CN206697480U - A kind of Schottky diode of p-type polysilicon groove structure - Google Patents
A kind of Schottky diode of p-type polysilicon groove structure Download PDFInfo
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- CN206697480U CN206697480U CN201720378020.1U CN201720378020U CN206697480U CN 206697480 U CN206697480 U CN 206697480U CN 201720378020 U CN201720378020 U CN 201720378020U CN 206697480 U CN206697480 U CN 206697480U
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Abstract
The utility model discloses a kind of Schottky diode of p-type polysilicon groove structure, the trench interiors are formed sediment by polysilicon to be set completely, and the polysilicon is p-type DOPOS doped polycrystalline silicon.The utility model substitutes the oxide layer inside traditional trench schottky structured channel and the filling mode of N-type polycrystalline silicon with p-type polysilicon, reaching reduces the purpose of cut-in voltage under high current, by adjusting polysilicon doping concentration, the effect for improving breakdown voltage can be reached.
Description
Technical field
Semiconductor applications are the utility model is related to, more precisely a kind of Schottky two of p-type polysilicon groove structure
Pole pipe.
Background technology
Schottky diode occupies one with its good forward conduction characteristic and high-speed switch speed in power device field
The ground of seat, but due to using metal-semiconductor contact on itself making, it is reversely pressure-resistant out of condition.In the prior art,
Electric field has been focused on channel bottom by the Schottky diode of groove type metal oxide semiconductor structure, improves other positions
The voltage dividing ability of depletion region, the breakdown reverse voltage of device is effectively raised, and the forward conduction under high-voltage great-current is electric
Pressure is not but very good.On the premise of other specification is not influenceed, improve the forward direction under Schottky diode high-voltage great-current
Conducting voltage has highly important meaning.Cut-in voltage mistake of the existing trench schottky structure devices under high-voltage great-current
Greatly, still there are many improvement spaces.
Utility model content
The purpose of this utility model is to provide a kind of Schottky diode of p-type polysilicon groove structure, and it can be realized
In trench schottky diode, groove type metal oxide semiconductor structure is replaced with the structure of plough groove type PN junction, and not
In the case of changing epitaxial conditions, the purpose of forward conduction voltage of the device under high current and high temperature can be reduced, also simultaneously
Breakdown reverse voltage can further be improved.
The utility model uses following technical scheme：
A kind of p-type polysilicon trench schottky diode, including some grooves, the trench interiors are formed sediment by polysilicon to be set
It is full, and the polysilicon is p-type DOPOS doped polycrystalline silicon.
The groove is in N-type epitaxy layer.
The N-type epitaxy layer is not provided with the side of groove on N-type substrate.
In the side deposition insulating layer of N-type epitaxy layer, and the insulating barrier is deposited in N-type epitaxy layer and the top of groove
Portion, form termination environment.
The deposited metal above the non-deposition insulating layer part of N-type epitaxy layer and insulating barrier, form anode.
A kind of preparation method for preparing p-type polysilicon trench schottky diode, comprises the following steps：
The depositing polysilicon in groove, first deposit layer polysilicon, implanting p-type impurity, regulation implantation dosage and
Implantation Energy, impurity is injected into polysilicon surface；
The second polysilicon is deposited, trench fill is expired, and is annealed, is uniformly distributed impurity concentration inside polysilicon.
It is further comprising the steps of：Insulating barrier deposits, and removes cellular region surface insulation material, only retains in termination environment.
Deposited metal, and perform etching, anneal, anode of the extraction electrode as device is formed, this metal level is by multilayer
Metal level is formed.
The utility model has the advantages that：By the oxide layer and N-type polycrystalline silicon inside traditional trench schottky structured channel
Filling mode substituted with p-type polysilicon, reach reduce high current under cut-in voltage purpose, it is dense by adjusting polysilicon doping
Degree, the effect for improving breakdown voltage can be reached.
Brief description of the drawings
The utility model is described in detail with reference to embodiment and accompanying drawing, wherein：
Fig. 1 is structural representation of the present utility model.
Fig. 2 to Fig. 8 is the structure chart of preparation method intermediate structure of the present utility model.
Fig. 9 is emulation log curve map of the diode with prior art breakdown reverse voltage of utility model.
Figure 10 is diode of the present utility model figure compared with prior art cut-in voltage.
Embodiment
Specific embodiment of the present utility model is expanded on further below in conjunction with the accompanying drawings：
As shown in figure 1, the utility model discloses a kind of Schottky diode of p-type polysilicon groove structure, if including
Hondo groove 23, and the trench interiors of the groove 23 are formed sediment by polysilicon 40 and set completely, and the polysilicon 40 is p-type doped polycrystalline
Silicon.
