Layr-by-layr oxidation mechanism of hydrogen-terminated silicon surfaces and their interface structures

氢封端硅表面逐层氧化机理及其界面结构

基本信息

批准号：
04452177
负责人：
HIROSE Masataka
金额：
$ 4.42万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04452177/
关键词：
Silicon surface Surface microroughness Hydrogen-terminated Si Atomic step structure Layr-by-layr oxidation SiO_2 Si interface FT-IR-ATR AFM 原子間力顕微鏡表面モフォロジー layer by layer酸化 LOフォノン圧縮性応力表面酸化全反射赤外吸収分析

项目摘要

It was found that the wet chemical treatment in a pH-modified BHF(pH=3.8)solution or a 0.1%HF+1%H_2O_2 solution significantly reduces the surface microroughness of Si(100)wafers as demonstrated by a sharp SiH_2 stretching vibration peak accompanied with the weak SiH and SiH_3 peaks in FT-IR-ATR spectra. The suppression of anisotropic etching of Si with OH ions in a BHF solution or the selective removal of chemically reactive sites on the surfaces by the oxidation with H_2O_2 followed by oxide etching with HF is thought to be effective to produce the flat Si(100) surface. Taking into account the fact that the native oxidation rate of the flat Si(100)surface is significantly suppressed in the early stages of the oxidation compared with the case of rough Si(100)surfaces, it is likely that the native oxidation starts to proceed from the chemically reactive site such as microfacets and step edges on the surface.The Si(111)surface becomes atomically flat by 40%NH_4F treatment. The bilayr atomic step structure with a terrace width of a few hundreds nm is clearly observed by AFM.The AFM image of the Si(111)surface covered with a 4nm-thick thermal oxide is almost identical to the surface morphology before oxidation and the step structure is still observable on the oxide. Also, the Si surface after the removal of the oxide by dilute HF is similar to the intial surface. This suggests that the oxidation of the Si(111)surfaces proceeds through a layr-by-layr mechanism and this might be the case also for Si(100)surfaces. Furthermore, it was found that the infrared absorption peak due to the LO phonon mode originating from the Si-O-Si stretching vibration shows a considerable red-shift in the thickness range below 25A.This red-shift is well explained by the existence of the compressive stress near the interface.

结果发现，在pH值修改的BHF(pH=3.8)溶液或0.1%HF+1%H_2O_2溶液中进行湿化学处理显着降低了Si(100)晶片的表面微观粗糙度，表现为尖锐的SiH_2伸缩振动峰FT-IR-ATR 光谱中伴有弱的 SiH 和 SiH_3 峰。在 BHF 溶液中用 OH 离子抑制 Si 的各向异性蚀刻或通过用 H_2O_2 氧化然后用 HF 进行氧化物蚀刻选择性去除表面上的化学反应位点被认为是有效产生平坦 Si(100) 表面的方法。考虑到与粗糙 Si(100) 表面相比，平坦 Si(100) 表面的自然氧化速率在氧化早期阶段受到显着抑制，因此很可能自然氧化开始进行表面上的微面和阶梯边缘等化学反应位点。Si(111)表面通过40%NH_4F处理变得原子平坦。通过AFM可以清楚地观察到台阶宽度为数百nm的双层原子台阶结构。覆盖有4nm厚热氧化物的Si(111)表面的AFM图像与氧化前和台阶前的表面形貌几乎相同。在氧化物上仍然可以观察到结构。此外，用稀HF去除氧化物后的Si表面与初始表面相似。这表明 Si(111) 表面的氧化是通过逐层机制进行的，Si(100) 表面也可能是这种情况。此外，还发现，源自Si-O-Si伸缩振动的LO声子模式的红外吸收峰在低于25A的厚度范围内表现出相当大的红移。这种红移可以通过以下现象得到很好的解释：界面附近的压应力。