Surface Microchemical Reactions during Hydrogenated Silicon Growth Studied by In-situ ESR Technique
- PDF / 166,469 Bytes
- 12 Pages / 595 x 842 pts (A4) Page_size
- 51 Downloads / 178 Views
Surface Microchemical Reactions during Hydrogenated Silicon Growth Studied by In-situ ESR Technique
Satoshi Yamasaki Joint Research Center for Atom Technology (JRCAT) -National Institute for Advanced Interdisciplinary Research (NAIR) 1-1-4 Higashi, Tsukuba-City, Ibaraki 305-9562, Japan ABSTRACT The in-situ ESR technique is applied to a plasma-enhanced chemical vapor deposition (PECVD) system in order to investigate the surface microchemical reactions during the growth of hydrogenated amorphous silicon (a-Si:H) and plasma treatments of H2 and Ar gases on aSi:H. The growth model of a-Si:H and the role of H atoms on a-Si:H films are discussed using the experimental results. The recent results on the dynamic surface reactions of crystalline silicon with oxygen molecules in an ultra-high-vacuum ESR system are introduced.
INTRODUCTION The electron-spin-resonance (ESR) technique has been applied for a variety of semiconductor materials, and provides important information on the defect structure in a bulk. However, it has been not easy to get information on the reacting surface because of the experimental difficulties for surface treatments and experimental setups matching an ESR cavity. Recently, much knowledge about such surface treatment and deposition techniques has been obtained. This knowledge has led to new experimental possibilities of in-situ ESR techniques of surface microchemical reactions in semiconductors. One is the in-situ observation of chemical vapor deposition (CVD) processes using a remote plasma technique [1] and another is the surface reactions in single crystalline semiconductors using an ultra-high-vacuum (UHV)-ESR system [2]. In the growth of a-Si:H, dangling bonds (dbs) in a subsurface region should play a crucial role as reaction sites for precursors to bond with the surface. Elementary reactions of film growth are equivalent to the processes of termination, annihilation and creation of dbs. However, no information has been reported on the dbs during film growth before our works [37], although other structural information was obtained by various techniques such as infrared reflection absorption spectroscopy [8], spectroscopic ellipsometry [9], and scanning probe microscopy [10]. Therefore, in-situ ESR measurements during film growth and plasma treatment provide valuable information for understanding growth kinetics. Initial attempts to measure defect centers by the ESR technique during film growth were carried out by Johnson et al. for a-Si:H film growth using a remote plasma system, and they detected ESR signals associated with hydrogen atoms in the gas phase and E' centers of a silica-glass tube [11].
A1.1.1
However, no Si db centers of a-Si:H (db centers) could be detected, perhaps because of the paucity of deposited material. We tried in-situ ESR measurements during deposition of hydrogenated amorphous silicon (a-Si:H) for a wide range of deposition conditions and different geometrical relationships between the ESR cavity and the remote plasma system. Finally we have succeeded in depositing
Data Loading...
