Composite semiconductor device, method for its manufacture and resin-sealed semiconductor device

Abstract

Composite semiconductor device comprising: a substrate (1); an aluminium nitride layer arranged over the substrate (1); a composite semiconductor layer arranged above the aluminium nitride layer; and wherein part of one side of the substrate (1), one side of the aluminium nitride layer and one side of the composite semiconductor layer form a continuous inclined surface, and an end surface of the substrate (1) is perpendicular to an upper surface of the substrate (1), wherein the continuous inclined surface of the substrate (1) is connected to the end surface of the substrate (1), and an amorphous layer or a polycrystalline layer (13) is formed in contact with the continuous inclined surface of the aluminium nitride layer, and wherein the amorphous layer or the polycrystalline layer (13) has peaks and valleys with a mean spacing of 0.05 µm to 1.0 µm on a surface of the amorphous layer or the polycrystalline layer (13).

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present disclosure relates to a composite semiconductor device in which a composite semiconductor layer, which is epitaxially grown on a silicon substrate, is formed over a buffer layer consisting of aluminium nitride, as well as to a method for its fabrication and a resin-sealed semiconductor device. 2. Description of the state of the art

[0002] In recent years, the development of a nitride-based semiconductor material, which is a wide-bandgap semiconductor, has been actively pursued as a material for semiconductor devices. A characteristic feature of wide-bandgap semiconductors is that they exhibit an insulation breakdown voltage that is an order of magnitude higher than that of silicon (Si), a more common semiconductor.

[0003] In conventional silicon, a long drift layer, in which electrons move, is required to obtain a power semiconductor device with a high breakdown voltage. In contrast, gallium nitride (GaN) achieves an equivalent breakdown voltage with a short drift layer (about 1 / 10 that of Si). In this case, when considering a situation where an electric current will flow in the semiconductor device, the drift layer becomes a resistive layer, so the on-resistance of the semiconductor device decreases when the drift layer is shorter. Theoretically, assuming that the mobility and dielectric constant of a semiconductor are of the same degree, the on-resistance of a semiconductor device exhibiting a given predetermined breakdown voltage is inversely proportional to the cube of the electrical insulation breakdown field of the semiconductor material.In other words, with the same chip area, an on-resistance that is about 1 / 1000 lower can be achieved in a GaN device compared to a Si device.

[0004] A nitride-based semiconductor material can form various mixed crystals with GaN, aluminum nitride (AlN), and indium nitride (InN), allowing the nitride semiconductor to create a heterojunction similar to that of a conventional arsenic semiconductor such as gallium arsenic (GaAs). In particular, the heterojunction of the nitride-based semiconductor exhibits a characteristic feature: a high charge carrier concentration at the interface is generated through spontaneous polarization or piezopolarization, even in the absence of impurity doping. Consequently, in a lateral-type device where an electric current flows in a direction parallel to the silicon substrate, the GaN / AlGaN heterojunction enables the creation of a high-power device with low on-resistance and high current capability.

[0005] Furthermore, the nitride-based semiconductor material can be epitaxially grown on a silicon substrate via a buffer layer consisting of aluminum nitride. In other words, while it is necessary to use an expensive silicon carbide substrate (SiC substrate) with the same wide-bandgap semiconductor material in the case of a SiC device, it is possible to use a silicon substrate in the case of a nitride-based semiconductor device, thus achieving a reduction in cost and an increase in diameter.

[0006] Meanwhile, the nitride-based semiconductor device, in which the nitride-based semiconductor layer has been formed on the silicon substrate (wafer), is divided into semiconductor devices by performing a separation along a scribed track, as in a conventional silicon or GaAs device. In this separation step, after the wafer is adhered to a separating tape, the wafer undergoes a cutting process along the scribed track while a thin-type grinding wheel with a disc shape, known as a separating blade, is rotated at high speed.

[0007] In this cutting step, fragmentation, cracks, and crystal defects of the semiconductor layer, called splinters, are generated in the scribble track if the blade type, rotational speed, cutting rate, and the like are not appropriately selected. Furthermore, if the splinters or crystal defects generated in the scribble track reach an element formation area within the semiconductor device, a deficiency in electrical properties or a lack of reliability caused by moisture ingress will occur.

[0008] Generally, the blade type, rotational speed, and cutting rate are selected to eliminate defect generation in the semiconductor device caused by chipping or crystal defects. A scribing width is set such that the defect remains within the scribing path, even if chipping or crystal defects are generated, or if moisture penetrates the buffer layer.

