Power device substrate back surface processing method and power device preparation method

The invention relates to the technical field of semiconductor chips, in particular to a power device substrate back surface processing method and a power device preparation method. The method comprises the following steps: thinning the back surface of a substrate; forming a metal layer on the back surface of the substrate; and depositing and forming a tungsten structure layer on the metal layer. According to the substrate back surface processing method, tungsten with strong covering power is deposited on the back surface of the substrate, so that the uneven structure of the back surface of thesubstrate is effectively improved, and packaging and patching of a power device are facilitated; moreover, the tungsten material has the characteristics of excellent conductivity, stable chemical property, high heat resistance and small expansion coefficient, the oxidation risk of the substrate can be reduced while the basic conductive function is realized, the substrate structure is not easy todeform, and the packaging