WO2012005185A1 - Method of producing light-emitting diodes, cutting method, and light-emitting diode - Google Patents

Abstract

Disclosed are a method for producing light-emitting diodes and a cutting method with which defects such as dicing line misalignments caused by heat generated during laser cutting of a metal substrate can be prevented, and with which adverse effects due to debris produced during cutting can be reduced. Also disclosed is a light-emitting diode. The method for producing light-emitting diodes comprises: a step for manufacturing a wafer provided with a metal substrate comprising a plurality of metal layers, and a compound semiconductor layer containing a light-emitting layer formed on said metal substrate; a step for removing part of the compound semiconductor layer on the intended cutting line by etching; a step for removing part of at least one of the plurality of metal layers on the opposite side to the laser irradiation surface on the intended cutting line by etching; and a step for cutting the metal substrate by irradiating a laser along the part removed from the metal layer in a plan view.

Description

Light emitting diode manufacturing method, cutting method, and light emitting diode

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.
This application claims priority on July 9, 2010 based on Japanese Patent Application No. 2010-156722 filed in Japan, the contents of which are incorporated herein by reference.

Conventionally, as a high-power light-emitting diode (an abbreviation: LED) that emits red and infrared light, a light _- emitting layer made of aluminum gallium arsenide (compositional formula Al _X Ga _1-X As; 0 ≦ X ≦ 1) is provided. 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.

A light emitting diode using a metal substrate is 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 2005-236303 A JP 2006-13499 A

However, in the cutting of the metal substrate by blade dicing, there is a problem that the cutting is not easy because the blade is easily 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, when cutting metal substrates by laser dicing, the effect of heat generated during cutting becomes a problem.

Specifically, in a metal substrate in which dissimilar metals (for example, Mo and Cu) are bonded, they are bonded in a state having different extension widths corresponding to the thermal expansion coefficient of each metal at the time of bonding. Has a stress at its interface. For example, when the metal substrate is composed of three metal layers of the first to third metal layers, the first metal layer is cut in the second metal layer when the first metal layer is cut by laser dicing (laser cutting). Although the interfacial stress is released on the surface on the metal layer side, the interfacial stress remains on the surface on the third metal layer side, so that the balance of stress is lost during cutting, and the metal substrate is distorted. As a result, there arises a problem that the dicing line is shifted from the intended position, the chip division property is deteriorated, and the light emitting diode chip becomes an abnormal shape.

Also, there is a problem that the metal substrate expands due to heat generation and the pitch width of dicing becomes inaccurate. That is, when the substrate is cut in an expanded state, and after returning to the normal size after cutting, the pitch width is different from that at the time of cutting. This problem is exacerbated because a thicker metal substrate generates more heat.

Furthermore, there is a problem in that die bonding is affected if the shape of the back side of the light emitting diode chip changes due to heat.

Further, in the cutting of the metal substrate by laser dicing, debris generated at the time of cutting 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. Become.

