阅读说明：本技术 半导体装置 (Semiconductor device ) 是由 平林润 藤田实 福光由章 于 2018-01-26 设计创作，主要内容包括：本发明提供沿着侧面的漏电流或侧面的破裂、缺口、裂开等难以产生的纵型结构的半导体装置。半导体装置具备：半导体层(20),其具有第一及第二电极形成面(20a、20b)和侧面(20c)；阳极电极(40),其形成于第一电极形成面(20a)；阴极电极(50),其形成于第二电极形成面(20b)；绝缘膜(30),其以覆盖第一边缘(E1)的方式从第一电极形成面(20a)遍及侧面(20c)连续地形成。根据本发明,因为半导体层(20)的侧面(20c)被绝缘膜(30)覆盖,所以沿着侧面(20c)的漏电流降低。另外,因为侧面(20c)被绝缘膜(30)保护,所以侧面(20c)的破裂、缺口、裂开等难以产生。(The present invention is provided along the leakage current of side or the rupture of side, notch, splitting etc. is difficult to the semiconductor device of the longitudinal type structure generated.Semiconductor device has: semiconductor layer (20), has first and second electrode forming surface (20a, 20b) and side (20c)；Anode electrode (40) is formed in first electrode forming face (20a)；Cathode electrode (50) is formed in second electrode forming face (20b)；Insulating film (30) is continuously formed in a manner of covering first edge (E1) from first electrode forming face (20a) throughout side (20c).According to the present invention, it because the side (20c) of semiconductor layer (20) is covered by insulating film (30), is reduced along the leakage current of side (20c).In addition, because side (20c) is protected by insulating film (30), the rupture of side (20c), notch, splitting etc. is difficult to generate.)

1. a kind of semiconductor device, which is characterized in that

Have:

Semiconductor layer, with first electrode forming face, positioned at the first electrode forming face opposite side second electrode shape It is formed at face and with the first edge as the boundary with the first electrode forming face and as with the second electrode The side of the second edge on the boundary in face；

First electrode is formed in the first electrode forming face；

Second electrode is formed in the second electrode forming face；

Insulating film spreads the continuous landform in the side from the first electrode forming face in a manner of covering the first edge At.

2. semiconductor device according to claim 1, which is characterized in that

The semiconductor layer includes to constitute the semiconductor substrate of the second electrode forming face and be set to the semiconductor substrate Epitaxial layer that is upper and constituting the first electrode forming face,

Described first at least part and the epitaxial layer Schottky contacts, the second electrode and described semiconductor substrate ohm Contact.

3. semiconductor device according to claim 2, which is characterized in that

Other a part of the first electrode is formed on the insulating film that the first electrode forming face is formed.

4. semiconductor device described in any one of claim 1 to 3, which is characterized in that

The semiconductor layer is made of gallium oxide.

5. semiconductor device according to any one of claims 1 to 4, which is characterized in that

The semiconductor layer has section from the first electrode forming face towards the widened taper of second electrode forming face Shape.

Technical field

The present invention relates to semiconductor device, more particularly to partly leading for the longitudinal type for making electric current circulate along the thickness direction of substrate Body device.

Background technique

Because power device semiconductor device needs the very big electric current that circulates, institute compared with common semiconductor device To mostly use the longitudinal type structure for making electric current circulate along the thickness direction of substrate greatly.For example, disclose has in patent document 1 The diode of longitudinal type structure.There is diode documented by patent document 1 part for being equivalent to mesa recess to be covered by protective film Structure.

Summary of the invention

Problem to be solved by the invention

But diode documented by patent document 1 exists because the side of the wafer as section is exposed, no It is only easy to produce the leakage current along side, also the problems such as being easy to produce rupture, notch on side, splitting.

Therefore, the purpose of the present invention is to provide be difficult to generate along side leakage current and side rupture, notch, split The semiconductor device for the longitudinal type structure opened etc..

