JP2012190905A - Method of manufacturing semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniform unevenness of an uneven part, and to suppress variation in light-emission output between semiconductor light-emitting elements.SOLUTION: The method includes: a step of laminating on a semiconductor substrate a plurality of paired layers 33 having a first semiconductor layer and a second semiconductor layer as one pair to form a light reflection part 30; a step of laminating on the light reflection part 30 a first clad layer, an active layer, and a second clad layer in this order to form a light-emission part 40; a step of forming a current dispersion layer on the light-emission part 40; and a step of forming an uneven part 61 on a surface of the current dispersion layer. In the method, a step of exposing a surface of the current dispersion layer to Oplasma is performed before the step of forming the uneven part 61.

Description

  The present invention relates to a method for manufacturing a semiconductor light emitting device.

In recent years, in the manufacturing process of semiconductor light emitting devices such as light emitting diodes (LEDs), a technology for growing high quality crystals such as AlGaInP and GaN based on metal-organic vapor phase epitaxy (MOVPE) method. With the development, high brightness LEDs such as blue, green, orange, yellow, and red can be manufactured.

Since the high quality crystal as described above can be grown, the internal efficiency of the semiconductor light emitting device is approaching the theoretical limit value. However, the light extraction efficiency from the semiconductor light emitting device is still low, and it is important to improve the light extraction efficiency. Therefore, a light reflecting portion is formed by laminating a plurality of pair layers, for example, two pairs of semiconductor layers having different refractive indexes as a pair, under the light emitting portion having a light emitting function by laminating a plurality of epitaxial layers. A method is adopted in which light formed and directed from the light emitting portion toward the semiconductor substrate is reflected to the light extraction surface side of the upper surface of the semiconductor light emitting element by optical interference. For example, Patent Document 1 discloses that the reflection wavelength width can be widened by continuously changing the layer thickness of a unit semiconductor layer (pair layer) of an n-type AlAs semiconductor and an n-type Al _x Ga _1-x As semiconductor. A chirped light reflecting layer is disclosed.

  In some cases, a method of forming an uneven portion on the light extraction surface on the upper surface of the semiconductor light emitting element to suppress total reflection of light on the light extraction surface and improve the light extraction efficiency.

JP 05-037017 A

  However, when the uneven portion is formed on the surface of the semiconductor layer that becomes the light extraction surface, the light extraction efficiency is improved and the light emission output of each semiconductor light emitting element is improved, but the light emission output between the semiconductor light emitting elements varies. It might happen. As a result, the yield of the semiconductor light emitting device may be reduced and the manufacturing cost may be increased.

  An object of the present invention is to provide a method for manufacturing a semiconductor light emitting device capable of making the unevenness of the uneven portion uniform, and suppressing variations in the light emission output between the semiconductor light emitting devices.

According to the first aspect of the present invention, a light reflecting portion is formed by stacking a plurality of pair layers each having a first semiconductor layer and a second semiconductor layer having different refractive indexes as one pair on a semiconductor substrate. And a first conductivity type first clad layer, an active layer, and a second conductivity type second clad different from the first conductivity type on the light reflecting portion formed on the semiconductor substrate. And laminating layers in this order to form a light emitting part, forming a current spreading layer on the light emitting part, and forming a concavo-convex part on the surface of the current dispersing layer. and, before the step of forming the uneven portion, a method of manufacturing a semiconductor light-emitting element for exposing the surface of the current spreading layer to the O ₂ plasma is provided.

According to the second aspect of the present invention, after the step of exposing to the O ₂ plasma and before the step of forming the uneven portion, the surface of the current dispersion layer exposed to the O ₂ plasma is exposed to ultraviolet rays. The manufacturing method of the semiconductor light-emitting device according to the first aspect is provided.

  According to a third aspect of the present invention, in the first or second aspect, the step of forming the concavo-convex portion is performed by an immersion method using an etching solution, and the etchant as a main component of the etching solution is acetic acid. A method for manufacturing the described semiconductor light emitting device is provided.

