Effect of substrate bias on Si epitaxial growth using sputtering-type electron cyclotron resonance (ECR) plasma

Control of the energy of ions hitting the substrate during in situ cleaning and deposition was found to be very important for deposition of epitaxial Si thin film. This was studied by applying a substrate bias in the range of -30 to +30V in a sputtering-type electron cyclotron resonance (ECR) plasma system. During in situ cleaning, positive bias voltage reduced the ion bom bardment energy, and resulted in epitaxial deposition of Si crystal film ev en at a low gas pressure of 0.8 mTorr, at which epitaxial deposition was no t possible previously, During deposition, obvious improvements in the cryst allinity of the epitaxial Si film were achieved when the ion energy was I e duced by applying a positive bias. On the other hand, application of a nega tive bias for the deposition process resulted in amorphous film even when d eposition was performed at the hi,oh gas pressure of 1.7 mTorr, at which ep itaxial deposition was possible previously.