JP2012222033A - Light-emitting diode manufacturing method and cutting method and light-emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting diode manufacturing method and cutting method which use a metal substrate having excellent chemical resistance and which include a step of achieving the purposes for reducing debris generated when the metal substrate is cut by laser and determining the position of laser irradiation suitable for the metal substrate at the same time, and a light-emitting diode itself.SOLUTION: A light-emitting diode manufacturing method according to the present invention includes: a step of fabricating a wafer having a metal substrate consisting of plural metal plates and metal protective films covering at least the top and bottom faces of the plural metal plates and a compound semiconductor layer; a step of removing a portion on a planned cutting line of the compound semiconductor layer by etching; a step of removing, by etching, at least part of at least one of the metal protective films on a side thereof opposite to the one on which side the compound semiconductor layer is formed, thereby forming a positioning mark; and a step of irradiating, based on the positioning mark, a laser on a side of films opposite to the one on which side the compound semiconductor layer is formed, thereby cutting the metal substrate.

Description

  The present invention relates to a light emitting diode manufacturing method, a cutting method, and a light emitting diode, and more particularly to a light emitting diode manufacturing method, a cutting method, and a light emitting diode using a metal substrate as a substrate.

Conventionally, a light _- emitting layer made of aluminum gallium arsenide (compositional formula Al _X Ga _1-X As; 0 ≦ X ≦ 1) is provided as a high-power light-emitting diode (an abbreviation: LED) that emits red and infrared light. Compound semiconductor LEDs are known. On the other hand, as a high-intensity light-emitting diode (English abbreviation: LED) that emits red, orange, yellow, or yellow-green visible light, aluminum phosphide, gallium, indium (composition formula (Al _X Ga _1-X ) _Y In _1-Y A compound semiconductor LED having a light emitting layer composed of P; 0 ≦ X ≦ 1, 0 <Y ≦ 1) is known. In general, a substrate material such as gallium arsenide (GaAs) that is optically opaque to light emitted from the light emitting layer and that is not mechanically strong has been used as a substrate for these LEDs.

  Therefore, recently, in order to obtain a brighter LED, and to further improve the mechanical strength and heat dissipation of the element, the substrate material opaque to the emitted light is removed. Subsequently, a technique for constructing a junction-type LED by re-joining a support layer (substrate) made of a material that transmits or reflects emitted light and is excellent in mechanical strength and heat dissipation is disclosed (for example, a patent). Reference 1-7).

With the development of substrate bonding technology, the degree of freedom of a substrate that can be applied as a support layer has increased, and the application of a metal substrate having great advantages such as cost, mechanical strength, and heat dissipation has been proposed.
In particular, a high-power light-emitting diode that needs to emit light at a high current has a larger amount of heat generation than a conventional one, and ensuring heat dissipation is a problem. Since the metal substrate can efficiently release the heat generated from the light emitting part (compound semiconductor layer) to the outside of the light emitting diode, bonding the metal substrate to the compound semiconductor layer increases the output of the light emitting diode and increases the lifetime. It is useful for conversion.

  Light emitting diodes using a metal substrate are disclosed in, for example, Patent Document 8 and Patent Document 9.

A wafer obtained by bonding a metal substrate to a compound semiconductor layer having a light emitting layer is formed into a chip by blade dicing, laser dicing, or the like.
Here, blade dicing is performed by pressing a disk-shaped cutting blade rotating at high speed on a substrate.
Laser dicing is performed by irradiating a substrate with a laser, absorbing the laser energy, and melting and evaporating (ablating) the cut portion with heat energy generated.

JP 2001-339100 A JP-A-6-302857 JP 2002-246640 A Japanese Patent No. 2588849 JP 2001-57441 A JP 2007-81010 A JP 2006-32952 A JP-A-2005-236303 JP 2006-13499 A

  However, the metal substrate has a problem that the quality of the metal substrate is deteriorated due to reaction, corrosion, or the like with a chemical used in the manufacturing process as compared with a semiconductor substrate or a ceramic substrate. Specifically, there are problems that dissolution, discoloration, and corrosion occur in the treatment of alkali and acid, resulting in poor characteristics and a decrease in yield. In particular, in order to remove the gallium arsenide substrate on which the semiconductor layer is grown, a process of immersing in alkali or acid for a long time to dissolve all the gallium arsenide substrate is common, but the metal substrate can withstand this long chemical treatment. There was a problem that it was not possible.

  Further, in the cutting of the metal substrate by blade dicing, there is a problem that the cutting is not easy because the blade is likely to be clogged. There is also a problem that chipping or cracking occurs on the cut surface, which affects the circuit area. Furthermore, since the width of the cutting blade is large and there is chipping, it is necessary to increase the width of the line to be cut, and there is a problem that the ratio of the area that can be effectively used as a circuit region is reduced.

On the other hand, in the cutting of a metal substrate by laser dicing, there is no established method for positioning (alignment) of laser irradiation, and various trials and errors have been made, and debris generated at the time of cutting also becomes a problem.
Here, debris is a by-product generated by irradiation with a laser beam, and is obtained by adhering a melted material or scattered material of an irradiated material around the cut portion (material surface or cut surface). .

  Debris not only causes the appearance of light emitting diodes to deteriorate, but if debris attaches to the front side, it causes wire bonding failure, and if it attaches to the back side, it causes die bonding failure. .

  In addition, when such debris is frequently generated on the light emitting portion side, the reliability of the light emitting diode may be deteriorated, for example, a short circuit occurs due to contact with the side surface of the compound semiconductor layer constituting the light emitting portion.

  In order to avoid such a problem, it is conceivable to increase the margin of the cut portion, but in this case, the number of light emitting diodes that can be manufactured from one wafer is reduced.

  The present invention has been made in view of the above circumstances, and a light-emitting diode having improved yield and stable characteristics by using a metal substrate having a new structure excellent in chemical resistance that can withstand chemical treatment in the substrate removal process. And a method for manufacturing a light-emitting diode including a step of simultaneously reducing the debris generated when cutting a metal substrate by laser dicing and positioning the laser irradiation suitable for the metal substrate having the new structure And it aims at providing a light emitting diode.

