Enhanced method of introducing a stress in a transistor channel by means of sacrificial sources/drain regions and gate replacement

Method of making at least one strained channel semiconducting structure for a transistor, comprising the following steps:

• form a sacrificial gate block and insulating spacers arranged in contact with the lateral faces of the sacrificial gate block, on a semiconducting zone based on a first semiconducting material comprising a region that will form a transistor channel region,
• form sacrificial regions on each side of the semiconducting zone, the sacrificial regions being based on a second semiconducting material and being configured so as to induce a strain in the semiconducting zone, then,
• in this order:
• remove the sacrificial gate block;
• replace the sacrificial gate block by a replacement gate block between the insulating spacers;
• remove the sacrificial regions;
• replace the sacrificial regions by replacement regions located on each side of the semiconducting zone, the replacement regions being based on a third semiconducting material different from the second semiconducting material.