CN204029813U - High pressure resistant plough groove type rectifying device - Google Patents

Abstract

The utility model discloses a kind of high pressure resistant plough groove type rectifying device, be positioned at the epitaxial loayer being provided with light dope first conduction type above described substrate layer, one gate groove is positioned at described groove, one conductive polycrystalline silicon body embeds in described gate groove, in the polysilicon middle and lower part of conductive polycrystalline silicon body middle and lower part in gate groove and and be provided with the first silicon dioxide oxide layer between epitaxial loayer, the polysilicon top being positioned at conductive polycrystalline silicon body top is positioned at metal level, and between polysilicon top surrounding and upper metal level, be provided with the second silicon dioxide oxide layer, ohmic contact face is formed between described polysilicon top upper surface and upper metal level, be positioned at described epitaxial loayer and have the second conduction type doped region at groove surrounding side surface, described in this, the second conduction type doped region and epitaxial loayer form pn junction interface.The utility model improves the reliability of device, and potential lines density reduces at the top of groove, reduce further the electric leakage of device.

Description

High pressure resistant plough groove type rectifying device

Technical field

The present invention relates to rectifying device, particularly the high pressure resistant plough groove type rectifying device of one.

Background technology

Rectifying device is as the switching device of AC-to DC, and require one-way conduction characteristic, namely during forward conduction, cut-in voltage is low, and conducting resistance is little, and time oppositely, blocking voltage is high, and reverse leakage is little.

Schottky barrier diode employs many decades in application of power field as rectifying device.For PN junction diode, Schottky barrier diode has the advantage that forward cut-in voltage is low and switching speed is fast, and this makes it be applicable to very much being applied to Switching Power Supply and high frequency occasion.The reverse recovery time of Schottky barrier diode is very short, and this time determines primarily of the parasitic capacitance of device, and determines sub-recombination time by less unlike PN junction diode.Therefore, Schottky-barrier diode rectifier can effectively reduce switch power loss.

Schottky barrier diode is that the metal-semiconductor junction principle utilizing metal and semiconductor contact to be formed makes.Traditional planar type Schottky barrier diode device is made up of with the N-epitaxially grown layer of the low doping concentration being positioned at top the N+substrate of the high-dopant concentration being positioned at below usually, N+substrate floor deposition the lower metal layer of high-dopant concentration forms ohmic contact, forms the negative electrode of Schottky barrier diode; The upper metal level of N-epitaxially grown layer end face deposition of low doping concentration forms Schottky Barrier Contact, forms the anode of Schottky barrier diode.The work function difference of metal and n type single crystal silicon forms potential barrier, and the height of this potential barrier determines the characteristic of Schottky barrier diode, and lower potential barrier can reduce forward conduction cut-in voltage, but reverse leakage can be made to increase, and reverse BV reduces; Otherwise higher potential barrier can increase forward conduction cut-in voltage, make reverse leakage reduce, reverse blocking capability strengthens simultaneously.But compared with pn junction diode, traditional planar type Schottky barrier diode on the whole reverse leakage is large, and reverse BV is low.

The distinguishing feature of channel schottky barrier diode is the grid structure that there is similar groove MOS device in N-epitaxial loayer, namely perpendicular to silicon chip surface, the groove extended in N-epitaxial loayer, cover the gate oxide of flute surfaces, and fill the grid of electric conducting material formation wherein.Device architecture as shown in Figure 1, the silicon chip of making devices is made up of highly doped N+ substrate 1 and more low-doped N-epitaxial loayer 2, a series of groove 3 is prepared in N-epitaxial loayer 2, it is n type single crystal silicon boss structure 4 between groove 3, groove 3 sidewall growth has silicon dioxide layer 5, upper metal level 6 covers the upper surface of total, and contacts with the end face of monocrystalline silicon boss structure 4 and form Schottky contacts face, forms the anode of Schottky diode rectifying device.Lower metal layer 8 is had to form the negative electrode of Schottky diode rectifying device at N+ substrate 1 bottom surface deposition.For different gash depths, electric-field intensity distribution curve when device reverse bias is calculated.The reverse voltage blocking ability of the area respective devices that electric field strength profile surrounds.Due to the existence of trench gate structure, during device reverse bias, Electric Field Distribution changes, and reaches the strongest bottom gate groove, and the electric field strength arriving schottky barrier interface reduces, thus enhances the voltage reversal blocking ability of this device, reduces reverse leakage current.Except the gate groove degree of depth, gate oxide thickness and boss structure region dopant concentration can modulation device reverse bias time Electric Field Distribution.

But the subject matter that this structural design exposes is that the lifting of device reverse voltage blocking ability is limited.With gash depth change, maximum field strength position changes thereupon, but area change that electric field strength profile surrounds is not remarkable, and namely device reverse voltage blocking ability is without remarkable change.In addition, the metal of filling in groove is identical with upper metal level, when groove width is narrower, because the gap filling capability of upper metal layer material is bad, likely leaves cavity, affects the reliability of device.For this reason, how to solve the problem become those of ordinary skill in the art make great efforts direction.