The present invention provides the following means in order to solve the above problems.
(1) In a method for manufacturing a chip-shaped light emitting diode by irradiating a laser on a wafer,
A metal substrate comprising a plurality of metal plates and a metal protective film comprising one or more films covering at least upper and lower surfaces of the plurality of metal plates; and a compound semiconductor layer including a light emitting layer formed on the metal substrate; And a step of removing a portion of the compound semiconductor layer on the planned cutting line by etching, and a surface of the metal protective film opposite to the surface provided with the compound semiconductor layer. Removing at least a portion of at least one film by etching to form a positioning mark; and, based on the positioning mark, irradiating a surface opposite to the surface including the compound semiconductor layer by irradiating a laser And a step of cutting the metal substrate.
Here, the “scheduled cutting line” indicates a position to be cut on the wafer, and a line formed by actually performing some processing on the substrate or the like is also subjected to actual processing. Virtual lines that are not included are also included.
Further, the “part on the planned cutting line” means a part including the “scheduled cutting line” in plan view.
(2) The plurality of metal plates include a metal plate made of a material having a thermal expansion coefficient larger than that of the compound semiconductor layer and a metal made of a material having a thermal expansion coefficient smaller than that of the compound semiconductor layer. A method for producing a light-emitting diode according to item (1), comprising a plate.
(3) The material according to the preceding item, wherein the material having a thermal expansion coefficient larger than that of the compound semiconductor layer is made of aluminum, copper, silver, gold, nickel, titanium, tin, or an alloy thereof. The manufacturing method of the light emitting diode in any one of 1) or (2).
(4) Any of (1) to (3) above, wherein the material having a thermal expansion coefficient smaller than that of the compound semiconductor layer is any one of molybdenum, tungsten, chromium, and alloys thereof. A method for producing a light-emitting diode according to claim 1.
(5) The method for manufacturing a light-emitting diode according to any one of (1) to (4), wherein the plurality of metal plates include three metal plates.
(6) The method for manufacturing a light-emitting diode according to (5) above, wherein, of the three metal plates, two metal plates sandwiching one metal plate are made of the same metal material.
(7) The method for manufacturing a light-emitting diode according to (6), wherein the one metal plate is made of molybdenum, and the two metal plates are made of copper.
(8) The metal protective film according to any one of (1) to (7), wherein the metal protective film is made of any one of aluminum, silver, gold, nickel, titanium, tin, or an alloy thereof. Manufacturing method of light emitting diode.
(9) The light emitting diode manufacturing method according to any one of (1) to (8), wherein the light emitting layer includes an AlGaInP layer or an AlGaInAs layer.
(10) The method for producing a light-emitting diode according to any one of (1) to (9), wherein a reflective structure is provided between the compound semiconductor layer and the metal substrate.
(11) A metal substrate comprising a plurality of metal plates and a metal protective film comprising one or more films covering at least the upper and lower surfaces of the plurality of metal plates, and a compound semiconductor layer formed on the metal substrate In the method of irradiating a wafer with a laser to cut into chip-shaped light emitting diodes, a step of removing a portion of the compound semiconductor layer on a cutting scheduled line by etching, and the compound semiconductor layer of the metal protective film is removed. Removing at least a part of at least one film on the surface opposite to the provided surface by etching to form a positioning mark; and on the basis of the positioning mark, opposite to the surface having the compound semiconductor layer Cutting the metal substrate by irradiating the side surface with a laser.
(12) A light-emitting diode manufactured by the method for manufacturing a light-emitting diode according to any one of (1) to (10).

  According to the method for manufacturing a light emitting diode according to the present invention, a configuration using a metal substrate composed of a plurality of metal plates and a metal protective film composed of one or more films covering at least the upper and lower surfaces of the plurality of metal plates is adopted. Therefore, it is possible to manufacture a light emitting diode having high chemical resistance and no deterioration of the metal substrate due to alkali and acid treatment. By adopting a configuration in which the metal protective film covers the side surfaces of the plurality of metal plates, the effect can be further enhanced.

  According to the method for manufacturing a light emitting diode according to the present invention, the step of removing the portion of the compound semiconductor layer on the planned cutting line by etching, and the surface of the metal protective film opposite to the surface provided with the compound semiconductor layer Removing at least a part of at least one of the films by etching to form a positioning mark, and irradiating a laser on a surface opposite to the surface having the compound semiconductor layer based on the positioning mark to form a metal A step of cutting the substrate, and the laser irradiation surface is a surface opposite to the surface provided with the compound semiconductor layer, so that the position of the metal substrate where laser cutting is started is far from the compound semiconductor layer. As a result, it becomes difficult for debris to reach the compound semiconductor layer, and it is possible to prevent a short circuit and improve the yield. In addition, since a part of the metal substrate on the laser irradiation side (a part of the metal protective film) is removed in advance by etching, the amount of the metal substrate to be laser cut is reduced and the amount of debris generated is reduced. Can do.

  According to the method of manufacturing a light emitting diode according to the present invention, the plurality of metal plates are smaller than the thermal expansion coefficient of the metal plate made of a material having a thermal expansion coefficient larger than that of the compound semiconductor layer and the compound semiconductor layer. By adopting a configuration that includes a metal plate made of a material having a thermal expansion coefficient, the thermal expansion coefficient of the entire metal substrate (the rate at which the length and volume of the metal substrate that actually appears with respect to temperature rise) expands. Since it becomes close to the coefficient of thermal expansion of the compound semiconductor layer, the difference between the amount of thermal expansion of the metal substrate and the amount of thermal expansion of the compound semiconductor layer when bonding the compound semiconductor layer and the metal substrate is reduced. The interfacial stress generated between the semiconductor layer and the metal substrate is reduced. As a result, of the interfacial stress existing on the compound semiconductor layer side and the opposite side of the compound semiconductor layer of the metal substrate, the laser During disconnection, one interface stress distortion of the metal substrate by being opened previously is reduced.

  According to the method for manufacturing a light emitting diode according to the present invention, by adopting a configuration in which the plurality of metal plates are made of three metal plates, functions desired for the metal substrate, such as mechanical strength, ease of cutting, heat dissipation, etc. It is possible to manufacture a light emitting diode having a metal substrate in which each substrate is held separately. In this case, the metal substrate has a function that cannot be possessed by a single metal plate. For example, the outer two metal plates, such as Cu / Mo / Cu, are made of Cu, which is a material with high cutting easiness, and Mo is a material with high mechanical strength in the middle metal plate sandwiched between them. By comprising, it can be set as a metal substrate with high mechanical strength and easy cutting.

  According to the cutting method according to the present invention, since a configuration using a metal substrate composed of a plurality of metal plates and a metal protective film composed of one or more films covering at least the upper and lower surfaces of the plurality of metal plates is employed. A light-emitting diode having high chemical resistance and no deterioration of the metal substrate due to alkali or acid treatment can be produced. By adopting a configuration in which the metal protective film covers the side surfaces of the plurality of metal plates, the effect can be further enhanced.

  According to the cutting method of the present invention, at least one of the step of removing the portion of the compound semiconductor layer on the planned cutting line by etching and the surface of the metal protective film opposite to the surface having the compound semiconductor layer is provided. A step of forming a positioning mark by removing at least a part of the two films by etching, and irradiating a laser on a surface opposite to the surface having the compound semiconductor layer based on the positioning mark in plan view. The step of cutting the metal substrate is adopted, and the laser irradiation surface is the surface opposite to the surface provided with the compound semiconductor layer, so the position of the metal substrate where laser cutting is started is the compound semiconductor layer As a result, it is difficult for debris to reach the compound semiconductor layer as a result of being far away from the substrate, and it is possible to prevent a short circuit and improve the yield. In addition, since a part of the metal substrate on the laser irradiation side (a part of the metal protective film) is removed in advance by etching, the amount of the metal substrate to be laser cut is reduced and the amount of debris generated is reduced. Can do.