According to the fourth aspect of the present invention, in the step of forming the light reflecting portion, the light emitted from the active layer from the first cladding layer to the second semiconductor layer in contact with the first cladding layer. When the incident angle is θ, the first semiconductor layer having a thickness T _A obtained from the following equation (1) for each of three or more incident angles θ including at least one incident angle of 50 ° or more. When the third aspect the first to stack the formula (2) than said second semiconductor layer having a thickness determined is T _B, respectively, one or more pairs per said pair layers to each pair to each incident angle θ The manufacturing method of the semiconductor light-emitting device described in 1. is provided.
(Wherein, λ _P is the peak wavelength of light emitted from the active layer, n _in is the refractive index of the first cladding layer, and n _A is the first wavelength in the formulas (1) and (2). (The refractive index of the semiconductor layer, and n _B is the refractive index of the second semiconductor layer.)

According to a fifth aspect of the present invention, the method includes the step of forming an electrode on a part of the surface of the current spreading layer, the step of exposing to the O ₂ plasma and the unevenness after the step of forming the electrode. The method for manufacturing a semiconductor light emitting element according to the first to fourth aspects is provided.

  According to the present invention, it is possible to make the unevenness of the uneven portion uniform, and to suppress variations in light output between semiconductor light emitting elements.

It is sectional drawing which shows the manufacturing process of the semiconductor light-emitting device concerning one Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the semiconductor light-emitting device concerning one Embodiment of this invention. It is a figure which shows the manufacturing process of the semiconductor light-emitting device concerning one Embodiment of this invention, Comprising: (a) is a top view of a semiconductor light-emitting device, (b) is AA sectional drawing of (a). It is a graph which shows distribution of the light emission output of the semiconductor light-emitting element which concerns on the Example and comparative example of this invention.

<One Embodiment of the Present Invention>
Below, the manufacturing method of the semiconductor light-emitting device which concerns on one Embodiment of this invention is demonstrated.

(1) Manufacturing Method of Semiconductor Light Emitting Element A semiconductor light emitting element according to an embodiment of the present invention includes, for example, a plurality of pair layers, each having two pairs of semiconductor layers having different refractive indexes as one pair on a semiconductor substrate. A light reflecting portion formed by stacking, a light emitting portion formed by stacking a first cladding layer, an active layer, and a second cladding layer on the light reflecting portion, and formed on the light emitting portion And a current spreading layer having a concavo-convex portion formed on the surface. Each layer stacked on the semiconductor substrate is formed by, for example, the MOVPE method.

  Hereinafter, a method for manufacturing the semiconductor light emitting device according to the present embodiment will be described with reference to FIGS. 1 and 2 are cross-sectional views showing manufacturing steps of the semiconductor light emitting device 1 according to this embodiment. 3A is a plan view of the semiconductor light emitting device 1, and FIG. 3B is a cross-sectional view taken along the line AA in FIG.

(Manufacture of LED epitaxial wafers)
First, as shown in FIG. 1A, for example, an n-type GaAs layer 20 as a buffer layer is formed on an n-type GaAs substrate 10 as a semiconductor substrate having a predetermined off angle.

  Next, as shown in FIG. 1B, the light reflecting portion 30 is formed on the n-type GaAs layer 20. As shown in FIG. 1B ′, the light reflecting unit 30 includes, for example, an n-type AlAs layer 31 as a first semiconductor layer having a different refractive index and an n-type AlGaAs layer 32 as a second semiconductor layer. It is formed by laminating a plurality of pair layers 33 as one pair. Details of the light reflecting section 30 will be described later.

  Subsequently, as shown in FIG. 1C, on the light reflecting portion 30, an n-type AlGaInP cladding layer 41 as a first cladding layer of the first conductivity type, an undoped AlGaInP active layer 42 as an active layer, A p-type AlGaInP cladding layer 43 as a second cladding layer of a second conductivity type different from the first conductivity type is stacked in this order to form the light emitting section 40.