[0009] In silicon devices, a structure for suppressing chipping in semiconductor devices is known. PTL 1, for example, discloses a structure in which a film is formed on a scribing track between several semiconductor elements formed on a semiconductor wafer. According to this structure, the propagation of a stress that induces chipping can be absorbed or attenuated by a wall of this film, thus suppressing chipping.

[0010] On the other hand, a structure in which an aluminum nitride layer is formed as a surface protection film is known in a nitride-based composite semiconductor device. PTL 2, for example, discloses a structure in which an AlN layer is formed as a surface protection film on the top surface of an AlGaN layer. According to this manufacturing process, the top surface of the AlGaN layer is covered with the AlN layer before cracks are generated, so that the surface can be expected to be flat and free of cracks. List of prior art patent literature PTL 1: Unaudited Japanese Disclosure Document JP 2006 - 302 939 A PTL 2: Unaudited Japanese Disclosure Document JP 2006 - 156 429 A

[0011] In a nitride-based semiconductor device with a nitride-based semiconductor layer epitaxially grown on a silicon substrate, splintering or crystal defects are likely to be generated at the end of the nitride-based composite semiconductor to a greater degree than in the silicon or GaAs device when the nitride-based semiconductor layer is subjected to cleavage. Therefore, there are cases where the generation of a deficiency and degradation of reliability caused by splintering or crystal defects cannot be sufficiently suppressed by a general procedure such as the one described above. The reason for this is as follows: Due to the difference in lattice constant and coefficient of thermal expansion between silicon and the nitride-based semiconductor, such as GaN, a large stress is generated near an interface between the silicon substrate and the nitride-based semiconductor layer.If a mechanical shock is applied near the interface between the silicon substrate and the nitride-based semiconductor layer at the time of separation, cracks and crystal defects are created, with this interface serving as the starting point.

[0012] Furthermore, the greater the thickness of the epitaxially grown nitride-based semiconductor layer, the greater the voltage. Consequently, the number of locations where chips or crystal defects are generated increases, and the size of the chips or crystal defects also increases.

[0013] Fig. Figure 5 shows a schematic top view when a nitride-based semiconductor layer grown epitaxially on a silicon substrate is subjected to separation. Fig. 5. A large number of tiny fragments are generated along the severance line. Among these, some fragments are generated that extend beyond the scoring line and reach the surface protective film of the element, as shown in Fig. Figure 6 shows that in this case, the appearance of the semiconductor device is also defective.

[0014] The buffer layer aluminum nitride used in the epitaxial growth of the nitride-based semiconductor layer on the silicon substrate reacts with moisture, resulting in the reaction AlN + 3H2O → Al(OH)3 + NH3. This causes a problem insofar as the properties are degraded by the moisture or dampness penetrating through the end of the element.

[0015] In the case of sealing the nitride-based semiconductor element with a resin (including the cases of "integration into a component-integrated substrate" and "under / side filling sealing of flip-chip assembly"), problems arise insofar as flaking occurs at the interface with the sealing resin due to the exposure of the nitride-based semiconductor epitaxy film, which has poor dense adhesion to the resin, at the end of the element.

[0016] In a nitride-based semiconductor device with a nitride-based semiconductor layer grown epitaxially on a silicon substrate, consideration can be given to preventing chipping, crystal defects, or moisture penetration into the semiconductor element from reaching an active region of the element by further specifying the scribble width to approximately 150 µm. However, increasing the scribble width reduces the number of chips that can be produced from a single wafer area.

[0017] A method for removing the nitride-based semiconductor layer in the scribe track by dry etching or similar means before the scribe track is cut can be considered. However, to achieve an element with a high breakdown voltage of at least 500 V, the thickness of the high-resistance nitride-based semiconductor layer grown on the electrically conductive silicon substrate must be at least 4 µm, making it difficult to remove such a thick nitride-based semiconductor layer by etching.

[0018] Furthermore, US 2009 / 0166678 A1 discloses a semiconductor device comprising a substrate having on its main surface a central area and a peripheral area surrounding and exposed the central area, a semiconductor layer formed on the main surface of the substrate, made of a material harder than the substrate, having the shape of a mesa and a steep side above the exposed peripheral area, and an insulating film provided on a side surface of the semiconductor layer.

[0019] US 2013 / 0234149 A1 deals with the manufacture of a light-emitting diode using a laser to texture the sidewalls of the lower contact layer without damaging a mesa.

