JP2005191552A - Light emitting diode and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting diode with a high luminance, which finds out a bonding layer having a high adhesive strength and an excellent thermal resistance also in a joining condition with a temperature of 500 °C or less, and reduces a stress generated at the time of joining, and can be stably manufactured, and to provide a method of manufacturing the light emitting diode. <P>SOLUTION: There are included a compound semiconductor layer containing an emission member, and an alkali glass substrate which contains any one element of 1 % or more of Na, Ca, Ba or K and is transparent to a luminescence wavelength of the emission member. The alkali glass substrate is constituted to be fixed or joined in contact with the compound semiconductor layer. The method of manufacturing the light emitting diode comprises the steps of: growing up the compound semiconductor layer on an opaque semiconductor substrate to the luminescence wavelength; joining the compound semiconductor layer and the transparent alkali glass substrate by an anode joining method; removing the semiconductor substrate; forming a primary electrode at a part of a principal plane opposite to an anode joining surface; forming a secondary ohmic electrode at other portions; and covering the primary electrode and the compound semiconductor layer having a first polarity with a metal reflective layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting diode using an alkali glass substrate pasting technique, and more particularly to a high brightness light emitting diode and a method for manufacturing the same.

2. Description of the Related Art Conventionally, a technique for removing a non-transparent semiconductor substrate and bonding a transparent substrate is known for the purpose of increasing the brightness of a light-emitting diode and improving mechanical strength. In a light emitting diode manufactured using this technique, a transparent substrate is bonded to the surface of a semiconductor layer or a surface from which an opaque semiconductor substrate is removed. As a method for bonding the transparent substrate, as disclosed in Patent Document 1, a method in which a transparent substrate is directly bonded to a semiconductor layer while applying pressure at a high temperature, or as disclosed in Patent Document 2. In addition, a method using a direct wafer bonding method and a method using a transparent adhesive material such as an epoxy resin disclosed in Patent Document 3 are known.
Further, as disclosed in Patent Document 4, a method of using a transparent conductive film such as ITO for the semiconductor layer and the transparent substrate has been proposed.

  In the prior art, it is technically difficult to join the entire semiconductor surface to a transparent substrate, and various methods have been devised. In general, the direct bonding method generally requires a high temperature and high pressure of 700 ° C. or higher, and not only a large stress is applied to the semiconductor layer, but if the surface is not smooth, the bonding becomes non-uniform and defective bonding frequently occurs. Also, joining at high temperatures is stable because of the occurrence of warpage due to differences in thermal expansion coefficient and stress due to mechanical stress, which often cracks or cracks during cooling, leading to deterioration in the quality of the light emitting part. To do so, very advanced technology and equipment are required.

On the other hand, as a method for joining a semiconductor and a transparent substrate, a method using a resin-based adhesive layer has been devised in order to cope with a semiconductor having a poor surface state. Although bonding failure due to stress at high temperature and surface roughness is improved, resin-based materials cannot withstand high temperatures, and thus there is a problem that the heat treatment process after bonding is greatly restricted. For example, in the formation of ohmic electrodes, heat treatment at 400 ° C. or higher is performed. However, the resin-based material has a problem that it changes in quality and peels off and becomes opaque.

  Also, due to the stress and the alteration of the adhesive layer, peeling and cracking of the joint frequently occur in a diode separation process such as dicing or scribing. For this reason, it has been difficult to achieve a bonding method that adheres at low temperature and low stress and satisfies heat resistance.

Japanese Patent No. 3230638 JP-A-6-302857 JP 2002-246640 A Japanese Patent No. 2588849

  In the conventional method of bonding the entire surface of a semiconductor to a transparent substrate, the quality of the light emitting part is deteriorated, and very advanced technology and equipment are required for stable production. In addition, it is difficult to achieve a bonding method that adheres at low temperature and low stress and satisfies heat resistance.

  The present invention has been proposed in view of the above problems, and has found an adhesive layer having high adhesive force and excellent heat resistance even under bonding conditions at a temperature of 500 ° C. or lower, and reducing stress generated during bonding. An object of the present invention is to provide a high-intensity light-emitting diode that can be stably produced and a method for manufacturing the same.