  Next, a p-type GaInP layer 50 as an intervening layer is formed on the light emitting unit 40, and a p-type GaP layer 60 as a current spreading layer is formed on the p-type GaInP layer 50.

  Thus, an LED epitaxial wafer having a predetermined emission peak wavelength is manufactured.

The formation of each layer by the MOVPE method is performed by carrying the n-type GaAs substrate 10 into the MOVPE apparatus and supplying a predetermined source gas at a predetermined flow rate while maintaining the growth pressure and growth temperature at predetermined values. As the source gas, for example, an organic metal gas such as trimethylgallium (TMGa) or triethylgallium (TEGa) is used as a gallium (Ga) source. Further, for example, an organic metal gas such as trimethylaluminum (TMAl) is used for an aluminum (Al) source and trimethylindium (TMIn) is used for an indium (In) source. Further, arsenic (As) source uses arsenic (AsH ₃ ) or the like, and phosphorus (P) source uses hydride gas such as phosphine (PH ₃ ). At this time, the ratio (quotient) in which the number of moles of the group III source gas such as TMGa and TMAl is the denominator and the number of moles of the group V source gas such as AsH ₃ and PH ₃ is the numerator, that is, the V / III ratio, Set to a predetermined value.

In addition, the addition of the conductivity determining impurity used for controlling the conductivity type of each layer is performed by adding a predetermined additive source gas (added gas) to the source gas, for example. For example, selenium (Se) is used as the n-type conductivity determining impurity. In order to add Se, an additive gas such as hydrogen selenide (H ₂ Se) is used. Further, as the p-type conductivity determining impurity, for example, magnesium (Mg) is used. In order to add Mg, for example, an additive gas such as biscyclopentadienyl magnesium (Cp ₂ Mg) is used.

(Detailed explanation of the light reflection part)
As described above, the light reflecting unit 30 includes two types of semiconductor layers having different refractive indexes, for example. As a result, when a part of the light having a predetermined wavelength generated in the undoped AlGaInP active layer 42 enters the light reflecting portion 30, the incident light is caused by causing optical interference between the two types of semiconductor layers. Reflect. That is, the plurality of pair layers 33 function as a distributed Bragg reflector (DBR) for light having a predetermined wavelength. The wavelength of light to be reflected can be selected by controlling the refractive index and thickness of each semiconductor layer.

  The refractive indexes of the n-type AlAs layer 31 and the n-type AlGaAs layer 32 constituting the light reflecting unit 30 are controlled by adjusting the composition ratios of the respective layers, for example.

The thickness _{T B} of the thickness _{T A} and n-type AlGaAs layer 32 of n-type AlAs layer 31 for reflecting light of a predetermined wavelength incident at a predetermined angle, the following formula (1) are respectively calculated by (2) be able to.

Here, in Formula (1) and Formula (2), λ _P is a peak wavelength of light emitted from the undoped AlGaInP active layer 42. Also, n _in is the refractive index of the n-type AlGaInP cladding layer 41 directly above the light reflecting portion 30. N _A is the refractive index of the n-type AlAs layer 31, and n _B is the refractive index of the n-type AlGaAs layer 32. Θ is the incident angle of the light from the n-type AlGaInP cladding layer 41 to the n-type AlGaAs layer 32 in contact with the n-type AlGaInP cladding layer 41. Here, the incident angle is an angle with respect to the normal line of the incident surface.

In the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 05-037017), a unit semiconductor layer of an n-type AlAs semiconductor and an n-type Al _x Ga _1-x As semiconductor is obtained so that a wide reflection wavelength width and a high reflectance can be obtained. The thickness change ratio, the number of stacked layers, and the mixed crystal ratio of the (pair layer) are mutually defined, and a chirped light reflection layer (light reflection portion) in which the layer thickness of the pair layer is continuously changed is obtained. However, with this structure, it is difficult to improve the light emission output of the semiconductor light emitting device without increasing the thickness and the number of layers of the light reflecting portion, and the production of the gas consumption and growth time required for epitaxial growth increases. It costs money.

