Patent Application
20110298001
Embodiments described herein relate generally to a method for manufacturing a light-emitting device and a light-emitting device manufactured by the same.
The applications of light-emitting devices have expanded to lighting apparatuses, back-light sources for image-displaying apparatuses, displaying apparatuses, and the like.
In recent years, light-emitting devices smaller in size have been demanded. In a manufacturing method proposed to enhance mass productivity, a semiconductor layer including a light-emitting layer is formed on a substrate by crystal growth, then the substrate is removed from the semiconductor layer by laser-light irradiation, and thereafter the resultant semiconductor layer is divided into multiple devices.
In the process of removing the substrate from the semiconductor layer by the laser-light irradiation, the laser light enters an insulating film that covers the semiconductor layer, and the energy of the laser light heats not only the side surfaces of the semiconductor layer but also electrodes.
In general, according to one embodiment, a method for manufacturing a light-emitting device is disclosed. The method can include removing a substrate from a semiconductor layer. The semiconductor layer is provided on a first main surface of the substrate. The semiconductor layer includes a light-emitting layer. At least a top surface and side surfaces of the semiconductor layer are covered with a first insulating film. A first electrode portion electrically continuous to the semiconductor layer is provided. A second electrode portion electrically continuous to the semiconductor layer is provided. The first insulating film is covered with a second insulating film. The removing is performed by irradiating the semiconductor layer with laser light from a side of a second main surface of the substrate. The second main surface is opposite to the first main surface. The first insulating film is made of silicon nitride. Band-gap energy of the first insulating film is smaller than energy of the laser light. The second insulating film is made of polyimide. Each of band-gap energy of the second insulating film and band-gap energy of the semiconductor layer are smaller than energy of the laser light.
According to another embodiment, a light-emitting device includes a semiconductor layer, a first electrode portion and a second electrode portion, a first insulating film and a second insulating film. The semiconductor layer includes a light-emitting layer. The first electrode portion and the second electrode portion are provided on a second main surface of the semiconductor layer, and the second main surface is opposite to a first main surface of the semiconductor layer. The first insulating film covers at least side surfaces of the semiconductor layer and the second insulating film covers the first insulating film. The first insulating film is made of silicon nitride. The second insulating film is made of polyimide.
Some embodiments of the invention will be described below with reference to the drawings.
The drawings are only schematic or conceptual ones. The relationship between the thickness and the width of each portion, the size ratio between of portions, or the like are not necessarily the same as those in the actual ones. In addition, a portion may be shown with different dimensions or different size ratios between the drawings.
In addition, in the description and the drawings, the same element as that described with reference to a preceding drawing are assigned the same reference numerals, and the detailed description thereof is omitted herein.
As shown in
In step S110, a semiconductor layer including a light-emitting layer (active layer) is formed on a first main surface of a substrate.
In step S120, a first insulating film is formed to cover at least the top surface of and the side surfaces of the semiconductor layer that has been formed on the substrate.
In step S130, a first electrode portion and a second electrode portion are formed so as to be electrically continuous to the semiconductor layer.
In step S140, a second insulating film is covered with the first insulating film.
In step S150, a second main surface of the substrate, which is on the opposite side to the first main surface, is irradiated with laser light, and the substrate is removed from the semiconductor layer.
In the manufacturing method of this embodiment, both the band-gap energy of the second insulating film and that of the semiconductor layer are smaller than the energy of the laser light. In addition, in this embodiment, portions of the first insulating film cover the side surfaces of the semiconductor layer, and that portions suppress the advancing of the laser light emitted to remove the substrate. To put it differently, the laser light cannot progress so deeply as to reach the light-emitting layer on the side-surfaces of the semiconductor layer from the first main surface in the first insulating film covering the side surfaces of the semiconductor layer.
The first insulating film covering the side surfaces of the semiconductor layer suppresses the advancing of the laser light emitted to remove the substrate and thus effects on the side-surface portions of the semiconductor layer by irradiation with the laser light are reduced. To be more specific, the laser-light irradiation onto the side surfaces of the semiconductor layer heats the side-surface portions, resulting in the degradation of the characteristics. In this embodiment, the side surfaces of the semiconductor layer are irradiated with no laser light, so that the degradation of the semiconductor layer by the heating can be prevented. In particular, the degradation of the light-emitting layer included in the semiconductor layer can be avoided. Consequently, the stable light-emitting characteristics are maintained. In addition, laser-light irradiation onto the side surfaces of the semiconductor layer may cause removal of the first insulating film at the interface, but the removal of the first insulating film at this interface can also be avoided in this embodiment.
