CN109935625A - A kind of schottky diode device and manufacturing method - Google Patents
A kind of schottky diode device and manufacturing method Download PDFInfo
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- CN109935625A CN109935625A CN201711350665.5A CN201711350665A CN109935625A CN 109935625 A CN109935625 A CN 109935625A CN 201711350665 A CN201711350665 A CN 201711350665A CN 109935625 A CN109935625 A CN 109935625A
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Abstract
The invention belongs to technology of semiconductor chips field, a kind of schottky diode device and manufacturing method are provided, includes semiconductor substrate, epitaxial layer, multiple deep trouths, dielectric layer, polysilicon, metal electrode layer in schottky diode device provided by the invention；Make in the schottky region between adjacent first dielectric layer the pinch off drift region under lower bias by using the first relatively thin dielectric layer, so that metal electrode layer is kept low in backward voltage elevation process with the electric field strength at epitaxial layer interface, and the second thicker dielectric layer makes polysilicon carry out having lateral depletion to the drift region of adjacent dielectric interlayer, to form two-dimensional reduction surface field effect, it avoids schottky diode device and causes punch through the problem of voltage reduces since the electric field strength of metal electrode layer and epitaxial layer interface is excessively high, the conducting voltage of schottky diode device is reduced under conditions of not reducing breakdown voltage.
Description
Technical field
The present invention relates to technology of semiconductor chips field more particularly to a kind of schottky diode devices and manufacturing method.
Background technique
Currently, diode is as a kind of widely used device integrated with the continuous development of semiconductor integrated circuit
Increasingly important role is played in circuit.Diode has two types, and one is PN junction (Positive Negative
Junction, PN junction) diode, one is the Schottky diodes based on metal-semiconductor contact.Schottky diode is opposite
PN junction diode has lower conducting voltage, can reduce the loss in conducting, the conducting voltage master of Schottky diode
It to be determined by the resistance of the barrier height and drift region of metal and semiconductor, the smaller electric conduction of the barrier height of metal and semiconductor
Hinder smaller, but the too small electric leakage that will increase Schottky diode of barrier height is to increase the loss of Schottky diode.
However, the resistance for reducing drift region needs to be promoted the doping concentration of drift region or reduces the thickness of epitaxial layer,
The breakdown voltage that Schottky diode is born usually is also reduced while reducing the conducting voltage of Schottky diode.
Summary of the invention
The purpose of the present invention is to provide a kind of schottky diode device and manufacturing methods, can be to avoid in reduction Xiao Te
The problem of voltage reduces is caused punch through when the conducting voltage of based diode device.
Schottky diode device provided by the invention includes: semiconductor substrate；It is formed on the semiconductor substrate
Epitaxial layer, wherein the epitaxial layer offers multiple deep trouths；It is formed in the dielectric layer of the deep trouth inner wall；It is formed in described
In deep trouth and positioned at the polysilicon between the dielectric layer；And it is formed in the epitaxial layer between the adjacent deep trouth
The metal electrode layer on surface, the metal electrode layer are connected by contact hole with the polysilicon；Wherein, the dielectric layer is extremely
It less include first dielectric layer with first thickness and the second dielectric layer with second thickness, first dielectric layer
Close to the deep trouth opening direction, second dielectric layer is less than described close to the bottom of the deep trouth, the first thickness
Second thickness.
Preferably, first dielectric layer is located above the side wall of the deep trouth, and second dielectric layer is located at institute
State the side wall lower section and the bottom of the deep trouth of deep trouth.
Preferably, the dielectric layer further includes the third dielectric layer with third thickness, and the third thickness is greater than
The first thickness and it is less than the second thickness, the third dielectric layer is located at first dielectric layer and described second
Between dielectric layer and both ends are contacted with first dielectric layer and second dielectric layer respectively.
Preferably, the dielectric layer further includes the 4th dielectric layer with the 4th thickness, the 4th dielectric layer
Between first dielectric layer and second dielectric layer and both ends respectively with first dielectric layer and institute
State the contact of the second dielectric layer, the 4th thickness of the 4th dielectric layer along second dielectric layer to described first
It is gradually become smaller on the direction of dielectric layer.
Preferably, the dielectric layer is silica.