  In addition, as described above, the semiconductor multilayer reflective layer included in the conventional semiconductor light emitting device as the light reflecting portion including the configuration of Patent Document 1 is designed to obtain a high reflectance with respect to light incident from the vertical direction. It was. However, for example, for light incident from an oblique direction, little consideration is given to the design, so the amount of reflection with respect to the total amount of light incident on the light reflecting portion does not increase so much, and the light emission output of the semiconductor light emitting element is reduced. It was difficult to improve significantly.

In the present embodiment, based on the above equation, including the incident angle theta (1) and (2), so it was decided to determine the thickness _{T B} of the thickness of the n-type AlAs layer 31 _{T A} and n-type AlGaAs layer 32 By stacking a plurality of pair layers 33 corresponding to a plurality of incident angles θ, the amount of reflection with respect to the total amount of light incident on the light reflecting portion can be increased, and the light emission output of the semiconductor light emitting element can be greatly improved. . Further, the configuration of the corresponding pair layer 33 can be optimized by taking a fine or large value of the incident angle θ, or by appropriately selecting which value is included in the incident angle θ. . Therefore, the thickness and the number of layers of the pair layer 33 can be made close to the necessary minimum by adjusting the value and the number of incident angles θ.

In view of the above, in the semiconductor light emitting device 1 according to the present embodiment, for each of the three or more angles of incidence theta, of n-type AlAs layer 31 having a thickness of _{T A} and n-type AlGaAs layer 32 a thickness _{T B} The light reflecting portion 30 is obtained by laminating one or more pair layers 33 each having an n-type AlAs layer 31 and an n-type AlGaAs layer 32 each having a thickness T _A and T _B for each incident angle θ. Is preferably formed. At this time, it is preferable that at least one incident angle of 50 ° or more is included in the three or more incident angles θ.

(Formation of electrodes)
After the LED epitaxial wafer having each layer formed as described above is carried out of the MOVPE apparatus, electrodes are formed on the upper and lower surfaces (front and back surfaces) of the LED epitaxial wafer as shown in FIG. That is, for example, a pattern such as a photoresist is formed on the p-type GaP layer 60 by a photolithography process using a mask aligner or the like. Subsequently, for example, gold / beryllium (AuBe) alloy, nickel (Ni), and gold (Au) are vapor-deposited in this order at a thickness of 400 nm, 10 nm, and 1000 nm, respectively, by a vacuum evaporation method. After vapor deposition, a pattern such as a photoresist is removed by a lift-off method to form, for example, a substantially circular surface electrode 71 having a wire bonding portion of 100 μm in diameter for each element. Therefore, on the wafer, each surface electrode 71 is arranged on the p-type GaP layer 60 in, for example, a matrix. In FIG. 2A and the subsequent drawings, one of the plurality of surface electrodes 71 arranged in a matrix is shown.

Next, for example, a gold / germanium (AuGe) alloy, Ni, or Au is applied to the back surface of the LED epitaxial wafer, that is, the entire surface opposite to the epitaxial layer forming surface of the n-type GaAs substrate 10 by vacuum deposition. In this order, the back electrode 72 is formed by vapor deposition with a thickness of 60 nm, 10 nm, and 500 nm, respectively. Thereafter, in the alloy process, the LED epitaxial wafer on which the electrodes 71 and 72 are formed is heated to 400 ° C. for 5 minutes in, for example, a nitrogen (N ₂ ) gas atmosphere to alloy the electrodes 71 and 72.

