JPWO2013099050A1 - Silicon carbide semiconductor device manufacturing method, silicon carbide semiconductor device, and silicon carbide semiconductor module - Google Patents

Abstract

A silicon carbide semiconductor element in which a conductive layer is accurately and simply formed on the end surface is obtained. A plurality of semiconductor devices 18 formed on silicon carbide semiconductor device substrate 1a are cut into respective silicon carbide semiconductor elements by an electric discharge machining method, and silicon carbide substrate 11 of silicon carbide semiconductor device substrate 1a is formed on an end side surface of the silicon carbide semiconductor element. Forming a conductive layer 17 having a volume resistivity lower than the volume resistivity.

Description

  The present invention relates to a method for manufacturing a silicon carbide semiconductor element, a silicon carbide semiconductor element, and a silicon carbide semiconductor module, and more specifically, a method for manufacturing a silicon carbide semiconductor element having high reliability against discharge breakdown, and a silicon carbide semiconductor element and silicon carbide. The present invention relates to a semiconductor module.

  In a silicon carbide semiconductor element, since a high voltage is applied, it is known that charges are easily accumulated on the end side surface of the silicon carbide semiconductor element, and the accumulated charges cause creeping discharge and the element is destroyed.

  In order to prevent this creeping discharge, a metal film is formed on the surface of the silicon carbide semiconductor element, and a high voltage is applied to the silicon carbide semiconductor element to localize charges accumulated on the side surfaces of the silicon carbide semiconductor element. A prevention method (for example, Patent Document 1) has been proposed.

JP 2009-224641 A

  In order to prevent creeping discharge, when a conductive layer such as a metal film is formed on the surface of the silicon carbide semiconductor element, it is necessary to form the conductive layer also on the four side surfaces of the silicon carbide semiconductor element. However, the thickness of the cut silicon carbide semiconductor element is thin and is usually 350 μm or less. There is a problem that it is very difficult to accurately and simply form a conductive layer made of a conductive paste, a metal vapor deposition film, solder, or the like on the side surface of the silicon carbide semiconductor element.

  The present invention has been made to solve such a problem, and a conductive layer is accurately and simply formed on the end side surface of a silicon carbide semiconductor element to prevent creeping discharge of the silicon carbide semiconductor element, thereby improving reliability. An object of the present invention is to obtain a high silicon carbide semiconductor element manufacturing method, a silicon carbide semiconductor element, and a silicon carbide semiconductor module.

  A method for manufacturing a silicon carbide semiconductor element of the present invention includes cutting a plurality of semiconductor devices formed on a silicon carbide semiconductor device substrate into respective silicon carbide semiconductor elements by an electric discharge machining method, and forming silicon carbide on an end side surface of the silicon carbide semiconductor element. The method includes a step of forming a conductive layer having a volume resistivity lower than that of the silicon carbide substrate of the semiconductor device substrate.

  Moreover, the silicon carbide semiconductor element of this invention is equipped with the silicon deficiency layer which has a volume resistivity lower than the volume resistivity of a silicon carbide base | substrate at the end side surface of a silicon carbide semiconductor element.

  By using the manufacturing method of the present invention, a conductive layer having a volume resistivity lower than the volume resistivity of the silicon carbide substrate is accurately and simply formed on the end side surface of the silicon carbide semiconductor element produced by cutting the silicon carbide semiconductor device substrate. The creeping discharge seen when a high voltage is applied to the silicon carbide semiconductor element can be prevented, and a highly reliable silicon carbide semiconductor element manufacturing method can be obtained.

  In addition, the silicon carbide semiconductor element of the present invention has a silicon-deficient layer having a volume resistivity lower than that of the silicon carbide substrate on the side surface of the silicon carbide semiconductor element, so that the occurrence of creeping discharge is suppressed and the carbonization is highly reliable. A silicon semiconductor element can be obtained. Further, as a secondary effect, the surface roughness of the conductive layer formed on the end side surface of the silicon carbide semiconductor element by electric discharge machining is 0.1 μm or more and 10 μm or less. A silicon carbide semiconductor element having improved adhesion to the resin covering it can be obtained.

