Full-vertical type Si-based GaN UMOSFET power device and preparation method thereof

Abstract

The invention discloses a full-vertical type Si-based GaN UMOSFET power device and a preparation method thereof. The full-vertical type Si-based GaN UMOSFET power device comprises a silicon substrateand a metal oxide semiconductor field effect transistor structure which is mainly composed of an N+ source region layer, an N-drift layer and a P + channel layer. The N + source region layer, the N-drift layer and the P + channel layer are sequentially stacked on the silicon substrate in the direction gradually away from the silicon substrate. The silicon substrate is electrically connected with the N + source region layer and the drain electrode, the P + channel layer is electrically matched with the source electrode, and groove-shaped structures matched with the grid electrode are distributed in the P + channel layer and the N-drift layer. The sapphire substrate of the epitaxial structure is removed through an electrochemical method or a laser lift-off method, a device is manufactured onthe GaN epitaxial structure on the Si substrate subjected to flip-chip bonding, and the full-vertical type Si-based GaN UMOSFET is achieved. According to the full-vertical Si-based GaN UMOSFET provided by the invention, the high critical electric field and high mobility of the GaN material are fully utilized, the preparation cost of the device is reduced, and the industrialization of the device is facilitated.

Description

technical field [0001] The invention relates to a UMOSFET power device, in particular to an all-vertical Si-based GaN UMOSFET power device and a preparation method thereof, belonging to the technical field of semiconductors. Background technique [0002] Power devices refer to devices used to control and convert electrical energy. The devices are required to have the characteristics of high power, high frequency, high operating temperature and small size, so as to improve energy conversion efficiency. The third-generation semiconductor GaN material has a large band gap, high critical electric field and strong radiation resistance, and has become an ideal material for preparing power devices. GaN UMOSFET refers to a three-terminal enhancement device made of GaN material for controlling current on or off, and is an important part of power devices. In terms of classification structure, GaN power devices mainly include two types: horizontal and vertical structures. The most mat...

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Problems solved by technology

However, there are some unavoidable problems in the horizontal structure: the current collapse phenomenon in which the output power of the device under the RF signal is significantly lower than the power calculated under the DC condition; the breakdown voltage is limited by the lateral size, and the packaging density under the same performance is small; HEMT The middle 2DEG makes the device normally open, and the device is damaged during the groove and fluorine ion implantation to form a normally closed process.

For example, the current GaN UMOSFET prepared on sapphire is difficult to achieve a fully vertical structure due to the insulation of the buffer layer, so most of them are quasi-vertical structures, that is, the source and drain are on the same side. The phenomenon of current crowding cannot give full play to the advantages of high breakdown and high current of vertical devices

For another example, currently GaN full vertical devices are mainly completed on GaN self-supporting substrates. Homoepitaxy ensures a large breakdown voltage and high forward current density of the device, but due to the high cost and small size of the self-supporting substrate, The cost of GaN substrates and epitaxy is 50 to 100 times that of Si substrates, making it difficult to commercialize devices

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