Patent Application
20240413265
This application claims priority to Japanese Patent Application No. 2023-096368, filed above Jun. 12, 2023, the disclosure of which is hereby incorporated by reference in its entirety.
The present disclosure relates to a method for manufacturing a light-emitting device.
Japanese Patent Publication No. 2010-141176 discloses a method for manufacturing a light-emitting device that includes: a step of detaching a substrate above which a semiconductor layered body is grown, to expose a first surface of the semiconductor layered body; a step of forming a phosphor layer above the exposed first surface; and a step of performing singulation after forming the phosphor layer above the first surface.
An object of the present disclosure is to provide a method for manufacturing a light-emitting device that allows easy singulation while reducing damage to a layered body.
According to an aspect of the present disclosure, a method for manufacturing a light-emitting device includes providing a layered body including a wavelength conversion layer, a light-transmissive layer disposed above the wavelength conversion layer, and a semiconductor layer disposed above the light-transmissive layer; separating the semiconductor layer into a plurality of semiconductor portions above the wavelength conversion layer by removing a part of the semiconductor layer; and singulating the layered body into a plurality of light-emitting devices by cleaving the wavelength conversion layer along a portion where the part of the semiconductor layer is removed.
The present disclosure can provide a method for manufacturing a light-emitting device that allows easy singulation while reducing damage to a layered body.
Embodiments are described below with reference to the drawings. In the drawings, the same constituent elements are denoted using the same reference signs. Note that the drawings schematically illustrate embodiments, and thus scales, intervals, positional relationships, and the like of members may be exaggerated, or some of the members are not illustrated in the drawings in some cases. As a cross-sectional view, an end view illustrating only a cut surface may be illustrated. In the cross-sectional view, the cross section of a semiconductor layer is not hatched in order to make it easy to see the boundary between layers of the semiconductor layer.
In the following description, components having substantially the same function may be denoted by the same reference signs and a description thereof may be omitted. Terms indicating a specific direction or position (for example, “upper”, “upward”, “lower”, “downward”, and other terms including or related to those terms) may be used. However, these terms are used merely to make it easy to understand relative directions or positions in the referenced drawing. As long as the relative direction or position is the same as that described in the referenced drawing using the term such as “upper” “upward”, “lower”, or “downward” in drawings other than the drawings of the present disclosure, actual products, and the like, components need not be arranged in the same manner as that in the referenced drawing. In the present specification, a positional relationship expressed by using the term “on” includes a case in which an object is in contact and also a case in which an object is not in contact but located above. In the present specification, unless otherwise specified, a case in which a member covers an object to be covered includes a case in which the member is in contact with the object to be covered and directly covers the object to be covered, and a case in which the member is not in contact with the object to be covered and indirectly covers the object to be covered. A “plan view” refers to a plan view in which a semiconductor layer above a wavelength conversion layer is viewed from above.
A method for manufacturing a light-emitting device 1 according to a first embodiment is described with reference to
The method for manufacturing the light-emitting device according to the first embodiment includes a step of providing a layered body 101 including a wavelength conversion layer 30, a light-transmissive layer 20, and a semiconductor layer 10, a step of separating the semiconductor layer 10 into a plurality of semiconductor portions 60 above the wavelength conversion layer 30, and a step of singulating the layered body 101 into a plurality of light-emitting devices 1 by cleaving the wavelength conversion layer 30.
As illustrated in
The semiconductor layer 10 includes an n-side semiconductor layer 11, a p-side semiconductor layer 13, and an active layer 12 located between the n-side semiconductor layer 11 and the p-side semiconductor layer 13. The active layer 12 is a light-emitting layer that emits light, and emits light having a light emission peak wavelength in a range from 210 nm to 580 nm, for example. The active layer 12 may have, for example, a multiple quantum well (MQW) structure including a plurality of barrier layers and a plurality of well layers. The n-side semiconductor layer 11 includes a semiconductor layer containing n-type impurities. The p-side semiconductor layer 13 includes a semiconductor layer containing p-type impurities.
The semiconductor layer 10 has a first surface 10a located on an opposite side to a surface above which the active layer 12 and the p-side semiconductor layer 13 are disposed. Light emitted by the active layer 12 is mainly extracted from the first surface 10a to the outside of the semiconductor layer 10.
