JP2005072339A - Light source, its manufacturing method, and projection type display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a chip from deteriorating in the direct cooling of the chip with a fluid, relax the thermal stress caused on the chip surface, and prevent the short circuit between electrodes through the fluid. <P>SOLUTION: An LED 1 comprises a chip 12 and a mechanism for directly cooling the chip 12 with a cooling fluid F. After mounting the chip, an inorganic insulating material is deposited on the surface of the chip 12 and the base 10 to cover the chip 12 and the outer surface of the base 10 to be exposed to the fluid F entirely with a protective film 17 composed of a light transparent insulating film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light source device, a manufacturing method thereof, and a projection display device including the light source device.

In conventional projectors (projection display devices), a halogen lamp has been used as a light source in the past, and a high-pressure mercury lamp (UHP) having high luminance and high efficiency has been used in recent years. A light source using UHP, which is a discharge lamp, requires a high-voltage power circuit, is large and heavy, and hinders the reduction in size and weight of the projector. Further, although it has a longer life than a halogen lamp, it still has a short life, and it is almost impossible to control the light source (fast lighting, extinguishing, modulation), and it takes a long time to start up.
In recent years, therefore, LEDs have attracted attention as a new light source. LEDs are ultra-compact, ultra-light, and have a long life. In addition, by controlling the drive current, it is possible to freely turn on / off and adjust the amount of emitted light. In this respect, it is also promising as a light source for projectors, and application development has already started for small and portable small screen projectors.

By the way, in order to protect the chip, the LED is usually covered with a translucent resin. However, since the resin is generally low in thermal conductivity, most of the heat generated in the chip is the bottom surface of the LED package. Heat is dissipated through (metal base) and lead wires. However, as the brightness and output of the LED increase, sufficient heat dissipation cannot be obtained with the above structure.
Therefore, a structure in which the LED chip is directly cooled by a liquid such as alcohol filled in the container (see Patent Document 1), or an LED chip is infiltrated into an insulating and inert translucent liquid, and the liquid flows in and out. Thus, a structure (see Patent Documents 2 to 4) for efficiently cooling the chip has been proposed. In this structure, higher cooling performance can be obtained by forcibly circulating a low-temperature fluid.
Japanese Patent Laid-Open No. 11-163410 JP 2001-36148 A JP 2001-36149 A JP 2001-36153 A

However, the high-luminance and high-power LED chips used for projector light sources and the like generate a large amount of heat, and it is necessary to flow a considerable amount of liquid to cool them. This is a factor that adversely affects the reliability of the LED.
That is, if the LED chip is forcibly cooled directly, a large temperature difference will be generated inside the LED chip. However, since each layer constituting the chip has a different coefficient of thermal expansion, stress due to thermal deformation is generated by this temperature difference. . Such stress causes a defect in the chip layer and shortens the lifetime.

In the above structure, depending on the fluid used, a short circuit may occur between the electrodes, or the element may deteriorate. For example, when the chip is directly cooled by a liquid, a filler or the like may be mixed in the liquid in order to increase the cooling efficiency. In this case, the liquid becomes conductive due to the filler or the like, and a short circuit occurs between the electrodes. . Further, when H ₂ O or the like is used as the fluid, the chip may be deteriorated by a chemical reaction with the fluid.
Further, in the structure in which the wire bonding is performed by face-up mounting, there is a possibility that the joint between the electrode and the wire may be peeled off due to the pressure of the fluid.
Therefore, in order to put the chip direct cooling type LED by fluid into practical use, it is necessary to solve these problems.

  The present invention has been made in order to solve the above-described problems. The present invention alleviates the thermal stress on the chip surface caused by cooling, and short-circuits between electrodes via the cooling fluid, or causes deterioration of the chip due to the fluid. It is an object of the present invention to provide a light source device that can be prevented, a method for manufacturing the light source device, and a projection display device including the light source device.

  In order to achieve the above object, a light source device of the present invention is a light source device comprising a solid light source and a mechanism for directly cooling the solid light source with a cooling fluid, and at least the solid light source for the fluid is provided. A protective film made of a light-transmitting insulating material is provided on the outer surface including the electrode of the solid-state light source so as to cover the entire exposed surface.

  The present invention prevents the deterioration of the solid light source due to the chemical reaction with the cooling fluid, the short circuit between the electrodes via the fluid, etc. by providing a protective film for the solid light source and the electrode of the solid light source. It is a thing. As an example in which a protective film is provided on a solid light source as described above, for example, there is a structure disclosed in Japanese Patent Application Laid-Open No. 7-202269, but this technique is based on heat generated in the process of manufacturing a solid light source on a substrate. The purpose is to relieve stress, and the protective film is formed before electrode bonding. For this reason, it is necessary to remove the protective film on the electrodes at the time of bonding, and it is impossible to prevent a short circuit between the electrodes through the fluid. In contrast, in the present invention, a protective film is also provided on the electrode of the solid light source, and the outer surface of the portion of the solid light source (including the electrode of the solid light source) that is exposed to the cooling fluid is entirely covered with the protective film. Therefore, such an electrical short circuit can be reliably prevented.