(O ₂ plasma treatment)
Next, prior to the formation of the concavo-convex portion 61 (see FIG. 3B) on the surface of the p-type GaP layer 60 that becomes the light extraction surface of the semiconductor light emitting device 1, the surface of the p-type GaP layer 60 is subjected to O ₂ plasma. Expose to.

Conventionally, for example, by forming an uneven portion on the light extraction surface of the semiconductor light emitting element by an immersion method or the like,
Although the light extraction efficiency is improved, the light emission output may vary among the semiconductor light emitting elements. According to the inventors, it has been found that this is caused by unevenness of the uneven part.

  In order to reduce such unevenness of the uneven portion, for example, a method of forming the uneven portion by immersion treatment after forming a pattern corresponding to the uneven portion with a photoresist or the like can be considered. However, in the method using such a mask pattern, the number of steps increases and the manufacturing cost also increases. Until now, it has been difficult to control the uneven shape of the uneven portion without using a mask pattern by a simple method such as an immersion method, and to reduce the variation in the light emission output between the semiconductor light emitting elements 1.

  Therefore, the present inventors have conducted intensive research on a method for making the unevenness (roughness) of the uneven portion uniform and suppressing variations in light emission output. As a result, it has been found that the uneven shape of the uneven portion can be stably formed and the unevenness of the uneven portion can be reduced by the following method without causing an increase in manufacturing cost.

In the method for manufacturing the semiconductor light emitting device 1 according to the present embodiment, before forming the concavo-convex portion 61 shown in FIGS. 3A and 3B on the surface of the p-type GaP layer 60, as shown in FIG. Thus, the surface of the p-type GaP layer 60 is exposed to oxygen (O ₂ ) plasma.

The treatment of the surface of the p-type GaP layer 60 with O ₂ plasma is performed by batch processing using, for example, a barrel ashing apparatus. At this time, the flow rate of O ₂ gas is set to 50 sccm or more and 500 sccm or less, and the opening of the pressure adjusting valve provided in the apparatus is adjusted to set the processing pressure to 50 Pa or more and 120 Pa or less, for example. The applied power is, for example, 200 W to 800 W, and the treatment time is, for example, 1 minute to 10 minutes, preferably 3 minutes to 5 minutes. During the above process, the wafer temperature may be heated to 100 ° C. or higher and 250 ° C. or lower using a lamp heater or the like. The wafer temperature at the time of lamp heating is controlled to the predetermined value based on the result measured in advance using, for example, a thermo label.

(Formation of irregularities)
Subsequently, an uneven portion 61 (see FIG. 3B) is formed on the surface of the p-type GaP layer 60 treated with O ₂ plasma.

Formation of the concavo-convex portion 61 on the surface of the p-type GaP layer 60 is performed by, for example, an immersion method using an acetic acid (CH ₃ COOH) -based etching solution. In this case, the etchant as the main component of the etching solution is, for example, acetic acid (CH ₃ COOH). The processing time is, for example, 15 seconds or more and 90 seconds or less. By the immersion treatment using the etching solution, the exposed surface of the p-type GaP layer 60 where the surface electrode 71 is not formed is roughened, and the uneven portion 61 is formed.

  Next, the wafer having the concavo-convex portion 61 formed thereon is diced into, for example, a 275 μm square chip so that each of the plurality of surface electrodes 71 is located at the center, and FIGS. A plurality of semiconductor light emitting devices 1 shown in b) are obtained. Thus, the semiconductor light emitting device 1 according to this embodiment is manufactured.

(Semiconductor light emitting device mounting)
Thereafter, the semiconductor light emitting device 1 is mounted. That is, a plurality of individual semiconductor light emitting devices 1 cut out by dicing are mounted on, for example, a TO-18 stem, die bonded, and then wire bonded.

(2) Effects According to One Embodiment of the Present Invention According to the present embodiment, one or a plurality of effects shown below can be obtained.

