A method for manufacturing a transistor is provided, the transistor including a gate disposed above an underlying layer of a semiconductor material, the gate including at least one first flank and at least one second flank, and a gate foot disposed under the gate in the underlying layer and protruding relative to a peripheral portion of the underlying layer, the peripheral portion surrounding the gate foot; and the method including forming a selectivity layer obtained from an original layer and disposed only above the peripheral portion of the underlying layer, and selective etching, with respect to the selectivity layer, of the material of the original layer so as to etch the gate foot.