The n-side semiconductor layer 11 has a first n-side exposed surface 11a and a second n-side exposed surface 11b that are located on the opposite side of the first surface 10a and exposed from the active layer 12 and the p-side semiconductor layer 13.
The semiconductor layer 10 is formed of a nitride semiconductor. In the present specification, for example, it is assumed that the “nitride semiconductor” includes semiconductors having all compositions of a chemical formula of InxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, x+y≤1) provided that the composition ratios x and y are changed within the respective ranges. In the above chemical formula, it is assumed that the “nitride semiconductor” includes a semiconductor further containing a group V element other than nitrogen (N), and a semiconductor further containing various elements added to control various physical properties such as a conductivity type.
The wavelength conversion layer 30 converts the wavelength of at least a part of light emitted by the active layer 12. As the wavelength conversion layer 30, a sintered body that is formed by sintering powder of a phosphor and is substantially made of only the phosphor can be used. Alternatively, as the wavelength conversion layer 30, a light-transmissive material containing a phosphor can be used. Examples of the light-transmissive material that can be used include ceramics, a resin, and glass. Examples of the phosphor that can be used include a cerium-activated yttrium-aluminum-garnet-based phosphor (for example, (Y,Gd)3(Al,Ga)5O12:Ce), and a cerium-activated lutetium-aluminum-garnet-based phosphor (for example, Lu3(Al,Ga)5O12:Ce). A thickness of the wavelength conversion layer 30 can be, for example, in a range from 30 μm to 500 μm.
The light-transmissive layer 20 is located between the semiconductor layer 10 and the wavelength conversion layer 30. Because the light-transmissive layer 20 is located between the semiconductor layer 10 and the wavelength conversion layer 30, the bonding force between the semiconductor layer 10 and the wavelength conversion layer 30 can be easily increased as compared with a case in which the semiconductor layer 10 and the wavelength conversion layer 30 are directly bonded to each other.
The light-transmissive layer 20 has high light transmissivity with respect to light emitted by the active layer 12. The fact that the light-transmissive layer 20 has high light transmissivity means that the light-transmissive layer 20 has a light transmittance of 50% or more, preferably 60% or more, more preferably 80% or more with respect to the light emission peak wavelength of the light emitted by the active layer 12.
The light-transmissive layer 20 preferably has a refractive index between a refractive index of the semiconductor layer 10 and a refractive index of the wavelength conversion layer 30. Thus, the difference between the refractive index of the semiconductor layer 10 and the refractive index of the wavelength conversion layer 30 can be reduced, and reflection of light emitted by the active layer 12 between the semiconductor layer 10 and the wavelength conversion layer 30 can be reduced. For example, the refractive index of the semiconductor layer 10 can be appropriately selected in a range from 2.3 to 2.6, the refractive index of the wavelength conversion layer 30 can be appropriately selected in a range from 1.7 to 1.9, and the refractive index of the light-transmissive layer 20 can be appropriately selected in a range from 1.6 to 2.4.
Examples of a material for the light-transmissive layer 20 that can be used include SiO2, SiN, SiON, Al2O3, Nb2O5, and TiO2. A thickness of the light-transmissive layer 20 can be, for example, in a range from 2 μm to 50 μm.
Step of Separating Semiconductor Layer into Plurality of Semiconductor Portions:
After the layered body 101 is provided, a part of the semiconductor layer 10 is removed to separate the semiconductor layer 10 into the plurality of semiconductor portions 60 above the wavelength conversion layer 30 as illustrated in
A portion below the second n-side exposed surface 11b of the n-side semiconductor layer 11 is removed, and the semiconductor layer 10 is separated into the plurality of semiconductor portions 60. In the step of separating the semiconductor layer 10 into the plurality of semiconductor portions 60, the part of the semiconductor layer 10 is preferably removed by etching. Thus, chipping of the semiconductor layer 10 is less likely to occur than in a case in which the part of the semiconductor layer 10 is removed using a blade.
For example, a portion other than a part of the second n-side exposed surface 11b in the layered body 101 is covered with a mask, and the part of the semiconductor layer 10 formed of a nitride semiconductor can be removed by a reactive ion etching (RIE) method using a chlorine-containing gas. The etching proceeds toward the first surface 10a in the thickness direction of the semiconductor layer 10 from the second n-side exposed surface 11b exposed from the mask. For example, a resist mask can be used as the mask.