In this configuration, since the solid light source (including the electrode) is completely isolated from the cooling fluid, they are not deteriorated by a chemical reaction with the cooling fluid.
In addition, when a protective film is arranged between the fluid and the solid light source in this way, the temperature change (temperature gradient) generated at the interface with the fluid is partially absorbed by the protective film, so the temperature generated on the surface of the solid light source The gradient is smaller than when there is no protective film. For this reason, the thermal stress generated between the layers of the solid light source can be relaxed as compared with the conventional case, and the lifetime of the element can be extended.

  Moreover, in this structure, since the junction part of an electrode can be fixed by covering the electrode part of a solid light source with a protective film, the reliability of an element increases. In particular, in the structure in which wire bonding is performed by performing face-up mounting, the joint portion between the electrode of the solid light source and the wire is easily peeled off by the pressure of the fluid, and thus the effect of the present invention is great.

In the present invention, the protective film is preferably provided so as to cover an exposed surface of the base on which the solid light source is mounted with respect to the fluid.
Thus, by providing a protective film so as to cover not only the solid light source but also the surface of the base that supports the solid light source, the base is prevented from being altered or corroded due to a chemical reaction with the cooling fluid. be able to. In addition, when the base is made of metal, a configuration in which the base itself is used as an electrode of a solid light source is also assumed, but even in such a case, the surface of the base is used as in the present invention. By covering with a protective film, it is possible to reliably prevent a short circuit between the electrode and the base, or a bonding wire (in the case of face-up mounting) and the base.

The protective film is preferably made of an inorganic material.
An organic material can be used for the above-described protective film. However, when the emission intensity is increased, the protective film itself is deteriorated by the emitted light, and there is a possibility that the insulating property and the transparency are lowered. For this reason, the reliability of an element can be improved by comprising a protective film with an inorganic material without such photodegradation.

In the present invention, it is preferable that the protective film is a laminated film of a plurality of insulating films having different refractive indexes, and these insulating films are laminated in the descending order of the refractive index with respect to the solid light source.
Normally, the constituent material of a solid light source is made of a material having a high refractive index (for example, a refractive index of about 3). Therefore, when this is directly exposed to a fluid (for example, a refractive index of about 1.5), much of the emitted light is emitted. Total reflection occurs at the interface between the solid light source and the fluid. The light reflected in this way does not contribute to illumination, but is converted into heat, thereby deteriorating the light emission characteristics of the element. For this reason, in order to increase the light extraction efficiency, it is necessary to dispose a material having an intermediate refractive index between the solid light source and the fluid (in the present invention, the protective film is configured as this intermediate material). However, as described above, since the difference in refractive index between the solid light source and the fluid is extremely large, it is not possible to obtain a sufficient effect if only one film is formed between the solid light source and the fluid. For this reason, it is preferable to design the film material so that the protective film is a laminated film and the refractive index decreases in order from the solid light source side. When the refractive index is gradually changed from the solid light source side to the fluid side in this way, each boundary surface (the interface between the solid light source and the insulating film, the interface between the adjacent insulating films, the interface between the insulating film and the fluid) Then, the critical angle at which total reflection occurs increases, and the ratio of light that is totally reflected is small, that is, the light extraction efficiency increases.

The film thickness and the number of layers of the insulating film placed between the solid light source and the fluid can be freely determined from the viewpoint of insulation, heat dissipation, productivity, etc. Sufficient performance can be demonstrated without loss. For example, when the protective film is a laminated film in which first, second, and third three insulating films are laminated in order from the solid light source side, for example, the first insulating film is formed of TiO ₂ , Ta ₂ O. ₅ , ZnO, ZrO ₂ , MgO, Al ₂ O _{3 for} the _second insulating film, and SiO ₂ , MgF ₂ for the third insulating film. Removal is possible. Note that each insulating film may be formed of one kind of material, and may include some of the above-described materials.

In the present invention, the cooling fluid is preferably made of an inorganic material.
An organic material can be used for the cooling fluid, but when the emission intensity increases, the cooling fluid itself may be deteriorated by the emitted light. Further, when a material having a photocatalytic action (for example, TiO ₂ or the like) is used for the protective film, the degree of deterioration is further increased. For this reason, the reliability of an element can be improved by comprising the fluid for cooling with the inorganic material which does not have such light degradation.

In the present invention, the cooling fluid is preferably made of a liquid material. Of course, a gas (for example, an inert gas such as N ₂ ) can be used as the fluid. However, by using a liquid material having a higher thermal conductivity (for example, silicon oil), the heat dissipation efficiency can be improved. it can.
In the present invention, the thickness of the protective film can be arbitrarily determined from the viewpoints of insulation and heat dissipation. However, if the film thickness is 0.8 μm or more and 1.5 μm or less, the effect of the present invention is achieved. You can get enough.

  The light source device manufacturing method of the present invention is a light source device manufacturing method including a solid light source and a mechanism for directly cooling the solid light source with a cooling fluid, and the solid light source is mounted on a base. And a protective film for forming a translucent protective film made of an insulating material on the outer surface including the electrode of the mounted solid light source so that at least the exposed surface of the solid light source with respect to the fluid is covered at least And a forming step.