Technical means to solve problem

Semiconductor device of the invention, which is characterized in that have: semiconductor layer with first electrode forming face, is located at The second electrode forming face of the opposite side of the first electrode forming face and with as with the first electrode forming face The side of the first edge on boundary and the second edge as the boundary with the second electrode forming face；First electrode, shape First electrode forming face described in Cheng Yu；Second electrode is formed in the second electrode forming face；Insulating film, to cover The mode for stating first edge is continuously formed from the first electrode forming face throughout the side.

According to the present invention, it because the side of semiconductor layer is covered by insulating film, is reduced along the leakage current of side.Separately Outside, because side is protected by insulating film, the rupture of side, notch, splitting etc. is difficult to generate.But because insulating film with The mode of covering first edge is continuously formed from first electrode forming face throughout side, so can be by non-jointed insulation Film covers first electrode forming face and side.

In the present invention, it is preferred to which the semiconductor layer includes: constitute the second electrode forming face semiconductor substrate and It is set on the semiconductor substrate and constitutes the epitaxial layer of the first electrode forming face, described first at least part and institute State epitaxial layer Schottky contacts, the second electrode and the semiconductor substrate Ohmic contact.Hereby it is possible to constitute Schottky gesture Build diode.

In this case, other a part of the first electrode, which is preferably formed in, is formed in the first electrode forming face The insulating film on.Hereby it is possible to obtain so-called field plate structure.

In the present invention, the semiconductor layer is preferably made of gallium oxide.Accordingly, because can be obtained biggish band gap and compared with Big insulation breakdown electric field, so the switch element as power device is most suitable.

In the present invention, the semiconductor layer also can have section from the first electrode forming face towards described second The widened cone-shaped of electrode forming surface.Accordingly, in side insulating film easy to form.

The effect of invention

In this way, according to the present invention, in the semiconductor device with longitudinal type structure, can reduce the leakage current along side And side rupture, notch, split.

Detailed description of the invention

Fig. 1 is the sectional view for indicating the structure of semiconductor device 10 of embodiments of the present invention.

Fig. 2 is the top view of semiconductor device 10.

Fig. 3 is the flow chart for indicating the manufacturing process of semiconductor device 10.

Fig. 4 is the sectional view of the manufacture of semiconductor device 10 on the way.

Fig. 5 is the sectional view of the manufacture of semiconductor device 10 on the way.

Fig. 6 (a) is the top view of the manufacture of semiconductor device 10 on the way, and Fig. 6 (b) is the sectional view along line B-B.

Fig. 7 is the sectional view of the manufacture of semiconductor device 10 on the way.

Fig. 8 is the sectional view of the manufacture of semiconductor device 10 on the way.

Fig. 9 is the sectional view of the manufacture of semiconductor device 10 on the way.

Figure 10 is the sectional view of the manufacture of semiconductor device 10 on the way.

Figure 11 is the sectional view of the manufacture of semiconductor device 10 on the way.

Figure 12 is the sectional view of the manufacture of semiconductor device 10 on the way.

Figure 13 is the sectional view of the manufacture of semiconductor device 10 on the way.

Figure 14 is the sectional view for the manufacturing method for illustrating the variation of semiconductor device 10.

Figure 15 is the sectional view for the manufacturing method for illustrating the variation of semiconductor device 10.

Figure 16 is to indicate that section is the sectional view of the semiconductor device 10 of cone-shaped.

Specific embodiment

Hereinafter, the preferred embodiment of the present invention is described in detail referring to attached drawing.

Fig. 1 is the sectional view for indicating the structure of semiconductor device 10 of embodiments of the present invention.In addition, Fig. 2 is partly to lead The top view of body device 10.In addition, section shown in FIG. 1 is equivalent to the section of the line A-A along Fig. 2.

The semiconductor device 10 of present embodiment is Schottky barrier diode, as shown in Figure 1, having comprising by oxidation Gallium (β-Ga₂O₃) constitute semiconductor substrate 21 and epitaxial layer 22 semiconductor layer 20.In the present invention, sometimes by semiconductor layer 20 are referred to as " gallium oxide substrate ".Silicon (Si) or tin (Sn) as n-type dopant are imported into semiconductor substrate 21 and epitaxial layer 22.About the concentration of dopant, compared to epitaxial layer 22, a side of semiconductor substrate 21 is high, 21 conduct of semiconductor substrate as a result, n⁺Layer works, and epitaxial layer 22 is used as n^-Layer works.

