METHOD FOR FORMING POLY PLUG OF THIN FILM TRANSISTOR

PURPOSE: A method for forming a poly plug of a thin film transistor is provided to enhance reliability of the thin film transistor by reducing a step difference without a loss of a poly plug. CONSTITUTION: An interlayer dielectric(32) is deposited on a substrate(31). A contact hole is formed by etching the interlayer dielectric(32). A polysilicon layer is deposited on the interlayer dielectric(32) including the contact hole. The thickness of the polysilicon layer is reduced by etching the polysilicon layer. A photoresist layer is deposited on the polysilicon layer. The photoresist layer is patterned by performing an exposing process and a developing process. A poly plug(33a) is formed by etching the polysilicon layer. A poly gate(35) and a gate oxide layer(36) are formed by depositing and etching a polysilicon layer and an oxide layer. A poly channel layer(37) is formed by depositing a silicon layer on the gate oxide layer(36). A part of the poly gate(35) is exposed by patterning the poly channel layer(37).