JP4600737B2 - Light emitting element - Google Patents

Description

  The present invention relates to a light emitting element.

JP 2003-347578 A

  As a result of many years of progress in materials and element structures used in light-emitting elements such as light-emitting diodes and semiconductor lasers, the photoelectric conversion efficiency inside the elements is gradually approaching the theoretical limit. Accordingly, when an element with higher luminance is to be obtained, the light extraction efficiency from the element is extremely important. For example, in a light emitting device having a light emitting layer portion formed of AlGaInP mixed crystal, a thin AlGaInP (or GaInP) active layer is sandwiched between an n-type AlGaInP cladding layer and a p-type AlGaInP cladding layer having a larger band gap. By adopting a sandwiched double hetero structure, a high-luminance element can be realized. Such an AlGaInP double heterostructure can be formed by epitaxially growing each layer of an AlGaInP mixed crystal on a GaAs single crystal substrate by utilizing the lattice matching of the AlGaInP mixed crystal with GaAs. When this is used as a light emitting element, a GaAs single crystal substrate is usually used as an element substrate as it is. However, since the AlGaInP mixed crystal constituting the light emitting layer has a larger band gap than GaAs, the emitted light is absorbed by the GaAs substrate and it is difficult to obtain sufficient light extraction efficiency.

Therefore, Patent Document 1 discloses a light emitting element chip structure in which a GaAs substrate outer peripheral portion on the interface side in contact with a semiconductor laminated portion including a light emitting layer forming portion is partially omitted while leaving a GaAs substrate. . The said document, by emitting light from the missing portion to the outside, it is possible to cheat reducing the luminous flux that is absorbed in the substrate, that can increase the external quantum efficiency is touted.

  However, in the element structure of Patent Document 1, the exposed back surface (second main surface) of the semiconductor stacked portion across the notch is opposed to the absorptive GaAs substrate, and is emitted to the notch. A large amount of the emitted luminous flux is still absorbed by the GaAs substrate, and the external quantum efficiency cannot be increased as expected.

  An object of the present invention is to adopt a structure in which an absorptive substrate is left on the back side of a light emitting layer part through a notch part, and to take out the luminous flux emitted to the notch part side An object of the present invention is to provide a light-emitting element that can further enhance the brightness.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-described problems, the light-emitting element of the present invention includes:
A main compound semiconductor layer having a light emitting layer portion and having a main light extraction surface formed on its first main surface side; and a light-absorbing base semiconductor layer located on the second main surface side of the main compound semiconductor layer; The second main surface of the base semiconductor layer is bonded to the metal stage via the metal paste layer, and
The base semiconductor layer so that at least a part of the portion directly below the main light extraction surface becomes a notch target portion, and a remaining portion resulting from the notch includes at least a portion of the portion directly below the light extraction side electrode. A notch is formed in the
The base semiconductor layer is integrated with the main body forming the inner side surface of the notch and the second main surface side end of the main body, and projects outward from the peripheral side surface of the main body. And a second main surface of the hook-shaped portion is bonded to the metal stage by a metal paste layer, and the metal paste layer is in the second main surface in-plane direction of the hook-shaped portion, circumferential portion protruding outside the side surface of the collar-shaped portion, Ri Na to form a wraparound overlaid portion around to the first main surface side of the collar-like portion through the peripheral side surface, the height of the flange portion There are at 10μm or 60μm or less, the main body portion, the shaft cross-sectional area and wherein Rukoto such form the peripheral side surface is constricted shape so that the minimum height direction intermediate portion.

  The “light extraction surface” of the element is the surface of the element from which the emitted light beam can be extracted to the outside. The “main light extraction surface” is formed on the first main surface of the main compound semiconductor layer. Refers to the light extraction surface. In addition to the main light extraction surface, a side surface of the main compound semiconductor layer, a bottom surface of a notch formed in the second main surface of the compound semiconductor layer, and the like can constitute the light extraction surface. In addition, the “main compound semiconductor layer” refers to a portion including the light emitting layer portion when the compound semiconductor stack including the light emitting layer portion is bisected in the thickness direction by a plane including the bottom surface of the cutout portion. Say.

