LDMOS transistor and preparation method thereof

Abstract

The invention provides an LDMOS (Laterally Diffused Metal Oxide Semiconductor) transistor and a preparation method thereof. The transistor comprises a semiconductor substrate in which a doping region of a first doping type is formed, and a well region of the first doping type and a well region of a second doping type which are opposite in doping type are formed in the doping region of the first doping type; a source region is positioned in the well region of the second doping type; the drain region is positioned in the well region of the first doping type; an STI structure is located between the source region and the drain region, the STI structure comprises a laminated structure formed in the shallow trench, and the laminated structure comprises insulating material layers and ferroelectric material layers which are alternately laminated; a grid electrode is located on the semiconductor substrate, one side of the grid electrode extends to the upper part of the source region, and the other side of the grid electrode extends to the upper part of the STI structure; a contact hole is connected with the grid electrode and the insulating material layer on the uppermost layer of the laminated structure; a metal layer is electrically connected with the contact hole. According to the LDMOS transistor, the breakdown voltage BV of an LDMOS transistor device is improved, and meanwhile the on-resistance Ron of the LDMOS transistor device is effectively reduced.

Description

technical field [0001] The invention relates to the field of double diffused metal oxide semiconductor (DMOS), in particular to an LDMOS transistor and a preparation method thereof. Background technique [0002] In power device applications, since DMOS (double-diffused metal-oxide-semiconductor) technology adopts a vertical device structure (such as a vertical NPN bipolar transistor), it has many advantages, including high current drive capability, low on-resistance Ron and high Breakdown voltage BV etc. There are two main types of DMOS transistors, vertical double diffused metal oxide semiconductor field effect transistor VDMOS and lateral double diffused metal oxide semiconductor field effect transistor LDMOS. Compared with common field effect transistors, LDMOS transistors have obvious advantages in terms of key device characteristics, such as gain, linearity, switching performance, heat dissipation performance, and reduction of stages. At the same time, LDMOS transistor...

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Problems solved by technology

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide an LDMOS transistor and a preparation method thereof, which are used to solve the problem that the LDMOS transistor device in the prior art adopts an STI structure in the drift region to increase the breakdown voltage. Bringing problems such as the contradiction between high breakdown voltage and low on-resistance performance requirements of LDMOS transistor devices

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