JP4273928B2 - III-V nitride semiconductor device - Google Patents

Description

  The present invention relates to a III-V nitride semiconductor device. In particular, the present invention provides a structure of a III-V group nitride semiconductor device having a high electrostatic withstand voltage.

  In recent years, III-V nitride semiconductors have a wide band gap, have stable crystals, and do not use environmental pollutants such as arsenic. Electronic devices such as elements, light receiving elements, solar cells, and transistors have been actively studied. However, since the group III-V nitride semiconductor is extremely difficult to grow crystals compared to other compound semiconductors and it is difficult to obtain high-quality crystals, the electrostatic breakdown voltage of a semiconductor device using the semiconductor is still low. It is. That is, when a high voltage is applied to the semiconductor element, there are problems that the element is destroyed and various characteristics such as light emission characteristics are deteriorated. For this reason, attention is required in the process of manufacturing a semiconductor element and in assembling a product using the element.

  Although group III-V nitride semiconductor light-emitting devices are being widely used as light-emitting devices in the green, blue to ultraviolet regions, there is still room for improvement in characteristics other than the light emission intensity. In particular, the electrostatic withstand voltage is much lower than that of gallium / arsenic light emitting elements and indium / phosphorous light emitting elements, and a significant improvement in electrostatic withstand voltage is expected. Here, in order to improve the electrostatic withstand voltage of the group III-V nitride semiconductor light emitting device, the following proposals have been made.

JP-A-10-135519

  In the technique disclosed in the above publication, a capacitor is inserted in parallel with a pn junction constituting a light emitting element on an equivalent circuit. This technology attempts to prevent metal migration and defect growth by preventing a sharp increase in current by slowing the surge rise by shorting the high-frequency component of the surge voltage with this capacitor. Is. In order to improve the electrostatic withstand voltage effect, it is necessary to reduce the frequency of the electrostatic voltage that is short-circuited by the capacitor as much as possible. Therefore, it is necessary to increase the capacitance of the capacitor. However, the size of the capacitor that can be formed on one chip is naturally limited, and cannot be short-circuited to a low frequency, and the effect of preventing electrostatic withstand voltage has not been obtained so much.

  Accordingly, an object of the present invention is to further improve the electrostatic withstand voltage of a III-V nitride semiconductor device.

The invention according to claim 1 for solving the above-described problem is that a group III-V nitride semiconductor is used as a material of each layer, and at least a first electrode and a first conductivity type to which the first electrode is connected In a semiconductor element having a first layer, a second electrode, and a second conductive type second layer to which the second electrode is connected, zinc oxide or oxide that connects the first electrode and the second electrode A III-V nitride semiconductor comprising a protective film made of a material containing zinc and having a non-linear resistance characteristic for absorbing energy by rapidly decreasing the resistivity with respect to a voltage equal to or higher than a threshold voltage It is an element.

  Here, if the first conductivity type is an n conductivity type, the second conductivity type is a p conductivity type. Of course, if the first conductivity type is a p conductivity type, the second conductivity type is an n conductivity type. The semiconductor element according to the present invention is applied to a semiconductor element having at least these two types of conductive layers and electrodes connected to the respective layers. Therefore, it is not necessary that the first layer and the second layer are directly joined. The first layer and the second layer may be directly joined, or between the layers, a layer of the first conductivity type or the second conductivity type, or a layer to which no dopant is intentionally added (intrinsic semiconductor or A layer made of a semiconductor having the first conductivity type or the second conductivity type, which is less diffused, or a plurality of these layers may be interposed. In the case of a light-emitting element or light-receiving element having a double hetero structure, generally, a light-emitting layer that converts electrical energy into light energy between the first layer and the second layer, or light energy that is converted into electrical energy. There is a light receiving layer, and the light emitting layer and the light receiving layer generally have SQW and MQW structures. In addition, a large number of functional layers such as a guide layer and a clad layer are generally present. Since the first layer and the second layer are generally considered as contact layers for improving the ohmic property with respect to the first electrode and the second electrode, the first layer and the second layer are between the first layer and the light emitting layer or the light receiving layer. Alternatively, a plurality of functional layers such as another contact layer, a strain relaxation layer, a cladding layer, and a guide layer may be formed between the second layer and the light emitting layer or the light receiving layer as necessary. In addition, each of these functional layers may form a multilayer or a multiple quantum well structure. The structure of each layer differs depending on the type of semiconductor element, but the point is that a semiconductor element having positive and negative electrodes and at least two layers to which these electrodes are connected is used. The invention is applicable.

