JP2014007192A - Method for bonding led wafer, method for manufacturing led chip, and bonding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for bonding an LED wafer, a method for manufacturing an LED chip, and a bonding structure.SOLUTION: The method of bonding an LED wafer includes the following steps. A first metal thin film is formed on an LED wafer. A second metal thing film is formed on a substrate. A bonding material layer having a melting point of about 110°C or less is formed on a surface of the first metal thing film. The LED wafer is placed on the substrate. The bonding material layer is heated at a pre-solid reaction temperature for a pre-solid time to perform a pre-solid reaction. The bonding material layer is heated at a diffusion reaction temperature for a diffusing time to perform a diffusion reaction. The melting points of a first and a second inter-metallic compound layers after the diffusion reaction are higher than about 110°C.

Description

  The technical field relates to a method for bonding LED wafers, a method for manufacturing LED chips, and a bonding structure.

  Mainstream light emitting diode (LED) chips have three types of structures: a sapphire base structure, a flip-chip structure, and a vertical structure. For example, an LED having a sapphire base is described in US Pat. No. 7,566,908. Sapphire bases are characterized by excellent mechanical properties and low cost, and have become the mainstream gallium nitride (GaN) growth substrate.

  For LED chips having a vertical structure, the LED wafer and the thermally and electrically conductive materials are first bonded and then the sapphire base is lifted off using an excimer laser. . The LED chip having a vertical structure is characterized by high heat dissipation, high luminous efficiency, and no current clustering, and is a mainstream structure for high power LED chips.

  The present disclosure relates to a method for bonding LED wafers, a method for manufacturing LED chips, and a bonding structure.

  According to one embodiment, a method for bonding light emitting diode (LED) wafers is provided. The bonding method is a method of bonding an LED wafer and a substrate. The joining method includes the following steps. A first metal thin film is formed on the LED wafer. A second metal thin film is formed on the substrate. A bonding material layer is formed on the surface of the first metal thin film, and the melting point of the bonding material layer is about 110 ° C. or less. The LED wafer is placed on the substrate so that the bonding material layer can contact the second metal film. The bonding material layer is heated at a presolid reaction temperature for a pre-solid time to form a first intermetallic compound layer between the first metal thin film and the bonding material layer and a second A pre-solid reaction is performed in which a second intermetallic compound layer is formed between the metal thin film and the bonding material layer. The bonding material layer is heated at the diffusion reaction temperature for the diffusion time to perform the diffusion reaction, and the melting point of the first intermetallic compound layer and the second intermetallic compound layer after the diffusion reaction is higher than about 110 ° C.

  According to another embodiment, a method of manufacturing a light emitting diode (LED) chip is provided. The method of manufacturing the LED chip includes the following steps. A first metal thin film is formed on the LED wafer. A second metal thin film is formed on the substrate. A bonding material layer is formed on the surface of the first metal thin film, and the melting point of the bonding material layer is about 110 ° C. or less. The LED wafer is placed on the substrate so that the bonding material layer can contact the second metal film. The bonding material layer is heated at a presolid reaction temperature for a presolid time to form a first intermetallic compound layer between the first metal thin film and the bonding material layer and a second metal thin film and the bonding material layer. A pre-solid reaction is performed to form a second intermetallic compound layer between the two. The bonding material layer is heated at the diffusion reaction temperature for the diffusion time to perform the diffusion reaction, and the melting point of the first intermetallic compound layer and the second intermetallic compound layer after the diffusion reaction is higher than about 110 ° C. The base of the LED wafer is lifted off, and the LED wafer and substrate are singulated to form a plurality of LED chips.

