CN101212008A - Electroluminescent device and method for manufacturing the same - Google Patents

Abstract

An electroluminescent device comprises a heat-conducting substrate, a heat-conducting bonding layer, a heat-conducting insulating layer, a reflecting layer, a light-emitting diode element, a first contact electrode and a second contact electrode. The heat conduction bonding layer is arranged on the heat conduction substrate, the heat conduction insulating layer is arranged on the heat conduction bonding layer, the reflecting layer is arranged on the heat conduction insulating layer, and the light emitting diode element is arranged on the reflecting layer and exposes part of the reflecting layer. The first contact electrode is disposed on the light emitting diode element, and the second contact electrode is disposed on the exposed portion of the reflective layer. A method of making an electroluminescent device is also disclosed.

Description

Electroluminescence device and manufacturing method thereof

technical field

The invention relates to a light-emitting device and a manufacturing method thereof, in particular to an electroluminescence device and a manufacturing method thereof.

Background technique

In recent years, due to the progress of electroluminescence (electroluminescence) technology, the materials and process technology of light emitting diode (light emitting diode, LED) have also been continuously improved, and its application scope covers indicator lights of computers or home appliances, liquid crystal The backlight of display devices, traffic signals or car indicator lights may even have the opportunity to be used as light sources for lighting in the future. However, as the luminous power of the LEDs continues to increase, the heat generated by them also increases. If the heat energy of the LEDs cannot be effectively treated, the luminous efficiency of the LEDs will be reduced.

An existing light-emitting diode is formed by a secondary attachment process, and the steps include: growing an epitaxial layer on a temporary substrate; transferring the epitaxial layer to a glass substrate, and removing the temporary substrate; coating a specular reflection layer on the on the epitaxial layer; and pasting the epitaxial layer on the permanent substrate, and removing the glass substrate.

Based on the above, please refer to FIG. 1A , the LED 1 formed according to the above steps structurally includes a permanent substrate 11 , an organic adhesive layer 12 , a specular reflection layer 13 and an epitaxial layer 14 .

The epitaxial layer 14 has a p-type doping 141 , a light-emitting layer 142 and an n-type doping 143 . In addition, a p-type electrode 151 is disposed on the p-type doping 141 , and an n-type electrode 152 is disposed on the n-type doping 143 . The material of the organic adhesive layer 12 is generally PR, epoxy resin (Epoxy), polyimide quartz (Polyimide-Quartz), FR-4 type epoxy resin, Teflon (Teflon), polyimide (polyimide) , benzocyclobutene (BCB) or fluorocyclobutane (PFCB), and its thermal conductivity is usually between 0.1 (W/mk) and 0.3 (W/mk), so it is important for the thermal energy treatment of light-emitting diode 1 has a rather high degree of difficulty. In addition, when the permanent substrate 11 is metal, since there is no insulation protection between the permanent substrate 11 and the epitaxial layer 14 , it is easy to cause a short circuit between the two.

In addition, as shown in FIG. 1B , another existing LED 2 has a metal reflective layer 22 , a co-metallic adhesive layer 23 , a transparent conductive layer 24 and an epitaxial layer 25 on a permanent substrate 21 in sequence. The epitaxial layer 25 has p-type doping 251, light-emitting layer 252 and n-type doping 253 in sequence, wherein n-type doping 253 is in contact with part of the transparent conductive layer 24, and an n-type electrode 261 , and a p-type electrode 262 is disposed on the p-type doped 251 .

The co-gold adhesive layer 23 is formed by two metal layers 231 , 232 by hot pressing process, so as to enhance the bonding ability with the transparent conductive layer 24 and the metal reflective layer 22 respectively. However, the temperature required by the co-metallurgy process is generally higher than 300-400° C., which will also affect the epitaxial layer 25 to a certain extent and reduce its luminous efficiency.

Therefore, how to provide an electroluminescent device with a good heat dissipation path to eliminate the heat energy generated by the electroluminescent device and reduce its temperature, thereby improving the luminous efficiency and its manufacturing method is one of the current important issues.

