CN207868205U - A kind of silicon carbide diode device - Google Patents

Abstract

The utility model provides a kind of silicon carbide diode device, and structure cell includes：Anode metal, p-type epitaxial layer, n-type drift layer, n+ substrates and cathodic metal are arranged with this from top to bottom, contact groove is equipped at the top of the p-type epitaxial layer, the anode metal bottom is equipped with protrusion, the contact groove is mutually matched with the protrusion, it solves in junction barrier schottky diode, due to the presence in pn-junction region, it is smaller that area is effectively connected in device under conducting state, leads to the higher problem of conducting resistance.

Description

A kind of silicon carbide diode device

Technical field

The utility model is related to a kind of silicon carbide diode devices.

Background technology

Silicon carbide is a kind of emerging third generation semi-conducting material, has good physical characteristic and electrology characteristic, wide It is used to prepare high-power and high temperature Flouride-resistani acid phesphatase electronic device generally.SiC schottky diode is that earliest realize is commercialized Sic semiconductor device, common commercialization Schottky diode be Schottky-barrier diode (Schottky Barrier Diodes) and junction barrier schottky diode (Junction Barrier Schottky Diodes).

Traditional junction barrier schottky diode is that SBD structures are born reversely partially using the space-charge region of reverse biased pn junction Pressure, so as to which on the basis of ensureing blocking voltage, the appropriate schottky barrier height that reduces is subtracted simultaneously with reducing forward voltage drop The small reverse-biased electric leakage of diode.However, due in junction barrier schottky diode, ion implanting tie region can not be conductive, Therefore effective conducting area of device reduces, this disadvantage limits further increasing for JBS break-over of device current densities.

Invention content

The technical problems to be solved in the utility model is to provide a kind of silicon carbide diode device, solves junction barrier Xiao In special based diode, due to the presence in pn-junction region, it is smaller that area is effectively connected in device under conducting state, cause conducting resistance compared with High problem.

The utility model is realized in this way：A kind of silicon carbide diode device, structure cell include：From top to bottom with This setting anode metal, p-type epitaxial layer, n-type drift layer, n+ substrates and cathodic metal, the p-type epitaxial layer top, which is equipped with, to be connect Slot is touched, the anode metal bottom is equipped with protrusion, and the contact groove is mutually matched with the protrusion.

Further, the doping concentration of the n-type drift layer ranging from 2 × 10¹⁴cm^-3To 1 × 10¹⁶cm^-3, the N-shaped drift The thickness for moving layer is 5um to 200um.

Further, the doping concentration of the p-type epitaxial layer is more than or equal to 1 × 10¹⁹cm^-3。

Further, the thickness of the p-type epitaxial layer is 0.2um to 1um, and the width of the contact groove is 4um to 16um, The contact trench bottom to n-type drift layer distance from top is less than or equal to 5nm.

Further, the anode metal is Ni or Ti, and the cathodic metal is Ni.

Further, the width 14um to 46um of the anode metal.

The utility model has the advantage of：A kind of silicon carbide diode device of the utility model, can be applied to extensive electricity Range is pressed, there is good on state characteristic and reverse recovery characteristic.The preparation process of the structure and conventional silicon carbide diode device Part is compatible with, due in the case of identity unit area, having the current lead-through area of bigger；

Also, the utility model introduces highly doped p-type anode region, device is made to exist on the basis of conventional SBD device When forward conduction, carrier can pass through p-type area by tunneling effect；Under reverse blocking state, extension pn-junction is born instead To bias, reverse biased is born compared to SBD and JBS devices use schottky junctions, which bears reverse-biased electricity using pn-junction Pressure, can reduce the leakage current under blocking state.

Description of the drawings

The utility model is further described in conjunction with the embodiments with reference to the accompanying drawings.

Fig. 1 is the silicon carbide diode device cellular structural schematic diagram of the utility model embodiment.

Fig. 2 is the step flow chart of the utility model embodiment.

Contact groove is formed in a kind of manufacturing method for silicon carbide diode device that Fig. 3 provides for the utility model embodiment Schematic diagram one.

Contact groove is formed in a kind of manufacturing method for silicon carbide diode device that Fig. 4 provides for the utility model embodiment Schematic diagram two.

Contact groove is formed in a kind of manufacturing method for silicon carbide diode device that Fig. 5 provides for the utility model embodiment Schematic diagram three.