In the light emitting device of the present invention, the light-absorbing base semiconductor layer is integrated with the main body part forming the inner surface of the notch part and the second main surface side end part of the main body part. The second main surface of the bowl-shaped part is bonded to the metal stage by a metal paste layer. In the inward direction of the second main surface of the bowl-shaped portion, the metal paste layer has a portion that protrudes outside the circumferential side surface of the bowl-shaped portion through the circumferential side surface on the first main surface side of the bowl-shaped portion. A wraparound portion that wraps around is formed. By this structure, the following effects are achieved.
(1) The base semiconductor layer is cut out at a portion of the second main surface of the main compound semiconductor layer that is a region immediately below the main light extraction surface, so that the luminous flux directed toward the portion is cut out more efficiently. Thus, the light extraction efficiency can be greatly improved. And the 2nd main surface of the main compound semiconductor layer exposed by the notch part opposes the 1st main surface of the bowl-shaped part of a base semiconductor layer, but this wraps around and forms a metal paste layer with high reflectance Therefore, the luminous flux emitted to the notch portion side can be reflected on the surface of the wrap-around built-up portion even on the first main surface side of the bowl-shaped portion, and the light extraction efficiency can be improved. it can.
(2) When the base semiconductor layer is bonded onto the metal stage via the metal paste layer, the bottom surface (second main surface) of the base semiconductor layer is formed by placing the metal paste layer somewhat excessively and pressing the base semiconductor layer. The metal paste layer that oozes out from the peripheral edge of the metal crawls up the side surface of the bowl-shaped part, and then wraps around the upper surface side of the bowl-shaped part, so that a desired wrap-around built-up part can be easily formed. (3) Although related to (2), the bottom area of the base semiconductor layer increases due to the formation of the bowl-shaped portion, and the excessively deposited metal paste layer is greatly expanded so as to collapse in the bowl-shaped portion. Oozes out of the bowl with a relatively large area. Therefore, the swelled metal paste layer is reduced in height by the amount corresponding to the increase in the bottom area, and forms a wraparound portion as a notch absorption space above the bowl-shaped portion. In addition, the metal paste layer crawls up the side surface of the base semiconductor layer to reach the side surface of the light emitting layer portion, and it is difficult to cause a problem that causes a short circuit.
(4) Since the bottom area of the base semiconductor layer is increased due to the formation of the bowl-shaped portion, the adhesion area by the metal paste layer is also increased, and the adhesion strength of the element chip to the metal stage can be increased. Moreover, since the wraparound portion has a structure of pressing down the upper surface side of the bowl-shaped portion, this also contributes to the improvement of the adhesive strength.

  In addition, when the structure which covers an element chip with a mold part on a metal stage with a metal paste layer, the following effect is further achieved. That is, the notch portion is filled with the polymer mold material, but when the hook-like portion is provided on the second main surface side of the base semiconductor layer, the polymer mold material filling the notch portion expands. Since the expansion stress acts in the direction in which the base semiconductor layer is pressed against the metal paste layer in the bowl-shaped portion, it is possible to effectively suppress problems such as the element chip floating and peeling off from the metal paste layer. Note that at least a part of the mold part can be made of an epoxy resin. Epoxy resin has a relatively large refractive index, and thus has a particularly remarkable effect of improving the light extraction efficiency. However, since the coefficient of thermal expansion is also high, problems such as peeling of the element chip as described above are likely to occur. However, even when an epoxy resin having a high coefficient of thermal expansion is employed as the molding material, the light extraction improvement effect can be enjoyed without any problem while effectively suppressing defects such as element chip peeling. The effect is particularly remarkable when adopting a configuration in which the notch is filled with an epoxy resin. In addition, the whole mold part may be comprised with the epoxy resin, and only one part may be comprised with the epoxy resin.

  In order to prevent the metal paste from creeping up on the side surface of the light emitting layer part, it is desirable that the wrap-around built-up part is configured to cover the main body part of the base semiconductor layer up to a midway position in the height direction. Moreover, in order to obtain such a structure specifically, it is desirable to set the height of the main body portion to be larger than the height of the built-up portion.

  On the other hand, in order to reliably form the wraparound built-up portion that wraps around the second main surface (upper surface) of the bowl-shaped portion, the height of the main body portion of the base semiconductor layer is set larger than the height of the bowl-shaped portion. It is desirable. In this case, more specifically, the height of the bowl-shaped portion is preferably set within a range of 10 μm to 60 μm. If the height of the hook-shaped portion is less than 10 μm, it becomes difficult to stably form the hook-shaped portion by etching or the like. On the other hand, if the height of the bowl-shaped portion exceeds 60 μm, it may be difficult to reliably form the wraparound portion.

