Gate stack process for high reliability dual oxide CMOS devices and circuits

摘要

1. A method of forming multiple oxide thicknesses on a base, according to the following steps: ;a) forming a layer of a first oxide on a base having an area, a, a first thickness and a first surface, the base having a top surface; ;b) depositing a first layer of polysilicon film having a second thickness on the first oxide layer, the first layer of polysilicon film having a second surface; ;c) removing a region of the first oxide and the first polysilicon, such that the base is exposed, and wherein a second thickness of oxide is desired over at least a portion of the region; ;d) forming a layer of a second oxide, having a third surface and a third thickness, on at least substantially all of the portion of the region where a second oxide thickness is desired, the third thickness not equal to the first thickness; ;e) depositing a second layer of polysilicon film having a fourth surface and a fourth thickness on at least the layer of second oxide such that the fourth thickness plus the third thickness is at least greater than the first thickness.