JP2009289965A - Gallium nitride semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gallium nitride semiconductor device in which incident light and emitting light are not obstructed by the wirings between electrodes, the semiconductor device having many GaN light emitting elements or GaN light receiving elements formed 2 dimensionally. <P>SOLUTION: A mask 11 for selective growth is formed on a substrate 1 for growth, and an AlN buffer layer 2 is formed in the area where a part of the mask 11 for selective growth is removed. On the AlN buffer layer 2, an undoped GaN layer 3, an n-type GaN layer 4, an active layer 5 and a p-type GaN layer 6 are sequentially laminated and a separation groove A for separating between the elements is formed. A p-side transparent electrode 8 and n electrode 7 of respective GaN semiconductor elements D are formed on a light take-out face or a light receiving face for the semiconductor element D. Part of the wirings 12, 13 connecting respective electrodes are composed of the same material of the p-side transparent electrode 8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a GaN-based semiconductor device in which a large number of GaN-based semiconductor light-emitting elements or semiconductor light-receiving elements are two-dimensionally formed.

  Conventionally, a semiconductor light emitting device or a semiconductor light receiving device formed by laminating a plurality of compound semiconductor layers on a substrate is known. As a typical semiconductor light emitting device, an LED (Light Emitting Diode), a semiconductor laser, and the like are known. For example, an LED forms a pn or pin junction of a compound semiconductor (GaAs, GaP, AlGaAs, etc.), applies a forward voltage to the junction, injects carriers into the junction, and emits light during the recombination process. Is used. Conventionally, such an LED is obtained by using a liquid phase epitaxy (LPE) method, a metal organic chemical vapor deposition (MOCVD) method, and a compound semiconductor lattice-matched to each substrate such as GaAs, AlGaAs, InP, and InGaAsP on a single crystal substrate such as GaAs or InP. It is manufactured by performing epitaxial growth using a crystal growth method such as the VPE method, VPE (vapor phase epitaxy) method, MBE (molecular beam epitaxy) method, etc., and processing.

  In recent years, nitride semiconductors have been used for blue LEDs used as light sources for lighting, backlights, etc., LEDs used for multi-coloring, LDs, and the like. In a nitride semiconductor light emitting device, a pn or pin junction is formed on a substrate such as a sapphire substrate using MOCVD or the like. On the other hand, a semiconductor light receiving element such as a photodiode that receives light in a blue or ultraviolet region is manufactured using a nitride semiconductor.

A semiconductor device has been proposed in which a large number of semiconductor elements as described above are formed on a common substrate and the semiconductor elements are arranged in an array. For example, Patent Document 1 describes a light-emitting device using a nitride semiconductor as an example of the semiconductor device.
JP 2004-6582 A

  As shown in Patent Document 1, since each semiconductor light emitting element usually has a p-type GaN layer upper surface as a light extraction surface, a p-type transparent electrode is formed on the p-type GaN layer. And electrodes of other semiconductor light emitting elements are connected by metal wiring such as Au, Ti, Al or the like. When a plurality of semiconductor light-emitting elements are formed on a common substrate, in order not to block light from the light-emitting layer, the metal wiring is not crossed over the upper surface of the p-type transparent electrode serving as a light extraction surface. The electrodes are connected.

  However, the light generated in the light emitting layer is emitted not only in the direction of the upper surface of the p-type transparent electrode but also in the direction of 360 ° in the vertical and horizontal directions. Some light is extracted in the direction. In the above prior art, these lights are absorbed and reflected by the metal wiring and cannot be taken out by being blocked, so that there is a problem that the light extraction efficiency is lowered. In Patent Document 1, because of the metal wiring connecting the electrodes, not only the light radiated to the side surface of the element is blocked, but also the area of the n-side electrode is formed large, and the metal wiring is formed on the entire surface of the n-side electrode. Since it is connected, the area where light is blocked is large and the light output is greatly reduced.

