阅读说明：本技术 高压碳化硅肖特基二极管倒装芯片阵列 (High pressure carbonization silicon Schotty diode flip chip array ) 是由 丘树坚 王兆伟 于 2019-01-16 设计创作，主要内容包括：一种碳化硅二极管,其包含碳化硅衬底(20)、位于碳化硅衬底顶部的碳化硅层(24)、设置在碳化硅层上并沿着碳化硅层顶表面彼此分离两个第一低势垒金属部分(36)、连接到两个低势垒金属部分的第一高势垒金属部分(30)。碳化硅层比碳化硅衬底更薄并且具有更低的掺杂。第一高势垒金属部分位于碳化硅层上的沿着碳化硅层顶表面方向的两个第一低势垒金属部分之间。通过减小结势垒处的漏电流,碳化硅二极管的反向击穿电压显著提高。(A kind of silicon carbide diode, the first high barrier metal part (30) that silicon carbide layer (24), setting it includes silicon carbide substrates (20), at the top of silicon carbide substrates are separated from each other two the first low barrier metal parts (36) on the silicon carbide layer and along silicon carbide layer top surface, are connected to two low barrier metal parts.Silicon carbide layer is thinner than silicon carbide substrates and has lower doping.First high barrier metal part is located between two the first low barrier metal parts along silicon carbide layer top surface direction on silicon carbide layer.By reducing the leakage current at junction barrier, the breakdown reverse voltage of silicon carbide diode is significantly improved.)

1. a kind of silicon carbide diode, comprising:

A) silicon carbide substrates；

B) silicon carbide layer at the top of silicon carbide substrates, the silicon carbide layer is thinner than the silicon carbide substrates and has lower Doping；

C) two the first low barrier metal parts are arranged on the silicon carbide layer, and along the silicon carbide layer top surface It is separated from each other；

D) the first high barrier metal part is connected to described two low barrier metal parts；

Wherein, the described first high barrier metal part is located on the silicon carbide layer along the direction of the silicon carbide layer top surface Between two the first low barrier metal parts.

2. silicon carbide diode according to claim 1 further includes the second high barrier metal part；Described first and second High barrier metal part barrier metal low with described two first part is set on the silicon carbide layer top surface in an alternating manner It sets, so that the first high barrier metal part and the second high barrier metal part are separated by a first low barrier metal part It opens.

3. silicon carbide diode according to claim 2, wherein the first high barrier metal part and described second high Barrier metal part further extends downwardly in the silicon carbide layer to form two first grooves.

4. silicon carbide diode according to claim 3 further includes the second low potential barrier positioned at the first groove bottom Metal part.

5. silicon carbide diode according to claim 1 further includes a high barrier metal cap, with the silicon carbide layer one It rises, encapsulates the described first low barrier metal part completely.

6. silicon carbide diode according to claim 1, wherein the first high barrier metal part is further to downward It reaches in the silicon carbide layer to form first groove.

7. silicon carbide diode according to claim 1 further includes and the active second groove distinguished, the active area It is determined by the described first high barrier metal part and described two first low barrier metal parts；The second groove is by dielectric material Material is formed.

8. silicon carbide diode according to claim 7 further includes multiple second grooves, multiple second grooves It is separated from each other；When viewed from above each second groove formed one it is close-shaped.

9. silicon carbide diode according to claim 8, the plurality of second groove forms multiple concentric rings.

10. silicon carbide diode according to claim 8, the plurality of second groove passes through one or more thirds High barrier metal part is separated from each other.

11. silicon carbide diode according to claim 7 further includes aluminium compound buffer layer, it is located at second ditch Interface between slot and the silicon carbide layer.

12. a kind of silicon carbide diode, comprising:

A) silicon carbide substrates；

B) silicon carbide layer at the top of the silicon carbide substrates, the silicon carbide layer is thinner than the silicon carbide substrates and has Lower doping；

C) active area determined by at least one barrier metal formed on the silicon carbide layer；With

D) the multiple grooves formed inside the silicon carbide layer, the multiple groove along the silicon carbide layer top surface side It is separated to the active region；

When viewed from above wherein each groove formed one it is close-shaped；Each groove is formed by dielectric material； With

E) the multiple barrier metals formed on the silicon carbide layer outside the active area；Wherein each barrier metal forms one A close-shaped, each barrier metal is located between two grooves in the multiple groove when viewed from above.

