A process for producing a capacitor integrated into an electronic circuit comprises the formation of a trench in a substrate through a conductive portion similar to an MOS transistor gate. Alternating conductive, insulating and conductive layers are deposited inside the trench T in order to form a lower electrode, a dielectric and an upper electrode of the capacitor, respectively. The conductive portion is used to electrically connect the lower electrode to other electronic components of the circuit without an additional cost with respect to the connection of the circuit transistors.