[0020] Furthermore, US patent 2007 / 0102693 A1 discloses an LED array chip in which LEDs are connected in series via a wire bridge. Each LED has a multilayer semiconductor structure with a light-emitting layer epitaxially grown on a front surface of a SiC substrate. The power supply connection is made to a cathode electrode of an LED at a lower potential end and to an anode electrode of an LED at a higher potential end, each via a wire bridge and a plated through-hole. SUMMARY OF THE INVENTION

[0021] The present disclosure was carried out in view of such circumstances and one object of it is to provide a semiconductor device with a nitride-based semiconductor layer epitaxially grown on the surface side of a silicon substrate or the like, wherein the semiconductor device has a structure in which the chipping and crystal defects produced at the time of separation can be suppressed even if the scribble track width is not set large, or if the nitride-based semiconductor layer is not etched by the scribble track, and in which the aluminum nitride is not exposed at the end of the element.

[0022] To solve the aforementioned problems, a composite semiconductor device according to the disclosure of the present application is a composite semiconductor device comprising a composite semiconductor chip with a composite semiconductor layer epitaxially grown on a substrate over an aluminum nitride layer, wherein the aluminum nitride layer, which is arranged under the composite semiconductor layer around the circumference of an element, is covered with an amorphous layer or a polycrystal layer.

[0023] This enables the suppression of chipping, crystal defects, and moisture penetration in a semiconductor device featuring a nitride-based semiconductor layer epitaxially grown on a silicon substrate and scribed along the scribble track. In other words, if chipping, crystal defects, and moisture penetration generated from the scribbled surface propagate along the scribble track, a chip-suppression structure formed at the end of the nitride-based semiconductor layer in the scribble track suppresses this propagation.

[0024] The nitride-based composite semiconductor device, the method for its production, and the resin-sealed semiconductor device according to the disclosure of the present application provide an advantage such that, when the splintering, crystal defects, and moisture penetration generated by the separation surface separated along the scribble track spread, a structural body for suppressing the splintering, crystal defects, and moisture penetration, formed at the end of the nitride-based semiconductor layer in the scribble track, can suppress this spread of the splintering, crystal defects, and the like. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a top view of a semiconductor device according to an exemplary embodiment; Fig. Figure 2A is a schematic view showing a semiconductor wafer before and after separation, in which several semiconductor devices are arranged according to an exemplary embodiment; Fig. Figure 2B is a schematic view showing a semiconductor wafer before and after separation, in which several semiconductor devices are arranged according to an exemplary embodiment; Fig. Figure 2C is a schematic view showing a semiconductor wafer before and after separation, in which several semiconductor devices are arranged according to an exemplary embodiment; Fig. 3A is a view showing a photograph of a cross-section around a scoring track before cutting; Fig. 3B is a view showing an enlarged photograph of a sectioned surface after the scoring line of Fig. 3A was cut with a blade; Fig. Figure 4A is a view showing a photograph of a cross-section around a scribble path in which structural bodies for suppressing chipping, crystal defects and moisture penetration were formed by fusion, reaction and production of an amorphous state down to a silicon substrate using a laser beam; Fig. 4B is a view showing the result of an elemental analysis around a scribble path in which structural bodies were formed to suppress chipping, crystal defects and moisture penetration by fusion, reaction and production of an amorphous state up to a silicon substrate using a laser beam; Fig. 4C is a view showing a photograph of a cross-section around a scribing track in which structural bodies for suppressing chipping, crystal defects and moisture penetration were formed by fusion, reaction and production of an amorphous state to a silicon substrate using a laser beam; Fig. 4D is a view showing the result of an elemental analysis around a scribble path in which structural bodies were formed to suppress chipping, crystal defects and moisture penetration by fusion, reaction and creating an amorphous state up to a silicon substrate using a laser beam; Fig. Figure 4E is a view showing a photograph of a cross-section around a scribing track in which structural bodies for suppressing chipping, crystal defects and moisture penetration were formed by fusion, reaction and production of an amorphous state to a silicon substrate using a laser beam; Fig. 4F is a view showing the result of an elemental analysis around a scribble path in which structural bodies were formed to suppress chipping, crystal defects and moisture penetration by fusion, reaction and production of an amorphous state up to a silicon substrate using a laser beam; Fig. 4G is a view showing a photograph of a cross-section around a scribble path in which structural bodies for suppressing chipping, crystal defects and moisture penetration were formed by fusion, reaction and production of an amorphous state to a silicon substrate using a laser beam; Fig. 4H is a view showing the result of an elemental analysis around a scribble path in which structural bodies were formed to suppress chipping, crystal defects and moisture penetration by fusion, reaction and production of an amorphous state up to a silicon substrate using a laser beam; Fig. 5 is a schematic top view after a conventional semiconductor device with a nitride-based semiconductor layer has been formed by separation; and Fig. Figure 6 is a schematic top view showing a defect caused by chipping created in a conventional semiconductor device with a nitride-based semiconductor layer. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0025] Exemplary embodiments of a composite semiconductor device according to the disclosure of the present application, a method for manufacturing the same and a resin-sealed semiconductor device are described below with reference to the accompanying drawings.