Contents of the invention

Therefore, in order to solve the above problems, the present invention proposes an electroluminescent device with a good heat dissipation path to improve luminous efficiency and a manufacturing method thereof.

According to the purpose of the present invention, an electroluminescent device is proposed, which includes a thermally conductive adhesive layer, a thermally conductive substrate, a reflective layer, a light emitting diode element, a first contact electrode and a second contact electrode. The thermally conductive substrate is arranged on one side of the thermally conductive adhesive layer; the reflective layer is arranged on the other side of the thermally conductive adhesive layer; the light-emitting diode element is arranged on the reflective layer, and part of the reflective layer is exposed, wherein the light-emitting diode element has first A semiconductor layer, a light-emitting layer and a second semiconductor layer, the second semiconductor layer is in contact with the reflective layer; the first contact electrode is electrically connected to the first semiconductor layer; the second contact electrode is located at the exposed part of the reflective layer and is electrically connected to the reflective layer.

The above-mentioned electroluminescent device, when the material of the heat-conducting substrate is a conductive material, may further include a heat-conducting insulating layer, which may be arranged between the reflective layer and the heat-conducting bonding layer, or between the heat-conducting bonding layer and the heat-conducting substrate In order to avoid short-circuit between the light-emitting diode element and the heat-conducting substrate and cause failure.

According to another object of the present invention, a method for manufacturing an electroluminescent device is proposed, comprising the following steps: forming a light-emitting diode element on a board, wherein the light-emitting diode element sequentially includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer , and the first semiconductor layer is formed on the plate body; forming a reflective layer on the LED element; disposing the thermally conductive adhesive layer on the reflective layer; disposing the thermally conductive substrate on the thermally conductive adhesive layer; and removing the plate body .

The above-mentioned manufacturing method of the electroluminescent device may also include disposing a heat-conducting insulating layer between the reflective layer and the heat-conducting adhesive layer, or disposing a heat-conducting insulating layer between the heat-conducting adhesive layer and the heat-conducting substrate, so as to prevent the light-emitting diode element from The heat-conducting substrate is short-circuited and fails.

In addition, in the aforementioned electroluminescent device and its manufacturing method, the material of the thermally conductive substrate can be selected from silicon, gallium arsenide, gallium phosphide, silicon carbide, boron nitride, aluminum, aluminum nitride, copper and combinations thereof group. The material of the thermally conductive adhesive layer can be solder paste, tin-silver paste, silver paste, or joint solder composed of other alloys. The material of the thermally conductive insulating layer can be aluminum nitride or silicon carbide.

Based on the above, according to an electroluminescent device and its manufacturing method of the present invention, a thermally conductive adhesive layer, a thermally conductive substrate, or even a thermally conductive insulating layer with high thermal conductivity is used to effectively conduct the heat energy generated by the light emitting diode element to the outside world to improve the luminous efficiency of the electroluminescent device.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, the preferred embodiments are specifically cited below, and in conjunction with the accompanying drawings, the detailed description is as follows:

Description of drawings

FIG. 1A is a schematic diagram showing a conventional light-emitting diode;

FIG. 1B is a schematic diagram showing another existing light-emitting diode;

2 is a flow chart showing a method of manufacturing an electroluminescent device according to a first embodiment of the present invention;

3A to 3I are respective schematic diagrams of electroluminescent devices according to the steps of the flowchart of FIG. 2;

4 is a flow chart showing a method of manufacturing an electroluminescent device according to a second embodiment of the present invention; and

5A to 5I are respective schematic diagrams of an electroluminescent device according to the steps of the flowchart of FIG. 4 .

