Method for manufacturing contactless module having an antenna coil with finely adjustable inductance

A method for manufacturing a contactless module, comprising the steps of:

• depositing a first electrically conductive layer on a first face of a wafer;
• forming an antenna coil by etching the first layer, the antenna coil including turns of increasing rank from the outside toward the inside of the antenna coil, including an outer turn of rank 1 and an inner turn of rank N, the inner turn being connected to an internal connection pad and the outer turn being connected to an external connection pad;
• attaching a microcircuit to the first face of the wafer, in a central area of the antenna coil delimited by a turn of the antenna coil;
• and
• connecting first connection terminals of the microcircuit to connection pads of the antenna coil, via wires;
• wherein the first layer is etched in such a way that the external and internal connection pads of the antenna coil are formed in the central area of the antenna coil, the antenna coil comprising a bypass area in which each turn bypasses the external connection pad via the central area,
• wherein the first layer is etched in such a way that:
• the antenna coil comprises a first group of turns of ranks 1 to E, having substantially the same distance between turns, the turn of rank E being the inner turn of the first group of turns, E being at least equal to 4;
• the central area is delimited by the contour of the inner turn of the first group of turns;
• and
• the antenna coil comprises a second group of at least two turns of ranks E+1 to N, which extends within the central area, each turn of the second group of turns comprising portions of turns which are at variable distances from the turn of preceding rank, said distances being comprised between said distance between turns and several times the distance between turns.