To solve the above-mentioned problems, the present invention also provides a kind of manufacturing methods of schottky diode device, including with
Lower step:
Step 1: on a semiconductor substrate by being epitaxially-formed epitaxial layer；
Step 2: depositing the first exposure mask on said epitaxial layer there；
Step 3: carrying out deep etching to the epitaxial layer, it is deposited with other than first exposure mask on said epitaxial layer there
Position perform etching to form deep trouth；
Step 4: removal first exposure mask, forms dielectric layer in the epi-layer surface；
Step 5: the deposit polycrystalline silicon in the deep trouth for being formed with the dielectric layer, and the polysilicon is performed etching
First groove is formed, the first groove has the first depth；
Step 6: being performed etching to the part in the dielectric layer close to the deep trouth opening direction so that the electricity is situated between
Matter layer includes first dielectric layer with first thickness and the second dielectric layer with second thickness, first dielectric
Layer is less than institute close to the bottom of the deep trouth, the first thickness close to the deep trouth opening direction, second dielectric layer
State second thickness；
Step 7: deposit polycrystalline silicon makes the surface of the polysilicon and the adjacent deep trouth in the first groove
Between epi-layer surface flush.
Step 8: the epi-layer surface between the adjacent deep trouth forms metal electrode layer, the metal electrode layer
It is connected with the polysilicon.
Preferably, further include following step before the step 7 after the step 6:
Second dielectric layer is performed etching to form the third dielectric layer with third thickness, so that the third
Thickness be greater than the first thickness and be less than the second thickness, the third dielectric layer be located at first dielectric layer and
It is contacted between second dielectric layer and with first dielectric layer and second dielectric layer.
Preferably, further include following step before the step 7 after the step 6:
Second dielectric layer is performed etching to form the 4th dielectric layer with the 4th thickness, so that the described 4th
4th thickness of dielectric layer is less than the second thickness and is greater than the first thickness, and the 4th dielectric layer is located at described
Between first dielectric layer and second dielectric layer and both ends respectively with first dielectric layer and it is described second electricity
Dielectric layer contact, the 4th thickness of the 4th dielectric layer along second dielectric layer to first dielectric layer
Direction on gradually become smaller.
Preferably, first mask plate is dura mater, and the ingredient of the dura mater is oxide and/or nitride.
Preferably, the dielectric layer is silica.
In schottky diode device and manufacturing method provided by the invention, included at least in schottky diode device
Semiconductor substrate；Form epitaxial layer on the semiconductor substrate, wherein the epitaxial layer offers multiple deep trouths；It is formed
In the dielectric layer of the deep trouth inner wall；It is formed in the polysilicon in the deep trouth and being located between the dielectric layer；And
It is formed in the metal electrode layer of the epi-layer surface between the adjacent deep trouth, the metal electrode layer passes through contact hole
It is connected with the polysilicon；Wherein, the dielectric layer includes at least the first dielectric layer with first thickness and with the
Second dielectric layer of two thickness, first dielectric layer are leaned on close to the deep trouth opening direction, second dielectric layer
The bottom of the nearly deep trouth, the first thickness are less than the second thickness.Make by using the first relatively thin dielectric layer
The drift region that one pinch-off voltage pinch off epitaxial layer is formed is formed on the top of adjacent dielectric interlayer schottky region, to shield gold
Belong to the interface of electrode layer and epitaxial layer so that the electric field strength between metal electrode layer and epitaxial layer was increased in backward voltage
It is kept low in journey, and the second thicker dielectric layer carries out having lateral depletion to the drift region of adjacent dielectric interlayer,
To forming two-dimensional reduction surface field effect, avoid schottky diode device in backward voltage elevation process due to
The electric field strength of metal electrode layer and epitaxial layer interface is excessively high and causes punch through the problem of voltage reduces, and is not reducing breakdown voltage
Under conditions of reduce the conducting voltage of schottky diode device.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of the schottky diode device provided in the embodiment of the present invention one；
Fig. 2 is the structural schematic diagram of the schottky diode device provided in the embodiment of the present invention two；
Fig. 3 is the structural schematic diagram of the schottky diode device provided in the embodiment of the present invention three；
Fig. 4 is in a kind of manufacturing method of the schottky diode device provided in the embodiment of the present invention in semiconductor substrate
The upper structural schematic diagram for forming epitaxial layer；
Fig. 5 is to sink on epitaxial layer in a kind of manufacturing method of the schottky diode device provided in the embodiment of the present invention
The structural schematic diagram of the first exposure mask of product；
Fig. 6 is to carry out in a kind of manufacturing method of the schottky diode device provided in the embodiment of the present invention to epitaxial layer
The structural schematic diagram of deep etching formation deep trouth；
Fig. 7 is formed in deep trouth in the manufacturing method for a kind of schottky diode device provided in the embodiment of the present invention
The structural schematic diagram of second dielectric layer；
Fig. 8 is deposited in deep trouth in the manufacturing method for a kind of schottky diode device provided in the embodiment of the present invention
The structural schematic diagram of polysilicon；
Fig. 9 is in a kind of manufacturing method of the schottky diode device provided in the embodiment of the present invention to the second dielectric
Layer performs etching the structural schematic diagram that the first dielectric layer is formed above deep trouth side wall；
Figure 10 is to carry out in a kind of manufacturing method of the schottky diode device provided in the embodiment of the present invention to deep trouth
Structural schematic diagram after deposit.
