鍺離子佈植對矽化鈦淺接面效應之研究

Abstract

本論文研究鍺離子佈植對矽化鈦淺接面產生之效應,利用不同的方 法製 做淺接面.(1)用鍺離子佈植預先非晶化的複晶矽或非晶矽當擴散源 ,由於 複晶矽中大部份的擴散管道被鍺離子破壞,經鍺離子預先非晶化的二極體 有較淺的接面, 在不加入鈦的情況下,用此方法可得到一個接面深度小 於60nm的二極體,但是度上鈦以後,經矽化鈦轉化過程,接面深度會加到100 nm.另一組二極體是用傳統的方法,將硼離子植入經鍺離子非晶化的矽基 板,接面深度也是有效減少,而由鍺離子佈植產生的缺陷,可由矽化鈦轉化 過程有效消除. (2)將硼離子佈植入經鍺離子預先佈植的矽化鈦以形成接 面,利用矽化鈦含非晶矽或複晶矽當緩衝層的結構及傳統的離子佈植穿過 矽化鈦等方法製做二極體,有加入鍺離子佈植的二極體,在電性上有很大的 改善,加入鍺離子的矽化鈦含非晶矽當緩衝層的二極體,經 850C退火15分 鐘後,可得到一個超淺接面,接面深度小於50nm以及低於0.3nA/ cm2 的漏 電流. The effects of Ge implantation on the Ti-silicide shallow junction have been studied. Different kind of diode structure were fabricated to form shallow junction. First, the shallow junctions were performed by out diffusion of boron from Ge preamorphized poly-Si or a-Si. It was observed that the junction depth of the samples with Ge-preamorphization would significantly reduced. In the absence of Ti silicidation, an ultra-shallow junction with junction depth < 60nm can be obtained. But, after the sample was covered with Ti, the silicidation would enhance the boron diffusion. Another set of samples were also fabricated by implanting boron into Ge preamorphized silicon substrate. The junction depth is also reduced by Ge-preamorphization. An additional benefit of the silicidation for this set of samples is to efffectively annihilate the Ge-implanted defects. Second, the shallow junction were formed by implanting through silicide with a-Si or poly-Si as buffer layer and the conventional method, implanting through silicide. The electrical characteristics of these junctions can be greatly improve by Ge implantation. The Ge-implantation would also enhance boron diffusion.