13. silicon carbide diode according to claim 12 further includes aluminium compound buffer layer, it is located at second ditch Interface between slot and the silicon carbide layer.

14. a kind of method for making silicon carbide diode, comprising the following steps:

A) one silicon carbide layer is provided at the top of silicon carbide substrates；The silicon carbide layer is thinner than the silicon carbide substrates and has Lower doping；

B) first groove and second groove are formed in the silicon carbide layer；The first groove is the silicon carbide diode A part of active area；The second groove is separated with the first groove；

C) low barrier metal is deposited on the top surface of silicon carbide layer in the active area, covers the first groove；With

D) high barrier metal is deposited on the top surface of silicon carbide layer in the active area, covers the first groove.

15. according to the method for claim 14, wherein step b) further include: form multiple second grooves, the multiple the Two grooves are separated and are separated from each other with the first groove, and it is close-shaped that each second groove forms one.

16. according to the method for claim 15, wherein step d) further include: around the multiple second groove opening The high barrier metal is deposited on partially carbonized silicon layer.

17. according to the method for claim 14, wherein step b) further include: form multiple first grooves, the multiple the One groove is separated with the second groove, and is separated from each other by least part silicon carbide layer.

18. according to the method for claim 14, wherein step c) further include: deposit institute on the first groove bottom surface Low barrier metal is stated, and deposits the low barrier metal on the parameatal partially carbonized silicon layer of the first groove.

19. according to the method for claim 14, further includes: fill the first groove with the high barrier metal.

20. according to the method for claim 14, further includes: fill the second groove with dielectric material.

21. according to the method for claim 20, further includes: the interface between the second groove and the silicon carbide layer Form buffer layer.

[technical field]

The present invention relates to semiconductor devices, in particular to silicon carbide diode.

[background technique]

Silicon carbide (SiC) device belongs to so-called wide band gap semiconducter group, and compared with common silicon (Si), they are high pressure Power semiconductor provides many attractive characteristics.In particular, the breakdown field intensity and thermal conductivity of SiC want much higher, this So that they are most important to power electronic system.These diodes, which have, is made the comparable static properties of diode with silicon.This Outside, the Schottky diode based on silicon carbide not will receive the influence of switching loss.

But existing silicon carbide diode frequently encounters other problems, including but not limited to big leakage current and low Breakdown reverse voltage, this can be such that the performance of silicon carbide diode deteriorates.If diode leakage current is very high, blocking voltage (blocking voltage) can be very low.Therefore, for higher blocking voltage application, leakage current is needed to be improved.

[summary of the invention]

In view of foregoing background, the object of the present invention is to provide a kind of silicon carbide diode array of substitution, eliminate or extremely Above-mentioned technical problem is alleviated less.

Above-mentioned purpose is met by the feature combination of primary claim；Dependent claims also disclose of the invention Other advantageous embodiments.

Those skilled in the art will obtain other objects of the present invention from being described below.Therefore, above-mentioned purpose, which is stated, is not Some purposes that are exhaustive, being merely to illustrate in many purposes of the invention.

Therefore, on the one hand, the present invention is silicon carbide diode, at the top of silicon carbide substrates, silicon carbide substrates Silicon carbide layer, setting on the silicon carbide layer two the first low barrier metal parts (divide each other along silicon carbide layer top surface From) and be connected to the first high barrier metal part of two low barrier metal parts.Silicon carbide layer is thinner than silicon carbide substrates And there is lower doping.First high barrier metal part is located on silicon carbide layer along the direction of silicon carbide layer top surface Between two the first low barrier metal parts.

Preferably, silicon carbide diode further includes the second high barrier metal part.First and second high barrier metal parts It is configured with two the first low barrier metal parts at silicon carbide layer top surface with alternation method, so that the first high barrier metal portion Divide and the second high barrier metal part is separated by one of them first low barrier metal part.

