Co与掺杂Si固相反应形成CoSi2接触pn结及反应过程中As的行为研究

研究经扩散或离子注入掺B、P、As的硅表面上形成自对准CoSi_2薄膜接触和pn结技术.采用离子束溅射Co膜和Co/Si快速热处理(RTP)固相反应形成CoSi_2薄膜.在掺杂Si上形成CoSi_2薄膜以后,薄层电阻可下降一个数量级.对AS离子注入样品中,研究了不同硅片热处理工艺对As在Co/Si反应过程中再分布的影响.实验结果表明,对于CoSi_2形成之前杂质先经激活退火的硅样品,As在Co/Si固相反应过程中发生显著的“雪犁”效应,而在CoSi_2形成之前未经激活退火的样品,在杂质激活和Co/Si固相反应共退火过程中,As的行为则有明显不同.扩展电阻和电学测试表明,用这两种不同热处理工艺,在CoSi_2/Si界面处均可获得较高的载流子浓度,形成的CoSi_2接触pn结具有良好的二极管I-V特性,其反向漏电流明显小于对比实验的Al/Si接触pn结.

FORMATION OF pn JUNCTION WITH CoSi_2 CONTACT BY SOLID STATE INTERACTION OF Co WITH DOPED Si AND ASENIC BEHAVIOR DURING THE INTERACTION

This work studied the technology of formation of pn junction and self-aligned CoSi2 film contact on Si doped with B P As by diffusion or ion implantaion. Ion beam sputtering was applied for Co film deposition, and solid state interaction of Co/Si was performed by rapid thermal process (RTF) to form CoSi2 films. The sheet resistances of doped Si regions decreased by an order of magnitude after CoSi2 formation. For the samples implanted with As, the effects of different thermal processes on As redistribution during interaction of Oo/Si were investigated. Experimental results indicated that in the case of conventional process (As was activated prior to CoSi2 formation), a snowplow effect of As during interaction of Co/Si was observed. In the case of concurrent process (As activation and interaction of Co/Si were carried out in one step), As exibited an obviously different behavior. The spreading resistance probe and electrical characterization showed that, for either of the above two cases, a high .carrier concentration can be produced at the interface of CoSi2/Si, and the pn junctions with CoSi2 contact exibited good I-V properties, and their leakage current was much less than that of the comparative pn. junction with Al/Si contact.