  Moreover, it is desirable to set the protrusion dimension of the bowl-shaped part from the peripheral side surface of the main body part to 5 μm or more. When the projecting dimension is less than 5 μm, the formation area of the wrap-around build-up portion becomes insufficient, and the effects (1) to (4) described above cannot be achieved sufficiently. In consideration of forming a bowl-shaped part by combining dicing and etching of a semiconductor wafer, whether the outline of the bowl-shaped part overlaps with or falls inside the compound semiconductor layer It must be either. In this case, the axial cross-sectional area (value at the minimum position) of the main body portion is the entire second main surface of the base semiconductor layer including the bowl-shaped portion so that the main body portion of the base semiconductor layer is not excessively thinned. It is desirable to determine the upper limit of the projecting dimension so as to be 50% or more of the area.

  The main body portion of the base semiconductor layer can be configured such that the peripheral side surface has a constricted shape so that the axial cross-sectional area is minimized at an intermediate portion in the height direction. By making the side surface of the main body constricted as described above, the expansion stress of the mold material filled in the notch can be distributed in various directions along the curved surface, making it less likely to cause device chip peeling and the like. be able to.

  Next, the light emitting device of the present invention can be configured as follows. That is, the main compound semiconductor layer is epitaxially grown on the first main surface of the light-absorbing compound semiconductor substrate, a partial region of the first main surface of the main compound semiconductor layer is a main light extraction surface, and a light emission driving voltage is applied to the light emitting layer portion. A light extraction-side electrode for applying a voltage is formed so as to cover a part of the first main surface of the main compound semiconductor layer. Then, at least a part of the portion directly below the main light extraction surface is a notch target portion, and the residual substrate portion generated as a result of the notch includes at least a portion of the portion directly below the light extraction side electrode. A cutout portion is formed in the absorbent compound semiconductor substrate, and the residual substrate portion forms a base semiconductor layer. When the light emitting layer portion is made of, for example, AlGaInP, a GaAs substrate can be used as the light absorbing compound semiconductor substrate (and thus the residual substrate portion) used for the epitaxial growth.

  In this configuration, the light-absorbing compound semiconductor substrate used for the epitaxial growth of the light-emitting layer portion (including the main compound semiconductor layer) is not removed after the light-emitting layer portion has been grown, but is formed directly below the main light extraction surface. At least a part is a part to be cut out, and the remaining substrate part generated as a result of the notch is cut out so as to include at least a part of the part directly under the light extraction side electrode. The compound semiconductor substrate for growth acting as a light absorbing portion is cut out at a portion of the second main surface of the main compound semiconductor layer that is immediately below the main light extraction surface, so that the emitted light flux toward the portion is also externally The light extraction efficiency can be greatly increased. On the other hand, a part of the substrate is left as a residual substrate portion in the region directly under the light extraction side electrode. Although the residual substrate portion has a light absorption function, even if reflected light is generated in the region immediately below the light extraction side electrode, it is eventually blocked by the light extraction side electrode, so that a part of the substrate remains in this portion. There is little real harm. And by leaving a part of the light-absorbing compound semiconductor substrate as a residual substrate part in the region, the function of imparting rigidity to the light emitting layer part is made without making the influence of light absorption by the residual substrate part so remarkable. You can carry it.

