the NiSi/p+n shallow junction diodes fabricated by ITS scheme are superior to those of the diodes fabricated by ITM scheme, presumably due to more serious knock-on effect of Ni atoms in the ITM scheme. For the p+n junction diodes fabricated using the ITS scheme, BF2+ implantation at 80keV to a dose of 5×1015 cm-2 followed by a furnace annealing at 700℃ for 30 min resulted in NiSi/p+n shallow junctions with a junction depth of about 0.2μm and a reverse leakage current density of about 1 nA/cm2 and a forward ideality factor of nearly unity. The reverse bias leakage current of this NiSi contacted p+n shallow junction is determined to be dominated by diffusion current and is mainly contributed by the peripheral leakage. For the n+p shallow junction diodes fabricated using the ITS scheme, As+ implantation at 80 keV to a dose of 5×1015 cm-2 followed by a furnace annealing at 750℃ for 30 min resulted in NiSi/n+p shallow junctions with a junction depth of about 0.13μm and a reverse leakage current density of about 8 nA/cm2 and a forward ideality factor of 1.17. It is found that leakage current of this NiSi contacted n+p shallow junction is dominated by generation current at lower temperatures (40~100℃) and is mainly contributed by the peripheral leakage.