  When a driving voltage is applied between the first electrode and the second electrode, the semiconductor element emits light, receives light, changes its resistance, receives light, induces a voltage, and performs an amplification action such as a transition. However, static electricity, surge voltage during switching, and the like are also applied between these two electrodes. In the present invention, a protective film having a nonlinear resistance characteristic is formed between the electrodes. The protective film absorbs energy such as static electricity and surge applied between the two electrodes. The protective film may be a single layer or a plurality of layers made of different materials. Further, it may be a multilayer of a protective film having a non-linear resistance characteristic and an insulating film such as silicon dioxide, titanium oxide, silicon nitride, or alumina that does not have this characteristic. It may be a mixture or composition in which the material is mixed. The insulating film may be located below or above the protective film. Further, a metal film or a metal film may be present between the protective film and the insulating film in the protective film. The predetermined voltage (threshold voltage) at which the protective film causes a sudden current flow is controlled by the distance between the first electrode and the second electrode, that is, the path length of the current in the protective film, the composition of the material, the composition ratio, etc. can do. The energy absorption capability can be controlled by the cross-sectional area of the current path in the protective film, the material components, the composition ratio, and the like. In short, these values can be controlled by the dimensions of the protective film, the positional relationship between the first electrode and the second electrode, and therefore the shape (cross section, length) of the current path, the composition of the material, the composition ratio, etc. Is possible.

Moreover, coercive Mamorumaku is that is composed of a material containing zinc oxide or zinc oxide.
This zinc oxide has a remarkable non-linear characteristic in the voltage-current characteristic. That is, when the voltage applied between two electrodes sandwiching a protective film made of zinc oxide or a material containing zinc oxide is smaller than a predetermined voltage, the resistivity is very large, and the protective film functions as an insulator. To do. However, when the voltage applied between the two electrodes becomes equal to or higher than the predetermined voltage, the resistivity of the protective film decreases rapidly, a current flows rapidly between the electrodes, and the voltage between the electrodes does not increase.

According to a second aspect of the present invention, in the first aspect of the invention, the first electrode is formed in the exposed region of the first layer, and the protective film is formed of the second electrode formed on the second layer and the second electrode. It is formed along the side wall of each layer so as to connect one electrode.
The present invention and the invention of claim 1 include an element having two electrodes on the same surface side of a semiconductor element and an element having respective electrodes on both sides of the semiconductor element. When two electrodes are formed on the same side of the semiconductor element, the first electrode is formed on the exposed first layer by removing each layer above a part of the first layer. . When electrodes are formed on both sides of the semiconductor element, the first electrode is formed on the back surface of the semiconductor element, and the second electrode is formed on the surface of the semiconductor element or vice versa. In short, the feature of the invention of claim 2 is that the protective film is formed along the side wall of each layer constituting the semiconductor element so as to connect the first electrode and the second electrode. With this configuration, overcurrent (for example, surge) due to overvoltage is absorbed by the protective film.
Furthermore, in the invention described in claim 3, since a metal layer in which an induced current is consumed as an eddy current loss when a current flows through the protective film is formed in the protective film, the energy absorption capability is improved.

According to a fourth aspect of the present invention, in the first aspect of the invention, the first electrode is formed on the exposed region of the first layer, the protective film is formed on at least the first electrode, and the second electrode is the second electrode. It is formed on the layer and extended to a position facing the first electrode through the protective film.
The two electrodes may be formed on the same surface side of the semiconductor element, or may be formed on both surfaces of the semiconductor element, as in the invention of claim 2 . In the present invention, it is sufficient that the protective film is formed on at least the first electrode and the second electrode formed so as to extend on the protective film is present. Thereby, it can be set as the structure where a protective film exists between two electrodes. The protective film should just be formed at least on the whole surface or a part except the part electrically connected to the exterior of the 1st electrode, and may be formed to the 2nd layer along the side wall of each layer. When the protective film is formed up to the second layer along the side wall of each layer, the second electrode is formed on the protective film so as to extend to the position of the first electrode. When the protective film is not formed on the side wall of each layer, an insulating film is usually formed to insulate between the second electrode and the side wall of each layer. When the protective film is formed on the side wall of each layer, the layer formed on the side wall may be a multilayer with an insulating film or a metal layer in addition to the protective film. Is the same. Further, it is sufficient that a protective film exists at least between the first electrode and the second electrode extended on the first electrode, and a multilayer of the protective film and the insulating film and a metal film are present inside. A metal film may be present between the protective film and the insulating film and the protective film. In short, it is configured to increase the amount of overcurrent (surge) absorption due to overvoltage.

According to a fifth aspect of the present invention, in the first aspect of the invention, the second electrode is formed on a plane of the second layer, the protective film is formed at least on a part of the second electrode, and the first electrode is It is formed on the first layer and is extended to a position facing the second electrode through a protective film.
In contrast to the invention of claim 4, the present invention comprises a protective film and an extended first electrode on the second electrode. Therefore, the matters described in the invention of claim 4 can be applied to the invention of claim 5. The second electrode may be formed on the entire surface or part of the second layer. For example, when light is output to the outside from the second layer side or light is incident from the outside, the second electrode is generally a transparent electrode and faces both sides of the flitch chip type or semiconductor element. In the case of forming two electrodes, a thick metal electrode is obtained. The second electrode can be interpreted as including a pad electrode formed on the transparent electrode.

