RELATIONSHIP BETWEEN TOTAL ARSENIC AND ELECTRICALLY ACTIVE ARSENIC CONCENTRATIONS IN SILICON PRODUCED BY THE DIFFUSION PROCESS

The dependences of diffusion coefficient of As, DAs, upon total As concentration, CT, and the relationships between CT and resistivity ρ for several diffusion temperatures are experimentally obtained for the As diffusion into p-type Si from doped polycrystalline-Si sources in the temperature range 850-1050°C. It is found that the relationship between CT and ρ is dependent upon diffusion temperature for CT above 1020 cm-3. The relationship between CT and electrically active As concentration at diffusion temperature, CA, i.e., CT=CA+(3. 2×10-6/n3i) C4A can be obtained, assuming that only electrically active As is mobile and is diffused by the single-level vacancy mechanism, and using the experimental result that the dependence of DAs/Di (Di is the intrinsic diffusion coefficient of As) upon CT/ni (n i is the intrinsic electron concentration) is not influenced by diffusion temperature. Using the above equation, it is found that the relationship between CA and ρ is independent of diffusion temperature, even for CA above 1020 cm-3, and can be approximated for CA above 1020 cm-3 by an empirical equation: ρ=8.7×104 C-2/5 A.