JP3643225B2 - Optical semiconductor chip - Google Patents

Description

[0001]
【Technical field】
The present invention, LED relates to an optical semiconductor chip, such as (light emitting diode) chip and LD (laser diode) chip.
[0002]
[Prior art]
FIG. 14 shows a general structure of a conventional LED chip. This conventional LED chip has a semiconductor laminated portion 90 formed on one surface of a substrate 9, and this semiconductor laminated portion 90 is composed of an n-type semiconductor layer 90a, a light emitting layer 90b, and a p-type semiconductor layer 90c. Yes. These layers are obtained by crystal growth of a IIIb-Vb group compound semiconductor containing gallium. Since the crystal growth needs to be performed efficiently and appropriately, a semiconductor substrate such as gallium arsenide is used as the substrate 9. It is used. In order to manufacture the LED chip, a compound semiconductor is crystal-grown over a wide range of the surface of the wafer to be the semiconductor substrate, and then the wafer is cut and divided into a plurality of chip pieces.
[0003]
[Problems to be solved by the invention]
However, the conventional LED chip has the following problems.
[0004]
That is, in recent years, the usage of LED chips is still expanding, and depending on the usage, there is a strong demand for thinner LED chips. For example, when an LED chip is incorporated in an IC card that is formed in a thin card shape as a whole, it is desirable to make the thickness of the entire LED chip as small as possible. In such a case, there is a case where the thickness of the entire LED chip is strongly required to be, for example, 200 μm or less.
[0005]
However, in the conventional LED chip, the thickness t1 of the semiconductor laminated portion 90 is an extremely thin dimension of, for example, about 10 μm, whereas the thickness t2 of the substrate 9 is a dimension that is significantly larger than that of the semiconductor laminated portion 90. It was. That is, since the substrate 9 is originally formed as a wafer, the thickness t2 is 200 μm to 300 μm or more even when a considerably thin wafer is used as the wafer. It was. For this reason, conventionally, it has been practically difficult to reduce the total thickness t3 of the LED chip to, for example, about 200 μm or less, and the thickness cannot be sufficiently reduced. As a result, conventionally, for example, it may be difficult to properly incorporate the LED chip into a thin IC card in a proper manner.
[0006]
Further, such a problem occurs not only in the LED chip but also in other optical semiconductor chips such as an LD chip.
[0007]
The present invention has been conceived under such circumstances, and it is an object of the present invention to make the optical semiconductor chip thinner without deteriorating the original function of the optical semiconductor chip. It is said.
[0008]
DISCLOSURE OF THE INVENTION
In order to solve the above problems, the present invention takes the following technical means.
[0009]
According to the present onset bright, an optical semiconductor chip is provided. This optical semiconductor chip is an optical semiconductor chip provided with a semiconductor laminated portion made of a compound semiconductor crystal, and the semiconductor laminated portion is bonded to an alternative support material different from the substrate used for the crystal growth. And the said board | substrate is removed from the said semiconductor laminated part, the said semiconductor laminated part is comprised as a light emitting diode, and the whole is formed as an LED chip, and the said alternative support material is a film which has translucency. It is characterized by.
[0012]
The optical semiconductor chip provided by the present invention has a structure in which the substrate used for crystal growth of the compound semiconductor is removed from the semiconductor stacked portion. In contrast, the thickness of the entire optical semiconductor chip does not increase due to the thickness of the crystal growth substrate formed from the wafer. On the other hand, instead of the substrate, an alternative support material is bonded to the semiconductor stacked portion. However, unlike the crystal growth substrate, the alternative support material does not need to be formed from a wafer or the like. The film can be made considerably thinner than the above-mentioned substrate, for example, by using the above film. Therefore, in the present invention, an effect that the thickness of the entire optical semiconductor chip can be made considerably smaller than the conventional one can be obtained. According to the present invention, the total thickness of the optical semiconductor chip can be easily reduced to, for example, 200 μm or less. Can be optimal.
