Silicon wafers with a deep p-n junction created by diffusion techniques are often used for discrete power and MOS power applications, as well as diode based devices. Diffused Wafers are created by diffusing a heavily doped region into a lightly doped wafer. The final thicknesses of both regions can be modified to meet the requirements of the device.
Diffused layers are now used more for very high voltage ( > 800V ) Power MOSFET devices. In this application, the Diffused Wafer (DW) may offer both performance and cost of ownership benefits over EPI wafers having EPI layer thicknesses in excess of 80um.
SEH has more than twenty years of experience manufacturing diffused wafers. The crystal growth and diffusion processes have been optimized to provide the best possible uniformity of both highly and lightly doped regions.
Example of DW equivalents to Thick EPI wafers