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

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 can prevent inconveniences such as deviation of a dicing line due to heat generated during cutting of a metal substrate by laser dicing, and reduce adverse effects due to debris generated during cutting. An object of the present invention is to provide a method for manufacturing a light emitting diode, a cutting method, and 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,
Etching a portion of a compound semiconductor layer on a planned cutting line of a wafer comprising a metal substrate composed of a plurality of metal layers and a compound semiconductor layer including a light emitting layer formed on the metal substrate; Removing the portion of the plurality of metal layers on the line to be cut of at least one layer opposite to the laser irradiation surface by etching, and removing the metal layer in plan view. And a step of cutting the metal substrate by irradiating a laser along the formed portion.
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.
In addition, “a plurality of metal layers” are, for example, two adjacent metal layers formed in two stages, and those made of the same metal material are a single metal layer and a single metal layer. In this case, at least the adjacent metal layers are made of different kinds of metal materials.
(2) prior to the step of cutting the metal substrate, at least one layer of the laser irradiation surface side of the plurality of metal layers, that the portion on the cutting line further comprising the step of removing by etching A method for producing a light-emitting diode according to item (1), which is characterized in that
(3) The plurality of metal layers include a material having a thermal expansion coefficient larger than that of the compound semiconductor layer and a material having a thermal expansion coefficient smaller than that of the compound semiconductor layer. The method for producing a light-emitting diode according to any one of (1) and (2).
(4) The item (1) above, wherein the material having a thermal expansion coefficient larger than that of the compound semiconductor layer is any one of aluminum, copper, silver, gold, nickel, titanium, or an alloy thereof. The manufacturing method of the light emitting diode as described in any one of (3).
(5) Any one of (1) to (4) above, wherein the material having a thermal expansion coefficient smaller than that of the compound semiconductor layer is any one of molybdenum, tungsten, chromium, or an alloy thereof. A method for producing a light-emitting diode according to claim 1.
(6) The method for manufacturing a light-emitting diode according to any one of (1) to (5), wherein the plurality of metal layers are three metal layers.
(7) The method for manufacturing a light-emitting diode according to (6) above, wherein, of the three metal layers, two metal layers sandwiching one metal layer are made of the same metal material.
(8) The method for manufacturing a light-emitting diode according to (7), wherein the one metal layer is made of molybdenum, and the two metal layers are made of copper.
(9) From the preceding paragraph (6), wherein two metal layers sandwiching one metal layer are removed by etching out of the three metal layers, and the one metal layer is cut by a laser. The manufacturing method of the light emitting diode as described in any one of 8).
(10) The method for manufacturing a light-emitting diode according to any one of (1) to (9), wherein the light-emitting layer includes an AlGaInP layer or an AlGaAs layer.
(11) The method for producing a light-emitting diode according to any one of (1) to (10), wherein a reflective structure is provided between the compound semiconductor layer and the metal substrate.
(12) In a method of cutting a chip-shaped light emitting diode by irradiating a laser on a wafer comprising a metal substrate composed of a plurality of metal layers and a compound semiconductor layer formed on the metal substrate,
The cut portion on the line of said compound semiconductor layer, and removing by etching at least one layer of the opposite side of the laser irradiation surface of the plurality of metal layers, a portion on the line to cut, etched away And cutting the metal substrate by irradiating a laser along the removed portion of the metal layer in plan view.
(13) before the step of cutting the metal substrate, at least one layer of the laser irradiation surface side of the plurality of metal layers, that the portion on the cutting line further comprising the step of removing by etching The cutting method according to item (12), wherein the cutting method is characterized.
(14) A light-emitting diode manufactured by the method for manufacturing a light-emitting diode according to any one of (1) to (13).
(15) and the metal substrate including a plurality of metal layers, a light emitting diode that includes a compound semiconductor layer including a light emitting layer formed on the metal substrate, the side surface of the metal substrate, the thickness of the metal substrate The wet etching surface and the laser cutting surface arranged side by side in the vertical direction, and among the plurality of metal layers, at least one side surface of at least one metal layer on the compound semiconductor layer side and at least one layer on the opposite side of the compound semiconductor layer The light emitting diode according to claim 1, wherein the side surface of the metal layer is a wet-etched surface, and a by-product generated by laser irradiation adheres only to the side surface of the metal substrate.
(16) The plurality of metal layers are three metal layers, the side surfaces of the two metal layers sandwiching one metal layer are formed by a wet etching surface, and the side surfaces of the one metal layer are formed by a laser cut surface. The light-emitting diode according to item (15), wherein
(17) The light emitting diode according to (16), wherein the one metal layer is made of molybdenum, and the two metal layers are made of copper.

According to the method for manufacturing a light-emitting diode according to the present invention, the step of removing at least one portion of the plurality of metal layers on the cutting line on the opposite side of the laser irradiation surface by etching, and the metal in plan view And a step of cutting the metal substrate by irradiating a laser along the removed portion of the layer, so that the portion on the cutting line of the metal layer on the side opposite to the side irradiated with the laser by etching is previously By removing the interface stress between the metal layer adjacent to the metal layer in advance, it is possible to reduce the degree to which the balance of stress in the metal substrate is lost during laser cutting. Although it is necessary to consider a decrease in mechanical strength due to etching, if the number of metal layers to be etched is increased, the degree to which the balance of stress is lost during laser cutting can be further reduced. The higher the mechanical strength of the metal layer left unetched (eg, molybdenum), the more metal layers can be etched.
As a result, the degree of stress balance in the metal substrate during laser cutting is reduced. As a result, the degree to which the metal substrate is distorted can be reduced, the degree to which the dicing line is displaced from the intended position can be reduced, and the chip can be divided. It can be maintained well, and the light emitting diode chip can be prevented from becoming an abnormal shape.
In addition, since laser cutting is performed by aligning several interfacial stresses among a plurality of interfacial stresses, the degree to which the dicing line deviates from the intended position can be reduced. .
Furthermore, the thickness of the metal substrate to be laser cut is reduced by removing the portion of the metal layer on the planned cutting line by etching, so that the amount of heat generated during laser cutting is reduced, and the metal substrate due to heat generation is reduced. Expansion can be suppressed, and as a result, fluctuations in the pitch width of dicing can be reduced, and it is possible to prevent the shape of the back surface side of the light-emitting diode chip from changing due to heat.
Furthermore, since the metal substrate is composed of a plurality of metal layers, etching can be performed for each metal layer using the etching selectivity, and the etching depth of the metal substrate can be easily controlled.
Furthermore, instead of laser cutting the entire metal layer, the amount of metal to be laser cut is reduced by removing a part by etching, so the amount of debris generated during laser cutting is reduced and the light emitting layer is reduced. It is possible to prevent a short circuit due to contact with the side surface of the compound semiconductor layer. Further, debris can be prevented from adhering to the front surface and the back surface of the metal substrate, or the amount of adhesion can be reduced, so that appearance defects can be reduced, and wire bonding defects and die bonding defects can be reduced.

