VDMOS (Vertical Double-Diffusion Metal-Oxide-Semiconductor) device with non-uniform floating island structure

Abstract

A VDMOS (Vertical Double-Diffusion Metal-Oxide-Semiconductor) device with a non-uniform floating island structure belongs to the technical field of semiconductor power. For the VDMOS device, the non-uniform floating island structure is drawn into a first conductive type semiconductor drift region of a common VDMOS and comprises at least two layers of second conductive type semiconductor floating islands which are respectively an upper layer of second conductive type semiconductor floating island and a lower layer of second conductive type semiconductor floating island, wherein the upper layer of second conductive type semiconductor floating island is larger in transverse width dimension and lower in doping density, and the lower layer of second conductive type semiconductor floating island is smaller in transverse width dimension and higher in doping density. Compared with the common VDMOS, the VDMOS with the non-uniform floating island, provided by the invention, can adopt higher electrical resistivity of an epitaxial layer under the condition the same puncture voltage, thereby the on-resistance is greatly reduced; compared with a VDMOS with a uniform floating island, the VDMOS with the non-uniform floating island is wider in current path and also can lead the on-resistance to be reduced; and compared with a super-junction VDMOS, the VDMOS is better in the reverse recovery characteristic of a body diode and is relatively simple in process.

Description

technical field [0001] The invention belongs to the technical field of power semiconductor devices, and relates to a vertical double diffusion metal-oxide-semiconductor field effect transistor (Vertical Double Diffusion MOSFET, VDMOS), especially a VDMOS device with a floating island structure. Background technique [0002] VDMOS devices have many advantages such as high input impedance, fast switching speed, voltage drive, and good thermal stability, so they are widely used in power systems. In switching device applications, it is generally desired that VDMOS not only have a high breakdown voltage, but also have a low on-resistance to reduce power consumption, and at the same time have good body diode reverse recovery characteristics to suppress noise and voltage surges during switching . Due to the constraint relationship between on-resistance and breakdown voltage in traditional VDMOS (on-resistance is proportional to the 2.5th power of breakdown voltage), researchers ha...

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Problems solved by technology

Due to the constraint relationship between on-resistance and breakdown voltage in traditional VDMOS (on-resistance is proportional to the 2.5th power of breakdown voltage), researchers have proposed to introduce a super-junction structure (super-junction) into the drift region of ordinary VDMOS devices to Optimizing the trade-off between on-resistance and breakdown voltage (eg figure 1 shown), but because the super junction structure has two major disadvantages: poor reverse recovery characteristics of the body diode and high manufacturing process difficulty, the application of VDMOS devices with super junction structure is limited and the cost remains high

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