JP6519407B2 - Light emitting device and method of manufacturing light emitting device - Google Patents

Description

  The present disclosure relates to a light emitting device including a light emitting element and a method of manufacturing the light emitting device.

  In a light emitting device on which a light emitting element such as an LED (light emitting diode) is mounted, an inexpensive material is required for a member used for the light emitting device in order to make the light emitting device inexpensive. For this reason, the wiring pattern of the mounting substrate is particularly inexpensive as compared with Cu or the like as a material of the wiring pattern of the flexible substrate, and Al which is light in weight and excellent in flexibility may be used.

  On the other hand, as a method of mounting a light emitting element such as an LED on a mounting substrate, the electrodes of the light emitting element and the wiring pattern of the mounting substrate are opposed to each other via an anisotropic conductive adhesive and thermocompression bonded. There is a method of bonding and electrical connection (see, for example, Patent Document 1).

An anisotropic conductive adhesive is provided with anisotropic conductivity by dispersing conductive particles in an insulating binder resin. The conductive particles are formed by providing a metal coating such as Au on the surface of a resin core having elasticity.
By using such an anisotropic conductive adhesive for mounting a light emitting element, bonding can be performed at a low temperature as compared with the case of using solder or the like.

JP, 2011-57917, A

  However, since the anisotropic conductive adhesive contains a binder resin, its thermal conductivity is relatively low, and it is difficult to sufficiently dissipate the heat generated from the light emitting element to the mounting substrate side. In the light emitting element, when the temperature of the active layer is 100 ° C. or more in particular, the luminous efficiency is significantly reduced, the lifetime is shortened, and the reliability is reduced. Therefore, it is important to efficiently dissipate the heat generated by the light emitting element.

Then, the manufacturing method of the light-emitting device concerning embodiment of this indication makes it a subject to be able to reduce the thermal resistance between a mounting substrate and a light emitting element, and to provide the manufacturing method which manufactures a cheap light-emitting device.
Another object of the present invention is to provide a highly reliable light emitting device that is inexpensive and in which the thermal resistance between the mounting substrate and the light emitting element is reduced.

  A method of manufacturing a light emitting device according to an embodiment of the present disclosure is a method of manufacturing a light emitting device including a light emitting element and a mounting substrate provided with a wiring pattern for mounting the light emitting element, and an electrode of the light emitting element The light emitting element and the mounting are thermocompression-bonded by sandwiching an anisotropic conductive bonding member containing conductive particles and Sn-based solder particles containing no Au in the composition between the above and the wiring pattern. The electrode includes an Au-containing layer on the side facing the wiring pattern, and the surface of the wiring pattern contains Al as a main component, and the Au bonding is performed by the thermocompression bonding. An Au—Sn based alloy layer connecting the electrode and the wiring pattern is formed by the containing layer and the solder particle.

A light emitting device according to an embodiment of the present disclosure includes a light emitting element, a mounting substrate including a wiring pattern for mounting the light emitting element, and an anisotropic conductive bonding member for bonding the light emitting element and the mounting substrate. And the surface of the wiring pattern is mainly made of Al, and the anisotropic conductive bonding member is an electrode of the light emitting element between the electrode of the light emitting element and the wiring pattern and the wiring pattern has a Au-Sn alloy layer that connects the door, have a solder particles of Sn system containing no Au in a portion other than between the wiring pattern and electrodes of the light emitting element, the electrodes of the light emitting element , at least in a partial region of the wiring pattern and the surface facing the side, configured to have a Au-containing layer is high Au content than the alloy layer.

According to the method of manufacturing a light emitting device according to the embodiment of the present disclosure, it is possible to manufacture an inexpensive and highly reliable light emitting device.
Moreover, according to the light emitting device according to the embodiment of the present disclosure, the light emitting device can be inexpensive and highly reliable.

It is a sectional view showing typically the composition of the light emitting device concerning an embodiment. It is sectional drawing which shows typically the structure of the electroconductive particle contained in the anisotropic conductive joining member used for the light-emitting device which concerns on embodiment. The light-emitting device which concerns on embodiment WHEREIN: It is sectional drawing which shows typically the example of the structure of an alloy layer. The light-emitting device which concerns on embodiment WHEREIN: It is sectional drawing which shows typically the other example of the structure of an alloy layer. It is sectional drawing which shows typically the structure of the light emitting element used for the light-emitting device which concerns on embodiment. It is a phase diagram of Au-Sn type alloy. It is a flowchart which shows the procedure of the manufacturing method of the light-emitting device which concerns on embodiment. In the manufacturing method of the light emitting device concerning an embodiment, it is a sectional view showing typically a joining member arrangement process. In the manufacturing method of the light emitting device concerning an embodiment, it is a sectional view showing typically the light emitting element mounting process. In the manufacturing method of the light-emitting device which concerns on embodiment, it is sectional drawing which shows typically a thermocompression-bonding process.

  Hereinafter, a light emitting device and a method of manufacturing the light emitting device according to the embodiment will be described with reference to the drawings. Note that the sizes, positional relationships, and the like of members shown in each drawing may be exaggerated for the sake of clarity. Further, in the following description, the same names and reference numerals indicate the same or the same members in principle, and the detailed description will be appropriately omitted.