According to a sixth aspect of the present invention, in the fourth aspect of the present invention, the protective film is also formed on the side wall of each layer, and the second electrode extends on the protective film to a position facing the first electrode. It is characterized by being formed.
As described above, the protective film may be a single layer or a multilayer, and may be used together with other insulating films or metal films.

According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the protective film is also formed on the sidewall of each layer, and the first electrode extends on the protective film to a position facing the second electrode. It is characterized by being formed.
This is the same as the invention of claim 6.

The invention according to claim 8 is the invention according to any one of claims 2 to 7, wherein the exposed portion of the first layer is formed by removing each layer on a part of the plane of the first layer. It is a part formed by the above.
The present invention limits the configuration in which the first electrode and the second electrode are formed on the same surface of the semiconductor layer.

The invention according to claim 9 is the invention according to any one of claims 1 to 7, wherein the first electrode and the second electrode are opposed to each other so as to sandwich each layer on different surfaces of the semiconductor element. It is characterized by being formed.
This invention limits the structure which formed the 1st electrode and the 2nd electrode, respectively on both surfaces (back surface and front surface) of the semiconductor layer. When the semiconductor element uses a conductive substrate, this configuration can also be adopted.

In the present invention, a protective film having a non-linear resistance characteristic that connects the first electrode and the second electrode is formed. The non-linear resistance characteristic is a characteristic in which the resistivity is very large when the applied voltage is smaller than the predetermined voltage, and the resistivity is rapidly decreased when the applied voltage is equal to or higher than the predetermined voltage. By adopting this configuration, when a normal driving voltage for driving the semiconductor element is applied between the first electrode and the second electrode, the protective film functions as an insulator, The semiconductor element can be operated without being bypassed. When a voltage that is considerably higher than the normal drive voltage and is equal to or higher than a predetermined voltage (threshold voltage) is applied between the first electrode and the second electrode, the resistivity of the protective film rapidly decreases, and the protection Current is passed through the membrane, current is bypassed, and no large current flows through each layer. As a result, the voltage between the first electrode and the second electrode does not increase, and a large breakdown current does not flow in each layer. Therefore, the semiconductor element is not destroyed and the characteristics are not deteriorated. Since this protective film has a non-linear resistance characteristic, it can be used reversibly many times if it does not break down. The semiconductor element manufacturing process, the product assembly process using this element, the product It is resistant to static electricity and surge applied during use. As a result, the production yield of the product is improved and the product quality is improved.

Furthermore, the protective film is made of zinc oxide or a material containing zinc oxide, whereby a semiconductor element with improved electrostatic withstand voltage can be effectively obtained.
The inventions of claims 2 , 4, 5, and 6 are configured in the arrangement relationship between the protective film, the first electrode, and the second electrode. With these configurations, the protective film can control the predetermined voltage and energy absorption capacity that the current bypasses.

  The best mode for carrying out the present invention will be described. The present invention can be used as a semiconductor element for an electronic device such as a light emitting element (light emitting diode, laser diode, etc.), a light receiving element, a solar cell, and a transistor.

In the case of a light emitting element, the following configuration can be adopted. The multiple quantum well structure constituting the light emitting layer is a well composed of a group III nitride compound semiconductor Al _y Ga _1-yz In _z N (0 ≦ y <1, 0 <z ≦ 1) containing at least indium (In) Those containing layers are desirable. The structure of the light emitting layer includes, for example, a well layer made of doped or undoped Ga _1-z In _z N (0 <z ≦ 1), and a group III nitride having an arbitrary composition having a larger band gap than the well layer. Examples thereof include a barrier layer made of a physical compound semiconductor AlGaInN. A preferable example is an undoped Ga _1-z In _z N (0 <z ≦ 1) well layer and a barrier layer made of undoped GaN. Here, doping means that a dopant is intentionally included in the source gas and added to the target layer, and undoping does not intentionally add a dopant without including the dopant in the source gas. I mean. Therefore, undoped includes a case where it is naturally doped by diffusing from the adjacent layer.

  Any manufacturing method can be used as a method for manufacturing a group III-V nitride semiconductor device according to the present invention. Specifically, sapphire, spinel, Si, SiC, ZnO, MgO, or a group III-V nitride compound single crystal or the like can be used as a substrate for crystal growth. The methods for crystal growth of III-V nitride compound semiconductor layers include molecular beam vapor phase epitaxy (MBE), metalorganic vapor phase epitaxy (MOVPE), hydride vapor phase epitaxy (HDVPE), and liquid phase epitaxy. Laws are effective.

Table III-V nitride semiconductor layers, at least _{Al x Ga y In 1-xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) of the semiconductor element It can be formed of a III-V nitride compound semiconductor composed of a binary, ternary or quaternary semiconductor. Some of these group III elements may be replaced by boron (B) and thallium (Tl), and part of nitrogen (N) may be phosphorus (P), arsenic (As), antimony (Sb ) Or bismuth (Bi).

