Selective low pressure chemical vapour deposition epitaxy using silane only for advanced device applications

Abstract

Selective epitaxial growth of silicon in windows opened in a mask is usually carried out using source gases in the Si–Cl–H system in low pressure chemical vapour deposition (LPCVD) systems. These gases offer good control over growth but are associated with mask distortion, which is intolerable in submicrometre device geometries. The silane only selective growth process possible in the Southampton University Microelectronics Centre (SUMC) LPCVD machine is highly selective, allowing growth of epitaxial layers four times thicker than the mask without lateral overgrowth. Surface facets are observed at the edges of 〈110〉 direction oxide features, in common with selective epitaxy by other techniques. The material under the facets is shown to include defects. Increased planarity can be obtained by orienting mask features along 〈100〉 directions, where faceting is not observed. The selectively grown material can be doped n type to give carrier concentrations from 2×1015 to 2×1019 cm−3, and p type from 1×1017 to 1×1019 cm−3. In terms of selectivity, planarity, and carrier concentration, the material produced by the SUMC LPCVD epitaxy machine is suitable for device production.MST/3221