Contact groove is formed in a kind of manufacturing method for silicon carbide diode device that Fig. 6 provides for the utility model embodiment Schematic diagram four.

Contact groove is formed in a kind of manufacturing method for silicon carbide diode device that Fig. 7 provides for the utility model embodiment Step flow chart.

Specific implementation mode

Refering to Figure 1, the utility model silicon carbide diode device, is formed by multiple structure cell parallel connections , which includes：From top to bottom with this be arranged anode metal 4, p-type epitaxial layer 3, n-type drift layer 2, n+ substrates 1 and Cathodic metal 5,3 top of the p-type epitaxial layer are equipped with contact groove, and 4 bottom of the anode metal is equipped with protrusion, the contact groove It is mutually matched with the protrusion, the doping concentration ranging from 2 × 10 of the n-type drift layer 2¹⁴cm^-3To 1 × 10¹⁶cm^-3, described The thickness of n-type drift layer 2 is 5um to 200um, and the doping concentration of the p-type epitaxial layer 3 is more than or equal to 1 × 10¹⁹cm^-3, the p The thickness of type epitaxial layer 3 is 0.2um to 1um, and the width of the contact groove is 4um to 16um, and the contact trench bottom to N-shaped floats It moves 2 distance from top of layer and is less than or equal to 5nm, the anode metal 4 is Ni or Ti, and the cathodic metal 5 is Ni, the anode metal 4 width 14um to 46um；By change p-type epitaxial layer 3 thickness, the width and depth of doping concentration and central contact slot, It can be made preferably between conducting resistance and blocking electric leakage.

The anode metal 4 selects Ni/Ti, it is therefore an objective to form positive contact, field plate knot is formed while filling contact groove The length of structure, field plate is 5um to 15um, it is therefore an objective to which the electric field for reducing device cellular edge is concentrated.The cathodic metal 5 selects Ni, it is therefore an objective to form cathode ohmic contact.

As shown in Fig. 2, the preparation method of the utility model silicon carbide diode device, specifically comprises the following steps：

Pass through epitaxial growth n-type drift layer 2 on n+ substrates 1；

Pass through epitaxial growth p-type epitaxial layer 3 in the n-type drift layer 2；

Contact groove is formed by etching in the p-type epitaxial layer 3；

Metal is deposited by electron beam evaporation or magnetically controlled sputter method, and carries out contact annealing, forms cathodic metal 5；

Metal is deposited by electron beam evaporation or magnetically controlled sputter method, is lithographically formed anode metal 4.

It is described to form contact groove by etching in the p-type epitaxial layer 3 further and be specially：

On p-type epitaxial layer surface by the method for electron beam evaporation, evaporation forms the W metal that thickness is 0.3um and is used as quarter Mask material is lost, photoetching trepanning is carried out to the mask material, RIE is etched away the required W metal outputed on contact groove Mask layer；

Preparation is identical with p-type epitaxial thickness to accompany piece, is hung down using ICP dry etchings to matching piece and p-type epitaxial layer Straight etching, is etched to and stops after 50nm at the top of p-type epitaxial layer；

Using concentrated sulfuric acid dioxygen water mixed liquid, remove the metal on surface under heating condition；

To accompanying piece to carry out SEM observations, residue p-type epitaxial layer thickness is determined, and oxygen is calculated in conjunction with Deal-Grove models The time required to changing residue 5nm thickness p-type epitaxial layer；

To p-type epitaxial layer according to oxidation one oxide layer of formation is carried out the time required to calculating, remove oxidation using BOE solution Layer, ultimately forms the contact groove.

It is described that cathodic metal 5 is deposited by electron beam evaporation or magnetron sputtering, and carry out contact annealing and be specially further： In the one side of n+ substrates 1, W metal is deposited using electron beam evaporation method or magnetron sputtering shallow lake method, under the protection of nitrogen, Contact annealing, annealing time 2min are carried out, annealing temperature is 975 DEG C, and the thickness of deposit metal can be controlled according to user demand Degree.

It is described that metal is deposited by electron beam evaporation or magnetically controlled sputter method, it is further specific to be lithographically formed anode metal 4 For：Using electron beam evaporation method or magnetron sputtering shallow lake method deposit 200nm W metals or Ti, contacted under nitrogen protection Annealing, annealing time 2min, annealing temperature are 500 DEG C, and the thickness of deposit metal can be controlled according to user demand.