1 is a schematic diagram of a wire cut electric discharge machine used in Embodiment 1. FIG. 2 is a schematic cross-sectional view of a Schottky barrier diode in Embodiment 1. FIG. It is the schematic of the multi wire cut electric discharge machine used in Embodiment 2. FIG. FIG. 12 is a schematic top view showing a surface cooling mechanism during electric discharge machining of a silicon carbide semiconductor device substrate in a third embodiment. FIG. 11 is a schematic cross sectional view showing a surface cooling mechanism during electric discharge machining of a silicon carbide semiconductor device substrate in the third embodiment. (A) is the pulse voltage characteristic applied between the silicon carbide semiconductor device substrate and wire wire in Embodiment 4, (b) is a schematic diagram of the surface roughness when processed on the conditions. 6 is an AFM (Atomic force microscope) image of the surface of a conductive layer formed on an end side surface of a silicon carbide semiconductor element when the silicon carbide semiconductor element is cut from a silicon carbide semiconductor device substrate manufactured under the conditions shown in Embodiment 4. .

  In the description of the embodiments and the respective drawings, the portions denoted by the same reference numerals indicate the same or corresponding portions. In the embodiment, the silicon carbide semiconductor device substrate refers to a silicon carbide wafer substrate in which semiconductor devices such as diodes and transistors are formed, and the silicon carbide semiconductor element is cut out from the silicon carbide semiconductor device substrate. 1 shows a semiconductor device having a function as an electronic component by itself. In addition, the silicon carbide semiconductor module indicates a state in which one or a plurality of silicon carbide semiconductor elements are combined with other electronic components as necessary to operate and function. In addition, as a silicon carbide semiconductor element, various diodes, such as a Schottky barrier diode, may be sufficient as various transistors, such as MOSFET (field effect transistor), and also the combination of those semiconductor elements. Not too long.

Embodiment 1 FIG.
<Cutting of silicon carbide semiconductor device substrate>
The cutting process of silicon carbide semiconductor device substrate 1a in the present embodiment will be described using FIG. FIG. 1 is a schematic view of the wire cut electric discharge machine used in the first embodiment.

  A plurality of semiconductor devices are formed on silicon carbide semiconductor device substrate 1a, and thereafter, silicon carbide semiconductor device substrate 1a is cut using an electric discharge machining method to cut out individual silicon carbide semiconductor elements. In the present embodiment, a silicon carbide Schottky barrier diode was formed on silicon carbide semiconductor device substrate 1a and cut out to obtain a silicon carbide Schottky barrier diode element. The structure of the silicon carbide Schottky barrier diode will be described later.

  As shown in FIG. 1, in the present embodiment, a single wire type wire cut electric discharge machine is used. The wire-cut electric discharge machine has a wire wire 3a hung on a wire guide 2a, a stage 4a that can be moved in an XY plane, a stage controller 5a that moves the stage and changes the cutting position, It comprises a machining power source 6a for applying a pulse voltage to the wire, a wire controller 7a for controlling the wire wire feed, and an electric discharge machining controller 8a for controlling the entire electric discharge machining process.

  Silicon carbide semiconductor device substrate 1a on which a plurality of silicon carbide Schottky barrier diodes are formed is fixed to stage 4a using a conductive dicing tape. A pulse voltage is applied from the machining power supply 6a to the wire 3a and the silicon carbide semiconductor device substrate 1a to start cutting. Cut from the end of silicon carbide semiconductor device substrate 1a, stage 4a is moved by stage control portion 5a, silicon carbide semiconductor device substrate 1a is cut, and a silicon carbide semiconductor element is cut out.

  In the present embodiment, the wire wire 3a of the electric discharge machine is a steel wire having a diameter of 50 μm and coated with brass having a thickness of 1 μm. Moreover, the pulse voltage applied to the wire line 3a was applied by connecting the wire line side as (−) and the silicon carbide semiconductor device substrate 1a side as (+). The pulse width was 1 μsec (25% duty), a pulse voltage of 80 V was applied, the feed rate of the wire 3a was 0.5 mm / min, and cutting was performed in pure water.

<Configuration of silicon carbide Schottky barrier diode>
The configuration of the silicon carbide Schottky barrier diode in the present embodiment will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view of the Schottky barrier diode in the first embodiment.

  N-type silicon carbide epitaxial layer 10 is formed on n-type and low-resistance silicon carbide substrate 9. In the present embodiment, silicon carbide substrate 9 and silicon carbide epitaxial layer 10 are collectively referred to as silicon carbide substrate 11. The silicon carbide substrate 9 used here is a silicon carbide substrate having a crystal structure of 4H, and has a crystal structure in which the hexagonal (0001) plane is inclined by 8 ° or 4 ° from the surface of the silicon carbide substrate.