Semiconductor layer 20, which has, constitutes the first electrode forming face 20a in the face XY, positioned at the opposite of first electrode forming face 20a Side and four side 20c for constituting the second electrode forming face 20b in the face XY, the composition face XZ or the face YZ.First and second electrode shape It is β-Ga at face 20a, 20b₂O₃(001) face.First electrode forming face 20a is made of the upper surface of epitaxial layer 22, second electrode Forming face 20b is made of the lower surface of semiconductor substrate 21.The boundary of first electrode forming face 20a and side 20c constitute first The boundary of edge E1, second electrode forming face 20b and side 20c constitute second edge E2.

As shown in Figures 1 and 2, it is formed in first electrode forming face 20a and side 20c by SiO₂、Si₃N₄、Al₂O₃、 HfO₂Etc. compositions insulating film 30.Insulating film 30 includes first part 31 and the covering side of covering first electrode forming face 20a The second part 32 of 20c spreads the continuous landform of side 20c from first electrode forming face 20a in a manner of covering first edge E1 At.Insulating film 30 is for example by silica (SiO₂) constitute, film thickness is 300nm or so.

The first part 31 of insulating film 30 has the opening portion 30a for exposing first electrode forming face 20a.Then, The anode electrode 40 as first electrode is formed with via opening portion 30a on one electrode forming surface 20a.Anode electrode as a result, 40 with 22 Schottky contacts of epitaxial layer.Anode electrode 40 is for example made of the stacked film of platinum (Pt), titanium (Ti) and aluminium (Al), about Its film thickness, for example, platinum layer is 50nm or so, titanium layer is 5nm or so, and aluminium layer is 1 μm or so.

The major part of anode electrode 40 and 22 Schottky contacts of epitaxial layer, but the of other a part covering insulating film 30 A part 31.So-called field plate structure is obtained as a result,.In general, electric field concentrates on anode electrode in Schottky barrier diode End, therefore, when the part is more than insulation breakdown electric field strength, element is destroyed.But as in the present embodiment, such as The end of anode electrode 40 is formed on insulating film 30 by fruit, then the current convergence on end is alleviated, and therefore, can be improved anti- Direction pressure resistance.

On the other hand, the second electrode forming face 20b of semiconductor layer 20 is provided with the cathode electrode as second electrode 50.Cathode electrode 50 is made of titanium (Ti), nickel (Ni) and the stacked film of golden (Au) etc., and with 21 Ohmic contact of semiconductor substrate. For example, titanium layer with a thickness of 50nm or so, nickel layer with a thickness of 0.2 μm or so, layer gold with a thickness of 0.2 μm or so.

According to above structure, the semiconductor device 10 of present embodiment constitutes Schottky barrier diode.Schottky gesture It builds diode and is used for switch element, by applying forward bias, anode electrode 40 between anode electrode 40 and cathode electrode 50 It is reduced with the Schottky barrier on the interface of epitaxial layer 22, electric current flows to cathode electrode 50 from anode electrode 40.On the other hand, such as Fruit applies reverse biased between anode electrode 40 and cathode electrode 50, then Xiao on the interface of anode electrode 40 and epitaxial layer 22 Special base barrier is got higher, and electric current hardly circulates.

Then, in the semiconductor device 10 of present embodiment, because the side 20c of semiconductor layer 20 is covered by insulating film, So the leakage current along side 20c reduces, and the rupture of side 20c, notch, splitting etc. is difficult to generate.But because absolutely Velum 30 is continuously formed in a manner of covering first edge E1 from first electrode forming face 20a throughout side 20c, so with dividing The insulating film for not individually forming covering first electrode forming face 20a is compared with the case where insulating film of covering side 20c, into one Step improves said effect.In addition, can also prevent rupture and notch of the gallium oxide substrate in first edge E1 etc..

Then, the manufacturing method of the semiconductor device of present embodiment 10 is illustrated.

Fig. 3 is the flow chart for indicating the manufacturing process of semiconductor device 10 of present embodiment.