  In the semiconductor light-emitting diode according to the present invention, the opaque substrate is removed and the transparent substrate is affixed so that light is not absorbed by the semiconductor substrate, and an ohmic electrode and a metal reflective layer are provided on a part of the surface of the compound semiconductor layer. Thus, light from the light emitting portion can be efficiently extracted to the outside, and high brightness can be achieved. That is, the present invention provides the following means.

  The present inventor has found that an anodic bonding technique can be used for bonding a compound semiconductor layer and a transparent substrate using glass, and the compound semiconductor layer and the alkali glass substrate can be bonded stably with low stress, and have high heat resistance. I found out that I could get it.

  (1) The emission wavelength of the compound semiconductor layer including the light emitting portion and the light emitting portion including 1% by mass or more of any of the elements of sodium (Na), calcium (Ca), barium (Ba), or potassium (K). A light-emitting diode comprising: a transparent alkali glass substrate, wherein the alkali glass substrate is fixed or bonded to the compound semiconductor layer.

  (2) Concerning the sodium (Na), calcium (Ca), barium (Ba) or potassium (K) element of the alkali glass substrate, the concentration A near the semiconductor junction is lower than the concentration B on the back surface, and B> 1 A light emitting diode satisfying a relationship of 5 × A.

(3) The light-emitting diode characterized in that the alkali glass substrate has silicon dioxide (SiO ₂ ) and boron oxide (B ₂ O ₃ ) as main components and a lead content of 0.1% by mass or less.

  (4) The light emission according to any one of (1) to (3) above, wherein the joint surface between the alkali glass substrate and the compound semiconductor is mirror-finished and has a surface average roughness (rms) of 2 nm or less. diode.

(5) The light-emitting diode according to any one of (1) to (4) above, wherein the alkali glass substrate has a thermal expansion coefficient of 3 to 7 × 10 ⁻⁶ / K.

  (6) The light-emitting diode according to any one of (1) to (5) above, wherein the thickness of the alkali glass substrate is 70 μm or more and 300 μm or less, and the thickness of the compound semiconductor layer is 30 μm or less.

  (7) The light-emitting diode according to any one of (1) to (6) above, wherein the light-emitting portion included in the compound semiconductor layer includes one using AlGaInP having high emission efficiency.

  (8) The light-emitting diode according to any one of (1) to (7) above, which includes a GaP layer which is a material suitable for an etching stop layer and a current diffusion layer for etching a compound semiconductor layer.

  (9) The light-emitting diode according to any one of (1) to (8) above, wherein the semiconductor layer and the alkali glass substrate have an As content of 0.1% by mass or less.

  (10) a step of growing a compound semiconductor layer lattice-matched to a semiconductor substrate opaque to the emission wavelength, a step of bonding the compound semiconductor layer and the alkali glass substrate by an anodic bonding method, and a step of removing the opaque semiconductor substrate Forming a first ohmic electrode having a first polarity on a part of a main surface opposite to the anodic bonding surface of the compound semiconductor layer; and a second ohmic electrode having a second polarity on the compound semiconductor layer And a step of forming a metal reflective layer that covers the first ohmic electrode and the compound semiconductor layer having the first polarity.

  (11) In addition to the invention of (10) above, a compound semiconductor layer including a light emitting portion is grown on a semiconductor substrate opaque to the emission wavelength, the surface is polished, and the surface average roughness (rms) is set. The manufacturing method of the light emitting diode characterized by including the process to join, after making it 2 nm or less.

  (12) The material of the reflective layer is gold (Au) or rhodium (Rh) which has a high reflectance and is materially stable. The manufacturing method of the light emitting diode of description.

  (13) The bonding described above is performed by anodic bonding, and the temperature of the semiconductor substrate in the anodic bonding is in the range of 300 to 500 ° C. The method for producing a light-emitting diode according to any one of the above.

  (14) The step of removing the opaque semiconductor substrate includes a step of removing the compound semiconductor layer, and the step of removing the compound semiconductor layer includes a selective etching treatment step of etching only crystals having a desired composition. The method for producing a light-emitting diode according to any one of the above items (11) to (14), which is a process including the steps.

