A vdmos device structure with self-shutoff capability and its preparation method

Abstract

The invention belongs to the field of discrete device design, and relates to a VDMOS device structure with self-shutoff capability and a preparation method thereof. The device structure includes a P ⁺ type substrate, the P ⁺ A P-type epitaxial layer is arranged on the P-type substrate, an N-type body region is arranged on the P-type epitaxial layer, and a P-type body region is arranged on the N-type body region. ⁺ type source region, in the formed VDMOS device structure, the peripheral metal field plate is connected with the metal part of the chip cell; the process of the present invention is simple and easy, and the implementation degree is high, and the new VDMOS structure is clear and simple, stable and reliable, and solves the problem of The reliability risk of floating gates of traditional VDMOS devices can improve the reliability of devices and has high industrial application value.

Description

technical field [0001] The invention belongs to the field of discrete device design, and relates to a VDMOS device structure with self-shutoff capability and a preparation method thereof. Background technique [0002] VDMOS devices are widely used in power management modules, DC-DC converters and other fields. In the application process, the front stage of the traditional structure VDMOS device is the driver input signal, because the front stage driver circuit and the traditional structure VDMOS device use different power supplies for power supply. , so it is very likely that the front-end driver will be powered off. In a VDMOS device, the current I between the drain and the source DS and the voltage between the gate and source V GS The relationship between them is as follows: [0003] [0004] Among them, V TH Indicates the turn-on voltage, C OX is the characteristic capacitance of the oxide layer of the VDMOS device, μ represents the permeability coefficient, W is t...

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Problems solved by technology

[0004] Among them, V TH Indicates the turn-on voltage, C OX is the characteristic capacitance of the oxide layer of the VDMOS device, μ represents the permeability coefficient, W is the width of the depletion layer of the VDMOS device, and L is the effective length of the conductive channel of the VDMOS device; The gate of the device is a floating potential, when the floating potential is very high, that is, V GS If it is too large, there will be a large current between the source and the drain, and this current will be poured into the subsequent load, which will cause irreversible damage to the latter load

[0005] When the above situation occurs, the output signal of the front-stage driver (that is, the gate input signal of the VDMOS device) will appear in a floating potential state. The phenomenon of turning on, and VDMOS is used as a power supply device in the power management module, DC-DC converter and other fields, the current passing through it is relatively large, and the VDMOS tube that is turned on for a long time will pour a large current into the subsequent load module, causing irreversible damage

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