CN202058741U

CN202058741U - Schottky diode with low positive conductive voltage drop

Info

Publication number: CN202058741U
Application number: CN2011200649447U
Authority: CN
Inventors: 童钧彦; 王凯莹; 吕佳玲; 吴国贤; 陈坤贤
Original assignee: JINGMAO S&T HOLDINGS CO Ltd
Current assignee: JINGMAO S&T HOLDINGS CO Ltd; Pynmax Tech Co Ltd
Priority date: 2011-03-14
Filing date: 2011-03-14
Publication date: 2011-11-30
Anticipated expiration: 2021-03-14

Abstract

The utility model provides a schottky diode with low positive conductive voltage drop. An N- type doping drifting layer is formed on an N+ type doping drifting layer and provided with a first surface, a protecting ring recessed to the first surface is formed, a P type doping area is arranged in the protecting ring, an oxide layer and a metal layer are further formed on the surface of the N- type doping drifting layer, and a schottky barrier is formed at the position of the metal layer contacting with the N- type doping drifting layer and the P type doping area. The schottky barrier is lower than the surface of the N- type doping drifting layer, so that the thickness of the N- doping drifting layer below the schottky barrier is decreased, and the positive conductive voltage drop of the schottky diode is further reduced.

Description

The Schottky diode of low forward conduction voltage drop

Technical field

The utility model is about a kind of Schottky diode, refers to a kind of Schottky diode of low forward conduction voltage drop especially.

Background technology

As shown in Figure 6, be the structural section of existing Schottky diode, mainly be on a N+ type doped layer 80, to be formed with a N-type doping drift layer 81, form a recessed retaining ring 82 on this N-type doping drift layer 81, and in retaining ring 82, form a P type doped region; N-type doping drift layer 81 surfaces further form an oxide layer 83 and a metal level 84 again, and the position that this metal level 84 contacts with N-type doping drift layer 81, P type doped region is to constitute a Schottky barrier 85; Moreover the bottom surface of aforementioned N+ type doped layer 80 is formed with a metal level, to constitute a bottom-side electrodes 86.

In previous constructions, because the energy of the free electron in the N-type doping drift layer 81 rank are low than the energy of the free electron in the metal level 84 rank, do not having under the situation of bias voltage, the electronics of N-type doping drift layer 81 can't transit in the metal level 84 on high energy rank by Schottky barrier 85, when applying forward bias voltage drop, free electron in the N-type doping drift layer 81 obtain energy and the metal level 84 that can transit to the high energy rank to produce electric current, owing to there is not the carrier of minority in the metal level 84, can't store charge, so the time of backward recovery is very short; Schottky diode is to utilize metal and semiconductor junction as Schottky barrier from the above, to produce the effect of rectification, different with the PN junction that produces by the semiconductor/semiconductor knot in the general diode, and the characteristic of utilizing Schottky barrier makes Schottky diode have lower conducting voltage to fall that (voltage of general PN junction diode is reduced to 0.7～1.7 volt, the voltage drop of Schottky diode then is 0.15～0.45 volt), and can improve the speed of switching.

Please refer to shown in Figure 7 again, it is the IV performance diagram of Schottky diode, its announcement has the relation of forward conduction voltage and reverse-breakdown voltage branch and electric current, by characteristic curve as can be seen: when electric current I more height, forward conduction voltage V also can follow and improve, and forward conduction voltage improves the characteristic and the application thereof that certainly will influence Schottky diode.And according to experimental result, there is a proportional relation in the N-type doping drift layer 81 thickness D of the forward conduction voltage of Schottky diode and its Schottky barrier 85 belows, N-type doping drift layer 81 thickness D are bigger, forward conduction voltage is bigger, otherwise, 81 thickness D are little for N-type doping drift layer, and then forward conduction voltage will reduce relatively.

Summary of the invention

Therefore the utility model main purpose is to provide the Schottky diode of a low forward conduction voltage drop, and it can reduce the forward conduction voltage drop of Schottky diode, and can not change reverse-breakdown voltage by changing the structure of Schottky diode.

For reaching the major technique means that aforementioned purpose takes is that aforementioned Schottky diode is comprised:

One N+ type doped layer;

One N-type doping drift layer is formed on the aforementioned N+ type doped layer, and this N-type doping drift layer has a first surface, and forms the retaining ring of a recessed first surface, is a P type doped region in the retaining ring;

One oxide layer is formed on the aforementioned N-type doping drift layer;

One metal level is to be formed on aforementioned oxide layer and the N-type doping drift layer, and this metal level constitutes a Schottky barrier with the position that N-type doping drift layer, P type doped region contact, and this Schottky barrier is to be positioned at below the first surface of N-type doping drift layer.

During enforcement, this N-type doping drift layer is at the inboard second surface that is lower than first surface that forms of retaining ring, and second surface does not comprise P type doped region.

During enforcement, this N-type doping drift layer forms a second surface that is lower than first surface in that retaining ring is inboard, and second surface 202 comprises the part of P type doped region.

Compared with prior art, the utility model utilizes the schottky barrier height of the Schottky diode of previous constructions to be lower than the first surface of N-type doping drift layer, dwindle the N-type doping drift layer thickness of Schottky barrier below by this, thereby can reduce the forward conduction voltage drop of Schottky diode.

Description of drawings

Fig. 1 is the structural representation of the utility model first preferred embodiment.