Embodiment
[Configuration of light emitting device]
The light emitting device according to the present embodiment includes at least a light emitting element, a mounting substrate provided with a wiring pattern for mounting the light emitting element, and an anisotropic conductive bonding member for bonding the light emitting element and the mounting substrate. And the anisotropic conductive joint member has an Au-Sn alloy layer between the electrode of the light emitting element and the wiring pattern, and other than between the electrode of the light emitting element and the wiring pattern The Sn-based solder particles have a lower proportion of Au than the alloy layer or no Au in the part of.

Anisotropic conduction that connects Au to the outside of the electrode of the light emitting element, which is a stable material resistant to oxidation or deterioration, and using inexpensive Al for the wiring pattern of the mounting substrate When lead-free Sn-based solder with little adverse effect on the environment is used as solder contained in the joining member, Au, which is an electrode on the light-emitting element side, and Sn-based solder form an alloy well and solder bond. Since Al forms an oxide film on the surface of Al and Sn-based solder on the mounting substrate side, it is generally difficult to perform solder bonding. Therefore, when Al is used for the wiring pattern of the mounting substrate, even if the anisotropic conductive bonding member contains solder, the thermal resistance between the solder and the wiring pattern of the mounting substrate is sufficiently lowered. There is a problem that you can not do it.
Therefore, as in the present embodiment, the Au-containing layer of the electrode of the light emitting element and the Sn-based solder particles contained in the anisotropic conductive bonding member form an alloy layer, whereby the electrode of the light emitting element and the mounting substrate The thermal resistance between the wiring pattern and the wiring pattern can be reduced, the heat dissipation can be improved, and the temperature rise of the light emitting element can be suppressed. Thus, the light emitting device can have high reliability.

The configuration of the light emitting device according to the present embodiment will be described with reference to FIGS. 1A to 2B.
In FIG. 1A, the light emitting element 1 is shown with a detailed structure omitted, but as shown in FIG. 3, the n-side electrode 13 is electrically connected to the n-type semiconductor layer 12 n of the semiconductor stack 12, The p-side electrode 15 is electrically connected to the p-type semiconductor layer 12 p via the entire surface electrode 14. The same applies to the light emitting element 1 shown in FIGS. 6A to 6C described later.
Moreover, FIG. 2A and FIG. 2B expand and show the joining state by the alloy layer 34 formed between the n side electrode 13 and the wiring pattern 22. As shown in FIG. The bonding state by the alloy layer 34 formed between the p-side electrode 15 and the wiring pattern 22 is similar to this.

The light emitting device 100 is configured such that the light emitting element 1 is flip chip mounted on the mounting substrate 2 using the anisotropic conductive bonding member 3. The number of light emitting elements 1 mounted on the mounting substrate 2 is not limited to one, and may be two or more.
The respective components will be sequentially described in detail below.

The light emitting element 1 has an n-side electrode 13 and a p-side electrode 15 which are a pair of electrodes on the lower surface side, and is flip-chip mounted on the upper surface of the mounting substrate 2 using the anisotropic conductive bonding member 3.
Here, a configuration example of the light emitting element 1 will be described with reference to FIG. In FIG. 3, the light emitting element 1 is shown upside down as the light emitting element 1 flip-chip mounted in the light emitting device 100 shown in FIG. 1A for the convenience of description. That is, the surface on which the n-side electrode 13 and the p-side electrode 15 are provided is shown to be upward.

  The light emitting element 1 can use suitably semiconductor light emitting elements, such as LED. The light emitting element 1 in the present embodiment is configured to include a substrate 11, a semiconductor laminate 12, an n-side electrode 13, an entire surface electrode 14, a p-side electrode 15, and a protective film 16. In addition, the light emitting element 1 in the present embodiment includes the semiconductor stacked body 12 on one main surface of the substrate 11, and further includes the n-side electrode 13 and the p-side electrode 15 on the semiconductor stacked body 12; It has a structure suitable for implementation.

  The substrate 11 is a member that supports the semiconductor stack 12. As a specific material, sapphire, SiC or the like can be used. For example, when the semiconductor stacked body 12 is formed using a nitride semiconductor such as GaN (gallium nitride), sapphire can be suitably used as the substrate 11.

The semiconductor laminate 12 is formed by laminating an n-type semiconductor layer 12 n, an active layer 12 a and a p-type semiconductor layer 12 p on one main surface which is the upper surface of the substrate 11. It is configured to emit light by supplying a current to the
The semiconductor stack 12 has a region where the p-type semiconductor layer 12p and the active layer 12a are not partially present, that is, a region 12b where the n-type semiconductor layer 12n is exposed. An n-side electrode 13 is provided in a region 12b where the n-type semiconductor layer 12n is exposed, and is electrically connected to the n-type semiconductor layer 12n.
In addition, the entire surface electrode 14 is provided on substantially the entire top surface of the p-type semiconductor layer 12 p, and the p-side electrode 15 is provided on a part of the top surface of the full surface electrode 14.

