SOI STRUCTURE HAVING REDUCED PARASITIC CAPACITANCE AND PRODUCTION THEREOF

摘要

PROBLEM TO BE SOLVED: To reduce parasitic capacitance by forming a doped region directly adjacent to an isolation layer in an underlying silicon substrate using a dopant having a conductivity opposite to that of a silicon substrate. SOLUTION: In general, an isolation layer 104 is a buried oxide layer just like an SOI structure 1100. An active semiconductor layer 102 normally contains doped N type or P type silicon and has active and passive circuit elements and an interconnecting contact region. The isolation layer 104 is formed in a substrate 10. In several embodiments, the isolation layer is formed of sapphire or other dielectric material 104. A doped layer 210 (or region) is formed in a substrate 106 contiguously to the isolation layer 104. When the substrate 106 has P type conductivity, the doped layer 210 has N type conductivity.