CN202721133U

CN202721133U - Power diode device

Info

Publication number: CN202721133U
Application number: CN 201220395533
Authority: CN
Inventors: 朱廷刚
Original assignee: JIANGSU NENGHUA MICROELECTRONIC TECHNOLOGY DEVELOPMENT Co Ltd
Current assignee: JIANGSU NENGHUA MICROELECTRONIC TECHNOLOGY DEVELOPMENT Co Ltd
Priority date: 2012-08-10
Filing date: 2012-08-10
Publication date: 2013-02-06
Anticipated expiration: 2022-08-10

Abstract

The utility model discloses a power diode device. The device comprises a substrate, a buffer layer, an epitaxial layer, toroidal field plates and a metal layer forming a Schottky junction, wherein the substrate, the buffer layer, the epitaxial layer, the toroidal field plate and the metal layer are arranged in a stack-up state. One end of the epitaxial layer is provided with a plurality of guard rings, wherein the end is adjacent to the toroidal field plate. A plurality of the concave and convex portions which are in an annular shape are formed on the toroidal field plates. Peaks of convex portions of the toroidal field plates are gradually raised from an inner side to an outer side of a power part. Lowest points of the toroidal field plates are gradually raised from the inner side to the outer side of the power part. A projection of the toroidal field plate to the epitaxial layer is located in the guard ring which is closest to a center, wherein the toroidal field plate is closest to the center of the power diode device. The metal layer covers the concave portions of any toroidal field plate. The epitaxial layer is electrically connected with a cathode and the metal layer is connected with an anode.

Description

The power diode device

Technical field

The utility model relates to a kind of power diode device.

Background technology

The power diode device is wanted to bear high voltage, just must adopt advanced terminal structure design in the device architecture.Its structure as shown in Figure 1, the effect of this terminal structure is to weaken the electric field of electrode edge to strengthen spike, makes the Electric Field Distribution planarization, avoids the device premature breakdown.Therefore, in the design process of high power schottky device, after the doping content and thickness of having determined the voltage barrier layer, the design of the terminal structure of Schottky electrode periphery will determine that can device bear desired high voltage.

Field limiting ring (guard ring) is the most frequently used terminal structure of power diode device, and its preparation technology is very ripe for silicon-based devices, as shown in Figure 2, usually finishes by several operating procedures:

The N-/N+ epitaxial structure that has suitable doping content and thickness by the design growth;

Form mask by the semiconductor microactuator processing technology at device surface, carry out selectivity p type impurity Implantation;

Remove mask, through forming P type terminal structure behind the thermal annealing;

Adopt the semiconductor microactuator processing method to make anode and the negative electrode of Schottky diode.

Although the field limiting ring structure effect is fine and by wide-scale adoption in silica-based power electronic device,, this structure but can not be transplanted in the technological process of GaN power electronic device simply.Its chief reason is: carry out the P type by ion injection method and mix also immature in the GaN material; Specifically, when the Implantation that is accelerated is in the monocrystal material, energetic ion will greatly destroy the order of material lattice, and then form highdensity lattice defect in the material of injection region.In traditional silicon device technique, as long as just can remove the lattice damage that Implantation brings fully by thermal annealing (general temperature is about 1100 degree); But, because the special physical property of wide bandgap semiconductor GaN material only has and adopts the heat treatment that surpasses 1500 degree just might remove the lattice damage that Implantation brings.And the heat treatment of 1500 degree can make the GaN material breakdown of device surface, and Schottky barrier is reduced, and increases the reverse leakage current of Schottky electrode and reduces the oppositely withstand voltage of device; Simultaneously, the heat treatment more than 1500 degree is also very high to the requirement of annealing device, causes the device preparation cost significantly soaring.

In sum, traditional Implantation field limiting ring technique can not be indiscriminately imitated in preparation technology's flow process of power diode device simply.Therefore, how in the power diode device, to form the key technology that reliable P type field limiting ring terminal structure is preparation high power schottky device.

Summary of the invention

For the problems referred to above, main purpose of the present utility model provides a kind of power diode device and preparation method thereof, can effectively reduce the electric field strength of Schottky electrode periphery, improves the reverse voltage endurance capability of GaN schottky device.