  In the above prior art, the light emitting device has been described. However, in the light receiving device in which the semiconductor light receiving elements are two-dimensionally formed, the metal wiring blocks light directed toward the depletion layer at the pn junction of each element, thereby detecting the light receiving device. There was a problem of lowering the sensitivity.

  The present invention was devised to solve the above-described problems, and is a semiconductor device in which a large number of GaN-based light-emitting elements or GaN-based light-receiving elements are two-dimensionally formed. An object of the present invention is to provide a GaN-based semiconductor device that is not obstructed by wiring.

  In order to achieve the above object, the invention according to claim 1 is a GaN-based semiconductor device in which a plurality of semiconductor elements to be GaN-based light-emitting elements or GaN-based light-receiving elements are two-dimensionally formed on a substrate, A positive electrode and a negative electrode of the semiconductor element are provided on the light receiving surface side or the light extraction surface side, a transparent electrode is formed as the positive electrode in a region in contact with the GaN-based semiconductor layer, and a part of the wiring connecting the electrodes Is a GaN-based semiconductor device characterized by being made of a transparent electrode material.

  The invention described in claim 2 is the GaN-based semiconductor device according to claim 1, wherein the transparent electrode material is made of ZnO or ITO.

  According to a third aspect of the present invention, in the invention according to any one of the first and second aspects, the part of the wiring connecting the electrodes is a wiring excluding a wire bonding electrode region. The GaN-based semiconductor device described.

  The invention according to claim 4 is the GaN-based semiconductor device according to any one of claims 2 and 3, wherein the positive electrode is composed of only the transparent electrode material. is there.

  The invention according to claim 5 is characterized in that the positive electrode is composed of the transparent electrode and a metal electrode provided on a part of the transparent electrode. The GaN-based semiconductor device according to any one of the above.

  According to a sixth aspect of the present invention, in the GaN-based semiconductor device according to the second or third aspect, the negative electrode is made of the same material as the transparent electrode. It is.

  The invention according to claim 7 is the GaN-based semiconductor device according to claim 2, wherein the negative electrode is a metal electrode.

  The invention of claim 8 is characterized in that the metal electrode is formed of any one of an Al film, a multilayer film of Al and Ni, and a multilayer film of Ti and Au. The GaN-based semiconductor device according to any one of the above.

  According to the present invention, a large number of semiconductor elements to be GaN-based light-emitting elements or GaN-based light-receiving elements are two-dimensionally formed on a substrate, and the positive electrode and the negative electrode of the semiconductor element are on the light-receiving surface side or light extraction surface. A transparent electrode is formed as a positive electrode in a region in contact with the GaN-based semiconductor layer and a wiring connecting the electrodes is formed of a transparent electrode material. Absorption and reflection are extremely reduced, and in the case of a light emitting device, the light extraction amount increases and the light output is improved, and in the case of a light receiving device, the light receiving sensitivity is improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a GaN-based semiconductor device comprising a single wafer according to the present invention.

  The GaN-based semiconductor device of the present invention has a configuration in which a number of GaN-based semiconductor elements are two-dimensionally formed on a common substrate, and FIG. 1 shows a structure in which GaN-based semiconductor elements are connected in parallel.

The GaN-based semiconductor is formed by a known MOCVD method or the like. Here, the GaN-based semiconductor is an AlGaInN quaternary mixed crystal, which is a so-called III-V group nitride semiconductor, and is a compound containing GaN. Al _x Ga _y In _z N (x + y + z = 1, 0 ≦ x ≦ 1) , 0 <y ≦ 1, 0 ≦ z ≦ 1). A GaN-based semiconductor element is mainly composed of a GaN-based semiconductor.

