SIMOX-MATERIAL QUALITY IN A SEMIINDUSTRIAL PRODUCTION

Based on the results of five years of research on the SIMOX process, a complete facility for production of SIMOX wafers on a semi-industrial basis has been set up at LETI. This facility which is located in a class-100 clean room comprises an EATON NV 200 implanter, a high-temperature annealing furnace and nondestructive characterization tools. As-implanted wafers are characterized from the point of view of particles, implanted oxygen dose and dose homogeneity. After annealing, the silicon overlayer thickness and homogeneity are measured. Destructive characterization tools such as nuclear reaction analysis (NRA) for absolute oxygen-dose monitoring and secondary-ion mass spectrometry (SIMS) for metallic-impurity controls are also used. TEM and XTEM are used to monitor the dislocation density and the Si/SiO2 interface quality. The SIMOX wafers have typically a 200 nm thick silicon layer on top of a 380 nm thick buried oxide and a dislocation density smaller than 5 x 10(5) cm-2. This facility is also used for research on SIMOX material, with a view to producing very thin (< 100 nm) silicon overlayers that will be required for the future CMOS/SOI circuit generations.