Laterally diffused MOS device

Abstract

The invention provides a laterally diffused MOS device. The device comprises a first conductive type semiconductor substrate, a first conductive type semiconductor body region, a second conductive type semiconductor drift region, a second conductive type semiconductor source region, a highly-doped first conductive type semiconductor body contact region, a gate structure, wherein the gate structurecomprises a polysilicon gate electrode and a gate oxide layer; at least two polysilicon islands are arranged on the upper surface of the interior of the second conductive type semiconductor drift region, and uniformly-distributed charges are stored in the polysilicon islands; and the distance from the bottom of the polysilicon islands to the first conductive type semiconductor substrate is increased gradually in the direction from the first conductive type semiconductor body region to a second conductive type semiconductor drain region. By setting the multiple polysilicon islands of differentdepths and for storing charges in the drift region, and by changing the charge quantity and the width of the drift region needing to be depleted, the electric field distribution in the drift region is more uniform, and the reverse blocking voltage of the device is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductor devices, in particular to a lateral double-diffusion MOS device. Background technique [0002] Metal oxide power MOS semiconductor devices, with the rapid development of the semiconductor industry, power electronics technology represented by high-power semiconductor devices has developed rapidly, and its application fields have continued to expand, such as the control of AC motors and printer drive circuits. Among various power devices today, laterally diffused MOS devices (LDMOS) have the advantages of high operating voltage and easy integration, so they are widely used. [0003] In the design of LDMOS devices, the breakdown voltage and on-resistance have always been the main goals that people pay attention to when designing such devices. The thickness of the epitaxial layer, doping concentration, and the length of the drift region are the most important parameters of LDMOS. The traditiona...

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Problems solved by technology

However, due to the substrate-assisted depletion effect, the effects of RESURF technology and super-junction LDMOS are greatly affected.

The reason is that the potentials at different positions in the drift region are different, so the degree of depletion by the substrate is different. If the drift region adopts a uniform thickness, the optimization of the electric field in the drift region cannot be achieved.

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