  On the surface of silicon carbide epitaxial layer 10, an ion implantation region 12 containing, for example, aluminum (Al) as a p-type impurity is formed in a ring shape. A Schottky electrode 13 is formed on the surface of the silicon carbide epitaxial layer 10 surrounded by the ion implantation region 12 so that the periphery covers a part of the surface of the ion implantation layer 12. An anode electrode 14 is formed on the substrate.

  Further, an insulating layer 15 made of polyimide is formed so as to cover the surface of silicon carbide epitaxial layer 10.

  Cathode electrode 16 is formed on the back surface of silicon carbide substrate 9, that is, the surface opposite to the surface on which n-type silicon carbide epitaxial layer 10 is formed. Here, Ni (nickel) is used for the cathode electrode 16, and after forming the electrode, it is heated to about 1000 ° C. to be silicided.

  Furthermore, in the silicon carbide semiconductor element of the silicon carbide Schottky barrier diode of the present embodiment, conductive layer 17 is formed on the four end side surfaces of silicon carbide substrate 11, that is, the four surfaces cut by the electric discharge machine.

<About conductive layer>
Although the volume resistivity of the conductive layer 17 formed on the side surface of the silicon carbide semiconductor element of the silicon carbide Schottky barrier diode cut by the electric discharge machine varies depending on the cutting conditions of the electric discharge machine, it is mainly 2-7 Ωcm. In other words, the resistance was very low as compared with the silicon carbide substrate 9 and the silicon carbide epitaxial layer 10 constituting the silicon carbide substrate 11. The film thickness of the conductive layer 17 was 15 μm.

  Conductive layer 17 formed on the side surface of the silicon carbide semiconductor element has a lower silicon element ratio than silicon carbide substrate 9 and silicon carbide epitaxial layer 10 and is a carbon-rich layer, in other words, a silicon-deficient layer. The crystal structure of the silicon carbide other than the end face is hexagonal 4H, but it has been confirmed that the low resistance silicon-deficient layer has lower crystallinity than the silicon carbide substrate 9 and the silicon carbide epitaxial layer 10. It was.

  As a result of the above examination on the conductive layer 17, it was found that the conductive layer 17 formed on the end side surface of the silicon carbide semiconductor element cut by the electric discharge machining is a low-resistance silicon-deficient layer.

  In the cutting process by this electric discharge machining method, silicon carbide in the cut portion is heated to a very high temperature and melted. When heated further, the boiling point of silicon is lower when carbon and silicon are compared, so that silicon is preferentially vaporized, and carbon is considered to remain in a molten state without being vaporized.

  In this state, when the silicon carbide semiconductor element of the silicon carbide Schottky barrier diode is cut and cooled, the end side portion of the silicon carbide semiconductor element is deficient in silicon as compared with normal silicon carbide. It is thought that the low-resistance silicon-deficient layer was formed.

<Effect of low resistance silicon-deficient layer>
As described above, from the silicon carbide semiconductor device substrate 1a having the silicon deficient layer (conductive layer 17) having a volume resistivity lower than the volume resistivity of the silicon carbide substrate at the end side portion of the silicon carbide semiconductor element, the electric discharge machining method is performed. The silicon carbide semiconductor element of the silicon carbide Schottky barrier diode cut out by using no shows creeping discharge even when a high voltage is applied, and exhibits high reliability without causing discharge breakdown.

  Furthermore, even when a silicon carbide semiconductor element cut out from the silicon carbide semiconductor device substrate 1a by using an electric discharge machining method is packaged and evaluated by applying a high voltage, high reliability that does not cause discharge breakdown is obtained. .

  Since the silicon deficient layer having a volume resistivity lower than the volume resistivity of the silicon carbide substrate, which is the conductive layer 17, is formed during the step of cutting by the electric discharge machine, the cut surface, that is, the end of the silicon carbide semiconductor element is formed. Since it can be accurately formed on the side surface and a new process is not required, creeping discharge when a high voltage is applied to the silicon carbide semiconductor element can be easily prevented, and high reliability can be obtained.