  (15) A method for producing a light-emitting diode, comprising a step of covering the light-emitting layer with a protective film and improving reliability.

  (16) A light-emitting diode lamp having a flip-chip configuration in which the electrodes of a light-emitting diode chip manufactured by the method for manufacturing a light-emitting diode according to any one of (10) to (16) above are joined by gold (Au) bumps .

  (17) The light-emitting diode lamp as described in (16) above, wherein the electrodes of the light-emitting diode chip are joined using a low melting point (450 ° C. or lower) brazing alloy to form a flip chip type.

The transparent glass substrate used for anodic bonding is so-called alkali glass mainly composed of boron oxide and silicon oxide, and includes sodium oxide, calcium oxide, barium oxide, potassium oxide, and the like. In the present invention, the concentration of sodium (Na), calcium (Ca), barium (Ba), or potassium (K) element in the alkali glass is 1 mass% or more. The upper limit of these elements is 30% by mass, preferably 15% by mass or less, and more preferably 10% or less. When these elements exceed 30% by mass, the bonding strength may be reduced or alkali contamination may be caused. Moreover, the material which does not contain lead or arsenic is desirable from the point of environmental load. The alkali glass substrate preferably has a thermal expansion coefficient in the range of 3 to 7 × 10 ⁻⁶ / K, which is close to that of the compound semiconductor layer. This is because if the difference in the thermal expansion coefficient is large, the stress on the semiconductor layer during heating and cooling cannot be reduced.

  The thickness of the alkali glass substrate is preferably 300 μm or less from the viewpoint of ease of processing into chips, and is preferably 70 μm or more from the viewpoint of generation of cracks when bonding the transparent substrate and handling of the chip assembly process such as die bonding. Further, the lead content in the alkali glass substrate is desirably 0.1% by mass or less, preferably 0.01% by mass or less, more preferably 0.01% by mass or less to 0.0001% by mass. The range up to is desirable.

  As the opaque semiconductor substrate on which the compound semiconductor layer is grown, a substrate such as GaAs, InP, GaP, or Si can be used. The light emitting part is, for example, GaP, AlGaInP mixed crystal, or GaAlAs mixed crystal, and other semiconductors used in known compound semiconductor light emitting diodes can also be used. As the light emitting part, a structure of a light emitting part that is usually used, such as a single hetero structure, a double hetero structure, or a quantum well structure, can be used. The light-emitting diode having the structure of the present invention is particularly effective in improving the luminance of a light-emitting diode having an AlGaInP light-emitting portion using a GaAs substrate that is opaque in a normal structure from the viewpoint of lattice matching because it is difficult to increase the film thickness. Is big.

  In order to obtain a light-emitting part with high brightness, it is common to select a material of the light-emitting part having a lattice constant matched to the semiconductor substrate and grow a compound semiconductor layer. As a growth method, a known technique such as a liquid phase growth method, MBE method, MOCVD method or the like can be used, but the MOCVD method is most preferable in terms of mass productivity and quality. In addition to the light emitting part, the compound semiconductor layer includes a buffer layer with a semiconductor substrate used in the prior art, a Bragg reflection layer, an etching stop layer for selective etching, a contact layer that lowers the contact resistance of the ohmic electrode, a current Known techniques such as a diffusion layer, a current blocking layer for controlling a current flow region, and a current confinement layer can be combined. These layers may be appropriately combined with necessary layers according to the manufacturing method, cost, and quality.

  When anodic bonding is performed by superimposing an alkali glass substrate and a semiconductor substrate, a commercially available anodic bonding apparatus can be used. In this method, an electric field is applied to the glass substrate and the compound semiconductor layer while heating. Furthermore, it is desirable to apply a pressure that does not shift the bonding surface during bonding. This pressure may improve the uniformity and strength of bonding. The bonding temperature is preferably a low temperature, but 300 to 500 ° C. at which good bonding can be obtained by anodic bonding is preferable, and particularly around 400 ° C. is optimal.