The utility model fills polysilicon and N doped with p type impurity in the trench based on trench schottky technique
Type epitaxial layer forms PN junction structure.When device is positive to work, when applying less operating voltage, have compared with low turn-on voltage
Schottky junction first turns on, and with alive increase is applied, PN junction also begins to turn on, and starts as a large amount of electronics of drift region injection,
The conducting resistance in drift region is reduced, its forward conduction voltage is reduced under high current working condition.
In trench schottky structure of the present utility model, the polysilicon adulterated with p-type substitutes original gate oxide and N-type
DOPOS doped polycrystalline silicon, the cut-in voltage under device high-voltage great-current is reduced, while improve breakdown reverse voltage.
Under with a epitaxial conditions, with the increase of p-type polysilicon doping concentration in groove, breakdown voltage is in first to rise
Downward trend afterwards.Reason is that p-type polysilicon contacts to form a PN junction with N-type epitaxy layer, during device reverse operation, this PN junction
Together with overlapping with the depletion layer of the schottky junction on surface, play a part of sharing surface field.When p-type polysilicon doping concentration
When too high or too low, i.e., p-type polysilicon dopant concentration mismatches with extension concentration, and PN junction punctures in advance, has dragged down whole device
The breakdown voltage of part.When p-type polysilicon dopant concentration matches with epitaxial layer concentration, the electricity at the place of surface schottky junction can be reduced
, so as to lift the breakdown voltage of device.
The utility model will be filled out originally on the basis of the Schottky diode of groove type metal oxide semiconductor structure
The gate oxide and N-type polycrystalline silicon filled in groove is substituted with p-type polysilicon, reduces the cut-in voltage under high current, together
When also further improve the breakdown reverse voltage of device.
Groove 23 is in N-type epitaxy layer 20.The side that the N-type epitaxy layer 20 is not provided with groove is located at N-type substrate 10
On.
In the side deposition insulating layer 50 of N-type epitaxy layer 20, and the insulating barrier is deposited in N-type epitaxy layer 20 and groove
Top, formed termination environment.The deposited metal 60 above the non-deposition insulating layer part of N-type epitaxy layer 20 and insulating barrier, formed
Anode.
Terminal structure of the present utility model extends to be formed using the groove of multiple filling p-type polysilicons to chip edge, eventually
End groove makes simultaneously with cellular groove, and this structure can effectively reduce the distribution of active area electric field, so as to lift device
Breakdown voltage.Spacing, width can be set according to the pressure-resistant demand of device between groove.
The invention also discloses the preparation method of the Schottky diode of p-type polysilicon groove structure, including it is following
Step：
Grown as shown in Fig. 2 carrying out extension 20 on N-type substrate 10.Selected according to the property requirements of Schottky diode
Suitable extension disk, the disk are made up of the substrate of low-resistivity and the epitaxial layer of specific electric resistance.
As shown in figure 3, deposit masking layer 21 and photoresist 22 carry out trench lithography, masking layer etching.It is raw on epitaxial layer
Long one layer of masking layer, the effect of the masking layer is to provide masking for etching groove below, shelters the composition of layer material and can be
Silica, silicon nitride or both combine；Trench lithography is carried out, and masking layer is performed etching, etches etching groove window.
As shown in figure 4, removing photoresist 22, carry out groove 23 and etch.Photoresist is removed, etching groove is carried out, is sheltering
Groove is formed under the masking action of layer.
As shown in figure 5, depositing polysilicon 30, first deposits the polysilicon of layer, implanting p-type impurity, adjusts injectant
Amount and Implantation Energy, polysilicon surface is injected into by impurity.Masking layer is removed, carries out sacrifice oxidation, and remove removing oxide layer；Deposit
Polysilicon, the polysilicon of layer is first deposited, implanting p-type impurity, implantation dosage and Implantation Energy is adjusted, impurity is injected into
Polysilicon surface.Because the non-impurity-doped polysilicon of first step deposit is relatively thin, Implantation Energy control is inclined in 5~15kev, injection
Rake angle is 7 °, is controlled in the range of guaranteeing to be injected into trenched side-wall and bottom polysilicon, implanted dopant is generally
Boron.Then second step deposits thicker non-impurity-doped polysilicon again, is filled up completely with groove, annealing, use of the present utility model
Condition be 950 DEG C 30 minutes, impurity is uniformly spread, obtain final p-type polysilicon.
As shown in fig. 6, depositing polysilicon 40 again, trench fill is expired, and annealed, make impurity inside polysilicon dense
Degree is uniformly distributed.
As shown in fig. 7, removing surface is more than polysilicon, polysilicon surface in groove is set to maintain an equal level with epitaxial layer silicon face, and
Remove masking layer.
As shown in figure 8, insulating barrier 50 deposits, cellular region surface insulation material is removed, is only retained in termination environment.