[0026] Fig. Figure 1 is a top view of a semiconductor device according to the present exemplary embodiment. This semiconductor device was produced by cutting a semiconductor wafer in which several semiconductor devices are arranged.

[0027] Fig. 2A, Fig. 2B and Fig. Figures 2C are cross-sectional views, each showing the semiconductor wafer before and after separation, in which several of the Fig. Semiconductor devices shown in 1 are arranged, with a nearby scribing track 10 being shown. With reference to Fig. 2A, Fig. 2B and Fig. In the semiconductor device 2C, a nitride-based semiconductor layer 2 with a buffer layer is arranged over the entire surface of the silicon substrate 1. In the present exemplary embodiment, the substrate is silicon; however, the substrate can be any silicon, sapphire, or silicon carbide. On the silicon substrate 1, a nitride-based semiconductor layer 2 is formed such that it extends over a semiconductor element formation area and a scribble track 10. The nitride-based semiconductor layer 2 is a layer formed by epitaxial growth of a nitride-based semiconductor on the silicon substrate 1. Here, in a rectangular semiconductor element area, the nitride-based semiconductor layer 2 comprises a buffer layer consisting of AlN or AlGaN, an operational layer consisting of GaN or AlGaN, and the like.

[0028] Furthermore, with regard to Fig. 1, Fig. 2A, Fig. 2B and Fig. 2C A surface protection film 3 is arranged in the rectangular semiconductor element area on the surface of the nitride-based semiconductor layer 2. The surface protection film 3 consists, for example, of SiN and is formed by plasma-CVD (chemical vapor deposition). A scribble track 10 is provided around the perimeter of the semiconductor device such that it surrounds this semiconductor element area. Furthermore, with reference to Fig. 1 A first contact point 21, a second contact point 22, and a comb-shaped connection 23 with a common compound metal layer 4 are formed on the surface protective film 3 in the semiconductor element area. The compound metal layer 4 has a structure in which a Ti layer 4a and an Au layer 4b (not shown) are stacked, and the Au layer 4b was formed by plating onto the Ti layer 4a.

[0029] The thickness of each layer is such that, for example, the thickness of the Ti layer 4a is 0.1 µm and the thickness of the Au layer 4b is 5 µm. The Ti layer 4a, which is a lower layer, exhibits good dense adhesion to the nitride-based semiconductor layer 2 and serves to enhance the dense adhesion between the Au layer 4b and the nitride-based semiconductor layer 2.