  In the present embodiment, the wire wire 3a has a diameter of 50 μm, but is not particularly limited, and any wire wire 3a having a diameter of 25 μm to 500 μm can be used. However, with a thin wire, a sufficient current cannot flow, and the processing speed may be very slow. In the case of being thick, the processing width (the width that is melted and removed) when cutting is generally slightly larger than the diameter of the wire, and is not suitable for cutting out fine silicon carbide semiconductor elements. From such a viewpoint, the diameter of the wire 3a is preferably 50 μm to 100 μm.

  In the present embodiment, the pulse voltage is 80 V, the pulse width is 1 μsec (25% duty), and the wire feed speed is 0.5 mm / min. However, the present invention is not particularly limited, and the silicon carbide semiconductor device substrate 1a to be cut It can be determined based on characteristics, thickness, and the like. Specifically, the pulse voltage can be adjusted in the range of 50 V to 300 V, pulse width of 0.1 to 10 μs, 10 to 80% duty, and wire feed speed of 0.1 mm to 10 mm / min according to the cutting condition. preferable.

  In this embodiment, Ti is used for the Schottky electrode 13, but it is not particularly limited, and Mo or the like can be used. Further, although Al is used for the anode electrode 14, it is not particularly limited, and a metal film such as Cu or Al / Ni / Au can be used.

Furthermore, the insulating film 15 covering the surface of the silicon carbide epitaxial layer 10 is polyimide was used, not particularly limited, has an insulating property, as long as it can be formed into a silicon carbide substrate surface, SiO _2, An inorganic film such as SOG (Spin on Glass) can also be used.

  The volume resistivity of the silicon-deficient layer (conductive layer 17) having a volume resistivity lower than the volume resistivity of the silicon carbide substrate at the end side portion of the silicon carbide semiconductor element is not particularly limited, but is 7 Ωcm or less. Is preferred. If it is 7 Ωcm or less, the effect of not localizing the accumulated charge is remarkable, and creeping discharge of the silicon carbide semiconductor element can be reliably prevented.

  The film thickness of the silicon-deficient layer (conductive layer 17) having a volume resistivity lower than the volume resistivity of the silicon carbide substrate at the end side portion of the silicon carbide semiconductor element is not particularly limited. From the viewpoint that the low-resistance silicon-deficient layer (conductive layer 17) is stable due to scratches, impacts, and the like in the manufacturing process, it is preferably 10 μm or more and 20 μm or less.

  In the present embodiment, an example is shown in which a silicon carbide Schottky barrier diode, which is a silicon carbide semiconductor element created on silicon carbide semiconductor device substrate 1a, is cut, but an electric field that is another silicon carbide semiconductor element. Even if it is an effect semiconductor (MOSFET etc.) and an insulated gate bipolar semiconductor (IGBT), the same effect, specifically, a low-resistance silicon-deficient layer can be accurately and easily formed on the end side surface of the silicon carbide semiconductor element. The creeping discharge at the time of applying a high voltage can be prevented, and the silicon carbide semiconductor module using the silicon carbide semiconductor element can obtain high reliability.

Embodiment 2
<Cutting of silicon carbide semiconductor device substrate>
The cutting process of silicon carbide semiconductor device substrate 1b in the present embodiment will be described using FIG. FIG. 3 is a schematic view of the multi-wire cut electric discharge machine used in the second embodiment.

  In the first embodiment, an electric discharge machine using one wire 3a is used. However, in this embodiment, a silicon carbide semiconductor element can be more efficiently cut out from silicon carbide semiconductor device substrate 1b. A multi-wire electric discharge machine is used so that it can do.

  The electric discharge machining control unit 8b sends signals to the stage control unit 5b, the machining power source 6b, and the wire control unit 7b. The wire control unit 7b adjusts and controls the feed voltage of the wire 3b according to the processing conditions and the like input to a control computer (not shown).

  First, silicon carbide semiconductor device substrate 1b in which a silicon carbide Schottky barrier diode similar to that of the first embodiment is formed on stage 4b is bonded and fixed on a conductive dicing protective tape. The height of the stage 4b is adjusted so that the silicon carbide semiconductor device substrate 1b and the wire wire 3b maintain a predetermined gap.

  While moving wire wire 3b hung on wire guide 2b at a constant feed rate, a pulse voltage is applied to wire wire 3b to cut silicon carbide semiconductor device substrate 1b. When the surface of silicon carbide semiconductor device substrate 1b is melted and cut, the height of stage 4b is sequentially adjusted so as to maintain the gap between silicon carbide semiconductor device substrate 1b and wire wire 3b. This process is continuously repeated to cut silicon carbide semiconductor device substrate 1b, and a silicon carbide Schottky barrier diode is cut out for each individual silicon carbide semiconductor element.