[0013]
In the present invention, since the alternative support material is adhered to the semiconductor laminated portion, the presence of the alternative support material can reinforce the semiconductor laminated portion and further increase the strength of the entire chip. Therefore, when the optical semiconductor chip according to the present invention is handled, it can be handled in the same manner as a conventional optical semiconductor chip, which is convenient. Further, since the semiconductor laminated portion may have the same structure as the semiconductor laminated portion of the conventional optical semiconductor chip, there is no problem that the optical characteristics as the optical semiconductor chip are impaired. Furthermore, in the present invention, light emitted from the semiconductor laminated portion can be transmitted to the outside through the alternative support material, and light can be emitted from both sides of the optical semiconductor chip. That is, one optical semiconductor chip can emit light in two directions. Therefore, the usage of the optical semiconductor chip can be further expanded.
[0014]
In preferable embodiment of this invention, the said alternative support material can be set as the structure which has flexibility.
[0015]
According to such a configuration, when the mounting target surface of the optical semiconductor chip is, for example, a curved surface, the alternative support material is bent along the mounting target surface, and the entire optical semiconductor chip is then mounted. It becomes possible to mount the surface appropriately on the surface. Therefore, it is advantageous in expanding the practical range of the optical semiconductor chip.
[0016]
In another preferred embodiment of the present invention, the alternative support material may be configured to have conductivity.
[0017]
According to such a configuration, the alternative support material can be used as an electrode of the optical semiconductor chip, and convenience can be achieved when electrical connection is made to the optical semiconductor chip. In addition, normally two electrodes are provided on the optical semiconductor chip, but it is not necessary to provide one of the electrodes, and the manufacturing work of the optical semiconductor chip can be simplified.
[0020]
In another preferred embodiment of the present invention, the surface opposite to the surface to which the alternative support material of the semiconductor laminated portion is bonded can be a rough surface having an uneven shape.
[0021]
According to such a configuration, the light emitted from the semiconductor stacked portion is scattered when passing through the rough surface having the uneven shape. Therefore, the brightness of the optical semiconductor chip can be increased by this light scattering effect.
[0022]
In another preferred embodiment of the present invention, a translucent electrode is provided on the entire surface or a part of the surface opposite to the surface to which the alternative support material of the semiconductor laminated portion is bonded. It can be set as a structure.
[0023]
According to such a configuration, the electrode can be electrically connected to the optical semiconductor chip using the electrode, and since the electrode has translucency, the electrode is formed. Light can be appropriately emitted from the surface of the semiconductor stacked portion toward the outside.
[0024]
In another preferred embodiment of the present invention, the electrode may be a gold thin film layer. According to such a configuration, it is possible to more appropriately connect the electric wiring to the electrode due to the gold characteristic that the conductivity is high and the surface is hardly oxidized. Gold is inherently opaque, but it can be made transparent by making its thickness sufficiently small.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be specifically described with reference to the drawings.
[0031]
FIG. 1 is a cross-sectional view showing an example of an LED chip as a specific example of an optical semiconductor chip according to the present invention.
[0032]
The LED chip A shown in the figure has a structure in which a light reflecting layer 2, a semiconductor laminated portion 3, and an electrode 4 are sequentially laminated on one surface of an alternative support material 1, and the semiconductor laminated portion 3 is configured as a light emitting diode. This LED chip A has a structure in which a substrate, which will be described later, used for crystal growth of the compound semiconductor constituting the semiconductor multilayer portion 3 is removed from the semiconductor multilayer portion 3.
[0033]
The alternative support material 1 is a thin conductive film having a thickness ta of, for example, about 10 μm to 100 μm. The conductive support material 1 is kneaded with conductive particles such as metal particles in a synthetic resin film, for example, to make the film conductive. It is a thing. This alternative support material 1 has flexibility.
[0034]
The light reflecting layer 2 is a thin film layer of Ag, Cr, Ti, or other glossy metal, and is a portion formed by depositing a predetermined metal by vapor deposition or sputtering, as will be described later. . The light reflectance of the surface of the light reflection layer 2 is also high as that of the surface of the alternative support material 1.
[0035]
The semiconductor laminated portion 3 has the same configuration as a conventionally known light emitting diode. The semiconductor stacked portion 3 uses a simple crystal of a IIIb-Vb group compound semiconductor containing gallium. For example, a GaP layer 3d as a diffusion layer, a p-type InGaAlP layer 3c, a light-emitting layer 3b, and an n-type InGaAlP The layer 3a is laminated. The light emitting layer 3b is an InGaAlP layer. Further, the entire surface or substantially the entire surface 30 of the n-type InGaAlP layer 3a, which is the outermost layer of the semiconductor laminated portion 3, is a rough surface having minute irregularities. The uneven height difference of the surface 30 is, for example, within 1 μm.