[0030] A portion of the nitride-based semiconductor layer 2 is located within an annular scribble track 10 that exists around the circumference of the semiconductor device. With reference to Fig. 2A, Fig. 2B and Fig. 2C are a first structural body 11, a second structural body 12, a third structural body 13 and a fourth structural body 14, which suppress chipping, crystal defects and moisture penetration, formed on the portion of the nitride-based semiconductor layer 2 that is present in the scribble track 2. With reference to Fig. The first structural body 11, the second structural body 12, the third structural body 13, and the fourth structural body 14, which suppress chipping, crystal defects, and moisture penetration, are formed along the scribble track 10. In other words, the first structural body 11, the second structural body 12, the third structural body 13, and the fourth structural body 14, which suppress chipping, crystal defects, and moisture penetration, are formed in a ring shape around the circumference of the semiconductor device. The first structural body 11 creates a protective film effect over the entire buffer layer, which makes contact with the silicon substrate 1 by extending widely around a center point of the scribble track where a cutting blade comes into contact.The second structural body 12 is formed by re-adhesion after being spread by a laser beam ablation phenomenon and covers a portion of the area from around the center of the scribe path to a region where the buffer layer is not exposed at one end. The third structural body 13 protects the buffer layer against moisture and wetness by covering the end of the buffer layer. The fourth structural body 14 is formed on the surface of an area remaining at the end of the chip after separation and improves the tight adhesion at the interface with a sealing resin in the case of sealing with the resin (including the cases of "integration into a component-integrated substrate" and "under / side-fill sealing of flip-chip assembly").The structures of the first structural body 11, the second structural body 12, the third structural body 13 and the fourth structural body 14, which suppress chipping, crystal defects and moisture penetration, are produced by the first structural body 11, which is a groove / recess reaching the silicon substrate 1, the second structural body 12, which is an area obtained by partially amorphizing the nitride-based composite semiconductor layer, the third structural body 13, which is a coating film to protect the aluminum nitride barrier layer against moisture and wetness, and the fourth structural body 14, which is a nitride-based composite semiconductor layer obtained by surface roughening (0.05 µm to 1.0 µm) (see . Fig. 2A, Fig. 2B and Fig. 2C). Here, the first structural body 11, the second structural body 12, the third structural body 13, and the fourth structural body 14, which suppress chipping, crystal defects, and moisture penetration, can be formed in a continuous ring shape along the annular scoring track 10; with reference to Fig. However, the first structure body 11, the second structure body 12, the third structure body 13, and the fourth structure body 14 can be separated at a corner part or the like of the semiconductor device. A splinter suppression effect is generated even if the width of the first structure body 11, the second structure body 12, the third structure body 13, and the fourth structure body 14, which suppress splintering, crystal defects, and moisture penetration, is small; however, the effect is greater if the width is larger. The scribble width, however, is large if the width of the first structure body 11, the second structure body 12, the third structure body 13, and the fourth structure body 14, which suppress splintering, crystal defects, and moisture penetration, is set too large.The width of the first structural body 11, the second structural body 12, the third structural body 13 and the fourth structural body 14, which suppress chipping, crystal defects and moisture penetration, is suitably 5 µm to 25 µm, preferably 10 µm to 20 µm.

[0031] Next, a separation step is described which is a characteristic step in the process for manufacturing a composite semiconductor device according to the disclosure of the present application.

[0032] The in Fig. The semiconductor device shown in 1 is created by separating the in Fig. 2A, Fig. 2B and Fig. The semiconductor wafer shown in Figure 2C is prepared along the scribble track 10 and subdivided. The separation step is carried out as follows: after the semiconductor wafer is adhered to a separation tape, the scribble track 10 is brought adjacent to the nitride-based semiconductor layer 2, and the semiconductor wafer is subjected to a cutting process by moving the semiconductor wafer in a forward and backward direction on a sheet of paper. Fig. 2A, Fig. 2B and Fig. The material is subjected to 2C while a thin-type grinding wheel with a disc shape, known as a separating blade, is rotated at high speed. In this separating step, the type of blade to be used, the rotational speed, the separating rate, and the like are appropriately determined. The blade width of the separating blade is approximately 20 µm to 30 µm, and the width of the scoring track 10, which is defined in the semiconductor wafer, is approximately 50 µm to 100 µm.

[0033] Next, with regard to means, a mechanism and the like to ensure stable quality in the separation step, the effect of suppressing splintering, crystal defects and the like by the first structural body 11, the second structural body 12, the third structural body 13 and the fourth structural body 14, which suppress splintering, crystal defects and moisture penetration, that is, the effect of suppressing splintering, crystal defects and the like, in the nitride-based semiconductor device with the above configuration is described.

[0034] In the semiconductor device described above, the nitride-based semiconductor layer 2 is configured to extend across the semiconductor cell formation area and the scribble track 10 on the silicon substrate 1. Therefore, when chipping, crystal defects, and the like are generated from a separation surface during the separation of the nitride-based semiconductor layer 2 and the silicon substrate 1 along the scribble track 10, the chipping, crystal defects, and the like propagate to the semiconductor cell formation area.However, since the first structural body 11, the second structural body 12, the third structural body 13 and the fourth structural body 14, which suppress chipping, crystal defects and moisture penetration, are formed on the nitride-based semiconductor layer 2 in the scribble track 10, the progression of chipping, crystal defects and the like is prevented by the first structural body 11, the second structural body 12, the third structural body 13 and the fourth structural body 14, which suppress chipping, crystal defects and moisture penetration.