It is highly preferred that the first high barrier metal part and the second high barrier metal part are extended further down into silicon carbide To form two first grooves in layer.

Most preferably, silicon carbide diode also includes positioned at the second low barrier metal part of first groove bottom.

According to preferred embodiment change case, silicon carbide diode also includes one high barrier metal cap, with carbon SiClx layer encapsulates the first low barrier metal part completely together.

According to another change case of preferred embodiment, the first high barrier metal part is extended further down into silicon carbide layer In to form first groove.

According to being further variations on for preferred embodiment, silicon carbide diode further includes and active the second ditch distinguished Slot, active area are determined by the first high barrier metal part and two the first low barrier metal parts.Second groove is by dielectric material It is formed.

Preferably, silicon carbide diode also includes multiple second grooves separated from each other.When viewed from above, Mei Ge Two grooves formation one is close-shaped.

It is highly preferred that multiple second grooves form multiple concentric rings.

According to being further variations on for preferred embodiment, multiple second grooves are by the high barrier metal portion of one or more thirds Divide and is separated from each other.

According to being further variations on for preferred embodiment, silicon carbide diode also includes aluminium compound buffer layer, as An interface between two grooves and silicon carbide layer.

According to another aspect of the present invention, a kind of silicon carbide diode is disclosed, it includes silicon carbide substrates, is located at carbonization Silicon carbide layer at the top of silicon substrate, is formed in silicon carbide at the active region determined by barrier metal at least one on silicon carbide layer Multiple grooves inside layer, multiple grooves are separated along the direction of silicon carbide layer top surface with active region.Silicon carbide layer compares carbon Silicon substrate is thinner and has lower doping.When viewed from above, each groove forms a closed shape；Each Groove is formed by dielectric material.Multiple barrier metals are also formed on silicon carbide layer outside active area；When viewed from above, Wherein it is close-shaped to form one for each barrier metal, and is located between two grooves.

Preferably, silicon carbide diode also includes aluminium compound buffer layer, between second groove and silicon carbide layer Interface.

According to another aspect of the present invention, a kind of method for making silicon carbide diode is disclosed.This method includes following Step: providing a silicon carbide layer on the top of silicon carbide substrates, and first groove and second groove are formed inside silicon carbide layer, Low barrier metal is deposited on the silicon carbide layer top surface in active area, first groove is covered, deposits high barrier metal active On silicon carbide layer top surface in area, first groove is covered.First groove is a part of the active area of silicon carbide diode. Second groove is separated with first groove.Silicon carbide layer is thinner than silicon carbide substrates and has lower doping.

Preferably, above-mentioned forming step further include: form multiple second grooves, the multiple second groove and first groove It separates and is separated from each other, each described second groove formation one close-shaped.

It is highly preferred that the step of above-mentioned deposition high barrier metal further include: in the carbon of the opening around multiple second grooves The high barrier metal of SiClx layer deposited on portions.

According to preferred embodiment change case, the step of forming first groove and second groove further include: formed more A first groove, the multiple first groove are separated with second groove, and by least part silicon carbide layer, the multiple First groove is separated from each other.

According to another change case of preferred embodiment, the step of depositing low barrier metal further include: in first groove Low barrier metal is deposited on bottom surface and on the parameatal partially carbonized silicon layer of first groove.

According to being further variations on for preferred embodiment, this method further include: fill first groove with high barrier metal.

According to being further variations on for preferred embodiment, this method further include: fill second groove with dielectric material.

According to being further variations on for preferred embodiment, this method further include: in the boundary of second groove and silicon carbide layer A buffer layer is formed at face.

Therefore, it can be seen that silicon carbide diode of the present invention includes many innovations variation to semiconductor structure, Mei Gebian Change and both contributes to reduce the leakage current at junction barrier.When these innovation variations are combined together, compared with traditional devices, gained To silicon carbide diode there is the leakage current that may be significantly smaller, to realize higher blocking voltage.For example, in silicon carbide layer Form groove and simultaneously fill them with dielectric material, reduce electric field and leakage current at junction barrier, but add a buffer layer into One step alleviates current leakage.Similarly, multiple grooves are formed in active region, forms multiple mixing Xiao Te in active area Base groove both contributes to reduce the leakage current at junction barrier.It is realized although should be noted that using the configuration in most preferred embodiment Optimum performance, but can be in any combination thereof freely using innovation variation.

