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 containing 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 tempering or bending thermal treatment, and wherein said transparent substrate has i) a second coating containing dielectric material, which includes a barrier layer for the diffusion of oxygen selected from the group consisting of Si.sub.3 N.sub.4 and silicon oxynitride, and ii) wherein said at least one metallic layer having properties in the infrared range is directly in contact with an underlying dielectric coating, said underlying dielectric coating containing zinc oxide in contact with said layers having infrared properties.