  The n-side electrode 13 is a pad electrode on the negative electrode side for supplying a current from the outside to the light emitting element 1. In the present embodiment, the n-side electrode 13 has a multilayer structure in which the first layer 13a and the second layer 13b are stacked.

The first layer 13a is an adhesion layer for bringing the n-side electrode 13 and the n-type semiconductor layer 12n into close contact with each other, and Ni, Ti, Pt or the like can be suitably used. The first layer 13a may be formed by laminating the above-described metal materials. In the case of laminating a metal material, for example, Ni (20 nm) / Ti (200 nm), Ti (200 nm) / Pt (300 nm), etc. can be sequentially provided from the n-type semiconductor layer 12 n side. In addition, the first layer 13a may be a single layer, or three or more layers may be stacked.
It is preferable that these metal materials do not form an alloy with the solder particles 33.

The second layer 13 b is provided on the outermost surface of the n-side electrode 13, and is electrically connected to the wiring pattern 22 via the conductive particles 32 contained in the anisotropic conductive bonding member 3. It is a layer made of Au. The Au content of the second layer 13 b is preferably 99% by mass or more, and the Au content is more preferably 100% by mass except for the impurities contained unavoidably. The film thickness of the second layer 13 b is preferably about 300 nm or more. As a result, the Sn-based solder particles 33 contained in the anisotropic conductive bonding member 3 are melted by heating to a relatively low temperature (for example, about 260 ° C. or less) to form a homogeneous alloy layer 34. Can. For example, the solder particles 33 and the alloy layer 34 having a relatively low melting point (for example, about 230 ° C. or less) having a composition in which the Au content is 2% by mass or more and 12% by mass or less can be used.
It should be noted that another layer may be provided on the surface of the second layer 13 b as long as the material and thickness do not inhibit the formation of the alloy layer 34 by the second layer 13 b and the solder particles 33.

The entire surface electrode 14 is provided to cover substantially the entire surface of the upper surface of the p-type semiconductor layer 12p, and the current supplied from the outside through the p-side electrode 15 which is a pad electrode is the entire surface of the p-type semiconductor layer 12p. Function as a current diffusion layer for diffusion into the In addition, when a material having high light reflectivity is used for the entire surface electrode 14, the light emitted from the light emitting element 1 is reflected in the direction (upward in FIG. 1A) of the substrate 11 of the light emitting element 1 which is a light extraction surface. It can also function as a reflective film.
The entire surface electrode 14 can be made of a metal material having good conductivity and light reflectivity. In particular, as a metal material having good light reflectivity in the visible light region, Ag, Al, or an alloy containing any of these metals as a main component can be used in a single layer or stacked layers.

The p-side electrode 15 is a pad electrode provided on a part of the upper surface of the full-surface electrode 14 and connected to an external electrode. The p-side electrode 15 is configured by laminating a first layer 15 a and a second layer 15 b. The first layer 15a is made of a material having good ohmic properties and adhesion to the entire electrode 14 and the second layer 15b, and the second layer 15b is made of Au.
In the present embodiment, the first layer 15a and the second layer 15b of the p-side electrode 15 have the same configuration as the first layer 13a and the second layer 13b of the n-side electrode 13 described above, respectively. Detailed description will be omitted because there is one. The configurations of the p-side electrode 15 and the n-side electrode 13 may be different from each other. For example, the film thickness and the material may be different.

The protective film 16 is a film which has translucency and insulating properties and covers substantially the entire top and side surfaces of the light emitting element 1 except for the side and bottom surfaces of the substrate 11. The protective film 16 also has an opening on the upper surface of the n-side electrode 13 and the upper surface of the p-side electrode 15 which are regions for connection to the outside. As the protective film 16, for example, oxides such as SiO ₂ , TiO ₂ , and Al ₂ O ₃ , nitrides such as SiN, and fluorides such as MgF ₂ can be suitably used.

  In the light emitting element 1, the arrangement region, the shape, the layer structure, and the like of the n-side electrode 13 and the p-side electrode 15 are not limited to the present embodiment, and can be determined appropriately.

Referring back to FIGS. 1A to 2B, the description of the configuration of the light emitting device 100 according to the present embodiment will be continued.
The mounting substrate 2 is a substrate on which electronic components such as the light emitting element 1 are mounted, and includes, for example, a plate-like or film-like base 21 and a wiring pattern 22 provided on the upper surface of the base 21.

The base 21 is preferably made of an insulating material, and is preferably made of a material that hardly transmits light emitted from the light emitting element 1 or external light. Moreover, it is preferable to use a material having a certain degree of strength. Specifically, resins such as ceramics (Al ₂ O ₃ , AlN, etc.), phenol resins, epoxy resins, polyimide resins, BT resins (bismaleimide triazine resin), polyphthalamide (PPA) and the like can be mentioned. The upper surface of the base 21 preferably has good light reflectivity at least in the region where the light emitting element 1 is mounted and the periphery thereof. For example, a metal such as Ag or Al or a white resin containing a white pigment is preferable. It is preferable to provide the light reflection layer used.