  A selective growth mask 11 is formed on the growth substrate 1, and an AlN buffer layer 2 is formed in a region where a portion of the selective growth mask 11 has been removed. On the AlN buffer layer 2, an undoped GaN layer 3, an n-type GaN layer 4, an active layer (light-emitting layer or light-receiving layer) 5, and a p-type GaN layer 6 are laminated in this order. Formed by law. Each GaN-based semiconductor element D is formed in a state of being separated by a method called selective lateral growth, and an isolation groove A for separating elements is formed just above the selective growth mask 11. Here, selective growth or selective lateral growth (ELO) is well known as a method of reducing dislocations.

The active layer 5 has a multiple quantum well structure including a barrier layer made of GaN and a well layer made of In _X1 Ga _{1 -X1} N (0 <X1). Further, a sapphire substrate or the like is used as the growth substrate 1, but any substrate having a hexagonal crystal structure (wurtzite structure) may be used. Further, an n-type impurity Si-doped GaN layer may be used instead of the undoped GaN layer 3.

  Here, in the forward bias, carrier recombination occurs in the active layer 5. At this time, if the forbidden band width is larger than the energy of the photon, light may be emitted along with recombination, and when this is applied, a light emitting element can be configured. On the contrary, when a photon having energy larger than the forbidden band is incident on the active layer 5, electrons are excited from the valence band to become conduction electrons, and there is a photovoltaic effect that is attracted to the built-in electric field and increases the drift current. When this is generated and applied, it can be configured as a light receiving element. Therefore, except for the composition ratio and the like, basically, the structure of FIG. 1 can be used as both a light emitting device and a light receiving device.

An insulating film is used as the selective growth mask 11 for selectively growing the AlN buffer layer 2 to the p-type GaN layer 6. Examples of the insulating film include SiO ₂ , Si ₃ N ₄ , and ZrO ₂ .

  Next, mesa etching is performed until a part of the n-type GaN layer 4 is exposed from the p-type GaN layer 6 to form a hexagonal mesa region D1. Therefore, the semiconductor element D is composed of a pedestal region D2 and a mesa region D1. An n-electrode (negative electrode) 7 is provided on the exposed n-type GaN layer 4, and a p-side transparent electrode (positive electrode) 8 is provided on the p-type GaN layer 6. The p-side transparent electrode 8 is made of ZnO (zinc oxide) or ITO (Indium Tin Oxide).

Except for a part of the upper surface of the p-side transparent electrode 8 and the upper surface of the n-electrode 7, the entire surface of each semiconductor element D is covered with an insulating film 9. The insulating film 9 is made of SiO ₂ , Si ₃ N ₄ , ZrO ₂ or the like that has high insulating properties and is transparent to the emission wavelength or incident light wavelength. The insulating film 9 is provided with a contact hole in a part on the n-electrode 7 and the p-side transparent electrode 8, and is connected to the wiring 12, the wiring 13, the wiring 14, and the wiring 15 through the contact hole. .

  The wirings 12 and 13 are made of a transparent electrode material, and are made of, for example, ZnO or ITO used for the p-side transparent electrode 8. The film thickness of the wirings 12 and 13 can be, for example, 2000 to 5000 mm. Thus, by forming the wiring with the same material as that of the transparent electrode, the light generated in the active layer 5 can be taken out without being blocked. The light generated in the active layer 5 is not only upward and downward, but also directed to the side surface and emitted from the device side surface. On the other hand, in the case where the configuration of FIG. 1 is a light receiving device, the light traveling toward the active layer 5 is not only from the top surface of the element, but is incident from the side surface of the element or is reflected inside the element and travels toward the active layer. Etc.

  When the wiring is made of metal as in the prior art, light is absorbed and reflected by the metal and the light is blocked, but in the present invention, the wiring is made of the same material as the p-side transparent electrode. Therefore, light can be transmitted and conductivity can be obtained. Therefore, if it is a light-emitting device, a light output will improve, and if it is a light-receiving device, the detection sensitivity of light will improve.