The opaque semiconductor substrate can be removed by methods such as machining, polishing, and chemical etching.
In particular, in chemical etching, selective etching using the difference in etching rate depending on the material is the optimum method in terms of mass productivity, reproducibility, and uniformity. The selective etching is, for example, a method of selectively etching only a GaAs layer when an AlGaInP layer is deposited on a GaAs substrate.

  On the surface of the compound semiconductor layer from which the light extraction surface is a transparent substrate and the opaque substrate is removed, a part of the first electrode and the compound semiconductor layer is removed, and the second polar compound semiconductor layer is formed on the second polar compound semiconductor layer. It is optimal to use a flip-chip type light emitting diode structure in which an electrode is formed and a metal reflective layer covering the first electrode and the surface of the compound semiconductor layer is provided.

  Other diode manufacturing methods can use known light-emitting diode manufacturing techniques, and manufacture light-emitting diodes through ohmic electrode formation, protective film formation, chip separation, and inspection / evaluation processes.

  In this example, a manufacturing example of a semiconductor light emitting diode according to the present invention will be specifically described with reference to the drawings. Obviously, the present invention is not limited to these examples.

(Example 1)
1 and 2 are views showing the manufactured semiconductor light emitting diode, FIG. 1 is a plan view thereof, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a detailed view of the layer structure of a semiconductor epiwafer used in a semiconductor light emitting diode. The manufactured semiconductor light emitting diode is a red light emitting diode (LED) having AlGaInP as a light emitting layer.

In this LED, as shown in its cross-sectional structure in FIG. 3, first, the LEDs were sequentially stacked on a semiconductor substrate 11 made of a GaAs single crystal having a surface inclined by 2 ° from an n-type (001) surface doped with Si. , Si-doped n-type GaAs buffer layer 130, Si-doped n-type (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P etching stop layer 131, Si-doped n-type (Al _0.7 Ga lower cladding layer 132 made of _{0.3) 0.5} in _0.5 P, an undoped _{(Al 0.2 Ga 0.8) 0.5 in} 0.5 emitting layer 133 consisting of P, and Zn-doped p-type _{(Al 0.7 Ga 0.8) 0.5 in} 0.5 P The compound semiconductor layer 13 is formed of the upper clad layer 134 and the Zn-doped p-type GaP layer 135. In addition, the light emitting portion 12 of this LED has a double hetero structure composed of a lower cladding layer 132, a light emitting layer 133, and an upper cladding layer 134.

In this example, first, trimethylaluminum ((CH ₃ ) ₃ Al), trimethyl gallium ((CH ₃ ) ₃ Ga), and trimethylindium ((CH ₃ ) ₃ In) were used as raw materials for group III constituent elements. The compound semiconductor layers 130 to 135 were laminated on the semiconductor substrate 11 by an organic metal chemical vapor deposition method (MOCVD method) to form an epitaxial wafer. Diethyl zinc ((C ₂ H ₅ ) ₂ Zn) was used as a Zn doping raw material.
Disilane (Si ₂ H ₆ ) was used as a Si doping material. Further, phosphine (PH ₃ ) or arsine (AsH ₃ ) was used as a raw material for the group V constituent elements. The lamination temperature in the MOCVD method of each layer constituting the compound semiconductor layer 13 was unified to 730 ° C.

The carrier concentration of the GaAs buffer layer 130 was about 5 × 10 ¹⁸ cm ⁻³ and the layer thickness was about 0.2 μm. The etching stop layer 131 has an (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P carrier concentration of about 2 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 1 μm. The lower cladding layer 132 has a carrier concentration of about 8 × 10 ¹⁷ cm ⁻³ and a layer thickness of about 1 μm. The light emitting layer 133 was undoped 0.5 μm. The carrier concentration of the upper clad layer 134 was about 2 × 10 ¹⁷ cm ⁻³ and the layer thickness was 1 μm. The carrier concentration of the GaP layer 135 was about 5 × 10 ¹⁸ cm ⁻³ and the layer thickness was 7 μm.

