Trenched mosfets with embedded schottky in the same cell

Abstract

A semiconductor power device includes trenched semiconductor power device comprising a trenched gate surrounded by a source region encompassed in a body region above a drain region disposed on a bottom surface of a substrate. The semiconductor power device further includes an insulation layer covering the trenched semiconductor power device with a source-body contact trench opened therethrough the source and body regions and extending into an epitaxial layer below the body regions and filled with contact metal plug therein. The semiconductor power device further includes an embedded Schottky diode disposed near a bottom of the source-body contact trench below the contact metal plug wherein the Schottky diode further includes a Schottky barrier layer having a barrier height for reducing a leakage current through the embedded Schottky diode during a reverse bias between the drain and the source.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates generally to the cell structure, device configuration and fabrication process of power semiconductor devices. More particularly, this invention relates to a novel and improved cell configuration and processes to manufacture MOSFET device with embedded Schottky diodes in the same cell such that integrated cells with spacing savings and lower capacitance and higher performance are achieved.[0003]2. Description of the Related Art[0004]Conventional technologies for high efficiency DC / DC applications, a Schottky diode is usually added externally in parallel to a semiconductor power device, e.g., a power MOSFET device. FIG. 1A is a circuit diagram that illustrates the implementation of a Schottky with a power MOSFET device. The Schottky diode (SKY) is connected in parallel to the MOSFET device with a parasitic PN body diode to function as a clamping diode to prevent the body diode from turning on. In or...

AI Technical Summary

Benefits of technology

[0009]It is therefore an aspect of the present invention to provide new and improved semiconductor power device configuration and manufacture processes for providing semiconductor power devices with embedded Schottky diode such that space occupied by separate Schottky diodes can be saved and one of the major technical limitations discussed above can be overcome.

[0010]Another aspect of the present invention is to provide new and improved semiconductor power device configuration and manufacture processes for providing semiconductor power devices with embedded Schottky diode in the same cell such that parasitic capacitance can be reduced and device performance can be improved.

[0011]Another aspect of the present invention is to provide new and improved semiconductor power device configuration and manufacture processes for providing semiconductor power devices with embedded Schottky diode in the same cell wherein the manufacturing processes can be simplified with reduced number of masks required such that the production costs can be reduced and reliability of the products can be enhanced.

[0012]Another aspect of the present invention is to provide new and improved semiconductor power device configuration and manufacture processes for providing semiconductor power devices with embedded Schottky diode in the same cell wherein a dopant regions is provided at the bottom of a contact trench below the Schottky layer to reduce the forward voltage of the Schottky diodes such that improved device performance is achieved.

[0013]Another aspect of the present invention is to provide new and improved semiconductor power device configuration and manufacture processes for providing semiconductor power devices with embedded Schottky diode in the same cell wherein a dopant regions is provided at the bottom of a contact trench below the Schottky layer to reduce the ldsx is reduced and device performance improvements are achieved.

Problems solved by technology

The configuration as disclosed in the patented invention has a disadvantage that the Schottky diodes occupy additional space that is about the same space as the MOSFET.

The trench Schottky diodes further suffer from a high leakage between the drain and source due to the increase in the phosphorus dopant concentration in the channel region during the sacrificial and gate oxidation processes.

Also, the formation process requires additional contact mask for the Schottky diode thus increases the cost and processes complications for producing the MOSFET power device with Schottky diode.

Again, the configuration has the same disadvantage that the Schottky diodes occupy additional space thus limiting the further miniaturization of the device.

Furthermore, the manufacturing cost is increased due to the requirement that an additional P+ mask is required to form the Schottky diodes.

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