In the present embodiment, since the anisotropic conductive bonding member 3 is used, the light emitting element 1 can be mounted on the mounting substrate 2 at a relatively low temperature. For this reason, as a material of the base 21, a resin material having low heat resistance compared to ceramics or the like, for example, a polyimide resin can be used.
When the mounting substrate 2 is a flexible substrate, the base 21 preferably has flexibility. As a specific material, polyimide resin, polyethylene terephthalate resin, epoxy resin or the like can be used. The thickness of the base 21 in this case can be, for example, about 50 μm to 500 μm.

The wiring pattern 22 has bonding regions corresponding to the electrodes of the respective polarities in order to bond to the n-side electrode 13 and the p-side electrode 15 of the light emitting element 1.
In the present embodiment, Al, which is suitable as the wiring of the flexible substrate and is relatively inexpensive, is used as the wiring pattern 22.

The anisotropic conductive bonding member 3 is an adhesive formed by dispersing the conductive particles 32 and the Sn-based solder particles 33 in the resin 31, and applies (pressurizes) a load from above at the time of mounting, and further heats it. By doing this, the light emitting element 1 and the mounting substrate 2 are bonded (thermocompression bonding). As the anisotropic conductive bonding member 3, any form of paste-like ACP (anisotropic conductive paste) or film-like ACF (anisotropic conductive film) can be used. In addition, the anisotropic conductive bonding member 3 can be adjusted to an appropriate viscosity by adjusting the amount of the solvent and the addition amount of the filler such as SiO ₂ .

  In the anisotropic conductive bonding member 3 having anisotropy, conductive particles 32 are formed between the wiring pattern 22 of the mounting substrate 2 and the n-side electrode 13 and the p-side electrode 15 of the light emitting element 1 in the longitudinal direction Electrical connection is made in the direction perpendicular to the mounting surface which is the connection surface. On the other hand, in the lateral direction (direction parallel to the mounting surface) between the wiring patterns 22 of the mounting substrate 2 and between the n-side electrode 13 and the p-side electrode 15 of the light emitting element 1, the conductive particles 32 are mutually different. An appropriate amount of conductive particles 32 is dispersed in the resin 31 so as not to be in continuous contact.

  The resin 31 is used as a binder of various particles and a bonding material for obtaining the adhesive strength between the light emitting element 1 and the mounting substrate 2. The resin 31 preferably has translucency and is excellent in light resistance and heat resistance. When the resin 31 is a thermosetting resin, the curing temperature is preferably about 250 ° C. or less, and when the resin is a thermoplastic resin, the melting point is preferably about 250 ° C. or less. As such a resin material, for example, a resin material such as silicone resin, silicone modified resin, epoxy resin, epoxy modified resin, urea resin, phenol resin, acrylic resin, or hybrid resin containing one or more of these resins is used. be able to. Among them, silicone resins or epoxy resins are preferable, and in particular, silicone resins excellent in light resistance and heat resistance are more preferable.

The conductive particles 32 are composed of a core member 32a made of an insulating material such as a resin and having a spherical shape and elasticity, and a metal film 32b covering the surface of the core member 32a. The conductive particles 32 are not limited to this, and may have other configurations.
For example, resin materials such as epoxy resin, phenol resin, acrylic resin, AS (acrylonitrile styrene) resin, benzoguanamine resin, divinylbenzene resin, and styrene resin can be used as the core member 32a. Such a resin material is suitably used as the core member 32a of the conductive particles 32, but since the thermal resistance of the material is higher than that of the metal, when joining with only the conductive particles 32, the light emitting element 1 to the mounting substrate 2 It is difficult to improve the heat dissipation of Therefore, as in the present embodiment, the light emitting element 1 and the mounting substrate are formed by forming the alloy layer 34 by the solder particles 33 and the second layers 13 b and 15 b which are Au-containing layers of the electrodes 13 and 15 of the light emitting element 1. The thermal resistance between 2 and 2 can be reduced.
As the metal film 32b, metal materials such as Au, Ni, Zn and the like can be suitably used.
The particle diameter (D50) of the conductive particles 32 is preferably, for example, about 1 μm to 10 μm, and more preferably about 2 μm to 6 μm. The content of the conductive particles 32 is preferably about 1% by volume to 30% by volume with respect to the resin 31 as a binder.

The solder particles 33 are particles made of Sn-based solder, and by mainly bonding the n-side electrode 13 and the p-side electrode 15 of the light emitting element 1 and the wiring pattern 22 of the mounting substrate 2, Is contained in the anisotropic conductive joint member 3 in order to reduce the thermal resistance. As Sn-based solder, for example, Sn-based lead-free solder specified in JIS Z 3282: 2006 can be suitably used. A specific material of the solder particle 33 is Sn, and in addition, there is a Sn-based solder containing Zn, Sb, In, Ag, Bi, and Cu and having a Pb content of 0.10 mass% or less.
The content of the solder particles 33 is preferably about 1% by volume or more and 30% by volume or less with respect to the resin 31. By setting the content of the solder particles 33 to 1% by volume or more, thermal resistance can be effectively reduced by joining the n-side electrode 13 and the p-side electrode 15 to the wiring pattern 22. Further, by setting the content of the solder particles 33 to about 30% by volume or less, even if the conductive solder particles 33 are contained, the anisotropic conductive bonding member 3 maintains the aforementioned anisotropy. it can.

