JP2005109208A - Method of manufacturing light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing light emitting element by which a compound semiconductor layer containing a light emitting layer can be stuck surely to an element substrate without causing cracking nor chipping even when the semiconductor layer is extremely thin and warps. <P>SOLUTION: A laminate 130 is produced by laminating a compound semiconductor layer 50 and the element substrate 7 upon another. Then the laminate 130 is disposed between first and second pressurizing members 51 and 52 respectively having metallic main bodies 51a and 52a, in a state where pressurizing cushion layers 150 and 111 composed of a thermoplastic macromolecular material are interposed at least between the metallic main body 51a of the first pressurizing member 51 and the first principal surface of the laminate 130 or between the metallic main body 52a of the second pressurizing member 52 and the second principal surface of the laminate 130. Then the compound semiconductor layer 50 is stuck to the element substrate 7 by pressurizing the laminate 130 through the softened pressurizing cushion layers 150 and 111 between the first and second pressurizing members 51 and 52, while the laminate 130 is heated to a sticking temperature at which the cushion layers 150 and 111 are softened. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

JP 2001-339100 A JP 2001-68731 A

  When trying to increase the brightness of a light emitting element such as a light emitting diode or a semiconductor laser, the light extraction efficiency from the element is extremely important. In various publications including Patent Document 1, a growth GaAs substrate is removed, and a reinforcing Si substrate (having conductivity) is bonded to a removal surface through a reflective Au layer. Technology is disclosed. This Au layer has a high reflectivity, and since the dependency of the reflectivity on the incident angle is small, it is advantageous for improving the light extraction efficiency. Further, Patent Document 2 discloses a method of once peeling a GaAs substrate and newly bonding a transparent element substrate such as GaP that is transparent in the emission wavelength region in order to extract light from both sides of the light emitting layer portion. Yes.

  In the above method, a step of bonding a thin compound semiconductor layer including a light emitting layer portion and a current diffusion layer to an element substrate made of a semiconductor or metal is essential. In general, a group III-V compound semiconductor frequently used in a light-emitting element has a characteristic that it is brittle and easily chipped, and when a thin compound semiconductor layer is bonded to an element substrate, the pressure applied is not uniform. Then, there is a problem that the compound semiconductor layer is very easily cracked or chipped and directly connected to a defect. In addition, the compound semiconductor layer may be warped due to a mismatch in lattice constant with the growth substrate, a difference in linear expansion coefficient, or the like, but the above cracks and chips are more likely to occur due to such warpage. There is a tendency.

  An object of the present invention is to reliably perform bonding to an element substrate without causing cracks or chipping even when a compound semiconductor layer including a light emitting layer portion is thin and warps. It is providing the manufacturing method of a light emitting element.

Means for Solving the Problems and Effects of the Invention

The method for manufacturing a light-emitting device of the present invention is for manufacturing a light-emitting device in which an element substrate is bonded to a compound semiconductor layer made of a III-V group compound semiconductor having a light-emitting layer portion. ,
A laminated body in which a compound semiconductor layer and an element substrate are overlaid is created, and the metal body and the laminated body of the first pressure member between the first pressure member and the second pressure member each having a metal body. A pressure cushion layer made of a thermoplastic polymer material is interposed between at least one of the first main surface and between the metal main body of the second pressure member and the second main surface of the laminate. The laminated body is arranged in the above and the laminated body is heated between the first pressure member and the second pressure member while the laminated body is heated to the bonding temperature at which the pressure cushion layer is softened. The compound semiconductor layer and the element substrate are bonded to each other by applying pressure through the cushion layer.

  In order to securely bond the thin compound semiconductor layer to the element substrate, it is necessary to overlap the compound semiconductor layer and the element substrate so as to adhere to each other, and to apply pressure uniformly to the bonding surface in this state. At this time, the factors that cause cracking and chipping in the compound semiconductor layer are summarized in that the in-plane distribution of the bonding pressure becomes non-uniform. Factors that cause such non-uniform bonding pressure include non-uniform thickness and warpage occurring in the element substrate and the compound semiconductor layer. The non-uniform thickness of the element substrate is often caused by non-uniform grinding, polishing or epitaxial growth. If grinding, polishing, or epitaxial growth becomes uneven, the main surfaces of the substrate will not be parallel to each other, and one will be inclined with respect to the other, resulting in uneven substrate thickness corresponding to the direction of the inclination. Even after the compound semiconductor layers are stacked to form a laminated body, the thickness of the laminated body becomes nonuniform and is inherited. Further, the problem of warpage is likely to occur in a compound semiconductor layer heteroepitaxially grown on a growth substrate due to a mismatch in lattice constant between the growth substrate and the epitaxial layer, a difference in linear expansion coefficient, or the like. In either case, the pressure surface of the pressure member is biased against the thick part of the laminated body or the protruding part due to warping, so that the load tends to concentrate, which is a direct factor of cracking or chipping of the compound semiconductor layer. It is.

  Therefore, in the present invention, a pressure cushion layer made of a thermoplastic polymer material is interposed between the metal main body of at least one of the pressure members and the laminate, and the thermoplastic polymer material is softened. The temperature is set and the pressure cushion layer is softened at the time of bonding. Then, bonding is performed by pressing the laminate between the first pressure member and the second pressure member at the bonding temperature through the softened pressure cushion layer. Since the softened pressure cushion layer exhibits fluidity, the laminated body (or between the laminated body and the pressure member) can be pressed by bonding even if the laminated body has uneven thickness or warpage. Another member intervening: for example, deformed to follow a contact surface with a temporary support substrate (to be described later) bonded to the compound semiconductor layer, and as a result, a uniform pressure is applied to the laminate in the in-plane direction. Can do. Therefore, even when the compound semiconductor layer to be bonded is very thin, the occurrence of cracks and chips due to the effects of uneven thickness and warping as described above can be extremely effectively prevented or suppressed.

  In particular, when the compound semiconductor layer forming the laminate is warped, it can be bonded to the element substrate while correcting the warp by applying a uniform pressure through the pressure cushion layer. become. Specifically, the warpage occurring in the compound semiconductor layer is defined as d (mm) as the main surface outer diameter of the compound semiconductor layer, and u (μm) as the displacement in the thickness direction of the warpage occurring in the compound semiconductor layer. When the u / d value falls within a range of 7 (μm / mm) or less, the use of the pressure cushion layer allows the compound semiconductor layer to be attached to the element substrate in a state in which generation of cracks is suppressed. Can be bonded while correcting the warp.