  In this manufacturing method, the protective film is formed after the mounting process of the solid light source, so that the entire surface exposed to the cooling fluid of the solid light source (including the electrode) is covered with the protective film. For example, in the element disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-202269, the protective film is formed before the mounting process, so that it is necessary to remove the protective film located on the electrode during mounting. Therefore, at least in this electrode portion, the effects of the light source device of the present invention described above (that is, the deterioration of the solid light source due to the chemical reaction with the fluid, the mitigation of thermal stress generated near the surface of the solid light source during cooling, the fluid Prevention of short-circuit between electrodes and improvement in bonding strength) cannot be obtained. On the other hand, in this method, since the protective film can be provided also on the electrode of the solid light source, the outer surface of the solid light source in the portion exposed to the cooling fluid is all covered with the protective film. The effect of can be ensured.

In the protective film forming step, the protective film is preferably formed so as to cover an exposed surface of the base with respect to the fluid.
In this way, the protective film is formed so as to cover not only the surface of the solid light source but also the surface of the base supporting the solid light source, thereby preventing the base from being altered or corroded due to a chemical reaction with the cooling fluid. Can be prevented. In addition, when the base is made of metal, a configuration in which the base itself is used as an electrode of a solid light source is also assumed, but even in such a case, the surface of the base is used as in the present invention. By covering with a protective film, it is possible to reliably prevent a short circuit between the electrode and the base, or a bonding wire (in the case of face-up mounting) and the base.

The protective film is preferably made of an inorganic material. Thereby, deterioration of the protective film due to the light emitted from the solid light source can be prevented.
In the protective film forming step, it is preferable to form at least a protective film located at the interface with the solid light source by vapor deposition.
As a method for forming the protective film, various film forming methods such as a vapor deposition method (sputtering method, plasma CVD method, EB vapor deposition method, etc.) and a liquid coating method (sol-gel method, SOG (Spin On Glass) method, etc.) are used. Although it can be used, the film formed by the vapor deposition method (deposition film) is superior in terms of uniformity and denseness to the film formed by the liquid coating method (coating film). In addition, when a high insulating property is required for the protective film, a vapor deposition film is more suitable than a coating film.

In the protective film forming step, the protective film is preferably formed by a rotational oblique vapor deposition method (that is, a method of depositing an insulating material from an oblique direction with respect to a solid light source while rotating the base).
According to this method, a film can be uniformly formed on the entire surface of the solid light source. In particular, when wire bonding is performed with a solid-state light source mounted face-up, there is a risk that a protective film will not be sufficiently formed on the shadowed portion of the bonding wire. Can be avoided. In addition, in a semiconductor light emitting device such as an LED, in order to increase the light extraction efficiency, the base is provided with a concave portion (for example, a concave portion having a tapered inclined surface whose opening area increases as the distance from the base surface increases) A structure in which a solid light source is arranged has already been developed. However, when the rotational oblique deposition method is applied to this structure, a protective film having a sufficient thickness must also be formed on the inner wall surface of the recess. Can do.

  In the protective film forming step, it is preferable to stack a plurality of insulating films having different refractive indexes in order from the one having the highest refractive index. Thereby, the extraction efficiency of emitted light can be improved.

Further, when the solid-state light source is face-down mounted (flip chip mounting) on the base in the mounting step, at least a part of the protective film may be formed by a liquid coating method in the protective film forming step. preferable.
As described above, a vapor deposition method capable of forming a denser film is suitable for forming the protective film, but a slight gap is generated between the solid light source and the base as in face-down mounting. In some cases, the vapor deposition method cannot form a sufficient film in the gap. Therefore, in such a case, a liquid coating method that can form a film even in a small gap is suitable.

  However, since the coating film has a problem in terms of denseness, for example, a protective film is formed by laminating a plurality of insulating films, a part of the insulating film is formed by a coating method, and another insulating film is formed by a vapor deposition method. It is preferable to adopt a method such as forming. In this case, in order to securely protect the solid light source with a dense film, an insulating film disposed closest to the solid light source is formed by vapor deposition, and the insulating film disposed farthest from the solid light source is applied with liquid. It is desirable to form by the method. In addition, when a part of the protective film is formed by the liquid coating method in this way, the thickness of the protective film formed by the liquid coating method is set to 0.3 μm or less in order to prevent generation of cracks. It is desirable.

According to another aspect of the present invention, there is provided a projection display device comprising: the above-described light source device; a light modulation device that modulates light emitted from the light source device; and a projection lens that projects the modulated light. To do.
According to this configuration, by providing the above-described light source device, it is possible to provide a bright and reliable projection display device.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a sectional view showing a schematic configuration of a semiconductor light emitting device (LED) which is an example of a light source device according to the first embodiment of the present invention, and FIG. 2 is a main part of a solid light source (LED chip) provided in the LED. FIG. 3 is a schematic process diagram for explaining the LED manufacturing method. In all the drawings below, the film thicknesses and dimensional ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

As shown in FIG. 1, the light source device 1 of the present embodiment is obtained by mounting an LED chip 12 as a solid light source face-up on a metal base 10.
The chip 12 is a semiconductor chip having a double hetero structure in which an active layer made of, for example, AlGaInP is sandwiched between n-type and p-type clad layers, with an n-side electrode provided on the n-type clad layer facing down, Ag It is mounted on the base 10 with paste. The chip size is, for example, 1 mm × 1 mm.