  If the cutout portion surrounds the portion immediately below the light extraction side electrode and is formed along the peripheral portion thereof, the luminous flux extracted using the cutout portion can be further increased. Further, if an auxiliary current diffusion layer made of a compound semiconductor is provided between the residual substrate portion and the light emitting layer portion, the luminous flux extracted from the bottom surface of the notch can be further increased. When forming the notch, if the thickness is sufficiently small (for example, 20 nm or less), a part of the light-absorbing compound semiconductor substrate may remain on the bottom of the notch. However, from the viewpoint of increasing the reflectivity as much as possible, the light-absorbing compound semiconductor derived from the substrate does not remain at the bottom of the cutout portion as much as possible, that is, the cutout portion is a light-absorbing compound semiconductor substrate. It is desirable to expose the second main surface of the main compound semiconductor layer (having a smaller light absorption than the substrate) in the notch portion.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The light emitting device 100 of FIG. 1 has a device chip 100C in which a main compound semiconductor layer 40 having a light emitting layer portion 24 is epitaxially grown on a first main surface of a light absorbing compound semiconductor substrate 10 (see FIG. 3). FIG. 2 is an enlarged view of the element chip 100 </ b> C, in which a main light extraction surface EA is formed on the first main surface side of the main compound semiconductor layer 40 and light for applying a light emission driving voltage to the light emitting layer portion 24. The extraction-side electrode 9 is formed so as to cover a part of the first main surface of the main compound semiconductor layer 40 (specifically, the remaining area of the main light extraction surface EA). The light-absorbing compound semiconductor substrate 10 has a notch 1j formed by notching a peripheral edge except for a portion directly below the light extraction side electrode 9, and a substrate portion left on the periphery of the notch 1j is formed. A residual substrate portion (base semiconductor layer) 1 is formed. In FIG. 1, the transparent thick film semiconductor layer 20 and the light emitting layer portion 24 belong to the main compound semiconductor layer 40, and the residual substrate portion 1 does not belong to the main compound semiconductor layer 40.

The light emitting layer portion 24 includes the active layer 5 made of a non-doped (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 0.55, 0.45 ≦ y ≦ 0.55) mixed crystal. , the first-conductivity-type cladding layer, in this embodiment the p-type cladding layer 6 made of p-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1), wherein the first conductivity type the second-conductivity-type cladding layer different from the clad layer, in this embodiment interposed by an n-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1) n-type cladding layer 4 made of According to the composition of the active layer 5, the emission wavelength can be adjusted in the green to red region (the emission wavelength (peak emission wavelength) is 550 nm or more and 670 nm or less). In the light emitting device 100, the p-type AlGaInP clad layer 6 is disposed on the light extraction side electrode 9, and the n-type AlGaInP clad layer 4 is disposed on the residual substrate portion 1 side. Accordingly, the light extraction side electrode 9 is positive in the energization polarity. The term “non-dope” as used herein means “does not actively add a dopant”, and contains a dopant component inevitably mixed in a normal manufacturing process (for example, 10 ¹³ to 10 ¹⁶ / cm 3). It is not excluded that the upper limit is about ³ ). The residual substrate portion 1 is made of GaAs single crystal.

In the main compound semiconductor layer 40, a transparent thick film semiconductor layer 20 made of GaP (or GaAsP or AlGaAs may be used) is formed on the first main surface of the light emitting layer portion 24. The aforementioned light extraction side electrode 9 (for example, an Au electrode) is formed substantially at the center of one main surface. A region around the light extraction side electrode 9 on the first main surface of the transparent thick film semiconductor layer 20 forms a main light extraction surface EA. The transparent thick film semiconductor layer 20 has an effective carrier concentration (and therefore a p-type dopant concentration) that is high enough to form an ohmic contact with the light extraction side electrode 9 (for example, equal to or higher than that of the p-type cladding layer 6). And 2 × 10 ¹⁸ / cm ³ or less). The transparent thick film semiconductor layer 20 is formed in a thick film of, for example, 10 μm or more and 200 μm or less (preferably 40 μm or more and 200 μm or less), thereby increasing the extracted light flux from the layer side surface 20S and increasing the brightness of the entire light emitting element (integrating sphere It also plays a role of increasing brightness. Further, by forming the transparent thick film semiconductor layer 20 with a III-V group compound semiconductor having a band gap energy larger than the photon energy corresponding to the peak wavelength of the luminous flux from the light emitting layer portion 24, the Absorption is also suppressed. In addition, between the light extraction side electrode 9 and the transparent thick film semiconductor layer 20, the joining alloying layer 9a for reducing contact resistance of both is formed, for example using AuBe alloy etc.

  On the other hand, on the residual substrate portion (base semiconductor layer) 1 side, a notch 1j is formed through the residual substrate portion 1 in the thickness direction and exposed to the second main surface of the main compound semiconductor layer 40. Yes. In the present embodiment, the light absorbing compound semiconductor substrate and thus the residual substrate portion 1 is of n type.