  According to an alternative embodiment, a joint structure is provided. The bonding structure includes a substrate, a second metal thin film, a second intermetallic compound layer, a first intermetallic compound layer, a first metal thin film, and an LED wafer. A second metal thin film is disposed on the substrate. The material of the second metal thin film includes gold (Au), silver (Ag), copper (Cu), nickel (Ni), or a combination thereof. A second intermetallic compound layer is disposed on the second metal thin film. A first intermetallic compound layer is disposed on the second intermetallic compound layer. The materials of the first intermetallic compound layer and the second intermetallic compound layer are copper indium tin (Cu—In—Sn) intermetallic compound, nickel indium tin (Ni—In—Sn) intermetallic compound, nickel Bismuth (Ni-Bi) intermetallic compound, gold indium (Au-In) intermetallic compound, silver indium (Ag-In) intermetallic compound, silver tin (Ag-Sn) intermetallic compound, gold bismuth (Au-Bi) Including intermetallic compounds or combinations thereof. A first metal thin film is disposed on the first intermetallic compound layer. The material of the first metal thin film includes gold (Au), silver (Ag), copper (Cu), nickel (Ni), or a combination thereof. An LED wafer is disposed on the first metal thin film.

  The above and other aspects of the present disclosure will be better understood with regard to the following detailed description of non-limiting embodiment (s). The following description is made with reference to the accompanying drawings.

2 is a flow diagram of a method of bonding a light emitting diode (LED) wafer and a substrate and a method of manufacturing an LED chip, according to an embodiment of the present disclosure. It is a figure which shows the procedure of each step of FIG. It is a figure which shows the procedure of each step of FIG. It is a figure which shows the procedure of each step of FIG. It is a figure which shows the procedure of each step of FIG. It is a figure which shows the procedure of each step of FIG. It is a figure which shows the procedure of each step of FIG. It is a figure which shows the procedure of each step of FIG.

  In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

  Exemplary embodiments will now be described in detail with reference to the accompanying drawings, as will be readily understood by those skilled in the art. The concepts of the present invention can be embodied in various forms and are not limited to the exemplary embodiments described herein. For clarity, description of well-known parts has been omitted, and like reference numerals refer to like components throughout.

  Please refer to FIGS. FIG. 1 shows a flowchart of a method of bonding a light emitting diode (LED) wafer 110 and a substrate 170 and a method of manufacturing an LED chip 300 according to one embodiment of the present disclosure. 2 to 8 show the detailed procedure of each step in FIG.

  Steps S101 to S106 relate to a method of bonding the LED wafer 110 and the substrate 170. As shown in FIG. 7, after step S <b> 106 is completed, a bonding structure 200 for bonding the LED wafer 110 and the substrate 170 is formed.

  Steps S101 to S107 relate to a method for manufacturing the LED chip 300. As shown in FIG. 8, after step S107 is completed, a plurality of LED chips 300 are formed.

  Please refer to FIG. In step S <b> 101, the first metal thin film 120 is formed on the LED wafer 110. The LED wafer 110 includes, for example, a base, an N-type semiconductor layer, a luminous material layer, and a P-type semiconductor layer. The light emitting material layer is disposed between the N-type semiconductor layer and the P-type semiconductor layer, and forms a PIN structure. The base is, for example, a sapphire base. The materials of the N-type semiconductor layer and the P-type semiconductor layer are gallium nitride (GaN), gallium indium nitride (GaInN), aluminum indium gallium phosphide (AlInGaP), aluminum nitride (AlN), indium nitride (InN), and indium gallium nitride. Arsenic (InGaAsN), indium gallium phosphide (InGaPN), or a combination thereof. In one embodiment, the first metal film 120 can be formed on the surface of the LED wafer 110 opposite the base.

  The spectrum of light emitted from the LED wafer 110 is the spectrum of any visible light whose wavelength is in the range of 380 nanometers (nm) to 760 nanometers (nm) or in other wavelength ranges. It can be. Further, the LED wafer 110 can be realized by, for example, a sapphire base structure, a vertical structure, or a flip chip structure.

  The material of the first metal thin film 120 includes gold (Au), silver (Ag), copper (Cu), nickel (Ni), or a combination thereof. In this step, the first metal thin film 120 may be formed on the LED wafer 110 by electroplating, sputtering, or e-gun evaporation. Although the thickness of is not limited, For example, they are 0.1 micrometer (micrometer)-2.0 micrometers (micrometer). For example, the thickness of the first metal thin film 120 is in the range of 0.5 micrometers (μm) to 1.0 micrometers (μm).