It is sectional drawing which shows an example of the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing process of the metal substrate used for the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing method of the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing method of the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing method of the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing method of the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing method of the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing method of the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing method of the light emitting diode which is embodiment of this invention. It is process sectional drawing which shows an example of the manufacturing method of the light emitting diode which is embodiment of this invention. It is sectional drawing which shows an example of the light emitting diode lamp provided with the light emitting diode which is embodiment of this invention.

    Hereinafter, a light emitting diode manufacturing method, a cutting method, and a light emitting diode according to an embodiment to which the present invention is applied will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent. Moreover, the specific conditions such as materials and dimensions are merely examples. Moreover, the same code | symbol is attached | subjected to the same member and description is abbreviate | omitted or simplified. Further, the same members are appropriately given the same reference numerals or omitted, and the description thereof is omitted or simplified.

(First embodiment)
[Light emitting diode]
FIG. 1 is a diagram illustrating an example of a light emitting diode according to an embodiment of the present invention.
As shown in FIG. 1, a light emitting diode (LED) 100 according to an embodiment of the present invention includes a plurality of metal plates 21A, 22, 21B (reference numeral 1A indicates a plurality of metal plates 21A, 22, 21B) and a plurality of metal plates 21A, 22, 21B. A metal substrate 1 comprising a metal protective film 1B (1Ba, 1Bb) comprising one or a plurality of films covering at least the upper surface 1Aa and the lower surface 1Ab of the metal plate, and a light emitting layer 2 formed on the metal substrate 1 In the light emitting diode 100 including the compound semiconductor layer 3, the side surface 1Aaa of the metal substrate 1 is a laser cut surface, and the byproduct (debris) by the laser irradiation is the side surface 1Aaa (of the metal plate 21A) of the metal substrate 1. It is attached only to the side surface 21Aa, the side surface 22a of the metal plate 22, and the side surface (reference numeral omitted) of the metal protective film.

<Compound semiconductor layer>
The compound semiconductor layer 3 is a stacked structure of compound semiconductors including the light emitting layer 2 and is an epitaxial stacked structure formed by stacking a plurality of epitaxially grown layers.
As the compound semiconductor layer 3, for example, an AlGaInP layer or an AlGaInAs layer that has high light emission efficiency and has established a substrate bonding technique can be used. AlGaInP layer is a layer consisting of the general formula _{(Al X Ga 1-X)} Y In 1-Y P (0 ≦ X ≦ 1,0 <Y ≦ 1) material represented by. This composition is determined according to the emission wavelength of the light emitting diode. Similarly, in the case of the AlGaInAs layer used when manufacturing red and infrared light emitting diodes, the composition of the constituent materials is determined according to the light emission wavelength of the light emitting diodes. Also included are AlGaAs, GaAs, InGaAs and the like.
The compound semiconductor layer 3 is a compound semiconductor of either n-type or p-type conductivity, and a pn junction is formed inside. The polarity of the surface of the compound semiconductor layer 3 may be either p-type or n-type.

  As shown in FIG. 1, the compound semiconductor layer 3 includes, for example, a contact layer 12c, a cladding layer 10a, a light emitting layer 2, a cladding layer 10b, and a GaP layer 13.

The contact layer 12c is a layer for reducing the contact resistance of the ohmic electrode, and is made of, for example, Si-doped n-type GaAs, having a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ and a layer thickness of 0.1. 05 μm.

The clad layer 10a is made of, for example, Si-doped n-type Al _0.5 In _0.5 P, has a carrier concentration of 3 × 10 ¹⁸ cm ⁻³ , and a layer thickness of 0.5 μm.

The light emitting layer 2 may be a known light emitting layer, but preferably includes an AlGaInP layer or an AlGaInAs layer. For example, an undoped (Al _0.2 Ga _0.8 ) _0.5 In _0.5 P / ( It consists of a laminated structure of 10 pairs of Al _0.7 Ga _0.3 ) _0.5 In _0.5 P, and the layer thickness is 0.2 μm.
The light emitting layer 2 has a structure such as a double hetero structure (Double Hetero: DH), a single quantum well structure (Single Quantum Well: SQW), or a multiple quantum well structure (Multi Quantum Well: MQW). Here, the double heterostructure is a structure in which carriers responsible for radiative recombination can be confined. The quantum well structure has a well layer and two barrier layers sandwiching the well layer. The SQW has one well layer and the MQW has two or more well layers. As a method for forming the compound semiconductor layer 3, an MOCVD method or the like can be used.
In order to obtain light emission excellent in monochromaticity from the light emitting layer 2, it is preferable to use an MQW structure as the light emitting layer 2.

The clad layer 10b is made of, for example, p-type Al _0.5 In _0.5 P doped with Mg, has a carrier concentration of 8 × 10 ¹⁷ cm ⁻³ , and a layer thickness of 0.5 μm.

The GaP layer 13 is, for example, a p-type GaP layer doped with Mg, and has a carrier concentration of 5 × 10 ¹⁸ cm ⁻³ and a layer thickness of 2 μm.

  The configuration of the compound semiconductor layer 3 is not limited to the structure described above. For example, a current diffusion layer for planarly diffusing the element driving current in the entire compound semiconductor layer 3 or the element driving current flowing therethrough. A current blocking layer or a current confinement layer for limiting the region may be provided.

<First electrode, second electrode>
Each of the first electrode 6 and the second electrode 8 is an ohmic electrode, and their shape and arrangement are not particularly limited as long as the current is uniformly diffused in the compound semiconductor layer 3. For example, a circular or rectangular electrode can be used when viewed from above, and the electrodes can be arranged as a single electrode or a plurality of electrodes can be arranged in a grid.

As the material of the first electrode 6, when an n-type compound semiconductor is used as the contact layer 12c, for example, AuGe, AuGeNi, AuSi or the like can be used, and a p-type compound semiconductor is used as the contact layer 12c. When used, for example, AuBe, AuZn, or the like can be used.
Further, Au or the like can be further laminated thereon to prevent oxidation and improve bonding characteristics.

  As the material of the second electrode 8, when an n-type compound semiconductor is used as the GaP layer 13, for example, AuGe, AuGeNi, AuSi or the like can be used, and a p-type compound semiconductor is used as the GaP layer 13. When used, for example, AuBe, AuZn, or the like can be used.

<Reflection structure>
As shown in FIG. 1, the reflective structure 4 is formed on the surface 3 b of the compound semiconductor layer 3 on the reflective structure 4 side so as to cover the second electrode 8. The reflective structure 4 is formed by laminating a metal film 15 and a transparent conductive film 14.

  The metal film 15 is made of a metal such as copper, silver, gold, or aluminum, or an alloy thereof. These materials have high light reflectivity, and the light reflectivity from the reflective structure 4 can be 90% or more. By forming the metal film 15, the light from the light emitting layer 2 is reflected by the metal film 15 in the front direction f, and the light extraction efficiency in the front direction f can be improved. Thereby, the brightness of the light emitting diode can be further increased.

