Infrared Reflection Absorption Spectroscopy of Selective Etching and Decomposition Stimulated by Synchrotron Radiation
- PDF / 2,110,709 Bytes
- 4 Pages / 604.8 x 806.4 pts Page_size
- 10 Downloads / 200 Views
length spectrum spans from about 1 nm to more than 100 n m with its peak at about 10 nm, which agrées roughly with the ionization energy of Si 2p core électrons. The photon flux energy on the substrate surface was about 2 W and the beam size was about 5 x 10 mm 2 . A pattern of polysilicon thin-film Unes deposited on SiO2/Si(100) was used as an etching mask for the Si0 2 etching. The etching rate of Si0 2 was 1.5 nm/min for 100-m A ring current. The etching pattern in Figure 1 shows several unique characteristics: complète stop on the Si(100) surface, no side etching, and sharp corner structures. The material selectivity of the etching observed hints at the etching m e c h a n i s m s . W h e n oxygen was not added, side etching of the Si0 2 was observed clearly, and the Si(100) single crystal was also etched. This indicates that
Tsuneo Urisu Introduction The study of processing stimulated by synchrotron radiation (SR) started about 13 years ago. 1 Unfortunately, for semiconductor processing, the reaction rate of this technique was considered to be too slow for practical applications. However the situation is rapidly changing as device dimensions shrink to the nanometer range, which requires high controllability and low defect densities, but is not so reliant on quick processing since much less material is involved. SR etching— which has a typical etching rate of 1 10 nm/min, capability of high-resolution etching due to the short wavelength of SR photons, high controllability, low damage production, and a clean reaction System—is considered to be extremely suitable for nanometer processing.1"4 The benefit of SR etching is that it has unique material selectivities. 1 However the mechanisms for the selectivity are not yet clarified. Considération of the future application of the SR process to nanometer structure fabrication is dépendent upon the development of in situ observation techniques that can evaluate the reaction surface at an atomic or molecular level. Recently we hâve developed an in si'fii observation technique:
46
infrared reflection absorption spectroscopy using buried métal layer substrates (BML-IRRAS), 5 " 7 which is especially suitable for in situ monitoring of beaminduced reactions on the semiconductor surface in high vacuum. In this article, the reaction selectivity of SR etching is investigated, and the spatial resolution is discussed briefly. Second, the SR-stimulated reaction of surface hydrogen on a Si(100) surface is investigated by in situ observation using BML-IRRAS.6 Similar reaction selectivity to that observed for etching has been found for the SR décomposition of SiH, S i H 2 , and SiH 3 . This means that the mechanisms of the material selectivity of SR etching can be clarified by investigating the molecular structure and the electronic states of thèse adsorbates and the SR irradiation effects on them.
SR Etching and Material Selectivity Figure 1 shows a line and space pattern formed by SR etching using SF6 + 0 2 with about 0.1-Torr total pressure.' Experiments were conducted at the BL1
Data Loading...
