Characterization of SIMOX and ZMR materials by spreading resistance and point contact current voltage techniques

Summary form only given. Spreading resistance measurements on as implanted, unannealed SIMOX substrates showed pile-up of dopant below the implanted region over a depth of 300 nm. The dopant pile-up disappeared after the high-temperature (1300°C, 6 hours) anneal. The SIMOX Si films (both n and p-type) after the high-temperature anneal were found to be nonuniformly doped. The dopant concentration steadily decreased by two orders of magnitude while going from the surface to about 50 nm above the buried oxide and then it dropped to the insulator level (instrument limit) in the last 50 nm. Spreading resistance measurement on 300 nm zone melt recrystallized (ZMR) silicon films showed them to be n-type with initial carrier concentration of less than 10¹³/cm³. The carrier concentration decreased slowly in the top 250 nm and then it rapidly dropped to the lower detectability limit (10¹⁰/cm³) in the last 50 nm as the buried insulator was approached. Local inhomogeneities or precipitates in the buried oxide result in conducting paths and can be observed by PCIV technique. PCIV breakdown characteristics measured on SIMOX substrate surface before high temperature anneal showed a snap-back while no snap-back was seen in the sample after high temperature anneal. These measurements indicate the possibility of using PCIV (with or without breakdown voltage mapping of a SIMOX substrate) as a tool to characterize the buried oxide quality