Firstly, as shown in figure 4, preparing gallium oxide wafer made of being sliced the crystal block for using the incubations such as melt growth method W, and it is formed on its surface epitaxial layer 22.It can be by using reactive sputtering, PLD method, MBE on the surface of gallium oxide wafer W Method, mocvd method, HVPE method etc. make gallium oxide epitaxial growth and form epitaxial layer 22.The carrier concentration and film thickness of epitaxial layer 22 It is adjusted in a manner of ensuring corresponding to the pressure resistance of design.As an example, the reverse withstand voltage of 600V or so in order to obtain, as long as by thick Degree is set as 7~8 μm, and carrier concentration is set as 1 × 10¹⁶cm^-3Left and right.The control of carrier concentration is by by Si, Sn etc. The dopant that carrier as N-shaped works imports desired amount in film forming and carries out.It is completed as a result, in gallium oxide crystalline substance The surface of piece W is formed with the gallium oxide substrate (step S1) of epitaxial layer 22.

Then, as shown in figure 5, by the first electrode shape for using etching to use mask M1 covering as the surface of epitaxial layer 22 Dry ecthing is carried out at being formed in the state of the element-forming region of element in the 20a of face, forms multiple slits in gallium oxide substrate 60 (step S2).Slit 60 penetrates through epitaxial layer 22, is set as reaching the depth of gallium oxide wafer W.Specifically, by slit 60 Depth is set as slightly deeper than the thickness of final semiconductor layer 20.For example, if final semiconductor layer 20 with a thickness of 50 μ M, as long as the depth of slit 60 is then set as 55 μm or so.

The formation of slit 60 can be by using BCl₃Etc. the RIE methods of chlorine gases carry out.Especially for shortening Etching period, it is preferable to use can high-rate etching ICP-RIE method.As etching mask M1, such as in order to Ga₂O₃With choosing Selecting property is not, it is preferable to use by metal films such as the nickel (Ni) of chlorine gas etching.As long as in this case, as etching with mask M1's Metal film forms 100nm or so using EB vapour deposition method, sputtering method etc., forms etching mask in the entire surface of epitaxial layer 22 After M1, as long as being patterned by photoetching process.Then, by the etching that will be patterned into use mask M1 as mask into Row dry ecthing, to form multiple slits 60 in gallium oxide substrate.

Such as shown in Fig. 6 (a) of top view, slit 60 formed in x-direction and y-direction it is multiple, by slit when vertical view 60 rectangular areas surrounded are the part for eventually becoming element.Fig. 6 (b) is the substantially section along line B-B shown in Fig. 6 (a) Figure.As an example, in the case where component size is set as 1mm × 1mm, as long as being 20 μm of slit 60 with 1.02mm by width Pitch is formed in x-direction and y-direction.After forming slit 60, using the removal etching of common acids etching solution with covering Mould M1 carries out base-plate cleaning.

The slit 60 formed in this way is different from having used the machining of cutter etc. to be formed by slit, in inner wall more than 61 Damage is not generated.In addition, the flatness of inner wall 61 is also very high, specifically, concave-convex is 1 μm hereinafter, its superficiality is also big It causes uniform.

Then, as shown in fig. 7, being formed on the surface of epitaxial layer 22 and the inner wall 61 of slit 60 by SiO₂、Si₃N₄、Al₂O₃、 HfO₂Etc. compositions insulating film 30 (step S3).It is preferable to use the coverage rates such as ALD method or CVD method are excellent for the forming method of insulating film 30 Different film build method, the not only surface of epitaxial layer 22 as a result, and also the almost entire surface of the inner wall 61 of slit 60 is by insulating film 30 Covering.In addition, the part first edge E1 of the opening portion as slit 60 is also covered by insulating film 30.Insulating film 30 can also group Multiple film build methods are closed to be laminated.

Then, as shown in figure 8, after insulating film 30 forms opening portion 30a, as shown in figure 9, forming the (step of anode electrode 40 Rapid S4).As long as the formation of opening portion 30a is after will be Resist patterning by common photoetching process, using resist as covering Mould carries out dry ecthing or wet etching to insulating film 30.But it because is formed at the time point in gallium oxide substrate multiple Slit 60, so, it is preferable to use the solid resist of film-type is as resist compared with the liquid resist of application type.