simple notation

1, 2: LED

11, 21: permanent substrate

12: Organic adhesive layer

13: Specular reflection layer

14, 25: epitaxial layer

141, 251: p-type doped layer

142, 252: luminous layer

143, 253: n-type doped layer

151, 261: p-type electrode

152, 262: n-type electrode

22: Metal reflective layer

23: Co-gold adhesion layer

231, 232: metal layer

24: transparent conductive layer

3, 4: Electroluminescence device

31, 41: board body

32, 42: LED components

321, 421: the first semiconductor layer

322, 422: luminescent layer

323, 423: the second semiconductor layer

33, 43: reflective layer

34, 45: thermal insulation layer

35, 44: thermally conductive adhesive layer

36, 46: Thermally conductive substrate

37, 47: contact electrodes

371, 471: first contact electrodes

372, 472: second contact electrodes

S01～S09, S11～S19: process steps

Detailed ways

Embodiments of the electroluminescent device and its manufacturing method according to the present invention will be described below with reference to the relevant drawings.

First of all, an electroluminescent device and a manufacturing method thereof of the present invention will be described with the first embodiment and the second embodiment respectively. In addition, in this embodiment, the electroluminescence device is an example of a light emitting diode.

Referring to FIG. 2 , the method for manufacturing an electroluminescent device according to the first embodiment of the present invention includes steps S01 to S09 . Please refer to FIG. 3A to FIG. 3I at the same time. FIG. 3A to FIG. 3I are schematic diagrams of the electroluminescent device according to the steps of the flow chart in FIG. 2 . The electroluminescent device 3 and its manufacturing method according to the first embodiment of the present invention will be described in detail below.

As shown in FIG. 3A , step S01 forms the LED element 32 on the board body 31 . The plate body 31 can be a plate body for epitaxy, and its surface needs to be cleaned with acetone and ethanol before use, then cleaned with pure water, and then blown dry with nitrogen (N ₂ ). In addition, the light emitting diode element 32 sequentially includes a first semiconductor layer 321 , a light emitting layer 322 and a second semiconductor layer 323 , wherein the first semiconductor layer 321 is formed on the board body 31 . In this embodiment, the first semiconductor layer 321 is an n-type doped layer, and the second semiconductor layer 323 is a p-type doped layer.

As shown in FIG. 3B , step S02 forms a reflective layer 33 on the LED element 32 . Specifically, the reflective layer 33 is formed on the second semiconductor layer 323 of the LED element 32 . In this embodiment, the reflective layer 33 can be an ohmic contact metal reflective layer, which not only can be used to reflect the light emitted by the LED element 32, but also can make the current distribution more uniform due to its low resistance. In addition, the material of the reflective layer 33 can be selected from platinum (Pt), gold (Au), silver (Ag), palladium (Pd), nickel (Ni), chromium (Cr), titanium (Ti) and combinations thereof. Group.

As shown in FIG. 3C , step S03 forms a thermally conductive insulating layer 34 on the reflective layer 33 . In this embodiment, the thermally conductive insulating layer 34 can be formed on the reflective layer 33 by a reactive sputtering method, a non-reactive sputtering method, or a high temperature nitriding method. In addition, the material of the thermally conductive insulating layer 34 can be aluminum nitride (AlN) or silicon carbide (SiC), wherein the thermal conductivity of aluminum nitride is about 200-230 (W/mk), and the thermal conductivity of silicon carbide is about 300 ~490(W/mk).

As shown in FIG. 3D , step S04 disposes the thermally conductive adhesive layer 35 on the thermally conductive insulating layer 34 , that is, the thermally conductive adhesive layer 35 may not be in contact with the reflective layer 33 . Alternatively, the thermally conductive adhesive layer 35 may be in direct contact with the reflective layer 33 without the thermally conductive insulating layer 34 . Here, since the thermally conductive insulating layer 34 has been formed on the reflective layer 33 , the thermally conductive adhesive layer 35 is formed on the thermally conductive insulating layer 34 by screen printing, spin coating or dispensing. Wherein, the material of the thermally conductive adhesive layer 35 is solder paste, tin-silver paste, silver paste, or joint solder composed of other alloys.