  The n electrode 7 is made of ZnO or ITO, which is the same material as the p-side transparent electrode 8. In this case, in the case of the light emitting device, the light generated in the active layer 5 is reflected inside the element and can be extracted to the outside toward the n-electrode 7 side. In the case of the light receiving device, light incident from the upper surface direction of the n-electrode 7 can be taken in and guided to the active layer 5 by reflection or the like inside the element.

  In particular, when the area of the n electrode 7 is large, the effect is great because light can be transmitted through the n electrode 7. When there is no need for light shielding at the n-electrode 7 because the area of the n-electrode 7 is small, the n-electrode 7 is made of a metal such as Al, or a metal multilayer in which Al / Ni is laminated in order from the lower layer. It may be formed of a film or a metal multilayer film laminated with Ti / Au. As described above, when the n-side electrode 7 is a metal electrode, the wiring 13 and the like are hardly peeled off.

  Next, FIG. 2 shows a structure in which elements are connected in parallel as in FIG. 1 and has almost the same configuration. However, a p-side metal electrode 81 is laminated on a part of the upper surface of the p-side transparent electrode 8, and this p The difference is that the p-side transparent electrode 8 and the wiring 12 are connected via the side metal electrode 81. The p-side metal electrode 81 in FIG. 2 is made of a metal such as Al, or a metal multilayer film laminated with Al / Ni or a metal multilayer film laminated with Ti / Au in order from the lower layer. In the case of FIG. 1, the positive electrode (p electrode) of the element is composed of only the p-side transparent electrode 8, but in the case of FIG. 2, the positive electrode (p electrode) of the element is the p-side transparent electrode 8. And the p-side metal electrode 81. In order to maximize light extraction or incidence, it is preferable to directly bond the p-side transparent electrode 8 and the wiring 12 as shown in FIG. 1. Since there is a possibility, the p-side transparent electrode 8 and the wiring 12 are joined via the p-side metal electrode 81 as shown in FIG.

  FIG. 7 is a plan view of the configuration of FIG. 1 or FIG. 2 as viewed from above, in order to make the relationship between the n electrode 7, the p-side transparent electrode 8 or the p-side metal electrode 81, and the metal wirings 12 and 13 easy to understand. In the figure, the insulating film 9 is shown through. Here, light emitted from the active layer 5 is extracted from the upper surface direction of the p-side transparent electrode 8. When functioning as a light receiving device, light is received by the active layer 5 from the upper surface direction of the p-side transparent electrode 8.

  For example, a part of the CC cross section in FIG. 7 corresponds to FIGS. 1 and 2, and the p-side transparent electrode 8 or the p-side metal electrode 81 and the n-electrode 7 of each GaN-based semiconductor element D have the same polarity. Is shown, and the GaN-based semiconductor elements D are connected in parallel. 8a is a region where the p-side metal electrode 81 is in contact with the wiring 12 or the wiring 14 when the p-side metal electrode 81 is formed, and the p-side transparent electrode when the p-side metal electrode 81 is not formed. 8 represents a p-side electrode junction region where the wiring 12 or the wiring 14 contacts, in other words, a contact hole.

  As shown in FIG. 7, except for the electrodes connected to the wirings 14 and 15 at the end, adjacent p electrodes or n electrodes of adjacent semiconductor elements are adjacent to each other with a separation groove A separating the elements. It is formed to do. The wirings 12, 13, 14, and 15 are connected to electrodes of many other semiconductor elements not shown. The wirings 14 and 15 are also made of the same material as the p-side transparent electrode 8, and may be made of, for example, ZnO or ITO as described above. The wirings 14 and 15 arranged outside the semiconductor element group may be non-transparent metal wirings.

  In the case of FIG. 7, for example, if the wiring 14 and the wiring 12 are connected to the same positive electrode, and the wiring 13 and the wiring 15 are connected to the same negative electrode, each of the 12 GaN-based semiconductor elements D in FIG. All are connected in parallel. At this time, each semiconductor element D does not operate unless power is supplied from the outside to the semiconductor device in which the plurality of semiconductor elements D are formed.

