Selective epitaxial growth of Si and SiGe/Si heterostructures in a hot-wall tubular low pressure chemical vapor deposition system

Over the past several years, advances in the SiGe technologies have shown impressive potential for fabricating high-performance SiGe/Si heterojunction devices. The objective of this research work was to explore the possibility of using a conventional tubular hot-wall low pressure chemical vapor deposition (LPCVD) system to selectively grow SiGe epitaxial layers. This conventional LPCVD system was proposed as a low cost alternative for SiGe epitaxial growth, offering high wafer capacity, good temperature control, and excellent growth rate uniformity across the wafer. By utilizing LPCVD, SiGe selective epitaxial growth (SEG) could be easily integrated with current silicon processes so that heterojunction structures would be more manufacturable. The LPCVD system, the process requirements, and the results of SiGe SEG are reported. Selective epitaxial growth (SEG) of Si and SiGe on patterned silicon substrates, using a tubular hot-wall LPCVD system, has been demonstrated. Dichlorosilane $\rm(SiH\sb2Cl\sb2)$ and germane (GeH$\sb4)$ were used as the reactant gases with hydrogen as a carrier gas, with no addition of HCl needed to achieve selectivity in quality epitaxial growth of SiGe. Nomarski microscopy showed good selectivity with no nucleation occurring on the SiO$\sb2$ areas. A low defect silicon buffer layer grown under SEG conditions immediately after the H$\sb2$ bake greatly improved the quality of SiGe SEG. TEM studies showed that good quality SiGe epitaxial layer could be grown on the Si SEG buffer layer over a range of growth conditions $\rm(700\sp\circ