Process flow to integrate high and low voltage peripheral transistors with a floating gate array

Abstract

The invention comprises an integrated circuit including integral high and low-voltage peripheral transistors and a method for making the integrated circuit. In one aspect of the invention, a method of integrating high and low voltage transistors into a floating gate memory array comprises the steps of forming a tunnel oxide layer outwardly from a semiconductor substrate, forming a floating gate layer disposed outwardly from the tunnel oxide layer and forming an insulator layer disposed outwardly from the floating gate layer to create a first intermediate structure. The method further includes the steps of masking a first region and a second region of the first intermediate structure leaving a third region unmasked, removing at least a portion of the insulator layer, the floating gate layer and the tunnel oxide layer from the third region and forming a first dielectric layer disposed outwardly from the substrate in a region approximately coextensive with the third region. The second region and the third region are masked, leaving the first region unmasked. Then, at least a portion of the insulator layer, the floating gate layer and the tunnel oxide layer is removed from the first region. A second dielectric layer is formed outwardly from the substrate and the first dielectric layer in a region approximately coextensive with the first region and the third regions, respectively.