  Referring to FIG. 3, a second metal thin film 160 is formed on the substrate 170 in step S102. The material of the substrate 170 is gold (Au), silver (Ag), copper (Cu), nickel (Ni), molybdenum (Mo), silicon (Si), silicon carbide (SiC), aluminum nitride (AlN), metal ceramic Including composite materials or combinations thereof.

  The material of the second metal thin film 160 includes gold (Au), silver (Ag), copper (Cu), nickel (Ni), or a combination thereof. In this step, the second metal thin film 160 can be formed on the substrate 170 by electroplating, sputtering, or vapor deposition. The thickness of the second metal thin film 160 is not limited, but is about 0.1, for example. Micrometer (μm) to 2.0 micrometers (μm). For example, the thickness of the second metal thin film 160 is in the range of about 0.5 micrometers (μm) to 1.0 micrometers (μm).

  Referring to FIG. 4, a bonding material layer 140 is formed on the surface of the first metal thin film 120 in step S103. The material of the bonding material layer 140 is bismuth indium (Bi-In), bismuth indium zinc (Bi-In-Zn), bismuth indium tin (Bi-In-Sn), bismuth indium tin zinc (Bi-In-Sn-Zn). Or a combination thereof. The melting point of the bonding material layer 140 is not limited, but is about 110 ° C. or less, for example. For example, the melting point of bismuth indium (Bi-In) is about 110 ° C., and the melting point of bismuth indium zinc (for example, Bi-25In-18Zn (Bi: In: Zn mass ratio is 1:25:18)). Is about 82 ° C., and the melting point of bismuth indium tin zinc (for example, Bi-20In-30Sn-3Zn (Bi: In: Sn: Zn mass ratio is 1: 20: 30: 3)) is about 90 ° C. The melting point of bismuth indium zinc (for example, Bi-33In-0.5Zn (Bi: In: Zn mass ratio is 1: 33: 0.5)) is about 110 ° C. In this step, the bonding material layer 140 can be formed on the first metal thin film 120 by electroplating, sputtering, or vapor deposition. The thickness of the bonding material layer 140 is not limited, but is about 0.2, for example. Micrometer (μm) to 5.0 micrometers (μm). For example, the thickness of the bonding material layer 140 is in the range of about 0.5 micrometers (μm) to 1.5 micrometers (μm).

  Please refer to FIG. The LED wafer 110 is disposed on the substrate 170 so that the bonding material layer 140 can come into contact with the second metal thin film 160.

  Referring to FIG. 6, in step S <b> 105, the bonding material layer 140 is heated at the presolid reaction temperature for a presolid time, and the first intermetallic compound layer 130 is interposed between the first metal thin film 120 and the bonding material layer 140. And a pre-solid reaction for forming a second intermetallic compound layer 150 between the second metal thin film 160 and the bonding material layer 140 is performed. The pre-solid reaction of this embodiment of the present disclosure can be realized by a liquid-solid reaction.

  The purpose of this step is to facilitate the subsequent processing by fixing the LED wafer 110 and the substrate 170 in advance according to the current alignment relation. The pre-solid reaction temperature can be equal to or higher than the melting point of the bonding material layer 140. For example, the pre-solid reaction temperature is about 80 ° C. or higher, or ranges from about 80 ° C. to 200 ° C. In one example, the pre-solid time is about 0.1 seconds to 10 minutes. In one example, the pre-solid time should be very short so that the positional relationship is effectively maintained so that unexpected effects such as thermo-stress do not occur on the LED wafer 110. Can do.

  When the material of the bonding material layer 140 is bismuth indium tin (Bi—In—Sn), the pre-solid reaction temperature can be about 82 ° C. or higher. The bonding material layer 140 may be heated by laser heating, thermal wind heating, infrared light heating, heat pressure heating, or ultra-sonic added thermal pressure heating. Heating can be accomplished by raising the ambient temperature to the pre-solid reaction temperature, heating the bonding material layer 140 directly, or heating the substrate 170 directly so that heat is transferred to the bonding material layer 140. Taking FIG. 6 as an example, the bottom surface of the substrate 170 is directly heated by a laser, and the pre-solid reaction temperature is about 85 ° C.