Figure 11 is in a kind of manufacturing method of the schottky diode device provided in the embodiment of the present invention in adjacent deep trouth
Between epitaxial layer on formed metal electrode layer structural schematic diagram.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
In the description of the present invention, it is to be understood that, term " first ", " second " are used for description purposes only, and cannot
It is interpreted as indication or suggestion relative importance or implicitly indicates the quantity of indicated technical characteristic.Define as a result, " the
One ", the feature of " second " can explicitly or implicitly include one or more of the features.
The embodiment of the present invention one provides a kind of schottky diode device.As shown in Figure 1, the Schottky in the present embodiment
Diode component, comprising: semiconductor substrate 1 forms epitaxial layer 2 on semiconductor substrate 1；Epitaxial layer 2 offers multiple depths
Slot is formed in the dielectric layer 3 of deep trouth inner wall, is formed in deep trouth and is located at the dielectric layer 3 on same deep trouth two sidewalls
Between polysilicon 4, be formed in the metal electrode layer 5 on 2 surface of epitaxial layer between adjacent deep trouth, metal electrode layer 5 passes through
Contact hole is connected with polysilicon 4；Dielectric layer 3 includes having the first dielectric layer 3a of first thickness and with second thickness
Second dielectric layer 3b, the first dielectric layer 3a is close to deep trouth opening direction, and the second dielectric layer 3b is close to the bottom of deep trouth, and
One thickness is less than second thickness.Specifically, dielectric layer 3 between polysilicon 4 and epitaxial layer 2, is isolated by dielectric layer 3
The contact of polysilicon 4 and epitaxial layer 2.The thickness of dielectric layer 3 refers to the distance between its surface and deep trouth surface.
Specifically, semiconductor substrate 1 is N-type substrate, the cathode of schottky diode device, semiconductor substrate can be used as
In 1 doped with concentration be 1e19/cm3N-type element, the resistance of semiconductor substrate 1 can be greatly reduced, specifically, N-type element
For nitrogen, Lin Deng V race (the 5th main group) element.Epitaxial layer 2 above semiconductor substrate 1 is formed outside N-type doped with N-type element
Prolong layer, the doping concentration and thickness of epitaxial layer 2 are configured according to the breakdown voltage of schottky diode device, usual Schottky
The thicker breakdown voltage of epitaxial layer 2 of diode component is higher, the resistance for the drift region that the smaller epitaxial layer 2 of the concentration of doping is formed
It is higher that voltage is caused punch through more greatly.Metal electrode layer 5 is covered with above epitaxial layer 2, metal electrode layer 5 and polysilicon 4 are logical
It crosses contact hole to be connected, specifically, filling conductive metal in contact hole metal electrode layer 5 is connected with polysilicon 4, Schottky two
The electric leakage of pole pipe mostlys come from the barrier height of metal electrode layer 5 Yu epitaxial layer 2, the smaller Schottky diode of the barrier height
Electric leakage it is bigger.
Specifically, a kind of image charge can be generated when electronics is close to the interface of metal electrode layer 5 and epitaxial layer 2, the mirror
Mirror charge can reduce the barrier height between metal electrode layer 5 and epitaxial layer 2, to will increase the leakage of schottky diode device
Electricity, it is assumed that the barrier height difference between metal electrode layer 5 and epitaxial layer 2 isThen:
Wherein, q is the quantity of electric charge of electronics, electric field strength of the E between metal electrode layer 5 and epitaxial layer 2, εsFor epitaxial layer
2 dielectric constant.
Specifically, barrier height is poorThe radical sign of electric field strength E between metal electrode layer 5 and epitaxial layer 2 is at just
Than therefore, the electric field strength E between metal electrode layer 5 and epitaxial layer 2 is smaller, and barrier height is poorWith regard to smaller, metal at this time
Electrode layer 5 and the barrier height of epitaxial layer 2 are bigger, and the electric leakage of Schottky diode is with regard to smaller.