  The particle diameter (D50) of the solder particles 33 is preferably about 1 μm to 25 μm, and more preferably about 4 μm to 10 μm. The particle diameter of the solder particles 33 is preferably about 85% to 120% of the particle diameter of the conductive particles 32. By setting the particle diameter of the solder particles 33 in this range, the conductive particles 32 become flat between the n-side electrode 13 and the p-side electrode 15 of the light emitting element 1 and the wiring pattern 22 when performing thermocompression bonding. While being deformed, the solder particles 33 can sufficiently contact the n-side electrode 13 and the p-side electrode 15. As a result, the solder particles 33 and the Au constituting the second layers 13b and 15b of the n-side electrode 13 and the p-side electrode 15 can be melted to easily form an alloy.

  As described above, the second layers 13 b and 15 b on the mounting surface side of the n-side electrode 13 and the p-side electrode 15 of the light emitting element 1 are configured using Au. In addition, since the second layers 13b and 15b are formed to have a film thickness (for example, 300 nm) equal to or greater than a predetermined thickness, as shown in FIG. 2A, the light emitting element 1 is formed using the anisotropic conductive bonding member 3. The Au of the second layers 13 b and 15 b and the Sn-based solder particles 33 contained in the anisotropic conductive bonding member 3 melt when the thermocompression bonding of the chip and the mounting substrate 2 is performed, and the Au having a substantially homogeneous composition An alloy layer 34 mainly composed of a Sn alloy is formed. The solder particles 33 do not form a solder bond with the wiring pattern 22 made of Al, but are formed so that the alloy layer 34 of Au and the solder particles 33 adheres closely to the wiring pattern 22. With such a configuration, the alloy layer 34 connects the n-side electrode 13 and the p-side electrode 15 to the wiring pattern 22 of the mounting substrate 2 to form a heat conduction path. The thermal resistance to the mounting substrate 2 can be reduced. In order to effectively reduce the thermal resistance, the alloy layer 34 is preferably provided as wide as possible, for example, 50% or more of the planar area of the p-side electrode 15 and the n-side electrode 13, and more preferably 70. It is preferable to provide in the size of% or more, more preferably 80% or more. The alloy layer 34 having such a wide planar area can be formed by pressing the solder particles 33 in the thermocompression bonding and laterally spreading it.

  If the film thickness of Au in the second layers 13 b and 15 b is too thin, the Au and the Sn-based solder are not sufficiently alloyed, and are formed between the n-side electrode 13 and the p-side electrode 15 and the wiring pattern 22. In the bonding layer to be formed, grain boundaries in which Au and Sn-based solder are separated from each other are formed. The bonding layer having such grain boundaries has a lower thermal conductivity than the alloy layer 34 which is a completely melted bonding layer, but increases the portion where heat is conducted from the light emitting element 1 to the wiring pattern 22 of Al. Can reduce the thermal resistance somewhat.

Here, the composition of the alloy layer 34 is preferably a eutectic composition (Au: 10% by mass) having a melting point of 217 ° C., which is the eutectic temperature on the low temperature side of the Au—Sn based alloy. As shown in the phase diagram of FIG. 4, the melting point of the alloy can be set to about 230 ° C. or less by setting the composition of the alloy to about 2 mass% to 12 mass% of Au. By this, an alloy can be formed between Au and Sn-based solder by heating to a low temperature (for example, about 260 ° C. or less) by thermocompression bonding. Thus, a material having relatively low heat resistance such as PET can be used as the material of the light emitting device 100 (for example, the material of the base 21).
The solder particle 33 may be any one as long as Au and Sn can form the alloy layer 34, and the proportion of Sn may be 100%, and in addition to Sn, a material other than Au may be slightly (for example, 5 mass% or less) may be contained. For example, other metals such as In, Zn, Sb, Ag, Bi, and Cu may be included.

  Also, as shown in FIG. 2B, when the film thickness of the second layer 13b, which is an Au-containing layer, is large, the Au on the surface side of the second layer 13b and the solder particles 33 melt and an alloy having a homogeneous composition. The layer 34 can be formed, and the Au-containing layer can be left between the alloy layer 34 and the semiconductor laminate 12. Therefore, the thermal resistance between the n-side electrode 13 and the p-side electrode 15 and the wiring pattern 22 can be sufficiently reduced. Therefore, the upper limit of the film thickness of the second layer 13b is not particularly limited, and can be determined in consideration of mass productivity such as electrode material cost and throughput of electrode formation. Although the second layer 13 b of the n-side electrode 13 is shown as an example here, the same applies to the second layer 15 b of the p-side electrode 15.

  For bonding the light emitting element 1 and the mounting substrate 2, as described above, an Au—Sn alloy having high thermal conductivity is preferably used. However, the Au-Sn based alloy material generally has a higher light absorptivity as compared to Sn containing no Au. Therefore, as in the light emitting device 100 according to the present embodiment, Sn-based solder particles are mixed in the anisotropic conductive bonding member 3, and the solder particles and the electrodes 13 and 15 of the light emitting element 1 are provided. By forming an Au-Sn alloy with Au of the second layers 13 b and 15 b and joining the light emitting element 1 and the mounting substrate 2, the solder particles 33 of the Au-Sn alloy can be joined to the anisotropic conductive joint member 3. The absorption by the anisotropic conductive bonding member 3 of the light emitted from the light emitting element 1 can be reduced compared to the case where the light emitting element 1 is contained in the whole. Thereby, the light emission efficiency of the light emitting device 100 can be enhanced.

