STUDY OF INITIAL STAGE OF SILICIDE FORMATION ON HYDROGEN-TERMINATED SILICON SURFACES

本研究的目的是研究氢封端硅表面硅化物的初始形成机制。首先，我们利用飞行时间型电子刺激脱附谱（TOF-ESD）研究了氢原子在洁净硅表面的吸附和脱附特性。原子氢封端的硅表面是非常稳定的，在原子层外延过程中具有表面活性剂效应。在2000朗缪尔的氢气氛中热裂解产生的氢原子终止了（111）和（100）面的硅表面。利用自行研制的TOF-ESD对硅表面吸附氢进行了原位检测。本文通过测量质子脱附的阈电子能、脱附质子的动能分布和不同氢暴露量下的脱附产额，研究了氢原子在洁净硅表面上的吸附特性。结果表明，质子在第一次激发时的脱附机制符合Menzai-Gomer-Redhead模型。此外，为了与硅化镍表面进行比较，还利用TOF-ESD研究了氢和CO在镍表面上的吸附，发现在硅表面上外延生长的镍在氢终止表面和非终止表面上具有不同的生长模式。也就是说，通过加热，沉积在由氢终止的Si（100）上的镍原子比未终止的Si（100）更快地扩散到体中。Ni/H/Si（100）-端接表面比未端接表面富镍，氢为氢，在此表面上的吸附量比未端接表面少。

A purpose of the present investigation was a study of initial formation mechanism of silicide on hydrogen-terminated silicon surfaces. Firstly we investigated adsorption and desorption characteristics of atomic hydrogen on clean silicons surface by using a tim-of-flight type electron stimulated desorption spectroscopy (TOF-ESD). It is believed that the terminated silicon surface by atomic hydrogen is very stable and has a surfactant effect during atomic layr epitaxy. Both of silicon surfaces of (111) and (100) planes were terminated by atomic hydrogen which generated by thermal cracking in hydrogen atomosphere of 2000 Langmuirs. The TOF-ESD which has been developed in our institute was used in-situ in order to detect the adsorbed hydrogen on silicon surfaces. Adsorption characteristtics of atomic hydrogen on clean silicon surfaces have been investigated by measuring the threshould electron energy for proton desorption, kinetic energy distribution of the desorbed protons and desorption yields for various hydrogen exposures. As a result a desorption mechnism of the proton at the first onset is due to Menzai-Gomer-Redhead model. Beside, adsorptions of hydrogen and CO on nickel surfaces were also investigeted by TOF-ESD in order to compare the nickel silicide surface.Epitaxial growth of nickel on silicon surface had different growth modes between hydrogen terminated surfaces and non-terminated surface. Namely, deposited nickel atoms on Si(100) terminated by hydrogen was diffused more quickly into the bulk than unterminated Si(100) by heating. A Ni/H/Si(100)-tereminated which was nickel rich than the unterminated one, and hydrogen was hydrogen was adsorbed less on this surface than untermianted surface.