JPH11340514A - Flip-chip optical semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To emit light at a high luminance with few short-circuits by providing a protective film covering the surface of nitride semiconductor layers with a laminate, comprising a first layer made of an insulating film, a metal layer formed on the first layer, and a second layer made of an insulating film and formed on the metal layer. SOLUTION: After forming an n-type nitride semiconductor film and a film of a p-type nitride semiconductor on a sapphire substrate 104, the p-type nitride semiconductor is etched in part to thereby expose the surface of the n-type nitride semiconductor layer. After forming electrodes 110, 111 and 112 on the p and n-type nitride semiconductors, a silicon oxide film is formed over the whole surface. Etching is effected, using the silicon oxide film as a mask to thereby expose part of the electrode surfaces, and an insulating film which is a first layer 101 is formed. Then, a platinum film is formed to thereby form a metal layer 102 on the layer 101. Furthermore, a second layer 103 of an insulating layer is formed on the layer 102 by processing the silicon oxide film by a plasma CVD method. As a result, a three-layered protective film is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flip-chip type optical semiconductor element which can be used as a light-emitting element for various indicators, a printer head of an optical printer, and a light-receiving element such as a solar cell. The present invention relates to a high-brightness flip-chip type optical semiconductor element in which a short circuit is extremely small irrespective of the positional accuracy even in the arrangement of (1).

[0002]

2. Description of the Related Art There is a flip-chip type optical semiconductor element in which an electrode of an LED chip is directly and electrically conductively fixed on an electrode of a driving substrate by using an Ag paste or solder. LED like this
The chip does not require the use of wires to establish conduction, and a relatively small LED chip can be mounted in a relatively simple process.

FIG. 4 is a schematic sectional view of such a flip-chip type optical semiconductor device. FIG. 4 shows an LED chip in which an n-type nitride semiconductor and a p-type nitride semiconductor are formed on a sapphire substrate 404 via a buffer layer 405. Part of the semiconductor is removed to expose the surface of the p-type and n-type nitride semiconductors, respectively, in order to establish conduction from the semiconductor surface side. A p-type electrode 411 and an n-type electrode 412 are formed on the surface of the p-type and n-type nitride semiconductors, respectively. Therefore, the p-type electrode 411 and the n-type electrode 4
Reference numerals 12 are formed on the same plane.

[0004] After an Ag paste or the like is applied on the electrode pattern of the driving substrate in advance, the LED chip is arranged with the electrode surface facing down. By curing the Ag paste, it is possible to fix the LED chip and to establish conduction between the electrode of the drive board and each electrode of the LED chip.

[0005] LED chips each having a length of 350 μm or less
The electrode on the ED chip may be as small as about 100 μm on a side. In this case, it is difficult to accurately arrange the LED chips using a die bonding device. Further, in the above-described flip-chip type optical semiconductor device, there are cases where semiconductor junctions having different polarities are exposed on the same surface side. Therefore, when connecting the electrode of the LED chip and the electrode pattern of the drive board via Ag paste or the like,
Ag paste may short between semiconductor junctions due to misalignment of the LED chips. In addition, the Ag paste viscosity and the surface tension with the LED chip surface cause Ag
The paste may creep up to the semiconductor junction, and similarly short-circuit the semiconductor junction. The short circuit not only lowers the light emission luminance but also destroys the light emitting element. Such a short circuit is caused by the protection film 40 such as silicon oxide except for the electrode surface.
The formation of 1 allows some control.

However, at present, there is a demand for smaller and higher-yield optical semiconductor devices, which is not sufficient, and further improvement is required. In particular, when an insulating film is formed, the number of short circuits is reduced, but a flip-chip type optical semiconductor device with a sufficient yield cannot be obtained. Accordingly, an object of the present invention is to provide a flip-chip type optical semiconductor device capable of emitting high luminance light with less short circuit.

[0007]

According to the present invention, a positive electrode and a negative electrode are provided on the same plane side of a nitride semiconductor formed on a light-transmitting insulating substrate, and the nitride semiconductor is formed except for an exposed portion of the electrode surface. This is a flip-chip type optical semiconductor device having a protective film covering a layer surface. In particular, the protective film has at least a three-layer structure of a first layer made of an insulating film, a metal layer on the first layer, and a second layer made of an insulating film on the metal layer.