In order to solve an above-mentioned difficult problem, the scheme that the utility model is taked is a kind of power diode device, it comprises the substrate of mutually stacked setting, resilient coating, epitaxial loayer, the annular field plate, form the metal level of schottky junction, described epitaxial loayer has a plurality of field limiting rings at its end adjacent with described annular field plate, be formed with a plurality of ringwise jogs on the described annular field plate, the peak of the protuberance of annular field plate raises laterally gradually from the inboard of this power component, the minimum point of annular field plate raises laterally gradually from the inboard of this power component, the projection that the annular field plate at the most close described power diode device center outwards prolongs layer is positioned at by paracentral field limiting ring, described metal level covers the recess of any annular field plate, described epitaxial loayer is electrically connected mutually with negative electrode, and described metal level links to each other with anode.

Preferably, described substrate is made by in sapphire, carborundum or silicon one or more.

Preferably, described resilient coating is made by in GaN, AlN one or more.

Preferably, described annular field plate is made by insulating material.

Preferably, the width between each recess of described annular field plate is 0.1-10 μ m.

Preferably, the minimum point of each recess of described annular field plate to the distance of the peak of protuberance is 0.01-1 μ m.

Preferably, the distance between adjacent two the protuberance peaks of described annular field plate is 0.01-10 μ m.

Preferably, any recess of described annular field plate is projected to coinciding with described field limiting ring of small part to epitaxial loayer.

Preferably, described epitaxial loayer comprises a GaN layer and the 2nd GaN layer of stacked setting, a described GaN layer is adjacent with resilient coating, described the 2nd GaN layer is adjacent with annular field plate, a described GaN layer is n++ type GaN, described the 2nd GaN layer is n-type GaN or i-GaN, and described field limiting ring is P-GaN.

The utility model adopts above structure and method, has the following advantages:

1, not only avoid Implantation and follow-up superhigh temperature annealing process, and combined P type GaN field limiting ring and two kinds of high voltage terminal structures of medium field plate, but the reverse voltage endurance capability of Effective Raise GaN schottky device.

, optimize the degree of depth of recess, the electric field that width and spacing can lower electrode edge greatly strengthens spike, and can make whole terminal structure dwindle area, thereby can produce more power diode device chip at the wafer of same area.

, plough groove type P-type extension GaN extra show board terminal structure can guarantee that schottky device bears the voltage that substantially exceeds designing requirement, thereby guarantee stability and the reliability of power diode device.

Description of drawings

Fig. 1 is the structure of traditional Schottky diode.

Fig. 2 a is the first step of the field limiting ring terminal structure forming process of conventional schottky.

Fig. 2 b is the second step of the field limiting ring terminal structure forming process of conventional schottky.

Fig. 2 c is the 3rd step of the field limiting ring terminal structure forming process of conventional schottky.

Fig. 2 d is the 4th step of the field limiting ring terminal structure forming process of conventional schottky.

Fig. 3 is the power diode device at the back side that is arranged on substrate of the negative electrode in the utility model.

Fig. 4 is the power diode device of the side that is arranged on substrate of the negative electrode in the utility model.

Fig. 5 a is through steps A among the power diode device preparation method in the utility model) after structural representation.

Fig. 5 b is the step B of the power diode device preparation method in the utility model) in form the structural representation of mask in epi-layer surface.

Fig. 5 c is the step B of the power diode device preparation method in the utility model) in form structural representation behind the cannelure.

Fig. 5 d is the step of the power diode device preparation method in the utility model

C) form the structural representation of field limiting ring in.

Fig. 5 e is through step D among the power diode device preparation method in the utility model) after structural representation.

Fig. 5 f is through step e among the power diode device preparation method in the utility model) after structural representation.

Fig. 5 g is through step F among the power diode device preparation method in the utility model) after structural representation.

Fig. 6 is the intensity distribution of 600V level GaN schottky diode device surface field under the reverse biased of emulation.

Fig. 7 a has shown the reverse I-V curve chart of GaN Schottky diode.

Fig. 7 b has shown the forward I-V curve chart of GaN Schottky diode.

In the accompanying drawing: 1, substrate; 2, epitaxial loayer; 21, a GaN layer; 22, the 2nd GaN layer; 3, field limiting ring; 4, negative electrode; 5, anode; 6, resilient coating; 7, protuberance; 8, recess; 9, annular field plate; 10, metal level; 11, mask.