  Therefore, it is necessary to connect a wire for supplying power from the outside to the semiconductor device. In order to connect to this wire, a wire bonding metal is formed on one specific semiconductor element, and the wire bonding metal and the wire are connected. Usually, wire bonding requires a plus and minus electrode, and is provided in two places. For example, WB shown in FIG. 7 is assumed to be one place of a semiconductor element for wire bonding. Excessive force is easily applied to the wire, and the wiring around the WB is easily peeled off by ZnO or ITO material. Therefore, the wiring formed in the peripheral region of the WB is not made of the same material as the p-side transparent electrode 8 but is formed of a metal such as Al or Au.

  The peripheral region of WB is a metal wiring region indicated by a dotted line in the figure, and is a wiring that connects an electrode of the semiconductor element WB and an electrode of another semiconductor element adjacent thereto, and a separation groove A around the semiconductor element WB. The wiring provided along the line is a metal wiring. The same applies to FIG. 8 described later. In FIG. 7, as an example of the metal wiring region, a region extending over two adjacent elements D is shown. However, the present invention is not limited to this, and a region extending over three or more elements may be used. In addition, although the structure example in which the n-type layer is exposed is shown as the element D selected for the metal wiring region, it is not limited to this structure. For example, a p-type layer and a transparent conductive film are stacked, a mask for etching for exposing the n-type layer is formed, a stacked portion that is not mesa-etched is manufactured, and this stacked portion may be WB.

  On the other hand, unlike FIGS. 1 and 2, FIGS. 3 and 4 are different from FIGS. 1 and 2 in that p-electrodes (positive electrodes) and n-electrodes (negative electrodes) of each GaN-based semiconductor element D are connected to electrodes of different polarities. The structure which connected the element D in series is shown.

  As shown in FIGS. 3 and 4, the p-side transparent electrode 8 or the p-side metal electrode 81 of one element and the n-electrode 7 of the other element are formed so as to be adjacent to each other with a separation groove A separating the elements. ing. The same reference numerals as those in FIGS. 1 and 2 indicate the same structure, and the layer structure and material structure are the same except that the GaN-based semiconductor elements D are connected in series. FIG. 1 is shown in FIG. Corresponds to 4. Here, the wiring 20 is formed of a transparent electrode material like the wirings 12 and 13 and is made of, for example, ZnO or ITO used in the p-side transparent electrode 8.

  FIG. 8 is a plan view of the arrangement state including the configuration in which the respective GaN-based semiconductor elements D are connected in series as seen from above, and shows the state in which the insulating film 9 is seen. A part of the BB cross section in this figure corresponds to FIGS. Unlike FIG. 7, a group in which four GaN-based semiconductor elements D are connected in parallel has a configuration in which three columns are connected in series. Except for the electrodes connected to the wirings 21 and 22 at the end, for the elements connected in series, the p electrode of one element and the n electrode of the other element separate the elements between adjacent semiconductor elements. It is formed so as to be adjacent to each other with the separation groove A interposed therebetween. Further, the wirings 21 and 22 are made of the same material as that of the p-side transparent electrode 8, and are made of, for example, ZnO or ITO as described above. Similarly to the case of FIG. 7, the wirings 21 and 22 arranged outside the semiconductor element group may be non-transparent metal wirings. Although not shown, the wirings 20 to 22 are connected to the wire bonding electrodes and supplied with a voltage.

  7 and 8, the wiring for connecting the p-electrode and the p-electrode between adjacent semiconductor elements with the separation groove interposed therebetween, or the wiring for connecting the p-electrode and the n-electrode is a plan view. It is connected at the shortest distance without straddling the light extraction surface or the light receiving surface.