Summary of the invention

The object of the invention is to provide a kind of high pressure resistant plough groove type rectifying device, this high pressure resistant plough groove type rectifying device improves the reliability of device, potential lines density reduces at the top of groove, reduce further the electric leakage of device, and enhance device reverse voltage blocking ability, and for device performance adjustment more flexibilities are provided.

For achieving the above object, the technical solution used in the present invention is: a kind of high pressure resistant plough groove type rectifying device, in top plan view, the active area of this device is made up of several Schottky barrier diode unit cell parallel connections, on the longitudinal cross-section of this Schottky barrier diode unit cell, each Schottky barrier diode unit cell comprises and is positioned at silicon chip back side lower metal layer, be positioned at the substrate layer of heavy doping first conduction type above described lower metal layer, ohmic contact is formed between this substrate layer and lower metal layer, be positioned at the epitaxial loayer being provided with light dope first conduction type above described substrate layer, be positioned at above described epitaxial loayer and be provided with metal level, one groove is from described epitaxial loayer upper surface and extend in the middle part of epitaxial loayer, Schottky Barrier Contact face is formed between this epitaxial loayer end face and upper metal level,

One gate groove is positioned at described groove, one conductive polycrystalline silicon body embeds in described gate groove, in the polysilicon middle and lower part of conductive polycrystalline silicon body middle and lower part in gate groove and and be provided with the first silicon dioxide oxide layer between epitaxial loayer, the polysilicon top being positioned at conductive polycrystalline silicon body top is positioned at metal level, and between polysilicon top surrounding and upper metal level, be provided with the second silicon dioxide oxide layer, form ohmic contact face between described polysilicon top upper surface and upper metal level; Be positioned at described epitaxial loayer and have the second conduction type doped region at groove surrounding side surface, described in this, the second conduction type doped region and epitaxial loayer form pn junction interface.

The technical scheme improved further in technique scheme is as follows:

1. preferably, described second conduction type doped region and heavy doping second conduction type doped region opposite side have the extension layering of the first conduction type, this extension layering lower surface is higher than described second conduction type doped region lower surface, and this extension layering is positioned at epitaxial loayer top and the doping content of extension layering is greater than the doping content of epitaxial loayer.

2. preferably, the contact-making surface of described second conduction type doped region and single-crystal Si epitaxial layers is arcwall face.

3. preferably, the degree of depth of described second conduction type doped region is less than the degree of depth of gate groove.

Because technique scheme is used, the present invention compared with prior art has following advantages and effect:

1. the high pressure resistant plough groove type rectifying device of the present invention, it introduces the second conduction type doped region at the epitaxial loayer sidepiece higher than channel bottom, Electric Field Distribution when modulation device reverse bias, enhance device reverse voltage blocking ability, simultaneously, can for the second different conduction type doped region doping contents, the N-type region dopant concentration of the other side of epitaxial loayer that adjustment is corresponding with it, for device performance adjustment provides more flexibilities; Secondly, in addition, replace metal with conductive polycrystalline silicon, insert in groove, compare metal, conductive polycrystalline silicon has stronger gap filling capability, for device structure design provides more mobile types; Again, structure of the present invention is modulated further to Electric Field Distribution, after electric field strength occurs peak value near channel bottom, can continue to maintain higher value, improve direction blocking voltage.

2. the high pressure resistant plough groove type rectifying device of the present invention, its conductive polycrystalline silicon body embeds in gate groove, in the polysilicon middle and lower part of conductive polycrystalline silicon body middle and lower part in gate groove and and be provided with the first silicon dioxide oxide layer between epitaxial loayer, the polysilicon top being positioned at conductive polycrystalline silicon body top is positioned at metal level, and between polysilicon top surrounding and upper metal level, be provided with the second silicon dioxide oxide layer, ohmic contact face is formed between polysilicon top upper surface and upper metal level, improve the reliability of device, potential lines density reduces at the top of groove, reduce further the electric leakage of device.

Accompanying drawing explanation

Accompanying drawing 1 is the present invention's high pressure resistant plough groove type rectifying device structural representation.

In above accompanying drawing, 1, Schottky barrier diode unit cell; 2, lower metal layer; 3, substrate layer; 4, epitaxial loayer; 5, upper metal level; 6, groove; 7, monocrystalline silicon boss; 8, gate groove; 9, conductive polycrystalline silicon; 91, polysilicon middle and lower part; 92, polysilicon top; 101, the first silicon dioxide oxide layer; 102, the second silicon dioxide oxide layer; 11, the second conduction type doped region; 12, heavy doping second conduction type doped region; 13, Schottky Barrier Contact face; 14, ohmic contact face.