Anode electrode 40 can be formed by vapour deposition method, and be able to use stripping process and patterned.That is, firstly, In After forming corrosion-resisting pattern of the planar dimension than big 5 μm of opening portion 30a or so of insulating film 30, platinum (Pt) is formed by vapour deposition method 50nm, titanium (Ti) is formed into 5nm, aluminium (Al) is formed 1 μm or so.It then, can be by resist pattern if removal corrosion-resisting pattern Metal layer in case is removed together with corrosion-resisting pattern.Here, in order to inhibit metal film to be attached in slit 60, it is preferable to use thin The solid resist of membranous type.Alternatively, the anode electrode 40 that can not also will be formed in entire surface patterns, and via clathrate Metal mask etc. is deposited, and thus anode electrode 40 selectively forms a film.But in the present embodiment, because of slit 60 inner wall 61 is covered by insulating film 30, so even if a small amount of metal material invades in slit 60, it will not be with oxidation Gallium substrate connects.

Then, as shown in Figure 10, attaching on the surface of gallium oxide substrate has flexible bearing part 70 (step S5). As there is flexible bearing part 70, it is preferable to use the high component of flexibility as thick resin film.Will be this soft After soft high bearing part 70 attaches to the surface of gallium oxide substrate, if applying pressure to a certain degree, bearing part 70 deformations, part of it become the guard block 80 for being embedded to slit 60.By the guard block 80, spatially from slit 60 Cover anode electrode 40.

Then, as shown in figure 11, in the state of supporting gallium oxide substrate by bearing part 70, to back side, i.e. oxygen The lower surface for changing gallium wafer W carries out grinding and grinding (step S6).Grinding and grinding can be by grinding with common silicon substrate Same method is cut and grinds to carry out.The grinding of gallium oxide wafer W and grinding are carried out to slit 60 is reached, as a result, by semiconductor It is multiple that the gallium oxide substrate that substrate 21 and epitaxial layer 22 are constituted, which is singulated,.It is clear by carrying out after carrying out grinding and grinding It washes and cleans abradant surface.Alternatively, it is also possible to without grinding, and singualtion is only carried out by grinding.

Then, as shown in figure 12, (the step of cathode electrode 50 is formed in the lower surface for the semiconductor substrate 21 being made of gallium oxide Rapid S7).It is preferable to use the low film engineering methods of the coverage rates such as vapour deposition method or sputtering method for cathode electrode 50 to be formed.Accordingly, it is partly leading The lower surface of structure base board 21 correctly forms a film cathode electrode 50, on the other hand, since 61 electrode material of inner wall in slit 60 is several Not around entering, so in inner wall 61 almost without forming electrode.A part intrusion slit of the electrode material of cathode electrode 50 In 60, but as shown in figure 12, it is preferable that because the upper part of slit 60 utilizes the protection portion being made of a part of bearing part 70 Part 80 is embedded to, so the electrode material of cathode electrode 5 does not reach anode electrode 40.Electrode material invades slit in order to prevent In 60, it is deposited etc. in the state that the metal mask etc. by clathrate covers slit 60, thus by cathode electrode 50 half The lower surface of conductor substrate 21 selectively forms a film.

Then, as shown in figure 13, if removing the bearing part 70, (step that completes of multiple semiconductor devices 10 S8).The semiconductor device 10 being singulated is equipped on packaging body as needed.Packaging body has the bottom being made of copper (Cu) etc. The cathode electrode 50 of plate, semiconductor device 10 is connect via solder with bottom plate.The anode electrode 40 of semiconductor device 10 is via connecing The connection of the lead frame of zygonema and packaging body.