[0036]
The electrode 4 is, for example, a thin film layer of gold (Au), and is a portion where gold is deposited on the entire surface of the n-type InGaAlP layer 3a by vapor deposition or sputtering. The gold electrode 4 has a thickness of about 100 mm, for example, and has translucency.
[0037]
The LED chip A is formed, for example, as a 0.3 mm square chip piece. The total thickness tb of the light reflecting layer 2, the semiconductor laminated portion 3, and the electrode 4 is about 5 to 10 μm, and the total thickness t including the alternative support material 1 is extremely thin of about 110 μm or less. It is the dimension of.
[0038]
Next, a method for manufacturing the LED chip A will be described with reference to FIGS.
[0039]
First, as shown in FIG. 2, a plurality of semiconductor layers 3 a to 3 d are crystal-grown on the surface of a GaAs substrate 5 to produce a semiconductor stacked portion 3 that becomes a light emitting diode. This crystal growth may be performed, for example, by metal organic chemical vapor deposition (MOCVD), and a single crystal of a predetermined compound semiconductor constituting the light emitting diode can be efficiently grown by this growth method. The GaAs substrate 5 is formed as a wafer and has a thickness of 200 μm to 300 μm or more. The semiconductor laminated portion 3 is formed on the entire surface of the wafer.
[0040]
Next, as shown in FIG. 3, a predetermined glossy metal such as Ag or Cr is formed on the surface of the uppermost GaP layer 3d of the semiconductor stacked portion 3 by vapor deposition or sputtering, and the light reflecting layer 2 is formed. Make it. After that, as shown in FIG. 4, the alternative support material 1 ′ is bonded to the entire surface of the light reflecting layer 2. This alternative support material 1 'is a film formed in the same size as the wafer or larger. This alternative support material 1 ′ is a portion that becomes the above-described alternative support material 1, has conductivity and flexibility, and has a thickness of about 10 μm to 100 μm. As a means for adhering the alternative support material 1 ′ to the light reflecting layer 2, an adhesive may be used, or the alternative support material 1 ′ is softened by heating and is subjected to thermocompression bonding. Such means may be employed, and any of them may be used in the present invention.
[0041]
After the bonding operation of the alternative support material 1 ′, the GaAs substrate 5 used for crystal growth is removed from one surface of the semiconductor stacked portion 3 as shown in FIG. This operation can be performed by, for example, an etching process in which the GaAs substrate 5 is immersed in an etching process liquid in which ammonia and hydrogen peroxide are mixed. Further, instead of such an etching process, for example, the GaAs substrate 5 may be ground and removed by mechanical means. However, from the viewpoint of workability and protection of the semiconductor laminated portion 3, it is preferable to perform the etching process.
[0042]
After the GaAs substrate 5 is removed, as shown in FIG. 6, the surface 30 of the n-type InGaAlP layer 3 a located at the outermost layer of the semiconductor stacked portion 3 is made to have a rough surface. This operation can be performed by an etching process in which the n-type InGaAlP layer 3a is immersed in a hydrochloric acid-based etching solution. After that, as shown in FIG. 7, the gold electrode 4 is formed on the surface 30 of the n-type InGaAlP layer 3a. This operation can be performed by depositing gold or sputtering.
[0043]
According to the above-described series of work steps, each of the light reflection layer 2, the semiconductor stacked portion 3, and the electrode 4 is formed in a series with substantially the same area as the original GaAs substrate 5 on one surface of the alternative support material 1 ′. The intermediate product A ′ thus obtained is obtained. Then, as shown in FIG. 8, if the intermediate product A ′ is cut so as to be divided into a plurality of chip pieces, a large number of LED chips A shown in FIG. 1 can be obtained. The intermediate product may be cut using, for example, a diamond cutter or a laser cutter, as in a general wafer dicing process. In the LED chip A thus manufactured, the order of the semiconductor layers 3a to 3d of the semiconductor laminated portion 3 with respect to the alternative support material 1 is opposite to the order of lamination with respect to the GaAs substrate 5 shown in FIG.