The metal film 15 preferably has a laminated structure made of Ag, a Ni / Ti barrier layer, and an Au-based eutectic metal (connecting metal) from the transparent conductive film 14 side.
The connecting metal formed on the surface 15b of the metal film 15 opposite to the compound semiconductor layer 3 is a metal having a low electrical resistance and melting at a low temperature. By using the connecting metal, the metal substrate can be connected without applying thermal stress to the compound semiconductor layer 3.
As the connection metal, an Au-based eutectic metal that is chemically stable and has a low melting point is used. Examples of the Au-based eutectic metal include a eutectic composition (Au-based eutectic metal) of an alloy such as AuSn, AuGe, and AuSi.
Further, it is preferable to add a metal such as titanium, chromium, or tungsten to the connection metal. Thereby, metals such as titanium, chromium, and tungsten can function as barrier metals, and impurities contained in the metal substrate can be prevented from diffusing to the metal film 15 side and reacting.

The transparent conductive film 14 is composed of an ITO film, an IZO film, or the like. Note that the reflective structure 4 may be composed of only the metal film 15.
Further, instead of or together with the transparent conductive film 14, a so-called cold mirror using a difference in refractive index of a transparent material, for example, a multilayer film of titanium oxide film, silicon oxide film, white alumina, AlN May be combined with the metal film 15. When a nonconductive transparent film such as a SiO ₂ film, a SiN film, a TiO ₂ film, or a TiN film is used, a part of the metal film may be disposed so as to penetrate a part of the nonconductive transparent film.

<Metal substrate>
The metal substrate 1 includes a plurality of metal plates 1A and a metal protective film 1B made of one or more films covering at least the upper surface 1Aa and the lower surface 1Ab of the plurality of metal plates. The metal protective film 1B preferably covers the side surface of the metal plate.

A bonding surface 1a of the metal substrate 1 is bonded to a surface 15b on the opposite side of the compound semiconductor layer 3 of the metal film 15 constituting the reflective structure 4.
The thickness of the metal substrate 1 is preferably 50 μm or more and 150 μm or less.
When the thickness of the metal substrate 1 is thicker than 150 μm, the manufacturing cost of the light emitting diode increases, which is not preferable. Further, when the thickness of the metal substrate 1 is less than 50 μm, cracking, bending, warping, etc. easily occur during handling, which may reduce the manufacturing yield.

As the configuration of the plurality of metal plates, two types of metal plates, that is, a structure in which the first metal plate 21 and the second metal plate 22 are alternately laminated are preferable.
The total number of the first metal plate 21 and the second metal plate 22 per metal substrate is preferably 3 to 9, more preferably 3 to 5.
When the first metal plate 21 and the second metal plate 22 are combined to form two layers, the thermal expansion in the thickness direction becomes unbalanced, and the warp of the metal substrate 1 occurs. Conversely, when the total number of the first metal plate 21 and the second metal plate 22 is more than nine layers, the thicknesses of the first metal plate 21 and the second metal plate 22 are set to be different from each other. It is necessary to make it thinner. It is difficult to produce a single-layer substrate made of the first metal plate 21 or the second metal plate 22 with a thin layer thickness. The thickness of each layer is non-uniform, and the characteristics of the light-emitting diode are improved. There is a risk of dispersal. Furthermore, since it is difficult to manufacture the single-layer substrate, the manufacturing cost of the light emitting diode may be deteriorated.

More preferably, the number of the first metal plate 21 and the second metal plate 22 is an odd number in total.
In particular, it is preferable that the two metal plates sandwiching one metal plate are made of the same metal material. In this case, it is possible to remove a portion corresponding to the line to be cut by wet etching using the same etchant between the two metal plates sandwiched.

<Metal protective film>
The metal protective film 1B is composed of one or a plurality of films.
These films are preferably made of any of aluminum, silver, gold, nickel, titanium, tin or alloys thereof.
The metal protective film 1B is most preferably composed of a laminated structure in which nickel having good adhesion and gold having excellent chemical resistance are combined.
The thickness of the metal protective film is not particularly limited, but in the range of durability and cost, 0.2 to 5 μm, preferably 0.5 to 3 μm is an appropriate range. The thickness of expensive gold is desirably 2 μm or less.

The plurality of metal plates include a metal plate made of a material having a thermal expansion coefficient larger than that of the compound semiconductor layer and a metal plate made of a material having a thermal expansion coefficient smaller than that of the compound semiconductor layer. preferable.
The material having a thermal expansion coefficient larger than that of the compound semiconductor layer is preferably made of any of aluminum, copper, silver, gold, nickel, titanium, tin, and alloys thereof.
Moreover, it is preferable that the material which has a thermal expansion coefficient smaller than the thermal expansion coefficient of a compound semiconductor layer consists of molybdenum, tungsten, chromium, or these alloys.

<First metal plate>
The first metal plate 21 (21A, 21B) is made of a material having a coefficient of thermal expansion larger than that of the compound semiconductor layer 3 at least when a material having a smaller coefficient of thermal expansion than that of the compound semiconductor layer 3 is used as the second metal plate. It is preferable. By adopting this configuration, the thermal expansion coefficient of the entire metal substrate is close to the thermal expansion coefficient of the compound semiconductor layer, thus suppressing warpage and cracking of the metal substrate when joining the compound semiconductor layer and the metal substrate. This is because the manufacturing yield of light emitting diodes can be improved. Therefore, when a material having a larger thermal expansion coefficient than the compound semiconductor layer 3 is used as the second metal plate, the first metal plate 21 (21A, 21B) is made of at least a material having a smaller thermal expansion coefficient than the compound semiconductor layer 3. It is preferable to become.

Examples of the first metal plate 21 include silver (thermal expansion coefficient = 18.9 ppm / K), copper (thermal expansion coefficient = 16.5 ppm / K), gold (thermal expansion coefficient = 14.2 ppm / K), Aluminum (thermal expansion coefficient = 23.1 ppm / K), nickel (thermal expansion coefficient = 13.4 ppm / K), alloys thereof, and the like are preferably used.
The thickness of the first metal plate 21 is preferably 5 μm or more and 50 μm or less, and more preferably 5 μm or more and 20 μm or less.
The thickness of the first metal plate 21 and the thickness of the second metal plate 21 may be different. Furthermore, when the metal substrate 1 is formed of a plurality of first metal plates 21 and second metal plates 22, the thicknesses of the respective layers may be different from each other.

It is preferable to form a bonding auxiliary film that stabilizes electrical contact or a eutectic metal for die bonding on the bonding surface 1 a and the opposite surface 1 b of the metal substrate 1.
When an Au-based eutectic metal is used as a connection metal for the metal film 15 of the reflective structure, it is preferable to form a Ni / Au film on the bonding surface 1a of the metal substrate 1 from the metal substrate 1 side. The Ni film and Au film can be formed by plating.
Thereby, a joining process can be performed simply. As the auxiliary bonding film, Au, AuSn, or the like can be used.

  In addition, the method of joining the metal substrate 1 to the compound semiconductor layer 3 is not restricted to the method described above, For example, well-known techniques, such as a diffusion joining, an adhesive agent, and a normal temperature joining method, can also be applied.