Further it is proposed that the production method of silicon carbide diode be advantageous, not only due to and traditional handicraft It is reduced compared to cost, and more importantly deposits the technology and tight termination filling skill of trench metal in a self-aligned manner Art, helping to realize reduces leakage current and high-breakdown-voltage, while keeping relatively low manufacturing cost.In contrast, it is passing It is higher for realizing the ion implanting cost of metalloid deposition effect in system technology.

[Detailed description of the invention]

From the description of preferred embodiment below, aforementioned and further feature of the invention be will become obvious, described Preferred embodiment is only provided in conjunction with attached drawing by way of example, in which:

Fig. 1 is the schematic cross-section of the silicon carbide diode of first embodiment of the invention.

Fig. 2 a is the attached view of the layout of the silicon carbide diode of Fig. 1, it is shown that second groove and high barrier metal.

Fig. 2 b is the attached view of simplification of the silicon carbide diode of Fig. 1, only shows the layout of barrier metal.

Fig. 3 a is shown uses SiO respectively₂As passivation and Al₂O₃The reverse breakdown of silicon carbide diode as passivation The comparison of the experimental result of voltage.

Fig. 3 b is shown uses SiO respectively₂As passivation and Al₂O₃The leakage current of silicon carbide diode as passivation The comparison of experimental result.

Fig. 4 is the diagram of leakage current flow in the active area of the silicon carbide diode of Fig. 1-2 b.

Fig. 5 a-5j shows a kind of method and step that can be used to form the silicon carbide diode array of Fig. 1.

Fig. 6 a-6d shows the cross sectional view of the silicon carbide diode of some other embodiments of the present invention.

In the accompanying drawings, in several embodiments described herein, the identical component of identical digital representation.

[specific embodiment]

In the description of the present invention and in appended claims, in addition to due to Explicit Language or necessary meaning and context is wanted Except asking, word " include " or " contain " is used for inclusiveness meaning, i.e., the presence of the clearly described feature, but is not precluded within the present invention There is or add other features in various embodiments.

As used herein and in the claims, unless otherwise stated, " coupling " or " connection " refers to by one A or multiple electric devices are directly or indirectly electrically coupled or connect.

The term of such as "horizontal" used herein, " vertical ", " upward ", downwards ", " top ", " lower section " etc is The purpose of the present invention is described in normal use direction.It is not intended to limit the invention to any specific direction.

Referring now to Fig. 1-2 b, the first embodiment of the present invention is the silicon carbide diode of Schottky type, and it includes carbonizations Fabric of the silicon substrate 20 as device.As the skilled person will understand that, silicon carbide substrates 20 are made of SiC wafer, carbonization Silicon substrate 20 is n+ type.At the top of silicon carbide substrates 20, there are one layer of N-shaped silicon carbide epitaxial layers 24.Silicon carbide layer 24 is than carbonization Silicon substrate 20 is thinner and has lower doping.

