ELECTRON-CYCLOTRON RESONANCE ASSISTED LOW-TEMPERATURE ULTRAHIGH-VACUUM CHEMICAL VAPOR-DEPOSITION OF SI USING SILANE

Deposition of single-crystal homoepitaxial Si at low temperatures assisted by an electron cyclotron resonance (ECR) generated plasma using a mixture of helium and silane gases in an ultrahigh vacuum chemical vapor deposition (UHVCVD) chamber is reported. The pure silane gas is introduced into the UHVCVD chamber through a showerhead located above the substrate and is excited indirectly by the helium plasma brought downstream from the ECR chamber. At a chamber pressure of 5 x 10(-4) Torr epitaxial single-crystal Si can be obtained at a substrate temperature T(s) as low as 400-degrees-C. Variation of the deposition rate with respect to the microwave power, P-mu, at different temperatures suggests a hydrogen inhibited deposition process at low temperatures. At 460-degrees-C the deposition rate increases with P-mu below 60 W and saturates for P-mu beyond this value. On the other hand, at a T(s) of 610-degrees-C, this saturation effect is not observed and the deposition rate increases linearly with P-mu. In this plasma-assisted deposition, a much reduced T(s) dependence of the deposition rate is observed. We have used this deposition technique successfully in obtaining a Si3N4/(epi-Si) metal-insulator-semiconductor capacitor with an interface trap density of 2 x 10(10) eV-1 cm-2 as determined by the conductance method.