Manufacturing method for cilicon epitaxial wafer for 6'' VDMOS tube

The present invention relates to a preparation method of silicon epitaxial wafer for power VDMOS tube. Firstly, selection and usage of substrate are important, the selected substrate not only can meet the requirements for device, but also can meet the requirements for epitaxy. Its preparation method includes the following steps: selecting proper gas corrosion flow and gas corrosion time, reducing concentration of gas corrosion impurity in epitaxial reactor so as to reduce self-doping in epitaxial growth process; first layer epitaxial growth, on the substrate surface with high concentration utilizing lower temperature to grow a layer of purity epitaxial layer, encapsulating substrate surface and edge, controlling its growth temperature, growth rate and epitaxial time so as to make encapsulating layer obtain ideal effect, at the same time, selecting proper epitaxial condition to make the deformation of epitaxial wafer be minimum; and second layer epitaxial growth, utilizing tower temperature to grow a layer of epitaxial layer whose resistivity and thickness can meet requirements for device.