The total thickness of the first metal plate 21 is preferably 5% to 50%, more preferably 10% to 30%, and more preferably 15% to 25% of the thickness of the metal substrate 1. More preferably, it is as follows. When the total thickness of the first metal plate 21 is less than 5% of the thickness of the metal substrate 1, the effect of the first metal plate 21 having a high thermal expansion coefficient is reduced, and the heat sink function is lowered. Conversely, when the thickness of the first metal plate 21 exceeds 50% of the thickness of the metal substrate 1, cracking of the metal substrate 1 due to heat when the metal substrate 1 is connected to the compound semiconductor layer 3 is suppressed. Can not. That is, a large difference in thermal expansion coefficient between the first metal plate 21 and the compound semiconductor layer 3 may cause cracks in the metal substrate 1 due to heat, leading to poor bonding.
In particular, when copper is used as the first metal plate 21, the total thickness of copper is preferably 5% or more and 40% or less of the thickness of the metal substrate 1, and is preferably 10% or more and 30% or less. It is more preferable that it is 15% or more and 25% or less.
The thickness of the first metal plate 21 is preferably 5 μm or more and 30 μm or less, and more preferably 5 μm or more and 20 μm or less.

<Second metal plate>
When the second metal plate 22 is made of a material having a larger thermal expansion coefficient than the compound semiconductor layer 3 as the first metal plate, the second metal plate 22 is made of a material whose thermal expansion coefficient is smaller than that of the compound semiconductor layer 3. Is preferred. By adopting this configuration, the thermal expansion coefficient of the entire metal substrate is close to the thermal expansion coefficient of the compound semiconductor layer, thus suppressing warpage and cracking of the metal substrate when joining the compound semiconductor layer and the metal substrate. This is because the manufacturing yield of light emitting diodes can be improved. Therefore, when a material having a smaller thermal expansion coefficient than the compound semiconductor layer 3 is used as the first metal plate, the second metal plate 22 is made of a material whose thermal expansion coefficient is larger than that of the compound semiconductor layer 3. It is preferable.

  For example, when an AlGaInP layer (thermal expansion coefficient = about 5.3 ppm / K) is used as the compound semiconductor layer 3, molybdenum (thermal expansion coefficient = 5.1 ppm / K), tungsten (as the second metal plate 22). Thermal expansion coefficient = 4.3 ppm / K), chromium (thermal expansion coefficient = 4.9 ppm / K), and alloys thereof are preferably used.

  The light emitting diode 100 according to an embodiment of the present invention is a light emitting diode 100 in which a metal substrate 1 is bonded to a compound semiconductor layer 3 including a light emitting layer 2, and the metal substrate 1 includes a first metal plate 21 and a second metal plate 1. The first metal plate 21 has a thermal expansion coefficient larger than that of the compound semiconductor layer 3, and the second metal plate 22 has a thermal expansion coefficient of the compound semiconductor layer 3. If a structure made of a material smaller than the above material is employed, heat dissipation is excellent, cracking of the substrate during bonding can be suppressed, and high voltage can be applied to emit light with high luminance.

  The light emitting diode 100 according to an embodiment of the present invention has a configuration in which the material of the second metal plate 22 is a material having a thermal expansion coefficient that is within ± 1.5 ppm / K of the thermal expansion coefficient of the compound semiconductor layer 3. When employed, it is excellent in heat dissipation, can suppress cracking of the substrates during bonding, and can emit light with high brightness by applying a high voltage.

  As the light emitting diode 100 according to an embodiment of the present invention, when the first metal plate 21 employs a configuration made of aluminum, copper, silver, gold, nickel, titanium, tin, or an alloy thereof, the heat dissipation is excellent and the bonding is performed. In this case, cracking of the substrate can be suppressed, and high voltage can be applied to emit light with high luminance.

  When the second metal plate 22 adopts a structure made of molybdenum, tungsten, chromium, or an alloy thereof as the light emitting diode 100 of one embodiment of the present invention, it has excellent heat dissipation and suppresses cracking of the substrate during bonding. It is possible to emit light with high luminance by applying a high voltage.

  As the light emitting diode 100 according to an embodiment of the present invention, the first metal plate 21 is made of copper, the second metal plate 22 is made of molybdenum, and the first metal plate 21 and the second metal plate 22 are layers. Adopting a configuration in which the number of layers is 3 or more and 9 or less, it is excellent in heat dissipation, can suppress the cracking of the substrate during bonding, and can emit light with high luminance by applying a high voltage it can.

[Method for manufacturing light-emitting diode]
Next, the manufacturing method of the light emitting diode which is embodiment of this invention is demonstrated.
A method of manufacturing a light-emitting diode according to an embodiment of the present invention includes a metal substrate including a plurality of metal plates and a metal protective film including one or more films covering at least upper and lower surfaces of the plurality of metal plates, and the metal A step of manufacturing a wafer including a compound semiconductor layer including a light-emitting layer formed on a substrate, a step of removing a portion of the compound semiconductor layer on a planned cutting line by etching, and a compound semiconductor of the metal protective film Removing at least part of at least one film on the surface opposite to the surface provided with the layer by etching to form a positioning mark; and a surface including the compound semiconductor layer based on the positioning mark; Includes a step of irradiating the opposite surface with a laser to cut the metal substrate.
First, the manufacturing process of a metal substrate is demonstrated.

<Manufacturing process of metal substrate>
First, a plurality of metal plates are stacked and hot pressed to form an integral metal plate 1A.

First, two substantially flat plate-like first metal plates 21 (21A, 21B) and one substantially flat plate-like second metal plate 22 are prepared. For example, Cu having a thickness of 10 μm is used as the first metal plate 21 (21A, 21B), and Mo having a thickness of 75 μm is used as the second metal plate 22.
Next, as shown in FIG. 2A, the second metal plate 22 is inserted between the two first metal plates 21, and these are stacked.

Next, the said board | substrate is arrange | positioned to a predetermined pressurization apparatus, and a load is applied to the 1st metal plate 21 and the 2nd metal plate 22 in the direction of the arrow under high temperature. Accordingly, as shown in FIG. 2B, the first metal plate 21 is Cu, the second metal plate 22 is Mo, and Cu (10 μm) / Mo (75 μm) / Cu (10 μm). Three metal plates 1A are formed.
For example, the metal substrate 1 has a thermal expansion coefficient of 5.7 ppm / K and a thermal conductivity of 220 W / m · K.

Next, a metal protective film that covers the entire surface of the metal plate 1A is formed.
Next, as shown in FIG. 2C, a metal protective film 2 that covers the entire surface of the metal plate 1A, that is, the upper surface, the lower surface, and the side surfaces is formed. At this time, the metal plate 1A shown in FIG. 2C is the one before being cut into individual light-emitting diodes, so that the side surface covered by the metal protective film is the outer peripheral side surface of the metal plate (plate). . Therefore, when covering the side surface of the metal plate 1 of each light-emitting diode after separation into pieces with the metal protective film 2, a step of covering the side surface with the metal protective film is performed separately.
FIG. 2 (c) shows a part of the metal plate 1A that is not on the outer peripheral end side, and the metal protective film on the outer peripheral side surface does not appear in the drawing.

