A kind of Schottky diode and its preparation method

Abstract

The invention provides a Schottky diode which comprises a substrate layer as well as a series of III-family nitride layers formed above the substrate layer, a metal field plate connected with the anode electrode and at least one P-type doped III-family nitride reinforcement layer which is filled between the metal field plate and a III-family nitride layer at the uppermost layer. Two-dimensional electron gas channels are formed between the adjacent III-family nitride layers by utilizing a heterogeneous structure; the III-family nitride layers and a cathode electrode are in ohmic contact; and the III-family nitride layers and an anode electrode are in Schottky contact. According to the Schottky diode provided by the inventio, the reverse withstand voltage capability and the forward withstand voltage capability are improved at the same time.

Description

technical field [0001] The invention relates to a Schottky diode and a preparation method thereof, belonging to the technical field of semiconductors. Background technique [0002] Diodes are widely used in power circuits. The ideal diode expected by a typical power circuit should include the following characteristics: First, when the device is in a reverse bias state (the cathode voltage is much higher than the anode voltage), the diode needs to be able to bear as much as possible High voltage, its withstand voltage depends on the performance requirements of the circuit for the device. In many high-voltage power switching applications, the diode is required to bear the back voltage of 600V or 1200V; second, when the device is in the forward biased state, it needs its The forward conduction voltage should be as low as possible to reduce the conduction loss, that is, a sufficiently low forward conduction resistance is required; third, the charge stored in the diode should be ...

AI Technical Summary

Problems solved by technology

[0006]First, in the Schottky diode disclosed in this document, the high barrier region 114 is recessed and formed on the top surface of the AlGaN layer. In the actual manufacturing process , the heterojunction of GaN and AlGaN needs to be formed by epitaxial growth first, and then a downwardly recessed opening needs to be defined on the top surface of the formed AlGaN to inject materials with higher band gap energy, thereby forming a high In the barrier region 114, in this process, due to the need to define openings in advance (generally by digging out a part of AlGaN), not only the process is complicated, but also after injecting materials with higher bandgap energy into the openings, it is easy to contact between the two. More defects are formed in the parts, which affects the improvement of the final withstand voltage capability of the Schottky diode, and thus limits the improvement of its reverse withstand voltage capability;

[0007]Second, in the Schottky diode disclosed in this document, the high potential barrier region is composed of AlGaN layer, and Mg, Cd are implanted in the AlGaN layer , Zn, Ca, N, O, C or a silicon dioxide layer to modify the AlGaN layer to form a high barrier region. In this process, the inventors only pay attention to planting Whether the implanted element layer helps to form a high-bandgap energy or a high-resistivity high barrier region, regardless of whether the implanted element helps to improve the forward conduction capability of the Schottky diode. In fact, according to the above It is recorded that when the implanted elements are N, O, C or even an inert gas, it cannot play a good role in improving the forward conduction capability of the Schottky diode, so that it is difficult for the Schottky diode disclosed in this document to simultaneously Ensure good withstand voltage and conduction capability, which in turn affects its application in the integration of power devices

Therefore, it is difficult for those skilled in the art to obtain the technical enlightenment of using the P-AlGaN layer to improve the forward conduction capability and reverse withstand voltage capability of Schottky diodes from this document

[0009] To sum up, there is a lack of a Schottky diode that can simultaneously improve forward conduction capability and reverse withstand voltage capability in the prior art

Images