[0044]
The LED chip A having the above configuration has a total thickness t of 110 μm or less, so to speak, it is configured as a thin-film LED chip. Therefore, the LED chip A can be incorporated with a relatively large margin even inside a thin IC card having a total thickness of about 0.7 mm, for example, and a large mounting space can be secured. It is very convenient to use it in a difficult space.
[0045]
Further, since the alternative support material 1 of the LED chip A has flexibility, even if the mounting surface of the LED chip A is a curved surface that is slightly curved, for example, the alternative support material 1 is made to be a curved surface. It can be bent along, and surface mounting can be ensured. Furthermore, since the LED chip A has a structure in which the alternative support material 1 is bonded to one surface of the semiconductor multilayer portion 3, the semiconductor multilayer portion 3 is reinforced by the alternative support material 1. Therefore, when the LED chip A is handled, it is possible to eliminate that each part of the LED chip A is easily damaged.
[0046]
FIG. 9 is a cross-sectional view of an essential part showing an example of the mounting structure of the LED chip A.
[0047]
In the mounting structure shown in the figure, the LED chip A is bonded onto the terminal part 60 made of copper foil or the like formed on the surface of the circuit board 6, and the alternative support material 1 is electrically connected to the terminal part 60. . Further, one end portion of a metal spring plate-like terminal plate 62 is supported on the standing portion 61 provided on the upper surface of the circuit board 6, and the other end portion of the terminal plate 62 is connected to the LED chip A. The electrode 4 is in contact with the surface of the electrode 4, and the contact state is maintained by the elastic force of the terminal plate 62. The LED chip A and the terminal board 62 are covered with a transparent sealing resin 63 such as an epoxy resin. As a means for bonding the LED chip A to the terminal portion 60, a means using a conductive adhesive or a thermocompression bonding means that pressurizes the alternative support material 1 while heating can be used.
[0048]
In the above structure, since the alternative support material 1 of the LED chip A is used as an electrode as it is, the production of one of the two electrodes necessary for the LED chip A can be omitted. In addition, since the terminal chip 62 is brought into contact with the LED chip A using its elasticity, the following advantages can be obtained as compared with the case where wire bonding is performed on the LED chip A. . That is, when wire bonding is performed on the electrode 4 of the LED chip A, the capillary of the wire bonder presses the upper surface of the LED chip A with a considerably large pressure. On the other hand, in the above structure, since the terminal plate 62 is merely brought into contact with the electrode 4, the LED chip A can be prevented from receiving a large pressure, and mechanical damage is caused to the LED chip A. This is advantageous in that it does not occur. In particular, since the electrode 4 is made of gold with good electrical connectivity, electrical connection with good electrical conductivity can be performed without increasing the contact pressure with the terminal plate 62 so much. Further, in the case of wire bonding, a part of the wire extends upward from the joint portion with the LED chip A by a certain dimension, and the wire is bulky above the circuit board 6. By setting the terminal board 62 to be substantially horizontal, the height of the terminal board 62 can be set to be substantially the same as the height of the LED chip A. Therefore, it is advantageous also in reducing the entire thickness of the mounting portion of the LED chip A and the electrical connection portion related thereto.
[0049]
Further, in the above structure, each part such as the LED chip A and the terminal plate 62 can be appropriately protected by the sealing resin 63, and the presence of the sealing resin 63 allows the terminal plate 62 and the electrode 4 to be protected. It is also possible to fix the positional relationship and maintain their conduction state appropriately. Of course, instead of means for resin-sealing the entire LED chip A and terminal plate 62, means for resin-sealing only the contact portion between the electrode 4 and the terminal plate 62 may be employed.