  Further, when an n-type layer is formed using these semiconductors, Si, Ge, Se, Te, C, or the like is added as an n-type impurity, and when a p-type layer is formed, p is used. As the type impurity, Zn, Mg, Be, Ca, Sr, Ba or the like can be added.

As shown in FIG. 9, when the applied voltage is smaller than a predetermined value (threshold voltage) Vt, the non-linear resistance characteristic of the protective film used in the present invention is high in resistivity and no current flows. When the voltage becomes equal to or higher than a predetermined value Vt, the resistivity decreases rapidly, and the current flows rapidly. As a material exhibiting such characteristics, there is zinc oxide. Alternatively, a material containing zinc oxide can be used. For example, a rare earth element oxide (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc.) mainly composed of zinc oxide. Material), alkaline earth element oxides (Mg, Ca, Ba, Sr, etc.), trivalent elements (B, Al, Ga, In, Y, Cr, etc.) A material containing one or a plurality of oxides of Fe, Sb, Mo, W, etc. can be used. Further, a material containing cobalt oxide and a material containing silver can be used for the composition. When there are many Sr oxides, a nonlinear coefficient can be enlarged, and when silver is included, energy absorption can be enlarged. The oxides of the trivalent elements exist at the grain boundaries and have a function of improving the insulation, and a function of existing at the grain boundaries and reducing the resistance. The threshold voltage (predetermined voltage) can be controlled. Also, when forming a protective film, as a main component of these materials, silicon oxide such as SiO _2, aluminum oxide, silicon nitride, such as SiN, such as Al ₂ O _3, aluminum nitride such as AlN, oxides such as TiO ₂ A mixture or composition with an insulating material such as titanium nitride such as titanium or TiN may be used. By controlling the blending ratio and composition ratio, the threshold voltage Vt and the energy absorption amount can be controlled.

  As a method for forming the protective film, it is possible to use a vapor deposition method such as sputtering using these single or plural compositions as targets.

  In all the drawings, the layer thickness is not displayed in proportion to the actual thickness of each layer, and the aspect ratio is not real. In short, the layer structure is expressed so as to be easily understood.

FIG. 1 is a schematic cross-sectional view of a semiconductor light emitting device 100 according to an embodiment of the present invention. In the semiconductor light emitting device 100, as shown in FIG. 1, a buffer layer 102 made of aluminum nitride (AlN) and having a thickness of about 15 nm is formed on a sapphire substrate 101 having a thickness of about 300 μm. A layer 103 made of GaN having a thickness of about 500 nm is formed, and an n-type contact layer 104 having a thickness of about 5 μm made of GaN doped with silicon (Si) at 1 × 10 ¹⁸ / cm ³ (high carrier concentration n). ⁺ Layer: equivalent to the first layer). On the n-type contact layer 104, an n-type semiconductor layer 105 made of Si-doped Al _0.1 Ga _0.9 N having a thickness of about 100 nm is formed.

On the n-type semiconductor layer 105, three pairs of a well layer 1061 made of non-doped In _0.2 Ga _0.8 N with a thickness of 3 nm and a barrier layer 1062 made of non-doped GaN with a thickness of 20 nm are stacked to form a multiple quantum well structure. The light emitting layer 106 is formed.

Further, a p-type layer 107 made of 25 nm-thick p-type Al _0.15 Ga _0.85 N doped with Mg 2 × 10 ¹⁹ / cm ³ is formed on the light-emitting layer 106. A p-type contact layer 108 (corresponding to the second layer) made of 100-nm-thick p-type GaN doped with 8 × 10 ¹⁹ Mg is formed on 107.

  Further, a light-transmitting thin film p-electrode 110 (corresponding to the second electrode) is formed on the p-type contact layer 108, and an n-electrode 140 (corresponding to the first electrode) is formed on the n-type contact layer 104. Has been. The translucent thin film p-electrode 110 includes a first layer 111 made of cobalt (Co) having a thickness of about 1.5 nm directly bonded to the p-type contact layer 108 and a gold (Au) having a thickness of about 6 nm bonded to the cobalt film. ) And the second layer 112.

  The thick p-electrode 120 (also corresponding to the second electrode) includes a first layer 121 made of vanadium (V) with a thickness of about 18 nm, a second layer 122 made of gold (Au) with a thickness of about 1.5 μm, A third layer 123 made of aluminum (Al) having a thickness of about 10 nm is sequentially laminated on the translucent thin film p-electrode 110.

  An n-electrode 140 having a multilayer structure is formed of a first layer 141 made of vanadium (V) having a thickness of about 18 nm and aluminum (Al) having a thickness of about 100 nm on a part of the n-type contact layer 104 which is partially exposed. It is comprised by laminating | stacking the 2nd layer 142 which consists.