(A) According to the present embodiment, the step of exposing the surface of the p-type GaP layer 60 to O ₂ plasma is performed before the step of forming the uneven portion 61. As a result, the unevenness of the uneven portion 61 can be made uniform, and variations in the light emission output between the semiconductor light emitting elements 1 can be suppressed. Therefore, the yield of the semiconductor light emitting device 1 can be improved and the manufacturing cost can be reduced.

(B) Further, according to the present embodiment, the uneven portion 61 is formed on the surface of the p-type GaP layer 60 by an immersion method using an acetic acid-based etching solution to form the uneven portion 61 with little variation. Therefore, even if it is a simple method by an immersion method, the uneven | corrugated | grooved part 61 can be formed suppressing a dispersion | variation without using a mask pattern etc., and the number of processes and manufacturing cost can be reduced.

(C) Further, according to this embodiment, for each 50 ° or angle of incidence of the three or more angles of incidence θ which contains at least one, of the thickness T _A obtained respectively from the above equation (1) an n-type AlAs layer 31, an n-type AlGaAs layer 32 having a thickness of _{T B} obtained respectively from the above equation (2), stacked one pair or more per to θ each incident angle pair layer 33, each pair. Thereby, a plurality of pair layers 33 respectively corresponding to a plurality of incident angles θ can be stacked, the amount of reflection with respect to the total amount of light incident on the light reflecting portion is increased, and the light emission output of the semiconductor light emitting element is greatly improved. be able to.

(D) Further, according to the present embodiment, the configuration of the predetermined pair layer 33 is selected by substituting an arbitrary incident angle θ into the above formulas (1) and (2). Thereby, the value and the number of incident angles θ to be adopted can be adjusted, and the thickness and the number of layers of the pair layer 33 can be brought close to the necessary minimum. Therefore, the thickness of the light reflecting portion 30 can be reduced.

(E) Further, according to the present embodiment, the treatment with O ₂ plasma and batch processing. As a result, a large number of wafers can be processed at once in a short time, and an increase in manufacturing cost can be suppressed.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, It can change variously in the range which does not deviate from the summary.

For example, in the above-described embodiment, the surface of the p-type GaP layer 60 is etched to form the uneven portion 61 after the O ₂ plasma treatment, but after the step of exposing to the O ₂ plasma. Before the step of forming the concavo-convex portion, the surface of the p-type GaP layer 60 exposed to O ₂ plasma is further irradiated with ultraviolet rays, and the organic matter on the wafer surface is decomposed and removed by the modification of the ultraviolet rays. You may perform a process.

  Moreover, in the above-mentioned embodiment, although the uneven | corrugated | grooved part 61 of the surface of the p-type GaP layer 60 was formed by the immersion method, the formation method of an uneven | corrugated | grooved part is not restricted to this. For example, the concavo-convex portion may be formed by roughening the surface by sandblasting or plasma treatment.

  Moreover, in the above-mentioned embodiment, although the uneven part 61 was formed without using a mask pattern etc., after forming a pattern with a photoresist etc., you may form an uneven part. With the above method using a mask pattern or the like, the shape can be controlled with relatively high accuracy. By applying the present invention to such a method, the controllability of the concavo-convex shape of the concavo-convex portion can be further increased, and the variation in the light emission output between the semiconductor light emitting elements can be reduced.

Moreover, in the above-mentioned embodiment, the light extraction surface which forms the uneven | corrugated | grooved part 61 is p-type GaP.
Although the surface of the layer 60 is used, the current spreading layer that becomes the light extraction surface may be a layer made of a material other than GaP. Specifically, materials such as GaAs, AlGaAs, GaAsP, and AlGaInP can also be used. Also, the light extraction surface side may be n-type by reversing the conductivity types (n-type and p-type) of the upper and lower cladding layers and the current spreading layer.

