Method for forming low-voltage CMOS transistors with a thin layer of gate oxide and high-voltage CMOS transistors with a thick layer of gate oxide

摘要

The low-voltage, e.g., 2.5-volt, transistors that support the logic operations of a CMOS device are formed to have a thin layer of gate oxide, while the high-voltage, e.g., 3.3 or 5-volt, transistors that support the analog operations of the device are formed to have a thick layer of gate oxide in a cost-effective process flow that requires only one additional masking step over a conventional double-poly CMOS process.