<Configuration of silicon carbide Schottky barrier diode, etc.>
The silicon carbide semiconductor element of the cut silicon carbide Schottky barrier diode has the configuration shown in FIG. 2 as in the first embodiment, and a low-resistance silicon-deficient layer, which is conductive layer 17, is formed on the cut surface. . This low-resistance silicon-deficient layer had a volume low efficiency of 5 Ωcm and a film thickness of about 15 μm.

<Effect of low resistance silicon-deficient layer>
As described above, silicon carbide, which is a silicon carbide semiconductor element cut out from a silicon carbide semiconductor device substrate 1b using a multi-wire cut electric discharge machine, having a low-resistance silicon-deficient layer as the conductive layer 17 on the end side portion thereof. The Schottky barrier diode did not cause creeping discharge even when a high voltage was applied, and showed high reliability.

  Further, a silicon carbide semiconductor module using a silicon carbide semiconductor element cut out from the silicon carbide semiconductor device substrate 1b by using an electric discharge machining method has high reliability that does not cause discharge breakdown even when evaluated by applying a high voltage. was gotten.

  Since this low-resistance silicon-deficient layer is formed during the process of cutting with an electric discharge machine, it can be accurately formed on the cut surface, that is, the end side surface of the silicon carbide semiconductor element, and no new process is required. Therefore, a low-resistance silicon-deficient layer as the conductive layer 17 can be easily formed on the end side surface of the silicon carbide semiconductor element, and a highly reliable silicon carbide semiconductor element of a silicon carbide Schottky barrier diode can be obtained. Moreover, the silicon carbide semiconductor module using this silicon carbide semiconductor element can obtain high reliability.

  In the present embodiment, the wire wire 3b was cut under the conditions of a diameter of 75 μm, a pulse voltage of 150 V, and a pulse width of 0.2 μsec (50% duty), but is not particularly limited, and silicon carbide to be cut It can be determined based on the characteristics, thickness, etc. of the semiconductor device substrate 1b. Specifically, in the same manner as in the first embodiment, the cutting voltage is within a range of a pulse voltage of 50 V to 300 V, a pulse width of 0.1 to 10 μsec, a 10 to 80% duty, and a wire feed speed of 0.1 mm to 10 mm / min. It is preferable to adjust according to.

Embodiment 3
Using the multi-wire cut electric discharge machine of the second embodiment, silicon carbide semiconductor device substrate 1c on which a silicon carbide Schottky barrier diode that is a silicon carbide semiconductor element similar to that of the first embodiment was formed was cut. In the present embodiment, as shown in FIG. 4, cooling plate 19 is attached on silicon carbide semiconductor device substrate 1c to be cut.

  FIG. 4 is a schematic top view showing a surface cooling mechanism during electric discharge machining of silicon carbide semiconductor device substrate 1c in the third embodiment, and FIG. 5 shows a surface cooling mechanism during electric discharge machining of silicon carbide semiconductor device substrate 1c in the third embodiment. It is a cross-sectional schematic diagram which shows. In the multi-wire cut electric discharge machine, the silicon carbide semiconductor device substrate 1c is cut simultaneously using a plurality of wire wires 3c, but in order to simplify the configuration in FIG. 4, only one wire wire 3c is focused, The positional relationship among the wire 3c, the silicon carbide semiconductor device substrate 1c, the semiconductor device 18 and the cooling plate 19 is illustrated.

  Cooling plate 19 is made of copper, and is attached to the surface of silicon carbide semiconductor device substrate 1c with a certain gap so as to sandwich wire wire 3c. When cutting by the electric discharge machining method, a cutting portion adjacent to the wire 3c is heated to a very high temperature and is cut by being melted. If not immediately cooled after cutting, a resin that forms an insulating layer (not shown in FIG. 5, but corresponds to the insulating layer 15 in FIG. 2) of the semiconductor device 18 formed on the silicon carbide semiconductor device substrate 1c. An electrode material such as a membrane or an anode electrode may be deteriorated by the influence of the heat.

  Therefore, in the present embodiment, a cooling plate 19 is attached so that silicon carbide semiconductor device substrate 1c can be immediately cooled after being cut by electric discharge machining, and the silicon carbide semiconductor is cut under the same cutting conditions as in the second embodiment. The device substrate 1c was cut.