  The base 10 is made of a highly reflective metal material (for example, an Al alloy), and the base 10 also functions as a reflector that reflects the light emitted from the chip 12. Further, in this LED 1, the chip 12 is disposed in the recess G provided in the base 10 in order to increase the light extraction efficiency from the chip 12. The concave portion G has a tapered inclined surface 10a whose opening area increases as the distance from the base surface increases. The concave portion G extends horizontally from the chip 12 with respect to the mounting surface of the chip (the base on which the chip is disposed). Light emitted in a direction parallel to the base surface) can be reflected and extracted in a direction perpendicular to the mounting surface.

  A buried groove g as a concave portion is provided on the bottom surface of the concave portion G, and the lead electrode 14 is buried in the buried groove g with an insulating film 13 interposed therebetween. The lead electrode 14 is connected to the p-side electrode (electrode opposite to the base 10) 15 of the chip 12 by, for example, a gold bonding wire 16. A transparent lens cap 18 made of resin or the like is attached to the base 10 so as to cover the concave portion G. In addition, the space | interval of the chip | tip 12 and the lens cap 18 is about 2 mm, for example.

In addition, the base 10 is provided with a hole 10 b that communicates with the recess G. The hole 10b penetrates the inside of the base 10 in a direction parallel to the main surface of the base 10, and an insulating channel pipe for allowing the chip cooling fluid F to flow through the hole 10b. 11a and 11b are inserted and fixed. These pipes 11a and 11b are connected via a heat radiating section (not shown), and the cooling fluid F is circulated in the annular flow path. That is, the fluid F is introduced into the space A surrounded by the recess G and the cap 18 through the one pipe 11a. And after cooling the chip | tip 12 here, it discharges | emits from the other pipe 11b, is cooled by the thermal radiation part, and is again introduce | transduced into the space A via the pipe 11a.
The size of the pipes 11a and 11b is, for example, Φ2. As the fluid F, any of liquid materials such as silicon oil, water, and alcohol, or gases such as nitrogen gas may be used. In the present embodiment, for example, nitrogen gas is used as the fluid F, the temperature of the nitrogen gas is 20 ° C., and the flow rate is 2 cm ³ / s.

  Further, in this embodiment, in order to protect the element 1 from the fluid F, at least the surface of the member exposed to the fluid F in the space A is covered with the protective film 17 made of a translucent inorganic insulating material. The protective film 17 is formed by depositing an insulating material after the chip 12 is mounted on the base 10.

  The protective film 17 preferably has a configuration in which the refractive index is gradually changed from the chip side to the fluid side in order to increase the extraction efficiency of the emitted light. Specifically, it is preferable that the protective film 17 is a multilayer film, and the respective insulating films constituting the protective film are arranged in descending order of refractive index from the chip side. The number of layers of this protective film can be freely determined from the viewpoint of insulation, heat dissipation, productivity, etc., but if it is a laminated film of about 3 layers, it will exhibit sufficient performance without impairing productivity. Can do. For example, in this embodiment, the protective film 17 is composed of first, second, and third layers of insulating films in order from the chip side.

As materials for these insulating films, for example, in the first insulating film 171 arranged closest to the chip 12, TiO ₂ (2.3 to 2.55), Ta ₂ O ₅ (2.1), ZnO (2 .1), ZrO ₂ (2.05), and the second insulating film 172 disposed thereon has MgO (1.74), Al ₂ O ₃ (1.63), disposed at the position farthest from the chip. In the third insulating film, MgO (1.74) or Al ₂ O ₃ (1.63) can be used. In parentheses are the refractive indexes of the respective insulating film materials.

Note that each insulating film may be formed of one kind of material, or may include some of the materials described above. Since TiO ₂ has a photocatalytic action, when TiO ₂ is used as a protective film, the cooling fluid is an inorganic material, or when the cooling fluid is an organic material, the TiO ₂ film is a fluid. It is desirable to stack one or more insulating films on the TiO ₂ film so that they do not come into contact with each other. Also, since MgO has low water resistance, when this MgO is used as a protective film, water should not be used as the cooling fluid, or when water is used as the cooling fluid, the MgO film It is desirable to stack one or more insulating films on the MgO film so as not to contact the fluid.

Thus, when the refractive index is gradually changed from the chip 12 side toward the fluid F side, each boundary surface (interface between the chip and insulating film, interface between adjacent insulating films, and between insulating film and fluid) The critical angle at which total reflection occurs is large at the interface), and the ratio of light totally reflected is small, that is, the light extraction efficiency is high.
In the present embodiment, for example, the first insulating film is Ta ₂ O ₅ , the second insulating film is Al ₂ O ₃ , and the third insulating film is SiO ₂ . In the present embodiment, the thickness of the protective film is 0.8 μm or more and 1.5 μm or less.