Specifically, forming the contact that deep trouth reduces metal electrode layer 5 with epitaxial layer 2 by deep etching in epitaxial layer 2
Area, such that the electric leakage of schottky diode device reduces.Due to being formed between metal electrode layer 5 and epitaxial layer 2
There are polysilicons 4 for schottky region two sides, and polysilicon 4 is connected with metal electrode layer 5, thus at lower voltages, polycrystalline
Silicon 4 can be completely depleted to shield the interface between metal electrode layer 5 and epitaxial layer 2 by drift region that epitaxial layer 2 is formed, this
When drain voltage when continuing growing, schottky diode device electric field intensity inside high directly proportional will not increase, it is assumed that polysilicon 4 can will
The complete depletion of voltage that exhausts in the drift region that epitaxial layer 2 is formed is Vp, then:
Wherein, NDIt is the doping concentration of epitaxial layer 2, CoxIt is the capacitor of dielectric layer, d is that electricity is situated between in adjacent different deep trouths
The distance between matter layer.
In the present embodiment, second thickness of the first thickness of the first dielectric layer 3a less than the second dielectric layer 3b, the
The first thickness of one dielectric layer 3a is smaller, and the drift region that the epitaxial layer 2 between the first dielectric layer 3a is formed is consumed by polysilicon 4
Most voltage is with regard to smaller, specifically, the drift region that epitaxial layer 2 is formed is leaned at lower voltages at this time close to metal electrode layer
Nearly metal electrode at drift region be depleted after form a pinch-off voltage, the drift region quilt between the first adjacent dielectric layer 3a
First potential barrier is formed after pinch off between metal electrode layer 5 and epitaxial layer 2, which inhibits Schottky barrier
Effect is reduced to reduce leakage current, on the other hand, is shielded between metal electrode layer 5 and epitaxial layer 2 by pinch off drift region
Interface, reduce the electric field strength of metal electrode layer 5 Yu 2 interface of epitaxial layer；The second thickness of second dielectric layer 3b is thicker,
Continue to continue in elevation process by transverse direction in backward voltage in the drift region that epitaxial layer 2 is formed between the second adjacent dielectric layer 3b
It exhausts, forms two-dimensional reduction surface field effect, form a new peak electric field inside schottky diode device, because
And when reducing Schottky diode conducting voltage using relatively thin epitaxial layer 2 or using the epitaxial layer 2 of higher-doped concentration,
Schottky diode device is avoided in backward voltage elevation process due to the electric field of metal electrode layer 5 and 2 interface of epitaxial layer
Intensity is excessively high and causes punch through the problem of voltage reduces, and Schottky diode device is reduced under conditions of not reducing breakdown voltage
The conducting voltage of part.
As a preferred embodiment of the present invention, the first dielectric layer 3a is located above the side wall of deep trouth, the second dielectric layer
3b is located at below the side wall of deep trouth and the bottom of deep trouth.
Fig. 2 is the structural schematic diagram of the schottky diode device provided in the embodiment of the present invention two, as shown in Fig. 2, electric
Dielectric layer 3 further includes the third dielectric layer 3c with third thickness, and the third thickness of third dielectric layer 3c is greater than the first electricity
The first thickness of dielectric layer 3a and less than the second thickness of the second dielectric layer 3b, third dielectric layer 3c is located at the first dielectric
Between layer 3a and the second dielectric layer 3b.Specifically, third dielectric layer 3c is also located between polysilicon 4 and epitaxial layer 2, work as Xiao
When the backward voltage at special based diode both ends is gradually increased, the drift region between the first adjacent electrolyte layer 3a is first by polycrystalline
Silicon 4 exhausts, since the thickness of the first dielectric layer 3a is minimum, the consumption of the drift region between the first adjacent at this time dielectric layer 3a
Voltage is minimum to the greatest extent, as the both ends backward voltage of Schottky diode continues growing, the consumption between dielectric layer 3 adjacent at this time
Directional Extension of the layer to semiconductor substrate 1 to the greatest extent is greater than the depletion layer institute between adjacent third dielectric layer 3c in backward voltage
When the voltage of receiving, the depletion layer between adjacent third dielectric layer 3c is exhausted by polysilicon 4, reaches second in backward voltage
When the maximum voltage that dielectric layer 3b can bear, Schottky diode is breakdown, which is breakdown voltage.
