Self aligned polysilicon gate contact.

摘要

A gate contact(e.g. 19) to a field effect transistor is opened over the source/drain region(e.g. 21) by forming polysilicon plugs(e.g. 15) between the gate structure(e.g. 5), which has a nitride top layer(e.g. 11), and the field oxide regions(e.g. 3). The contacts(e.g. 19) are formed by oxidizing and etching the gate structure(e.g. 5) and the polysilicon plugs(e.g. 15). An oxide layer(e.g. 31) may be deposited prior to the etching. The latter step opens a gate contact but does not expose the silicon in the plug(e.g. 15) because the different oxidation rates of the polysilicon plug(e.g. 15) and the material(e.g. 11) on top of the gate structure(e.g. 5) create oxide layers having different thicknesses. The nitride is now removed and contacts(e.g. 19) formed to the gate structure(e.g. 5).. <IMAGE>