Next, the epitaxially grown compound semiconductor layer surface was polished, and the surface average roughness was processed to 0.5 nm. This roughness can be evaluated by observing the cross section using an optical surface roughness meter, an atomic force microscope, or an electron microscope. As the transparent substrate 150, so-called Pyrex (registered trademark) glass (thermal expansion coefficient 5 × 10 ⁻⁶ / K) having a thickness of 150 μm mainly composed of B ₂ O ₃ and SiO ₂ was used. Of course, the surface is mirror-finished with an average surface roughness of 1 nm.

  Next, the compound semiconductor layer and the transparent substrate were set to overlap with each other in the anodic bonding apparatus. The inside of the apparatus was evacuated. The semiconductor layer and the transparent substrate were sandwiched between upper and lower heaters and heated to 400 ° C. Further, a voltage of +800 V was applied to the transparent substrate surface, and both were directly bonded. The joining time at this time was 15 minutes. The total concentration of Na, Ca, K, and Ba elements on the bonded surface of the glass substrate after bonding was about 3% by mass near the bonded surface and about 6% by mass on the back surface. Therefore, the alkali concentration on the back surface was about twice that of the bonded surface.

  Next, the opaque GaAs substrate 11 and the GaAs buffer layer 130 were selectively removed with a known ammonia-based etchant. An AuGe alloy was formed as a first ohmic electrode 15 on the surface of the etching stop layer 131 by a vacuum deposition method so as to have a thickness of 0.3 μm. Patterning was performed using a general photolithography means to form a triangular linear n-type ohmic electrode 15 having a line width of about 8 μm.

  A metal reflective layer 14 made of gold (Au) and having a thickness of 1.5 μm was formed on the entire surface of the compound semiconductor layer 13 including the surface of the electrode 15 by a vacuum deposition method. Rhodium (Rh) may be used instead of gold.

  Patterning was performed, and selective etching was performed with a bromine-based etchant until the GaP layer 135, which is a current diffusion layer having a radius of 150 μm, was exposed so that the second electrode could be formed.

  In order to form the second ohmic electrode 16, a pattern is formed in a fan-shaped region having a radius of 130 μm on the surface of the GaP layer 135. First, a gold / beryllium alloy having a thickness of 0.5 μm and a thickness of 1 μm The gold to be deposited was deposited on the resist surface of the patterning by a general vacuum deposition method. Subsequently, the resist was removed by a known lift-off method to form a fan-shaped second ohmic electrode 16.

  Next, after forming the first and second electrodes, an alloying heat treatment is performed at 450 ° C. for 10 minutes in a nitrogen stream to form a low-resistance ohmic contact between the first and second electrodes and the compound semiconductor layer. did.

  As described above, the first electrode 15 and the second electrode 16 provided with the metal reflection layer 14 are formed, and the compound semiconductor layer in a region to be cut into a chip is removed by etching to expose the glass surface, The semiconductor light emitting diode 10 was obtained by cutting into individual diode shapes by a normal scribing method and subdividing them individually. As shown in FIG. 1, the semiconductor light emitting diode 10 is a square having a side of 300 μm when viewed in plan, and has a thickness of about 160 μm.

  Furthermore, a light-emitting diode lamp 20 having a flip chip structure assembled using the semiconductor light-emitting diode 10 will be described with reference to a plan view 6 and a sectional view 7. Gold ball bumps 46 are formed on the first electrode terminal 44 and the second electrode terminal 43 formed on the substrate 45, and the second electrode 16 and the metal reflective layer 14 of the light emitting diode 10 are formed on the gold bumps thereon. 46 was brought into contact with pressure contact and connected. Next, it was sealed with a transparent epoxy resin 41 to produce a light emitting diode lamp (LED) 20.

When a current is passed in the forward direction through the first electrode terminal 44 and the second electrode terminal 43 of the LED fabricated as described above, the emitted light is reflected by the metal reflection layer 14 and the transparent GaAs layer 135 is reflected. Red light having a dominant wavelength of about 620 nm was emitted through the surface and side surfaces of the film. The forward voltage (V _f : per 20 mA) when a current of 20 mA (mA) is passed in the forward direction reflects the good ohmic characteristics of the electrodes 15 and 16 and is about 2.0 volts (V). It became. The luminous intensity at this time was high brightness of 180 mcd, reflecting that the luminous efficiency of the light emitting part was high and the efficiency of taking out to the outside was devised.