In addition, the anisotropic conductive joint member 3 may further contain particles of a light reflective material. Thus, the light propagating to the mounting surface side of the light emitting element 1 can be reflected in the light extraction direction, and the light extraction efficiency can be improved.
As the light reflective material, for example, TiO ₂ (titanium oxide), ZrO ₂ (zirconium oxide), MgO (magnesium oxide), Al ₂ O ₃ (aluminum oxide) or the like can be used. Further, the particle diameter of the light diffusing substance particles is such that the conductive particles 32 and the solder particles 33 can be well contacted to the n-side electrode 13 and the p-side electrode 15 and the wiring pattern 22 at the time of thermocompression bonding. And preferably smaller than these particles.

[Operation of light emitting device]
Next, the operation of the light emitting device 100 will be described with reference to FIG. 1A, FIG. 1B and FIG.
By connecting an external power supply to the wiring pattern 22 of the mounting substrate 2, power is supplied to the light emitting element 1 mainly through the conductive particles 32 of the anisotropic conductive bonding member 3 to emit light. The light emitted upward from the light emitting element 1 is mainly extracted to the outside from the substrate 11 side.
In addition, the heat generated with the light emission of the light emitting element 1 is efficiently transmitted to the mounting substrate 2 side through the Au—Sn alloy layer 34 continuous with the first layers 13 a and 15 a of the electrodes of the light emitting element 1. As a result, the temperature rise of the light emitting element 1 is suppressed.

[Method of manufacturing light emitting device]
Next, a method of manufacturing the light emitting device according to the present embodiment will be described with reference to FIGS. 5 to 6C. The method of manufacturing a light emitting device according to the present embodiment includes a light emitting element preparation step S101, a mounting substrate preparation step S102, and a bonding step S103.
Further, the bonding step S103 includes, as sub-steps, a bonding member arranging step S103a, a light emitting element mounting step S103b, and a thermocompression bonding step S103c.

  The light emitting element preparation step S101 is a step of preparing the singulated light emitting element 1 having the configuration as shown in FIG. Hereinafter, an example of steps of manufacturing the light emitting element 1 by the wafer level process will be described, but the present invention is not limited thereto.

  Specifically, first, an n-type semiconductor layer 12n, an active layer 12a, and a p-type semiconductor layer 12p are sequentially stacked on a substrate 11 of sapphire or the like using a semiconductor material such as a nitride semiconductor by MOCVD or the like. The semiconductor laminate 12 is formed. Thereafter, the p-type semiconductor layer 12p is subjected to a p-type annealing treatment. Next, with respect to a partial region of the surface of the semiconductor multilayer body 12, the whole of the p-type semiconductor layer 12p and the active layer 12a and the part of the n-type semiconductor layer 12n are removed by etching from the top surface side 12n form a bottom exposed area 12b.

  Thereafter, the entire surface electrode 14 is formed by sputtering or the like using a metal material such as Ag or Al so as to cover substantially the entire top surface of the p-type semiconductor layer 12p. Furthermore, the first layer 15a is formed on a part of the upper surface of the entire surface electrode 14 by sputtering or the like using a metal material such as Ni or Ti, and the second layer 15b is further laminated using Au. An electrode 15 is formed. Further, in the region 12b, the first layer 13a and the second layer 13b are stacked on the upper surface of the n-type semiconductor layer 12n in the same manner as the first layer 15a and the second layer 15b of the p-side electrode 15 by sputtering or the like. By doing this, the n-side electrode 13 is formed. Either of the n-side electrode 13 and the p-side electrode 15 may be formed first, and when the same material is used, they may be formed in the same process.

Next, a transparent insulating material such as SiO ₂ is used to form a wafer by sputtering or the like so as to have an opening in a region for connection to the outside of the upper surface of n-side electrode 13 and p-side electrode 15. A protective film 16 is formed to cover the whole.
The n-side electrode 13, the full-surface electrode 14, the p-side electrode 15, and the protective film 16 can be formed into a mask of an appropriate shape by photolithography, and can be patterned by an etching method or liftoff method using the mask. .

  Next, the light emitting element 1 is singulated by cutting the wafer using a dicing method or a scribing method.

The mounting substrate preparation step S102 is a step of preparing the mounting substrate 2 in which the wiring pattern 22 using Al is formed on the upper surface of the insulating base 21. The wiring pattern 22 is formed by forming a metal film on the entire upper surface of the base 21, providing a mask covering a region left as a wiring pattern on the metal film, and forming the exposed metal film by etching, using a subtractive method. It can be formed. In addition, the wiring pattern 22 is an additive method in which a mask is provided on the upper surface of the base 21 to cover the area not provided with the pattern, and a metal film is formed on the area where the upper surface of the base 21 is exposed. It can also be formed by
Note that any of the light emitting element preparation step S101 and the mounting substrate preparation step S102 may be performed first, or may be performed in parallel.

