Development of Thin-Film Active Devices on an Improved Insulating Substrate.

摘要

The conditions for epitaxial growth of silicon on single-crystal magnesium aluminate spinel have been further refined in an effort to achieve electrical properties in the semiconducting thin-film on the insulating substrate which are desired for application of this materials system to the fabrication of improved integrated devices. The deposition parameters investigated have been the growth temperature,the growth rate,and the purity of the source gases. The optimum conditions for deposition of silicon-on-spinel are considerably different from those used for the deposition of silicon-on-sapphire. Significant improvements in the electrical properties have been achieved as the result of optimizing the deposition conditions. Silicon films have been prepared with bulk mobilities at doping levels (p-type) of 5 x 10to the 15th power /cc. The mobilities change approximately 10% after a 1-hour thermal oxidation at 1100C. These represent the highest mobilities,at this carrier concentration,that have ever been achieved for silicon on insulating substrates. It has been found that the lateral diffusion of dopants in the silicon near the silicon-substrate interface is significantly less in silicon-on-spinel than in silicon-on-sapphire. This permits closer spacing of active components in integrated circuits on silicon-on-spinel. Minority-carrier lifetimes have been measured as high as 45nsec in the silicon film on spinel. This is the highest lifetime that has been realized in silicon on an insulating substrate. Preliminary investigations have been made in diode and MOS transistor structures with encouraging results. (Author)