  By cutting silicon carbide semiconductor device substrate 1c provided with cooling plate 19 shown in the present embodiment, silicon carbide semiconductor device substrate 1c is cooled after cutting, so that there is no deterioration of the resin film or electrode material forming the insulating film. Thus, a silicon carbide semiconductor element of a silicon carbide Schottky barrier diode was obtained.

  In addition, a low-resistance silicon-deficient layer, which is the conductive layer 17, is formed on the side surface of the silicon carbide semiconductor element, which is a cut surface of the silicon carbide semiconductor element of the silicon carbide Schottky barrier diode. Even when a high voltage is applied, creeping discharge does not occur and high reliability is exhibited.

  Further, the silicon carbide semiconductor module using the silicon carbide semiconductor element cut out from the silicon carbide semiconductor device substrate 1c by using the electric discharge machining method also has high reliability that does not cause discharge breakdown even when evaluated by applying a high voltage. was gotten.

  Since this low-resistance silicon-deficient layer is formed during the process of cutting with an electric discharge machine, it can be accurately formed on the cut surface, that is, the end side surface of the silicon carbide semiconductor element, and no new process is required. Therefore, the reliability of the silicon carbide semiconductor element can be easily increased.

  Needless to say, the silicon carbide semiconductor element made of silicon carbide obtained in each of the above-described embodiments can be used as a silicon carbide semiconductor module in combination with other semiconductor elements and other electronic components.

Embodiment 4
Using the multi-wire cut electric discharge machine of the second embodiment, silicon carbide semiconductor device substrate 1d on which a silicon carbide Schottky barrier diode, which is a silicon carbide semiconductor element similar to that of the first embodiment, was formed was cut. In Embodiments 1 to 3, after cutting the silicon carbide semiconductor device substrate, evaluation has been made mainly on the volume resistivity of the conductive layer 17 formed on the end side surface of the silicon carbide semiconductor element, and reliability against discharge breakdown. In the present embodiment, paying attention to the surface roughness (Ra) of the conductive layer 17, the adhesion of the resin film formed on the surface of the silicon carbide semiconductor element was evaluated.

  FIG. 6A shows a pulse voltage characteristic applied between the silicon carbide semiconductor device substrate and the wire, and FIG. 6B shows an image of the surface roughness of the conductive layer obtained as a result. In the present embodiment, the silicon carbide semiconductor device substrate 1d is cut using a wire wire 3a having a diameter of 50 μm and having a pulse voltage of 80 V and a pulse width of 1 μsec (50% duty) as shown in FIG. Under the condition, a pulse voltage of 120 V was applied at a rate of once every three pulses. The feed rate of the wire 3a was 0.5 mm / min.

  FIG. 7 is an AFM (Atomic Force Microscope) image of the surface of the conductive layer formed on the end side surface of the silicon carbide semiconductor element when the silicon carbide semiconductor element is cut from the silicon carbide semiconductor device substrate in the present embodiment. AFM observation of the surface of the conductive layer 17 produced as shown in FIG. 7 was performed to determine the surface roughness (Ra). The surface roughness was about 0.4 μm, and the surface shape changed with a cycle in which the pulse voltage was changed as shown in the image of the surface roughness in FIG. In this embodiment, it has been shown that the surface roughness of the cutting surface is changed by periodically changing the pulse voltage. However, not only the pulse voltage but also the wire wire feed rate, pulse width, duty ratio, etc. are the same. The surface roughness can also be changed by periodically changing to. Further, in the present embodiment, the processing is performed without installing the cooling plate 19 shown in FIG. 4, but the cutting can be similarly performed using the cooling plate 19.

  When a resin film was formed on the surface of the cut silicon carbide Schottky barrier diode, high adhesion was exhibited, and an excellent reliability resin film could be obtained. Various cutting conditions were varied to form cut surfaces with different surface roughnesses, and the adhesion and reliability of the resin film were evaluated. The surface roughness of the conductive layer 17 was set to 0.1 μm or more and 10 μm or less. Sometimes high adhesion and excellent reliability could be obtained. When the surface roughness of the conductive layer 17 was less than 0.1 μm, the surface roughness was small and good adhesion could not be obtained. Also, when the surface roughness exceeds 10 μm, the adhesion of the resin film was relatively sufficient, but the film surface has large irregularities, moisture intrusion etc. from the stepped part, and the reliability cannot be improved. It was.