Embodiment

Below in conjunction with Figure of description preferred embodiment of the present utility model is described in detail; thereby so that advantage of the present utility model and feature can be easier to be those skilled in the art will recognize that protection range of the present utility model is made more explicit defining.

Among the first embodiment of the present utility model: a kind of power diode device, it comprise mutually stacked setting substrate 1, resilient coating 6, epitaxial loayer 2, annular field plate 9, form the metal level 10 of schottky junction.

Epitaxial loayer 2 is electrically connected mutually with negative electrode 4, and metal level 10 links to each other with anode 5.

Shown in accompanying drawing 3 and 4, when substrate 1 was conductor, negative electrode 4 can be arranged on the back side of substrate 1.When substrate 1 was the bad material of insulator or conductivity, negative electrode 4 can be arranged on the side of a GaN layer 21.

Substrate 1 is made by in sapphire, carborundum or silicon one or more.

Resilient coating 6 is made by in GaN, AlN one or more.

Epitaxial loayer 2 is made by GaN.Epitaxial loayer 2 comprises a GaN layer 21 and the 2nd GaN layer 22 of stacked setting, a described GaN layer 21 is adjacent with resilient coating 6, described the 2nd GaN layer 22 is adjacent with annular field plate 9, a described GaN layer 21 is n++ type GaN, described the 2nd GaN layer 22 is n-type GaN or i-GaN, and negative electrode 4 is electrically connected mutually with a described GaN layer 21.

Epitaxial loayer 2 has a plurality of field limiting rings 3 at itself and described annular field plate 9 adjacent ends, and field limiting ring 3 is P-GaN.Analyze from material behavior, GaN is the material that is fit to very much prepare the novel high-performance power electronic device, and made device performance can surmount traditional silica-based power electronic device far away.GaN has breakdown electric field and the better heat-resisting ability that exceeds an order of magnitude than Si material.High breakdown electric field makes the GaN Schottky diode can replace Si PIN high-voltage diode.Be subjected to the impact of minority carrier storage effect in the PN junction district, the switching speed of PIN diode is slow more a lot of than Schottky diode again, and this Design and implementation to the efficient power system is very disadvantageous.Employing exactly can solve above contradiction based on the Schottky rectifier of wide bandgap semiconductor GaN.The GaN Schottky diode can adopt less thickness and the voltage barrier layer of high-dopant concentration more, thereby the series resistance of device can reduce greatly, makes high voltage applications become possibility.

Annular field plate 9 is made by insulating material.This kind dielectric can be silicon nitride SiNx, silicon oxide sio x etc.Be formed with a plurality of ringwise jogs 7 on the annular field plate 9, the peak of the protuberance 7 of annular field plate 9 raises laterally gradually from the inboard of this power component, the minimum point of annular field plate 9 raises laterally gradually from the inboard of this power component, the annular field plate 9 at the most close described power diode device center is positioned at by paracentral field limiting ring 3 to the projection of epitaxial loayer 2, and described metal level 10 covers the recess 8 of any annular field plate 9.Width between each recess 8 of annular field plate 9 is 0.1-10 μ m.The minimum point of each recess 8 of annular field plate 9 to the distance of the peak of protuberance 7 is 0.01-1 μ m.Distance between annular field plate 9 adjacent two protuberance 7 peaks is 0.01-10 μ m.Any recess 8 of annular field plate 9 is projected to coinciding with described field limiting ring 3 of small part to epitaxial loayer 2.

Preparation method among the first embodiment shown in accompanying drawing 5a-5g, it may further comprise the steps:

A) preparation substrate 1 and resilient coating 6, use metal organic source chemical gas-phase deposition system (MOCVD) epitaxial growth structure the one GaN layer 21 and the 2nd GaN on resilient coating 6, namely form n++ type GaN at the NH3 of early growth period doped with high concentration, behind the doping certain hour, the NH3 of the relative low concentration that mixes forms n-type GaN or i-GaN;

B) form mask 11 by the semiconductor microactuator processing technology at device surface, mask 11 is formed by dielectric, adopts dry etching method to offer a plurality of cannelures from 2 extension of mask 11 table facing epitaxy layers, and this cannelure is at least part of is positioned at epitaxial loayer 2;

C) use optionally epitaxial growth formation field limiting ring 3 in cannelure of metal organic source chemical gas-phase deposition system;

D) using plasma enhancing chemical gaseous phase depositing process covers dielectric and makes annular field plate 9;

E) covering metal layer 10 is made anode 5 to form schottky junction on annular field plate 9;

F) adopt the semiconductor microactuator processing method, epitaxial loayer 2 and negative electrode 4 are electrically connected mutually make anode 5.