The portion of the first insulating film covering the side surfaces of the semiconductor layer can suppress the advancing of the laser light, provided that any of the following two conditions is satisfied:
(1) Firstly, at least part of the portions of the first insulating film that cover the respective side surfaces of the semiconductor layer between the first main surface and the light-emitting layer has a smaller thickness, in a direction perpendicular to the side surfaces, than a wavelength of the laser light.
(2) Secondly, the band-gap energy of the first insulating film is smaller than the energy of the laser light.
If any of the conditions (1) and (2) is satisfied, the advancing of the laser light in the first insulating film that covers the side surfaces of the semiconductor layer is blocked, or is made more difficult. Accordingly, the laser light cannot reach the position of the light-emitting layer on the side-surfaces of the semiconductor layer from the first main surface of the substrate. Consequently, the effects on the side-surface of the semiconductor layer is reduced.
Subsequently, a specific method for manufacturing a light-emitting device will be described with reference to
The method for manufacturing a light-emitting device of this specific example satisfies the first condition (1).
Firstly, as shown in
Subsequently, a part of the second semiconductor layer 12 and a part of the first semiconductor layer 11 are selectively removed by, for example, reactive ion etching (RIE) method using unillustrated resist. Consequently, as shown in
Grooves 8 are formed so as to pierce the semiconductor layer 5 and reach the substrate 10. The grooves 8 sub-divide the semiconductor layer 5 into plural sections on the substrate 10. For example, as shown in
Subsequently, as shown in
In this embodiment, portions of the first insulating film 13 that cover the side surfaces 5b of the semiconductor layer 5 are provided to reach the first main surface 10a of the substrate 10. In addition, in the formation of the first insulating film 13 in this embodiment, the thickness t (the thickness measured in the direction perpendicular to the side surfaces 5b) of each of the portions of the first insulating film 13 covering the side surfaces 5b of the semiconductor layer 5 is smaller than the wavelength of the laser light to be used to remove the substrate 10.
The laser light to be used is, for example, light of ArF laser (wavelength: 193 nm), light of KrF laser (wavelength: 248 nm), light of XeCl laser (wavelength: 308 nm), or light of XeF laser (wavelength: 353 nm). The first insulating film 13 is is formed to have the thickness t smaller than the wavelength of the laser light that is to be used actually.
Subsequently, openings are selectively formed in the first insulating film 13. As shown in
Subsequently, as shown in
After the formation of the second insulating film 16, both an opening 16a that reaches the n-side electrode 14 and an opening 16b that reaches the p-side electrode 15 are formed in the second insulating film 16 as shown in
Subsequently, seed metal (not illustrated) is formed on the top surface of the second insulating film 16 as well as on the inner walls (the side surfaces and bottom surfaces) of the opening 16a and the opening 16b, and then resist for plating (not illustrated) is formed, and, after that, a Cu plating process is performed with the seed metal used as a current pathway. The seed meal contains Cu, for example.
Consequently, as shown in
Subsequently, after the resist for plating that has been used in the plating of the n-side interconnection 17 and of the p-side interconnection 18 is removed using a chemical solution, other resist for plating for forming metal pillars is formed and a process of electrolytic plating is performed with the seed metal mentioned above used as a current pathway. Thus, as shown in
After that, the resist for forming metal pillars is removed using a chemical solution, and then exposed portions of the seed metal are removed. Consequently, the electric connection between the n-side interconnection 17 and the p-side interconnection 18 through the seed metal is cut off.
Subsequently, as shown in
Subsequently, as shown in
Laser light LSR to be used is, for example, light of ArF laser (wavelength: 193 nm), light of KrF laser (wavelength: 248 nm), light of XeCl laser (wavelength: 308 nm), or light of XeF laser (wavelength: 353 nm).
The laser light LSR is thrown upon the semiconductor layer 5 from the side of a second main surface 10b (the opposite side to the first main surface 10a) of the substrate 10 towards the semiconductor layer 5. The laser light LSR passes through the substrate 10, and reaches a lower surface 5c of the semiconductor layer 5. The second insulating film 16 (irrespective of silicon nitride or a resin) and the semiconductor layer 5 absorb the laser light LSR. The second insulating film 16 and the semiconductor layer 5 are made of materials which absorb the laser light LSR having a wavelength longer than 248 nm. Alternatively, the band-gap energy of the second insulating film 16 and the band-gap energy of the semiconductor layer 5 are smaller than the energy of the laser light LSR. Consequently, the laser light LSR that has passed through the substrate 10 is absorbed by the semiconductor layer 5 and the second insulating film 16. In the meanwhile, at the interface of the substrate 10 and semiconductor layer 5, the absorption of the laser light LSR causes the GaN component in the semiconductor layer 5 to be thermally decomposed in a manner shown in the following reaction formula, for example.