According to the manufacturing method of a light-emitting diode according to the present invention, the step of removing before the step of cutting the metal substrate, at least one layer of the laser irradiation surface side of the plurality of metal layers, a portion of the cutting line by etching Since the portion on the planned cutting line of the metal layer on the laser irradiation side is previously removed by etching, the amount of the metal substrate to be laser cut is reduced, and the amount of debris generated is reduced. be able to.
Further, by this arrangement, when the laser irradiation surface is a compound semiconductor layer side containing the light-emitting layer, the metal layer of the surface side is etched, the position of the metal substrate laser cutting is started Becomes far from the compound semiconductor layer. As a result, the debris does not reach the compound semiconductor layer and can be prevented from being short-circuited, and the yield can be improved.

According to the light emitting diode manufacturing method of the present invention, the plurality of metal layers are made of a material having a thermal expansion coefficient larger than that of the compound semiconductor layer and a material having a thermal expansion coefficient smaller than that of the compound semiconductor layer. By adopting a configuration including the thermal expansion coefficient of the entire metal substrate (the ratio of the length and volume of the metal substrate that actually appears with respect to the temperature rise) is close to the thermal expansion coefficient of the compound semiconductor layer. Therefore, since the difference between the thermal expansion amount of the metal substrate and the thermal expansion amount of the compound semiconductor layer when bonding the compound semiconductor layer and the metal substrate is reduced, the interface generated between the compound semiconductor layer and the metal substrate As a result, one of the interfacial stresses existing on the compound semiconductor layer side and the opposite side of the compound semiconductor layer of the metal substrate is first released during laser cutting. Distortion of the metal substrate can be reduced by as.

According to the method for manufacturing a light-emitting diode according to the present invention, a configuration in which a plurality of metal layers are formed as a three-layer metal layer, so that the metal layer on the side opposite to the laser-irradiated surface is removed by etching and the dicing line shift or The fluctuation of the dicing pitch width can be reduced. In addition, the amount of generated debris can be reduced only by etching and removing the metal layer on the laser irradiation surface side, and the debris can be prevented from adhering to the compound semiconductor layer and short-circuiting, thereby improving the yield. .

According to the method for manufacturing a light emitting diode according to the present invention, a plurality of metal layers are made into three metal layers, and two metal layers sandwiching one metal layer among the three metal layers are made of the same metal material. By adopting a structure, two metal layers sandwiching one metal layer can be etched using the same etchant, which is economical and simple, and the two metal layers are simultaneously removed by etching. Can also reduce the process time.

According to the method for manufacturing a light-emitting diode according to the present invention, the plurality of metal layers is a three-layer metal layer, and among the three metal layers, the two metal layers sandwiching one metal layer are made of copper, Since the metal layer of one layer is made of molybdenum, the mechanical strength of molybdenum is strong. Therefore, even if the metal layer made of copper is etched deeply, the stability of the metal substrate can be maintained.

