Reduction in the annealing temperature of an IGZO layer obtained by sol gel

A method for forming on a substrate an active zone of metal oxide for an electronic device including:

• a) liquid phase deposition on the substrate of a first solution based on indium, zinc and an element X selected from Ga, Sb, Be, Al, Ni, then heat treatment in such a way as to form a first layer made of a first metal oxide of Ina1Xb1Znc1Od1, having a first atomic fraction of indium, a first atomic fraction of element X, a first atomic fraction of zinc, such that the first metal oxide is richer in indium and in element X than in zinc,
• b) liquid phase deposition on the first layer of a second solution based on indium, zinc and the element X, then heat treatment in such a way as to form a second layer made of a second metal oxide of Ina2Xb2Znc2Od2, having a second atomic fraction of indium, a second atomic fraction of element X, a second atomic fraction of zinc, such that the second metal oxide is richer in zinc than in element X, and richer in zinc than the first oxide while being less rich in element X than the first oxide,
• c) liquid phase deposition on the second layer of a third solution based on indium, zinc and the element X, then heat treatment in such a way as to form a third layer made of a third metal oxide of Ina3Xb3Znc3Od3, having a third atomic fraction of indium, a third atomic fraction of element X, a third atomic fraction of zinc, the third oxide being richer in element X than the second oxide while being less rich in element Zn than the second oxide.