Thus, the insulating film can be formed on the semiconductor junction and the like with good controllability, and the short-circuit can be made extremely small even when the flip-chip type optical semiconductor element is electrically connected. That is, by forming a metal layer (including an alloy), it is possible to prevent the conductive member constituting the conductive paste from entering through the insulating coating and to prevent a short circuit. Further, the light-emitting element can efficiently emit the emission wavelength emitted from the light-emitting element to the outside, or can be a light-receiving element that can efficiently absorb external light into the semiconductor.

According to a second aspect of the present invention, the first layer and / or the second layer are selected from silicon oxide, titanium oxide, niobium oxide, hafnium oxide, aluminum oxide, zirconium oxide, silicon nitride, and polyimide. At least one kind. Thus, a flip-chip type optical semiconductor device having higher reliability can be obtained.

According to a third aspect of the present invention, the metal layer forms a part of the electrode. Thus, a highly reliable flip-chip type optical semiconductor device can be obtained with a relatively simple configuration while simplifying the process of the protective film.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various experiments, the present inventor has found out that a highly reliable flip-chip type optical semiconductor device can be obtained by using a specific structure for a film covering a nitride semiconductor device. Invented the invention.

That is, it is considered that it is difficult to form a dense and defect-free thin film of the inorganic insulating film, and that the inorganic insulating film is short-circuited by a conductive adhesive used for electrical connection of the flip-chip type optical semiconductor element. More specifically, a conductive member such as Ag forming the conductive adhesive is ionized by moisture or the like in the surrounding environment. In some cases, the ionized metal migrates in the inorganic insulating film due to energization with the nitride semiconductor and causes a short circuit. Not only the function of the semiconductor is reduced due to the short circuit, but also the semiconductor element may be destroyed. In particular, a short circuit at the semiconductor junction is considered to have a particularly large effect on the nitride semiconductor device. According to the present invention, a short circuit formed at a semiconductor junction or the like through an insulating member can be prevented by using a protective film having a metal film sandwiched between insulating films. Note that such a problem is the same not only in the light emitting element but also in the light receiving element.

Hereinafter, a specific embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a sapphire substrate 10.
After an n-type nitride semiconductor and a p-type nitride semiconductor are respectively formed on 4, the p-type nitride semiconductor is partially etched to expose the surface of the n-type nitride semiconductor layer. After the electrodes 110, 111, and 112 are formed on the p-type and n-type nitride semiconductors, silicon oxide is formed over the entire surface by a plasma CVD method. By etching using silicon oxide as a mask, a part of the electrode surface was exposed to form an insulating film as the first layer 101. Next, platinum is formed by a sputtering method, and the metal layer 102 is formed over the first layer.
Further, in the same manner as in the first layer 101, silicon oxide was formed as an insulating second layer 103 by a plasma CVD method to form a three-layer protective film. The electrode of the formed flip-chip type optical semiconductor element was electrically connected to the electrode pattern of the drive circuit board using a Cu-containing epoxy resin. When a current is supplied from the drive circuit, the LED chip emits light. The light from the LED chip may be transmitted directly through the sapphire and extracted to the outside, or may be reflected by the metal layer forming the protective film and extracted from the sapphire. Therefore, the emission wavelength from the LED chip can be emitted with high efficiency. Hereinafter, each configuration of the present invention will be described in detail.

(Protective Film) The protective film of the present invention comprises at least a first layer 101 made of an insulating film, a metal layer 102, and a second layer made of an insulating film 103. Especially,
The protective film is to prevent at least the semiconductor junction of the optical semiconductor element from being in contact with a conductive paste or solder used when the flip-chip type optical semiconductor element is conducting. Therefore, each layer preferably has the following characteristics.

(First Layers 101, 201, 301) Since the first layer can be formed in contact with the nitride semiconductor, it is preferable that the first layer has good adhesion to the nitride semiconductor. Further, an insulating film with high insulating property is preferably used for forming the metal layer 102 over the first layer 101. The first layer 101 can efficiently reflect the wavelength at which the light emitting element emits light, or can efficiently reflect the wavelength at which the light receiving element receives light, thereby increasing the light use efficiency. Specifically, the reflectance can be improved by setting the thickness of the first layer 101 to 1/4 times the emission wavelength of the light-emitting element or the light-receiving wavelength of the light-receiving element. In the case where the emission wavelength emitted from the light emitting element is reflected by the metal layer 102, the first layer 101 is transparent to at least the emission wavelength emitted from the light emitting element and the light reception wavelength received by the light receiving element. It is preferable to use a high layer.