  The luminous flux from the light emitting layer portion 24 can be taken out also from the cutout portion 1j. Specifically, the second main surface of the remaining substrate portion 1 is bonded onto the metal stage 52 that also serves as a reflecting member, and the emitted light beam taken out from the notch portion 1j is reflected on the metal stage 52. ing. On the second main surface of the remaining substrate portion 1, a bonding alloying layer 16 forming a back electrode portion is formed on the entire surface. The bonding alloyed layer 16 is composed of Au or Ag as a main component (50 mass% or more), and a contact containing an appropriate amount of an alloy component for taking ohmic contact according to the type and conductivity type of a semiconductor to be a contact destination. It is formed by forming a metal film on the semiconductor surface and then performing an alloying heat treatment (so-called sintering process). In the present embodiment, the bonding alloying layer 16 is formed using an AuGeNi alloy (for example, Ge: 15% by mass, Ni: 10% by mass, balance Au).

  As shown in FIG. 1, in the bonded alloyed layer 16, the residual substrate portion 1 is bonded onto a metal stage 52 via a metal paste layer (metal paste layer) 117. As a result, the light emitting layer portion 24 is electrically connected to the metal stage 52 through the metal paste layer 117 in the form of the remaining substrate portion 1 as a conduction path. The metal paste layer 117 is formed by applying a metal paste in which a metal powder such as Ag is dispersed in a vehicle made of a binding resin and a solvent and then drying the paste. On the other hand, the light extraction side electrode 9 is electrically connected to the conductor metal fitting 51 via a bonding wire 9w made of Au wire or the like. The conductor metal fitting 51 penetrates the metal stage 52 and extends to the back surface side to form a first energizing terminal 51a. On the other hand, a second energizing terminal 52 a is formed to protrude from the back side of the metal stage 52. A resin insulating ring 51 i is disposed between the conductor metal fitting 51 and the metal stage 52. A light emission driving voltage is applied to the light emitting layer portion 24 via the first energizing terminal 51a and the second energizing terminal 52a.

  The residual substrate portion 1 is integrated with a main body portion 1m that forms the inner side surface of the notch portion 1j, and an end portion on the second main surface side of the main body portion 1m, and is more outward than the peripheral side surface of the main body portion 1m. It has a protruding hook-shaped part 1g. The main body 1m and the bowl-shaped portion 1g are integrally formed of GaAs single crystal. The second main surface of the bowl-shaped portion 1 g is bonded to the metal stage 52 by the metal paste layer 117. The portion of the metal paste layer 117 that protrudes outside the peripheral side surface of the hook-shaped part 1g in the inward direction of the second main surface of the hook-shaped part 1g passes through the peripheral side surface of the first part of the hook-shaped part 1g. A wraparound portion 117m that wraps around the main surface is formed.

  On the metal stage 52, the element chip 100 </ b> C is covered with a metal paste layer 117 and a polymer mold material that is transparent to the luminous flux from the light emitting layer portion 24, here a mold portion 25 made of epoxy resin. ing. The mold part 25 is formed such that the notch part 1j of the element chip 100C is filled with a polymer mold material. In the present embodiment, the entire mold part 25 is made of epoxy resin, and as a result, the notch part 1j is also filled with epoxy resin.

  By forming the notched portion 1j in the remaining substrate portion 1, it becomes possible to more efficiently extract the luminous flux directed toward the portion from the notched portion 1j, and the light extraction efficiency can be greatly increased. Further, the second main surface of the main compound semiconductor layer 40 exposed by the notch portion 1j is opposed to the first main surface of the bowl-shaped portion 1g of the residual substrate portion 1, but this causes the metal paste layer 117 having a high reflectivity to be formed. Since it is covered with the surrounding wrap-around portion 117m, the luminous flux emitted toward the notch portion 1j can be reflected on the surface of the wrap-around portion 117m also on the first main surface side of the bowl-shaped portion 1g. The light extraction efficiency can be improved.

  As shown in FIG. 8, in the case of the element chip 100C ′ in which the hook-shaped portion 1g is not formed as described above, the metal paste layer 117 does not progress so much by only the main body portion 1m having a small bottom area and protrudes. The metal paste has a shape that rises significantly around the main body 1m, and the side surface of the light emitting layer 24 is likely to creep up. As shown in FIG. 8, this problem tends to occur when the element chip 100C 'is adhered to the application region of the metal paste layer 117 with a deviation from the center.