  The pre-solid time can be adjusted according to the situation of the pre-solid reaction. That is, the first intermetallic compound layer 130 having a sufficient size can be formed between the first metal thin film 120 and the bonding material layer 140. Furthermore, when the second intermetallic compound layer 150 having a sufficient size is formed between the second metal thin film 160 and the bonding material layer 140, the presolid reaction can be terminated. The time required is pre-solid time. In this step, the pre-solid reaction can be terminated immediately when the first intermetallic compound layer 130 and the second intermetallic compound layer 150 are still very thin. Alternatively, the pre-solid reaction can be terminated before the first intermetallic compound layer 130 and the second intermetallic compound layer 150 are thicker.

The materials of the first intermetallic compound layer 130 and the second intermetallic compound layer 150 are determined according to the materials of the first metal thin film 120, the bonding material layer 140, and the second metal thin film 160. The materials of the first intermetallic compound layer 130 and the second intermetallic compound layer 150 are copper indium tin (Cu—In—Sn) intermetallic compounds (for example, CU ₆ In ₅ or Cu ₆ Sn ₅ ), Nickel indium tin (Ni-In-Sn) intermetallic compound, nickel bismuth (Ni-Bi) intermetallic compound, gold indium (Au-In) intermetallic compound, silver indium (Ag-In) intermetallic compound (for example, Ag ₂ In or AgIn ₂ ), silver tin (Ag—Sn) intermetallic compound (eg, Ag ₃ Sn), gold bismuth (Au—Bi) intermetallic compound (eg, Au ₂ Bi), gold tin (Au—Sn) Intermetallic compounds (eg, AuSn ₄ ) or combinations thereof are included.

  Referring to FIG. 7, in step S106, the bonding material layer 140 is heated at the diffusion reaction temperature for the diffusion time to execute the diffusion reaction. The diffusion reaction can be realized by a liquid-solid reaction or a solid-solid reaction. When the diffusion reaction is a liquid-solid reaction, the diffusion reaction temperature can be higher than the melting point of the bonding material layer 140. For example, when the diffusion reaction temperature is in the range of about 80 ° C. to 200 ° C., the diffusion time is about 0.5 hours to 3 hours.

  When the diffusion reaction is a solid-solid reaction, the diffusion reaction temperature is lower than the melting point of the bonding material layer 140. Since the diffusion reaction temperature is lower than the melting point of the bonding material layer 140, the diffusion reaction in this step has no influence on the positional relationship after the pre-solid reaction. For example, the diffusion reaction temperature is in the range of about 40 ° C. to 80 ° C., and the diffusion time is about 0.5 hours to 3 hours.

  When the diffusion reaction is a liquid-solid reaction, the diffusion reaction temperature is higher than the melting point of the bonding material layer 140. Since the diffusion reaction temperature is higher than the melting point of the bonding material layer 140, the diffusion reaction in this step aligns the LED wafer 110 and the substrate 170 in order to improve the accuracy in positioning the LED wafer 110 and the substrate 170. Can be included.

  The diffusion reaction in this step can be adjusted according to the setting of the diffusion reaction temperature. The higher the diffusion reaction temperature, the shorter the diffusion time, and the lower the diffusion reaction temperature, the longer. In this embodiment of the present disclosure, the diffusion time is, for example, about 0.5 hours to 3 hours.

  Due to the diffusion reaction in this step, the alloying elements of the bonding material layer 140, the first metal thin film 120, and the second metal thin film 160 can diffuse to each other. The diffusion time can be set to a time required for most of the alloy elements of the bonding material layer 140 to be diffused. That is, this step can be executed until the diffusion reaction is completed.

  This step can employ batch processing such as temperature air heating, oven heating, infrared light heating or thermal plate heating.

After the diffusion reaction, the melting points of the first intermetallic compound layer 130 and the second intermetallic compound layer 150 are higher than about 110 ° C., for example. If the first intermetallic compound layer 130 and the second intermetallic compound layer 150 are formed from different materials, the melting points will be different accordingly. For example, the melting point of silver indium (Ag—In) intermetallic compound (eg, Ag ₂ In or AgIn ₂ ) is at least higher than 250 ° C., and silver tin (Ag—Sn) intermetallic compound (eg, Ag ₃ Sn). The melting point is higher than at least 450 ° C., the melting point of the gold bismuth (Au—Bi) intermetallic compound is higher than at least 350 ° C., and the melting point of the gold tin (Au—Sn) intermetallic compound is higher than at least 250 ° C.

