METHOD FOR FORMING DUAL GATE OF SEMICONDUCTOR DEVICE

摘要

A method for forming a dual gate of a semiconductor device is provided to obtain stable device characteristics by preventing the formation of a depletion layer in a polysilicon layer under a following heat treatment using multi-step boron ion implantations and CMP. A semiconductor substrate(10) is defined with a first region for an NMOS transistor and a second region for a PMOS transistor. A gate insulating layer(11) is formed on the entire surface of the resultant structure. A gate conductive layer doped with an N type dopant is deposited on the gate insulating layer. Multi-step ion implantations are performed on the resultant structure by using a mask capable of enclosing the first region alone to implant a P type dopant into the gate conductive layer of the second region. A planarizing process is performed on the resultant structure to remove a damaged layer(16) from the gate conductive layer of the second region.