  However, as shown in FIG. 2, in the light emitting element chip 100C in which the hook-shaped portion 1g is formed, the bottom area of the residual substrate portion 1 is increased by the formation of the hook-shaped portion 1g, and the metal paste layer 117 is formed by the hook-shaped portion 1g. After being greatly expanded so as to be crushed, it oozes out of the bowl-shaped portion 1g in a relatively large area. Accordingly, the metal paste layer 117 that has exuded has a raised height reduced by an amount corresponding to an increase in the bottom area, and wraps around the notched portion 1j absorption space above the bowl-shaped portion 1g. Form. Thereby, the metal paste layer 117 scoops up the side surface of the residual substrate portion 1 and reaches the side surface of the light emitting layer portion 24, so that a problem that causes a short circuit or the like hardly occurs.

  The metal paste layer 117 oozing from the peripheral edge of the bottom surface (second main surface) of the residual substrate portion 1 crawls up the side surface of the bowl-shaped portion 1g and then wraps around the upper surface side of the bowl-shaped portion 1g. The part 117m will be formed. As the bottom area of the residual substrate portion 1 increases due to the formation of the bowl-shaped portion 1g, the adhesion area by the metal paste layer 117 increases, and the adhesion strength of the element chip to the metal stage 52 can be increased. In addition, since the wraparound portion 117m has a structure of pressing down the upper surface side of the bowl-shaped portion 1g, this also contributes to the improvement of the adhesive strength.

  The wraparound portion 117m covers the main body portion 1m of the residual substrate portion 1 up to a midway position in the height direction. Further, the height H of the main body 1m is set to be larger than the height U of the wraparound portion 117m. Furthermore, the height H of the main body 1m is set to be larger than the height t of the bowl-shaped portion 1g. Specifically, the height t of the bowl-shaped portion 1g is determined within a range of 10 μm to 60 μm. Further, the protrusion dimension Q from the peripheral side surface of the main body 1m of the bowl-shaped portion 1g is set to 5 μm or more. In the present embodiment, the main body portion 1m of the residual substrate portion 1 is configured such that the peripheral side surface has a constricted shape so that the axial cross-sectional area is minimized at the intermediate portion in the height direction. In this case, the protrusion dimension Q from the peripheral side surface of the main body 1m of the bowl-shaped portion 1g is measured with the position where the axial cross-sectional area is minimized as a base point.

  As shown in FIG. 1, in the element chip 100C in which the notch 1j is formed, when the epoxy resin filled in the notch 1j expands due to energization heat generation of the element chip 100C, the bottom surface of the notch 1j and the metal A tensile expansion stress is generated between the upper surface of the stage 52. In this case, as shown in FIG. 9, if the outer peripheral surface of the residual substrate portion (base semiconductor layer) 1 has a simple cut surface shape, the movement of the residual substrate portion 1 in the thickness direction is restricted. Therefore, there is a problem that the element chip 100C is lifted up in such a manner as to be jacked up by the above-described tensile force and peeled off from the metal paste layer 117 forming the adhesive layer.

  However, according to the light emitting device 100 of FIG. 1, since the hook-like portion 1g is provided in the residual substrate portion 1 (base semiconductor layer), the epoxy resin (polymer mold material) filled in the cutout portion 1j expands. The expansion stress acts in the direction in which the residual substrate portion 1 and thus the element chip 100C are pressed against the metal paste layer 117 (metal paste layer) in the bowl-shaped portion 1g. As a result, it is possible to effectively suppress problems such as the element chip 100C being lifted off from the metal paste layer 117 and peeled off. In addition, since the side surface of the main body 1m has a constricted shape as described above, the expansion stress of the mold material filled in the notch 1j can be distributed in various directions along the curved surface. 100C peeling or the like can be made more difficult to occur.

Hereinafter, a method for manufacturing the light emitting device 100 of FIG. 1 will be described.
First, as shown in Step 1 of FIG. 3, a growth substrate 10 made of an n-type GaAs single crystal is prepared, and a GaAs buffer layer (not shown) is grown on the first main surface of the growth substrate 10. Subsequently, as shown in Step 2, as the light emitting layer portion 24, an n-type AlGaInP clad layer 4, an AlGaInP active layer (non-doped) 5, and a p-type AlGaInP clad layer 6 are formed in this order in the well-known MOVPE (Metal-- Organic Vapor Phase Epitaxy) is used for epitaxial growth. Next, the process proceeds to Step 3, and a transparent thick film semiconductor layer 20 (thickness: 10 μm or more and 200 μm or less (for example, 100 μm)) made of GaP, GaAsP, or AlGaAs is formed on, for example, a hydride vapor phase growth method (HVPE). Or epitaxial growth using the MOVPE method. The transparent thick film semiconductor layer 20 may be formed by bonding a substrate made of GaP, GaAsP or AlGaAs to the light emitting layer portion 24. Thus, the formation of the main compound semiconductor layer 40 is completed.