  After the diffusion reaction, a portion of the bonding material layer 140 may form a first intermetallic compound layer 130 and a second intermetallic compound layer 150 to form an intermediate layer 140 ′ (as shown in FIG. 7). May be left between. In one embodiment, the bonding material layer 140 may completely react and disappear. The material of the intermediate layer 140 ′ includes tin (Sn), bismuth (Bi), indium (In), zinc (Zn), or a combination thereof.

  Taking FIG. 7 as an example, after steps S101 to S106 are completed, the bonding structure 200 for bonding the LED wafer 110 and the substrate 170 is completed in this way. The bonding structure 200 includes a substrate 170, a second metal thin film 160, a second intermetallic compound layer 150, an intermediate layer 140 ′, a first intermetallic compound layer 130, and a first metal thin film 120. LED wafer 110. A second metal thin film 160 is disposed on the substrate 170. The second intermetallic compound layer 150 is disposed on the second metal thin film 160. An intermediate layer 140 ′ is disposed on the second intermetallic compound layer 150. A first intermetallic compound layer 130 is disposed on the intermediate layer 140 '. The first metal thin film 120 is disposed on the first intermetallic compound layer 130. An LED wafer 110 is disposed on the first metal thin film 120.

  Referring to FIG. 8, in step S107, the base of the LED wafer 110 is lifted off, and the LED wafer 110 and the substrate 170 are cut into individual pieces to form a plurality of LED chips 300. This step further includes electrode processing, point testing, classification and the like. Finally, a plurality of LED chips 300 are formed.

  Embodiments of the present disclosure provide a method for bonding an LED wafer 110, a method for manufacturing an LED chip 300, and a bonding structure for bonding an LED wafer 110 and a substrate 170. The LED wafer 110 is bonded at a low temperature (eg, about 110 ° C. or less), thus avoiding thermal stress problems that arise due to differences in the coefficients of thermal expansion. In this embodiment, the bonding process does not require high pressure, high flatness, or a protective atmosphere.

  In the present embodiment, the bonding material layer 140 is a metal, and the melting point of the first intermetallic compound layer 130 and the second intermetallic compound layer 150 after the diffusion reaction and the temperature of the intermediate layer 140 ′ are about 250 ° C. It can be raised to be higher. The LED wafer 110, the LED chip 300, and the bonding structure 200 of the present disclosure have low bonding thermal stress, high dissipation performance, high bonding strength, and high heat resistance.

In the present embodiment, the first metal thin film 120 containing Ag can be sputtered on a base having a diameter of 2 inches and a thickness of 650 μm. Thereafter, a Bi thin film having a thickness of 500 nm, an In thin film having a thickness of 500 nm, and a Sn thin film having a thickness of 1500 nm are deposited on the first metal thin film 120 by electron beam evaporation. Next, the base is bonded to the substrate 170 by a bonding station such as an Electron Visions EV501 Bonding Station. The material of the substrate 170 includes silicon, and the thickness of the substrate 170 is 500 μm. An Ag thin film having a thickness of 200 nm is sputtered on the substrate 170. In the first stage (pre-solid reaction stage), the base and the substrate are heated at 170 ° C. for 5 minutes and pressed with a force of 10N. In the second stage (diffusion reaction stage), the base and substrate 170 are heated at 170 ° C. for 30 minutes and pressed with a force of 3000 N. After these two stages, Ag ₂ In, AgIn ₂ , and Ag ₃ Sn can be observed with an electron microscope. In this embodiment, the Bi thin film, the In thin film, and the Sn thin film are not limited to being deposited in that order.

  It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiment. It is intended that the detailed description and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.