According to the cutting method according to the present invention, the opposite side of the at least one layer of the laser irradiation surface of the plurality of metal layers, a portion on the line to cut, removing by etching, is the removal of the metal layer And cutting the metal substrate by irradiating a laser along the portion, so that the portion on the cutting line of the metal layer on the side opposite to the laser irradiation side by etching is removed in advance to remove the metal layer. The interfacial stress between the metal layer and the adjacent metal layer is released in advance to reduce the degree of stress balance in the metal substrate during laser cutting, and as a result, the degree to which the metal substrate is distorted can be reduced, resulting in the expected dicing line. The degree of deviation from the position can be reduced, the splitting property of the chip can be maintained well, and the light emitting diode chip can be prevented from having an abnormal shape.
In addition, since laser cutting is performed by aligning several interfacial stresses among the multiple interfacial stresses, the degree to which the dicing line deviates from the intended position is reduced. can do.
Furthermore, the thickness of the metal substrate to be laser cut is reduced by removing the portion of the metal layer on the planned cutting line by etching, so that the amount of heat generated during laser cutting is reduced, and the metal substrate due to heat generation is reduced. Expansion can be suppressed. As a result, fluctuations in the pitch width of dicing can be reduced, and changes in the shape of the back surface side of the light-emitting diode chip due to the influence of heat can be prevented.
Furthermore, since the metal substrate is composed of a plurality of metal layers, etching can be performed for each metal layer using the etching selectivity, and the etching depth of the metal substrate can be easily controlled.

According to the cutting method according to the present invention, before the step of cutting the metal substrate, at least one layer of the laser irradiation surface of the plurality of metal layers, a portion of the cutting line further comprising the step of removing by etching as configuration, since the previously removed cut portion on the line side of the metal layer to laser radiation by etching, can be the amount of the metal substrate to be laser cutting is reduced, to reduce the debris amount produced.
Also, with this configuration, when the laser irradiation surface is on the side of the compound semiconductor layer including the light emitting layer, the metal layer on the surface side is etched, so the position of the metal substrate where laser cutting is started Becomes far from the compound semiconductor layer. As a result, the debris does not reach the compound semiconductor layer and can be prevented from being short-circuited, and the yield can be improved.

The light emitting diode according to the present invention is a light emitting diode comprising a metal substrate composed of a plurality of metal layers and a compound semiconductor layer including a light emitting layer formed on the metal substrate, wherein the side surface of the metal substrate is A wet etching surface and a laser cutting surface arranged side by side in the thickness direction of the metal substrate, and of the plurality of metal layers, the side surface of at least one metal layer on the compound semiconductor layer side and the opposite side of the compound semiconductor layer The side surface of at least one of the metal layers consists of a wet-etched surface, and by-products generated by laser irradiation are deposited only on the side surfaces of the metal substrate, so that debris adheres to the front and back surfaces of the metal substrate. The appearance is improved compared to conventional light emitting diodes.

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 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 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) 1 according to an embodiment of the present invention includes a metal substrate 5 composed of a plurality of metal layers 21A, 22 and 21B, and a light emitting layer 2 formed on the metal substrate 5. A light-emitting diode 1 having a compound semiconductor layer 3 including a side surface 5aa of a metal substrate 5 includes a wet etching surface and a laser cutting surface arranged side by side in the thickness direction of the metal substrate 5, and a plurality of metals Among the layers, the side surface 21Ba of at least one metal layer from the side far from the compound semiconductor layer is a wet etching surface, and the side surface 22a of the metal layer and the side surface 21Aa of the metal layer near the compound semiconductor layer are laser cutting surfaces. The by-products generated by laser irradiation are attached only to the side surface 5aa of the metal substrate 5.
The side surface 21Aa of the metal layer far from the compound semiconductor layer may be a wet etching surface.

<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 AlGaAs layer, which has high light emission efficiency and has established a substrate bonding technique, can be used. The AlGaInP layer is a layer made of a material represented by the general formula (Al _X Ga _1-X ) _Y In _1-YP (0 ≦ X ≦ 1, 0 <Y ≦ 1). This composition is determined according to the emission wavelength of the light emitting diode. Similarly, in the case of an AlGaAs layer used when manufacturing red and infrared light emitting diodes, the composition of the constituent material is determined in accordance with the emission wavelength of the light emitting diode.
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, n-type Al _0.5 In _0.5 P doped with Si, has a carrier concentration of 3 × 10 ¹⁸ cm ⁻³ , and a layer thickness of 0.5 μm.

The light emitting layer 2 includes, for example, 10 pairs of 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. It consists of a laminated structure 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>
The first electrode 6 and the second electrode 8 are each ohmic electrode, their shape and arrangement, as long as it can uniformly diffuse current to the compound semiconductor layer 3 is not particularly limited. 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 wire bonding.

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.