In the example illustrated in
For example, when the light-transmissive layer 20 contains silicon oxide, the part of the light-transmissive layer 20 can be removed by the RIE method using a fluorine-containing gas. In the case of the RIE method, the part of the semiconductor layer 10 and the part of the light-transmissive layer 20 can be successively removed by switching the type of gas.
Step of Singulating Layered Body into Plurality of Light-Emitting Devices:
After the semiconductor layer 10 is separated into the plurality of semiconductor portions 60, the wavelength conversion layer 30 is cleaved along the portion 10A where the part of the semiconductor layer 10 is removed, thereby singulating the layered body 101 into the plurality of light-emitting devices 1 as illustrated in
For example, the wavelength conversion layer 30 can be cleaved by irradiating the wavelength conversion layer 30 with laser light and applying a pressing force to the wavelength conversion layer 30.
As illustrated in
The laser light L is condensed at a specific depth position inside the wavelength conversion layer 30, the energy of the laser light L is concentrated at this position, and a modified portion 200 is formed inside the wavelength conversion layer 30. The modified portion 200 is a portion more embrittled than a portion where the laser light L is not condensed. The laser light L scans along the portion 10A where the part of the semiconductor layer 10 is removed, and a plurality of modified portions 200 are formed along the portion 10A where the part of the semiconductor layer 10 is removed. The modified portion 200 formed by the irradiation with the laser light L generates stress, and this stress causes cracks inside the wavelength conversion layer 30. The cracks extend in the thickness direction of the wavelength conversion layer 30 from the modified portion 200.
After the modified portion 200 is formed by the irradiation with the laser light L, as illustrated in
When the layered body 101 is singulated into the plurality of light-emitting devices 1, a method of collectively cleaving, cutting, or etching the semiconductor layer 10 and the wavelength conversion layer 30 by the same method is conceivable. In the method of collectively cleaving the semiconductor layer 10 and the wavelength conversion layer 30, the semiconductor layer 10 is unlikely to be cleaved. In the method of collectively cutting the semiconductor layer 10 and the wavelength conversion layer 30 by using a blade, chipping is likely to occur in the semiconductor layer 10 harder than the wavelength conversion layer 30. In the method of collectively etching the semiconductor layer 10 and the wavelength conversion layer 30, it takes time to etch the wavelength conversion layer 30 thicker than the semiconductor layer 10, so that the manufacturing efficiency of the light-emitting device may be reduced.
According to the present embodiment, after the semiconductor layer 10 is separated into the plurality of semiconductor portions 60 above the wavelength conversion layer 30, the layered body 101 is singulated into the plurality of light-emitting devices 1 by cleaving the wavelength conversion layer 30; thus, respective methods suitable for the separation of the semiconductor layer 10 into the semiconductor portions 60 and the cleavage of the wavelength conversion layer 30 can be selected. Thus, the layered body 101 can be easily singulated into the plurality of light-emitting devices 1 while reducing damage to the layered body 101.
The third surface 30b of the wavelength conversion layer 30 in the light-emitting device 1 is a main light extraction surface. In the light-emitting device 1, light can also be extracted from the lateral surface of the semiconductor layer 10, the lateral surface of the light-transmissive layer 20, and the lateral surface of the wavelength conversion layer 30.
As illustrated in
A part of the second surface 30a of the wavelength conversion layer 30 located below the portion where the part of the semiconductor layer 10 and the part of the light-transmissive layer 20 are removed serves as an outer peripheral portion 30al exposed from the light-transmissive layer 20 and the semiconductor layer 10 in the light-emitting device 1 obtained by singulation, as illustrated in
In the step of providing the layered body 101 illustrated in
The conductive layer 40 is disposed above the p-side semiconductor layer 13 and is electrically connected to the p-side semiconductor layer 13. The conductive layer 40 has a function of diffusing, in a plane direction of the p-side semiconductor layer 13, electric current supplied from a p-side electrode to be described below.