  The insulating films 171 to 173 can be formed by various methods such as sputtering, plasma CVD, EB deposition, etc., sol-gel, SOG (Spin On Glass), dipping, etc. However, in order to obtain a denser film, it is preferable to use a vapor deposition method.

The LED 1 described above can be manufactured by the following procedure.
First, a reflector-integrated base 10 having a hole 10b communicating with the recess G as shown in FIG. And the chip | tip 12 is mounted with the Ag paste in the recessed part G of this base 10, and wire bonding is performed (mounting process). FIG. 3B is a diagram showing a state after chip mounting.

Then, the protective film 17 is formed in such a state that the chip 12 is mounted (protective film forming step). In this protective film forming step, the protective film 17 is formed so as to cover the entire surface of the chip 12 (including the electrode 15) and the surface of the base 10 on which the chip 12 is mounted. Specifically, first, Ta ₂ O ₅ is formed as a first insulating film 171 on the surfaces of the chip 12 and the base 10 by oblique sputtering. At this time, sputtering is performed while rotating the base 10 so that the insulating film 171 can be sufficiently formed also on the inner wall surface 10a of the recess and the shadowed portion of the bonding wire 16. Next, Al ₂ O ₃ is formed by CVD as the second insulating film 172, and SiO ₂ is formed by vapor deposition as the third insulating film 173. Thus, the protective film 17 is formed on the chip surface. FIG. 3C shows a state after the protective film is formed. The thickness of each insulating film is, for example, 250 nm for the first insulating film, 500 nm for the second insulating film, and 250 nm for the third insulating film.
After the protective film 17 is formed in this way, next, the flow path pipes 11a and 11b are attached, and then the transparent lens cap 18 made of resin or the like is attached so as to cover the concave portion G. Thus, the LED 1 is manufactured.

  In the protective film forming step, it is not always necessary to form the protective film on the entire surface of the base. That is, since the protective film 17 is intended for protection from the fluid F, the protective film 17 may be formed so as to cover at least the entire surface where the chip 12 and the base 10 are exposed to the fluid F. Therefore, as long as the film forming method can selectively form the protective film 17, the protective film 17 may be formed only on the surface of the member disposed in the space A (see FIG. 1).

Thus, in this embodiment, since the outer surface of the part of the chip 12 exposed to the cooling fluid F is entirely covered with the protective film 17, a short circuit between the electrodes via the fluid F can be prevented. In particular, in this embodiment, since the protective film 17 is formed after mounting the chip, the surface of the electrode 15 of the chip 12 and the base 10 is also covered with the protective film 17, and such a short circuit can be prevented more reliably. it can.
In this embodiment, since the chip 12 and the base 10 are completely isolated from the cooling fluid F by the protective film 17, the chip 12 deteriorates due to a chemical reaction with the fluid F, or the base 10 is altered. There is no corrosion.

  Further, when the protective film 17 is arranged between the fluid F and the chip 12 in this way, a temperature change (temperature gradient) generated at the interface with the fluid F is partially absorbed by the protective film 17, so that the chip surface The temperature gradient generated in is smaller than that without the protective film. For example, it is assumed that the cooling of the fluid F causes a temperature gradient of several tens of degrees Celsius in the range of about 1 μm thickness that forms the interface with the fluid F. When there is no protective film, this directly becomes the temperature gradient of the chip surface, but since a plurality of layers having different thermal expansion coefficients are usually arranged in the thickness range of about 1 μm on the surface of the chip. Due to the difference in thermal expansion coefficient, a large strain is generated between these layers. This distortion not only changes the light emission characteristics of the chip, but also causes defects in the chip, thereby shortening the lifetime. On the other hand, in the configuration of the present embodiment, most of the temperature gradient generated in the thickness range of about 1 μm is absorbed by the protective film 17, so that the temperature gradient generated in the chip itself is reduced. Actually, in the LED of the structure of this embodiment, although there are individual differences, the half-life is improved to about 1.2 times that of the conventional one without a protective film.

Moreover, in this embodiment, since the electrode 15 of the chip 12 is covered with the protective film 17, the bonding portion between the wire 16 and the electrode 15 is fixed, so that the mechanical strength of the element is also increased. In fact, when performing face-up mounting, the reliability of wire connection is an important issue even in the conventional structure in which direct cooling with a fluid is not performed. In the structure where the load of F is applied, there is a possibility that the problem of peeling of the joint portion becomes obvious. Therefore, the configuration of the present embodiment in which the joint portion can be reinforced by the protective film 17 is also effective from such a viewpoint.
In the present embodiment, since the protective film 17 and the fluid F are made of an inorganic material, they are not photodegraded by the light emitted from the chip, which leads to further improvement in device reliability.

[Second Embodiment]
Next, a light source device according to a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same reference numerals are given to the same members or parts as those in the first embodiment, and the description thereof is partially omitted.
In the LED (light source device) 2 of the present embodiment, an LED chip 22 as a solid light source is face-down mounted (flip chip mounted) on a semiconductor material substrate 29, and the substrate 29 is disposed on a metal base 20. Is.