  The pressure cushion layer can be a polymeric material coating layer formed on the surface of the metal body (of the pressure member). By integrating the pressure cushion layer with the pressure surface of the pressure member in the form of a polymer material coating layer, it takes time to prepare the pressure cushion layer when placing the laminate between the pressure members. As a result, it is possible to improve the efficiency of the bonding process. On the other hand, the pressure cushion layer may be a polymer material sheet that is detachably inserted between the metal body and the laminate. If pressurization is repeated in a heated state, the pressure cushion layer gradually wears out and permanent deformation accumulates, so it is necessary to replace it at an appropriate number of times. If the pressure cushion layer is formed of the polymer material sheet as described above, it is very easy to replace it when the end of its life is reached. On the other hand, when forming as a polymer material coating layer, it is necessary to remove the old coating layer which has reached the end of its life by polishing or the like and re-form a new coating layer.

  Said polymeric material coating layer or polymeric material sheet can be comprised with a fluorine resin. Fluororesin has excellent heat resistance, maintains stability to relatively high temperatures in the atmosphere, does not easily react with metals, and has a small surface friction coefficient. Accordingly, it is difficult to cause a problem that the laminated body is damaged due to adhesion or rubbing of the resin to the laminated body, and deterioration due to reaction of the pressure member with the metal main body is hardly caused. Examples of the fluororesin usable in the present invention include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), 4-fluoroethylene-6-fluoropropylene copolymer (FEP), 4-fluoroethylene-par Fluoroalkyl vinyl ether copolymer (PFA), 4-fluoroethylene-ethylene copolymer (ETFE), polyvinyl fluoride (PVF), fluoroethylene-hydrocarbon vinyl ether copolymer, polychlorotrifluoroethylene (PCT), etc. Can be illustrated.

  On the other hand, a temporary support substrate is bonded to the first main surface side of the compound semiconductor layer via a polymer material bonding layer forming a pressure cushion layer, and the laminate is bonded to the first pressure member and the second together with the temporary support substrate. It is also possible to sandwich and heat between the pressing member. According to this method, in addition to the effect of the polymer material bonding layer functioning as a pressure cushion layer, the compound semiconductor layer when forming the laminate by bonding the temporary support substrate to the thin compound semiconductor layer Is extremely easy to handle. As a result, the damage probability of the compound semiconductor layer due to the handling failure is reduced, which contributes to the improvement of the manufacturing yield of the light emitting elements. When the total thickness of the compound semiconductor layer incorporated in the temporary support bonded body is as thin as 7 μm or more and 30 μm or less, the effect of using the temporary support substrate is particularly remarkable.

In the light emitting device, the light extraction surface side electrode is formed so as to cover a part of the first main surface which becomes the light extraction surface of the compound semiconductor layer, while the light emission layer portion is formed on the second main surface of the compound semiconductor layer. The element substrate may be bonded through a metal layer having a reflection surface that reflects the light of the light to the light extraction surface side. In this case, in the stacked body, the element substrate, the metal layer, and the compound semiconductor layer are stacked in this order, and the contact between the compound semiconductor layer and the metal layer is between the metal layer and the compound semiconductor layer. It can be formed as a laminated side bonded alloyed layer for reducing resistance. The light extraction efficiency of the light-emitting element can be improved by performing bonding through a metal layer having a high reflectance. In this case, in order to reduce the contact resistance between the compound semiconductor layer and the metal layer, it is essential to dispose the bonding metal layer between them and alloy them by heat treatment. Considering this, the method for manufacturing a light emitting device of the present invention can be carried out as follows using a temporary support substrate. Ie;
A compound semiconductor layer growth step of epitaxially growing the compound semiconductor layer on the first main surface of the growth substrate;
A light extraction surface side electrode forming step of forming a light extraction surface side electrode on the first main surface side of the compound semiconductor layer;
With the growth substrate attached to the second main surface side of the compound semiconductor layer, the temporary support substrate is bonded to the first main surface of the compound semiconductor layer on which the light extraction surface side electrode is formed, and then the growth substrate is attached. A temporary support bonded body forming step of forming a temporary support bonded body in which the compound semiconductor layer and the temporary support substrate are bonded by removing,
A bonding side bonding metal layer forming step of forming a bonding side bonding metal layer on the second main surface of the compound semiconductor layer exposed by removing the growth substrate;
A bonding side alloying heat treatment step in which a bonding side alloying heat treatment is performed in the state of a temporary support bonded body by alloying the bonding side bonding metal layer with the compound semiconductor layer to form a bonding side bonding alloyed layer;
After completion of the bonding-side alloying heat treatment, a metal layer is formed on the second main surface of the compound semiconductor layer by performing a bonding treatment by setting the bonding temperature to be lower than the bonding-side alloying heat treatment step. An element substrate bonding step of creating an element substrate bonded body in which the element substrates are bonded together,
A temporary support substrate separation step of separating the temporary support substrate from the element substrate bonded body is performed in this order.

  According to the above method, after the compound semiconductor layer is epitaxially grown on the first main surface of the growth substrate, the light extraction surface side electrode is further formed on the first main surface side. Then, a temporary support substrate is bonded to the first main surface of the compound semiconductor layer on which the light extraction surface side electrode is formed through, for example, a polymer material bonding layer, and the growth substrate is removed by chemical etching or the like. . Since the temporary support substrate is bonded to the compound semiconductor layer as a reinforcing body even if the growth substrate is removed, the compound semiconductor layer is damaged by a bubble attack or the like during etching. Defects can be effectively prevented.

  In the case of a compound semiconductor layer made of a III-V group compound semiconductor, the bonding metal layer has, for example, Au, Ag or Al as a main component (50% by mass or more), and Ge, Sb, Sn, Be and What contains 1 type (s) or 2 or more types of Zn can be used. AuGe, AuGeNi, AuSn, and AuSb are excellent in the contact resistance reduction effect with the n-type semiconductor layer, and AuZn and AuBe are excellent in the contact resistance reduction effect with the p-type semiconductor layer. Such alloying heat treatment for the bonding metal layer is preferably performed at a temperature of 300 ° C. or higher and 450 ° C. or lower. If the alloying heat treatment temperature is less than 300 ° C., alloying between the compound semiconductor layer and the bonding metal layer does not proceed sufficiently, leading to an increase in contact resistance. On the other hand, the effect of alloying is saturated at a temperature higher than 450 ° C., but rather, the temperature is unnecessarily high from the viewpoint of preventing diffusion of alloy components into the light emitting layer and diffusion deterioration of the dopant concentration profile in the light emitting layer. Since it is not a good idea to set, the upper limit of the temperature of the alloying heat treatment is set to 450 ° C. Also, since the alloying heat treatment temperature is relatively high, the treatment is performed in an inert gas atmosphere such as argon or nitrogen in order to prevent oxidative degradation of the compound semiconductor layer.