As shown in FIG. 3E , step S05 disposes the thermally conductive substrate 36 on the thermally conductive adhesive layer 35 , that is, the thermally conductive substrate 36 may be in contact with the thermally conductive adhesive layer 35 or not. Here, since the thermally conductive adhesive layer 35 is formed on the thermally conductive insulating layer 34 , the thermally conductive substrate 36 is directly attached to the thermally conductive adhesive layer 35 . Wherein, the material of the thermally conductive substrate 36 may be selected from the group consisting of silicon, gallium arsenide, gallium phosphide, silicon carbide, boron nitride, aluminum, aluminum nitride, copper and combinations thereof.

It should be noted that the thermally conductive adhesive layer 35 can also be formed on the thermally conductive substrate 36 by screen printing, spin coating or dispensing, and then pasted with the thermally conductive insulating layer 34 , and the process sequence is not limited here.

As shown in FIG. 3F , step S06 turns over the electroluminescent device 3 formed in the above steps. As shown in FIG. 3G , step S07 removes the board body 31 , which can be removed by a laser lift-off process to remove the board body 31 .

As shown in FIG. 3H , step S08 removes part of the LED element 32 to expose part of the reflective layer 33 . In this embodiment, removing part of the LED element 32 by etching is taken as an example. Specifically, the step of removing part of the LED element 32 includes: forming a photoresist layer on the second semiconductor layer 323; irradiating the photoresist with light such as ultraviolet light (UV) through a mask layer; remove part of the photoresist layer to form a patterned photoresist layer; remove part of the second semiconductor layer 323, part of the light emitting layer 322 and part of the first semiconductor layer 321; and remove The patterned photoresist layer is removed to expose part of the reflective layer 33 . It is worth mentioning that the photoresist layer can be a photoresist layer with a positive photoresist coefficient or a photoresist layer with a negative photoresist coefficient. The difference is that after the light is irradiated, the part of the photoresist that is irradiated by light is removed or the part of the photoresist that is not irradiated by light is removed. However, this is a mature etching technology and will not be repeated here.

Finally, the step of forming the contact electrode 37, as shown in FIG. 3I, step S09 forms the first contact electrode 371 on part of the first semiconductor layer 321, and forms the second contact electrode 372 on the exposed portion of the reflective layer 33, To form an electroluminescent device 3 .

In this embodiment, the above-mentioned process can be completed at a process temperature between 25° C. and 300° C., so it belongs to a low-temperature process and is less likely to affect the yield of the LED element 32 . In addition, it is worth mentioning that when the material of the thermally conductive substrate 36 is an insulating material, the thermally conductive insulating layer 34 does not need to be provided, so the above-mentioned steps of forming the thermally conductive insulating layer 34 can be omitted.

Hereinafter, please refer to FIG. 4 , the electroluminescence device 4 and the manufacturing method thereof according to the second embodiment of the present invention include steps S11 to S19 . Please refer to FIG. 5A to FIG. 5I at the same time. FIG. 5A to FIG. 5I are schematic diagrams of the electroluminescent device according to the steps of the flow chart in FIG. 4 . The electroluminescent device 4 and its manufacturing method according to the second embodiment of the present invention will be described in detail below.

Please refer to FIG. 5A and FIG. 5B , step S11 and step S12 are the same as step S01 and step S02 in the first embodiment, so they will not be repeated here. That is, step S11 forms the LED element 42 on the board body 41 , and the LED element 42 sequentially includes a first semiconductor layer 421 , a light emitting layer 422 and a second semiconductor layer 423 , wherein the first semiconductor layer 421 is formed on the board body 41 . Step S12 forms a reflective layer 43 on the LED element 42 .

Next, as shown in FIG. 5C , step S13 disposes the thermally conductive adhesive layer 44 on the reflective layer 43 , that is, the thermally conductive adhesive layer 44 may be in contact with the reflective layer 43 or not in contact with the reflective layer 33 . Here, the thermally conductive adhesive layer 44 is formed on the reflective layer 43 by screen printing, spin coating or dispensing. Wherein, the material of the thermally conductive adhesive layer 44 is solder paste, tin-silver paste, silver paste, or joint solder composed of other alloys.