The chip 22 is made of, for example, an InGaN mixed crystal, and both anode and cathode electrodes are connected to wirings 251 and 252 on the semiconductor substrate 29 by solder bumps or the like. The wires 251 and 252 are connected to lead electrodes 241 and 242 formed on the base 20 by, for example, gold bonding wires 261 and 262, respectively. The chip size is, for example, 1 mm × 1 mm.
The base 20 is made of a highly reflective metal material (for example, an Al alloy), and the base 20 also functions as a reflector that reflects the light emitted from the chip 22. Further, in this LED 2, the chip 22 is disposed in the recess G provided in the base 20 in order to increase the light extraction efficiency from the chip 22. The concave portion G has a tapered inclined surface 20a whose opening area increases as the distance from the base surface increases. The concave portion G extends horizontally from the chip 22 to the mounting surface of the chip (the base on which the chip is disposed). Light emitted in a direction parallel to the base surface) can be reflected and extracted in a direction perpendicular to the mounting surface.

  On the bottom surface of the recess G, embedded grooves g1 and g2 are provided as recesses, and the lead electrodes 241 and 242 are embedded in the embedded grooves g1 and g2 via insulating films 231 and 232, respectively. . The lead electrodes 241 and 242 are connected to the electrodes 251 and 252 on the semiconductor substrate 29 by bonding wires 261 and 262, respectively. A transparent lens cap 28 made of resin or the like is attached to the base 20 so as to cover the recess G. In addition, the space | interval of the chip | tip 22 and the lens cap 28 is about 2 mm, for example.

In addition, the base 20 is provided with a hole 20 b that communicates with the recess G. The hole 20b penetrates the inside of the base 20 in a direction parallel to the main surface of the base 20, and an insulating channel pipe for allowing the chip cooling fluid F to flow through the hole 20b. 21a and 21b are inserted and fixed. These pipes 21a and 21b are connected via a heat radiating portion (not shown), and the cooling fluid F is circulated in the annular flow path. The size of the pipes 21a and 21b is, for example, Φ2. In this embodiment, the fluid F is silicon oil, the temperature of the oil is 25 ° C., and the flow rate is 0.2 cm ³ / s.

In the present embodiment, in order to protect the element 2 from the fluid F, at least the surface of the member exposed to the fluid F in the space A is covered with the protective film 27 made of a translucent inorganic insulating material. The protective film 27 has, for example, a three-layer structure of Zr ₂ O, Al ₂ O ₃ , and SiO ₂ in order from the chip side in order to increase the light extraction efficiency.
As described above, an evaporation method capable of forming a denser film is suitable for forming the protective film. However, when a slight gap is generated between the base 20 or the semiconductor substrate 29 and the chip 22 as in face-down mounting, a sufficient film cannot be formed in the gap by the vapor deposition method. Therefore, in this embodiment, a liquid coating method is suitable as a method for forming the protective film 27. However, since the coating film has a problem in terms of denseness, it is preferable that only a part of the protective film 27 is formed by a coating method and the other part is formed by a vapor deposition method.

Specifically, after the chip 22 is mounted on the base 20 and wire bonding is performed, first, Zr ₂ O is formed as a first insulating film 271 on the surfaces of the chip 22 and the base 20 by oblique sputtering. To do. At this time, sputtering is performed while rotating the base 20 so that the insulating film is uniformly formed on the surfaces of the chip 22 and the base 20. Next, Al ₂ O ₃ is formed as the second insulating film 272 by CVD. And after covering the surface of a chip | tip and a base with a precise | minute insulating film in this way, the 3rd insulating film is formed into a space between the chip | tip 22 and the base 20 by SOG method. In this coating film forming step, for example, a solution in which SiO ₂ is dissolved in an organic solvent at a concentration of about 5% is applied on the chip 22 and the electrodes 251 and 252 and baked at about 300 ° C. for about 2 hours. A quality film. Thereby, a third insulating film made of SiO ₂ is formed. The thickness of each insulating film is, for example, 250 nm for the first insulating film, 500 nm for the second insulating film, and 300 nm for the third insulating film.

  As described above, also in the present embodiment, the gradient of the temperature distribution in the chip is moderated by the protective film, and the thermal stress caused by the difference in coefficient of thermal expansion is alleviated. Also, the bonding portion between the bonding wire and the lead electrode and the bonding portion between the chip and the semiconductor substrate are fixed by the protective film, thereby preventing the bonding wire from being damaged by the flow of the fluid F and peeling of the chip from the semiconductor substrate. Is done. Furthermore, the chip and the like can be prevented from being deteriorated by isolating the chip and the base from the fluid by the protective film. Therefore, the reliability of the chip is improved and high brightness can be achieved.

[Third Embodiment]
Next, a light source device according to a third embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same reference numerals are given to the same members or parts as those in the first and second embodiments, and the description thereof is partially omitted.
The LED (light source device) 3 of the present embodiment is obtained by mounting an LED chip 32 as a solid light source face-down on a metal base 30.