  In addition, when performing the semiconductor substrate removal process by the etching liquid later, it is sufficient that the metal protective film covers the entire surface of the metal plate, and in the process after the semiconductor substrate removal process, a part of the metal protective film of the metal plate is formed. The metal substrate of the light-emitting diode that is removed and finally manufactured may not have the entire surface of the metal plate covered with the metal protective film.

A known film forming method can be used for the metal protective film, but a plating method capable of forming a film on the entire surface including the side surface is most preferable.
For example, in the electroless plating method, nickel is then plated with gold, and the metal substrate 1 in which the upper surface, the side surface, and the lower surface of the metal plate are covered with the nickel film and the gold film (metal protective film) can be produced.
The plating material is not particularly limited, and known materials such as copper, silver, nickel, chromium, platinum, and gold can be applied. However, a layer that combines nickel having good adhesion and gold having excellent chemical resistance is optimal.
The plating thickness is not particularly limited, but in the range of durability and cost, 0.2 to 5 μm, preferably 0.5 to 3 μm is an appropriate range. The thickness of expensive gold is desirably 1 μm or less. For example, a stacked structure of nickel of 2 μm and gold on nickel of 1 μm can be formed.
As the plating method, known techniques and chemicals can be used. An electroless plating method that does not require an electrode is simple and desirable.

  After that, after cutting according to the size of the bonding surface of the compound semiconductor layer 3, the surface may be mirror-finished.

<Compound semiconductor layer and second electrode formation step>
First, as shown in FIG. 3, a plurality of epitaxial layers are grown on the one surface 11 a of the semiconductor substrate 11 to form an epitaxial multilayer 17.
The semiconductor substrate 11 is a substrate for forming an epitaxial layered body 17 and is, for example, a Si-doped n-type GaAs single crystal substrate in which one surface 11a is inclined by 15 ° from the (100) plane. As described above, when an AlGaInP layer or an AlGaAs layer is used as the epitaxial multilayer 17, a gallium arsenide (GaAs) single crystal substrate can be used as the substrate on which the epitaxial multilayer 17 is formed.

  As a method for forming the compound semiconductor layer 3, a metal organic chemical vapor deposition (MOCVD) method, a molecular beam epitaxy (MBE) method, or a liquid phase epitaxial (Liquid Phase Epitaxy) method is used. Etc. can be used.

In the present embodiment, the low pressure MOCVD method using trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga), and trimethylindium ((CH ₃ ) ₃ In) as group III constituent elements. Each layer is epitaxially grown using
Note that biscyclopentadienyl magnesium ((C ₅ H ₅ ) ₂ Mg) is used as a Mg doping material. Further, disilane (Si ₂ H ₆ ) is used as a Si doping raw material. Further, phosphine (PH ₃ ) or arsine (AsH ₃ ) is used as a raw material for the group V constituent element.
The p-type GaP layer 13 is grown at 750 ° C., for example, and the other epitaxial growth layers are grown at 730 ° C., for example.

Specifically, first, a buffer layer 12 a made of n-type GaAs doped with Si is formed on one surface 11 a of the semiconductor substrate 11. As the buffer layer 12a, for example, n-type GaAs doped with Si is used, the carrier concentration is 2 × 10 ¹⁸ cm ⁻³ , and the layer thickness is 0.2 μm.
Next, an etching stop layer 12b made of Si-doped n-type (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P is formed on the buffer layer 12a.
The etching stop layer 12b is a layer for preventing the cladding layer and the light emitting layer from being etched when the semiconductor substrate is removed by etching, for example, Si-doped (Al _0.5 Ga _0.5 ) _0. It consists _.5 In _0.5 P, the thickness and 0.5 [mu] m.
Next, a contact layer 12c made of Si-doped n-type GaAs is formed on the etching stop layer 12b.
Next, a cladding layer 10a made of n-type Al _0.5 In _0.5 P doped with Si is formed on the contact layer 12c.
Next, undoped (Al _0.2 Ga _0.8 ) _0.5 In _0.5 P / (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P 10 is formed on the cladding layer 10a. A light emitting layer 2 having a pair of laminated structures is formed.
Next, a clad layer 10b made of p-type Al _0.5 In _0.5 P doped with Mg is formed on the light emitting layer 2.
Next, a Mg-doped p-type GaP layer 13 is formed on the cladding layer 10b.

Next, the surface 13a opposite to the semiconductor substrate 11 of the p-type GaP layer 13 is mirror-polished to a depth of 1 μm from the surface to make the surface roughness within 0.18 nm, for example.
Next, as shown in FIG. 4, a second electrode (ohmic electrode) 8 is formed on the surface 13 a opposite to the semiconductor substrate 11 of the p-type GaP layer 13. For example, the second electrode 8 is formed by laminating Au having a thickness of 0.2 μm on AuBe having a thickness of 0.4 μm. For example, the second electrode 8 has a circular shape of 20 μmφ when viewed in plan, and is formed at intervals of 60 μm.

<Reflection structure forming process>
Next, as shown in FIG. 5, a transparent conductive film 14 made of an ITO film is formed so as to cover the surface 13 a opposite to the semiconductor substrate 11 of the p-type GaP layer 13 and the second electrode 8. Next, a heat treatment at 450 ° C. is performed to form an ohmic contact between the second electrode 8 and the transparent conductive film 14.

Next, as shown in FIG. 6, after a film made of a silver (Ag) alloy is formed on the surface 14 a of the transparent conductive film 14 on the side opposite to the epitaxial laminate 17 by a vapor deposition method, A metal film 15 was formed by forming a film made of nickel (Ni) / titanium (Ti) to a thickness of 0.5 μm and a film made of gold (Au) to a thickness of 1 μm.
Thereby, the reflective structure 4 including the metal film 15 and the transparent conductive film 14 is formed.

<Metal substrate bonding process>
Next, as shown in FIG. 7, the semiconductor substrate 11 on which the reflective structure 4 and the epitaxial laminate 17 are formed, and the metal substrate 1 formed in the manufacturing process of the metal substrate are carried into a decompression device. The bonding surface 4a of the reflective structure 4 and the bonding surface 1a of the metal substrate 1 are arranged to face each other and overlap each other.
Next, after evacuating the inside of the decompression device to 3 × 10 ⁻⁵ Pa, a load of 500 kg is applied in a state where the semiconductor substrate 11 and the metal substrate 1 are heated to 400 ° C. 4a and the joining surface 5a of the metal substrate 1 are joined together to form a joined structure 18.

<Semiconductor substrate and buffer layer removal step>
Next, as shown in FIG. 8, the semiconductor substrate 11 and the buffer layer 12a are selectively removed from the bonding structure 18 with an ammonia-based etchant.
At this time, since the metal substrate of the present invention is covered with the metal protective film and has high resistance to the etchant, the quality of the metal substrate is prevented from being deteriorated.

