Low temperature in situ boron doped Si epitaxial growth by ultrahigh vacuum electron cyclotron resonance chemical vapor deposition

Boron-doped silicon epitaxial layers were grown by ultrahigh vacuum electro n cyclotron resonance chemical vapor deposition at 440-510 degrees C. Refle ction high-energy electron diffraction and transmission electron microscopy (TEM) were used to study the effect of boron doping on the crystalline qua lity of;silicon epitaxial layers. At growth conditions where undoped defect -free Si epitaxial layers were successfully obtained at 440 degrees C, in s itu boron-doped epitaxial layers were replete with twins. However, at condi tions with increased ion energy flux and at a higher temperature, 470 degre es C, no twins were observed. TEM analysis revealed the presence of an amor phous phase in the twinned epitaxial layers. It is believed that the amorph ous phase formation, presumably from the reaction between B and O during th e doping process, appeared to hinder the growth of the epitaxial layer, lea ding to degradation of the Si crystalline quality. Defect-free boron-doped Si epitaxial layers were able to be obtained by suppressing the amorphous p hase formation at conditions with increased growth temperature and higher i on energy flux. (C) 1999 American Vacuum Society. [S0734-211X(99)00101-8].