GaN→Ga+(½)N2↑
Consequently, as shown in
In this embodiment, the thickness t of the first insulating film 13 covering the side surfaces 5b of the semiconductor layer 5 is smaller than the wavelength of the laser light LSR. Accordingly, the diffraction limit of the laser light LSR prevents the entry of the laser light LSR into the inside (inside of the first insulating film 13) from the end surfaces of the portions of the first insulating film 13 on the side of a lower surface 5c of and covering the side surfaces 5b of the semiconductor layer 5.
If the thickness t of the first insulating film 13 is equal to or larger than the wavelength of the laser light LSR, the laser light LSR enters the first insulating film 13. In contrast, if the thickness t of the first insulating film 13 is smaller than the wavelength of the laser light LSR, the diffraction limit of the laser light LSR suppresses drastically the entry of the laser light LSR into the first insulating film 13.
If the entry of the laser light LSR is suppressed in this way, the degradation of the semiconductor layer 5, especially, that of the light-emitting layer of the second semiconductor layer 12, is avoided. Consequently, stable light-emitting characteristics can be maintained. In addition, removal of the first insulating film 13 is prevented from occurring at the interface between each of the side surfaces 5b of the semiconductor layer 5 and the first insulating film 13. In addition, the effects of the irradiation of the laser light LSR on the second insulating film 16 that is in contact with the first insulating film 13 near the side surfaces 5b, such as the melting of the second insulating film 16, can be reduced. Consequently, the lowering of the reliability is suppressed.
After that, as shown in
Since the use of this manufacturing method allows the light-emitting device 110 to be built at the wafer level, CSP (Chip Size Package) of the light-emitting device 110, whose size is as small as the size of the bare chip, can be provided easily. In addition, after building at the wafer level, the light-emitting devices 110 may be completed by dicing into individuals. The cutting method is, for example, the mechanical machining using a diamond blade or the like, the cutting by laser irradiation, or the cutting by high-pressured water.
Subsequently, description will be given of another example of the method for manufacturing a light-emitting device according to the first embodiment.
The method for manufacturing a light-emitting device of this specific example satisfies the second condition (2) mentioned above.
Specifically, the first insulating film 13 made of a material whose band-gap energy is smaller than the energy of the laser light LSR is used. For example, the first insulating film 13 is made of a material containing a nitride, or, to be more specific, a material containing silicon nitride, for example.
In this example, the processes from the formation of the first semiconductor layer 11 and the second semiconductor layer 12 until the laser lift off are similar to those shown in
Since the first insulating film 13 is made of a material whose band-gap energy is smaller than the energy of the laser light LSR, there is no limit to the thickness t of the first insulating film 13 on the side surfaces 5b of the semiconductor layer 5. If the band-gap energy of the first insulating film 13 is smaller than the energy of the laser light LSR, the transmissibility of the laser light LSR drops significantly. Consequently, the entry, into the first insulating film 13, of the laser light LSR thrown upon at the laser lift off is suppressed.
The energy of the laser light LSR is calculated by the following formula.
E=h×(c/λ)
where E is the energy, h is the Planck's constant, c is the speed of light, and λ is the wavelength.
If, for example, light of the KrF laser (wavelength: 248 nm) is used as the laser light LSR, the energy is approximately 5.0 eV. In this case, the material to be used for the first insulating film 13 has band-gap energy that is smaller than 5.0 eV. For example, silicon nitride (SiN) is used. Note that the band-gap energy of the silicon nitride (SiN) varies depending on the composition ratio of Si and N. Accordingly, the silicon nitride to be used may be one with a composition ratio that makes the band-gap energy smaller than 5.0 eV.
As shown in
In the meanwhile, the surface of the first insulating film 13b located at the interfaces of the first insulating film 13 and the substrate 10 is irradiated with the laser light LSR. The band-gap energy of the first insulating film 13b is smaller than the energy of the laser light LSR. Accordingly, the laser light LSR that has passed through the substrate 10 is absorbed by the first insulating film 13b. The absorption of the laser light LSR causes the SiN component in the first insulating film 13b to be thermally decomposed in a manner shown in the following reaction formula, for example.
SiN→Si+(½)N2↑
Consequently, as shown in
After that, as shown in
In the method for manufacturing the light-emitting device 111, there is no limit to the thickness of the first insulating film 13, so that the semiconductor layer 5 can be reliably protected by the first insulating film 13. In addition, at the laser lift off, the substrate 10 can be removed easily without allowing the first insulating film 13 to adhere to the substrate 10.
