Vertical double-diffused transistor and manufacturing method thereof

Abstract

The invention relates to the technical field of semiconductors, and provides a vertical double-diffused transistor and a manufacturing method thereof. A formed VDMOS device is of an axial symmetry structure with the central axis of a first trench as the axis of symmetry; the VDMOS device forms metal contact in a drain region through the first trench penetrating to the upper surface of a first buried layer so as to lead out a drain electrode; and the led-out drain electrode is positioned on the top surface, far away from the substrate, of the high-voltage VDMOS device. Therefore, the VDMOS device can be integrated in a BCD process, driving capability with low on resistance and high current is realized, the drain electrode does not need to be led out from the bottom of a device structure, and the integration density of the device is improved. Meanwhile, at least two buried layer structures in longitudinal gradient distribution are used for replacing a drift region to form a PN junction with a body region, and the PN junction is close to a parallel plane junction by utilizing a drain electrode communicating to an injection region in the first buried layer when the device is reverselybroken down, so the withstand voltage of the VDMOS device is effectively improved.

Description

technical field [0001] The present disclosure relates to the technical field of semiconductors, in particular to a vertical double-diffusion transistor and a manufacturing method thereof. Background technique [0002] The BCD (Bipolar-CMOS-DMOS) process manufactures bipolar devices and CMOS devices on the same chip at the same time. It combines the advantages of high transconductance and strong load driving capability of bipolar devices with high integration and low power consumption of CMOS, so that they learn from each other and give full play to their respective advantages. The integrated BCD process of Bipolar / CMOS / DMOS is used to combine three different process types: bipolar is for analog control; CMOS is for digital control; DMOS is for processing high voltage and high current in chip or system management. Realize the soft start and power output of the system. Since the BCD process combines the respective advantages of the above three devices, BCD-based products can...

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Problems solved by technology

[0007] In the manufacturing process of the VDMOS device 100, an isolation photolithography plate needs to be added for high-energy injection, and the drain of the VDMOS device, that is, the N-type buried layer 102, is drawn out. However, with the increase of the device withstand voltage specification, the N The thickness of the N-type epitaxial layer 103 will also increase accordingly, so it will be difficult to lead out the N-type buried layer 102 by high-energy implantation. At the same time, the increase in the thickness of the N-type epitaxial layer 103 will also lead to a larger isolation resistance, so that the molded device will have no on-resistance. The advantages

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