  1a silicon carbide semiconductor device substrate, 1b silicon carbide semiconductor device substrate, 1c silicon carbide semiconductor device substrate, 1d silicon carbide semiconductor device substrate 2a wire guide, 2b wire guide, 3a wire wire, 3b wire wire, 3c wire wire, 4a stage, 4b stage, 5a stage control unit, 5b stage control unit, 6a machining power source, 6b machining power source, 7a wire control unit, 7b wire control unit, 8a electric discharge machining control unit, 8b electric discharge machining control unit, 9 silicon carbide substrate, 10 epitaxial Silicon carbide layer, 11 Silicon carbide substrate, 12 Ion implantation region, 13 Schottky electrode, 14 Anode electrode, 15 Insulating layer, 16 Cathode electrode, 17 Conductive layer, 18 Semiconductor device, 19 Cooling plate.

A method for manufacturing a silicon carbide semiconductor element of the present invention includes a step of cutting a plurality of semiconductor devices formed on a silicon carbide semiconductor device substrate to form each of them as a silicon carbide semiconductor element, and an end of the silicon carbide semiconductor element. The step of forming a silicon deficient layer having a volume resistivity lower than the volume resistivity of the silicon carbide substrate of the silicon carbide semiconductor device substrate on the side surface is performed in one step using an electric discharge machining method .

Moreover, the silicon carbide semiconductor element of the present invention was subjected to a process of cutting each of a plurality of semiconductor devices formed on the silicon carbide semiconductor device substrate using an electric discharge machining method to form each of them as a silicon carbide semiconductor element. A silicon-deficient layer formed at the same time and having a volume resistivity lower than the volume resistivity of the silicon carbide substrate of the silicon carbide semiconductor device substrate is provided on the end surface.

Claims (13)

  A plurality of semiconductor devices formed on a silicon carbide semiconductor device substrate are cut into respective silicon carbide semiconductor elements by an electric discharge machining method, and volume resistance of a silicon carbide substrate of the silicon carbide semiconductor device substrate is formed on an end side surface of the silicon carbide semiconductor element. The manufacturing method of the silicon carbide semiconductor element including the process of forming the conductive layer which has a volume resistivity lower than a rate.   The method for manufacturing a silicon carbide semiconductor element according to claim 1, wherein the volume resistivity of the conductive layer formed on the side surface of the silicon carbide semiconductor element in the step is 7 Ωcm or less.   2. The method for manufacturing a silicon carbide semiconductor element according to claim 1, wherein a thickness of the conductive layer formed on the end side surface of the silicon carbide semiconductor element in the step is 10 μm or more and 20 μm or less.   The method for manufacturing a silicon carbide semiconductor element according to claim 1, wherein the crystallinity of the conductive layer formed on the side surface of the silicon carbide semiconductor element in the step is lower than the crystallinity of the silicon carbide substrate.   2. The method for manufacturing a silicon carbide semiconductor device according to claim 1, wherein the surface roughness of the conductive layer formed on the end side surface of the silicon carbide semiconductor device in the step is 0.1 μm or more and 10 μm or less.   The method for manufacturing a silicon carbide semiconductor element according to claim 1, wherein the conductive layer formed on the end side surface of the silicon carbide semiconductor element is a silicon-deficient layer.   The method for manufacturing a silicon carbide semiconductor element according to claim 1, wherein a cooling mechanism is provided on a surface of the silicon carbide semiconductor device substrate in the electric discharge machining method.   A silicon carbide semiconductor element comprising a silicon deficient layer having a volume resistivity lower than a volume resistivity of a silicon carbide substrate on an end side surface.   The silicon carbide semiconductor device according to claim 8, wherein the volume resistivity of the silicon-deficient layer is 7 Ωcm or less.   The silicon carbide semiconductor element according to claim 8, wherein the silicon-deficient layer has a thickness of 10 μm or more and 20 μm or less.   The silicon carbide semiconductor element according to claim 8, wherein the crystallinity of the silicon-deficient layer is lower than the crystallinity of the silicon carbide substrate.   The silicon carbide semiconductor element according to claim 8, wherein a surface roughness of the silicon-deficient layer is 0.1 μm or more and 10 μm or less.   The silicon carbide semiconductor module using the silicon carbide semiconductor element of any one of Claims 8 thru | or 12.

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