Fig. 2 is the partial structurtes schematic diagram of the utility model first preferred embodiment.

Fig. 3 is the partial structurtes schematic diagram of the utility model second preferred embodiment.

Fig. 4 is a structural representation of existing Schottky diode.

Fig. 5 is a performance diagram of the present utility model.

Fig. 6 is the another structural representation of existing Schottky diode.

Fig. 7 is the performance diagram of existing Schottky diode.

Embodiment

Below cooperate preferred embodiment graphic and of the present utility model, further setting forth the utility model is to reach the technological means that predetermined utility model purpose is taked.

About first preferred embodiment of the present utility model, please refer to shown in Figure 1, mainly be on a N+ type doped layer 10, to be formed with a N-type doping drift layer 20, this N-type doping drift layer 20 has a first surface 201, and being formed with a retaining ring 21 that is recessed in first surface 201, is a P type doped region in this retaining ring 21; The first surface 201 of N-type doping drift layer 20 further is formed with an oxide layer 30 again, and oxide layer 30 partly covers and contact the P type doped region in the retaining ring 21; Moreover, further forming a metal level 40 on N-type doping drift layer 20 and the oxide layer 30, this metal level 40 constitutes a Schottky barrier 41 with the position that N-type doping drift layer 20, P type doped region contact;

And principal character of the present utility model is to make this Schottky barrier 41 be positioned at the first surface of N-type doping drift layer 20 below 201, use N-type doping drift layer 20 thickness that dwindle Schottky barrier 41 belows, a kind of feasible pattern of finishing aforementioned structure is as described below:

Please refer to shown in Figure 3, before forming aforementioned metal layer 40, earlier N-type doping drift layer 20 is carried out etching in retaining ring 21 area inside, make N-type doping drift layer 20 be lower than the second surface 202 of first surface 201 in retaining ring 21 inboard formation one, meaning is a N-type doping drift layer 20 in the thickness d 1 at first surface 201 places greater than the thickness d 2 at second surface 202 places, then at first of N-type doping drift layer 20, second surface 201,202 and P type doped region, form this metal level 40 on the oxide layer 30, this metal level 40 and N-type doping drift layer 20 second surfaces 202, the position of P type doped region contact constitutes Schottky contacts, and will form Schottky barrier 41.In the present embodiment, carry out etched zone at the first surface 201 of N-type doping drift layer 20 and do not comprise P type doped region in the retaining ring 21 in retaining ring 21 inboards, just second surface 202 is too late in P type doped region, but based on the convenient purpose of implementing, also can be together with the part etching (as shown in Figure 2) downwards in the lump of P type doped region in the retaining ring 21, just second surface 202 comprises the part of P type doped region.

Although the utility model is N-type doping drift layer 20 thickness by reduction Schottky barrier 41 belows, to reduce forward conduction voltage drop, but still can guarantee that reverse-breakdown voltage is unaffected, please refer to the schematic construction of Fig. 4 for general Schottky diode, it is when backward recovery, N-type doping drift layer can form the electric field e of a similar P type doped region and Schottky barrier bottom profiled shape below P type doped region and Schottky barrier, after the utility model moves down the height of Schottky barrier, the bottom of aforementioned electrostatic field e also can be to moving down, based on the prerequisite of guaranteeing that reverse-breakdown voltage is constant, aforementioned N-type doping drift layer 20 first surfaces 201 downward etched depth are that to be no more than N+ type doped layer with its electric field e bottom be principle.

And for example shown in Figure 5, it is the utility model and the existing Schottky diode performance diagram obtained of experiment respectively, by characteristic curve as can be seen, under the condition of same electrical flow valuve, forward conduction voltage drop V1 of the present utility model is less than the forward conduction voltage drop V2 of existing Schottky diode.

The above only is preferred embodiment of the present utility model, be not that the utility model is done any pro forma restriction, though the utility model discloses as above with preferred embodiment, yet be not in order to limit the utility model, any those of ordinary skill in the art, in the scope that does not break away from technical solutions of the utility model, when the technology contents that can utilize above-mentioned announcement is made a little change or is modified to the equivalent embodiment of equivalent variations, in every case be the content that does not break away from technical solutions of the utility model, according to technical spirit of the present utility model to any simple modification that above embodiment did, equivalent variations and modification all still belong in the scope of technical solutions of the utility model.

Claims

1. the Schottky diode of a low forward conduction voltage drop is characterized in that, comprising:

One N+ type doped layer;

One N-type doping drift layer is formed on the described N+ type doped layer, and this N-type doping drift layer has a first surface, and forms the retaining ring of a recessed first surface, is a P type doped region in this retaining ring;

One oxide layer is formed on the described N-type doping drift layer;

One metal level is to be formed on described oxide layer and the N-type doping drift layer, and this metal level constitutes a Schottky barrier with the position that N-type doping drift layer, P type doped region contact, and this Schottky barrier is to be positioned at below the first surface of N-type doping drift layer.

2. according to the Schottky diode of the described low forward conduction voltage drop of claim 1, it is characterized in that this N-type doping drift layer forms a second surface that is lower than first surface in that retaining ring is inboard, and second surface does not comprise P type doped region.

3. according to the Schottky diode of the described low forward conduction voltage drop of claim 1, it is characterized in that this N-type doping drift layer forms a second surface that is lower than first surface in that retaining ring is inboard, and second surface (202) comprises the part of P type doped region.