<Metal substrate>
The metal substrate 5 is composed of a plurality of metal layers.
A bonding surface 5a of the metal substrate 5 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 5 is preferably 50 μm or more and 150 μm or less.
When the thickness of the metal substrate 5 is thicker than 150 μm, the manufacturing cost of the light emitting diode increases, which is not preferable. In addition, when the thickness of the metal substrate 5 is less than 50 μm, cracking, hooking, warping, etc. easily occur during handling, which may reduce the manufacturing yield.

As the configuration of the plurality of metal layers, two types of metal layers, that is, a structure in which the first metal layer 21 and the second metal layer 22 are alternately laminated are preferable.
The total number of first metal layers 21 and second metal layers 22 per metal substrate is preferably 3 to 9 layers, more preferably 3 to 5 layers.
When the first metal layer 21 and the two layers fit the number of layers of the second metal layer 22, the thermal expansion in the thickness direction becomes unbalanced, warpage of the metal substrate 5 is generated. Conversely, when more than the first metal layer 21 and 9 layers combined number of layers of the second metal layer 22 includes a first metal layer 21 the layer thickness of the second metal layer 22 Each needs to be thin. It is difficult to manufacture a single-layer substrate made of the first metal layer 21 or the second metal layer 22 with a thin layer thickness. The thickness of each layer is not 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 first metal layers 21 and second metal layers 22 is an odd number in total.
In particular, as the three layers, the two metal layers sandwiching one metal layer are preferably made of the same metal material. In this case, the portion corresponding to the line to be cut can be removed by wet etching using the same etchant between the two metal layers sandwiched.

<First metal layer>
The first metal layer 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 layer. 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 layer, the first metal layer 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 layer 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 layer 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 layer 21 and the thickness of the second metal layer 21 may be different. Furthermore, when the metal substrate 5 is formed of the plurality of first metal layers 21 and the second metal layers 22, the thicknesses of the respective layers may be different from each other.

It is preferable to form a bonding auxiliary film for stabilizing electrical contact or a eutectic metal for die bonding on the bonding surface 5 a and the opposite surface 5 b of the metal substrate 5.
In the case of using the Au-based eutectic metal as the connection for the metal of the metal film 15 of the reflector structure, the bonding surface 5a of the metal substrate 5 is preferably formed of Ni / Au film from the metal substrate 5 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.

Note that the method of bonding the metal substrate 5 to the compound semiconductor layer 3 is not limited to the method described above, and known techniques such as diffusion bonding, an adhesive, and a room temperature bonding method can also be applied.

The total thickness of the first metal layer 21 is preferably 5% to 50%, more preferably 10% to 30%, and more preferably 15% to 25% of the thickness of the metal substrate 5. More preferably, it is as follows. If the total thickness of the first metal layer 21 is less than 5% of the thickness of the metal substrate 5, the effect of the thermal expansion coefficient is higher the first metal layer 21 is reduced, the heat sink function is lowered. Conversely, when the thickness of the first metal layer 21 exceeds 50% of the thickness of the metal substrate 5, cracking of the metal substrate 5 due to heat when the metal substrate 5 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 layer 21 and the compound semiconductor layer 3 may cause cracks in the metal substrate 5 due to heat, resulting in a bonding failure.
In particular, when copper is used for the first metal layer 21, the total thickness of copper is preferably 5% to 40% of the thickness of the metal substrate 5, and is preferably 10% to 30%. It is more preferable that it is 15% or more and 25% or less.
The thickness of the first metal layer 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 layer>
The second metal layer 22 is made of a material whose thermal expansion coefficient is smaller than that of the compound semiconductor layer 3 when a material having a larger thermal expansion coefficient than that of the compound semiconductor layer 3 is used as the first metal layer. 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 that of the compound semiconductor layer 3 is used as the first metal layer, the second metal layer 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 layer 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 1 according to an embodiment of the present invention is a light emitting diode 1 in which a metal substrate 5 is bonded to a compound semiconductor layer 3 including a light emitting layer 2, and the metal substrate 5 includes a first metal layer 21 and a second metal layer 5. The first metal layer 21 has a larger coefficient of thermal expansion than the material of the compound semiconductor layer 3, and the second metal layer 22 has a coefficient of thermal expansion 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.

As the light-emitting diode 1 according to an embodiment of the present invention, a configuration in which the material of the second metal layer 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 1 according to an embodiment of the present invention, when the first metal layer 21 adopts a configuration made of aluminum, copper, silver, gold, nickel, or an alloy thereof, the substrate is excellent in heat dissipation and bonded. Can be suppressed, and high voltage can be applied to emit light with high brightness.