Deposited metal 60, and perform etching, anneal, anode of the extraction electrode as device is formed, this metal level is by more
Layer metal level is formed, and is common process, is obtained structure as shown in Figure 1.Deposited metal, and photoetching, etching are carried out, and formed
Anode of the extraction electrode as device, this metal level are made up of more metal layers, under rapid thermal anneal process with N-type silicon epitaxy
Layer forms Schottky contacts, and between 600 DEG C~800 DEG C, the time is less than 2 minutes annealing temperature.
It is thinned at the back side of N-type silicon chip, then deposited metal, such as silver, gold or other Low ESR alloy-layers,
Negative electrode as device.
As shown in Fig. 9,10, mutually homepitaxy lower groove metal-oxide-semiconductor structure and structure described in the utility model
The emulation log curve maps of breakdown reverse voltage, curve a are the breakdown voltage curve of the utility model structure, and another is common
Trench schottky structure breakdown voltage curve, conventional trench Schottky junction structure breakdown voltage curve are 46.1V, the utility model institute
It is 58.4V to state structure breakdown curve, it can be seen that the breakdown voltage of structure of the present utility model significantly improves.
Cut-in voltage compares, and curve a is structure cut-in voltage curve described in the utility model, and another curve is conventional trench
Schottky junction structure cut-in voltage curve, it can be seen that in the case of high current, the cut-in voltage of the utility model structure substantially reduces.
The utility model has the good breakdown reverse voltage of PN junction diode and Schottky diode good just simultaneously
To on state characteristic.During reverse operation, the PN junction and the depletion layer of schottky junction that are formed at groove overlap in device surface, reduce
The electric-field intensity on schottky junction surface, the doping concentration by adjusting polysilicon are allowed to match with extension concentration, and it is anti-to reach raising
To the purpose of breakdown voltage.During forward direction work, when applying less operating voltage, have first compared with the schottky junction of low turn-on voltage
Conducting, with alive increase is applied, PN junction also begins to turn on, and starts, as a large amount of few sons of drift region injection, to reduce drift
Conducting resistance in area, its forward conduction voltage is reduced under high current working condition.
Compared according to simulation result under the same terms, the p-type polysilicon groove structure in the utility model is than traditional ditch
Slot structure is compared, and the conducting voltage under high current significantly reduces, by adjusting the dopant concentration of polysilicon, breakdown reverse voltage
Also can be improved.
Preferred embodiment of the present utility model is the foregoing is only, it is all at this not to limit the utility model
All any modification, equivalent and improvement made within the spirit and principle of utility model etc., should be included in the utility model
Protection domain within.
Claims (5)
1. a kind of p-type polysilicon trench schottky diode, it is characterised in that including some grooves, the trench interiors pass through
Polysilicon, which forms sediment, to be set completely, and the polysilicon is p-type DOPOS doped polycrystalline silicon.
2. p-type polysilicon trench schottky diode according to claim 1, it is characterised in that the groove is located at N-type
In epitaxial layer.
3. p-type polysilicon trench schottky diode according to claim 2, it is characterised in that the N-type epitaxy layer is not
If fluted side is on N-type substrate.
4. p-type polysilicon trench schottky diode according to claim 3, it is characterised in that the one of N-type epitaxy layer
Outgrowth insulating barrier, and the insulating barrier is deposited in N-type epitaxy layer and the top of groove, forms termination environment.
5. p-type polysilicon trench schottky diode according to claim 4, it is characterised in that do not formed sediment in N-type epitaxy layer
Deposited metal above product insulation layer segment and insulating barrier, forms anode.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720378020.1U CN206697480U (en) | 2017-04-12 | 2017-04-12 | A kind of Schottky diode of p-type polysilicon groove structure |
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| CN201720378020.1U CN206697480U (en) | 2017-04-12 | 2017-04-12 | A kind of Schottky diode of p-type polysilicon groove structure |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106952942A (en) * | 2017-04-12 | 2017-07-14 | 上海格瑞宝电子有限公司 | A kind of Schottky diode of p-type polysilicon groove structure and preparation method thereof |
| CN113517193A (en) * | 2021-04-06 | 2021-10-19 | 江苏新顺微电子股份有限公司 | Process method for improving performance of trench MOS structure Schottky diode |
-
2017
- 2017-04-12 CN CN201720378020.1U patent/CN206697480U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106952942A (en) * | 2017-04-12 | 2017-07-14 | 上海格瑞宝电子有限公司 | A kind of Schottky diode of p-type polysilicon groove structure and preparation method thereof |
| CN113517193A (en) * | 2021-04-06 | 2021-10-19 | 江苏新顺微电子股份有限公司 | Process method for improving performance of trench MOS structure Schottky diode |
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