Fig. 3 is the structural schematic diagram of the schottky diode device provided in the embodiment of the present invention three, as shown in figure 3, electric
Dielectric layer 3 further includes the 4th dielectric layer 3d, and the 4th dielectric layer 3d is located at the first dielectric layer 3a and the second dielectric layer 3b
Between and both ends contacted respectively with the first dielectric layer 3a and the second dielectric layer 3b, the thickness of the 4th dielectric layer 3d is on edge
The second dielectric layer 3b gradually become smaller on the direction of the first dielectric layer 3a, i.e. the 4th dielectric layer 3d and deep trouth surface phase
Pair outer surface be arcwall face or inclined-plane.Specifically, being situated between by the first dielectric layer 3a to the electricity in the second direction dielectric layer 3b
Matter thickness degree gradually increases, and the voltage that exhausts for the drift region that the epitaxial layer 2 of adjacent dielectric interlayer is formed also gradually increases, and increases
The thickness of the stability of schottky diode device, the second dielectric layer 3b is maximum, so that the second dielectric layer 3b
The width and thickness of epitaxial layer 2 between thickness and the second adjacent dielectric layer 3b determine schottky diode device
Breakdown voltage avoids schottky diode device in backward voltage elevation process due to metal electrode layer 5 and 2 boundary of epitaxial layer
The electric field strength in face is excessively high and causes punch through the problem of voltage reduces, and Schottky is reduced under conditions of not reducing breakdown voltage
The conducting voltage of diode.
As a preferred embodiment of the present invention, dielectric layer is silica.
As a preferred embodiment of the present invention, dielectric layer is silicon nitride.
As a preferred embodiment of the present invention, the depth of the first adjacent dielectric layer 3a is identical.Specifically, adjacent
When the depth of one dielectric layer 3a is identical, the drift region that the epitaxial layer 2 between the first dielectric layer 3a is formed will more evenly, this is advantageous
It is completely depleted to drift region progress at the lower voltage in polysilicon 4, to shield metal electrode by pinch off drift region in advance
Interface between layer 5 and epitaxial layer 2, reduces the electric field strength of metal electrode layer 5 Yu 2 interface of epitaxial layer, avoids Schottky
Electric field strength of the diode component in backward voltage elevation process due to metal electrode layer 5 and 2 interface of epitaxial layer is excessively high and leads
The problem of causing breakdown voltage to reduce.
To solve the above-mentioned problems, the embodiment of the invention also provides a kind of manufacturing method of schottky diode device,
The following steps are included:
Step 1: on semiconductor substrate 1 by being epitaxially-formed epitaxial layer 2 (as shown in Figure 4)；Specifically, partly leading
Body substrate 1 is N-type substrate, can be used as the cathode of schottky diode device, is doped with concentration in semiconductor substrate 1
1e19/cm3N-type element, specifically, N-type element be nitrogen, Lin Deng V race (the 5th main group) element, semiconductor can be greatly reduced
The resistance of substrate 1.Epitaxial layer 2 above semiconductor substrate 1 forms N-type epitaxy layer doped with N-type element, epitaxial layer 2
Doping concentration and thickness are configured according to the breakdown voltage of schottky diode device, outside usual schottky diode device
Prolong that the thicker breakdown voltage of layer 2 is higher, the resistance for the drift region that the smaller epitaxial layer 2 of the concentration of doping is formed causes punch through more greatly
Voltage is higher.
Step 2: depositing the first exposure mask 100 (as shown in Figure 5) on epitaxial layer 2；Specifically, the first exposure mask 100 can be
Dura mater, material can be the combination of silica, the silica of nitride layer and any mode and nitride layer, mainly
For protecting epitaxial layer in subsequent deep etching and the position of the first exposure mask 100 being made to be used to form metal electrode layer 5.
Step 3: carry out deep etching to epitaxial layer 2, be deposited on epitaxial layer 2 position other than first exposure mask 100 into
Row etching forms deep trouth 101 (as shown in Figure 6)；Specifically, the etching process can be dry etching or wet etching, deep trouth
101 depth and width are determined according to the design parameter of schottky diode device.