  According to the above method, after forming the bonded-side bonding metal layer on the second main surface of the compound semiconductor layer from which the growth substrate has been removed, the alloying heat treatment is first performed, and then the second of the compound semiconductor layer is performed. An element substrate is bonded to the main surface via a metal layer. As a result, the thermal history of the alloying heat treatment is not applied to the bonding metal layer in contact with the bonding side bonding metal layer, and the components of the bonding side bonding metal layer are diffused and reflected in the metal layer surface. It is possible to effectively prevent problems that reduce the rate.

  Also, the light extraction side alloying for alloying the light extraction surface side electrode itself or the light extraction surface side bonding metal layer disposed between the light extraction surface side electrode and the compound semiconductor layer and the compound semiconductor layer Heat treatment is performed before the element substrate bonding step. As a result, the contact resistance between the light extraction surface side electrode and the compound semiconductor layer can be sufficiently reduced. Since the alloying heat treatment of the light extraction surface side electrode is also performed before the bonding of the element substrates, the thermal history causes the problem that the components of the bonding side bonded metal layer diffuse into the metal layer surface and reduce the reflectance. Can be prevented. In addition, alloying between the second main surface side of the compound semiconductor layer and the reflective surface side of the reflective metal layer is also suppressed, and this also contributes to an improvement in reflectance.

The timing of performing the light extraction side alloying heat treatment may be before the element substrate bonding step, and can be selected from the following various patterns:
(1) Perform before bonding the temporary support substrate;
(2) After the temporary support substrate is bonded, separately before the bonding-side alloying heat treatment step;
(3) The bonding side alloying heat treatment step is also used as the light extraction side alloying heat treatment.
Of these, it is clear that the process (3) contributes most to man-hour reduction.

  In the temporary support bonded body forming step, the temporary support substrate can be bonded to the compound semiconductor layer via the polymer material bonding layer. In this case, in the temporary support substrate separation step, the temporary support substrate can be separated from the element substrate bonded body by heating and softening the polymer material bonding layer. Since the polymer material bonding layer is composed of a thermoplastic polymer material (including wax), it can be easily applied onto the compound semiconductor layer, and when the temporary support substrate is no longer necessary in the process, It can be easily separated from the compound semiconductor layer by heating and softening the polymer material bonding layer.

  The pressure cushion layer is formed between the metal body of the pressure member and the laminate (or the temporary support substrate) together with the polymer material bonding layer for bonding the temporary support substrate to the laminate (the compound semiconductor layer). It is also possible to use in combination with the above-described polymer material coating layer or polymer material sheet disposed in the above. Thereby, it can suppress more effectively that a crack, a chip | tip, etc. arise in a compound semiconductor layer at the time of bonding.

  Next, in the method for manufacturing a light-emitting element according to the present invention, it is desirable to start increasing the pressure of bonding to the laminate after heating and softening the polymer material bonding layer. According to this method, the polymer material bonding layer is softened in advance and the fluidity is increased, and then the pressure increase of the bonding pressure is started, thereby further enhancing the effect of equalizing the pressure applied to the laminate. As a result, cracking of the compound semiconductor layer contained in the laminate can be effectively prevented.

  Moreover, a Si substrate can be used as the element substrate. In this case, a first Au-based metal layer that should be a part of the metal layer is formed on the second main surface of the compound semiconductor layer, and a second Au that should be a part of the metal layer on the bonding surface of the Si substrate. It is possible to adopt a method in which a metal system layer is formed and the first Au system metal layer and the second Au system metal layer are bonded together by bonding. The Si substrate can easily ensure sufficient conductivity as a light emitting element by doping, and is inexpensive. Further, the bonding between the first Au-based metal layer and the second Au-based metal layer has an advantage that a sufficient bonding strength can be easily obtained even at a relatively low temperature because the affinity between the Au-based metal layers is strong. . In addition, Au and Si are likely to cause metallurgical reaction (specifically, eutectic reaction: eutectic temperature of Au—Si binary system is 363 ° C.) at a relatively low temperature. Adopting the bonding process enables bonding at a temperature lower than the temperature at which such a reaction occurs, so that the problem that the state of the reflecting surface is impaired by the metallurgical reaction between the Si substrate and the Au-based metal layer can be avoided. There is. In order to further reduce the bonding temperature, it is desirable that the Au content of both the first Au-based metal layer and the second Au-based metal layer is 95% by mass or more.

  In this case, the second Au-based metal layer before the bonding is completed has a thermal history that is lower than the eutectic reaction temperature and higher than room temperature, such as the softening treatment of the pressure cushion layer described above. May join. In this case, even if the Si substrate and the second Au-based metal layer do not react with each other, the diffusion rate of Si atoms in Au is relatively high, so that Si springs up on the surface of the second Au-based metal layer due to diffusion. There is. In this case, when the bonding process is performed in the atmosphere, Si that is springed up on the surface of the second Au-based metal layer is oxidized, and the bonding strength with the first Au-based metal layer may be significantly reduced. Therefore, it is desirable to form a Si diffusion prevention layer between the Si substrate and the second Au-based metal layer for preventing the Si component from the Si substrate from diffusing into the second Au-based metal layer. Providing such a Si diffusion blocking layer effectively suppresses Si from springing up due to diffusion in the second Au-based metal layer, and consequently, a reduction in bonding strength with the first Au-based metal layer. Can do. As such a Si diffusion blocking layer, it contained a metal layer mainly composed of any one of Ti, Ni and Cr, or a Si diffusion blocking component consisting of one or more of Sn, Pb, In and Ga. A metal layer mainly composed of Au or Ag can be preferably used. Note that the bonding heat treatment is performed in an atmosphere inert to Si oxidation such as argon or nitrogen, so that even if Si diffuses slightly on the surface of the second Au-based metal layer, the bonding with the first Au-based metal layer can be performed. If the alignment can be performed without any problem, the Si diffusion blocking layer can be omitted.

  In order to further reduce the bonding temperature, either a polymer material coating layer or a polymer material sheet and a polymer material binding layer are used in combination as a pressure cushion layer, and a high polymer material binding layer is used. A material having a softening temperature lower than that of the thermoplastic polymer material forming the molecular material coating layer or the polymer material sheet can be employed. Then, the laminated body is heated to an intermediate temperature that is equal to or lower than the bonding temperature and the polymeric material bonding layer is softened, and after the intermediate temperature is reached, pressure increase of the bonding pressure to the laminated body is started, and the pressure increase starts. Later, the laminate is heated from the intermediate temperature toward the bonding temperature. In the state where the temperature of the laminate does not rise so much by sufficiently softening the polymer material bonding layer by heating to the intermediate temperature and starting the pressure increase toward the final set pressure of the bonding pressure in that state The applied pressure can be applied uniformly between the two Au-based metal layers. As a result, clean main surfaces of the first Au metal layer and the second Au metal layer are kept in close contact with each other while suppressing Si diffusion from the Si substrate side to the Au metal layer. Can do. Then, by further raising the temperature of the laminate from the intermediate temperature to the bonding temperature in the course of the pressurization, the first Au-based metal layer and the second Au-based metal layer that are in close contact with each other in a clean state are obtained. Diffusion bonding can be performed, and a strong bonding state can be obtained in a relatively short time. The effect can be further enhanced by starting the pressure increase of the bonding pressure to the laminate while keeping the laminate at an intermediate temperature.

