Computer-Aided Design of One-Dimensional MOSFET Impurity Profiles

A new numerical method for automated design of MOSFET impurity profiles is presented. For a discrete mesh, the method efficiently calculates the gradient of electrostatic potential at each point in the semiconductor with respect to changes in the impurity concentration at every other point in the semiconductor. The gradient information is then used to adjust the profile to achieve a desired conduction condition in the device. Profile templates may be used to control the shape of profiles used during the design of enhancement- and depletion-mode threshold voltages. Profiles may also be designed to give a specified depletion-mode MOSFET conduction level or can be optimized for minimum substrate sensitivity or temperature dependence.