  Further, the wiring connecting the p-electrode and the p-electrode between adjacent semiconductor elements, or the wiring connecting the p-electrode and the n-electrode avoids all the 12 vertices formed in the hexagonal semiconductor element D. It has a configuration. Since both the hexagonal apex in the base region D2 of the GaN-based semiconductor element D and the hexagonal apex in the mesa region D1 form a corner, the electric field concentrates. Therefore, if the wiring between the electrodes is formed over any of the twelve vertices formed in the GaN-based semiconductor element D, the wiring and the GaN-based semiconductor element D are likely to be short-circuited. This is to avoid it.

  On the other hand, the shapes of the p electrode and the n electrode formed in each GaN-based semiconductor element D are shown in FIG. This is a plan view of the GaN-based semiconductor element D described in FIGS. The electrode is formed at a position where the light emitting area in the active layer 5 is maximized and the wiring between the semiconductor elements is simplified.

  As shown in FIGS. 5A to 5C, the positive electrode or the negative electrode is an electrode junction region having a shape using two sides sandwiching one side or apex of a hexagon similar to the element shape, The positive and negative electrode junction regions are arranged to face each other.

  In FIG. 5A, both the p-side electrode junction region 8a and the n-electrode 7 are formed in a quadrilateral having a long side parallel to one side of the hexagonal shape of the GaN-based semiconductor element D. In FIG. 5B, both the p-side electrode junction region 8a and the n-electrode 7 use two sides parallel to two sides of the hexagonal apex of the semiconductor element shape, and are formed in a “<” shape. Has been. In FIG. 5C, both the p-side electrode junction region 8a and the n-electrode 7 utilize two sides parallel to two sides of the hexagonal apex of the semiconductor element shape, and are formed in a fan shape. . In FIG.5 (c), it is good also as a triangle by making circular arc part into a linear shape instead of making it fan shape.

A method for manufacturing the GaN-based semiconductor device shown in FIGS. First, a selective growth mask 11 is formed on the growth substrate 1. For example, a sapphire substrate as a growth substrate 1 is put into an MOCVD (metal organic chemical vapor deposition) apparatus, and the temperature is raised to about 1050 ° C. while flowing hydrogen gas to thermally clean the sapphire substrate. Thereafter, SiO ₂ which is an insulating film is formed as a selective growth mask 11 on the sapphire substrate. Sputtering power is 300 W, sputtering atoms Ar are supplied at 20 cc / min, and sputtering is performed for 20 minutes in an atmosphere with a pressure of 1 Pa to form a SiO ₂ film with a thickness of about 1000 mm on the sapphire substrate.

Next, a resist is formed on the SiO ₂ film in a predetermined pattern by photolithography, and dry etching, for example, CF 4 gas is supplied in a plasma state at a pressure of 3 Pa and a power of 100 W to perform etching. The pattern of the selective growth mask 11 at this time is as shown in FIG. 6 as described later.

Thereafter, the AlN buffer layer 2 is grown. The AlN buffer layer 2 is a high-temperature AlN buffer layer, has a temperature of 900 ° C. or higher (eg, 900 ° C.), a growth pressure of 200 Torr, hydrogen as a carrier gas, and a flow rate of carrier hydrogen (H ₂ ) of 14 L. The flow rate of TMA (trimethylaluminum) was 20 cc / min, and the flow rate of NH ₃ (ammonia) was 500 cc / min. When the molar ratio of NH ₃ / TMA at this time is calculated, it is about 2600. Under this growth condition, a high-temperature AlN buffer layer 2 having a thickness of 30 mm is formed. Note that the insulating film used as the selective growth mask 11 includes Si ₃ N ₄ , ZrO _{2 and the} like in addition to the SiO ₂ .

  When the AlN buffer layer 2 is laminated in this way, not only can the AlN buffer layer 2 be thinly formed, but the AlN buffer layer 2 is not deposited on the selective growth mask 11 but is filled between the selective growth masks 11. Formed as follows.

  By the way, in order to form the separated semiconductor element D as shown in FIGS. 1 to 4, it is necessary to make the growth rate in the vertical direction larger than the growth rate in the horizontal direction. For this purpose, the opening of the selective growth mask 11 is formed by removing a part of the insulating film. The shape of the opening is shown in FIG.