  Specifically, the bonding pressure is set to 5 kPa to 1000 kPa, the bonding temperature is set to 200 ° C. to 280 ° C., and the holding time at the set pressure is set to 10 minutes to 60 minutes. It is desirable. As described above, in order to increase the adhesion between the Au-based metal layers formed on the compound semiconductor layer side and the Si substrate side, respectively, the polymer material bonding layer is pressurized in a moderately softened state, resulting in a laminate. It is important to deform following the uneven thickness and warpage. When the set pressure is less than the lower limit, it is difficult to obtain a uniform bonded state due to insufficient pressure. In addition, when the bonding temperature is less than the above lower limit value, the interdiffusion rate between Au-based metal layers for forming the bonding state decreases, and the softening of the polymer material bonding layer tends to be insufficient, It becomes difficult to obtain a uniform bonded state. In addition, if the holding time is less than 10 minutes, the interdiffusion between the Au-based metal layers is uniform over the entire bonding surface, coupled with the fact that the flow for the follow-up deformation of the polymer material bonding layer tends to be insufficient. It becomes difficult to proceed to the end, and as a result, a uniform bonded state cannot be obtained.

  On the other hand, when the final pressure exceeds the upper limit, the thin compound semiconductor layer is likely to be cracked or cracked. Moreover, when the bonding temperature exceeds the upper limit value, defects such as a decrease in reflectance are likely to occur due to Si diffusion from the Si substrate. Moreover, it is not desirable that the holding time exceeds 60 minutes in view of the efficiency of the bonding process.

  Hereinafter, an embodiment of a method for manufacturing a light emitting device according to the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a light emitting element to which the present invention is applied. The light emitting device 100 includes an Au-based metal layer 10 as a metal layer on a first main surface of a Si substrate 7 (in this embodiment, n-type but may be p-type) made of silicon single crystal as an element substrate. It has a structure in which the light-emitting layer portion 24 is bonded via. In the present embodiment, as shown in FIG. 1, the main surface of the layer or the substrate is a state where the light extraction surface PF of the light emitting element 100 is on the upper side, and the surface appearing on the upper side in the normal state is the first main surface. The surface, the surface appearing on the lower side, is uniformly described as the second main surface. Therefore, for convenience of description of the process, when the drawing is performed in a transposed state that is upside down with respect to the normal state, the vertical relationship between the first main surface and the second main surface in the drawing is also reversed.

The light emitting layer portion 24 is an active layer 5 made of a non-doped (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 0.55, 0.45 ≦ y ≦ 0.55) mixed crystal. a first-conductivity-type cladding layer, in this embodiment the p-type cladding layer 6 made of p-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1), the first conductivity type the second-conductivity-type cladding layer different from the clad layer, in this embodiment interposed by an n-type _{(Al z Ga 1-z)} y in 1-y P ( except x <z ≦ 1) p-type clad layer 4 made of According to the composition of the active layer 5, the emission wavelength can be adjusted in the green to red region (the emission wavelength (peak emission wavelength) is 550 nm or more and 670 nm or less).

  A current diffusion layer 20 made of AlGaAs (AlInP may be used) is formed on the first main surface of the light emitting layer portion 24, and constitutes a compound semiconductor layer 50 together with the light emitting layer portion 24. A light extraction surface side electrode 9 (for example, an Au electrode) for applying a light emission driving voltage to the light emitting layer portion 24 is formed substantially at the center of the first main surface of the current diffusion layer 20. Between the light extraction surface side electrode 9 and the current diffusion layer 20, an AuBe bonding alloyed layer 9a (for example, Be: 2% by mass) as a light extraction side bonding alloyed layer is disposed. A region around the light extraction surface side electrode 9 on the first main surface of the current diffusion layer 20 forms a light extraction region PF from the light emitting layer portion 24. The entire light extraction surface side electrode 9 can be made of an AuBe alloy. Further, in the present embodiment, the p-type cladding layer 6 is a laminated form in which it is located on the light extraction surface side, but it may be a laminated form in which the n-type cladding layer 4 is located on the light extraction surface side (in this case, current diffusion) The layer 20 must be n-type, and the bonded alloying layer 9a is made of AuGeNi or the like).

  The thickness of the n-type cladding layer 4 and the p-type cladding layer 6 is, for example, 0.8 μm or more and 4 μm or less (preferably 0.8 μm or more and 2 μm or less), and the thickness of the active layer 5 is 0.4 μm or more and 2 μm, for example. Or less (desirably 0.4 μm or more and 1 μm or less). The total thickness of the light emitting layer portion 24 is, for example, 2 μm to 10 μm (desirably 2 μm to 5 μm). Furthermore, the thickness of the current spreading layer 20 is, for example, 5 μm or more and 28 μm or less (desirably 8 μm or more and 15 μm or less). Therefore, the thickness of the compound semiconductor layer 50 is, for example, 7 μm or more and 38 μm or less (desirably 5 μm or more and 20 μm or less). If the thickness of the current diffusion layer 20 is less than 5 μm, the in-plane current diffusion effect may be reduced and the light extraction efficiency may be reduced. On the other hand, when the thickness of the current diffusion layer 20 exceeds 28 μm, dopant diffusion into the active layer 5 of the light emitting layer portion 24 proceeds due to thermal history when the current diffusion layer 20 is epitaxially grown, leading to a decrease in light emission efficiency. There is. In the present embodiment, the p-type cladding layer 6 is a laminated form in which the light-extracting surface is located, but the n-type clad layer 4 may be in a laminated form in which it is located on the light-extracting side (in this case, current diffusion). The layer 20 must be n-type, and the bonded alloying layer 9a is made of AuGeNi or the like).

  On the other hand, a back electrode (for example, an Au electrode) 15 is formed on the back surface of the Si substrate 7 so as to cover the whole. An AuSb bonding alloyed layer 16 is interposed between the back electrode 15 and the Si substrate 7 as a substrate side bonding alloyed layer. Instead of the AuSb bonding alloyed layer 16, an AuSn bonding alloyed layer may be used as the substrate side bonding alloyed layer.

  The Si substrate 7 is manufactured by slicing and polishing a Si single crystal ingot, and the thickness thereof is, for example, 100 μm or more and 500 μm or less. Then, it is bonded to the light emitting layer portion 24 with the Au-based metal layer 10 interposed therebetween. The Au-based metal layer 10 is formed by laminating the first Au-based metal layer 10a on the compound semiconductor layer 50 side and the second Au-based metal layer 10b on the Si substrate 7 side. One Au-based metal layer. The first Au-based metal layer 10a and the second Au-based metal layer 10b (and thus the Au-based metal layer 10) are made of pure Au or an Au alloy having an Au content of 95% by mass or more.