<Etching stop layer removal process>
Next, the etching stop layer 12b is selectively removed with a hydrochloric acid-based etchant. Thereby, the compound semiconductor layer 3 having the light emitting layer 2 is formed.
At this time, since the metal substrate of the present invention is covered with the metal protective film and has high resistance to the etchant, the quality of the metal substrate is prevented from being deteriorated.

<First electrode forming step>
Next, a conductive film for an electrode is formed on the surface 3a of the compound semiconductor layer 3 opposite to the reflective structure 4 by using a vacuum deposition method. As the electrode conductive film, for example, a metal plate structure made of AuGe / Ni / Au can be used. For example, AuGe (Ge mass ratio 12%) is formed to a thickness of 0.15 μm, Ni is then formed to a thickness of 0.05 μm, and Au is further formed to a thickness of 1 μm.
Next, by using a general photolithography means, the electrode conductive film is patterned into a circular shape in plan view, for example, and a light emitting diode wafer is produced as an n-type ohmic electrode (first electrode) 6. To do.

Of the contact layer 12c, for example, ammonia water (NH ₄ OH) / hydrogen peroxide (H ₂ O ₂ ) / pure water (H ₂ 0) using the mask used in the patterning in the first electrode formation step. The portion other than the bottom of the n-type ohmic electrode (first electrode) 6 is removed by etching with the mixed solution. As a result, the planar shapes of the n-type ohmic electrode (first electrode) 6 and the contact layer 12c are substantially the same as shown in FIG.

  After that, it is preferable to alloy each metal of the n-type ohmic electrode (first electrode) 6 by performing heat treatment at 420 ° C. for 3 minutes, for example. Thereby, the resistance of the n-type ohmic electrode (first electrode) 6 can be reduced.

With reference to FIG. 9A to FIG. 9C, a process of removing a portion of the compound semiconductor layer on the planned cutting line (front surface etching process) will be described.
In FIGS. 9A to 9C, only the part from the front surface provided with the compound semiconductor layer to the metal substrate is shown.

<Compound semiconductor layer removal step>
First, as shown in FIG. 9A, a resist is applied on the compound semiconductor layer 3 of the light emitting diode wafer, and a resist pattern 31 including a line pattern to be cut having a width of about 60 μm is formed by photolithography, for example. .

Next, the exposed portion of the compound semiconductor layer on the line to be cut is removed by etching (see reference numeral 3A).
The removal width of the compound semiconductor layer determines the removal width of the subsequent metal plate. Accordingly, the removal width of the compound semiconductor layer is preferably wider than the cutting width by the laser in order to reduce the amount of debris generated during the subsequent laser cutting. For example, when laser cutting is performed by laser irradiation from the front surface, the width is preferably about 40 μm wider than the laser cutting width. Further, when laser cutting is performed by laser irradiation from the back surface, the cutting width by the laser is preferably about 20 μm wide.

  Next, as shown in FIG. 9B, the wafer is immersed in a ferric chloride solution, and the portions of the ITO layer 14 and the Ni layer 33 located below the portion where the compound semiconductor layer is removed are etched. (See reference numerals 14A and 33A).

  Next, as shown in FIG. 9C, the wafer is immersed in a hydrofluoric acid-based liquid, for example, a solution obtained by adding water to hydrogen difluoride 2-3% and ammonium fluoride 0.05-0.1%. Then, the portion of the Ti layer 34 located below the removed portion is removed by etching (see reference numeral 34A).

  Next, the wafer is immersed in an Au-based etching solution, for example, a cyan-based etching solution, and the portions of the Au layer 35 and Au layer 36 located below the removed portion are etched and removed (reference numeral 35A, 36A).

Next, the wafer is immersed in a ferric chloride solution whose etching rate for Ni is higher than that for Mo and can selectively etch Ni, and the portion of the Ni layer 37 located below the removed portion is Cu. Etching is performed until the layer 21A is exposed (see reference numeral 37A).
In this step, if the Cu layer 21A is exposed by controlling the etching time, the etching can be stopped. However, the ferric chloride solution has a higher etching rate for Cu than that for Mo, so Etching may be performed up to the layer 21A.

  By the above procedure, the compound semiconductor layer on the cutting line can be removed.

<Positioning mark formation process>
Referring to FIGS. 10A to 10C, at least a part of at least one film on the surface opposite to the surface provided with the compound semiconductor layer of the metal protective film is removed by etching. A process of forming the positioning mark will be described.
In FIGS. 10A to 10C, only a part of the metal substrate on the opposite side of the front surface provided with the compound semiconductor layer is illustrated.

  The purpose of the positioning mark formation is to form a mark used for positioning (alignment) of laser dicing and to reduce debris by removing a part of the metal protective film for that purpose. If the former is important, the removal amount of the metal protective film may be small, but if the latter is important, it is preferable to increase the removal amount of the metal protective film. In order to sufficiently fulfill both purposes, it is preferable to remove a portion of the metal protective film corresponding to the entire line to be cut (street).

As a method of eliminating the dicing deviation of laser dicing, after applying a resist having a pattern having a street opening similar to etching the metal protective film, the resist is applied without etching the metal protective film. Dicing can be considered. In this method, the debris can be removed by adhering to the resist, but the debris removal is incomplete, and problems such as degeneration or burning of the resist due to heat may occur. Conceivable.
Although a method of forming a film patterned by sputtering or the like for the positioning mark (forming a convex part on the dicing line) is also conceivable, it is not a countermeasure against debris, and the material cost increases. There is.

First, as shown in FIG. 10A, a resist is applied on the metal protective film (Au / Ni layer) formed on the metal substrate 1 on the back surface of the light emitting diode wafer, and the positioning mark is formed by photolithography. A resist pattern 41 from which a portion (at least a portion) corresponding to the shape is removed is formed.
The shape of the positioning mark is not limited as long as it functions as a mark used for laser dicing positioning (alignment), but the shape of only the cross section of the planned cutting line (street) and the number of planned cutting lines (street) A mark may be formed at a location.
It is preferable that the entire portion on the line to be cut is used as a positioning mark and the metal protective film in that portion is removed, so that the amount of debris generated by laser dicing can be further reduced.

  Next, as shown in FIG. 10B, the wafer is immersed in an Au-based etching solution, for example, a cyan-based etching solution, and is positioned below the removed portion of the Au layer (at least one film) 42. A portion to be etched is removed by etching to form a positioning mark (portion indicated by reference numeral 42A).

  Through the above procedure, at least a part of at least one of the surfaces of the metal protective film opposite to the surface provided with the compound semiconductor layer is removed by etching to form a positioning mark.

  In the present embodiment, only one Au layer of the metal protective film having a two-layer structure of Au / Ni layers is etched, but both Au / Ni layers may be etched. In the case of three or more layers, all the layers may be removed or some of them may be removed.

<Laser dicing process>
Next, the metal substrate is cut by irradiating the surface opposite to the surface provided with the compound semiconductor layer with the positioning mark formed by etching away a part of the metal protective film in the previous process as a mark To do.