As shown in FIG. 5D , step S14 forms a thermally conductive insulating layer 45 on the thermally conductive substrate 46 . In this embodiment, the thermally conductive insulating layer 45 can be formed on the thermally conductive substrate 46 by a reactive sputtering method, a non-reactive sputtering method, or a high temperature nitriding method. In addition, the material of the thermally conductive insulating layer 45 can be aluminum nitride (AlN) or silicon carbide (SiC), wherein the thermal conductivity of aluminum nitride is about 200-230 (W/mk), and the thermal conductivity of silicon carbide is about 300 ~490(W/mk). In addition, the material of the thermally conductive substrate 46 may be selected from the group consisting of silicon, gallium arsenide, gallium phosphide, silicon carbide, boron nitride, aluminum, aluminum nitride, copper, and combinations thereof.

As shown in FIG. 5E , step S15 contacts the thermally conductive insulating layer 45 with the thermally conductive adhesive layer 44 , so that the thermally conductive substrate 46 and the thermally conductive insulating layer 45 are pasted on the reflective layer 43 .

It should be noted that the thermally conductive adhesive layer 44 can also be formed on the thermally conductive insulating layer 45 by screen printing, spin coating or glue dispensing, and then pasted with the reflective layer 43 , and the process sequence is not limited here.

As shown in FIG. 5F to FIG. 5I , step S16 to step S19 are the same as step S06 to step S09 in the first embodiment, so they will not be repeated here. That is, step S16 turns over the electroluminescent device 4 formed in the above steps; step S17 removes the plate body 41; step S18 removes part of the light emitting diode element 42 to expose part of the reflective layer 43; finally forms the contact electrode 47 step, step S19 forms a first contact electrode 471 on a portion of the first semiconductor layer 421 , and forms a second contact electrode 472 on an exposed portion of the reflective layer 43 to form the electroluminescent device 4 .

In this embodiment, the step of removing part of the LED element 42 includes: forming a photoresist layer on the second semiconductor layer 423; irradiating the photoresist layer with light through a mask; removing part to form a patterned photoresist layer; remove part of the second semiconductor layer 423, part of the light emitting layer 422 and part of the first semiconductor layer 421; and remove the patterned photoresist resist layer to expose part of the reflective layer 43 .

To sum up, according to an electroluminescent device and its manufacturing method of the present invention, a thermally conductive adhesive layer, a thermally conductive substrate, or even a thermally conductive insulating layer with high thermal conductivity is used to effectively conduct the heat energy generated by the light-emitting diode element. to the outside world to improve the luminous efficiency of the electroluminescent device. In addition, since the method of screen printing, spin coating or dispensing to form the thermally conductive adhesive layer is a method with mature technology and low cost, the production cost can be reduced and the yield rate can be increased. Furthermore, disposing a heat-conducting insulating layer on the heat-conducting substrate and the light-emitting diode element can effectively prevent the short circuit between them and increase the heat dissipation efficiency. Finally, using the metal reflective layer with ohmic contact function to reflect the light generated by the light emitting diode element will improve the external light extraction efficiency of the electroluminescent device.

The above description is only illustrative, not restrictive. Any equivalent modification or change without departing from the spirit and scope of the present invention shall be included in the claims.

Claims (20)

