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Subjects Homework covered: Diffusion of solids Fick's first and second laws Diffusivity Ion Implantation Problem 1.
For fixed number of particles diffusing from a square concentration profile:
The diffusivity of phosphorous in silicon at 1100 degrees C is D~5x10-13 cm2/second, and the solid solubility of boron in silicon is ~2x1021 atoms/cm3. Write a short computer program to determine the diffusion profile of Boron into silicon at 1100 C after 20 minutes. You may want to use the numerical solution to Fick's second law, shown above. The closed form solution to this equation is the erf complementary function, and the diffusion profile can be solved with this closed form solution. For your homework, you should write up a forward finite difference code to solve this problem numerically. The kernel for the determination of a new concentration is provided on the next page. Problem 2. Boron ions are implanted into silicon with an a...