  In the above description, an LED is manufactured using an n-type semiconductor substrate. However, an LED manufactured using a p-type semiconductor substrate can also achieve the effects of the present invention.

  In addition, although the above light emitting part uses an AlGaInP double heterostructure, the effect of the present invention can also be obtained by using a known light emitting part such as an MQW structure. In the above embodiment, the n-type ohmic electrode 15 has a triangular shape. However, it is desirable to form an electrode pattern as shown in FIGS. 8 to 13 so that a current flows uniformly to the light emitting portion. It is clear that the chip shape may be a triangle or a rectangle. In the electrode pattern shown in FIG. 8, an electrode for n-type region (hereinafter referred to as n-electrode) 15 is disposed so as to be equidistant from an electrode for p-type region (hereinafter referred to as p-electrode) 16, and The current flows uniformly. In the electrode pattern shown in FIG. 9, the p electrode is meshed to make the potential applied to the n electrode uniform. Further, the electrode pattern shown in FIG. 10 is such that the portion where the distance between the electrodes is close is made thin, the area and the distance are offset, and the current flows uniformly. In addition, the electrode pattern shown in FIG. 11 uses a parallel electrode to pass a uniform current. With this shape, the effect is significant with a rectangular chip. Further, the electrode pattern shown in FIG. 12 is intended to equalize the current by making the left and right or top and bottom symmetrical. The electrode pattern shown in FIG. 13 uses a stepping stone electrode as a p-electrode to achieve uniform current. The n electrode 15 and the p electrode 16 are further covered with a gold electrode, and the gold electrode is connected to an external electrode to supply current.

  In the above description, a general chip-type LED is shown. However, the same effect can be obtained with a so-called bullet-type or display package having a different shape, or a light-emitting diode having a different emission wavelength.

(Example 2)
Using the same process as in Example 1 above, bonding was performed by applying a pressure of 2 kg / cm ² (19.8 N / cm ² ) during anodic bonding. Other steps are the same as those in the first embodiment. Regarding the characteristics of the light emitting diode, the forward voltage (V _f : per 20 mA) when a current of 20 milliamperes (mA) was passed in the forward direction was about 2.0 volts (V). At this time, the emission intensity was as high as 170 mcd.

(Comparative example)
Table 1 also shows the evaluation results of comparative examples using the same process as in Examples 1 and 2 above and changing the joining conditions. In Comparative Examples 1 to 3, thermocompression bonding without using anodic bonding was performed, but the semiconductor layer and the glass substrate could not be bonded.

  In Comparative Examples 4 and 5, anodic bonding was performed under conditions where the thermal expansion coefficient of the glass was significantly different from that of the semiconductor layer. Cracks occurred during the joining process, and the diode could not be fabricated. In Comparative Example 6, the bonding was performed under the condition that the surface roughness of the semiconductor layer was rough, but peeling occurred during the substrate removal process, and the light emitting diode could not be manufactured.

  Comparative Example 7 shows a 300 μm-square semiconductor light emitting diode manufactured with a general structure using the same epi-wafer as in Example 1 without removing the opaque substrate and bonding the glass substrate, as shown in FIGS. 4 is a plan view of the semiconductor light-emitting diode manufactured in Comparative Example 7, and FIG. 5 is a cross-sectional view taken along line VV in FIG. 4 and 5, reference numeral 23 denotes a semiconductor layer, 25 denotes a first ohmic electrode, 26 denotes a second ohmic electrode formed on the back surface of the semiconductor substrate 21, and 21 denotes a GaAs substrate.

In Comparative Example 5, the upper ohmic electrode 25 is connected by gold wire bonding. In order to obtain an area necessary for this connection, the first ohmic electrode 25 was formed into a circle having a diameter of 130 μm.
Further, a p-type ohmic electrode made of gold / beryllium alloy is formed as a first ohmic electrode 25 on the surface of the semiconductor layer 23 by a vacuum deposition method so that the thickness is 0.3 μm and gold is 1 μm. did. Using a general photolithography means, patterning was performed to form a circular first ohmic electrode 25 having a diameter of 130 μm.