Subsequently, description will be given of a method for manufacturing a light-emitting device according to a second embodiment.
In this embodiment, the processes from the formation of the first semiconductor layer 11 and the second semiconductor layer 12 until the formation of the first insulating film 13 are similar to those shown in
In this embodiment, after the formation of the first insulating film 13, the first insulating film 13 formed in the bottom portions of the grooves 8 are removed as shown in
The first insulating film 13 in the bottom portions of the grooves 8 is removed in the same process where openings for forming the n-side electrode 14 and the p-side electrode 15 are formed. The first insulating film 13 is selectively removed by etching with, for example, a solution of hydrofluoric acid. The first insulating film 13 in the bottom portions of the grooves 8 is removed until the first main surface 10a of the substrate 10 is exposed.
Subsequently, as shown in
After the formation of the second insulating film 16, the opening 16a that reaches the n-side electrode 14 and the opening 16b that reaches the p-side electrode 15 are formed in the second insulating film 16 as shown in
After that, the formation of the n-side metal pillar 19 and the p-side metal pillar 20, the formation of the resin 26, and the removal of the substrate 10 by the laser lift off are performed in a similar manner to those in the case illustrated in
In this embodiment, since the first insulating film 13 in the bottom portions of the grooves 8 is removed in advance, the first insulating film 13 does not adhere to the substrate 10 at the laser lift off, and thus the substrate 10 is removed easily.
After the removal of the substrate 10, the lower surface 5c of the semiconductor layer 5 and a lower surface 16c of the second insulating film 16 appear as flat surfaces.
After that, as shown in
According to the method for manufacturing the light-emitting device 120, the first insulating film 13 being in contact with the substrate 10 has been removed in advance, so that the substrate 10 can be removed from the lower surface Sc of the semiconductor layer 5 easily at the laser lift off.
Subsequently, description will be given of a method for manufacturing a light-emitting device according to a third embodiment.
In this embodiment, the processes from the formation of the first semiconductor layer 11 and the second semiconductor layer 12 until the formation of the first insulating film 13 are similar to those shown in
In this embodiment, after the formation of the first insulating film 13, the first insulating film 13 formed in the bottom portions of the grooves 8 is removed as shown in
In this embodiment, the first insulating film 13 is made of silicon oxide (SiO2). In the portions other than the thinly-formed portions 13c, the thickness of the first insulating film 13 is equal to or larger than the wavelength of the laser light LSR. In contrast, the thickness of each of the thinly-formed portions 13c is smaller than the wavelength of the laser light LSR. To put it differently, only parts (the portions 13c) of the first insulating film 13 formed on the side surfaces 5b of the semiconductor layer 5 have a thickness that is smaller than the wavelength of the laser light LSR.
In this embodiment, as shown in
Subsequently, as shown in
After the formation of the second insulating film 16, the opening 16a that reaches the n-side electrode 14 and the opening 16b that reaches the p-side electrode 15 are formed in the second insulating film 16 as shown in
After that, the formation of the n-side metal pillar 19 and the p-side metal pillar 20, the formation of the resin 26, and the removal of the substrate 10 by the laser lift off are performed in a similar manner to those in the case illustrated in
In this embodiment, since each of the portions 13c of the first insulating film 13 near the bottom portions of the grooves 8 is formed to have a thickness that is smaller than the wavelength of the laser light LSR, the advancing of the laser light LSR thrown upon from the side of the lower surface 5c of the semiconductor layer 5 is suppressed by the portions 13c.
Accordingly, the degradation of the semiconductor layer 5, especially, the degradation of the light-emitting layer of the second semiconductor layer 12 is avoided. Consequently, stable light-emitting characteristics can be maintained. In addition, removal of the first insulating film 13 is prevented from occurring at the interface between each of the side surfaces 5b of the semiconductor layer 5 and the first insulating film 13.
In addition, the effects of the irradiation of the laser light LSR on the second insulating film 16 that is in contact with the first insulating film 13 near the side surfaces 5b, such as the melting of the second insulating film 16, is reduced. Consequently, the lowering of the reliability can be suppressed. In addition, the first insulating film 13 in the bottom portions of the grooves 8 has been removed in advance, so that the first insulating film 13 does not adhere to the substrate 10 at the laser lift off, and thus the substrate 10 is removed easily.
After the removal of the substrate 10, the lower surface Sc of the semiconductor layer 5 and a bottom surface 16c of the second insulating film 16 appear as flat surfaces.