Materials used for the first layer 101 include metal oxides and metal nitrides such as silicon oxide, titanium oxide, niobium oxide, hafnium oxide, aluminum oxide, zirconium oxide and silicon nitride, and polyimide. And the like. When the first layer 101 is an inorganic insulating film, a small optical semiconductor element can be formed with good controllability by using a sputtering method, various CVD methods, or the like. In particular, in order to form a dense inorganic insulating film, it is preferable to use a plasma CVD method.

(Metal layers 102, 202, 302) The metal layer 102 has a function of substantially preventing metal ions or the like from entering from the outside via the second layer 103 constituting the protective film during conduction. is there. The metal layer 102 can be formed as a thin film with good controllability by a sputtering method, a vacuum evaporation method, or the like, and can be easily formed as a film with few defects. Further, by selecting a metal (including an alloy or a laminate) that efficiently reflects the wavelength transmitted through the first layer 101, it is possible to improve the light condensing property and the like, and to increase the light extraction efficiency.

The metal layer 102 stops the intrusion of ions from the outside. Alternatively, various kinds of metals can be selected as long as they can prevent the intrusion of the conductive paste, fillers and solder constituting the conductive paste. Preferred examples of the material of the metal layer include nickel, platinum, gold, aluminum, tungsten, molybdenum, and alloys and laminates thereof.

Since the metal layer can suitably prevent ion migration, it is preferable that the metal layer itself does not easily ionize. In particular, silver has high conductivity and good reflectivity for light corresponding to the band gap of the nitride semiconductor. However, it is preferable to use a metal element excluding silver, which easily causes ion migration. Also,
The thickness of the metal layer 102 is preferably about 100 to several microns in consideration of the wavelength of light emitted from the light-emitting element and miniaturization. As long as the metal layer 102 is not short-circuited, it may be formed so as to cover the entire circumference of the nitride semiconductor or may be formed into a plurality of divided shapes.

When divided into a plurality of parts, a part of a p-type or n-type electrode can be formed. Thus, the metal layer 302 can be formed simultaneously with the formation of the electrodes. Therefore, a plurality of masks and an etching step can be simplified, and the number of steps can be reduced. When the metal layer 302 specifically functions as an electrode of a p-type nitride semiconductor, the metal layer 302 may be formed of a metal element such as nickel, cobalt, gold, or platinum in consideration of ohmic contact and the like. preferable. Similarly, in the case of functioning also as an electrode of an n-type nitride semiconductor, the electrode is preferably formed of a metal element such as tungsten, aluminum, or titanium. Further, when a nitride semiconductor is used for an LED having a double heterostructure via an active layer, the active layer is covered with a metal layer via an insulating layer since light emitted from an end face of the active layer is particularly large. Thereby, the luminous efficiency can be further improved.

(Second Layer 103) The second layer 103 is a metal layer 1
02 is an insulating film provided to electrically insulate the outside from the nitride semiconductor. Therefore, when directly formed on the metal layer 102, the metal layer 1
02 and high insulation properties are required. As the material used for the second layer 103, similarly to the first layer 101, various inorganic materials such as metal oxides and metal nitrides, and various organic resins can be selected. More specifically, preferred examples include silicon oxide, titanium oxide, niobium oxide, hafnium oxide, aluminum oxide, zirconium oxide, silicon nitride, and polyimide resin.
In the case where the second layer 103 is an inorganic insulating film, the tendency to short-circuit is reduced as the layer is densely formed, but it takes a long time to form the layer densely.

On the other hand, the second layer 103 may be arranged at the outermost periphery of the flip-chip type optical semiconductor device. In the case of such a second layer 103, an insulating organic substance such as polyimide can be used in order to prevent damage to the protective film during mounting. Thereby, the reliability can be further improved. Specifically, after the nitride semiconductor is formed on a sapphire substrate or the like, the nitride semiconductor is divided into individual nitride semiconductor elements by scribing or the like on an adhesive sheet. The adhesive sheet is stretched so that the divided nitride semiconductor elements can be picked up, and the individual semiconductor elements are pushed up from below the adhesive sheet by push-up pins, and are attracted to the collet. On the other hand, a conductive paste such as an Ag paste is applied to the electrodes on the drive substrate side to be mounted. The nitride semiconductor element adsorbed by the collet is placed on the conductive paste, and the conductive adhesive is cured. Thus, the nitride semiconductor element can be arranged and fixed on a desired driving substrate or the like.