Claims (14)

A method of bonding a light emitting diode (LED) wafer and a substrate, the bonding method comprising:
Forming a first metal thin film on the LED wafer;
Forming a second metal thin film on the substrate;
Forming a bonding material layer on the surface of the first metal thin film, the bonding material layer has a melting point of 110 ° C. or less;
Placing the LED wafer on the substrate to allow the bonding material layer to contact the second metal thin film;
The bonding material layer is heated at a presolid reaction temperature for a presolid time to form a first intermetallic compound layer between the first metal thin film and the bonding material layer, and the second metal thin film; Performing a pre-solid reaction to form a second intermetallic compound layer with the bonding material layer;
The bonding material layer is heated at a diffusion reaction temperature for a diffusion time to execute a diffusion reaction, and the melting point of the first intermetallic compound layer and the second intermetallic compound layer after the diffusion reaction is higher than 110 ° C. ,
A method of bonding a light emitting diode (LED) wafer and a substrate.   The method for bonding LED wafers according to claim 1, wherein the pre-solid reaction temperature is 80 ° C. to 200 ° C., and the pre-solid time is 0.1 second to 10 minutes.   The method for bonding LED wafers according to claim 1, wherein the diffusion time is 0.5 hours to 3 hours.   The method of bonding LED wafers according to claim 1, wherein the diffusion reaction temperature is 80 ° C. to 200 ° C.   The method of bonding an LED wafer according to claim 1, wherein the material of the first metal thin film includes gold (Au), silver (Ag), copper (Cu), nickel (Ni), or a combination thereof.   The material of the bonding material layer is bismuth indium (Bi-In), bismuth indium zinc (Bi-In-Zn), bismuth indium tin (Bi-In-Sn), bismuth indium tin zinc (Bi-In-Sn-Zn). Or a combination thereof, the method of bonding LED wafers according to claim 1.   The materials of the first intermetallic compound layer and the second intermetallic compound layer are copper indium tin (Cu—In—Sn) intermetallic compound and nickel indium tin (Ni—In—Sn) intermetallic compound. , Nickel bismuth (Ni-Bi) intermetallic compound, gold indium (Au-In) intermetallic compound, silver indium (Ag-In) intermetallic compound, silver tin (Ag-Sn) intermetallic compound, gold bismuth (Au- The method for bonding LED wafers according to claim 1, comprising Bi) an intermetallic compound, a gold tin (Au-Sn) intermetallic compound, or a combination thereof.   The method for bonding LED wafers according to claim 1, wherein the bonding material layer has a thickness of 0.2 μm to 5.0 μm. A method of manufacturing a light emitting diode (LED) chip, comprising:
A method of bonding the LED wafer according to claim 1;
Lifting off the base of the LED wafer and cutting the LED wafer and the substrate into pieces, forming a plurality of LED chips, lifting off and cutting;
A method of manufacturing a light emitting diode (LED) chip. A joining structure,
A substrate,
A second metal thin film disposed on the substrate;
A second intermetallic compound layer disposed on the second metal thin film;
A first intermetallic compound layer disposed on the second intermetallic compound layer, wherein each material of the first intermetallic compound layer and the second intermetallic compound layer is copper indium tin (Cu-In-Sn) intermetallic compound, nickel indium tin (Ni-In-Sn) intermetallic compound, nickel bismuth (Ni-Bi) intermetallic compound, gold indium (Au-In) intermetallic compound, silver indium ( Ag-In) intermetallic compound, silver tin (Ag-Sn) intermetallic compound, gold bismuth (Au-Bi) intermetallic compound, gold tin (Au-Sn) intermetallic compound, or a combination thereof, a first An intermetallic compound layer;
A first metal thin film disposed on the first intermetallic compound layer;
An LED wafer disposed on the first metal thin film;
Including junction structure. 11. The junction structure according to claim 10, wherein each material of the first intermetallic compound layer and the second intermetallic compound layer contains Ag ₂ In, AgIn _2, or Ag ₃ Sn.   It further includes an intermediate layer interposed between the first intermetallic compound layer and the second intermetallic compound layer, and the material of the intermediate layer is tin (Sn), bismuth (Bi), indium (In) And zinc (Zn) or a combination thereof.   The bonding structure according to claim 10, wherein the material of the second metal thin film includes gold (Au), silver (Ag), copper (Cu), nickel (Ni), or a combination thereof.   The bonding structure according to claim 10, wherein the material of the first metal thin film includes gold (Au), silver (Ag), copper (Cu), nickel (Ni), or a combination thereof.

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