  As shown in FIG. 6, a selective growth mask 11 having a large number of hexagonal openings 11a is used. In this way, a hexagonal element is obtained. The nitride semiconductor has a wurtzite type (hexagonal) crystal structure with a (0001) orientation, and has a crystal polarity (growth in the c-axis direction) in which Ga atoms or N atoms are in the growth surface direction.

  Therefore, a sapphire substrate or the like having the same wurtzite crystal structure is used as the growth substrate, and the main surface of the sapphire substrate has a C-plane, and a nitride semiconductor is stacked on the main surface. All C planes are in the growth surface direction. In this case, if the mask for selective growth having the hexagonal opening 11a shown in FIG. 6 is used, if the hexagonal side L1 is arranged parallel to the M-plane of the growth substrate, the crystal grown by selective growth is almost all. Since it grows in the vertical direction, it becomes a separated semiconductor layer.

Next, in the MOCVD apparatus, the growth temperature is set to 1020 ° C. to 1040 ° C., the supply of TMA out of NH ₃ and TMA is stopped, for example, trimethylgallium (TMGa) is supplied at 20 μmol / min, and the undoped GaN layer 3 Are stacked to a thickness of about 0.5 μm.

Thereafter, silane (SiH ₄ ) is supplied as an n-type dopant gas to grow the n-type GaN layer 4 with a thickness of about 4 μm. Next, the supply of TMGa and silane is stopped, the substrate temperature is lowered between 700 ° C. and 800 ° C. in a mixed atmosphere of ammonia and hydrogen, and triethylgallium (TEGa) is supplied at 20 μmol / min to obtain the active layer 5. The undoped GaN barrier layer is laminated, and trimethylindium (TMIn) is supplied at 200 μmol / min, and the InGaN well layer is laminated. A multiple quantum well structure is formed by repeating the GaN barrier layer and the InGaN well layer. The film thickness of the active layer 5 is formed to be about 0.1 μm, for example.

After the active layer 5 is grown, the growth temperature is increased to 1020 ° C. to 1040 ° C., and trimethylgallium (TMGa), which is a Ga atom source gas, ammonia (NH ₃ ), which is a nitrogen atom source gas, and p-type impurity Mg. CP ₂ Mg (biscyclopentadiethyl magnesium) as a dopant material is supplied, and a p-type impurity Mg-doped GaN layer 6 is grown to a thickness of about 0.3 μm.

  Next, mesa etching is performed until the n-type GaN layer 4 is exposed from the p-type GaN layer 6, and, for example, ZnO is formed on the p-type GaN layer 6 as a p-side transparent electrode 8 with a film thickness of about 2000 mm, and the p-side transparent When the p-side metal electrode 81 is formed on a part of the electrode 8, the p-side metal electrode 81 is formed, and the n-electrode 7 is formed on the exposed surface of the n-type GaN layer 4. When ZnO is used for the n-electrode 7, for example, the ZnO is formed to a thickness of about 2000 mm.

Thereafter, SiO ₂ is deposited as an insulating film 9 over the entire surface of the wafer by about 0.5 μm to ₂ μm. To coat the wafer surface with SiO _2, plasma CVD is used, power 300 W, and the growth temperature 400 ° C., silane (SiH ₄₎ 10cc / min, the _{N 2} O and 500 cc / min supply, SiO ₂ About 0.5 to 2 μm.

Next, SiO ₂ on the p-side transparent electrode 8 or the p-side metal electrode 81 and the n-electrode 7 is removed by wet etching or dry etching to form a contact hole. 1-4, 7 and 8, when ZnO is used for the wiring, ZnO is deposited in a thickness of 2000 to 5000 mm, and a part of the wiring is etched to form patterns of the wirings 12 to 15 and the wirings 20 to 22. Make it. Thus, the wiring and the p-side transparent electrode 8 or the p-side metal electrode 81, and the wiring and the n-electrode 7 are connected via the contact hole. In addition, the wirings 12 to 15 and the wirings 20 to 22 formed in the wire bonding region are formed of a metal such as Al or Au. The film thickness at this time is about 5000 mm.

