One integrated circuit design calls for diffusing boron into very high purity silicon at an elevated temperature. It is necessary that at a distance 0.2 μm from the surface of the silicon wafer, the room-temperature electrical conductivity be 1.2 × 103 (Ω-m)-1. The concentration of B at the surface of the Si is maintained at a constant level of 1.0 × 1025 m-3; furthermore, it is assumed that the concentration of B in the original Si material is negligible, and that at room temperature the boron atoms are saturated. Specify the temperature at which this diffusion heat treatment is to take place if the treatment time is to be one hour. The diffusion coefficient for the diffusion of B in Si is a function of temperature as

Doli)-24 104 exp(-347RT D(m2/s) = 2.4 104 exp