In silicon carbide substrates 20 in the following, the cathode for thering is one layer of ohmic metal layer 28 to form silicon carbide diode.In the other side, In the central area of device, there are also the sun that junction barrier metal (junction barrier metals) forms silicon carbide diode Pole.Particularly, in this embodiment, two distinct types of barrier metal (barrier metal), including high barrier metal and Low barrier metal forms the mixing schottky metal of silicon carbide diode.As shown in Figure 1, in vertically extending entire silicon carbide Near the central axis 21 of diode, at least there are two first grooves 26, respectively by the first high barrier metal part 30 and second High barrier metal part 32 forms (part surrounded as shown in the figure by two parallel dotted lines), extends downwardly into silicon carbide layer 24 In.In other words, first groove 26 is filled with high barrier metal.Two first grooves 26 are preferably of the same size.In The bottom of each first groove 26 is disposed with the second low barrier metal part 34, substantially has the shape of bar shaped.Second is low Barrier metal part 34 also separates (as shown in Figure 4) with the side wall 26a of first groove 26.In addition, surrounding two first grooves On the top surface of 26 silicon carbide layer 24, there are the multiple first low potential barrier gold on a direction along the top surface of silicon carbide layer 24 Belong to part 36.In Fig. 1, there are three the such first low barrier metal parts 36, they are separated from each other.Each first low potential barrier The width of metal part 36 and the width of first groove 26 are essentially identical, and the width is greater than the depth of first groove 26.It is special It is not that between the every two adjacent first low barrier metal part 36, there are also the first high barrier metal part 30 or the second is high Barrier metal part 32.Therefore, the first high barrier metal part 30 and the second high barrier metal part 32 gesture low with multiple first Base metal part 36 configures in an alternating manner, they are placed along same horizontal line (not shown).Note that the first low barrier metal portion 36 are divided all to deviate the second low barrier metal part 34 in the vertical direction and the horizontal direction.

In addition, there is a higher barrier metal lid 22 to be formed in the first high barrier metal part 30, the second high potential barrier gold On the top for belonging to part 32 and multiple first low barrier metal parts 36.The first high gesture is sealed in lid 22 and silicon carbide layer 24 completely Base metal part 30, the second high barrier metal part 32 and multiple first low barrier metal parts 36.In addition, although using different Unit number the embodiment described, but higher barrier metal lid 22, the first high barrier metal part 30, the second high gesture Base metal part 32 and two first grooves 24 are all made of identical high barrier metal, therefore they are formed together a monolith Material.Different unit numbers is only used for should be readily appreciated that the geometry of the Schottky barrier metal of silicon carbide diode.First High barrier metal part 30, the second first groove 36 of high barrier metal part 32, two (have the second low barrier metal part 34) active region of silicon carbide diode is formed together with the multiple first low barrier metal parts 36.

Higher barrier metal and lower barrier metal can be the metal of any suitable type, with silicon carbide layer 24 and carbon Silicon substrate 20 forms a schottky junction.The example of these materials includes titanium (Ti), nickel (Ni), titanium nitride (TiN), titanium aluminium (TiAl), platinum (Pt) etc..But since their ordinary meaning shows that high barrier metal should generate ratio in silicon carbide diode The low stronger junction barrier of barrier metal.

Except active region, multiple second grooves 38 are formed in silicon carbide layer 24, each filling of second groove 38 is situated between Electric material (not shown in figure 1).In Fig. 1, the quantity of the second groove 38 of active area two sides is identical, and second groove 38 is surrounded with Source region is arranged symmetrically.Similar to above-mentioned first groove 36, second groove 38 is extended downwardly from the top surface of silicon carbide layer 24.Second The depth of groove 38 and first groove 36 is essentially identical.However, it is possible to find out, along the level side of the top surface of silicon carbide layer 24 There is different width to, different second groove 38, compared with far from those of active area second groove 38, closer to active Those of area second groove 38 has smaller width.In silicon carbide layer 24, each second groove 38 is surrounded, in second groove There is a buffer layer 40 in interface between 38 and silicon carbide layer 24.Buffer layer 40 is by aluminum contained compound (such as aluminium oxide Al₂O₃Or Aluminium nitride AlN) it is made.In addition, adjacent second groove 38 is separated from each other by third higher barrier metal part 42.Multiple Three higher barrier metal parts 42 are deposited on the top surface of silicon carbide layer 24, and along with the first high barrier metal part 30, the identical horizontal line in the second high barrier metal part 32 and multiple first low barrier metal parts 36.