  In addition, the n electrode 140 and the translucent thin film p electrode 110 are connected, and a protective film 130 made of a ZnO film is formed on the sidewalls of the n-type contact layer 104, the light emitting layer 106, the p-type layer 107, and the p-type contact layer 108. Is formed by sputtering. The protective film 130 is connected to the end of the translucent thin film p-electrode 110 and the end of the n-electrode 140, and is formed to a thickness of 5 to 10 μm.

  A reflective metal layer 150 made of aluminum (Al) having a thickness of about 500 nm is formed by metal vapor deposition on the outermost lowermost portion corresponding to the bottom surface of the sapphire substrate 101. The reflective metal layer 150 may be a metal such as Rh, Ti, or W, or a nitride such as TiN or HfN.

Since a protective film made of zinc oxide is formed between the n-electrode 140 and the translucent thin film p-electrode 110 as described above, when an overvoltage is applied between both electrodes, If the overvoltage is equal to or higher than a predetermined voltage, the current bypasses from the translucent thin film p-electrode 110 to the n-electrode 140, the voltage between the electrodes does not rise above the predetermined voltage, and the overcurrent is generated inside the light emitting layer 106 and the like. It does not flow into the layer. As a result, the destruction of the element is prevented and the crystal defects existing in each layer are not increased, so that the deterioration of the element characteristics is prevented. The protective film 130 may be formed on the entire periphery of the side wall of each layer, and is formed by etching and removing each layer above the electrode forming portion of the n-type contact layer 104 as shown in FIG. The n-type contact layer 104 may be formed only around the exposed portion. Further, the protective film 130 may be a film that also functions to protect the semiconductor light emitting element 100 such as contamination, and is further oxidized on substantially the entire surface of the protective film 130 and the translucent thin film p-electrode 110. An insulating film made of silicon (SiO ₂ ) or the like may be formed as a normal protective film. Further, since the thickness of the protective film 130 is determined by the material composition, shape, threshold voltage to be set, and the like, it can be normally used in the range of 0.1 to 10 μm. However, the thickness is not particularly limited.

2A and 2B are a plan view illustrating the basic structure 10 of the light emitting element and a cross-sectional view as viewed from the A direction when the basic structure 10 is cut along a center line. Parts corresponding to those in FIG. 1 are denoted by the same reference numerals.
In FIG. 2A, a translucent thin film p-electrode 110 (corresponding to the second electrode) is formed on the top of the basic structure 10. However, the metal layer located at the top may be formed thick so that it can be replaced with a reflective metal layer or the like, and the element may be a flip lip type. In consideration of ohmic properties, adhesion, translucency (or reflectivity), electrical resistance, corrosion resistance, and the like, the metal layers may be formed from a plurality of metal layers.

  The material for forming the crystal growth substrate 101 can be arbitrarily selected from sapphire, gallium nitride (GaN), silicon carbide (SiC), and other known crystal growth substrate materials. An n-type contact layer 104 (corresponding to the first layer), a light-emitting layer 106, and a p-type contact layer 108 (in the second layer) are formed on the buffer layer 102 that is directly grown on the crystal growth surface of the crystal growth substrate 101. Are sequentially stacked by crystal growth. The crystal growth method for laminating these semiconductor layers may be arbitrary. The translucent thin film p-type electrode 110 is formed by, for example, vapor deposition after the p-type contact layer 108 is laminated.

The exposed hole bottom surface 104 a of the n-type contact layer 104 and the side wall surface C of each semiconductor layer are surfaces exposed by etching from the top to the middle of the n-type contact layer 104.
Each semiconductor layer may be formed from a plurality of semiconductor layers, and the composition and the like of each semiconductor layer may be known or arbitrary. The layer structure is shown in a simplified manner and may have a number of functional layers as in the structure of FIG.
Hereinafter, in this specification, an embodiment in which the protective film 131 is provided over substantially the entire surface of the side wall C of the basic structure 10 of such a light emitting diode will be exemplified.

FIG. 3 is a cross-sectional view of the light emitting diode 200 of the second embodiment. The light emitting diode 200 includes the basic structure 10 (FIG. 2), and the cross section shown in FIG. 3 represents a cross section at the same position as the cross section viewed in the direction A in FIG. is there.
The translucent thin film p-electrode 110 (corresponding to the second electrode) is not shown in more detail, but is a first layer made of cobalt (Co) having a thickness of about 1.5 nm that is directly bonded to the p-type contact layer 108. And a second layer made of gold (Au) having a film thickness of about 6 nm bonded to the cobalt film (first layer).
A thick film p-electrode 120 (pad electrode) is formed on the translucent thin film p-electrode 110. Although not shown in more detail, the thick p-electrode 120 includes a first layer made of vanadium (V) with a thickness of about 18 nm, a second layer made of gold (Au) with a thickness of about 1.5 μm, A third layer made of aluminum (Al) having a thickness of about 10 nm is sequentially laminated on the translucent thin film p-electrode 110.