When the second metal layer 22 is made of molybdenum, tungsten, chromium, or an alloy thereof as the light-emitting diode 1 according to an embodiment of the present invention, the heat dissipation is excellent, and cracking of the substrate during bonding is suppressed. It is possible to emit light with high luminance by applying a high voltage.

As the light emitting diode 1 according to the embodiment of the present invention, the first metal layer 21 is made of copper, the second metal layer 22 is made of molybdenum, and the first metal layer 21 and the second metal layer 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 step of manufacturing a wafer including a metal substrate including a plurality of metal layers and a compound semiconductor layer including a light emitting layer formed on the metal substrate; the cut portion on the line of said compound semiconductor layer, and removing by etching at least one layer of the opposite side of the laser irradiation surface of the plurality of metal layers, a portion on the line to cut, etched away And a step of irradiating a laser along the removed portion of the metal layer in plan view to cut the metal substrate.
First, the manufacturing process of a metal substrate is demonstrated.

<Manufacturing process of metal substrate>
As the metal substrate 5, a first metal layer having a thermal expansion coefficient larger than the material of the compound semiconductor layer 3 and a second metal layer having a thermal expansion coefficient smaller than the material of the compound semiconductor layer 3 are adopted and hot pressed. Form.

First, two substantially flat plate-like first metal plates 21 and one substantially flat plate-like second metal plate 22 are prepared. For example, 10 μm thick Cu is used as the first metal plate 21, and 75 μm thick Mo 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. Thus, as shown in FIG. 2B, the first metal layer 21 is Cu, the second metal layer 22 is Mo, and the three layers of Cu (10 μm) / Mo (75 μm) / Cu (10 μm) are used. A metal substrate 5 is formed.
For example, the metal substrate 5 has a thermal expansion coefficient of 5.7 ppm / K and a thermal conductivity of 220 W / m · K.

After that, after cutting according to the size of the bonding surface of the compound semiconductor layer 3, the surface may be mirror-finished.
Further, a bonding auxiliary film may be formed on the bonding surface 5a of the metal substrate 5 in order to stabilize electrical contact. As the bonding auxiliary film, gold, platinum, nickel, or the like can be used. For example, after depositing 2 μm of nickel on the bonding surface 5a of the metal substrate 5 by plating, 1 μm of gold is deposited on the nickel.
Furthermore, a eutectic metal such as die bonding AuSn may be formed instead of the auxiliary bonding film. Thereby, a joining process can be simplified.

<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 epitaxy (Liquid Phase EpiLex) 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 biscyclopentadiethynylmagnesium ((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.
Etch stop layer 12b, at the time of the semiconductor substrate etched away until the cladding layer and the luminescent layer is a layer for preventing are etched, for example, the 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 5 formed in the manufacturing process of the metal substrate are carried into a decompression device. The joining surface 4a of the reflective structure 4 and the joining surface 5a of the metal substrate 5 are arranged so as to be opposed to each other.
Next, after evacuating 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 5 are heated to 400 ° C. 4a and the joining surface 5a of the metal substrate 5 are joined 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.

<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.

<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. For example, a metal layer structure made of AuGe / Ni / Au can be used as the electrode conductive film. 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.

Using the mask used in the patterning in the first electrode formation step, for example, a mixed solution of ammonia water (NH 4 OH) / hydrogen peroxide (H ₂ O ₂ ) / pure water (H ₂ 0) in the contact layer 12c. Thus, the portion other than under the n-type ohmic electrode (first electrode) 6 is removed by etching. 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 this, it is preferable to alloy each metal of the n-type ohmic electrode (first electrode) 6 by performing a 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 FIGS. 9A to 9C, a process of removing portions of the compound semiconductor layer and the front metal layer on the planned cutting line (front surface etching process) will be described.

<Compound semiconductor layer removal step>
First, as shown in FIG. 9A, a resist is applied on the compound semiconductor layer 3 of the wafer of light emitting diodes, 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 layer. 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.

<Front surface metal layer removal process>
Next, as shown in FIG. 9B, the wafer is immersed in 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 and removed. (Refer to 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%, ammonium fluoride 0.05-0.1%, A 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 portions of the Au layers 35 and 36 located below the removed portion are etched and removed (see reference numerals 35A and 36A). ).
Next, the wafer is immersed in a ferric chloride solution whose etching rate for Ni and Cu is higher than that for Mo and Ni and Cu can be selectively etched, and the removed portions of the Ni layer 37 and the Cu layer 21A are removed. The portion located below is removed by etching until the Mo layer 22 is exposed (see reference numerals 37A and 21AA).
By the above procedure, the compound semiconductor layer and the front metal layer on the cutting line can be removed.

