Low temperature silicon epitaxy in a single-wafer RTP reactor with microwave heating

Abstract

Chemical vapour deposition (CVD) of expitaxial silicon was carried out in a single wafer, rapid thermal processing (RTP) reactor chamber. The silicon wafer was heated volumetrically by microwaves. The silicon growth was realised by thermal pyrolysis of SiH4 at ~700°C on blank and patterned silicon wafers. The reactor chamber was equipped with a molecular-turbo pump backed by a booster/rotary pump package; the base pressure of the reactor chamber was better than 10−5 Pa. Silicon deposition was carried out in the pressure range of 1-20 Pa. Prior to deposition, the system was purged with H2 at 50 Pa, either at 700°C for 15 min or at 900°C for 15 sec. A typical epitaxial silicon growth rate was 5 nm/min at 700°C. The quality of the epitaxial silicon layers, studied by means of Rutherford backscattering spectrometry (RBS), x-ray diffraction (XRD), and cross-sectional scanning electron microscopy (XSEM), was found to be sensitive to a number of deposition parameters, including substrate temperature, gas flow rate and surface cleaning.