The distribution and characteristics of remnant orebodies in Piaotang mining area are introduced in this paper, some principles which should abide by stoping of remnant orebodies are put forward.

The influences of five parameters(the doses of the drift,the length of the field plate,the thickness of field oxide layer,the thickness of gate oxide layer,the doses of the channel) on the nonlinear Cd were discussed.

A novel analytic model on the relationship about the surface voltage and the PN junction electric field with the ion dose in the drift of gate off MOS is presented.

By using the software of ISE and the patterned SOI LDMOS with good performance,the relationship between transconductance and the thickness of gate oxide and SOI layer ,the concentration of the drift region and the channel are all discussed in this paper.

The influence of the parameters of the drift region,channel region and field plate on the breakdown voltage of the high voltage PLDMOS has been investigated by using the simulators Tsupre-4 and Medici.

The model includes physical models for nonuniformly doped channel,non-linear drift region resistance and voltage-depending non-linear parasitical capacitances.