[0035] The first structural body 11, the second structural body 12, the third structural body 13, and the fourth structural body 14, which suppress chipping, crystal defects, and moisture penetration, feature a groove / recess that reaches the silicon substrate 1, even though they are formed at one end of the nitride-based semiconductor layer. This reduces the likelihood of damage propagating to the nitride-based semiconductor layer at the time of separation, thus significantly increasing the effect of suppressing chipping, crystal defects, and moisture penetration. Therefore, the propagation of chipping, crystal defects, and the like to one side of the semiconductor element can be sufficiently suppressed.

[0036] The first structural body 11, the second structural body 12, the third structural body 13 and the fourth structural body 14, which suppress chipping, crystal defects and moisture penetration, are further formed in a line shape along a boundary between the semiconductor element formation area and the scribble track, so that the effect of preventing chipping, crystal defects and the like can be sufficiently maintained while keeping the width of the scribble track 10 small.

[0037] Next, a method for emitting a laser beam onto the scribble track 10, on which a nitride-based semiconductor film has been formed (where the film thickness is 4 µm), is described.

[0038] First, a water-soluble protective film is applied by rotation to a wafer in a state where the surface protective film 3 has been formed on a nitride-based semiconductor, and then a laser beam is emitted along the scribble path 10. In the present exemplary embodiment, the laser beam is allowed to scan in a direction perpendicular to a (111) plane of the silicon substrate 1; however, it is possible for the laser beam to scan in other directions. During this process, the first structural body 11, the second structural body 12, the third structural body 13, and the fourth structural body 14, which suppress chipping, crystal defects, and moisture penetration, can be formed to have a large width if the laser beam is allowed to scan multiple times while a position of the laser beam is successively shifted along the scribble path.For example, if the processing width per single laser scan is set to 10 µm to 30 µm and the position is shifted from outside the scribing path towards a center with a displacement of 5 µm to 20 µm, then a final processing width of 40 µm to 90 µm can be achieved by multiple scans. Laser beam conditions during this process are set such that, with fixed power control, the pulse frequency is 40 kHz to 100 kHz; the output power is 2 W to 7 W; the transmission speed is 100 mm / s to 400 mm / s; and the laser focal point is located between a work surface and a point 0.2 mm above it. Afterwards, a spread substance adhering to an active area, along with the water-soluble protective film, can be removed by washing the wafer surface with pure water.Since the water-soluble protective film at one end of the chip has been removed by the laser beam at this point, the spread substance can be selectively retained as a protective film only at that end. Because the spread substance is dispersed by an ablation phenomenon with the laser beam and cooled within a short time, it becomes an amorphous layer or a polycrystalline layer with peaks and valleys spaced 0.05 µm to 1.0 µm apart on its surface. Subsequently, the scriber track 10 is positioned adjacent to the nitride-based semiconductor layer 2, and the wafer is subjected to a cutting process by moving the wafer forward and backward in a paper-like motion. Fig. 2A, Fig. 2B and Fig. The process is subjected to 2C while a thin-type grinding wheel with a disc shape, known as a separating blade, is rotated at high speed. The blade width of the separating blade is approximately 20 µm to 30 µm, and the width of the scoring track 10, which is defined in the semiconductor wafer, is approximately 50 µm to 100 µm.

[0039] The composite semiconductor device of the present exemplary embodiment is a composite semiconductor device in which the amorphous layer or the polycrystalline layer contains at least silicon or aluminum, or both silicon and aluminum. Since either silicon or aluminum has a property that it is less likely to penetrate to a deep part, even when reacting with moisture, the amorphous layer or the polycrystalline layer therefore produces an effect of protecting the buffer layer aluminum nitride against moisture.

[0040] The composite semiconductor device of the present exemplary embodiment is a composite semiconductor device in which the amorphous layer or the polycrystalline layer contains silicon with not less than 1 at%. Since a material containing silicon with more than 1 at% has the further improved property of being less likely to propagate to the deep part, even when reacting with moisture, the amorphous layer or the polycrystalline layer therefore produces a further improved effect of protecting the buffer layer aluminum nitride against moisture.

[0041] Fig. 3A and Fig. 3B are views, each showing a photograph of a cross-section around a scribble track 10 in which the first structural body 11, the second structural body 12, the third structural body 13 and the fourth structural body 14, which suppress chipping, crystal defects and moisture penetration, have been formed. Fig. 3A is a view showing a photograph of a cross-section around a scoring track 10 before cutting, and Fig. 3B is a view showing an enlarged photograph of a sectioned surface after the scoring line 10 of Fig. 3A shows that it was cut with a blade.