  An AuGeNi bonding alloyed layer 31 (for example, Ge: 15% by mass, Ni: 10% by mass) is formed between the light emitting layer part 24 and the first Au-based metal layer 10a as a bonding side bonding alloyed layer. This contributes to reducing the series resistance of the element. The AuGeNi bonding alloyed layer 31 is dispersedly formed on the first main surface of the first Au-based metal layer 10a, and the formation area ratio (AuGeNi bonding alloying with respect to the entire first main surface area of the first Au-based metal layer 10a) is formed. The ratio of the total area of the layer 31 is 1% or more and 25% or less. Further, an AuSb bonding alloyed layer 32 (for example, Sb: 2% by mass) is interposed between the Si substrate 7 and the second Au-based metal layer 10b as a substrate-side bonding alloyed layer. Instead of the AuSb bonding alloyed layer 32, an AuSn bonding alloyed layer may be used.

  In the present embodiment, the entire surface of the AuSb bonding metal layer 32 is prevented from diffusing the Si component from the Si substrate 7 into the Au-based metal layer 10 during the bonding heat treatment described later (specifically, It is a Ti layer). The thickness of the Si diffusion blocking layer 10c is 1 nm or more and 10 μm or less (200 nm in this embodiment). Si may be composed of a Ni layer or a Cr layer instead of the Ti layer. The Au-based metal layer 10 (second Au-based metal layer 10b) is disposed so as to be in contact with the entire surface of the Si diffusion blocking layer 10c.

  In this embodiment, the Au-based metal layer 10 that forms the metal layer also serves as a reflective layer. The light from the light emitting layer portion 24 is extracted in a form in which the light reflected directly from the Au-based metal layer 10 is superimposed on the light emitted directly to the light extraction surface side. The thickness of the Au-based metal layer 10 is desirably 80 nm or more in order to ensure a sufficient reflection effect. Moreover, although there is no restriction | limiting in particular in the upper limit of thickness, since a reflection effect is saturated, it determines suitably (for example, 1 micrometer or less) by balance with cost. Note that an Ag-based layer can be used as the metal layer that also serves as the reflective layer. For example, instead of the first Au-based metal layer 10a and the second Au-based metal layer 10b, a first Ag-based layer and a second Ag-based layer can be formed and bonded together. In this case, the bonded side bonded alloyed layer can also be composed of an Ag-based material such as AgGeNi.

Hereinafter, a specific example of the method for manufacturing the light emitting device 100 will be described.
First, as shown in step 1 of FIG. 2, an n-type GaAs buffer layer 2 is 0.5 μm, for example, and a release layer 3 made of AlAs is 0.5 μm, for example, on the main surface of a GaAs single crystal substrate 1 that is a growth substrate. Then, epitaxial growth is performed in this order. Thereafter, as the light emitting layer portion 24, an n-type cladding layer 4 (thickness: for example 1 μm), an AlGaInP active layer (non-doped) 5 (thickness: for example 0.6 μm), and a p-type cladding layer 6 (thickness: for example 1 μm). ) In this order. The total thickness of the light emitting layer portion 24 is 2.6 μm. Further, a current diffusion layer 20 made of p-type AlGaAs is epitaxially grown by 5 μm, for example. Epitaxial growth of each of these layers can be performed by a known MOVPE method. The following can be used as a source gas that is a component source of Al, Ga, In, P, and As;
Al source gas; trimethylaluminum (TMAl), triethylaluminum (TEAl), etc .;
Ga source gas; trimethylgallium (TMGa), triethylgallium (TEGa), etc .;
In source gas; trimethylindium (TMIn), triethylindium (TEIn), etc.
P source gas; tertiary butyl phosphine (TBP), phosphine (PH ₃ ), etc.
As source gas; tertiary butyl arsine (TBA), arsine (AsH ₃ ), etc.

Moreover, as a dopant gas, the following can be used;
(P-type dopant)
Mg source: biscyclopentadienyl magnesium (Cp ₂ Mg), etc.
Zn source: dimethyl zinc (DMZn), diethyl zinc (DEZn), etc.
(N-type dopant)
Si source: silicon hydride such as monosilane.

  As a result, the compound semiconductor layer 50 including the light emitting layer portion 24 and the current diffusion layer 20 is formed on the GaAs single crystal substrate 1. The thickness of the compound semiconductor layer 50 is 7.6 μm. When the GaAs single crystal substrate 1 is removed, it is practically impossible to handle it alone without being damaged. At this stage, the AuBe bonding metal layer 9a '(light extraction surface side bonding alloyed layer) and the light extraction surface side electrode 9 covering the same are patterned on the first main surface of the compound semiconductor layer 50. Thereafter, the light extraction side alloying heat treatment may be subsequently performed to change the AuBe bonding metal layer 9a ′ into the bonding alloying layer 9a. However, in this embodiment, the light extraction side alloying heat treatment is performed using an Au-based metal layer 10a described later. This is also used for the bonding-side alloying heat treatment when the side AuGeNi bonding alloying layer 31 is formed.

  Next, as shown in Step 2, a polymer material bonding layer 111 (which also functions as a pressure cushion layer later) is applied to the first main surface of the compound semiconductor layer 50 so as to cover the light extraction surface side electrode 9. Attached. Then, as shown in step 3, with the polymer material bonding layer 111 heated and softened, a separately prepared temporary support substrate 110 is stacked and adhered, and then cooled to cure the polymer material bonding layer 111. By doing so, the temporary support bonded body 120 in which the compound semiconductor layer 50 and the temporary support substrate 110 are bonded to each other via the polymer material bonding layer 111 is formed (step 3). Alternatively, the temporary support bonded body 120 may be formed by applying the polymer material bonding layer 111 to the temporary support substrate 110 and bonding the compound semiconductor layer 50 thereto. At this time, the GaAs single crystal substrate 1 as a growth substrate is attached to the second main surface side of the compound semiconductor layer 50.

  The material of the temporary support substrate 110 is made of a material that maintains rigidity even during an alloying heat treatment described later and that generates less gas. Specifically, it can be composed of a Si substrate, a ceramic plate (for example, an alumina plate), a metal plate, or the like. The thickness is, for example, 100 μm or more and 500 μm or less, but may be thicker. On the other hand, hot-melt adhesives and waxes can be used as the polymer material bonding layer 111. Specifically, an alloy described later in a temperature range of 300 ° C. to 450 ° C. in an inert gas atmosphere. In order to avoid damage to the compound semiconductor layer 50 due to vaporization of the polymer material bonding layer 111 during the heat treatment, vapor pressure in the temperature range of 300 ° C. to 450 ° C. (equilibrium vapor measured under constant volume conditions) Pressure) is 10 torr or less. Examples of commercially available waxes suitable for the formation of the polymer material binding layer 111 include Apiezon Wax W (manufactured by M & I Materials Ltd.), Space Liquid (manufactured by Nikka Seiko Co., Ltd.), and protect wax. be able to.