In the above-described embodiment, H ₂ Se is used as the n-type additive gas in forming each layer by the MOVPE method. However, as the n-type additive source gas (n-type additive gas), disilane ( Si ₂ H ₆ ), monosilane (SiH ₄ ), diethyl tellurium (DETe), dimethyl tellurium (DMTe), or the like can also be used. Although Cp ₂ Mg is used as the p-type additive gas, dimethyl zinc (DMZn), diethyl zinc (DEZn), or the like can also be used as the p-type additive source gas (p-type additive gas). .

  In the above-described embodiment, the substantially circular surface electrode 71 is formed. However, the surface electrode can have various shapes such as a square, a rhombus, and a polygon.

  Next, examples according to the present invention will be described together with comparative examples.

(Production of LED epitaxial wafers)
First, an LED epitaxial wafer having the same configuration as the LED epitaxial wafer according to the above-described embodiment was manufactured by the same method as that of the above-described embodiment. Specifically, an epitaxial wafer for LED was manufactured by laminating each layer by an MOVPE method on an n-type GaAs substrate having an off angle of 15 °. The composition ratio, layer thickness, growth conditions, etc. of each layer at the time of forming each layer are shown below.

Further, in Table 1, a plurality of pair layers each having an n-type AlAs layer and an n-type Al _0.5 Ga _0.5 As layer as a pair are formed in accordance with a plurality of incident angles θ. More specifically, provided on the n-type GaAs layer as a buffer layer, a 70 ° incidence angle theta, the above equation (1) and the semiconductor layer having a thickness of T _A and T _B obtained by (2) Two pairs (two layers) of pair layers (referred to as 70 ° DBR layers) were formed, and thereafter, the pair layers corresponding to the incident angle θ gradually decreasing were sequentially laminated. The detailed configuration is shown in Table 2 below. Each pair layer was laminated from the bottom to the top of Table 2. That is, in the table, the lowermost 70 ° DBR layer is a pair layer formed immediately above the n-type GaAs layer, and the uppermost 0 ° DBR layer is n-type (Al _0.7 Ga _0.3 ) _0.5. It is a pair layer in contact with the In _0.5 P clad layer.

The undoped (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P active layer included in the epitaxial wafer for LED manufactured as described above has an emission peak wavelength near 631 nm. Therefore, in the above formulas (1) and (2), λ _P is set to 631 nm. The n-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P clad layer has a refractive index n _in of 3.127, and the n-type AlAs layer has a refractive index n _A of 3.114. The refractive index n _B of the n-type Al _0.5 Ga _0.5 As layer is 3.057.

  Thus, an epitaxial wafer for red LED having an emission peak wavelength near 631 nm was obtained.

(Formation of electrodes)
Next, a front electrode and a back electrode were formed by the same method as in the above embodiment.

(O ₂ plasma treatment / formation of uneven parts)
Subsequently, the wafer on which the front electrode and the back electrode were formed was cleaved and divided into two, and an uneven portion was formed on each of the ½ wafers. At this time, an uneven portion was formed on one wafer after being subjected to O ₂ plasma treatment, and an uneven portion was formed on the other wafer without being subjected to O ₂ plasma treatment. The conditions for the O ₂ plasma treatment were an O ₂ gas flow rate of 300 sccm and a treatment pressure of 80 Pa. The applied power was 400 W and the processing time was 5 minutes. The treatment time with the acetic acid-based etching solution was 30 seconds.

Subsequently, in the same manner as in the above-described embodiment, each of the above wafers is diced and subjected to the O ₂ plasma treatment, and the semiconductor light emitting device according to the comparative example without the O ₂ plasma treatment. A plurality of semiconductor light emitting devices were manufactured. Each of the semiconductor light emitting devices of the example and the comparative example is configured as a red LED having an emission peak wavelength near 631 nm.

(Semiconductor light emitting device mounting)
Thereafter, each of the semiconductor light emitting elements was mounted by the same method as in the above embodiment.

(Measurement of semiconductor light emitting devices)
With respect to the semiconductor light emitting devices according to Examples and Comparative Examples manufactured as described above, initial characteristics such as light emission output, light emission wavelength, and forward voltage were measured. The evaluation current during measurement was 20 mA.

