A transparent substrate provided with a stack of thin layers having at least one metallic layer having properties in the infrared range and two coatings having a base of dielectric material located one under and the other over the layer having properties in the infrared range, as well as a protective metallic layer placed immediately over and in contact with the layer having properties in the infrared range, in order to prevent modification of properties of the stack when the substrate is submitted to a thermal treatment of the tempering or bending kind, and said transparent substrate has i) a second coating having a base of dielectric material, includes a barrier layer for the diffusion of oxygen selected from the group consisting of silicon oxides, nitrides and carbides of a thickness of at least 10 nanometers, and ii) a layer having properties in the infrared range is directly in contact with the underlying dielectric coating.