  Next, as shown in step 4 of FIG. 3, the GaAs single crystal substrate 1 as a growth substrate attached to the temporary support bonded body 120 is removed. For this removal, for example, the temporary support bonded body 120 (see step 3) is immersed in an etching solution (for example, a 10% aqueous hydrofluoric acid solution) together with the GaAs single crystal substrate 1 and formed between the buffer layer 2 and the light emitting layer portion 24. The GaAs single crystal substrate 1 can be peeled from the temporary support bonded body 120 by selectively etching the AlAs release layer 3 thus formed. It should be noted that an etch stop layer made of AlInP is formed in place of the AlAs release layer 3, and a GaAs single crystal is used by using a first etching solution (for example, ammonia / hydrogen peroxide mixed solution) having selective etching properties with respect to GaAs. Etch and remove the substrate 1 together with the GaAs buffer layer 2 and then etch stop using a second etchant that has selective etching properties with respect to AlInP (for example, hydrochloric acid: hydrofluoric acid may be added to remove the Al oxide layer) A step of etching away the layer can also be employed.

  In this way, the compound semiconductor layer 50 from which the GaAs single crystal substrate 1 has been removed is bonded to the temporary support substrate 110 via the polymer material bonding layer 111 that also functions as a pressure cushion layer, and the temporary support bonded body. 120 is formed. Therefore, even though the compound semiconductor layer 50 is very thin, it is difficult to cause a problem of being destroyed by an impact such as bubbles when the GaAs single crystal substrate 1 is removed by etching, and temporary support sticking is performed even after the GaAs single crystal substrate 1 is removed. Since it is reinforced in the form of the mating body 120, it is possible to easily handle when it is used in the subsequent steps.

  As shown in FIG. 10, when the growth substrate 1 is removed without attaching the temporary support substrate 110, the compound semiconductor layer 50 epitaxially grown on the growth substrate 1 includes the growth substrate 1 and the growth substrate 1. Cause a strong warp due to residual stress caused by a mismatch in lattice constants, a difference in linear expansion coefficient, etc. (Note that the warp displacement u is determined from the apparent height H when the layer or substrate is placed on a horizontal plane. It is defined as a value obtained by subtracting the actual thickness t0). However, as shown in FIG. 11, if the temporary support substrate 110 with a small warp is bonded to the compound semiconductor layer 50 via the polymer material bonding layer 111 and the growth substrate 1 is removed in this state, the compound semiconductor layer 50 is corrected by being pulled by the temporary support substrate 110 in the plane, and the warp displacement u can be reduced. The warp displacement u (μm) of the temporary support bonded body 120 (and consequently the compound semiconductor layer 50 in the temporary support bonded body 120) after the growth substrate 1 is removed is outside the main surface of the compound semiconductor layer 50. Adjusting the epitaxial growth conditions and the composition and thickness of the light emitting layer portion 24 or the current diffusion layer 20 so that the diameter is d (mm) and the u / d value falls within the range of 7 (μm / mm) or less. It is desirable to keep it. In the AlGaInP compound constituting the light emitting layer portion 24, the lattice mismatch rate with the growth substrate 1 made of GaAs single crystal is reduced as much as possible in order to improve the internal quantum efficiency by minimizing crystal defects and the like. The composition is selected.

  Next, as shown in step 5, in the state of the temporary support bonded body 120, an AuGeNi bonded metal layer 31 ′ is formed on the second main surface of the compound semiconductor layer 50 exposed by removing the GaAs single crystal substrate 1 in a dispersed manner. Further, a bonding-side alloying heat treatment is performed so that the AuGeNi bonded metal layer 31 ′ becomes the AuGeNi bonded alloyed layer 31. At this time, the AuBe bonding metal layer 9a 'can be alloyed with the light extraction surface side electrode 9 at the same time (that is, also used for light extraction side alloying heat treatment).

The AuGeNi bonding metal layer 31 ′ is formed by sputtering or vacuum deposition in a vacuum atmosphere. Specifically, the film formation is performed under the conditions of a temperature of 60 ° C. or more and 150 ° C. or less and a degree of vacuum (pressure) of 1 × 10 ⁻⁶ torr or more and 1 × 10 ⁻⁴ torr or less (if necessary, temporary support bonding is performed) The laminated body 120 can be heated by a heater (not shown)). By adopting a polymer material bonding layer 111 having a vapor pressure of 1 × 10 ⁻⁶ torr or less in the above temperature range (the above-mentioned commercial product also satisfies this condition), the bonding metal layer 31 to be formed is formed. It is possible to effectively prevent a problem that the quality of 'deteriorates due to the gas from the polymer material bonding layer 111.

The alloying heat treatment is performed in an inert gas atmosphere at a temperature of 300 ° C. or higher and 450 ° C. or lower. Specifically, the alloying heat treatment can be performed in an inert gas atmosphere such as N _{2 at the} same level as atmospheric pressure. Since the polymer material bonding layer 111 to be used has a vapor pressure of 10 torr or less in the above temperature range, the compound semiconductor layer 50 can be effectively prevented from being damaged due to rapid vaporization of the polymer material bonding layer 111.

Further, by separately preparing the Si substrate 7, forming AuSb bonding metal layers on both main surfaces thereof, and further performing alloying heat treatment in a temperature range of 250 ° C. or higher and 360 ° C. or lower, respectively, the AuSb bonding alloyed layer 32 is obtained. , 16. Among these, on the AuSb bonding alloying layer 32, the Si diffusion preventing layer 10c for preventing the components of the Si substrate 7 from diffusing into the second Au-based metal layer 10b in the subsequent element substrate bonding step is formed. The alloying heat treatment of the AuSb bonding alloying layer 32 is performed after the Si diffusion blocking layer 10c is formed. On the other hand, the back electrode 15 is formed on the AuSb bonding alloying layer 16.
* It may be possible to form a Ti layer by sintering first. It's a little difficult to understand because of Si diffusion.

