Manufacturing method of extra-high voltage VDMOS field effect transistor

Abstract

The invention discloses a manufacturing method of an extra-high voltage VDMOS field effect transistor. The manufacturing method of an N<->type VDMOS comprises the following steps of: 1, adopting an N<->type substrate sheet; 2, manufacturing an N<->type VDMOS front structure on the front surface of the substrate sheet according to a conventional manufacturing process, wherein the N<->type VDMOS front structure comprises field oxide, a gate oxide layer, a polycrystalline silicon region, P<->Body, an N<+> source electrode, a P<+> contact region, an interlayer dielectric and front metal; 3, entering a thinning procedure, and carrying out thinning on the back surface of the N<->type substrate sheet to a required thickness; 4, N type impurities are injected into the back surface of the N<->typesubstrate sheet, so that impurity concentration at the back of the N<->type substrate sheet is increased and a thin N<+> layer is formed on the surface of the N<->type substrate sheet; and 5, enteringa back surface metallization process, and depositing metal on the back surface of the N<+> layer to form a drain electrode of the VDMOS. A front structure of a device is directly manufactured on thesubstrate sheet, the drain electrode of the VDMOS is formed through back thinning and back injection, epitaxial growth is omitted, and reduction of reliability of a VDMOS product due to increase of epitaxial defects caused by too thick epitaxial growth is avoided.

Description

technical field [0001] The invention relates to a semiconductor power device, in particular to a manufacturing method for realizing an ultra-high voltage VDMOS field effect transistor by using back thinning and back injection technology. Background technique [0002] The existing VDMOS technology usually grows epitaxy on the substrate, and then manufactures devices on the epitaxy. After the front process of the device is completed, the back is thinned and the back is metallized, and finally the VDMOS device is formed. Next, an N-type VDMOS is taken as an example to describe the manufacturing process of the existing VDMOS technology. [0003] The longitudinal section of the existing N-type VDMOS is as follows figure 1 As shown, its manufacturing method is as follows. The manufacture of N-type VDMOS starts from the N+ substrate material, the resistivity of the N+ substrate material is usually 0.001-0.1mΩ, and the thickness is 400-800um. Then grow N- epitaxy on the N+ substr...

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Problems solved by technology

[0007] The purpose of the present invention is to solve the problem that the existing VDMOS manufacturing method by growing epitaxy on the substrate is not suitable for the production of VDMOS above 1000V, and the thickening of the epitaxy will increase the number of defects such as slip lines and particles in the growing epitaxy

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