In this way, the manufacturing method of semiconductor device 10 according to the present embodiment, by dry ecthing in gallium oxide substrate After upper surface side forms multiple slits 60, by grinding and grinding by the lower face side singualtion of gallium oxide substrate, so partly leading The side 20c of body layer 20 not will receive mechanical injuries.Therefore, from use cutter etc. carry out singualtion the case where different, In Side 20c does not generate rupture, notch, splits.Especially β-Ga₂O₃(100) face and (001) face have it is fissility, because This, is β-Ga in electrode forming surface 20a, 20b₂O₃(001) face in the case where, when carrying out singualtion using cutter etc., have When in side 20c generate multiple split in the horizontal direction.When generating this split, not only equipment energy characteristic may change, but also Since the gallium oxide powder for generation of splitting may also disperse.But the manufacturing method of semiconductor device 10 according to the present embodiment, Because side 20c is the face formed by dry ecthing, this split hardly is generated.Even if assuming to generate a small amount of split It opens, because side 20c is covered by insulating film 30, gallium oxide powder will not disperse.In addition, due to the heat transfer of gallium oxide Rate is low, and accordingly, there exist the outside that the fever caused by forward current will not effectively reject heat to element, element is easy deterioration in this way The problem of.But in the present embodiment, because being thinned semiconductor layer 20 by the back side for grinding gallium oxide wafer W, So also can be improved thermal diffusivity.

Moreover, formed for obtaining the insulating film 30 of field plate structure when because slit 60 inner wall 61 also simultaneously shape At insulating film 30, so not increasing process number, and can be in the both sides of first electrode forming face 20a and the inner wall 61 of slit 60 Form insulating film 30.In this way, because being formed in the insulating film 30 (first part 31) of first electrode forming face 20a and being formed in side The insulating film 30 (second part 32) of face 20c is formed simultaneously, so therebetween without seam etc..It therefore, can be effectively Inhibit the leakage current along side 20c.

In addition, in above-mentioned manufacturing method, it, will be by bearing part 70 by using having flexible bearing part 70 The guard block 80 that a part is constituted is embedded to the top of slit 60, but low using rigid bearing part 70 or pliability In the case where bearing part 70, as shown in figure 14, can also after forming slit 60, before by gallium oxide substrate singualtion, The guard block 80 different from bearing part 70 is embedded to slit 60.In addition, the embedment of guard block 80 can also be by oxygen Change gallium substrate singualtion later and is carried out before forming cathode electrode 50.In short, if will protection when forming cathode electrode 50 Component 80 is embedded to slit 60, even if then the electrode material of cathode electrode 50 invades slit 60, which will not be reached Anode electrode 40.

It, can also be by adjusting the condition of dry ecthing, and such as Figure 15 in addition, in the process (step S2) for forming slit 60 The slit 60 of cone cell before shown formation.So-called inner cone refers to the shape that slit width narrows gradually along depth direction.Accordingly, In It is formed in the process (step S3) of insulating film 30, it is easy to form excellent as the inner wall 61 of slit 60 that insulating film 30 can be obtained Point.In the case where forming slit 60 of this preceding cone cell, the shape of finally obtained semiconductor device 10 becomes such as Figure 16 institute Show the section XY of semiconductor layer 20 from first electrode forming face 20a towards the widened cone-shaped of second electrode forming face 20b.It is this Shape facilitates the carrying stability on packaging body.

More than, the preferred embodiment of the present invention is illustrated, but the present invention is not limited to above embodiment, In Not departing from can make various changes in the range of spirit of the invention, and much less these changes are also contained in the scope of the present invention It is interior.

For example, in the above-described embodiment, being carried out in case where applying the present invention to Schottky barrier diode Explanation, but the present invention is not limited thereto, if it is the semiconductor device for the longitudinal type that electric current is flowed along the thickness direction of substrate, It can also apply to other kinds of semiconductor device.

In addition, in the above-described embodiment, use gallium oxide as the material of semiconductor layer, but the present invention is not limited to This.

The explanation of symbol

10 semiconductor devices

20 semiconductor layers

20a first electrode forming face

20b second electrode forming face

The side 20c

21 semiconductor substrates

22 epitaxial layers

30 insulating films

The opening portion 30a

31 first parts

32 second parts

40 anode electrodes

50 cathode electrodes

60 slits

61 inner walls

70 bearing parts

80 guard blocks

E1 first edge

E2 second edge

Mask is used in M1 etching

W gallium oxide wafer.