Note that first groove 26 is shown as separated part in Fig. 1, but this is because Fig. 1 is cutting for diode structure Face figure.Two first grooves 26 are actually close-shaped, year colyliform especially as shown in figures 2 a and 2b.When along vertical flat When silicon carbide diode is observed in any cross section in face, obtained view all with it is same or similar in Fig. 1.Similar to first Groove 26, from the top of silicon carbide diode, the second low potential barrier gear metal part 34 is also a monocycle, such as Fig. 2 a and 2b It is shown.Similarly, from the top of silicon carbide diode, the symmetrical any two second groove 38 of active area is surrounded in Fig. 1 It is also monocycle, as shown in figures 2 a and 2b.Fig. 2 a and 2b are clearly shown that in this embodiment, there are five close-shaped second Groove 38, and especially year colyliform.These annual rings are concentric.The annual ring of first groove 26 is (by the first high barrier metal portion Point 30/ second high barrier metal part 32 indicates) it is also concentric with those of second groove 38 ring.

By implementing above structure, the breakdown reverse voltage of the silicon carbide diode in the present embodiment has obtained particularly changing It is kind.Compared with traditional voltage rating is the SiC diode of 600V, it is big that above-mentioned silicon carbide diode can achieve reduction leakage current In 40%, blocking voltage, which improves, is greater than 38%, but manufacturing cost reduces 44.2%.The realization of these technical effects is by upper State the combination of each character of innovation, including but not limited to the first and second grooves, lower barrier metal and higher barrier metal Combination, the low barrier metal part of vertical shift, around higher barrier metal part and second groove between second groove Buffer layer.It should be understood, however, that each individually feature can be used alone or with its in other modifications of the invention He is limitedly applied in combination feature, to realize some effects, although not being optimal.It is explained below by more above-mentioned The performance improvement that Individual features generate.

Firstly, the mixing Schottky junction structure in the silicon carbide diode of Fig. 1-2 b includes higher barrier metal and lower potential barrier Metal realizes good balance between blocking voltage (reverse biased) and conducting voltage (forward bias).High potential barrier gold Belong to end and help to realize high blocking voltage, low barrier metal active area helps to realize high forward current.Obviously, it is important that same The high forward current and high blocking voltage that Shi Shixian diode current flow state works normally, to avoid diode in reverse bias Breakdown.In the silicon carbide diode of Fig. 1-2, higher barrier metal cap 22 provides terminal in the boundary of active area, therefore can Electric field is crowded to efficiently reduce, to reduce the leakage current at terminal.On the other hand, the low barrier metal deposition of different piece In active area, this helps to provide high forward current for Schottky diode.

The arrangement of second groove 38 outside active region with dielectric material additionally aids crowded by reducing electric field To reduce leakage current.If leakage current is easier the Schottky entered in active area from silicon carbide layer 24 without second groove 38 Metal.There is second groove 38, because of the dielectric material filled in second groove 38, there is resistivity increment (for example, size It is 10¹⁵Ohm), cause leakage current to reduce.Therefore, there are less electric fields to gather around at the terminal of the active area of silicon carbide diode It squeezes.

In silicon carbide diode above, there is the ring of multiple second grooves 38, This further reduces active area terminals The electric field at place is crowded.Compared with the configuration of only one second groove 38, multiple second grooves 38 can achieve electric field strength drop Low at least 61%.

In addition, the buffer layer 40 around each second groove 38 in above-mentioned silicon carbide diode further reduces the second ditch The leakage current of slot 38 (having been carried out the effect) in itself.Compared with the conventional material such as SiO2 for being used as padded coaming, aluminium compound Such as aluminium oxide (Al₂O₃) or aluminium nitride (AlN) cause gap between aluminium atom and oxygen atom and defect to be reduced, keep them close Accumulation, therefore greatly reduce leakage current.SiO in terms of breakdown reverse voltage and leakage current, in silicon carbide diode₂Passivation And Al₂O₃Comparison difference between passivation is as best shown in figures 3 a and 3b.By with Al₂O₃Instead of SiO₂As passivation, in SiO₂Situation Under leakage current 73 be improved as in Al₂O₃In the case of leakage current 72.In SiO₂In the case of the blocking voltage 71 less than 100V It is significantly increased to Al₂O₃In the case of the blocking voltage 70 greater than 600V.

