A kind of ldmos device with stepped trench

Abstract

The present invention provides an LDMOS device with a stepped trench, comprising a first conductivity type semiconductor substrate, a first conductivity type semiconductor body region, a second conductivity type semiconductor drift region, a second conductivity type semiconductor source region, a highly doped The first conductivity type semiconductor body contact region, the gate structure, the gate structure includes a polysilicon gate electrode and a gate oxide layer, the inner upper surface of the second conductivity type semiconductor drift region also has a stepped trench, the bottom of the step and the second conductivity type The distance from the upper surface of the semiconductor drift region decreases gradually along the direction from the source region of the second conductivity type semiconductor to the drain region of the second conductivity type semiconductor, and polysilicon is filled in the stepped groove. The vertical electric field distribution in the 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 an LDMOS device with stepped trenches. 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. Conventional L...

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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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