After that, as shown in
In this embodiment, the portions 13c that are thinner than the wavelength of the laser light LSR are provided near the bottom portions of the grooves 8, but similar effects can be obtained if such portions 13c are provided between the first main surface 10a of the substrate 10 and the light-emitting layer of the second semiconductor layer 12.
Subsequently, description will be given of a light-emitting device according to a fourth embodiment.
A light-emitting device 110 according to this embodiment includes: the semiconductor layer 5 including a light-emitting layer, and formed by using the substrate 10 as a supporting body, the substrate 10 being removed from the semiconductor layer 5 by irradiation of the laser-light performed after the formation of the semiconductor layer 5; the n-side electrode 14 (first electrode portion) and the p-side electrode 15 (second to electrode portion) provided on the top surface 5a of the semiconductor layer 5 on the opposite side to the lower surface 5c that are irradiated with the laser light; the first insulating film 13 covering at least the side surfaces 5b of the semiconductor layer 5; and the second insulating film 16 is covering the first insulating film 13. The second insulating film (irrespective of silicon nitride or a resin) and the semiconductor layer 5 absorb the laser light. Alternatively, both the band-gap energy of the second insulating film 16 and the band-gap energy of the semiconductor layer 5 are made smaller than the energy of the laser light described above.
In addition, the portions of the first insulating film 13 covering the side surfaces 5b of the semiconductor layer 5 suppress the advancing of the laser light so that the laser light can be prevented from reaching the light-emitting layer in the side surfaces 5b from the lower surface 5c of the semiconductor layer 5.
In the light-emitting device 110, the first insulating film 13 is provided on the side surfaces 5b of the semiconductor layer 5 to have the thickness t smaller than the wavelength of the laser light LSR thrown upon at the laser lift off to remove the substrate 10 from the semiconductor layer 5.
The laser light to be used is, for example, light of ArF laser (wavelength: 193 nm), light of KrF laser (wavelength: 248 nm), light of XeCl laser (wavelength: 308 nm), or light of XeF laser (wavelength: 353 nm). The first insulating film 13 is formed to have the thickness t smaller than the wavelength of the laser light that is to be used actually.
According to the light-emitting device 110 that has the first insulating film 13 with the above-described thickness, the laser light LSR thrown upon at the laser lift off does not enter the first insulating film 13 formed on the side surfaces 5b of the semiconductor layer 5. Accordingly, the degradation of the semiconductor layer 5, especially, that of the light-emitting layer of the second semiconductor layer 12, is avoided. Consequently, stable light-emitting characteristics can be maintained. In addition, removal of the first insulating film 13 is prevented from occurring at the interface between each of the side surfaces 5b of the semiconductor layer 5 and the first insulating film 13. In addition, the adverse effects of the irradiation of the laser light LSR on the second insulating film 16 that is in contact with the first insulating film 13 near the side surfaces 5b, such as the melting of the second insulating film 16, is reduced. Consequently, the lowering of the reliability is suppressed.
The light-emitting device 110 according to this embodiment is formed collectively in a wafer configuration by the above-described manufacturing method according to the first embodiment. The semiconductor layer 5 includes the first semiconductor layer 11 and the second semiconductor layer 12. The first semiconductor layer 11 is, for example, an n type GaN layer, and serves as a current pathway in the lateral direction. The conductivity type of the first semiconductor layer 11 is not limited to n type but may be p type.
In the light-emitting device 110, light is emitted out mainly from the first main surface 11a of the first semiconductor layer 11 (i.e., the lower surface 5c of the semiconductor layer 5). The second semiconductor layer 12 is provided on the second main surface 11b of the first semiconductor layer 11 on the opposite side to the first main surface 11a.
The second semiconductor layer 12 has a laminate structure of multiple semiconductor layers, each of the semiconductor layers including a light-emitting layer (active layer).
An n type GaN layer 31 is provided on the second main surface 11b of the first semiconductor layer 11. A light-emitting layer 33 is provided on the GaN layer 31. The light-emitting layer 33 has a multiple quantum well structure containing, for example, InGaN. A p type GaN layer 34 is provided on the light-emitting layer 33.
As shown in
The bottom surface of the recessed portion is the second main surface 11b of the first semiconductor layer 11. The n-side electrode 14 is provided on the second main surface 11b of the recessed portion as a first electrode.
The p-side electrode 15 is provided on the opposite surface of the second semiconductor layer 12 to the surface being in contact with the first semiconductor layer as a second electrode.
