Method for forming high resistance resistor with integrated high voltage device process

摘要

The method for forming high voltage device combined with a mixed mode process use an un-doped polysilicon layer instead of the conventional polysilicon layer. In the high resistance area, the ion implant is not used until the source region and the drain region are formed. A resistor is formed by etching oxide-nitride-oxide layer and performing ion implant process by using BF2 radical to the un-doped polysilicon layer to control the resistance. Then multitudes of contact are formed, wherein the high dosage of BF2 implant would reduce resistance between contacts and resistor.