The laser cutting conditions may be those used in the LED element manufacturing process.
For example, the metal substrate can be cut under conditions where the laser wavelength is 355 nm and the feed rate is 20 mm / sec.

  Laser scanning of laser dicing may be performed in a plurality of times. At that time, dicing may be performed by changing the thickness of the laser beam.

  The laser cut surface of the metal substrate is then preferably Au plated.

<Light emitting diode lamp>
A light-emitting diode lamp including a light-emitting diode according to an embodiment of the present invention will be described.
FIG. 11 is a schematic cross-sectional view showing an example of a light-emitting diode lamp according to an embodiment of the present invention. As shown in FIG. 11, a light emitting diode lamp 50 according to an embodiment of the present invention is mounted on a package substrate 55, two electrode terminals 53 and 54 formed on the package substrate 55, and the electrode terminal 54. The light emitting diode 100 and a transparent resin (sealing resin) 51 made of silicon or the like formed so as to cover the light emitting diode 100 are included.
The light emitting diode 100 includes the compound semiconductor layer 3, the reflection structure 4, the metal substrate 1, the first electrode 6, and the second electrode 8, and is disposed so that the metal substrate 1 is connected to the electrode terminal 53. Has been. The first electrode 6 and the electrode terminal 54 are wire bonded. The voltage applied to the electrode terminals 53 and 54 is applied to the compound semiconductor layer 3 through the first electrode 6 and the second electrode 8, and the light emitting layer included in the compound semiconductor layer 3 emits light. The emitted light is extracted in the front direction f.

The package substrate 55 has a thermal resistance of 10 ° C./W or less. Thereby, even when 1 W or more of electric power is applied to the light emitting layer 2 to emit light, it can function as a heat sink, and the heat dissipation of the light emitting diode 100 can be further enhanced.
The shape of the package substrate is not limited to this, and a package substrate having another shape may be used. Also in LED lamp products using package substrates of other shapes, sufficient heat dissipation can be ensured, so that a light-emitting diode lamp with high output and high brightness can be obtained.

First, the light emitting layer has a laminated structure of 10 pairs of (Al _0.2 Ga _0.8 ) _0.5 In _0.5 P / (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P. The thickness is 4 μm, the GaP layer is 2 μm, the reflective structure is Ag layer 0.7 μm, the Ni / Ti barrier layer 0.5 μm, the Au layer 1 μm, the metal substrate is Cu plate 10 μm / Mo plate 75 μm / Cu plate 10 μm. A wafer made of an Ni layer having a thickness of 2 μm and an Au layer having a thickness of 1 μm as metal protective films on both sides of the layer structure was produced.

On the front surface of the wafer, the metal protective film (Ni layer and Au layer) on the front surface side of the metal substrate was removed by etching to form a groove having a width of 60 μm. For the back surface, only the Au layer on the back surface side of the metal substrate was removed by etching to form a groove having a width of 40 μm.
Next, the metal substrate was laser-cut from the back surface of the wafer under the conditions of a laser wavelength of 355 nm and a feed rate of 20 mm / sec.

The chip-shaped light emitting diode thus fabricated was observed with a laser microscope.
Although debris was attached to the side surface on the back side of the metal substrate, debris attached to the side surface of the compound semiconductor layer on the front side and the exposed surface of the metal protective film on the back side was observed. Was not.

  INDUSTRIAL APPLICABILITY The present invention can be used in a light emitting diode manufacturing method using a metal substrate as a substrate, a cutting method, and an industry using the light emitting diode.

DESCRIPTION OF SYMBOLS 1 Metal substrate 1A Metal plate 1Aa Upper surface 1Ab Lower surface 1Aaa Side surface 1B, 1Ba, 1Bb Metal protective film 2 Light emitting layer 3 Compound semiconductor layer 4 Reflective structure 10a, 10b Clad layer 13 Current diffusion layer 14 Transparent conductive film 15 Metal film 21 (21A 21B) First metal plate 22 Second metal plate 50 Light emitting diode lamp 100 Light emitting diode (light emitting diode chip)

Claims (12)

In a method of manufacturing a chip-like light emitting diode by irradiating a laser on a wafer,
A metal substrate comprising a plurality of metal plates and a metal protective film comprising one or more films covering at least upper and lower surfaces of the plurality of metal plates; and a compound semiconductor layer including a light emitting layer formed on the metal substrate; Producing a wafer comprising:
Removing the portion of the compound semiconductor layer on the line to be cut by etching;
A step of removing at least a part of at least one of the surfaces of the metal protective film opposite to the surface provided with the compound semiconductor layer by etching to form a positioning mark;
A step of irradiating a laser on a surface opposite to the surface provided with the compound semiconductor layer based on the positioning mark to cut the metal substrate;
A method for producing a light emitting diode, comprising:   The plurality of metal plates include a metal plate made of a material having a thermal expansion coefficient larger than that of the compound semiconductor layer, and a metal plate made of a material having a thermal expansion coefficient smaller than that of the compound semiconductor layer. The method of manufacturing a light emitting diode according to claim 1, comprising:   The material having a thermal expansion coefficient larger than that of the compound semiconductor layer is made of aluminum, copper, silver, gold, nickel, titanium, tin, or an alloy thereof. The manufacturing method of the light emitting diode in any one of.   4. The material according to claim 1, wherein the material having a thermal expansion coefficient smaller than that of the compound semiconductor layer is made of molybdenum, tungsten, chromium, or an alloy thereof. 5. Manufacturing method of light emitting diode.   The method of manufacturing a light emitting diode according to any one of claims 1 to 4, wherein the plurality of metal plates are made of three metal plates.   6. The method of manufacturing a light emitting diode according to claim 5, wherein, of the three metal plates, two metal plates sandwiching one metal plate are made of the same metal material.   7. The method of manufacturing a light emitting diode according to claim 6, wherein the one metal plate is made of molybdenum, and the two metal plates are made of copper.   The method for manufacturing a light emitting diode according to any one of claims 1 to 7, wherein the metal protective film is made of any one of aluminum, silver, gold, nickel, titanium, tin, or an alloy thereof.   The method for manufacturing a light emitting diode according to claim 1, wherein the light emitting layer includes an AlGaInP layer or an AlGaInAs layer.   The method for manufacturing a light emitting diode according to claim 1, further comprising a reflective structure between the compound semiconductor layer and the metal substrate. A wafer comprising a metal substrate comprising a plurality of metal plates, a metal protective film comprising one or more films covering at least the upper and lower surfaces of the plurality of metal plates, and a compound semiconductor layer formed on the metal substrate. In the method of cutting the chip-like light emitting diode by irradiating the laser to
Removing the portion of the compound semiconductor layer on the line to be cut by etching;
A step of removing at least a part of at least one of the surfaces of the metal protective film opposite to the surface provided with the compound semiconductor layer by etching to form a positioning mark;
A step of cutting the metal substrate by irradiating a laser based on the positioning mark in plan view;
The cutting method characterized by having.   The light emitting diode manufactured by the manufacturing method of the light emitting diode as described in any one of Claim 1 to 10.

Images