The conductive layer 40 may have high reflectivity with respect to light emitted by the active layer 12. The conductive layer 40 having high reflectivity represents that the conductive layer 40 has a reflectance of 50% or more, preferably 60% or more with respect to the light emission peak wavelength of the light emitted by the active layer 12. For example, silver or aluminum can be used as a material for the conductive layer 40.
The first insulating film 51 covers an upper surface of the p-side semiconductor layer 13 and the conductive layer 40. The first insulating film 51 covers the conductive layer 40, so that the influence of moisture or the like above the conductive layer 40 can be reduced and the occurrence of migration of the conductive layer 40 can be reduced. For example, a silicon oxide film or a silicon nitride film can be used as the first insulating film 51.
The second insulating film 52 covers the first insulating film 51. The second insulating film 52 covers a part of the first n-side exposed surface 11a and a part of the second n-side exposed surface 11b. The second insulating film 52 further covers the lateral surface of the semiconductor layer 10 continuous with the first n-side exposed surface 11a and the upper surface of the p-side semiconductor layer 13, and the lateral surface of the semiconductor layer 10 continuous with the second n-side exposed surface 11b and the upper surface of the p-side semiconductor layer 13.
In the step of providing the layered body 101, the layered body 101 illustrated in
The step of providing the layered body 101 may include a step of providing a wafer W, a step of removing a first substrate 91 of the wafer W to expose the first surface 10a of the semiconductor layer 10, a step of forming the light-transmissive layer 20 above the first surface 10a, and a step of bonding the wavelength conversion layer 30 to the light-transmissive layer 20.
In the step of providing the wafer W, as illustrated in
The first substrate 91 is a substrate used for formation of the semiconductor layer 10 by a metal organic chemical vapor deposition (MOCVD) method, for example. A sapphire substrate can be used as the first substrate 91, for example.
In the step of removing the first substrate 91 of the wafer W, the first substrate 91 can be removed by, for example, a laser lift-off method. The first substrate 91 is removed from the wafer W, so that the first surface 10a of the semiconductor layer 10 is exposed as illustrated in
On the exposed first surface 10a, the light-transmissive layer 20 is formed as illustrated in
As illustrated in
The step of providing the layered body 101 preferably includes a step of bonding the wafer W to the second substrate 92 such that the second substrate is bonded to a surface side of the wafer W opposite to the first substrate 91, as illustrated in
A substrate formed of the same material as the first substrate 91 can be used as the second substrate 92. The surface side of the wafer W opposite to the first substrate 91 is bonded to the second substrate 92 by a bonding member 93. For example, a resin can be used as a material for the bonding member 93.
The step of providing the layered body preferably further includes a step of, after the first surface 10a of the semiconductor layer 10 is exposed by removing the first substrate 91, roughening the first surface 10a as illustrated in
For example, the first surface 10a can be roughened by wet etching using an alkaline solution such as tetramethylammonium hydroxide (TMAH) or dry etching using a chlorine-containing gas.
When the first surface 10a is roughened, the light-transmissive layer 20 is formed above the roughened first surface 10a as illustrated in
After the wavelength conversion layer 30 is bonded to the light-transmissive layer 20, the second substrate 92 is removed. For example, the second substrate 92 can be detached from the bonding member 93 by irradiating an interface between the second substrate 92 and the bonding member 93 with laser light to evaporate the bonding member 93 located at the interface. Subsequently, the bonding member 93 can be removed from the semiconductor layer 10 by being dissolved using, for example, a chemical solution.
The thickness of the part of the semiconductor layer 10 removed in the step of separating the semiconductor layer 10 into the plurality of semiconductor portions 60 is preferably greater than the thickness of the light-transmissive layer 20. This can make it difficult for cracks to occur in the semiconductor layer 10 due to internal stress of the light-transmissive layer 20 formed above the first surface 10a of the semiconductor layer 10.
The method for manufacturing the light-emitting device according to the first embodiment can further include a step of forming a p-side electrode 71 and an n-side electrode 72 above the second insulating film 52 as illustrated in
The p-side electrode 71 is in contact with an upper surface of the conductive layer 40 in an opening formed in the second insulating film 52 and an opening formed in the first insulating film 51. The p-side electrode 71 is electrically connected to the p-side semiconductor layer 13 via the conductive layer 40. The n-side electrode 72 is in contact with the first n-side exposed surface 11a and is electrically connected to the n-side semiconductor layer 11.