  FIG. 4 shows the light emission output distribution of the semiconductor light emitting devices according to the example and the comparative example. The horizontal axis in FIG. 4 is the light emission output (mW), and the vertical axis is the number of elements (number) indicating each light emission output value among the measured semiconductor light emitting elements. Moreover, in the figure, the measured value of the semiconductor light emitting element according to the example is indicated by a solid line, and the measured value of the semiconductor light emitting element according to the comparative example is indicated by a one-dot chain line.

  The average light emission output obtained from the above measured values of the individual semiconductor light emitting elements was 2.72 mW in the example and 2.71 mW in the comparative example, and there was no difference between the example and the comparative example. However, the variation in the light emission output in the example is ± 0.25 mW, which is about half that in the comparative example, as can be seen from FIG. In addition, regarding the emission wavelength and the forward voltage, there was no difference between the example and the comparative example.

As described above, it was found that the variation in the light emission output is significantly improved by performing the O ₂ plasma treatment when forming the uneven portion.

1 Semiconductor light emitting device 10 n-type GaAs substrate (semiconductor substrate)
30 Light reflecting portion 31 n-type AlAs layer (first semiconductor layer)
32 n-type AlGaAs layer (second semiconductor layer)
33 Pair layer 40 Light emitting part 41 n-type AlGaInP clad layer (first clad layer)
42 Undoped AlGaInP active layer (active layer)
43 p-type AlGaInP cladding layer (second cladding layer)
60 p-type GaP layer (current dispersion layer)
61 Concavity and convexity

Claims (5)

On the semiconductor substrate, a step of forming a light reflecting portion by laminating a plurality of pair layers each having a first semiconductor layer and a second semiconductor layer having different refractive indexes as one pair;
On the light reflecting portion formed on the semiconductor substrate, a first conductivity type first cladding layer, an active layer, and a second conductivity type second cladding layer different from the first conductivity type are provided. A step of laminating in this order to form a light emitting part;
Forming a current spreading layer on the light emitting part;
And forming a concavo-convex portion on the surface of the current spreading layer,
A method of manufacturing a semiconductor light emitting element, comprising performing a step of exposing the surface of the current dispersion layer to O ₂ plasma before the step of forming the uneven portion. A step of irradiating the surface of the current dispersion layer exposed to the O ₂ plasma with an ultraviolet ray is performed after the step of exposing to the O ₂ plasma and before the step of forming the uneven portion. The manufacturing method of the semiconductor light-emitting device according to claim 1. The step of forming the uneven portion is performed by an immersion method using an etching solution,
3. The method of manufacturing a semiconductor light emitting device according to claim 1, wherein the etchant as a main component of the etching solution is acetic acid. In the step of forming the light reflecting portion,
When the incident angle of light emitted from the active layer from the first cladding layer to the second semiconductor layer in contact with the first cladding layer is θ, at least one incident angle of 50 ° or more is included 3 For each of the two or more incident angles θ
Said first semiconductor layer of a thickness T _A obtained respectively the following formula (1), wherein the pair layer and the second semiconductor layer having a thickness of T _B obtained respectively the following equation (2), a and each pair 4. The method of manufacturing a semiconductor light emitting element according to claim 1, wherein at least one pair is stacked for each incident angle θ. 5.
(Wherein, λ _P is the peak wavelength of light emitted from the active layer, n _in is the refractive index of the first cladding layer, and n _A is the first wavelength in the formulas (1) and (2). (The refractive index of the semiconductor layer, and n _B is the refractive index of the second semiconductor layer.) Forming an electrode on a part of the surface of the current spreading layer;
5. The method for manufacturing a semiconductor light emitting element according to claim 1, wherein after the step of forming the electrode, a step of exposing to the O ₂ plasma and a step of forming the concavo-convex portion are performed.