Business software TCAD is simulated (see figure 6) to the device that the 600V level GaN Schottky diode of having optimized has plough groove type P-type extension GaN extra show board terminal structure; From the result of emulation, device is when pressure-bearing 600V, and near the maximum electric field intensity＜1.7MV/cm the Schottky electrode is significantly less than the critical breakdown electric field intensity (3MV/cm) of GaN material.Can find out thus, the plough groove type P-type extension GaN extra show board terminal structure of innovation can guarantee that schottky device bears the 600V voltage that substantially exceeds designing requirement, thereby has guaranteed stability and the reliability of power diode device.

The test result of device is shown in Fig. 7 a and Fig. 7 b: the GaN Schottky diode is when reverse withstand voltage 900V, and leakage current that is to say that less than 200 microamperes device electric breakdown strength will substantially exceed 900V; Simultaneously, during device forward conduction 8A, forward voltage drop is less than 2V.This result has proved that this terminal structure and technique can make the reverse withstand voltage theoretical prediction value that reaches of GaN Schottky diode.Terminal structure after the improvement can further improve the Unclamped Inductive Switching(UIS of device) ability, the use life cycle of significant prolongation device.

Above-described embodiment only is explanation technical conceive of the present utility model and characteristics, and its purpose is to allow the personage who is familiar with technique can understand content of the present utility model and according to this enforcement, can not limit protection range of the present utility model with this.All equivalences of doing according to the utility model Spirit Essence change or modify, and all should be encompassed within the protection range of the present utility model.

Claims

1. power diode device, it is characterized in that: it comprises the substrate of mutually stacked setting, resilient coating, epitaxial loayer, the annular field plate, form the metal level of schottky junction, described epitaxial loayer has a plurality of field limiting rings at its end adjacent with described annular field plate, be formed with a plurality of ringwise jogs on the described annular field plate, the peak of the protuberance of annular field plate raises laterally gradually from the inboard of this power component, the minimum point of annular field plate raises laterally gradually from the inboard of this power component, the projection that the annular field plate at the most close described power diode device center outwards prolongs layer is positioned at by paracentral field limiting ring, described metal level covers the recess of any annular field plate, described epitaxial loayer is electrically connected mutually with negative electrode, and described metal level links to each other with anode.

2. power diode device according to claim 1 is characterized in that: described substrate is made by in sapphire, carborundum or silicon one or more.

3. power diode device according to claim 1 is characterized in that: described resilient coating is made by in GaN, AlN one or more.

4. power diode device according to claim 1, it is characterized in that: described annular field plate is made by insulating material.

5. power diode device according to claim 1, it is characterized in that: the width between each recess of described annular field plate is 0.1-10 μ m.

6. power diode device according to claim 1, it is characterized in that: the minimum point of each recess of described annular field plate to the distance of the peak of protuberance is 0.01-1 μ m.

7. power diode device according to claim 1, it is characterized in that: the distance between adjacent two the protuberance peaks of described annular field plate is 0.01-10 μ m.

8. power diode device according to claim 1 is characterized in that: any recess of described annular field plate is projected to coinciding with described field limiting ring of small part to epitaxial loayer.

9. power diode device according to claim 1, it is characterized in that: described field limiting ring forms by epitaxial regrowth.

10. power diode device according to claim 1, it is characterized in that: described epitaxial loayer comprises a GaN layer and the 2nd GaN layer of stacked setting, a described GaN layer is adjacent with resilient coating, described the 2nd GaN layer is adjacent with annular field plate, a described GaN layer is n++ type GaN, described the 2nd GaN layer is n-type GaN or i-GaN, and described field limiting ring is P-GaN, and described negative electrode is electrically connected mutually with a described GaN layer.