The chip 32 is made of, for example, an InGaN mixed crystal, and both anode and cathode electrodes thereof are connected to the lead electrodes 341 and 342 of the base 30 by solder bumps or the like. The chip size is, for example, 1 mm × 1 mm.
The base 30 is made of a highly reflective metal material (for example, an Al alloy), and the base 30 also functions as a reflector that reflects the light emitted from the chip 32. Further, in this LED 3, the chip 32 is disposed in the recess G provided in the base 30 in order to increase the light extraction efficiency from the chip 32. The concave portion G has a tapered inclined surface 30a whose opening area increases as the distance from the base surface increases. The concave portion G extends horizontally from the chip 32 to the mounting surface of the chip (the base on which the chip is disposed). Light emitted in a direction parallel to the base surface) can be reflected and extracted in a direction perpendicular to the mounting surface.

  Embedded grooves g1 and g2 as concave portions are provided on the bottom surface of the concave portion G, and lead electrodes 341 and 342 are embedded in the embedded grooves g1 and g2 via insulating films 331 and 332, respectively. . The lead electrodes 341 and 342 are respectively connected to the anode electrode and the cathode electrode of the chip 32 by solder bumps or the like. A transparent lens cap 38 made of resin or the like is attached to the base 30 so as to cover the recess G. The distance between the chip 32 and the lens cap 38 is, for example, about 2 mm.

In addition, the base 30 is provided with a hole 30 b that communicates with the recess G. The hole 30b penetrates the inside of the base 30 in a direction parallel to the main surface of the base 30, and an insulating channel pipe for allowing the chip cooling fluid F to flow through the hole 30b. 31a and 31b are inserted and fixed. These pipes 31a and 31b are connected via a heat radiating section (not shown), and the cooling fluid F is circulated in the annular flow path. The size of the pipes 31a and 31b is, for example, Φ2. In this embodiment, the fluid F is pure water, the temperature of the pure water is 25 ° C., and the flow rate is 0.2 cm ³ / s.

In the present embodiment, in order to protect the element 3 from the fluid F, at least the surface of the member exposed to the fluid F in the space A is covered with a protective film 37 made of a translucent inorganic insulating material. The protective film 37 has a three-layer structure of Zr ₂ O, Al ₂ O ₃ , and SiO ₂ in order from the chip side, for example, in order to increase the light extraction efficiency. The protective film 37 can be formed by the same procedure as that of the second embodiment. That is, Zr ₂ O which is the first insulating film disposed on the chip side and Al ₂ O ₃ which is the second insulating film are formed by vapor deposition, and are disposed at the position farthest from the chip 32. SiO ₂ as the third insulating film is formed by a liquid coating method. The step of forming the protective film 37 is performed after chip mounting.

  As described above, also in the present embodiment, the gradient of the temperature distribution in the chip is moderated by the protective film, and the thermal stress caused by the difference in coefficient of thermal expansion is alleviated. Further, the chip and the base can be prevented from being deteriorated by isolating the chip and the base from the fluid by the protective film. Therefore, the reliability of the chip is improved and high brightness can be achieved.

[Projection type display device]
Next, the projection type display device of the present invention will be described with reference to FIG.
The projection display device according to the present embodiment is a three-plate projection color liquid crystal display device having a transmissive liquid crystal light valve for each color of R (red), G (green), and B (blue). FIG. 6 is a schematic configuration diagram showing this projection type liquid crystal display device, in which reference numerals 100R, 100G, and 100B are illumination devices, 111 and 112 are fly-eye lenses, and 200R, 200G, and 200B are liquid crystal light valves (light Modulator), 300 is a cross dichroic prism (color synthesis means), and 400 is a projection lens.

  Light valves 200R, 200G, and 200B as light modulators are arranged to face each other on the three light incident surfaces of the dichroic cross prism 300 as the color synthesizing means, and the back side of each light valve (with the cross dichroic prism 300 and On the opposite side, illumination devices 100R, 100G, and 100B capable of emitting color lights of R (red), G (green), and B (blue) are arranged. These illuminating devices are formed by arranging a plurality of the above-described light source devices on a substrate.

  Between the lighting devices 100R, 100G, and 100B and the corresponding light valves 200R, 200G, and 200B, as the illuminance uniformizing means 110 for uniformizing the illuminance distribution of the illumination light on the light valve, the lighting device side To the first fly-eye lens 111 and the second fly-eye lens 112 are sequentially installed. The first fly-eye lens 111 forms a plurality of secondary light source images, and the second fly-eye lens 112 functions as a superimposing lens that superimposes them at the light valve installation position, which is the illuminated area. Thereby, the light emitted from the illumination device can be irradiated to the entire surface of the light valve at a uniform density regardless of the density distribution of the light.