[0042] Fig. 4A, Fig. 4C, Fig. 4E and Fig. 4G are views that each show a photograph of a cross-section around a scribble path in which structural bodies for suppressing chipping, crystal defects and moisture penetration were formed by fusion, reaction and production of an amorphous state to silicon substrate 1 using a laser beam. Fig. 4B, Fig. 4D, Fig. 4F and Fig. 4H are views, each showing a result of an elemental analysis around a scribble path in which structural bodies for suppressing chipping, crystal defects, and moisture penetration were formed by fusion, reaction, and the creation of an amorphous state up to silicon substrate 1 using a laser beam. A second spectrum, which is shown in Fig. 4A and Fig. 4B is shown, and a third spectrum, which is in Fig. 4E and Fig. Figure 4F shows elemental analysis data (EDX method (energy-dispersive X-ray method)) of the second structural body 12 and the third structural body 13. A first spectrum, which is shown in Fig. 4C and Fig. The 4D image shows elemental analysis data (EDX method) of a nitride-based semiconductor layer 2. A Fig. 4G and Fig.The fourth spectrum shown in Figure 4H displays elemental analysis data (EDX method) of silicon substrate 1. From the second and third spectra, it is evident that the second structural body 12 and the third structural body 13 contain silicon and aluminum. In the present data, silicon is also a major constituent element, with the second spectrum showing 25.57 at% and the third spectrum showing 81.35 at%.

[0043] In the present exemplary embodiment, an example using a silicon substrate 1 has been described. However, even when using a sapphire or silicon carbide substrate, a large stress is generated due to the difference in the lattice constant or the coefficient of thermal expansion when a nitride-based semiconductor layer is grown on the substrate. Therefore, even when using such a substrate, a similar effect can be obtained by forming the first structural body 11, the second structural body 12, the third structural body 13, and the fourth structural body 14, which suppress chipping, crystal defects, and moisture penetration along the scribe path, in the same manner as in the exemplary embodiment described above.

[0044] At the time of fusion, reaction and the production of an amorphous state up to silicon substrate 1 using a laser beam, a protective coating film can be formed simultaneously at the end of the aluminum nitride layer if conditions are selected to allow the protective coating film to adhere again at the end of the aluminum nitride layer by the ablation phenomenon (triple YAG laser (where the wavelength of the laser beam is 355 nm)), thereby minimizing the increase in the number of manufacturing steps and the increase in production costs.

[0045] The nitride-based semiconductor layer of the composite semiconductor device according to the disclosure of the present application can be configured to extend over the semiconductor element formation area and the scribble track on the silicon substrate 1. This enables chipping, crystal defects, and the like to be effectively prevented by the structural elements, which suppress chipping, crystal defects, and moisture penetration.

[0046] The structural elements that suppress chipping, crystal defects, and moisture penetration are preferably formed in a linear configuration along a boundary between the semiconductor element formation area and the scribble track. This allows chipping, crystal defects, and the like to be prevented while keeping the width of the scribble track small.

[0047] The above structural bodies, which suppress chipping, crystal defects and moisture penetration, can also have a configuration with an area that has been converted to amorphous, with a protective coating film at the end of the aluminum nitride layer, or with an area obtained by surface roughening (0.05 µm to 1.0 µm) of the nitride-based composite semiconductor.

[0048] The above structural bodies, which suppress splintering, crystal defects and moisture penetration, can produce similar effects when an area is formed by fusion, reaction and the creation of an amorphous state down to the silicon substrate 1 using a laser beam.

[0049] The above structural bodies, which suppress chipping, crystal defects and moisture penetration, can themselves produce similar effects by allowing a compound with a similar effect to re-adhere to a sidewall using a plasma etching process.

[0050] The structural bodies that suppress chipping, crystal defects and moisture penetration, although formed at the end of the nitride-based semiconductor layer, have a groove / recess that reaches the silicon substrate 1, so that damage at the time of separation is less likely to propagate to the nitride-based semiconductor layer, and the effect of the function of suppressing chipping, crystal defects and moisture penetration is large.

[0051] Even if chipping, crystal defects, and the like are generated near the interface between the substrate and the nitride-based semiconductor layer, this prevents the chipping, crystal defects, and the like from propagating towards the semiconductor element side, thus eliminating the electrical deficiency of the semiconductor element in the semiconductor device. Simultaneously, the reliability and yield of the semiconductor device are improved. Since there is no need to specify a large scribe width, the number of semiconductor devices per wafer can be ensured.