The utility model embodiment one

The preparation method of the utility model silicon carbide diode device, the method includes：

S1, pass through epitaxial growth n-type drift layer 2 on n+ substrates 1；

S2, in the n-type drift layer 2 by p-type epitaxial layer 3 that epitaxial growth is highly doped；

S3, in the p-type epitaxial layer 3, by etching form contact groove；

S4, at the device back side, cathodic metal 5 is deposited by electron beam evaporation or magnetron sputtering, and carry out contact annealing；

S5, field plate figure is lithographically formed by electron beam evaporation or magnetron sputtering deposit anode metal 4 in device front.

Step S3 shown in it needs to form contact groove, 2 top 5nm of distance from bottom n-type drift layer by lithographic method Hereinafter, the utility model provides a kind of method feasible under the conditions of prior art.

As shown in Fig. 3 to Fig. 7, first, in wafer surface by the method for electron beam evaporation, evaporation forms thickness and is The W metal of 0.3um carries out photoetching trepanning as etch mask layer material, to the mask material, and RIE is etched away contact groove On W metal mask layer.The SiC for preparing identical epitaxial structure later accompanies piece, and using ICP dry etchings, to main leaf, (main leaf is For the p-type epitaxial layer made by the utility model) and accompany piece (be and p-type epitaxial layer structure and the SiC being of uniform thickness, use In process certification) vertical etch is carried out, it is etched to and stops after 3 top about 50nm of p-type epitaxial layer.It is double followed by the concentrated sulfuric acid Oxygen water mixed liquid removes the metal on surface under heating condition.Then, it accompanies piece to carry out SEM observations etching, determines outside residue p-type Prolong 3 thickness of layer, and 3 required time of oxidation residue 5nmp types epitaxial layer is calculated in conjunction with Deal-Grove models.Finally, to main leaf Oxidation, which is carried out, according to design conditions forms SiO₂Oxide layer 6 removes SiO using BOE solution₂Oxide layer 6 ultimately forms described connect Touch slot.

The step S4, using W metal as cathode ohmic contact material, process includes：Wafer is overturn, is served as a contrast in (1) n+ The back side at bottom 1 carries out contact annealing using the method deposition 200nm W metals of electron beam evaporation under the protection of N2 gases 2min, 975 DEG C of annealing temperature.

The step S5 is needed using anode metal 4Ti/Ni filling contact grooves, including：At the back side of wafer, spin coating is simultaneously Post bake protects the established Ohmic contact in the back side.Wafer is overturn later, utilizes the method deposited metal Ti/Ni of electron beam evaporation. After spin coating, photoetching, development and post bake, etching metal forms field plate structure.Later under the protection of N2 gases, schottky junctions are carried out Touch annealing 2min, 500 DEG C of annealing temperature.

Although the foregoing describe specific embodiment of the present utility model, those familiar with the art answers Working as understanding, we are merely exemplary described specific embodiment, rather than for the limit to the scope of the utility model Fixed, those skilled in the art modification and variation equivalent made by the spirit according to the utility model all should Cover in the scope of the claimed protection of the utility model.

Claims (6)

1. a kind of silicon carbide diode device, it is characterised in that：Its structure cell includes：Anode gold is arranged with this from top to bottom Category, p-type epitaxial layer, n-type drift layer, n+ substrates and cathodic metal, the p-type epitaxial layer top are equipped with contact groove, the sun Pole metal bottom is equipped with protrusion, and the contact groove is mutually matched with the protrusion.

2. a kind of silicon carbide diode device as described in claim 1, it is characterised in that：The doping of the n-type drift layer is dense Degree ranging from 2 × 10¹⁴cm^-3To 1 × 10¹⁶cm^-3, the thickness of the n-type drift layer is 5um to 200um.

3. a kind of silicon carbide diode device as described in claim 1, it is characterised in that：The doping of the p-type epitaxial layer is dense Degree is more than or equal to 1 × 10¹⁹cm^-3。

4. a kind of silicon carbide diode device as described in claim 1 or 3, it is characterised in that：The thickness of the p-type epitaxial layer Width for 0.2um to 1um, the contact groove is 4um to 16um, and the contact trench bottom is small to n-type drift layer distance from top In equal to 5nm.

5. a kind of silicon carbide diode device as described in claim 1, it is characterised in that：The anode metal is Ni or Ti, The cathodic metal is Ni.

6. a kind of silicon carbide diode device as described in claim 1, it is characterised in that：The width 14um of the anode metal To 46um.