Materials for the p-side electrode 71 and the n-side electrode 72, for example, a metal material such as Ag, Ni, Ti, Pt, Al, Ru, Rh, or Au, or an alloy thereof can be used. The p-side electrode 71 and the n-side electrode 72 may each be a single layer formed of any of the above metal materials, or may each have a layered structure including a plurality of metal layers.
The method for manufacturing the light-emitting device according to the first embodiment can further include a step of forming a p-side external connection electrode 81 and an n-side external connection electrode 82 as illustrated in
The p-side external connection electrode 81 is formed above the p-side electrode 71 and is electrically connected to the p-side electrode 71. The n-side external connection electrode 82 is formed above the n-side electrode 72 and is electrically connected to the n-side electrode 72. A thickness of the p-side external connection electrode 81 and a thickness of the n-side external connection electrode 82 are greater than a thickness of the p-side electrode 71 and a thickness of the n-side electrode 72.
As materials for the p-side external connection electrode 81 and the n-side external connection electrode 82, for example, a metal material such as Ag, Ni, Ti, Pt, Al, Ru, Rh, or Au, or an alloy thereof can be used. Each of the p-side external connection electrode 81 and the n-side external connection electrode 82 may be a single layer formed of any of the above metal materials, or may have a layered structure including a plurality of metal layers.
Steps of forming the p-side electrode 71, the n-side electrode 72, the p-side external connection electrode 81, and the n-side external connection electrode 82 may each be performed at discretionary timing as long as the step is performed before the wavelength conversion layer 30 is cleaved. When a resist mask is used in the step of removing the part of the semiconductor layer 10 by etching, the resist mask is preferably disposed above the layered body 101 before the p-side external connection electrode 81 and the n-side external connection electrode 82 are formed. In that case, the resist mask can be disposed above the layered body 101 in a state of being thinner than the layered body 101 in a state in which the p-side external connection electrode 81 and the n-side external connection electrode 82 are formed, and the accuracy of patterning of the resist mask by exposure and development can be easily improved.
A method for manufacturing a light-emitting device 2 according to a second embodiment is described with reference to
According to the second embodiment, as illustrated in
Subsequently, in the step of singulating the layered body 101 into a plurality of light-emitting devices 2, the light-transmissive layer 20 and the wavelength conversion layer 30 are cleaved along the portion 10A where the part of the semiconductor layer 10 is removed. The light-transmissive layer 20 is also cleaved along with the cleavage of the wavelength conversion layer 30 described above.
According to the second embodiment, as illustrated in
A method for manufacturing a light-emitting device 3 according to a third embodiment is described with reference to
According to the third embodiment, as illustrated in
As illustrated in
The first light-transmissive layer 121 including the plurality of dielectric layers has characteristics of easily transmitting light in a wavelength region of light emitted by the active layer 12 and easily reflecting light in a wavelength region of light wavelength-converted by the wavelength conversion layer 30. The first light-transmissive layer 121 having such characteristics can improve efficiency of light extraction from the third surface 30b of the wavelength conversion layer 30 in the light-emitting device 3.
For example, niobium oxide (Nb2O5) can be used as a material for one of the first dielectric layer 121a and the second dielectric layer 121b, and silicon oxide (SiO2) can be used as a material for the other dielectric layer.
According to the third embodiment, as illustrated in
Subsequently, in the step of singulating the layered body 102 into a plurality of light-emitting devices 3, the first light-transmissive layer 121 and the wavelength conversion layer 30 are cleaved along the portion 10A where the part of the semiconductor layer 10 is removed. The first light-transmissive layer 121 is also cleaved along with the cleavage of the wavelength conversion layer 30 described above.
According to the third embodiment, as illustrated in
In the step of providing the layered body 102 of the third embodiment, as illustrated in
The embodiments according to the present disclosure can include the methods for manufacturing the light emitting device as below.
The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. All aspects that can be practiced by a person skilled in the art changing the design as appropriate based on the above-described embodiments of the present invention are also included in the scope of the present invention, as long as they encompass the spirit of the present invention. In addition, in the spirit of the present invention, a person skilled in the art can conceive of various alteration examples and modifications, and those alteration examples and modifications will also fall within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-096368 | Jun 2023 | JP | national |