After that, when a current was passed in the forward direction to the first electrode terminal and the second electrode terminal of the flip chip type LED manufactured in the same manner as in the example, the wavelength was changed through the surface and side surfaces of the transparent GaP layer 135. Red light having a wavelength of about 620 nm was emitted. The forward voltage (V _f : per 20 mA) when a current of 20 mA (mA) was passed in the forward direction was about 2.0 volts (V), which was the same as in the example. The emission intensity at this time was 60 mcd. The emission intensity was less than half that of the example of the present invention. This is considered to be due to the fact that the light extraction is absorbed by the GaAs substrate and the efficiency of taking out to the outside is reduced.

  As described above, in the semiconductor light emitting diode of the present invention, the removal of the opaque substrate and the attachment of the transparent substrate eliminates light absorption in the semiconductor substrate, and further, an ohmic electrode is formed on a part of the surface of the compound semiconductor layer. By providing the metal reflective layer, the light from the light emitting portion can be efficiently extracted to the outside, and high brightness can be achieved. It is obvious that the present invention can be applied not only to light emitting diodes in the infrared and visible light regions but also to light emitting diodes in the far infrared or near ultraviolet region.

  In addition, the flip-chip structure has an effect that the lamp can be easily assembled, the wire is not broken, and the reliability is improved.

  Further, by optimizing the bonding method between the glass and the compound semiconductor layer, there is almost no cracking or peeling, and high productivity can be obtained, so that a low-cost process is possible.

It is a top view of the semiconductor light emitting diode concerning Example 1, 2 of this invention. It is a figure which shows the cross section along the II-II line | wire of FIG. 1 of the semiconductor light-emitting diode concerning Example 1, 2 of this invention. It is a figure which shows the cross section of the epiwafer concerning Example 1, 2 of this invention, and Comparative Examples 1-6. 10 is a plan view of a semiconductor light emitting diode according to Comparative Example 7. FIG. It is a figure which shows the cross section along the VV line | wire of FIG. 4 of the semiconductor light-emitting diode concerning the comparative example 7. FIG. It is a figure which shows the top view of the light emitting diode which concerns on Example 1, 2 of this invention, and Comparative Examples 1-6. It is a figure which shows sectional drawing of the light emitting diode which concerns on Example 1, 2 of this invention, and Comparative Examples 1-6. FIG. 8 is a plan view of an example in which the n-type region electrode is arranged so as to be equidistant from the p-type region electrode, which is a modification of the structure of FIG. 1. FIG. 9 is a plan view of an example in which the p-electrode is meshed and the potential applied to the n-electrode is made uniform, which is a modification of the structure of FIG. 1. FIG. 2 is a plan view of an example in which a portion having a short distance between electrodes is thinned so that an area and a distance are offset and a current flows uniformly, which is a modification of the structure of FIG. 1. It is a modification of the structure of FIG. 1 and is a diagram showing a plan view of an example in which a uniform current is made to flow using parallel electrodes. It is a figure which shows the top view of the example which aimed at equalization | homogenization of the electric current by making the right and left or the upper and lower sides symmetrical. It is a modification of the structure of FIG. 1, and is a figure which shows the top view of the example which aimed at the uniformization of an electric current by using a stepping stone electrode as a p electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light emitting diode 11 Semiconductor substrate 12 Light emission part 13 Semiconductor layer 14 Metal reflective layer (Au)
15 First electrode (ohmic)
16 Second electrode (ohmic)
DESCRIPTION OF SYMBOLS 20 Light emitting diode lamp 21 Semiconductor substrate 23 Semiconductor layer 25 1st electrode 26 2nd electrode 41 Epoxy resin 42 Light emitting diode 43 1st electrode terminal 44 2nd electrode terminal 45 Board | substrate 46 Gold bump 130 Buffer layer 131 Etching stop layer 132 Lower cladding layer 133 Light emitting layer 134 Upper cladding layer 135 GaP layer 150 Transparent substrate (glass)

