Microstructure of Si Films Deposited on Si(100) Surfaces by Remote Plasma-Enhanced Chemicalvapor Deposition, Rpecvd: Dep
- PDF / 375,008 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 56 Downloads / 213 Views
MICROSTRUCTURE OF Si FILMS DEPOSITED ON Si(100) SURFACES BY REMOTE PLASMA-ENHANCED CHEMICALVAPOR DEPOSITION, RPECVD: DEPENDENCE ON PROCESS PRESSURE AND SUBSTRATE TEMPERATURE S. HABERMEHL, S. S. HE, Y. L. CHEN AND G. LUCOVSKY Departments of Physics, Materials Science and Engineering, and Electrical and Computer Science, North Carolina State University, Raleigh, NC 27695-8202.
ABSTRACT The microstructure of Si thin films, deposited on in-situ cleaned Si(100) surfaces by remote plasma-enhanced chemical-vapor deposition (RPECVD), is dependent on the process pressure, substrate temperature and H2 flow rate. Surface characterization by on-line low energy electron diffraction, LEED, has been used to detect changes in the character of the deposited films which can either be amorphous, microcrystalline or crystalline, hereafter designated as a-Si, gc-Si, and c-Si, respectively. We have used these results to generate phase diagrams for the Si microstructure as a function of the process pressure and substrate temperature, including the flow rate of H2 as an additional deposition parameter. INTRODUCTION The development of low temperature, and/or low thermal budget, processes for future generations of advanced VLSI and ULSI devices is considered to be critically important. Remote PECVD is one such process that has shown promise for low temperature deposition of dielectric and epitaxial Si films [1-3]. In an effort to understand the interaction of the many process variables encountered in RPECVD, deposition phase diagrams, covering a relatively wide range of pressures and temperatures, have been generated. Of particular interest are the conditions necessary to promote defect free homoepitaxial growth. The role of hydrogen, in the gas phase as well as on the surface, is observed to play a critical part in determining the
structure of the deposited Si films. Representative chemical reactions for the desorption and adsorption of H from the Si(100) surface, dissociation of SiI14 in the deposition reaction, and gas phase recombination of excited species are all considered as a means to explain the observed film structures. The range of pressures and temperatures considered in this study are 50-500 mTorr and 25-450'C, respectively. As an additional variable, H2 flow rates of 0 and 25 sccm have been studied. EXPERIMENTAL A multi-chamber RPECVD system, depicted schematically in Fig. 1, was used for predeposition surface cleaning, Si deposition and post-deposition surface analysis [4]. The system, capable of handling 3" wafers, consists of three remote plasma processing chambers, one metallization chamber and one UHV surface analysis chamber, all connected to a central load-lock chamber. The three remote plasma chambers are individually dedicated to separate tasks: i) oxide/nitride deposition, ii) Si deposition and iii) reactive ion etching/plasma cleaning. The metallization chamber, which is operational but not as yet connected to the system, is designed for the sputter deposition (DC or RF) of metal contacts to films deposited in vac
Data Loading...
