Development of atomically-controlled oxidation techniques for ultra-thin gate oxide films

我们已经确定了硅表面初始氧化过程和硅表面结构分离在硅表面D22和D2薄膜中使用高分辨率电子能量损失光谱（HREELS）、扫描隧道显微镜和扫描隧道光谱（STM/STS）的氢和影响。主要内容如下所示。（1）在H-终结的硅（100）表面上，发现了通过改变债券角度来增强硅-O-硅结合结构的放松的硅-O-硅结合结构。更好的是，氧化物表面上的Si-H债券更稳定在O吸引他们的两个Si-Si背面债券上。要说的是，在硅表面上和在氧化物电影中的结合能量比在硅表面上的能量要大。（2） In the case of the oxidation of pイイD1+イエD1-Si（100） surfaces， the impurity concentration influences the relaxation of SiOイD22イエD2 structures。B原子能增强Si-O-Si结构放松。这种现象可能不会被硅原子和B原子之间的交换所捕获，但被称为费米水平的电子效应所捕获。（3）紧张素与H-终结硅上的氧化物（111）表面相对于硅-O-硅结合角度的放松。这种放松在1 ML的氧化物强度下被惊人地观察到，在增加后束中有两个或三个O原子的Si-H物种的数量。作为一个结果，带有Si-H键的表面硅原子被提升了。（4） On the pie D1+ D1-Si（100） surface， specific structures由surface segregated B atoms are observed，it is found out that there are two kind of structures。B原子可以稳定O Adsorption站点，在一个低影响度集中的硅表面上是不稳定的。这是一个强有力的建议，即O广告站点是可控制的，可以用B集中改变表面应变。

We have clarified the effects of hydrogen and impurities on the initial oxidation processes of Si surfaces and the structural relaxation in SiOィイD22ィエD2 films using high-resolution electron energy loss spectroscopy (HREELS), scanning tunneling microscopy and scanning tunneling spectroscopy (STM/STS).The principal conclusions are shown below.(1) On a H-terminated Si (100) surface, it was found that Si-H bonds enhance the relaxation of Si-O-Si bonding structures by changing the bond angle. Moreover, Si-H bonds on the oxidized surface are more stable by the O adsorption on their two Si-Si back bonds. That is to say, the binding energy of the Si-H bonds on and in the oxide film is larger than that on Si surfaces.(2) In the case of the oxidation of pィイD1+ィエD1-Si (100) surfaces, the impurity concentration influences the relaxation of SiOィイD22ィエD2 structures. B atoms enhance the Si-O-Si structural relaxation. This phenomenon may be caused not by the exchange between Si atoms and B atoms but by the electronic effect such as Fermi level.(3) The strain accompanying the oxidation on H-terminated Si (111) surfaces is relaxed by enlarging the Si-O-Si bond angle. The relaxation is remarkably observed at an oxide thickness of 1ML, where the amount of Si-H species with two or three O atoms in the back bonds increases. As a result, surface Si atoms with a Si-H bond are lifted up.(4) On the pィイD1+ィエD1-Si (100) surface, specific structures formed by surface-segregated B atoms are observed and it was found out that there are two kind of structures. B atoms stabilize an O adsorption site, which is unstable on a Si surface with a low impurity concentration. This finding strongly suggests that the O adsorption site is controllable by changing the surface strain with the B concentration.