Mesa diode with low leakage and high withstand voltage terminal structure and preparation method thereof

Abstract

The invention provides a mesa diode with a low leakage and high withstand voltage terminal structure and a preparation method thereof. The mesa diode includes a back substrate, an N-type epitaxial layer, a P+ type layer in an anode active region, and a composite passivation layer on the diode mesa. layer, the composite passivation layer includes a silicon dioxide layer, a polysilicon layer and a silicon nitride layer, the preparation method steps of the present invention are as follows: 1, prepare a common mesa diode; 2, grow a layer of dioxide on the upper surface of the diode Silicon; 3. Deposit polysilicon on the silicon dioxide layer, and carry out phosphorus expansion treatment to form a polysilicon layer; 4. Deposit silicon nitride on the polysilicon layer to form a silicon nitride layer; 5. In the silicon nitride layer and The polysilicon layer is etched to obtain the silicon nitride layer and the polysilicon layer of the set pattern; 6, adopt an etching process to etch the exposed silicon dioxide layer to obtain the silicon dioxide layer of the set pattern; the present invention can improve The performance of the device and the realization of the process are simple.

Description

technical field [0001] The invention relates to the technical field of power semiconductor devices, in particular to a mesa diode with a low leakage and high withstand voltage terminal structure and a preparation method thereof. Background technique [0002] The performance and stability of semiconductor devices are closely related to the properties of semiconductor surfaces. In order to avoid the influence of ambient atmosphere and other external factors on the performance of semiconductor devices, it is necessary to add terminal structures around the devices. The terminal protection of the semiconductor surface can reduce various charges on the device surface, enhance the device's ability to block external ion contamination, control and stabilize the electrical characteristics of the semiconductor surface, protect the device, and prevent the device from mechanical and chemical damage. [0003] Termination and passivation protection are especially required for mesa-structu...

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Problems solved by technology

[0004] The most commonly used terminal structure of mesa diodes is protected by a passivation layer such as silicon dioxide, but the silicon dioxide film is a porous structure, so it has its inherent disadvantages, that is, it lacks resistance to the migration of alkali metal ions and prevents water vapor or other impurities. (such as aluminum, oxygen, etc.) the ability to penetrate, often make the performance of the device or circuit deteriorate or even fail

Another common passivation layer is silicon nitride. The advantage of silicon nitride is that it has high chemical stability, corrosion resistance and strong blocking effect of impurity ions such as sodium ions, but the interface stress between silicon nitride and silicon is large. , causing deformation of the silicon wafer

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