[0050]
In a state where the LED chip A is mounted as shown in FIG. 9, when a current is passed between the electrode 4 and the alternative support material 1, light is emitted from the light emitting layer 3 b of the semiconductor stacked portion 3 in the vertical direction. Released. Among these lights, upward light passes through the transparent electrode 4 and the sealing resin 63 as it is and proceeds upward. On the other hand, when the downward light reaches the surface of the light reflection layer 2, it is reflected upward with high reflectivity, and thereafter passes through the electrode 4 and the sealing resin 63 and travels upward. Therefore, the light emitted from the light emitting layer 3b can be eliminated from being absorbed by the alternative support material 1, and the amount of light emitted from the upper surface of the LED chip A can be increased. Further, when the light inside the semiconductor stacked portion 3 passes through the rough surface 30 of the n-type InGaAlP layer 3a, the light is in a scattering state. Therefore, the brightness of the LED chip A can be further increased.
[0051]
10 to 13 show other examples of the optical semiconductor chip according to the present invention. FIGS. 10 to 12 are sectional views, and FIG. 13 is a perspective view. For convenience of explanation, in these drawings, the same parts as those in the previous embodiment are denoted by the same reference numerals, and the description thereof is omitted.
[0052]
Unlike the LED chip A of the previous embodiment, the LED chip Aa shown in FIG. 10 has a configuration in which an electrode 4 a having translucency is partially provided on the semiconductor stacked portion 3. The LED chip Aa having such a configuration masks the surface of gold when the gold is deposited on the surface of the semiconductor laminate 3 by vapor deposition or sputtering, and the gold is deposited only on a predetermined portion of the surface 30. What should I do? Also in the LED chip Aa, as in the LED chip A of the previous embodiment, the electrical connection having the structure shown in FIG. 9 in which the terminal plate 62 is in contact with the upper surface of the electrode 4a can be performed. Of course, the present invention does not ask at all for the configuration of the electrical connection structure of the optical semiconductor chip. Therefore, it does not matter if wire bonding such as gold wire is applied to the electrode 4a.
[0053]
The LED chip Ab shown in FIG. 11 uses a metallic film having gloss on the surface as the alternative support material 1a. According to such a configuration, unlike the previous two LED chips A and Aa, the light emitted from the semiconductor laminated portion 3 can be replaced with the light without providing the light reflecting layer 2 on the surface of the alternative support material 1a. It can be efficiently reflected upward by the surface of the support material 1a. Moreover, if the metal film which has electroconductivity is used, the said alternative support material 1a can also be utilized as an electrode of the semiconductor lamination | stacking part 3 as it is.
[0054]
The LED chip Ac shown in FIG. 12 uses a transparent film as the alternative support material 1b. According to such a configuration, a part of the light emitted from the light emitting layer 3b of the semiconductor laminated portion 3 can be emitted from the upper surface to the outside, and the other part of the light is transmitted through the alternative support material 1b. Thus, the light can be emitted from the lower surface to the outside, and light can be emitted from the upper and lower surfaces of the LED chip Ac.
[0055]
Thus, in this invention, the specific material etc. of an alternative support material are not limited, A various thing can be used. If the alternative support material is formed of a synthetic resin film, a metal film, or the like, the material cost can be reduced and the manufacture thereof can be facilitated. However, the present invention is not limited to this. In the present invention, for example, a material such as a metal may be formed and solidified on one surface of the semiconductor laminated portion 3 by vapor deposition or sputtering, and a film-like substance obtained by this film forming process may be used as an alternative support material. Furthermore, for example, after applying a liquid material such as a resin to one surface of the semiconductor laminated portion 3, the material may be cured to form a film-like member, which may be used as an alternative support material.
[0056]
The optical semiconductor chip Ad shown in FIG. 13 is configured as an LD chip, and has a structure in which a semiconductor laminated portion 3A constituting a laser diode is bonded onto an alternative support material 1c. The semiconductor stacked portion 3A includes an n-type semiconductor layer 3e, an active layer 3f, a p-type semiconductor layer 3g, and the like, and is configured to be capable of laser oscillation by flowing a predetermined current in the thickness direction thereof. Yes. The semiconductor stacked portion 3A is manufactured by crystal growth of a compound semiconductor on a predetermined substrate, similar to the semiconductor stacked portion of the LED chip described above. The substrate used for crystal growth is removed, and instead, an alternative support material 1c is provided. As this alternative support material 1c, various materials can be used as in the case of the LED chip described above. An electrode is formed on the upper surface of the semiconductor stacked portion 3A as necessary.