Step 4: the first exposure mask 100 of removal, forms dielectric layer 3 (as shown in Figure 7) on the surface of the epitaxial layer 2；Tool
Body, use thermal oxidation method or sedimentation to form dielectric layer 3 after removing the first exposure mask 100 to the sample in step 3,
Sacrifice oxidation can also be added before forming dielectric layer 3 using dry method or wet process boiler tube growth silica technique in extension
2 surface of layer form the sacrificial oxidation film that thickness is about 500 angstroms, to ensure to repair the defect as brought by deep etching.Second
The thickness of dielectric layer 3 is determined with specific reference to the parameter of schottky diode device.
Step 5: the deposit polycrystalline silicon 4 in the deep trouth 101 for being formed with dielectric layer 3, and shape is performed etching to polysilicon 4
At with first groove, first groove is with the first depth (as shown in Figure 8)；Specifically, polysilicon 4 be N-type heavy doping, first
First depth of groove is determined according to the design parameter of device.
Step 6: being performed etching to the part in dielectric layer 3 close to deep trouth opening direction so that dielectric layer 3 includes tool
There are the first dielectric layer 3a of first thickness and the second dielectric layer 3b (as shown in Figure 9) with second thickness, the first electricity is situated between
Matter layer 3a is less than second thickness close to the bottom of deep trouth, first thickness close to deep trouth opening direction, the second dielectric layer 3b, specifically
, the first dielectric layer 3a is located above the side wall of deep trouth 101, the second dielectric layer 3b be located at deep trouth 101 side wall lower section and
The bottom of deep trouth 101, the first thickness that the first dielectric layer 3a has is less than the second thickness that the second dielectric layer 3b has.Electricity
The contact of polysilicon 4 and epitaxial layer 2 is isolated by dielectric layer 3 between polysilicon 4 and epitaxial layer 2 for dielectric layer 3.
Step 7: making the extension between the surface of polysilicon 4 and adjacent deep trouth in deposit polycrystalline silicon in first groove
2 surface of layer flush (as shown in Figure 10).Specifically, dielectric layer 3 passes through dielectric layer between polysilicon 4 and epitaxial layer 2
The contact of 3 isolation polysilicons 4 and epitaxial layer 2.In epitaxial layer 2 by deep etching formed deep trouth reduce metal electrode layer 5 with
The contact area of epitaxial layer 2, such that the electric leakage of schottky diode device reduces.
Step 8: 2 surface of epitaxial layer between adjacent deep trouth forms metal electrode layer 5 (as shown in figure 11), metal
Electrode layer 5 is connected with polysilicon 4.Since there are polycrystalline for the schottky region two sides that are formed between metal electrode layer 5 and epitaxial layer 2
Silicon 4, and polysilicon 4 is connected with metal electrode layer 5, it is at lower voltages, more when the thickness of the first dielectric layer 3a is smaller
Crystal silicon 4 can be completely depleted to shield the interface between metal electrode layer 5 and epitaxial layer 2 by drift region that epitaxial layer 2 is formed,
Schottky diode device is avoided in backward voltage elevation process due to the electric field of metal electrode layer 5 and 2 interface of epitaxial layer
Intensity is excessively high and causes punch through the problem of voltage reduces.
As a preferred embodiment in a kind of manufacturing method of schottky diode device provided by the invention, in step 6
Later, further include following step before step 7: the second dielectric layer 3b is performed etching to form the third with third thickness
Dielectric layer 3c, so that third thickness is greater than first thickness and is less than second thickness, third dielectric layer 3c is located at the first electricity and is situated between
Between matter layer 3a and the second dielectric layer 3b and both ends are contacted with the first dielectric layer 3a and the second dielectric layer 3b.Specifically
, third dielectric layer 3c is also located between polysilicon 4 and epitaxial layer 2, when the backward voltage at schottky diode device both ends
When being gradually increased, the drift region between the first adjacent electrolyte layer 3a is exhausted by polysilicon 4 first, due to the first dielectric layer
The thickness of 3a is minimum, and the drift region between the first adjacent at this time dielectric layer 3a exhausts voltage minimum, with Schottky two
The both ends backward voltage of pole pipe device continues growing, and the depletion layer between dielectric layer 3 adjacent at this time is to semiconductor substrate 1
Directional Extension is adjacent when backward voltage is greater than the voltage that the depletion layer between adjacent third dielectric layer 3c is born
Depletion layer between third dielectric layer 3c is exhausted by polysilicon 4, and reaching the second dielectric layer 3b in backward voltage can bear
Maximum voltage when, schottky diode device is breakdown, the maximum voltage be breakdown voltage.