From the point of view of active area, the silicon carbide diode of Fig. 1-2 b includes the first grooves 26 of multiple mixing schottky metals.Such as Shown in Fig. 4, under the reverse bias voltage condition of silicon carbide diode, by the higher barrier gold of each 26 side wall 26a of first groove Belong to generate high Schottky barrier, wider depletion region 48 is generated in silicon carbide layer 24, pinching to adjacent first trenches 26, and Protect the multiple first low barrier metal parts 36 on 24 top surface of silicon carbide layer.This is because from the big of silicon carbide substrates 20 Most reverse currents by flow through at 26 bottom of higher barrier metal and first groove at 26 side wall 26a of first groove second Low barrier metal part 34 (wherein electric current is indicated by arrow 46).Since high barrier metal exhausts pinch off protection, have no or only Very small amount of reverse current (being indicated by arrow 48) passes through the multiple first low barrier metal parts 36.

Fig. 5 a-5j illustrates how the exemplary method steps of the silicon carbide diode array of production Fig. 1-2 b.Note that In Illustrative methods described in the embodiment are not intended to be limited to the present invention, because other methods can be used and/or with different Sequence of steps makes identical silicon carbide diode.This method starts from Fig. 5 a, prepares an original silicon carbide silicon epitaxial wafer, and It is cleaned using RCA cleaning procedure.Chip has n+ type silicon carbide substrates 20 and the n-type silicon carbide layer 24 at the top of it.Then, such as Shown in Fig. 5 b, one layer of higher barrier metal 54 is deposited with a predetermined pattern, selectively on silicon carbide layer top surface.Deposition It as a result include above-mentioned third higher barrier metal part 42 and part higher barrier metal cover 22.As described above, third is higher Barrier metal part 42 is in the shape of multiple concentric annual rings.Moreover, as shown in Figure 5 b, ohmic metal 28 is deposited on silicon carbide substrates On 20 bottom surface, the cathode of silicon carbide diode is formed.

Next, as shown in Figure 5 c, silicon carbide layer 24 undergoes etch process, so that the part not covered by schottky metal Silicon carbide layer 24 is etched to form first groove 26 and second groove 38.As described above, in first groove 26 and second groove 38 are formed as concentric year colyliform.Note that being filled into first groove 26 and second groove 38 without anything at this time.It is being formed After groove, from silicon carbide top surface, especially between first groove 26 and around silicon carbide layer 24 part on, removal Some schottky metals (higher barrier metal as described above).Next, depositing one layer of atomic layer deposition first in Fig. 5 d (ALD) (such as the Al of dielectric 51₂O₃) in 24 top surface of silicon carbide layer (including first groove 26, second groove 38 and the high gesture of third Base metal part 42) on, one layer of oxide skin(coating) 50 is then deposited at the top of dielectric layer 51.

Next, silicon carbide layer 24 undergoes oxide reactive ion etch (RIE) process in Fig. 5 e, gone by the process It except the dielectric 51 and oxide 50 previously deposited on 24 top surface of silicon carbide layer, but is not first groove 26 and second groove Whole dielectrics 51 and oxide 50 inside 38.On the contrary, in the also remaining dielectric 51 of corner part and oxygen of first groove 26 The residue (not being at 26 bottom center region of first groove) of compound 50.In contrast, in the corner part of second groove 38 Point and practical entire bottom all there is the residue of dielectric 51 and oxide 50.

As shown in figure 5f, (including first groove 26,38 and of second groove on the entire top surface of 24 device of silicon carbide layer Third higher barrier metal part 42) one layer of lower barrier metal 52 of deposition.Then, low barrier metal layer 52 is undergone annealed Journey.If low barrier metal layer 52 and silicon carbide layer 24 are in direct contact with one another, they will react, but for by oxygen 24 part of carbide lamella that compound 50 covers, then without this reaction.Next, as shown in fig. 5g, being removed from device any Unreacted low barrier metal 52 keeps off metal 52 including the essentially all this low potential barrier outside active region.Next, such as Shown in Fig. 5 h, the spacer in first groove 26 is removed, is actually the residue of oxide 50, so that the only second low gesture Base metal part 34 is retained in first groove 26.