The second main surface 11b of the first semiconductor layer 11 is covered with the first insulating film 13 made, for example, of silicon oxide. The portions of the first insulating film 13 covering the side surfaces 5b of the semiconductor layer 5 reach the first main surface 11a of the first semiconductor layer 11. The n-side electrode 14 and the p-side electrode 15 are exposed from the first insulating film 13. The n-side electrode 14 and the p-side electrode 15 are insulated from each other by the first insulating film 13, and thus are provided as electrodes that are electrically independent of each other. In addition, the first insulating film 13 covers also the side surfaces of the projected portion including the second semiconductor layer 12.
The second insulating film 16 is provided on the second main surface 11b side so as to cover the first insulating film 13, a part of the n-side electrode 14, and a part of the p-side electrode 15. The second insulating film 16 is, for example, made of silicon oxide or a resin.
The opposite surface of the second insulating film 16 to the first semiconductor layer 11 and the second semiconductor layer 12 is flattened, and the n-side interconnection 17 as a first interconnection and the p-side interconnection 18 as a second interconnection are provided on the flattened surface.
The n-side interconnection 17 is also provided in the opening 16a, which is formed in the second insulating film 16 so as to reach the n-side electrode 14, and the n-side interconnection 17 is electrically connected to the n-side electrode 14. The p-side interconnection 18 is also provided in the opening 16b, which is formed in the second insulating film 16 so as to reach the p-side electrode 15, and the p-side interconnection 18 is electrically connected to the p-side electrode 15.
All of the n-side electrode 14, the p-side electrode 15, the n-side interconnection 17, and the p-side interconnection 18 are provided on the second main surface 11b side of the first semiconductor layer and form interconnect layers to supply a current to the light-emitting layer.
The n-side metal pillar 19 is provided on the opposite surface of the n-side interconnection 17 to the n-side electrode 14 as a first metal pillar. The p-side metal pillar 20 is provided on the opposite surface of the p-side interconnection 18 as a second metal pillar. The resin (third insulating film) 26 covers the portion around the n-side metal pillar 19, the portion around the p-side metal pillar 20, the n-side interconnection 17, and the p-side interconnection 18. In addition, the resin 26 covers side surfaces 11c of the first semiconductor layer 11 as well, and thus the side surfaces 11c of the first semiconductor layer 11 are protected by the resin 26.
The first semiconductor layer 11 is electrically connected to the n-side metal pillar 19 via the n-side electrode 14 and the n-side interconnection 17. The second semiconductor layer 12 is electrically connected to the p-side metal pillar 20 via the p-side electrode 15 and the p-side interconnection 18. The external terminals 25, such as solder balls or metal bumps, are provided on the lower end surfaces, exposed from the resin 26, of the n-side metal pillar 19 and of the p-side metal pillar 20. The light-emitting device 110 is electrically connected to an external circuit through the external terminals 25.
The thickness of the n-side metal pillar 19 (the thickness in the vertical direction of
According to the structure of this embodiment, even if the semiconductor layer 5 is thin, a certain mechanical strength can be secured by making the n-side metal pillar 19, the p-side metal pillar 20, and the resin 26 thicken In addition, when the light-emitting device 110 is mounted on a circuit board or the like, the stress applied to the semiconductor layer 5 through the external terminals 25 can be absorbed by the n-side metal pillar 19 and the p-side metal pillar 20. Accordingly, the stress applied to the semiconductor layer 5 can be reduced. The resin 26 to reinforce the n-side metal pillar 19 and the p-side metal pillar 20 is preferably made of a resin whose coefficient of thermal expansion is equal to, or close to, that of the circuit board or the like. Such a resin 26 is, for example, an epoxy resin, a silicone resin, or a fluorine resin. In addition, the resin 26 is colored in black, for example. The resin 26 thus prevents the internal light from leaking out and prevents unnecessary external light from entering.
The n-side interconnection 17, the p-side interconnection 18, the n-side metal pillar 19, and the p-side metal pillar 20 are made, for example, of copper, gold, nickel, or silver. Of these materials, copper is preferable because of its favorable thermal conductivity, its high electromigration resistance, and its excellent adherence to the insulating films.
A phosphor layer 27 is provided on the light-emitting surface of the light-emitting device 110 when necessary. For example, if the light-emitting' layer emits blue light and the blue light is emitted from the light-emitting device 110 as it is, no such phosphor layer 27 is necessary. In contrast, if the light-emitting device 110 emits white light or the like, that is, light of a wavelength different from that of the light emitted by the light-emitting layer, the phosphor layer 27 is provided which contains phosphors absorbing the wavelength of the light emitted by the light-emitting layer and thus converting wavelength of the light emitted by the light-emitting layer into the wavelength of the light to be emitted from the light-emitting device 110.