  An n-electrode 140 (corresponding to the first electrode) having a multilayer structure is formed on the exposed hole bottom surface 104a of the n-type contact layer 104 by vapor deposition with a first layer 141 made of vanadium (V) having a film thickness of about 18 nm. The second layer 142 made of aluminum (Al) having a thickness of about 100 nm is sequentially laminated. The reason why vanadium is used for the first layer 141 is to ensure good ohmic properties.

  The first protective film 131 has an arbitrary composition among the above-described compositions mainly composed of zinc oxide or zinc oxide. The first protective film 131 is formed by sputtering or vapor deposition. When the exposed hole bottom surface 104a of the n-type contact layer 104 is formed, the first protective film 131 is formed over substantially the entire side wall surface C of the exposed semiconductor layer. Yes. That is, the first protective film 131 is formed on any of the three side surfaces C surrounding the n-electrode 140. Furthermore, the skirt of the first protective film 131 extends to the translucent thin film p-electrode 110 and the n-electrode 140, and the first protective film 131 is electrically connected to these electrodes.

  Further, a metal layer 160 made of copper (Cu) and a second protective film 132 made of zinc oxide are sequentially laminated on the first protective film 131, and as a result, the metal layer 160 is The structure is arranged in a protective film. Similarly to the first protective film 131, the second protective film 132 is also electrically connected to the n electrode 140 and the translucent thin film p electrode 110. The total thickness of the first protective film 131 and the second protective film 132 together is 1 μm.

In this configuration, when a surge current flows through the first protective film 131 and the second protective film 132, an induced current flows through the internal metal layer 160, and this current is consumed as eddy current loss. For this reason, energy absorption capability improves. Also in the present embodiment, as in the first embodiment, the first protective film 131 and the second protective film 132 may be films that also have a protective function such as contamination with respect to the light emitting diode 200. Further, an insulating film made of silicon oxide (SiO ₂ ) or the like may be formed as a normal protective film on substantially the entire surface of the protective film 132 or the translucent thin film p-electrode 110. In the present embodiment, as shown in FIG. 2, the first protective film 131 and the second protective film 132 surround the n-type contact layer 104 in a region surrounding the exposed n-type contact layer 104 from three directions. Is formed. This is based on the discovery of the inventors that electrostatic breakdown occurs in each of the surrounding layers close to the n-electrode 140. In other words, this configuration is intended to effectively prevent electrostatic breakdown of the element by forming the protective films 131 and 132 in the portion where electrostatic breakdown occurs.

FIG. 4 is a cross-sectional view of the semiconductor light emitting device 300 of the third embodiment. In this embodiment, an extension portion 143 (corresponding to a first electrode) made of aluminum (Al) is formed on the protective film 130 in the first embodiment shown in FIG. The thickness of the protective film 130 on the translucent thin film p-electrode 110 is 5 μm. According to this configuration, the protective film 130 exists between the translucent thin film p-electrode 110 and the n-electrode extension 143 above the p-type contact layer 108, thereby increasing the current cross-sectional area. And the amount of energy absorption can be increased. As a result, the electrostatic withstand voltage is improved. In this configuration, a laminated structure of a protective film, a metal layer, and a protective film may be employed as in the second embodiment. Also in the present embodiment, as in the first embodiment, the protective film 130 may be a film that also functions as a protective function against contamination of the semiconductor light emitting element 300, or the entire upper surface of the n-electrode extension 143 or the transparent surface. An insulating film made of silicon oxide (SiO ₂ ) or the like may be formed as a normal protective film over substantially the entire surface of the light thin film p-electrode 110.

FIG. 5 is a cross-sectional view showing a semiconductor light emitting device 400 of Example 4, and FIG. 6 is a plan view thereof. This embodiment is a flip-chip type light emitting element. Corresponding layers in the previous embodiment are given the same numbers. A buffer layer 102 made of aluminum nitride (AlN) and having a thickness of about 200 mm is provided on the sapphire substrate 101, and a high carrier concentration n ⁺ layer made of silicon (Si) -doped GaN and having a thickness of about 4.0 μm. An n-type contact layer 104 (corresponding to the first layer) is formed. A light emitting layer 106 having a multiple quantum well structure (MQW) made of GaN and Ga _0.8 In _0.2 N is formed on the layer 104. A p-type layer 107 made of magnesium (Mg) -doped Al _0.15 Ga _0.85 N and having a thickness of about 600 mm is formed on the light emitting layer 106. Further, on the p-type layer 107, a p-type contact layer 108 (corresponding to the second layer) made of magnesium (Mg) -doped GaN and having a thickness of about 1500 mm is formed.