The dichroic cross prism 300 has a structure in which four right-angle prisms are bonded together, and light reflection films (not shown) made of a dielectric multilayer film are formed in a cross shape on the bonded surfaces 300a and 300b. Specifically, the reflection surface that reflects the red image light formed by the light modulation device 200R and transmits the green and blue image light formed by the light modulation devices 200G and 200B to the bonding surface 300a, respectively. A light reflection that reflects the blue image light formed by the light modulation device 200B and transmits the red and green image light formed by the light modulation devices 200R and 200G, respectively, is provided on the bonding surface 300b. A membrane is provided. The image light of each color guided by these light reflecting films is projected onto the screen 500 by the projection lens 40.
Thus, since the projection type display apparatus of this embodiment is equipped with the above-mentioned light source device as an illuminating device, a bright and reliable projection type display apparatus can be implement | achieved.

In addition, this invention is not limited to the above-mentioned embodiment, It can implement in various deformation | transformation in the range which does not deviate from the meaning of this invention.
For example, in the above-described LEDs 1 to 3, the protective film has been described as having a three-layer structure, but it may be a multilayer film of two layers or four or more layers.
Moreover, although the said embodiment demonstrated the example which used the light source device as the semiconductor light emitting element, this light source device may be an organic EL element.
In addition, the configuration of the light source device shown in the above embodiment is merely an example, and other configurations can be employed. In any case, the light source device may include a solid light source and a cooling mechanism that cools the solid light source with a cooling fluid, and all the exposed surface of the solid light source with respect to the fluid may be covered with a protective film.

1 is a cross-sectional view illustrating a schematic configuration of a light source device according to a first embodiment of the present invention. The expanded sectional view which shows the principal part structure of the light source device. Process drawing for demonstrating the manufacturing method of a light source device same as the above. Sectional drawing which shows schematic structure of the light source device which concerns on 2nd Embodiment of this invention. Sectional drawing which shows schematic structure of the light source device which concerns on 3rd Embodiment of this invention. The figure which shows schematic structure of the projection type display apparatus of this invention.

Explanation of symbols

1, 2, 3 ... LED (light source device) 10, 20, 30 ... base, 12, 22, 32 ... LED chip (solid light source), 15, 251, 252 ... electrode, 17, 27, 37 ... protective film , 100R, 100G, 100B ... illumination device, 200R, 200G, 200B ... liquid crystal light valve (light modulation device), 400 ... projection lens, 171 ... first insulating film, 172 ... second insulating film, 173: Third insulating film, F: Cooling fluid

Claims (15)

A light source device comprising a solid light source and a mechanism for directly cooling the solid light source with a cooling fluid,
A light source device, wherein a protective film made of a translucent insulating material is provided on an outer surface including the electrode of the solid light source so as to cover at least the exposed surface of the solid light source with respect to the fluid.   The light source device according to claim 1, wherein the protective film is provided so as to cover an exposed surface of the base on which the solid light source is mounted with respect to the fluid.   The light source device according to claim 1, wherein the protective film is made of an inorganic material.   The said protective film consists of a laminated film of the some insulating film from which a refractive index mutually differs, These insulating films were laminated | stacked in order with a high refractive index with respect to the said solid light source. The light source device according to any one of the above. The protective film has a structure in which first, second, and third layers of insulating films are laminated in order from the solid light source side, and the first insulating film is made of TiO ₂ , Ta ₂ O ₅ , ZnO, The ZrO _{2 material} is included, the second insulating film includes MgO or Al ₂ O ₃ , and the third insulating film includes SiO ₂ or MgF _2. 4. The light source device according to 4.   The light source device according to claim 1, wherein the cooling fluid is made of an inorganic material.   The light source device according to claim 1, wherein the cooling fluid is made of a liquid material.   The light source device according to claim 1, wherein the protective film has a thickness of 0.8 μm or more and 1.5 μm or less. A method of manufacturing a light source device comprising a solid light source and a mechanism for directly cooling the solid light source with a cooling fluid,
A mounting process for mounting a solid light source on a base;
And a protective film forming step of forming a translucent protective film made of an insulating material on the outer surface including the electrode of the mounted solid light source so that at least the exposed surface of the solid light source with respect to the fluid is covered. A method of manufacturing a light source device, characterized in that   10. The method of manufacturing a light source device according to claim 9, wherein in the protective film forming step, a protective film positioned at least at an interface with the solid light source is formed by a vapor deposition method.   11. The method of manufacturing a light source device according to claim 10, wherein in the protective film forming step, the protective film is formed by a rotational oblique vapor deposition method.   10. The mounting step is a step of mounting the solid light source face-down on a base, and in the protective film forming step, at least a part of the protective film is formed by a liquid coating method. Or the manufacturing method of the light source device of 10.   The protective film forming step is a step of forming the protective film as a laminated film of a plurality of insulating films. In this protective film forming step, an insulating film disposed closest to the solid light source is formed by vapor deposition, and a solid light source The method of manufacturing a light source device according to claim 12, wherein the insulating film disposed at a position farthest from the substrate is formed by a liquid coating method.   The method of manufacturing a light source device according to claim 12 or 13, wherein the thickness of the protective film formed by the liquid coating method is 0.3 µm or less. A light source device according to any one of claims 1 to 8, a light modulation device that modulates light emitted from the light source device, and a projection lens that projects the modulated light. Projection type display device.

Images