<Back side metal layer removal step> (Back side etching step)
With reference to FIGS. 10A to 10C, a process of removing a portion of the back surface metal layer on the planned cutting line will be described.

First, as shown in FIG. 10A, a resist is applied on the Au / Ni layer formed on the metal substrate 5 on the back surface of the light emitting diode wafer, and includes a line pattern to be cut having a width of about 40 μm, for example, by photolithography. A resist pattern 41 is formed.

Next, as shown in FIG. 10B, the wafer is immersed in an Au-based etching solution, for example, a cyan-based etching solution, and the portion of the Au layer 42 located below the removed portion is etched and removed ( Part indicated by reference numeral 42A).

Next, as shown in FIG. 10C, the wafer is immersed in a ferric chloride solution in which the etching rate for Ni and Cu is higher than the etching rate for Mo and Ni and Cu can be selectively etched. A portion of 21B located below the removed portion is removed by etching until the Mo layer is exposed (portions indicated by reference numerals 43A and 21BB).
The back surface Cu layer on the cutting scheduled line is removed by the above procedure.

The compound semiconductor layer removal step, the front surface Cu layer removal step, and the back surface Cu layer removal step are all preferably performed. However, when laser irradiation is performed from the front surface, the compound semiconductor layer removal step and the back surface Cu layer removal step are performed. Even if it only performs, the bad influence of the heat generated at the time of laser cutting can be reduced.
Similarly, when laser irradiation is performed from the back surface, even if only the compound semiconductor layer removal step and the front Cu layer removal step are performed, the adverse effect of heat generated during laser cutting can be reduced.

When performing all the removal steps, the compound semiconductor layer removal step, the front surface metal layer removal step, and the back surface metal layer removal step may be performed in this order, or the compound after the back surface metal layer removal step is performed first. You may perform a semiconductor layer removal process and a front surface metal layer removal process in order. Moreover, it can also carry out in order of a compound semiconductor layer removal process, a back surface metal layer removal process, and a front surface metal layer removal process. The back surface metal layer removing step and the front surface metal layer removing step can be performed simultaneously.
However, when laser irradiation is performed from the front surface, it is convenient and preferable to perform the back surface metal layer removing step, the compound semiconductor layer removing step, and the front surface metal layer removing step in this order. On the other hand, when the laser irradiation is performed from the back surface, it is convenient and preferable to perform the compound semiconductor layer removal step, the front surface metal layer removal step, and the back surface metal layer removal step in this order.

<Laser dicing process>
For example, after all the removing steps are performed, the metal layer is cut by irradiating a laser along the portion where the metal layer on the line to be cut on the back surface is removed to cut the metal substrate.

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 multiple 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, 54 formed on the package substrate 55, and the electrode terminal 54. The light-emitting diode 1 includes a transparent resin (sealing resin) 51 made of silicon or the like formed so as to cover the light-emitting diode 1.
The light-emitting diode 1 includes the compound semiconductor layer 3, the reflective structure 4, the metal substrate 5, the first electrode 6, and the second electrode 8, and is arranged so that the metal substrate 5 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, the light emitting layer 2 can function as a heat sink, and the heat dissipation of the light emitting diode 1 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. 3 μm thick, GaP layer 2 μm, reflective structure Ag layer 0.7 μm, Ni / Ti barrier layer 0.5 μm, Au layer 1 μm, metal substrate Cu layer 10 μm / Mo layer 75 μm / Cu layer 10 μm A wafer having a Ni layer of 2 μm and an Au layer of 1 μm formed in order on both sides of the layer structure was produced.

On the front surface of this wafer, the Cu layer on the front surface side of the metal substrate was removed by etching to form a groove having a width of 60 μm. On the back surface, the Cu 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 Mo layer of the metal substrate was laser-cut from the front 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.
The debris was attached to the side surface of the Cu layer on the front surface side and the side surface of the Cu layer on the back surface side of the metal substrate, but the Cu layer on the front surface side and the Cu layer on the back surface side were exposed. No debris adhering to the surface was observed.