The light-emitting surface of the light-emitting device 110 may be provided with a lens (not illustrated) when necessary. Lenses of various shapes, such as convex lenses, concave lenses, aspheric lenses, may be used. The number and the positions of the lenses to be provided may be determined appropriately.
In the light-emitting device 110 according to this embodiment, the degradation of the semiconductor layer 5 is avoided, and removal of the first insulating film 13, the melting of the second insulating film 16, and the like are reduced. Accordingly, light-emitting characteristics of the light-emitting device 110 is secured and the lowering of the reliability of the light-emitting device 110 is reduced.
Subsequently, description will be given of a light-emitting device according to a fifth embodiment.
As shown in
The light-emitting device 111 according to the fifth embodiment is formed collectively in a wafer configuration by another example of the above-described manufacturing method according to the first embodiment. If, for example, light of KrF laser (wavelength: 248 nm) is used as the laser light LSR at the laser lift off, the first insulating film 13 is made, for example, of silicon nitride (SiN). In other cases, the first insulating film 13 is made of a material containing a nitride. If the band-gap energy of the first insulating film 13 is smaller than the energy of the laser light LSR, the transmissibility of the laser light LSR drops significantly. Consequently, the entry, into the first insulating film 13, of the laser light LSR thrown upon at the laser lift off is suppressed.
In the light-emitting device 111 according to this embodiment, the degradation of the semiconductor layer 5 is avoided, and removal of the first insulating film 13, the melting of the second insulating film 16, and the like are reduced. Accordingly, light-emitting characteristics of the light-emitting device 111 is secured and the lowering of the reliability of the light-emitting device 111 is reduced.
Subsequently, description will be given of a light-emitting device according to a sixth embodiment.
As shown in
The light-emitting device 120 according to the sixth embodiment is formed collectively in a wafer configuration by the above-described manufacturing method according to the second embodiment.
The first insulating film 13 is made, for example, of silicon oxide (SiO2) or silicon nitride (SiN). If the first insulating film 13 is made of silicon oxide (SiO2), the first insulating film 13 is formed to have the thickness t smaller than the wavelength of the laser light LSR. If the first insulating film 13 is made of silicon nitride (SiN), there is no limit to the thickness t.
In the light-emitting device 120 according to the sixth embodiment, portions of the first insulating film 13 in the surrounding areas of the semiconductor layer 5 are removed, so that the first insulating film 13 does not adhere to the substrate 10 at the laser lift off, and the substrate 10 is thus removed easily.
In addition, after the removal of the substrate 10, the lower surface Sc of the semiconductor layer 5′ and the lower surface 16c of the second insulating film 16 appear as flat surfaces.
Subsequently, description will be given of a light-emitting device according to a seventh embodiment.
As shown in
The light-emitting device 130 according to the seventh embodiment is formed collectively in a wafer configuration by the above-described manufacturing method according to the third embodiment.
Each of the thinner portions 13c of the first insulating film 13 is provided between the bottom surface 5c of the semiconductor layer 5 and the light-emitting layer provided in the second semiconductor layer 12. The thickness t1 of each of the portions 13c is smaller than the wavelength of the laser light LSR. In contrast, the other portions of the first insulating film 13 have a thickness t2 that is equal to or larger than the wavelength of the laser light LSR.
In this embodiment, since the portions 13c are formed so thinly that the thickness of each of the portions 13c is smaller than the wavelength of the laser light LSR, the advancing of the laser light LSR thrown upon from the side of the lower surface 5c of the semiconductor layer 5 is suppressed by the portions 13c. Accordingly, the degradation of the semiconductor layer 5 is avoided, and removal of the first insulating film 13, the melting of the second insulating film 16, and the like are reduced. Accordingly, light-emitting characteristics of the light-emitting device 130 is secured and the lowering of the reliability of the light-emitting device 130 is reduced.
Subsequently, description will be given of a light-emitting device according to a eighth embodiment.
In this embodiment, the processes from the formation of the first semiconductor layer 11 and the second semiconductor layer 12 until the formation of the first insulating film 13 may be similar to those shown in
In this embodiment, as shown in
Subsequently, as shown in
After the formation of the second insulating film 16, the opening 16a that reaches the n-side electrode 14 and the opening 16b that reaches the p-side electrode 15 are formed in the second insulating film 16 as shown in
After that, the formation of the n-side metal pillar 19 and the p-side metal pillar 20, the formation of the resin 26, and the removal of the substrate 10 by the laser lift off are performed in a similar manner to those in the case illustrated in
According to the embodiments thus far described, the substrate 10 can be removed from the lower surface 5c of the semiconductor layer 5 easily at the laser lift off.