Next, an element substrate bonding step is performed. Specifically, as shown in Step 6 of FIG. 3, the first Au-based metal layer 10a is formed on the second main surface of the compound semiconductor layer 50 in the state of the temporary support bonded body 120, while the Si substrate A second Au-based metal layer 10 b is formed on the first main surface side of 7. Each Au-based metal layer can be formed in a vacuum atmosphere (by sputtering or vacuum vapor deposition). Specifically, film formation is performed under conditions of a temperature of 60 ° C. or more and 150 ° C. or less and a degree of vacuum (pressure) of 1 × 10 ⁻⁶ torr or more and 1 × 10 ⁻⁴ torr or less. When the first Au-based metal layer 10a on the temporary support bonded body 120 side is formed, a polymer material bonding layer 111 having a vapor pressure of 1 × 10 ⁻⁶ torr or less in the above temperature range is adopted. Accordingly, it is possible to effectively prevent a problem that the quality of the Au-based metal layer formed by the gas from the polymer material bonding layer 111 is deteriorated.

  Then, the first Au-based metal layer 10a of the temporary support bonded body 120 and the second Au-based metal layer 10b of the Si substrate 7 are overlapped. The compound semiconductor layer 50 is overlapped with the Si substrate 7 which is an element substrate to form a stacked body 130. Since the temporary support substrate 110 is bonded to the first main surface of the compound semiconductor layer 50 via the polymer material bonding layer 111, the stack 130 with the temporary support substrate 110 is attached to the temporary support stack 130 ′. I will call it. Then, the temporary support laminate 130 ′ is disposed between the first pressure member 51 and the second pressure member 52 in which the resistance heating heater 49 is built, and both pressures are applied while being heated by the resistance heating heater 49. The first Au-based metal layer 10a and the second Au-based metal layer 10b are bonded together by applying pressure between the members 51 and 52 (FIG. 5). The resistance heater 49 is embedded in the metal bodies 51a and 52a of the pressurizing members 51 and 52, and a thermoplastic fluororesin (in this embodiment, polytetrafluoroethylene (trademark) is provided on the pressurizing surfaces of the metal bodies 51a and 52a. A polymer material coating layer 150 as a pressure cushion layer made of a name: Teflon)) is formed with a thickness of, for example, 50 μm to 300 μm. The polymer material bonding layer 111 is selected to have a softening temperature lower than that of the polymer material coating layer 150 made of a fluororesin (for example, a glass transition temperature of 80 ° C. or higher and 90 ° C. or lower). ).

  FIG. 6 illustrates details of the bonding process, and FIG. 7 illustrates a control pattern of pressure and temperature during the bonding process. As shown in step 1 of FIG. 6, the resistance heater 49 is heated and heated to an intermediate temperature θ1 lower than the final bonding temperature θ2. The intermediate temperature θ1 is set, for example, in the range of 80 ° C. or more and 150 ° C. or less so that the polymer material bonding layer 111 (pressure cushion layer) to which the temporary support substrate 110 is bonded is softened. In this state, the temporary support laminate 130 ′ is disposed between the pressure members 51 and 52 until the temperature of the temporary support laminate 130 ′ (and thus the polymer material bonding layer 111) is stabilized at the intermediate temperature θ1. Wait a little.

  When the temperature of the temporary support laminated body 130 ′ reaches the intermediate temperature θ1, as shown in step 2, the pressure bonding to the temporary support laminated body 130 ′ is started in the state where the intermediate temperature θ1 is maintained. . This pressurization is performed by relatively bringing the pressure members 51 and 52 closer to each other by the drive mechanism. Since the polymer material bonding layer 111 is sufficiently softened in advance, the polymer material bonding layer 111 is deformed following the shape of the compound semiconductor layer 50 that is warped or has a non-uniform thickness. Thereby, it functions as a pressure transmission medium that uniformly transmits the applied pressure from the temporary support substrate 110 side in the plane, and is effective in preventing the compound semiconductor layer 50 from cracking. In particular, when the compound semiconductor layer 50 is warped and deformed, the restriction on the deformation of the compound semiconductor layer 50 is weakened by increasing the fluidity of the polymer material bonding layer 111, so that the crack prevention effect is more remarkable. Become. Note that if the rate of temperature increase near the intermediate temperature θ1 is reduced, isothermal holding at the intermediate temperature θ1 may not necessarily be performed.

It should be noted that both main surfaces of the temporary support laminate 130 ′ are caused by non-uniform thickness of the compound semiconductor layer 50, Si substrate 7 or temporary support substrate 110, non-uniform coating thickness of the polymer material bonding layer 111, etc. When the pressure members 51 and 52 are inclined, the pressure surfaces of the pressure members 51 and 52 can be obtained by using a hydraulic or mechanical uniaxial drive mechanism in which the pressure surfaces of the pressure members 51 and 52 are aligned with each other. Is biased to the main surface of the temporary support laminate 130 ′, and the non-uniformity of the applied pressure becomes significant. Therefore, as shown in FIG. 9, when the pressure surface normal line direction O2 of the _second pressure member 52 is configured to be variable and the two main surfaces of the temporary support laminate 130 ′ are inclined with respect to each other, The temporary support laminate 130 ′ of the second pressurizing member 52 so that the pressurizing surface normal O ₂ direction of the two pressurizing members coincides with the normal direction O ₄ of the second main surface of the temporary support laminate 130 ′. It is preferable to provide a pressurization drive mechanism 53 that performs pressurization while correcting the pressurization posture with respect to. If the pressing surface normal direction O ₁ of the first pressing member 51 is fixed, the pressing surface normal O ₁ direction of the first pressing member 51 is also normal to the first main surface of the temporary support laminate 130 ′. It becomes a state consistent with O ₃ . For example, the pressurization drive mechanism 53 is configured as a fluid pressurization mechanism that pressurizes the second pressurization member 52 from the opposite side facing the temporary support laminate 130 ′ via fluid pressure. Can do. The main part of the pressure drive mechanism 53 includes a filling space forming body 55 and a flexible sealing member 56. The filling space forming body 55 forms a filling space 54 of the pressurized fluid F on the opposite side of the second pressurizing member 52 facing the temporary support laminate 130 ′, and the second pressurizing member 52 forms a part of the partition wall of the filling space 54. The flexible sealing member 56 connects the filling space forming body 55 and the second pressurizing member 52 so as to seal the filling space 54, and when the pressurized fluid F is pressed into the filling space 54. The second pressure member 52 serves to absorb the change in the pressure posture of the temporary support laminate 130 ′. As the pressurized fluid F, a liquid such as oil or water may be used in addition to a gas such as air. By applying pressure of the pressurized fluid F to the filling space 54, the applied pressure can be adjusted to a desired value.

  Since the flow of the polymer material bonding layer 111 during pressurization is accompanied by a certain delay, if the pressure increase rate during pressurization is set too large, the polymer material bond layer that matches the shape of the compound semiconductor layer 50 The deformation of 111 cannot follow the pressure increase, and the compound semiconductor layer 50 is likely to be cracked. Accordingly, the boosting speed is set to, for example, 100 kPa / min or less, preferably 50 kPa / min or less so that such a problem does not occur. However, since excessively reducing the pressure increase rate also leads to a reduction in efficiency of the bonding process, it is desirable to set the pressure increase rate to 1 kPa / min or more.