Specifically, the thickness of dielectric layer 3 is bigger, polysilicon 4 gets over the voltage that exhausts of the drift region dielectric layer 3
Greatly, therefore, the drift region between the first dielectric layer 3a of thickness reduction by reducing the first dielectric layer 3a is consumed by polysilicon 4
Most voltage can make the just drift region between first stratum 3a of pinch off in a low voltage state of polysilicon 4, to shield gold
The interface for belonging to electrode layer 5 and epitaxial layer 2, reduces the electric field strength of interface, continues to increase to breakdown voltage in backward voltage
In the process, the electric field strength at metal electrode layer 5 and 2 interface of epitaxial layer is kept in a certain range, at this point, the second dielectric layer
The thickness of 3b and adjacent the distance between the second dielectric layer 3b determine the breakdown voltage of schottky diode device.
As a preferred embodiment in a kind of manufacturing method of schottky diode device provided by the invention, in step 6
Later, further include following step before step 7: to be formed with the 4th thickness the 4th is performed etching to the second dielectric layer 3b
Dielectric layer 3d, so that the 4th thickness of the 4th dielectric layer 3d is less than second thickness and is greater than first thickness, the 4th dielectric
Layer 3d between the first dielectric layer 3a and the second dielectric layer 3b and both ends respectively with the first dielectric layer 3a and second
Dielectric layer 3b contact, the 4th thickness of the 4th dielectric layer 3d along the second dielectric layer 3b to the first dielectric layer 3a's
It is gradually become smaller on direction.
Specifically, gradually increased by the first dielectric layer 3a to the dielectric layer thickness in the second direction dielectric layer 3b,
The voltage that exhausts for the drift region that the epitaxial layer 2 of adjacent dielectric interlayer is formed also gradually increases, and increases Schottky diode device
The stability of part, the thickness of the second dielectric layer 3b is maximum, so that the thickness of the second dielectric layer 3b and adjacent the
The width and thickness of epitaxial layer 2 between two dielectric layer 3b determine the breakdown voltage of schottky diode device, avoid
Schottky diode device is in backward voltage elevation process since metal electrode layer 5 and the electric-field strength at 2 interface of epitaxial layer are spent
It is high and cause punch through the problem of voltage reduces, leading for schottky diode device is reduced under conditions of not reducing breakdown voltage
Be powered pressure.
As a preferred embodiment in a kind of manufacturing method of schottky diode device provided by the invention, the first exposure mask
Plate is dura mater, and the ingredient of the dura mater is oxide and/or nitride.
As a preferred embodiment in a kind of manufacturing method of schottky diode device provided by the invention, the second electricity is situated between
Matter layer is silica.
As a preferred embodiment in a kind of manufacturing method of schottky diode device provided by the invention, described first
Dielectric layer is silicon nitride.
It include: to include: in schottky diode device in schottky diode device and manufacturing method provided by the invention
Semiconductor substrate 1 forms epitaxial layer 2 on semiconductor substrate 1；Epitaxial layer 2 offers multiple deep trouths, is formed in deep trouth inner wall
Dielectric layer 3, be formed in the polysilicon 4 in deep trouth and being located between the dielectric layer 3 on same deep trouth two sidewalls, formed
The metal electrode layer 5 on 2 surface of epitaxial layer between adjacent deep trouth, metal electrode layer 5 pass through contact hole and 4 phase of polysilicon
Even；Dielectric layer 3 includes the first dielectric layer 3a with first thickness and the second dielectric layer 3b with second thickness, and
One dielectric layer 3a is close to deep trouth opening direction, and the second dielectric layer 3b is close to the bottom of deep trouth, and first thickness is less than the second thickness
Degree.Make the top of schottky region at lower voltages to adjacent by using the first dielectric layer 3a of thinner thickness
The drift region of 3a is exhausted between one dielectric layer, formed a pinch-off voltage pinch off drift region shield metal electrode layer 5 with
Interface between epitaxial layer 2, so that the electric field strength between metal electrode layer 5 and epitaxial layer 2 is in backward voltage elevation process
In be kept low, avoid schottky diode device in backward voltage elevation process due to metal electrode layer 5 with
The electric field strength at 2 interface of epitaxial layer is excessively high and causes punch through the problem of voltage reduces, and drops under conditions of not reducing breakdown voltage
The low conducting voltage of schottky diode device.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
Claims (10)
1. a kind of schottky diode device characterized by comprising
Semiconductor substrate；
Form epitaxial layer on the semiconductor substrate, wherein the epitaxial layer offers multiple deep trouths；
It is formed in the dielectric layer of the deep trouth inner wall；
It is formed in the polysilicon in the deep trouth and being located between the dielectric layer；And
It is formed in the metal electrode layer of the epi-layer surface between the adjacent deep trouth, the metal electrode layer is by connecing
Contact hole is connected with the polysilicon；
Wherein, the dielectric layer includes at least the first dielectric layer with first thickness and the second electricity with second thickness
Dielectric layer, first dielectric layer is close to the deep trouth opening direction, and second dielectric layer is close to the bottom of the deep trouth
Portion, the first thickness are less than the second thickness.