In the case of a nitride semiconductor device, a nitride semiconductor is formed on a relatively hard sapphire substrate or the like. Therefore, although the strength is relatively high on the substrate side, the push-up pin pushes up the electrode surface side on which the insulating coating is formed when adsorbing with the collet. Then, the semiconductor surface (the nitride semiconductor side with respect to the sapphire substrate) is flip-chip bonded to the conductive portion of the wiring substrate via a conductive adhesive.

In this case, although the insulating film is formed on the nitride semiconductor surface, the nitride semiconductor end surface, the exposed substrate surface, and the like in order to prevent short-circuit failure, the occurrence rate of short-circuit failure is considerably high. Tends to be higher. The cause is that when the light emitting surface is the substrate surface, the substrate is hard, so that the push-up pins are less likely to cause scratches and cracks. In particular, when the nitride semiconductor surface is pushed up by a push-up pin, it is considered that the protection film is easily damaged, cracked, or the like, so that a short-circuit occurrence rate is high.

Therefore, in the case where an insulating film made of an organic resin is formed as the second layer 103 in particular, in a flip chip bonding type nitride semiconductor device, scratches on the nitride semiconductor surface and cracks in the insulating film due to push-up pins are prevented. In addition, a highly reliable nitride semiconductor device without short circuit failure can be obtained.

That is, by using the organic insulating film as the second layer 103, the physical impact of the push-up pins from the lower part of the adhesive sheet at the time of mounting on the wiring board is alleviated, and the insulating film may be broken to cause a short circuit. Can be effectively prevented. The specific film thickness when a polyimide thin film is used for the second layer 103 is 1 to 10 μm in terms of relaxation of a physical force received when the second layer 103 is pushed up by the push-up pin and withstand voltage of the insulating film. Is preferred. When the transmittance at the main emission wavelength of the polyimide-based thin film is 60% or less, light leakage from the end face of the nitride semiconductor element is suppressed, and variation in optical characteristics is reduced. Therefore, it is more preferable because the stability of the light distribution characteristics can be obtained.

(Optical Semiconductor Element) The optical semiconductor element of the present invention is a light receiving element or a light emitting element made of a nitride semiconductor.
It can be made of a nitride semiconductor formed on a light-transmitting insulating substrate and having at least a semiconductor junction. Specifically, a nitride semiconductor can be formed over a light-transmitting insulating substrate by an MOCVD method or an HVPE method. Examples of such a light-transmitting insulating substrate include gallium nitride, sapphire (Al ₂ O ₃ ), spinel (MgAl ₂ O ₄ ), and the like. Examples of the semiconductor junction include a pn junction in addition to a MIS junction and a PIN junction. Further, depending on the characteristics of the optical semiconductor element, a homo or double hetero structure can be obtained. Furthermore, a single quantum well structure or a multiple quantum well structure can be used.

By short-circuiting the pin junction and the pn junction,
Significant damage to semiconductor properties. Therefore, the present invention works effectively. The emission wavelength and the reception wavelength of the optical semiconductor element can be variously selected from the ultraviolet light to the red region depending on the material of the semiconductor and the degree of mixed crystal thereof.

In order to form a nitride semiconductor with good crystallinity, it is preferable to use a sapphire substrate. GaN on this sapphire substrate to reduce lattice mismatch,
By forming a buffer layer of AlN or the like and forming a nitride semiconductor having a pn junction or the like thereon, a light-emitting element or a light-receiving element having excellent semiconductor characteristics can be formed. Forming the substrate with sapphire is particularly preferable because the hardness is high, the substrate itself has a light-transmitting property, and the entry of moisture or the like from the outside can be prevented.

The nitride semiconductor shows n-type conductivity without being doped with an impurity.
It is preferable to appropriately introduce Ge, Se, Te, Sn, and the like. Further, double doping in which an n-type dopant and a small amount of a p-type dopant are doped can also be performed. By changing the type and doping amount of these dopants, the carrier density can be controlled and the electric resistance can be reduced. On the other hand, when forming a p-type nitride semiconductor,
Type dopants Zn, Mg, Be, Ca, Sr, B
a and the like are doped. Since the gallium nitride semiconductor is difficult to reduce the resistance only by doping the p-type dopant, the resistance can be reduced by introducing a low-speed electron beam, irradiating a plasma, or performing a heat treatment after introducing the p-type dopant.

