Koichi Kitahara

Crystal Defects in Epitaxial Layer on Nitrogen-doped Czochralski-grown Silicon Substrate (II) –Suppression of the Crystal Defects in Epitaxial Layer by the Control of Crystal Growth Condition and Carbon Co-doping–

Two types of crystal defects, stacking fault induced by a nitrogen-doped substrate (N-SF) and elliptical pit (E-pit), are generated in the epitaxial layer due to grown-in defects in a nitrogen-doped Czochralski-grown silicon (CZ-Si) substrate. We investigate the dependence of N-SF and E-pit formation on the quality of nitrogen-doped substrates. It was revealed that the control of both nitrogen concentration and crystal growth parameter of the CZ-Si ingot is effective for suppressing N-SF and E-pit formation. We also examined crystal defect in the epitaxial layer on a nitrogen and carbon co-doped substrate, which is the other candidate for realizing the epitaxial wafer having a high intrinsic gettering ability. It was clarified that carbon co-doping in addition to nitrogen doping suppresses N-SF and E-pit generation.

Growth of SiC Films using Tetraethylsilane

Tetraethylsilane (TES, Si(C2H5)4) was used as a safety source for the growth of SiC thin films on Si(111) substrates by chemical vapor deposition method. Carbonization of Si substrate was carried out to form a buffer layer using C3H8 gas. SiC thin films were grown at various substrate temperatures and TES flow rates for the purpose of forming carbon-free SiC films. The excess carbon incorporated in the film due to high C/Si ratio was removed by means of decreasing the TES flow rate. Moreover, high quality SiC films were grown at high growth temperature of 1350°C.

Crystal defects in epitaxial layer on nitrogen-doped Czochralski-grown silicon substrate (I): Investigation of the crystallographic structure

We have investigated crystal defects in the epitaxial layer on nitrogen-doped Czochralski-grown silicon (CZ-Si) substrate. It was found that two types of crystal defects are generated in the epitaxial layer on the nitrogen-doped CZ-Si substrate. One is revealed to be a stacking fault and the other is a perfect dislocation pair. The origin of these defects is a rod like void and a dislocation loop in the nitrogen-doped CZ-Si substrate. We discuss the formation mechanism of the crystal defect in the epitaxial layer caused by the grown-in defect.

Study of plasma-nitriding process in Si with in situ spectroscopic ellipsometry

In situ spectroscopic ellipsometry was applied to plasma-nitriding process in single crystalline Si. It was shown that plasma nitridation of Si takes place even at room temperature and the plasma-damaged layer is recovered to single crystalline layer in heating-up process to 1300 K. The disappearance of oxide layer from Si surface during heating-up process at ∼1200 K was observed by in situ model analysis, which was used to determine the start timing of plasma nitridation.