2. schottky diode device as described in claim 1, which is characterized in that first dielectric layer is located at the depth
Above the side wall of slot, second dielectric layer is located at below the side wall of the deep trouth and the bottom of the deep trouth.
3. schottky diode device as claimed in claim 1 or 2, which is characterized in that the dielectric layer further includes having
The third dielectric layer of third thickness, the third thickness are greater than the first thickness and are less than the second thickness, and described the
Three dielectric layers are between first dielectric layer and second dielectric layer and both ends are electric with described first respectively
Dielectric layer and second dielectric layer contact.
4. schottky diode device as claimed in claim 1 or 2, which is characterized in that the dielectric layer further includes having
4th dielectric layer of the 4th thickness, the 4th dielectric layer are located at first dielectric layer and second dielectric layer
Between and both ends contacted respectively with first dielectric layer and second dielectric layer, the of the 4th dielectric layer
Four thickness are gradually becoming smaller along second dielectric layer on the direction of first dielectric layer.
5. schottky diode device as claimed in claim 1 or 2, which is characterized in that the dielectric layer is silica.
6. a kind of manufacturing method of schottky diode device, which comprises the following steps:
Step 1: on a semiconductor substrate by being epitaxially-formed epitaxial layer；
Step 2: depositing the first exposure mask on said epitaxial layer there；
Step 3: carrying out deep etching to the epitaxial layer, it is deposited with the position other than first exposure mask on said epitaxial layer there
It sets and performs etching to form deep trouth；
Step 4: removal first exposure mask, forms dielectric layer in the epi-layer surface；
Step 5: the deposit polycrystalline silicon in the deep trouth for being formed with the dielectric layer, and the polysilicon is performed etching to be formed
First groove, the first groove have the first depth；
Step 6: performing etching the part in the dielectric layer close to the deep trouth opening direction so that the dielectric layer
Including the first dielectric layer with first thickness and the second dielectric layer with second thickness, first dielectric layer is leaned on
The nearly deep trouth opening direction, for second dielectric layer close to the bottom of the deep trouth, the first thickness is less than described the
Two thickness；
Step 7: making between the surface of the polysilicon and the adjacent deep trouth in deposit polycrystalline silicon in the first groove
Epi-layer surface flush.
Step 8: the epi-layer surface between the adjacent deep trouth forms metal electrode layer, the metal electrode layer and institute
Polysilicon is stated to be connected.
7. manufacturing method as claimed in claim 6, which is characterized in that after the step 6, before the step 7 also
Include the following steps:
Second dielectric layer is performed etching to form the third dielectric layer with third thickness, so that the third thickness
Greater than the first thickness and be less than the second thickness, the third dielectric layer be located at first dielectric layer with it is described
Between second dielectric layer and both ends are contacted with first dielectric layer and second dielectric layer respectively.
8. manufacturing method as claimed in claim 6, which is characterized in that after the step 6, before the step 7 also
Include the following steps:
Second dielectric layer is performed etching to form the 4th dielectric layer with the 4th thickness, so that the 4th electricity is situated between
4th thickness of matter layer is less than the second thickness and is greater than the first thickness, and the 4th dielectric layer is located at described first
Between dielectric layer and second dielectric layer and both ends respectively with first dielectric layer and second dielectric
Layer contact, the 4th thickness of the 4th dielectric layer along second dielectric layer to the side of first dielectric layer
It gradually becomes smaller upwards.
9. manufacturing method as claimed in claim 6, which is characterized in that first mask plate be dura mater, the dura mater at
It is divided into oxide and/or nitride.
10. manufacturing method as claimed in claim 6, which is characterized in that the dielectric layer is silica.
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| WO2022198723A1 (en) * | 2021-03-26 | 2022-09-29 | 光华临港工程应用技术研发(上海)有限公司 | Schottky diode manufacturing method |
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