  A p-electrode 150 (corresponding to the second electrode) is formed on the p-type contact layer 108 as a multi-thick film electrode by metal deposition, and an n-electrode 140 (corresponding to the first electrode) is formed on the n-type contact layer 104. Equivalent) is formed. The p-electrode 150 includes a first metal layer 151 bonded to the p-type contact layer 108, a second metal layer 152 formed on the first metal layer 151, and a third metal formed on the second metal layer 152. The metal layer 153 has a three-layer structure.

  The first metal layer 151 is a metal layer made of rhodium (Rh) or platinum (Pt) having a thickness of about 0.3 μm and bonded to the p-type contact layer 108. The second metal layer 152 is a metal layer made of gold (Au) having a thickness of about 1.2 μm. The third metal layer 153 is a metal layer made of titanium (Ti) having a thickness of about 30 mm.

  The n-electrode 140 having a two-layer structure includes a vanadium (V) layer 141 having a thickness of about 175 mm and an aluminum (Al) layer 142 having a thickness of about 1.8 μm on a part of the n-type contact layer 104 that is partially exposed. Are sequentially laminated.

  A protective film 133 made of a composition containing zinc oxide as a main component is formed to a thickness of 3 μm on a significant portion of the upper surface of the p-electrode 150 thus formed. An extension portion 143 made of aluminum is formed on the protective film 133, and the extension portion 143 is opposed to the p electrode 150 via the protective film 133 on the upper surface of the p electrode 150. Yes. The exposed portion of the p electrode 150 and the exposed portion of the n electrode 140 are connected to the bump. As described above, in the flip chip type light emitting element, since the protective film 133 having a relatively large area can be formed on the p-electrode 150, the amount of energy absorption can be increased and the electrostatic withstand voltage can be improved. . In addition, the energization start voltage (threshold voltage) of the protective film 133 can be controlled by changing the thickness of the protective film 133 or adjusting the components of the protective film 133.

In the present embodiment, the protective film 133 may be configured to connect the p-electrode 150 and the n-electrode 140 without providing the extension portion 143 as in the first embodiment of FIG. The protective film may be formed as a plurality of layers as in the second embodiment of FIG. 3, and a metal layer may be interposed therebetween. That is, in the example of FIG. 5, the metal layer may be formed in the protective film 133. . Further, as in the first embodiment, the protective film 133 may be a film having a protective function such as contamination for the semiconductor light emitting device 400, or the entire upper surface of the n-electrode extension 143 or the p-electrode 150. In addition, an insulating film made of silicon oxide (SiO ₂ ) or the like may be formed as a normal protective film up to substantially the whole.

FIG. 7 is a cross-sectional view of the light emitting diode 500 of the fifth embodiment. This embodiment is the same as the first embodiment shown in FIG. 1, except that the extension 115 of the translucent thin film p-electrode is electrically connected to the translucent thin-film p-electrode 110 made of aluminum (Al) on the protective film 130. (Corresponding to the second electrode) is formed. However, the protective film 130 protrudes over the n-electrode 140 in a considerable area. An insulating film 170 made of silicon oxide (SiO ₂ ) or the like is formed on the extension 115. According to this configuration, on the n-electrode 140, the protective film 130 exists between the n-electrode 140 and the extension portion 115 of the translucent thin film p-electrode, and the current cross-sectional area flowing can be increased. The amount of energy absorption can be increased. As a result, the electrostatic withstand voltage is improved. In this configuration, a laminated structure of a protective film, a metal layer, and a protective film may be employed as in the second embodiment. Also in the present embodiment, as in the first embodiment, the protective film 130 may be a film that also functions to protect the semiconductor light emitting element 500 such as contamination, and the insulating film 170 is a translucent thin film p-electrode. It may be formed not only on the entire top surface of the extension 115 but also on substantially the entire top of the translucent thin film p-electrode 110. This structure can be applied to both wire bonding type and flip chip type light emitting elements.

  FIG. 8 is a cross-sectional view of the light emitting diode 600 of the sixth embodiment. This example is an example of a semiconductor light emitting device in which two electrodes are formed on two opposing surfaces of a semiconductor device using a conductive substrate 190 such as a silicon substrate to which a dopant is added. In the case of this light-emitting element, it can be applied to both a surface-emitting type that extracts light from a surface parallel to the main surface of the substrate and an edge-emitting type that extracts light from a surface perpendicular to the main surface, as in the above embodiment. It is. The n electrode 145 is formed on the entire back surface of the conductive substrate 190. Other layer configurations are the same as those of the embodiment shown in FIG. The protective film 134 is formed up to substantially the entire surface excluding the bump connection or wire bonding region of the p-electrode 150, the side wall of the element, and a part of the back surface of the conductive substrate 190. An extension 146 of the n-electrode 145 is formed on the entire upper surface of the protective film 134.