1. A method for manufacturing an electroluminescent device, comprising the following steps: Forming a light emitting diode element on the board body, the light emitting diode element sequentially includes a first semiconductor layer, a light emitting layer and a second semiconductor layer, the first semiconductor layer is formed on the board body; forming a reflective layer on the light emitting diode element; disposing a thermally conductive adhesive layer on the reflective layer; disposing a thermally conductive substrate over the thermally conductive adhesive layer; and Remove the board. 2. The manufacturing method according to claim 1, wherein the first semiconductor layer is an n-type doped layer, and the second semiconductor layer is a p-type doped layer. 3. The manufacturing method according to claim 1, further comprising: A thermally conductive insulating layer is formed on the reflective layer or the thermally conductive substrate. 4. The manufacturing method according to claim 3, wherein the thermally conductive adhesive layer is formed on the thermally conductive insulating layer by screen printing, spin coating or dispensing and pasted with the thermally conductive substrate, or formed on the thermally conductive substrate or formed on the thermally conductive insulating layer and bonded to the reflective layer, or formed on the reflective layer and bonded to the thermally conductive insulating layer. 5. The manufacturing method as claimed in claim 3, wherein the material of the thermally conductive insulating layer is aluminum nitride or silicon carbide. 6. The manufacturing method according to claim 3, wherein the thermally conductive insulating layer is formed on the reflective layer by reactive sputtering, non-reactive sputtering, or high temperature nitriding. 7. The manufacturing method as claimed in claim 1, wherein the material of the thermally conductive adhesive layer is solder paste, tin-silver paste, silver paste, or joint solder composed of other alloys. 8. The manufacturing method as claimed in claim 1, wherein the step of removing the board is removing the board by a laser lift-off process. 9. The manufacturing method as claimed in claim 1, wherein after removing the board, further comprising the steps of: Part of the LED element is removed to expose part of the reflective layer. 10. The manufacturing method according to claim 9, wherein the step of removing part of the light emitting diode element comprises: forming a photoresist layer on the second semiconductor layer; illuminating the photoresist layer with light through a mask; removing part of the photoresist layer to form a patterned photoresist layer; removing part of the second semiconductor layer, part of the light emitting layer and part of the first semiconductor layer; and The patterned photoresist layer is removed. 11. The manufacturing method as claimed in claim 9, wherein after removing part of the LED element, further comprising the step of: A first contact electrode is formed on the first semiconductor layer. 12. The manufacturing method as claimed in claim 9, wherein after removing part of the LED element, further comprising the step of: A second contact electrode is formed, and the second contact electrode is located on the exposed portion of the reflective layer. 13. The manufacturing method according to claim 1, wherein the reflective layer is an ohmic contact metal reflective layer, and the material of the reflective layer is selected from platinum, gold, silver, palladium, nickel, chromium, titanium and combinations thereof Group. 14. The manufacturing method according to claim 1, wherein the process temperature is between 25°C and 300°C. 15. An electroluminescent device comprising: thermally conductive adhesive layer; a thermally conductive substrate, disposed on one side of the thermally conductive bonding layer; a reflective layer arranged on the other side of the thermally conductive adhesive layer; A light-emitting diode element is disposed on the reflective layer and exposes part of the reflective layer. The light-emitting diode element has a first semiconductor layer, a light-emitting layer, and a second semiconductor layer in sequence, and the second semiconductor layer is in contact with the reflective layer; a first contact electrode electrically connected to the first semiconductor layer; and The second contact electrode is located on the exposed portion of the reflective layer, and the second contact electrode is electrically connected to the reflective layer. 16. The electroluminescent device of claim 15, further comprising: The heat-conducting insulating layer is arranged between the heat-conducting substrate and the heat-conducting adhesive layer, or the heat-conducting insulating layer is arranged between the heat-conducting adhesive layer and the reflective layer. 17. The electroluminescent device as claimed in claim 16, wherein the material of the thermally conductive insulating layer is selected from aluminum nitride or silicon carbide. 18. The electroluminescence device as claimed in claim 15, wherein the material of the thermally conductive adhesive layer is solder paste, tin-silver paste, silver paste, or a joint solder composed of other alloys. 19. The electroluminescence device as claimed in claim 15, wherein the reflective layer is an ohmic contact metal reflective layer, and the material of the reflective layer is selected from platinum, gold, silver, palladium, nickel, chromium, titanium and combinations thereof formed group. 20. The electroluminescent device as claimed in claim 15, wherein the material of the thermally conductive substrate is selected from the group consisting of silicon, gallium arsenide, gallium phosphide, silicon carbide, boron nitride, aluminum, aluminum nitride, copper and combinations thereof formed group.

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