Experimental Study of Photochemical Deposition in a Condensed Phase on a Cryogenic Substrate

低温基底上凝聚相光化学沉积的实验研究

基本信息

批准号：
07555041
负责人：
ENDO Katsuyoshi
金额：
$ 6.08万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555041/
关键词：
photochemical reaction deposition condensed phase cryogenic substrate excimer laser silane crystalline silicon two-photon absorption μc-Si ダイヤモンド合成無定形炭素 ArF KrF 凝集用原子状水素ダイヤモンド成膜

项目摘要

We have studied photochemical deposition in a condensed phase. In the experiment, liquid silane (SiH_4) on a cryogenic substrate is irradiated with KrF and ArF excimer laser. The deposition film is characterized by Raman scattering, scanning electron microscopy, transmission electron microscopy and transmission electron diffraction. The film is composed of many rod-like crystalline silicon (c-Si) products. Their diameter and height are 400-500 nm and 500-700 nm, respectively. It is remarkable that the rod-like c-Si has grown on the cryogenic substrate. Therefore, we consider that the liquid-solid interface reaction plays an important role in the crystallization growth. In other words, the growth from the c-Si surface is necessary or crystallization. We propose the following deposition mechanism. Namely, (1) SiH_4 molecule photoexcited by a two-photon absorption would be dissociated into a SiH_3 radical and an atomic hydrogen. (2) A created atomic hydrogen extracts a hydrogen atom from the "neighboring" molecule, and forms a hydrogen molecule H_3. (3) The remaining radicals combine and form a Si-Si bond. A similar reaction occurs successively and the generated hydrogen silicides (Si_xH_y) are deposited on the substrate. In the second stage, the formed nuclei (Si_xH_y) grow to be c-Si through the one-photon absorption. Generally speaking, as a molecule becomes larger, its absorption edge shifts to longer wavelength. Therefore, the large hydrogen silicides are excited and react easily with "neighboring" SiH_4 through the one-photon absorption process. This technique solves general problems in photochemical vapor deposition techniques, such as deposition on the optical window, thermal damages of the substrate and the low deposition rate in the gas phase.

我们研究了凝聚相的光化学沉积。实验中，低温基底上的液体硅烷（SiH_4）被KrF和ArF准分子激光照射。通过拉曼散射、扫描电子显微镜、透射电子显微镜和透射电子衍射对沉积薄膜进行表征。该薄膜由许多棒状晶体硅（c-Si）产品组成。它们的直径和高度分别为400-500 nm和500-700 nm。值得注意的是，棒状 c-Si 已在低温衬底上生长。因此，我们认为液固界面反应在结晶生长中起着重要作用。换句话说，从c-Si表面的生长是必要的或者是结晶。我们提出以下沉积机制。即，(1)通过双光子吸收光激发的SiH_4分子将解离成SiH_3自由基和原子氢。 (2) 生成的原子氢从“邻近”分子中提取氢原子，形成氢分子H_3。 (3)剩余的基团结合并形成Si-Si键。类似的反应连续发生，生成的硅化氢(Si_xH_y)沉积在衬底上。在第二阶段，形成的核（Si_xH_y）通过单光子吸收生长为c-Si。一般来说，随着分子变大，其吸收边会向更长的波长移动。因此，大的硅化氢很容易被激发并通过单光子吸收过程与“邻近”的SiH_4发生反应。该技术解决了光化学气相沉积技术中的普遍问题，例如光学窗口上的沉积、基底的热损伤以及气相沉积速率低等问题。