Embodiment

Below in conjunction with drawings and Examples, the invention will be further described:

Embodiment: a kind of high pressure resistant plough groove type rectifying device, in top plan view, the active area of this device is made up of several Schottky barrier diode unit cell 1 parallel connections, on the longitudinal cross-section of this Schottky barrier diode unit cell 1, each Schottky barrier diode unit cell 1 comprises and is positioned at silicon chip back side lower metal layer 2, be positioned at the substrate layer 3 of heavy doping first conduction type above described lower metal layer 2, ohmic contact is formed between this substrate layer 3 and lower metal layer 2, be positioned at the epitaxial loayer 4 being provided with light dope first conduction type above described substrate layer 3, be positioned at above described epitaxial loayer 4 and be provided with metal level 5, one groove 6 is from described epitaxial loayer 4 upper surface and extend in the middle part of epitaxial loayer 4, Schottky Barrier Contact face 13 is formed between this epitaxial loayer 4 end face and upper metal level 5, one gate groove 8 is positioned at described groove 6, one conductive polycrystalline silicon body 9 embeds in described gate groove 8, in the polysilicon middle and lower part 91 of conductive polycrystalline silicon body 9 middle and lower part in gate groove 8 and and be provided with the first silicon dioxide oxide layer 101 between epitaxial loayer 4, the polysilicon top 92 being positioned at conductive polycrystalline silicon body 9 top is positioned at metal level 5, and between polysilicon top 92 surrounding and upper metal level 5, be provided with the second silicon dioxide oxide layer 102, form ohmic contact face 14 between described polysilicon top 92 upper surface and upper metal level 5, be positioned at described epitaxial loayer 4 and have the second conduction type doped region 11 at groove 6 surrounding side surface, described in this, the second conduction type doped region 11 forms pn junction interface with epitaxial loayer 4.

Above-mentioned second conduction type doped region 11 and heavy doping second conduction type doped region 13 opposite side have the extension layering 13 of the first conduction type, this extension layering 13 lower surface is higher than described second conduction type doped region 11 lower surface, and this extension layering 14 is positioned at epitaxial loayer 4 top and the doping content of extension layering 13 is greater than the doping content of epitaxial loayer 4.

Above-mentioned second conduction type doped region 11 is arcwall face with the contact-making surface of single-crystal Si epitaxial layers 6.

The degree of depth of above-mentioned second conduction type doped region 11 is less than the degree of depth of gate groove 8.

When adopting above-mentioned high pressure resistant plough groove type rectifying device, Electric Field Distribution when modulation device reverse bias, enhance device reverse voltage blocking ability, for device performance adjustment provides more flexibilities, structure of the present invention is modulated further to Electric Field Distribution, after electric field strength occurs peak value near channel bottom, can continue to maintain higher value, improve direction blocking voltage; Secondly, which improve the reliability of device, potential lines density reduces at the top of groove, reduce further the electric leakage of device.

Above-described embodiment, only for technical conceive of the present invention and feature are described, its object is to person skilled in the art can be understood content of the present invention and implement according to this, can not limit the scope of the invention with this.All equivalences done according to Spirit Essence of the present invention change or modify, and all should be encompassed within protection scope of the present invention.

Claims (3)

1. a high pressure resistant plough groove type rectifying device, in top plan view, the active area of this device is made up of several Schottky barrier diode unit cell (1) parallel connections, on the longitudinal cross-section of this Schottky barrier diode unit cell (1), each Schottky barrier diode unit cell (1) comprises and is positioned at silicon chip back side lower metal layer (2), be positioned at the substrate layer (3) of described lower metal layer (2) top heavy doping first conduction type, ohmic contact is formed between this substrate layer (3) and lower metal layer (2), be positioned at the epitaxial loayer (4) that described substrate layer (3) top is provided with light dope first conduction type, be positioned at described epitaxial loayer (4) top and be provided with metal level (5), one groove (6) from described epitaxial loayer (4) upper surface and extend to epitaxial loayer (4) middle part, Schottky Barrier Contact face (13) is formed between this epitaxial loayer (4) end face and upper metal level (5), it is characterized in that: a gate groove (8) is positioned at described groove (6), one conductive polycrystalline silicon body (9) embeds in described gate groove (8), the polysilicon middle and lower part (91) being positioned at conductive polycrystalline silicon body (9) middle and lower part be positioned at gate groove (8) and and be provided with the first silicon dioxide oxide layer (101) between epitaxial loayer (4), the polysilicon top (92) being positioned at conductive polycrystalline silicon body (9) top is positioned at metal level (5), and between polysilicon top (92) surrounding and upper metal level (5), be provided with the second silicon dioxide oxide layer (102), ohmic contact face (14) is formed between described polysilicon top (92) upper surface and upper metal level (5), be positioned at described epitaxial loayer (4) and have the second conduction type doped region (11) at groove (6) surrounding side surface, the second conduction type doped region (11) described in this and epitaxial loayer (4) form pn junction interface.

2. high pressure resistant plough groove type rectifying device according to claim 1, is characterized in that: described second conduction type doped region (11) is arcwall face with the contact-making surface of single-crystal Si epitaxial layers (6).

3. high pressure resistant plough groove type rectifying device according to claim 1, is characterized in that: the degree of depth of described second conduction type doped region (11) is less than the degree of depth of gate groove (8).