Ultra-shallow p+junction formed by photo-enhanced low-temperature epitaxy

Low-temperature Si epitaxy with heavy boron-doping using photo-enhanced processes was investigated. Under UV irradiation at 650 C a single crystal with a hole concentration of 1×10²⁰cm^-3was obtained. This epitaxial film had an abrupt impurity profile and high crystal quality. The UV irradiation enhanced the crystal growth and boron-doping in the low-temperature range. This technique enabled the fabrication of an ultra-shallow p⁺/n junction. This technique was applied to the base region of bipolar devices. A very thin, 65nm base with a carrier concentration of 1×10¹⁹cm^-3was realized. These characteristics made with this technique are attractive for application to very high-speed bipolar devices.