Claims (17)

  Transparent to the emission wavelength of the compound semiconductor layer including the light emitting portion and the light emitting portion including 1% by mass or more of any of the elements of sodium (Na), calcium (Ca), barium (Ba), or potassium (K) A light-emitting diode comprising: an alkali glass substrate, wherein the alkali glass substrate is fixed or bonded in contact with the compound semiconductor layer.   Regarding the sodium (Na), calcium (Ca), barium (Ba) or potassium (K) element of the alkali glass substrate, the concentration A near the semiconductor junction is lower than the concentration B on the back surface, and B> 1.5 × A The light emitting diode according to claim 1, wherein: The alkali glass substrate is composed mainly of silicon dioxide (SiO ₂ ) and boron oxide (B ₂ O ₃ ), and the lead content is 0.1% by mass or less. A light emitting diode according to claim 1.   4. The light-emitting diode according to claim 1, wherein the bonding surface between the alkali glass substrate and the compound semiconductor layer has a surface average roughness (rms) of 2 nm or less. 5. The light-emitting diode according to claim 1, wherein the alkali glass substrate has a thermal expansion coefficient of 3 to 7 × 10 ⁻⁶ / K.   6. The light emitting diode according to claim 1, wherein the thickness of the alkali glass substrate is 70 μm or more and 300 μm or less, and the thickness of the compound semiconductor layer is 30 μm or less.   The light-emitting diode according to claim 1, wherein the light-emitting portion included in the compound semiconductor layer is a light-emitting portion configured using AlGaInP.   The light emitting diode according to claim 1, wherein the compound semiconductor layer includes a GaP layer.   The light-emitting diode according to any one of claims 1 to 8, wherein the compound semiconductor layer and the alkali glass substrate have an As content of 0.1 mass% or less.   A step of growing a compound semiconductor layer on a semiconductor substrate opaque to the emission wavelength, a step of bonding the grown compound semiconductor layer and an alkali glass substrate transparent to the emission wavelength by an anodic bonding method, Removing the opaque semiconductor substrate; forming a first ohmic electrode having a first polarity on a part of the main surface of the compound semiconductor layer opposite to the anodic bonding surface; and the grown semiconductor layer Forming a second ohmic electrode on the compound semiconductor layer having the second polarity, and forming the first ohmic electrode and the compound semiconductor layer having the first polarity among the grown semiconductor layers. A method for manufacturing a light-emitting diode according to claim 1, further comprising a step of covering with a reflective layer.   The surface on which the compound semiconductor layer including the light emitting part is grown on the semiconductor substrate opaque to the emission wavelength is polished, and the surface average roughness (rms) is set to 2 nm or less. The method of manufacturing a light emitting diode according to claim 10, further comprising a step of bonding to a transparent glass substrate.   The method of manufacturing a light emitting diode according to claim 10 or 11, wherein the metal reflective layer is a layer formed using gold (Au) or rhodium (Rh).   The semiconductor substrate and the glass substrate are bonded by an anodic bonding method, and the temperature of the semiconductor substrate in the anodic bonding is in a range of 300 to 500 ° C. The manufacturing method of the light emitting diode of description.   The step of removing the opaque semiconductor substrate includes a step of removing a part of the compound semiconductor layer, and the step of removing a part of the compound semiconductor layer includes a selective etching process step of etching only crystals having a desired composition. The method for manufacturing a light-emitting diode according to claim 11, wherein the method is a process.   The method for manufacturing a light emitting diode according to claim 11, further comprising a protective film forming step of forming a protective film covering the light emitting layer of the light emitting portion.   A light-emitting diode manufactured by using the light-emitting diode according to any one of claims 1 to 9 or the light-emitting diode manufacturing method according to any of claims 10 to 15 is bonded to a gold (Au) bump. A light-emitting diode lamp assembled so as to have a flip-chip structure using the LED.   The light emitting diode lamp according to claim 16, wherein the light emitting diode is assembled by a flip chip process by bonding using a brazing alloy having a low melting point (450 ° C or lower).

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