Dear MEMS colleague: I use spin-on boron liquid dopant on silicon wafer.and after about 20hrs furnace diffusion. I found that: in the center area of the wafer i get lower resistivity than in the edge area of the wafer. what casue Resitivity difference: in the spin-on dopant or in diffusion furnace? what is the reason of it. Thanks. JL ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com