By adopting this structure, the p-electrode 150 and the n-electrode extension 146 face each other with the protective film 134 interposed therebetween. As a result, the cross-sectional area of the current flowing through the protective film 134 increases, the amount of surge energy absorbed increases, and the electrostatic withstand voltage improves. Also in this embodiment, a laminated structure of a protective film, a metal layer, and a protective film may be adopted as in the second embodiment. Also in the present embodiment, as in the first embodiment, the protective film 134 may be a film having a protective function such as contamination with respect to the semiconductor light emitting device 600, and further, an insulating material such as silicon oxide (SiO ₂ ). A film may be formed on the entire upper surface of the n-electrode extension 146.

  As described above, by using the present invention, the electrostatic withstand voltage can be drastically improved while maintaining the element chip (without specially adding a surge absorbing element or the like outside). In addition, as a result of the protection of electrostatic withstand voltage already achieved in the wafer or chip structure, it is not necessary to take measures against electrostatic withstand voltage in the manufacturing process, and the manufacturing efficiency is improved. According to the present invention, the electrostatic withstand voltage of a semiconductor element using a III-V group nitride compound semiconductor can be improved, which is a very effective technique.

  The present invention can be applied to semiconductor light emitting devices such as semiconductor lasers in addition to light emitting diodes. In addition, it can also be applied to electronic devices such as light receiving elements, solar cells, and transistors. By using the present invention, it is possible to improve the electrostatic withstand voltage of a semiconductor element using a III-V nitride compound semiconductor having a weak point in electrostatic withstand voltage.

Sectional drawing of the semiconductor light-emitting device based on Example 1 of this invention. The top view which illustrated the basic structure of the light emitting element. Sectional drawing of A direction view of the basic structure of a light emitting element. Sectional drawing of the light emitting diode which concerns on Example 2 of this invention. Sectional drawing of the semiconductor light-emitting device based on Example 3 of this invention. Sectional drawing of the semiconductor light-emitting device based on Example 4 of this invention. The top view of the semiconductor light-emitting device based on Example 4 of this invention. Sectional drawing of the light emitting diode which concerns on Example 5 of this invention. Sectional drawing of the light emitting diode which concerns on Example 6 of this invention. The characteristic view which showed the nonlinear resistance characteristic of the protective film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Semiconductor light emitting element 101 ... Sapphire substrate 102 ... Buffer layer 104 ... N-type contact layer (1st layer)
105 ... n-type semiconductor layer 106 ... light emitting layer 107 ... p-type layer 108 ... p-type contact layer 110 ... translucent thin film p-electrode (second electrode)
115. Extension (extension of translucent thin film p-electrode)
130, 133, 134 ... protective film 131 ... first protective film 132 ... second protective film 140 ... n electrode (first electrode)
143 ... Extension part (extension part of n electrode)
160 ... metal layer 170 ... insulating film

Claims (9)

A group III-V nitride semiconductor is used as a material for each layer, and at least the first electrode, the first conductivity type first layer to which the first electrode is connected, the second electrode, and the second electrode are connected. In a semiconductor device having a second layer of the second conductivity type,
Non-linear resistance characteristic that is composed of zinc oxide or a material containing zinc oxide that connects the first electrode and the second electrode and absorbs energy by rapidly decreasing the resistivity with respect to a voltage equal to or higher than a threshold voltage. A III-V nitride semiconductor device, characterized in that a protective film is provided. The first electrode is formed on an exposed region of the first layer, and the protective film is formed along a sidewall of each layer so as to connect the second electrode formed on the second layer and the first electrode. The III-V group nitride semiconductor device according to claim 1 , wherein the III-V group nitride semiconductor device is formed. 3. The group III-V nitride according to claim 2, wherein a metal layer in which an induced current is consumed as an eddy current loss when a current flows through the protective film is formed in the protective film. Semiconductor element. The first electrode is formed on an exposed region of the first layer, the protective film is formed on at least the first electrode, the second electrode is formed on the second layer, and the protective film is formed on the first layer. 2. The group III-V nitride semiconductor device according to claim 1 , wherein the III-V group nitride semiconductor device is formed to extend to a position facing the first electrode. The second electrode is formed on a plane of the second layer, the protective film is formed at least on a part of the second electrode, the first electrode is formed on the first layer, and 2. The group III-V nitride semiconductor device according to claim 1 , wherein the III-V group nitride semiconductor device is formed to extend to a position facing the second electrode through a protective film.   5. The protective film is also formed on a side wall of each layer, and the second electrode is formed to extend on the protective film to a position facing the first electrode. III-V group nitride semiconductor device described in 1.   6. The protective film is also formed on a side wall of each layer, and the first electrode is formed to extend on the protective film to a position facing the second electrode. III-V group nitride semiconductor device described in 1. The exposed portion of the one layer, in any one of claims 2 to 7, characterized in that each layer of the part of the plane of the first layer is a portion which is formed by removing The III-V group nitride semiconductor device described. Wherein the first electrode and the second electrode, any one of claims 1 to 7, characterized in that opposite to and is formed so as to sandwich the layers on different surfaces of the semiconductor element III-V group nitride semiconductor device described in 1.

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