  Then, the process proceeds to step 4 where a process of reducing the thickness of the growth substrate 10 is performed. In the present embodiment, the second main surface side portion of the growth substrate 10 is removed by grinding in this embodiment, and the remaining substrate portion is used as the substrate body 1. Thereby, an element wafer W in which the substrate main body 1 ′ is integrated with the second main surface of the main compound semiconductor layer 40 is obtained.

  Next, the process proceeds to step 5 in FIG. 4, a metal material layer for forming a bonding alloyed layer is formed on the second main surface of the substrate body 1 ′ of the element wafer W by vapor deposition or the like. The alloying heat treatment is performed in a temperature range of less than or equal to 0 ° C. to form the bonded alloyed layer 16. Further, the bonding alloying layer 9a is similarly formed on the first main surface of the transparent thick film semiconductor layer 20 (the bonding alloying layer 16 and the alloying heat treatment can be used together). As shown in FIG. 1, the bonding alloyed layer 9a is covered with the light extraction side electrode 9 by vapor deposition of Au or the like.

  Next, a support sheet 50 made of a flexible elastic material such as EVA resin is attached to the second main surface of the substrate body 1 ′ of the element wafer W, and the element wafer W is separated into individual light emitting elements as shown in Step 6. A dicing groove DG for separating into chips is formed using a known dicer so as to penetrate from the first main surface side of the wafer W to the second main surface side. At this time, the dicing blade DB may slightly bite into the support sheet 50 side as long as the support sheet 50 is not divided.

  As shown in step 7, the support sheet 50 is pulled in the plane and extended, and the dicing grooves DG between the separated element chips are expanded to form expanded grooves EG. In this state, each element chip is pressurized toward the support sheet 50, and the second main surface side of the substrate main body 1 'is press-fitted into the support sheet 50 by a certain thickness to be embedded.

  Then, the process proceeds to step 9, and the element wafer W after dicing is immersed in an etching solution (for example, a sulfuric acid / hydrogen peroxide mixture) ET having selective etching properties with respect to GaAs. The etching liquid ET penetrates into the extended groove EG and erodes from the side surface the substrate body 1 'exposed at the groove bottom side. Since the extended groove EG is widened by extending the support sheet 50 in advance, the etching solution ET easily penetrates into the groove, and the etching of the substrate body 1 'is promoted. The width of the extended groove EG should be wider than the thickness of the dicing blade DB (for example, about 30 μm), and the upper limit is particularly limited as long as the chip does not peel off due to excessive stretching of the support sheet 50. Although there is no limitation, for example, it is appropriate to set it to 50 μm or more and 200 μm or less.

  By appropriately adjusting the corrosive activity of the etchant ET, the side surface of the substrate body 1 'can be etched into a concave curved cross-sectional shape (that is, a constricted shape). On the other hand, the base end portion of the substrate body 1 ′ is protected from etching by being embedded in the embedding sheet 60. In addition, this embedding has an advantage that the individual element chips 100C ′ are less likely to drop off from the embedding sheet 60 even if etching progresses. If the etching is continued until the etching advances a certain distance in the plane in this way, and then is lifted from the etching solution and cleaned, a notch 1j having a concave curved cross-sectional shape on the side surface is formed, and the substrate main body remains. This portion becomes the main body portion 1m of the residual substrate portion 1. On the other hand, the base end portion of the substrate body portion 1 ′ embedded in the embedding sheet 60 is a hook-shaped portion 1 g.

