Patent ID: 7176533

Claim:
A semiconductor device comprising: a semiconductor substrate including a conductive region on a surface thereof; an insulating layer on the semiconductor substrate, wherein the insulating layer has a contact hole therein exposing a portion of the conductive region wherein the insulating layer has first and second opposing surfaces such that the first surface of the insulating layer is adjacent the semiconductor substrate and the second surface of the insulating layer is spaced apart from the semiconductor substrate so that the first surface of the insulating layer is between the semiconductor substrate and the second surface of the insulating layer; and a polysilicon contact plug in the contact hole wherein at least a portion of the polysilicon contact plug is doped with an element having a diffusion coefficient that is less than a diffusion coefficient of phosphorus (P) wherein the polysilicon contact plug comprises, a first portion of the polysilicon contact plug in the contact hole, wherein the first portion of the polysilicon contact plug is doped with the element having the diffusion coefficient that is less than the diffusion coefficient of phosphorus (P), and a second portion of the polysilicon contact plug in the contact hole wherein the second portion of the polysilicon contact plug is doped with an element different than the element used to dope the first portion of the polysilicon contact plug, wherein the first portion of the polysilicon contact plug is between the second portion of the polysilicon contact plug and the substrate, wherein the second surface of the insulating layer spaced apart from the semiconductor substrate and outside the contact hole is free of the first portion of the polysilicon contact plug; wherein the second surface of the insulating layer spaced apart from the semiconductor substrate and outside the contact hole is free of the polysilicon contact plug, and wherein the polysilicon contact plug and the second surface of the insulating layer together define a substantially planer surface spaced apart from the substrate.