A kind of vertical conduction gan normally off type misfet device and its manufacturing method

Abstract

The invention relates to a longitudinal conduction GaN (gallium nitride) normally-off MISFET (metal-insulator-semiconductor field effect transistor) device and a manufacturing method of the MISFET device, wherein an epitaxial layer comprises a primary epitaxial growth n type light-doped GaN layer and a secondary epitaxial layer growing in a selection area of the light-doped GaN layer; the secondary epitaxial layer comprises a first impurity filtering layer, an electron blocking layer, a second impurity filtering layer, a non-doped epitaxial GaN layer and a heterostructure barrier layer from bottom to top; a groove channel is formed after secondary epitaxial growth; an insulating layer covers the surface of the groove channel and the surface of the heterostructure barrier layer; a grid electrode covers the groove channel on the insulating layer; two source electrode areas are respectively formed at two ends of the insulating layer by etching; two pieces of ohmic metal are respectively arranged at the source electrode areas by evaporation, so that source electrodes contacted with the heterostructure barrier layer can be formed; a piece of drain electrode ohmic contact metal is arranged at the back of a conductive GaN substrate. The MISFET device is simple in structure and high in process repeatability and reliability, and is capable of effectively inhibiting the diffusion of impurities in a secondary growth interface or the electron blocking layer, so that the electrical properties of 2DEG of the electron blocking layer and a heterostructure channel can be optimized.

Description

technical field [0001] The present invention relates to the technical field of semiconductor devices, and more specifically, to a GaN normally-off MISFET device with vertical conduction and a manufacturing method thereof. Background technique [0002] GaN semiconductor materials have superior properties such as large band gap, high breakdown electric field, large saturated electron drift velocity and high thermal conductivity, and there is a two-dimensional electron gas (2DEG) with high concentration and high electron mobility at the heterojunction interface. Compared with Si materials, it is more suitable for the preparation of power electronic devices with high power, large capacity and high switching speed, and becomes an ideal substitute for the next generation of power switching devices. [0003] GaN power switching devices are divided into lateral conduction devices and vertical conduction devices from the perspective of device structure. The lateral conduction device...

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Problems solved by technology

Selected area growth generally requires a patterned mask layer (commonly used such as SiO 2 ) to select the area to be grown, but this mask process will encounter the following problems: it is difficult to etch the mask layer when it is removed by etching, and there will be a large amount of impurities remaining on the secondary growth interface (such as Si ), in the secondary epitaxial growth, the residual impurity element is very easy to diffuse upward into the electron blocking layer under the high temperature growth environment, thereby compensating with the p-type doping element (commonly used such as Mg) of the electron blocking layer , which seriously deteriorates the quality of the electron blocking layer, resulting in a significant drop in device performance

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