The present invention is particularly applicable to a manufacturing method, a cutting method, and an industry using a light emitting diode using a metal substrate as a substrate.

1 Light-emitting diode (light-emitting diode chip)
DESCRIPTION OF SYMBOLS 2 Light emitting layer 3 Compound semiconductor layer 4 Reflective structure 5 Metal substrate 14 Transparent conductive film 15 Metal bonding film 21 (21A, 21B) 1st metal layer 22 2nd metal layer 50 Light emitting diode lamp 55 Metal substrate

Claims (17)

1. In a method of manufacturing a chip-like light emitting diode by irradiating a laser on a wafer,
   Producing a wafer comprising a metal substrate composed of a plurality of metal layers, and a compound semiconductor layer including a light emitting layer formed on the metal substrate;
   Removing the portion of the compound semiconductor layer on the line to be cut by etching;
   A step of removing at least one layer on the opposite side of the laser irradiation surface of the plurality of metal layers on the line to be cut by etching;
   Irradiating a laser along the removed portion of the metal layer in plan view to cut the metal substrate;
   A method for producing a light emitting diode, comprising:
2. Before the step of cutting the metal substrate, the method further comprises the step of removing at least one layer on the laser irradiation surface side of the plurality of metal layers on the planned cutting line by etching. The manufacturing method of the light emitting diode of Claim 1.
3. The plurality of metal layers includes a material having a thermal expansion coefficient larger than that of the compound semiconductor layer and a material having a thermal expansion coefficient smaller than that of the compound semiconductor layer. Or the manufacturing method of the light emitting diode of 2.
4. The light emission according to claim 3, wherein the material having a thermal expansion coefficient larger than that of the compound semiconductor layer is made of any of aluminum, copper, silver, gold, nickel, titanium, or an alloy thereof. Diode manufacturing method.
5. 4. The method for manufacturing a light-emitting diode according to claim 3, 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.
6. The method of manufacturing a light emitting diode according to claim 1 or 2, wherein the plurality of metal layers are three metal layers.
7. The method of manufacturing a light emitting diode according to claim 6, wherein, of the three metal layers, two metal layers sandwiching one metal layer are made of the same metal material.
8. The method of manufacturing a light emitting diode according to claim 7, wherein the one metal layer is made of molybdenum, and the two metal layers are made of copper.
9. 7. The light-emitting diode according to claim 6, wherein, of the three metal layers, two metal layers sandwiching one metal layer are removed by etching, and the one metal layer is cut by a laser. Production method.
10. 3. The method of manufacturing a light emitting diode according to claim 1, wherein the light emitting layer includes an AlGaInP layer or an AlGaAs layer.
11. The method for producing a light-emitting diode according to claim 1, wherein a reflective structure is provided between the compound semiconductor layer and the metal substrate.
12. In a method of cutting a chip-shaped light emitting diode by irradiating a laser on a wafer including a metal substrate composed of a plurality of metal layers and a compound semiconductor layer formed on the metal substrate,
    Removing the portion of the compound semiconductor layer on the line to be cut by etching;
    A step of removing at least one layer on the opposite side of the laser irradiation surface of the plurality of metal layers on the line to be cut by etching;
    Irradiating a laser along the removed portion of the metal layer in plan view to cut the metal substrate;
    The cutting method characterized by having.
13. Before the step of cutting the metal substrate, the method further comprises the step of removing at least one layer on the laser irradiation surface side of the plurality of metal layers on the planned cutting line by etching. The cutting method according to claim 12.
14. A light-emitting diode manufactured by the method for manufacturing a light-emitting diode according to claim 1.
15. A light emitting diode comprising a metal substrate comprising a plurality of metal layers and a compound semiconductor layer including a light emitting layer formed on the metal substrate,
    The side surface of the metal substrate consists of a wet etching surface and a laser cutting surface arranged side by side in the thickness direction of the metal substrate,
    Of the plurality of metal layers, the side surface of at least one metal layer on the side of the compound semiconductor layer and the side surface of at least one metal layer on the opposite side of the compound semiconductor layer are wet etching surfaces,
    A by-product produced by laser irradiation adheres only to the side surface of the metal substrate.
16. The plurality of metal layers are three metal layers, the side surfaces of the two metal layers sandwiching one metal layer are the wet etched surface, and the side surfaces of the one metal layer are the laser cut surfaces. The light emitting diode according to claim 15.
17. The light emitting diode according to claim 16, wherein the one metal layer is made of molybdenum, and the two metal layers are made of copper.

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