In the light-emitting device 140, the first insulating film 13 is made of a material (e.g., silicon nitride) that has smaller band-gap energy than the energy of the laser light LSR. In the light-emitting device 140, the second insulating film 16 is made of a material (e.g., polyimide) that absorbs the laser light LSR.
When using the resin such as the polyimide for the second insulating film 16, it becomes easy to ease the stress added between the substrate 10 and the semiconductor layer 5 at the laser lift off. In the laser lift off, the interface and its circumference of the substrate 10 and semiconductor layer 5 are heated by laser-light irradiation. The distortion stress by heating tends to join the interface. When using the resin such as the polyimide for the second insulating film 16, the distortion stress can be absorbed by the second insulating film 16, and the influence of the distortion stress to the semiconductor layer 5 can be reduced.
In this embodiment, since the material (e.g., silicon is nitride) that has smaller band-gap energy than the energy of the laser light LSR is used for the first insulating film 13, a ablation of the second insulating film 16 (a resin such as the polyimide) by laser-light irradiation at the laser lift off can be prevented.
As shown in
In contrast, as shown in
Accordingly, When using the resin such as the polyimide for the second insulating film 16, since the material (e.g., silicon nitride) that has smaller band-gap energy than the energy of the laser light LSR is used for the first insulating film 13, the ablation of the second insulating film 16 can be prevented, and the decrease in the emission intensity can be prevented.
Here, description will be given of a irradiated region of the laser light LSR.
In the manufacturing of the light-emitting devices 110, 111, 120, 130, and 140 thus far described, a irradiated region of the laser light LSR is moved sequentially at the laser lift off.
The grooves 8 are formed in a lattice shape on the substrate 10. The semiconductor layer 5 is provided between adjacent grooves 8. Plurality of the semiconductor layers 5 are separated by the grooves 8 on the substrate 10.
At the laser lift off, a rectangular region R which encloses at least one of the plurality of the semiconductor layers 5 is irradiated with the laser light LSR. In
At the laser lift off, the irradiation of the laser light LSR to the region R is performed moving sequentially. For example, in
For example, when the irradiation of the laser light LSR for the row ends, the irradiation of the laser light LSR for the following row is performed similarly. A distance S is formed between adjacent regions R. Here, the distance S is also a portion which the laser light LSR is not irradiated besides a portion with few amounts of irradiation of accumulation of the laser light LSR than the region R. The distance S is provided between the adjacent regions R, the adjacent regions R adjoin at X and Y axially respectively to the region R.
As shown in
According to the embodiments thus far described, in the manufacturing of the light-emitting devices 110, 111, 120, 130, and 140 employing the laser lift off, the advancing of the laser light LSR within the first insulating film 13 that cover the side surfaces 5b of the semiconductor layer 5 can be suppressed. Accordingly, effects of the irradiation of the laser light LSR on such as the degradation of the semiconductor layer 5, the removal of the first insulating film 13, and the melting of the second insulating film 16, can be reduced. Consequently, improvements in the operational stability and the reliability of the light-emitting devices 110, 111, 120, 130, and 140 can be accomplished.
Hereinabove, some embodiments have been described with reference to specific examples. The above-described embodiments are not limited thereto. For example, from the aforementioned embodiments and variations, those skilled in the art may make different modes of embodiments by providing any additional constituent element or by omitting any constituent element, based on modified design, or by appropriately combining characteristic features in the above embodiments. These different modes of embodiments are also included in the scope of the invention as long as the modes retain the gist of the invention. In addition, those skilled in the art may make various kinds of changes in design concerning the substrate, the semiconductor layers, the electrodes, the interconnections, the metal pillars, the insulating films, the material of the resin, the size, the shape, the layout, and the like. Those thus changed are also included in the scope of the invention unless the changes depart from the gist of the invention.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-127506 | Jun 2010 | JP | national |
| 2011-039997 | Feb 2011 | JP | national |
This application is a continuation-in-part of and claims the benefit of priority under 35 U.S.C. .sctn.120 from U.S. Ser. No. 12/888,754 filed Sep. 23, 2010, and claims the benefit of priority under 35 U.S.C. .sctn.119 from the prior Japanese Patent Application No. 2010-127506, filed on Jun. 3, 2010 and the prior Japanese Patent Application No. 2011-039997, filed on Feb. 25, 2011; the entire contents of each of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12888754 | Sep 2010 | US |
| Child | 13173073 | US |
