Integrated trench mosfet and junction barrier schottky rectifier with trench contact structures

Abstract

A trench MOSFET in parallel with trench junction barrier Schottky rectifier with trench contact structures is formed in single chip. The present invention solves the drawback brought by some prior arts, for example, the large area occupied by planar contact structure and high gate-source capacitance. As the electronic devices become more miniaturized, the trench contact structures of this invention are able to be shrunk to achieve low specific on-resistance of Trench MOSFET, and low Vf and reverse leakage current of the Schottky Rectifier.

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 an improved cell configuration and processes to manufacture trench MOSFET device with junction barrier Schottky rectifier in the same cell so that integrated cells with spacing savings and lower capacitance and higher performance are achieved.[0003]2. The Prior Arts[0004]Normally for high efficiency DC / DC application, a Schottky rectifier is externally added in parallel with a MOSFET device. FIG. 1 is a circuit diagram that illustrates the implementation of a Schottky diode with a power MOSFET device. Once the parasitic P / N diode is turned on, both the electron and hole carriers are generated thus require longer time to eliminate the carriers by electron-hole combination. In order to achieve higher speed and efficiency, the Schottky diode (SKY) ...

AI Technical Summary

Benefits of technology

The present invention provides improved semiconductor power devices with a trench junction barrier Schottky rectifier in single chip. The invention solves the technical problem of reducing space occupancy and cost-down of production compared to prior art. The devices have low specific on-resistance for trench MOSFET and low Vf and reverse leakage current for trench junction barrier Schottky rectifier. The invention also includes an insulation layer covering the trenched semiconductor power device with a source-body contact trench opened through and extending into the source and body regions and filled with Tungsten plugs therein. The heavily doped region at the bottom of each contact filled with a layer of Ti silicide / TiN or Co silicide / TiN along each trench contact sidewall and Tungsten plug connected to said source metal serves as anode of said Schottky rectifier. The structure disclosed in the patent text allows for improved performance and cost-effectiveness of semiconductor power devices.

Problems solved by technology

The configurations as disclosed in the patented invention have a disadvantage that the Schottky diodes occupy additional space for planar contact that is about the same space as the MOSFET.

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

The configuration again has disadvantages that the Schottky diode occupies additional space for planar contact and reverse leakage current Ir between anode and cathode is high.

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.

The configuration has disadvantage that it is difficult to optimize both performance of the Schottky diode and the trench MOSFET when they share same mesa space between two adjacent trenches and same source trench contact.

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

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