[0057]
Also in the LD chip Ad, as in the previous LED chip A, the substrate used for crystal growth is removed, and a thin alternative support material 1c is provided instead, so that the overall thickness is considerably reduced. can do. Further, the presence of the alternative support material 1c can increase the strength of the entire LD chip, and it is possible to eliminate the problem that each part is easily damaged during the handling.
[0058]
Thus, the optical semiconductor chip according to the present invention is not limited to being configured as an LED chip, but can also be configured as an LD chip. The point is that the present invention can be applied to any optical semiconductor chip provided with a semiconductor laminated portion made of a compound semiconductor crystal regardless of its type. Needless to say, the specific components of the semiconductor stacked portion constituting the light emitting diode, the laser diode, etc. are not limited.
[0059]
Further, each operation process of the method for manufacturing an optical semiconductor chip according to the present invention is not limited to the above-described embodiment. The type of substrate used for crystal growth of the compound semiconductor may be appropriately selected according to the specific component contents of the compound semiconductor, and a semiconductor substrate such as a GaP substrate, a GaAlAs substrate, or a Si substrate may be used instead of the GaAs substrate. It may be used. For example, when manufacturing a blue LED, an alumina substrate (sapphire substrate) may be used.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an LED chip as a specific example of an optical semiconductor chip according to the present invention.
FIG. 2 is a fragmentary cross-sectional view showing a process for producing a semiconductor laminated portion on a substrate.
FIG. 3 is a cross-sectional view of a principal part showing a step of producing a light reflecting layer on a semiconductor laminated portion.
FIG. 4 is a cross-sectional view of a principal part showing a step of bonding an alternative support material to a semiconductor laminated portion through a light reflecting layer.
FIG. 5 is a fragmentary cross-sectional view showing a step of deleting a substrate used for crystal growth.
FIG. 6 is a fragmentary cross-sectional view showing a state where an etching process has been performed on the surface of a semiconductor stacked portion.
FIG. 7 is a cross-sectional view of a principal part showing a state in which an electrode is formed on the surface of a semiconductor laminated portion.
FIG. 8 is a cross-sectional view of an essential part showing a step of cutting a semiconductor laminated portion and an alternative support material into chips.
FIG. 9 is a cross-sectional view of a principal part showing an example of a mounting structure of the LED chip shown in FIG. 1;
FIG. 10 is a cross-sectional view showing another example of an optical semiconductor chip according to the present invention.
FIG. 11 is a cross-sectional view showing another example of an optical semiconductor chip according to the present invention.
FIG. 12 is a cross-sectional view showing another example of the optical semiconductor chip according to the present invention.
FIG. 13 is a perspective view showing another example of an optical semiconductor chip according to the present invention.
FIG. 14 is a cross-sectional view showing an example of a conventional LED chip.
[Explanation of symbols]
1, 1a-1c Alternative support material 2 Light reflection layer 3 Semiconductor laminated part (light emitting diode)
3A Semiconductor stack (laser diode)
4, 4a Electrode 5 GaAs substrate 30 Surface A, Aa to Ac LED chip (optical semiconductor chip)
Ad LD chip (Optical semiconductor chip)

Claims (6)

An optical semiconductor chip having a semiconductor laminated portion made of a compound semiconductor crystal,
The semiconductor laminated portion is bonded to an alternative support material different from the substrate used for the crystal growth, and the substrate is removed from the semiconductor laminated portion ,
The semiconductor laminated portion is configured as a light emitting diode, and is entirely formed as an LED chip.
The said alternative support material is a film which has translucency , The optical semiconductor chip characterized by the above-mentioned . The optical semiconductor chip according to claim 1, wherein the alternative support material has flexibility. The alternative supporting member has a conductive, optical semiconductor chip according to claim 1 or 2. 4. The optical semiconductor chip according to claim 1, wherein a surface opposite to a surface to which the alternative support material of the semiconductor laminated portion is bonded is an uneven rough surface. 5. Above semiconductor lamination portion the alternate support and the surface being adhesive opposite face entire or part of the, the electrode having a light transmitting property is provided, in any one of claims 1 to 4 The optical semiconductor chip described. The optical semiconductor chip according to claim 5 , wherein the electrode is a gold thin film layer.

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