[0052] The nitride-based composite semiconductor device, the method for its fabrication, and the resin-sealed semiconductor device according to the disclosure of the present application provide an advantage such that, even when a semiconductor device in which a nitride-based semiconductor layer is formed on a semiconductor wafer such as a silicon substrate is used, chipping, crystal defects, and moisture in the separation step can be prevented from reaching the active area of ​​the element without increasing the width of the scribble path, thereby ensuring the electrical properties and reliability of the semiconductor device.

[0053] Therefore, the present disclosure provides a technique that is useful in achieving a semiconductor device for electrical power that exhibits a high breakdown voltage.

Claims

[1] Composite semiconductor device comprising: a substrate (1); an aluminium nitride layer arranged over the substrate (1); a composite semiconductor layer arranged above the aluminium nitride layer; and wherein part of one side of the substrate (1), one side of the aluminium nitride layer and one side of the composite semiconductor layer form a continuous inclined surface, and an end surface of the substrate (1) is perpendicular to an upper surface of the substrate (1), wherein the continuous inclined surface of the substrate (1) is connected to the end surface of the substrate (1), and an amorphous layer or a polycrystalline layer (13) is formed in contact with the continuous inclined surface of the aluminium nitride layer, and wherein the amorphous layer or the polycrystalline layer (13) has peaks and valleys with a mean spacing of 0.05 µm to 1.0 µm on a surface of the amorphous layer or the polycrystalline layer (13). [2] Composite semiconductor device according to claim 1, configured for use in an electrical power device. [3] Composite semiconductor device according to claim 1, wherein a compound metal layer (4) is formed above the composite semiconductor layer. [4] Composite semiconductor device according to claim 1, wherein a semiconductor element is formed above the composite semiconductor layer. [5] Composite semiconductor device according to claim 1, wherein the entire side of the composite semiconductor layer forms part of the continuous inclined surface. [6] Composite semiconductor device according to any one of claims 1 to 4, wherein the substrate (1) consists of any silicon, silicon carbide and sapphire. [7] Semiconductor device of a resin-sealed type, wherein the amorphous layer or the polycrystal layer (13) of the composite semiconductor device according to any one of claims 1 to 4 is in contact with a resin medium for assembly, so that one of these layers is underfilled or sidefilled by mold resin sealing, integration into a component-integrated substrate or flip-chip assembly. [8] Composite semiconductor device according to claim 1, wherein the amorphous layer or a polycrystalline layer (13) is formed by laser irradiation. [9] Composite semiconductor device according to claim 1, wherein the amorphous layer or the polycrystal layer (13) contains silicon and / or aluminium. [10] Composite semiconductor device according to claim 1, wherein the amorphous layer or the polycrystal layer (13) contains silicon with not less than 1 at-%. [11] Composite semiconductor device comprising: a substrate (1); an aluminium nitride layer arranged over the substrate (1); a composite semiconductor layer arranged above the aluminium nitride layer; wherein part of one side of the substrate (1), one side of the aluminium nitride layer and one side of the composite semiconductor layer form a continuous inclined surface, an end surface of the substrate (1) is perpendicular to an upper surface of the substrate (1), wherein the continuous inclined surface of the substrate (1) extends to the end surface of the substrate (1), and an amorphous layer or a polycrystalline layer (13) is formed in contact with the continuous inclined surface of the substrate (1) and the side of the aluminium nitride layer. [12] Composite semiconductor device according to claim 11, configured for use in an electrical power device. [13] Composite semiconductor device according to claim 11, wherein a compound metal layer (4) is formed above the composite semiconductor layer. [14] Composite semiconductor device according to claim 11, wherein a semiconductor element is formed above the composite semiconductor layer. [15] Composite semiconductor device according to claim 11, wherein the entire side of the composite semiconductor layer forms the continuous inclined surface. [16] Composite semiconductor device according to any one of claims 11 to 14, wherein the substrate (1) consists of any silicon, silicon carbide and sapphire. [17] Semiconductor device of a resin-sealed type, wherein the amorphous layer or the polycrystal layer (13) of the composite semiconductor device according to any one of claims 11 to 14 is in contact with a resin medium for assembly, so that one of these layers is underfilled or sidefilled by mold resin sealing, integration into a component-integrated substrate or flip-chip assembly.

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