  The bonding step S103 is a step of flip-chip mounting the light emitting element 1 on the mounting substrate 2 using the anisotropic conductive bonding member 3. As mentioned above, this process includes three sub-steps.

First, as shown in FIG. 6A, in the joining member disposing step S103a, the anisotropic conductive joining member 3 is placed in the region where the light emitting element 1 is to be disposed on the upper surface of the mounting substrate 2 by potting method or printing method. Deploy.
The anisotropic conductive bonding member 3 used in the present embodiment is configured by containing conductive particles 32 and Sn-based solder particles 33 in a resin 31.

  Next, as shown in FIG. 6B, in the light emitting element mounting step S103b, the n side electrode 13 and the p side electrode 15 are placed at predetermined positions on the top surface of the mounting substrate 2 using, for example, a collet. Are placed via the anisotropic conductive bonding member 3 so as to face the wiring patterns 22 of the corresponding polarities.

Next, as shown in FIG. 6C, in the thermocompression bonding step S103c, for example, a load is applied from the upper surface side of the light emitting element 1 using a thermocompression bonding apparatus, thereby pressure bonding the light emitting element 1 and the mounting substrate 2 Thus, the conductive particles 32 sandwiched between the n-side electrode 13 and the p-side electrode 15 and the wiring pattern 22 are flatly deformed. Thus, the conductive particles 32 can be brought into close contact with the n-side electrode 13, the p-side electrode 15 and the wiring pattern 22 to be electrically connected.
The application of the load may be performed from the upper surface side of the light emitting element 1 or may be performed from the lower surface side of the mounting substrate 2. Further, a load may be applied from both the upper surface side of the light emitting element 1 and the lower surface side of the mounting substrate 2.
Furthermore, the light emitting element 1 and the mounting substrate 2 are bonded by heating the anisotropic conductive bonding member 3 and curing the resin 31 while maintaining the pressure-bonded state.

Resins, phosphors, and the like used as members constituting light emitting devices often have relatively low heat resistance. For this reason, in order to widen the choice of the material which can be used, it is preferable to make heating temperature in the case of thermocompression bonding into about 260 degrees C or less. Therefore, these materials are selected so that the curing temperature of the resin 31 and the melting point of the alloy layer 34 of the solder particles 33 and Au become lower than the heating temperature.
As described above, in the case of pressing and heating from both the upper surface side of the light emitting element 1 and the lower surface side of the mounting substrate 2, the heating temperature is the same on the upper surface side of the light emitting element 1 and the lower surface side of the mounting substrate 2 It may be present or different. For example, in the case of using a resin having low heat resistance as the material of the mounting substrate 2, the deterioration of the mounting substrate 2 due to heat is reduced by setting the heating temperature from the mounting substrate 2 lower than the temperature of the light emitting element 1. can do.

  In addition, during heating, the Sn-based solder particles 33 sandwiched between the n-side electrode 13 and the p-side electrode 15 and the wiring pattern 22 are the second layer 13 b or p of the n-side electrode 13 in contact. It melts with Au of the second layer 15 b of the side electrode 15 to form an alloy layer 34 having a homogeneous composition. The alloy layer 34 having a homogeneous composition is continuously formed between the first layers 13 a and 15 a of the electrodes of the light emitting element 1 and the wiring pattern 22, whereby the n-side electrode 13, the p-side electrode 15 and the wiring pattern 22 are formed. The thermal resistance between and is reduced.

  Next, as necessary, a light-transmissive sealing member for covering the surfaces of the light-emitting element 1 and the mounting substrate 2 is provided. When a resin is used as the material of the sealing member, the sealing member may be deteriorated by the heat emitted from the light emitting element 1 and the light transmittance may be reduced, whereby the output of the light emitting device may be reduced. . However, in the present embodiment, since the heat from the light emitting element 1 can be efficiently dissipated to the mounting substrate 2, the deterioration of the sealing member due to the heat can be reduced. Thus, the light emitting device can have high reliability.

  By performing the above steps, the light emitting device 100 is manufactured.

  In order to confirm the effect of the manufacturing method of the light emitting device according to the present embodiment, using a light emitting element manufactured by changing the film thickness of the Au-containing layer which is the second layer of the n-side electrode and the p-side electrode The light-emitting device joined to the wiring pattern of Al of a mounting substrate was manufactured using the anisotropic conductive joint member containing the solder particle of these. Then, the thermal resistance between the n-side electrode and the p-side electrode and the wiring pattern was measured.