Therefore, as shown in figure 5i, higher barrier metal 54 is deposited on the active area of device, is then patterned, then Annealing, to fill first groove 26, also forms complete higher barrier metal cap 22.Finally, as shown in figure 5j, in second groove It deposition oxide 50 and is patterned in 38, so that oxide 50 becomes the dielectric material for being filled up completely second groove 38 Material, top surface are concordant with silicon carbide layer top surface.Therefore silicon carbide diode is produced.

Fig. 6 a-6d shows various other embodiments of silicon carbide diode of the present invention.For simplicity, Fig. 6 a-6d In those of same or similar feature with silicon carbide diode in Fig. 1-2 b, will not be described again here.Fig. 6 a-6d substantially compares Fig. 1-2 b includes less feature, and therefore, their performances in terms of leakage current and reverse breakdown current are not so good as the carbon of Fig. 1-2 b SiClx diode is so good.In addition, it is noted that in Fig. 6 a-6b silicon carbide diode section may be not identical in Fig. 1-2 b Ratio.In Fig. 6 a, silicon carbide diode does not include groove in active area, and active area is by the low barrier metal 152 at center and low The mixed metal of high barrier metal 154 around barrier metal 152 determines.Low barrier metal 152 does not include gap or separation also, It is a whole part.In active region, there is a circle second groove 138, is filled with dielectric material 150.The carbon of Fig. 6 b SiClx diode and the structure of Fig. 6 a are closely similar.But the difference between Fig. 6 b and Fig. 6 a is, outside the active area in Fig. 6 b Groove 238 surrounded by the buffer layer 240 of interface between dielectric material 250 and silicon carbide layer 224.Two pole of silicon carbide of Fig. 6 c Pipe with the silicon carbide diode of Fig. 6 b the difference is that, it includes multiple ditches in the silicon carbide layer 324 of active region Slot 338, each groove 338 have essentially identical size.Each groove 338 is filled with dielectric substance 350 and by buffer layer 340 surround.Multiple grooves 338 form multiple concentric annual rings in active region.Multiple high barrier metals 342 are formed in any two Between each and every one groove 338, so that metal 342 forms closed multiple concentric annual rings in a top view.Two pole of silicon carbide of Fig. 6 d Pipe with the silicon carbide diode of Fig. 6 a the difference is that, it includes multiple grooves 426, these ditches in silicon carbide layer 424 Slot position is in (similar to first groove described in Fig. 1-2 b) in active region.Each groove 426 is filled with higher barrier metal 454, in the bottom of groove 426, there is one layer of lower barrier metal 434.Multiple grooves 426 form multiple concentric in active region Annual ring.

Therefore, exemplary embodiment of the present invention is fully described.Although the description is related to specific embodiment, this Field technical staff will be clear that, by changing some details, still can practice the present invention.Therefore, the present invention should not be by It is interpreted as being limited to embodiments set forth here.

The present invention is illustrated and described in the description of attached drawing and front in detail although having passed through, should be equally considered It is illustrative rather than restrictive, it should be understood that exemplary embodiment only has shown and described, does not limit in any way The scope of the present invention processed.It is appreciated that any feature described herein can be used together with any embodiment.Illustrative implementation Example is not excluded for each other or other embodiments not enumerated herein.Therefore, the present invention also provides include said one or multiple theorys The combined embodiment of bright property embodiment.It without departing from the spirit and scope of the present invention, can be to as described herein The present invention modifies and changes, and therefore, the scope of the present invention is only subject to the contents of appended claims.

For example, the embodiment of Fig. 1-6d be have different grooves, and/or barrier metal (if from top, their shapes Concentric annual ring) silicon carbide diode.But one skilled in the art would recognize that groove and/or barrier metal can also It is other kinds of close-shaped to be formed, such as ellipse, rectangle etc..

In addition, the embodiment of Fig. 1-2 b includes a circle first groove ring and five circle second grooves, they all have substantially phase Same depth.Those skilled in the art are easily envisaged that the first groove in silicon carbide diode with different number And/or second groove, their size can be different from Fig. 1-2 b.For example, the width with the second groove close to active area It is of different size less than the second groove far from active area, it can be all second grooves with unified width.