  Further, when the wirings 12 to 15, the wirings 20 to 22, the p-side transparent electrode 8, the n-electrode 7 and the like are formed of ZnO, they are manufactured by a pulse laser deposition (PLD) method. In this case, sintered ZnO containing 2% to 3% Ga (gallium) is used as a laser irradiation target. By using Ga-doped ZnO, the p-side transparent electrode 8 and the p-type GaN layer can be brought into ohmic contact without annealing, and the conductivity of the wiring and the like is improved.

Note that the manufacturing of each semiconductor layer, along with hydrogen or nitrogen carrier gas, triethylgallium (TEGa), trimethyl gallium (TMG), ammonia _(NH 3), trimethyl aluminum (TMA), each of such trimethyl indium (TMIn) Reaction gas corresponding to the components of the semiconductor layer, silane (SiH ₄ ) as a dopant gas in the case of n-type, CP ₂ Mg (cyclopentadienylmagnesium) as a dopant gas in the case of p-type By supplying a gas and sequentially growing it in the range of about 700 ° C. to 1200 ° C., a semiconductor layer having a desired conductivity and a desired composition can be formed to a required thickness.

It is a figure which shows an example of the cross-sectional structure of the GaN-type semiconductor device of this invention. It is a figure which shows an example of the cross-sectional structure of the GaN-type semiconductor device of this invention. It is a figure which shows an example of the cross-sectional structure of the GaN-type semiconductor device of this invention. It is a figure which shows an example of the cross-sectional structure of the GaN-type semiconductor device of this invention. It is a figure which shows the example of a shape of the positive electrode of a semiconductor element in a GaN-type semiconductor device of this invention, and a negative electrode. It is a figure which shows the example of a shape of the mask for selective growth. It is a top view which shows the wiring state at the time of connecting a semiconductor element in parallel. It is a top view which shows the wiring state at the time of connecting a part of semiconductor element in series.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Growth substrate 2 AlN buffer layer 3 Undoped GaN layer 4 n-type GaN layer 5 Active layer 6 p-type GaN layer 7 n-electrode 8 p-side transparent electrode 81 p-side metal electrode 9 insulating film 11 selective growth mask 12 wiring 13 wiring 20 Wiring

Claims (8)

A GaN-based semiconductor device in which a plurality of semiconductor elements to be GaN-based light-emitting elements or GaN-based light receiving elements are two-dimensionally formed on a substrate,
The positive electrode and the negative electrode of the semiconductor element are provided on the light receiving surface side or the light extraction surface side, a transparent electrode is formed as the positive electrode in a region in contact with the GaN-based semiconductor layer, and one of the wirings connecting the electrodes A GaN-based semiconductor device characterized in that the portion is formed of a transparent electrode material.   2. The GaN-based semiconductor device according to claim 1, wherein the transparent electrode material is made of ZnO or ITO.   3. The GaN-based semiconductor device according to claim 1, wherein a part of the wiring connecting the electrodes is a wiring excluding a wire bonding electrode region. 4.   4. The GaN-based semiconductor device according to claim 2, wherein the positive electrode is composed only of the transparent electrode material. 5.   4. The GaN system according to claim 2, wherein the positive electrode includes the transparent electrode and a metal electrode provided on a part of the transparent electrode. 5. Semiconductor device.   4. The GaN-based semiconductor device according to claim 2, wherein the negative electrode is made of the same material as that of the transparent electrode. 5.   The GaN-based semiconductor device according to claim 2, wherein the negative electrode is a metal electrode. 8. The GaN according to claim 5, wherein the metal electrode is formed of any one of an Al film, a multilayer film of Al and Ni, and a multilayer film of Ti and Au. Semiconductor device.

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