In order to form a pair of electrodes on the semiconductor exposed surface side, each semiconductor is preferably etched into a desired shape. Examples of the etching include dry etching and wet etching. Examples of dry etching include reactive ion etching, ion milling,
Focused beam etching, ECR etching and the like can be mentioned. For wet etching, a mixed acid of nitric acid and phosphoric acid can be used. However, it goes without saying that a mask is formed in a desired shape using a material such as silicon nitride or silicon oxide before etching. Hereinafter, embodiments of the present invention will be described in detail, but it is needless to say that the present invention is not limited thereto.

[0032]

(Example 1) A nitride semiconductor was formed by MOCVD using the C surface of washed sapphire as a film forming surface. The sapphire substrate 104 is placed in the film forming apparatus and 6
While heating to 50 ° C., a buffer layer 105 was formed by flowing TMG (trimethyl gallium) gas and nitrogen gas as source gases and hydrogen gas as carrier gas. Once the introduction of the raw material gas is stopped, the film formation temperature is raised to 1150 ° C., and silane is added as an n-type dopant gas to TMG gas, nitrogen gas, and hydrogen gas to form a 5 μm-thick n-type gallium nitride layer 106. did. Next, the supply of TMG gas is stopped,
After lowering the film forming temperature to 800 ° C., TMG gas, TM
A (trimethylaluminum) gas, a nitrogen gas, and a hydrogen gas were supplied to form a 3 nm-thick indium gallium nitride film as the light-emitting layer 107.

Next, the supply of the raw material gas was stopped and the film forming temperature was raised to 1050 ° C., and then again TMG gas, TMA gas, nitrogen gas as the raw material gas, hydrogen gas as the carrier gas, and cyclopentadiethyl as the impurity gas. A p-type cladding layer 108 having a thickness of 300 ° is formed by adding magnesium.

The p-type contact layer 109 having a thickness of 1500 ° is formed on the p-type cladding layer 108 in the same manner as the formation of the p-type cladding layer except that the supply of the TMA gas is stopped. (Note that the semiconductor layer to be a p-type nitride semiconductor is heat-treated at 400 ° C. or more after film formation.) Thus, a nitride semiconductor having a double hetero structure was formed via the active layer.
In order to form electrodes on the same side of the semiconductor wafer, a mask is used to partially etch the n-type contact layer while partially leaving the active layer, the p-type cladding layer, and the p-type contact layer. Similarly, each of the LED chips is etched to a size that can be separated as far as the sapphire substrate. After the etching, an island-shaped nitride semiconductor layer is formed on the sapphire substrate.

Platinum was formed by sputtering at 500 ° as an electrode 110 which was in contact with the p-type contact layer 109 and covered the entire surface. On this electrode 110, 100
Platinum was formed to a thickness of 0.7 μm as a p-type electrode 111 of μm square. On the n-type contact layer 106, tungsten / aluminum is used as an n-type electrode 112 having a diameter of 100 μm.
The film was formed as 00 ° / 0.7 μm. Thus, a pair of positive and negative electrodes 1 are formed on the same plane on the island-shaped nitride semiconductor.
11 and 112 are formed.

A semiconductor wafer was placed in a plasma CVD apparatus to form the first layer 101 on each of the p-type and n-type electrodes on which each nitride semiconductor was formed. A silicon oxide film was formed on the entire surface of the semiconductor wafer using silane gas and nitrogen oxide gas as source gases. After forming the silicon oxide film, the p-type electrodes 111 and n are taken out from the plasma CVD apparatus and dry-etched using a resist mask.
The surface of the mold electrode 112 was exposed. By removing the resist mask, a silicon oxide film to be the first layer 101 was formed on the semiconductor wafer.

Subsequently, the semiconductor wafer is placed in a sputtering apparatus, and sputtering is performed using platinum as a target to form a metal layer 102 having a thickness of 500.degree.
Of platinum was deposited. P-type electrode 1 by lift-off
11 and the surface of the n-type electrode 112 were exposed. further,
The silicon oxide of the second layer 102 is formed again under the same conditions as the first layer 101. After that, the mask formed on the p-type electrode 111 and the n-type electrode 112 is removed. Thus, the surface of the nitride semiconductor except for the surfaces of the p-type electrode 111 and the n-type electrode 112 and the sapphire substrate 104 has silicon oxide 1
01, platinum 102 and silicon oxide 103 are formed. By separating the semiconductor wafer, flip-chip type LEDs can be obtained.