  If the activity of the etching solution is increased, the side surface of the main body 1m can be formed into a vertical surface like the light emitting element chip 200C shown in FIG. Further, as in the light emitting element chip 300C of FIG. 7, only the base portion on the second main surface side of the residual substrate portion 1 is formed as an etching inactive layer 26 made of AlGaAs or the like which is not easily corroded by the etching solution, If the main body 1m is made of GaAs, the hook-shaped portion 1g can be formed in such a manner that the etching inactive layer 26 is left behind from the etching. In this case, the etching inert layer 26 does not necessarily need to be embedded in the embedding sheet 60. For example, the etching inactive layer 26 can be immediately transferred to the etching process in step 7 (attached to the support sheet 50) in FIG. Become. However, in consideration of prevention of falling off during the etching of the element chip 100C ′, it can be said that it is more desirable to perform the etching after the embedding in the embedding sheet 60.

  As shown in FIG. 1, in the separated light emitting element chip 100C, the second main surface side of the residual substrate portion 1 is bonded to the metal stage 52 by the metal paste layer 117, and the light extraction side electrode 9 is conductive with the bonding wire 9w. If it connects with the metal fitting 51 and the mold part 25 which consists of an epoxy resin is further formed, the light emitting element 100 will be completed.

FIG. 6 is a schematic cross-sectional view illustrating an example of a light-emitting element of the present invention. The cross-sectional schematic diagram which expands and shows the element chip | tip of FIG. Process explanatory drawing which shows an example of the manufacturing method of the light emitting element of FIG. Process explanatory drawing following FIG. Process explanatory drawing following FIG. The cross-sectional schematic diagram which shows the 1st modification of the light emitting element of FIG. The cross-sectional schematic diagram which shows the 2nd modification of the light emitting element of FIG. The figure explaining the malfunction which arises by creeping up of a metal paste.

Explanation of symbols

100 Light-Emitting Element 100C, 200C, 300C Light-Emitting Element Chip 1 Residual Substrate (Base Semiconductor Layer)
1 m Main body portion 1 j Notch portion 1 g Gutter-shaped portion 9 Light extraction side electrode 117 Metal paste layer 117 m Circulation build-up portion 24 Light emitting layer portion 40 Main compound semiconductor layer 52 Metal stage

Claims (6)

A main compound semiconductor layer having a light emitting layer portion and having a main light extraction surface formed on its first main surface side; and a light-absorbing base semiconductor layer located on the second main surface side of the main compound semiconductor layer; A second main surface of the base semiconductor layer is bonded to a metal stage via a metal paste layer, and
The at least part of the part directly below the main light extraction surface is a notch target part, and the residual part resulting from the notch includes at least part of the part directly below the light extraction side electrode. A notch is formed in the base semiconductor layer,
The base semiconductor layer is integrated with the main body forming the inner side surface of the notch and the second main surface side end of the main body, and protrudes outward from the peripheral side surface of the main body. A second main surface of the hook-shaped portion is bonded to the metal stage by the metal paste layer, and the metal paste layer is a second main surface of the hook-shaped portion. in the inner direction, circumferential portion protruding outside the side surface of the collar-shaped portion, Ri Na to form a wraparound overlaid portion around to the first main surface side of the collar-like portion through the peripheral side surface,
The height of the hook-shaped portion is 10 μm or more and 60 μm or less,
The body portion includes a light emitting element axial cross-sectional area and wherein Rukoto such form the peripheral side surface is constricted shape so that the minimum height direction intermediate portion. 2. The light emitting device according to claim 1, wherein the wraparound build-up portion covers the main body portion of the base semiconductor layer to a midway position in the height direction. The light emitting device according to claim 2, wherein a height of the main body portion is larger than a height of the wraparound build-up portion. 4. The light emitting device according to claim 1, wherein a height of the main body portion of the base semiconductor layer is set larger than a height of the bowl-shaped portion. The light emitting element according to any one of claims 1 to 4 , wherein a protruding dimension of the flange-like portion from the peripheral side surface of the main body portion is 5 µm or more. The main compound semiconductor layer is epitaxially grown on the first main surface of the light-absorbing compound semiconductor substrate, a partial region of the first main surface of the main compound semiconductor layer is used as a main light extraction surface, and the light emitting layer portion is driven to emit light The light extraction side electrode for applying a voltage is formed so as to cover a part of the first main surface of the main compound semiconductor layer;
The at least part of the portion directly below the main light extraction surface is a notch target portion, and the residual substrate portion generated as a result of the notch includes at least a portion of the portion directly below the light extraction side electrode. are cutout portions formed in the light absorbing compound semiconductor substrate, light-emitting device according to any one of claims 1 to 5 the residual substrate portion is characterized by comprising forming said base semiconductor layer .

Images