Method of forming a semiconductor device having several gate levels

A method for forming a semiconductor device with at least two gate levels, comprising the following steps:

• a. on a seimiconductor substrate is depositied a dielectric layer, then a laeyr of material in which the gates of the first level are formed, and a dielectric layer;
• b. etching the two upper layers to pattern the gates of the first level;
• c. forming an insulating layer on the sides of the gates of the first level;
• d. depositing a second layer of material in which the gates of the second layer are to be formed;
• e. locally opening the second layer so as to expose a central portion of the dielectric layer covering a gate of the first level while leaving portions of the second layer above the sides of said gate of the first level;
• f. removing, through the opening in the second layer, the dielectric layer covering the gate of the first level, so as to expose the internal portion of the second layer overhanging the sides of the gate;
• g. etching, from inside the opening in the second layer and from outside said opening, portions of the second layer overhanging the sides of the gate of the first level.