[Manufacturing conditions]
(Example)
· Film thickness of second layer (Au-containing layer: 100% by mass of Au content): 300 nm
(Comparative example)
· Film thickness of second layer (Au-containing layer: 100% by mass of Au content): 50 nm
(Common to Examples and Comparative Examples):
First layer: Ti (200 nm) / Pt (300 nm)
-Composition of solder particles: Sn: 96.5% by mass, Ag: 3% by mass, Cu: 0.5% by mass
· Solder particle size: 5 μm
-Material of wiring pattern: Al

[Measurement result of thermal resistance]
The thermal resistance value of the measured junction (between the second layer and the wiring pattern) is shown below.
The thermal resistance value is determined by transient heat measurement in accordance with the JESD 51-14 standard of JEDEC (Joint Electron Device Engineering Council). This measurement method is a method of calculating a temperature change from the voltage change based on the correlation between the junction temperature of the device such as a light emitting element and the voltage.
(Example): 8 [° C / W]
(Comparative example): 16 [° C./W]
The smaller this value is, the lower the thermal resistance is. When this thermal resistance value is converted by the temperature rise rate of the light emitting element per 1 W of the power consumption of the light emitting element, the comparative example rises by 16 ° C. The example shows an 8 ° C. rise. That is, when the same power consumption is applied to the light emitting element, this junction suppresses the temperature rise to half.

  As described above, according to the present embodiment, it has been confirmed that the temperature increase rate can be suppressed to about half that of the comparative example, in other words, the thermal resistance can be reduced to about half.

  As mentioned above, although the manufacturing method of the light-emitting device concerning the present invention was concretely explained by the form for carrying out the invention, the meaning of the present invention is not limited to these descriptions, and the statement of a claim is described. It should be interpreted broadly based on Further, it is needless to say that various changes and modifications based on these descriptions are included in the spirit of the present invention.

  The light emitting device manufactured in the embodiment of the present disclosure includes a backlight light source of a liquid crystal display, various lighting fixtures, a large display, various display devices such as advertisement and destination guidance, and a digital video camera, a facsimile, a copier, and a scanner. And the like, and can be used for various light sources such as an image reading apparatus and a projector apparatus.

DESCRIPTION OF SYMBOLS 1 light emitting element 11 board | substrate 12 semiconductor laminated body 12 n n-type semiconductor layer 12a active layer 12p p-type semiconductor layer 12b area | region where n-type semiconductor layer exposed 13 n side electrode 1st layer of 13 an n side electrode 13 b n side electrode 2nd Layer (Au-containing layer)
14 full surface electrode 15 p side electrode 15 a first layer of p side electrode 15 b second layer of p side electrode (Au-containing layer)
Reference Signs List 16 protective film 2 mounting substrate 21 base 22 wiring pattern 3 anisotropic conductive bonding member 31 resin 32 conductive particle 32 a core member 32 b metal film 33 solder particle 34 alloy layer 100 light emitting device

Claims (10)

A method of manufacturing a light emitting device, comprising: a light emitting element; and a mounting substrate including a wiring pattern for mounting the light emitting element,
Between the electrode of the light emitting element and the wiring pattern, thermocompression bonding is performed by sandwiching an anisotropic conductive bonding member containing conductive particles and Sn-based solder particles not containing Au in the composition. Including a bonding step of bonding the light emitting element and the mounting substrate,
The electrode has an Au-containing layer on the side facing the wiring pattern,
The surface of the wiring pattern is mainly made of Al,
The manufacturing method of the light emitting device which forms the Au-Sn type alloy layer which connects the said electrode and the said wiring pattern with the said Au containing layer and the said solder particle by the said thermocompression bonding.   The method for manufacturing a light emitting device according to claim 1, wherein the composition of the alloy layer is 2% by mass or more and 12% by mass or less of Au.   The light emission according to claim 1 or 2, wherein in the thermocompression bonding, the contact portion between the electrode and the solder particle is heated to 217 ° C. or higher, which is the eutectic temperature of the low temperature side of the Au-Sn alloy. Device manufacturing method.   The method for manufacturing a light emitting device according to any one of claims 1 to 3, wherein in the thermocompression bonding, the electrode and the solder particle are heated to a temperature of 260 ° C or less.   The method for manufacturing a light emitting device according to any one of claims 1 to 4, wherein the Au-containing layer has a thickness of 300 nm or more.   The method for manufacturing a light emitting device according to claim 5, wherein the solder particles have a particle diameter of 1 μm to 25 μm.   The method for manufacturing a light emitting device according to any one of claims 1 to 6, wherein a particle diameter of the solder particle is 85% or more and 120% or less of a particle diameter of the conductive particle.   The method for manufacturing a light emitting device according to any one of claims 1 to 7, wherein the mounting substrate is a flexible substrate.   The method for manufacturing a light emitting device according to any one of claims 1 to 8, wherein the solder particles are lead-free solder defined in JIS Z 3282: 2006. A light emitting element,
A mounting substrate comprising a wiring pattern for mounting the light emitting element;
And an anisotropic conductive bonding member for bonding the light emitting element and the mounting substrate,
The surface of the wiring pattern is mainly made of Al,
The anisotropic conductive bonding member has an Au-Sn based alloy layer connecting an electrode of the light emitting element and the wiring pattern between an electrode of the light emitting element and the wiring pattern, and the light emitting element have a solder particles of Sn system containing no Au in a portion other than between the electrode and the wiring pattern,
The electrode of the light-emitting element, at least in a partial region of the wiring pattern and the surface facing the side, Au content to have a high Au-containing layer than the alloy layer, the light emitting device.

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