Out of the obtained LED chips, 1,400 chips were die-bonded to a drive circuit on which a pair of electrodes each having a distance of about 100 μm was formed, using an Ag paste. When current is applied to each LED, sapphire substrate 1
Light was emitted through the light-emitting element No. 04, and all light emission was possible.

Comparative Example 1 A flip chip as shown in FIG. 4 was prepared in the same manner except that the thickness of the first layer was changed to the same thickness as the thickness of the protective film in Example 1 instead of providing the metal layer and the second layer. A shaped LED was formed. In the same manner as in the first embodiment,
1400 LEDs were die-bonded using the g paste. When current was applied to each LED, there were 5 lamps that did not light. Eight light emission luminances were extremely dark. When the unlit lamp was examined using a focused ion beam processing apparatus, A was detected through the protective film.
g was leaking because it penetrated. In addition, when the average luminance excluding the one in which the emission luminance was extremely dark was set to 100, the average luminance of Example 1 was 121.

(Embodiment 2) In Embodiment 2, the LE shown in FIG.
As in D, a polyimide film was used instead of forming the second layer 203 with silicon oxide. A flip-chip LED was formed in the same manner as in Example 1 except that the second layer 203 was formed by applying and curing a polyimide film. L obtained
When ED was measured in the same manner as in Example 1 and Comparative Example 1, almost the same results as in Example 1 were obtained. Example 2
In the case of Example 1, the deterioration with the lapse of time tends to be smaller than that in Example 1.

(Embodiment 3) The thickness of the metal layer 302 is set to 0.7
As shown in FIG. 3, the flip-chip type L was formed in the same manner as in Example 1 except that the p-type electrode was integrally formed as shown in FIG.
An ED was formed. The obtained LED was able to obtain almost the same reliability as that of Example 1 although the process was simplified.

[0042]

The present invention relates to a flip-chip type optical semiconductor device using a nitride semiconductor on a sapphire substrate.
By covering with a protective film having a layer structure, it is possible to improve the light emission luminance and to obtain a flip-chip type optical semiconductor element with few short circuits.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a flip-chip type optical semiconductor device of the present invention.

FIG. 2 is a schematic cross-sectional view in which another flip-chip type optical semiconductor device of the present invention is arranged on a driving substrate.

FIG. 3 is a schematic cross-sectional view of another flip-chip type optical semiconductor device of the present invention.

FIG. 4 is a schematic cross-sectional view of a flip-chip type optical semiconductor device shown for comparison with the present invention.

[Explanation of symbols]

100, 200, 300: Optical semiconductor element 101, 201, 301: First made of inorganic insulating film
Layers 102, 202: metal layers 103, 303: second layer made of an inorganic insulating film 104, 204, 304: translucent insulating substrate 105, 205, 305: buffer layers 106, 206, 306: n-type contact layer 107, 207, 307: active layer 108, 208, 308: p-type cladding layer 109, 209, 309: p-type contact layer 110, 210, 310 ... Electrodes 111, 211 formed on a p-type semiconductor 111, 211, p-type electrodes 112, 212, 312 ... n-type electrode 203 ... second layer made of an organic insulating film 214 ... formed on a driving substrate Electrode pattern 215... Driving substrate 302... Metal layer constituting p-type electrode 400. Optical semiconductor element 401. First layer made of inorganic insulating film 404. Substrate 405: Buffer layer 406: N-type contact layer 407: Active layer 408: P-type cladding layer 409: P-type contact layer 410: Electrode formed on p-type semiconductor 411: p-type electrode 412: n-type electrode

Claims (3)

[Claims] 1. A protective film in which a positive electrode and a negative electrode are provided on the same plane side of a nitride semiconductor formed on a translucent insulating substrate, and the surface of the nitride semiconductor layer is covered except for an exposed portion of the electrode surface. Wherein the protective film comprises a first layer made of an insulating film, a metal layer on the first layer, and a second layer made of an insulating film on the metal layer. A flip-chip type optical semiconductor device having at least a three-layer structure. 2. The method according to claim 1, wherein the first layer and / or the second layer is at least one selected from silicon oxide, titanium oxide, niobium oxide, hafnium oxide, aluminum oxide, zirconium oxide, silicon nitride, and polyimide. The flip-chip type optical semiconductor device according to the above. 3. The flip-chip type optical semiconductor device according to claim 1, wherein said metal layer forms a part of said electrode.