<p>A method of fabricating a semiconductor device is provided to constantly maintain an FICD(Final Inspection Critical Dimension) of a gate by simultaneously forming gates for low and high-voltage transistors. A substrate(110) with a low-voltage gate insulating layer formed in a first region and a high-voltage gate insulating layer formed in a second region is prepared. A gate conduction layer is formed on the low-voltage gate insulating layer and the high-voltage gate insulating layer. The gate conduction layer is etched to form a gate(113A) for a low-voltage transistor in the first region and a gate(113B) for a high-voltage transistor in the second region.</p>