  Temporary support laminated body 130 '(laminated body 130) is further heated from the intermediate temperature θ1 to the final bonding temperature θ2. The bonding temperature θ2 is 200 ° C. or more and 280 ° C. or less, and the diffusion between the two Au-based metal layers 10a and 10b proceeds sufficiently. On the other hand, the Si diffusion from the Si substrate 7 to the second Au-based metal layer 10b is It is set so that it does not proceed (the effect of suppressing Si diffusion from the Si substrate 7 by the Si diffusion blocking layer 10c is great) and the polymer material coating layer 150 forming the pressure cushion layer is softened. ing. As shown in FIG. 8, the polymer material coating layer in which the main surface side surface layer portion of the temporary support laminate 130 ′ that has warped is softened when bonding and pressurization is performed in a state where the polymer material coating layer 150 is softened. The polymer material coating layer 150 is deformed following the main surface shape of the temporary support laminate 130 ′. Thereby, the applied pressure of bonding can be more uniformly given with respect to the bonding interface of Au type metal layer 10a, 10b.

  Further, in the present embodiment, during the holding at the intermediate temperature θ1 lower than the bonding temperature θ2, the pressing of the bonding is started, and the intermediate pressure is delayed by a certain time (t1 in FIG. 7). The temperature rise from the temperature θ1 to the bonding temperature θ2 is started. Since the intermediate temperature θ1 is sufficiently low and the Si diffusion blocking layer 10c is provided in the present embodiment, Si diffusion from the Si substrate 7 to the second Au-based metal layer 10b does not proceed so much, and the first Au-based metal layer The bonding surface (first main surface) with 10a is also kept clean. In this state, by starting the pressing of the bonding, the Au-based metal layers 10a and 10b can be uniformly adhered without being contaminated by the Si diffusion.

  At the time of raising the temperature to the bonding temperature θ2, the temperature is increased to the final set pressure P3 (5 kPa or more and 1000 kPa or less) before the temperature distribution of the temporary support laminate 130 ′ (laminate 120) is not sufficiently stabilized. If the step is rapidly performed, the compound semiconductor layer 50 is likely to be cracked. The reason is that the deformation of the polymer material coating layer 150 cannot follow the pressure increase and the applied pressure becomes non-uniform, and the thermal stress generated inside the temporary support laminate 130 ′ due to the temperature distribution is further increased. This is presumed to overlap with this.

  In the present embodiment, as shown in FIG. 7, after reaching the intermediate pressure P2 lower than the final set pressure P3 after the start of pressure increase, the pressure increase is temporarily interrupted there, and the intermediate pressure P2 is maintained for a predetermined time. Only t2 is held (FIG. 6: step 3). During the holding at the intermediate pressure P2, the temperature increase from the intermediate temperature θ1 to the bonding temperature θ2 is started, and the pressure increase to the set pressure P3 is resumed in a form delayed by t2 from the start of the temperature increase. (It reaches the set pressure P3 at time t3). In other words, the temperature distribution of the temporary support laminate 130 ′ is stabilized by delaying the pressure increase to the set pressure P3 by holding at the intermediate pressure P2 and, in advance, increasing the temperature to the bonding temperature θ2 in the meantime. In other words, the compound semiconductor layer 50 can be cracked because the final pressurization to the preset pressure P3 can be continued in a state in which time can be saved and inconvenient stress generation due to uneven temperature distribution is suppressed. Can be effectively suppressed. Further, by maintaining at the intermediate pressure P2, the adhesion state of the Au-based metal layers 10a and 10b can be made more uniform.

  In the present embodiment, the intermediate pressure P2 is set to 50% or more and 70% or less of the final set pressure P3. When P2 is less than 50% of P3, the effect of improving the adhesion between the Au-based metal layers 10a and 10b becomes insufficient. On the other hand, when P2 exceeds 70% of P3, the compound semiconductor layer 50 is likely to be cracked. Further, the pressure increase rate from the intermediate pressure P2 to the final set pressure P3 is set to 1 kPa / min or more and 100 kPa / min or less as described above to reach the compound semiconductor layer 50. Cracking can be effectively prevented.

  When the temperature reaches the bonding temperature θ2 and the applied pressure reaches the set pressure P3, the temperature is maintained in the range of 10 minutes to 60 minutes. As a result, even if some warping occurs in the compound semiconductor layer 50 between the first Au-based metal layer 10a and the second Au-based metal layer 10b, it is extremely uniform over the entire surface without causing cracks or the like. A bonded state can be formed.

  The actions and effects of the above series of steps can be summarized as follows. That is, the pressure is gradually increased at an intermediate temperature θ1 of 80 ° C. or more and 150 ° C. or less under a condition controlled to 1 kPa / min or more and 100 kPa / min or less, and further, 50 of the set pressure P3 (5 kPa or more and 1000 kPa or less). By holding at an intermediate pressure P2 adjusted to not less than 70% and not more than 70%, the first Au-based metal layer 10a and the second Au-based metal layer 10b are uniformly distributed through the softened polymer material bonding layer 111. It can be adhered. At this time, Si diffusion from the Si substrate 7 to the second Au-based metal layer 10b is suppressed by the Si diffusion blocking layer 10c. Then, after starting the pressurization during the holding at the intermediate temperature θ1, the temperature rise toward the bonding temperature θ2 is resumed, thereby effectively suppressing the occurrence of cracks in the compound semiconductor layer 50 and temporarily supporting The laminated body 130 ′ can be made to reach the bonding temperature θ2 and the set pressure P3. Then, by holding in that state for 10 minutes or more and 60 minutes or less, the diffusion of the first Au-based metal layer 10a and the second Au-based metal layer 10b that are in close contact with each other can be diffused over the entire bonding surface. Over a wide range, and a very strong bonding state can be obtained. In addition, since the bonding temperature θ2 is set to 200 ° C. or higher and 280 ° C. or lower, the influence of Si diffusion from the Si substrate 7 is also reflected on the reflecting surface (first Au-based metal layer) as long as the holding time remains 60 minutes or shorter. 10a is formed), and good reflectance can be achieved.

  Since the first Au-based metal layer 10a and the second Au-based metal layer 10b are mainly composed of Au that is difficult to oxidize, the bonding heat treatment can be performed without any problem even in the atmosphere, for example. . Further, in the process of this embodiment, the alloying heat treatment on the light extraction side and the bonding side has already been completed at this stage, and the bonding heat treatment is performed at a lower temperature than that, so that the bonding alloyed layer is formed. Is effectively suppressed from diffusing into the surface of the reflecting surface made of the Au-based metal layer 10, and as a result, a reflecting surface with higher reflectivity can be obtained.

  When the bonding heat treatment is completed, a temporary support substrate separation step is performed. In the temporary support substrate separation step, as shown in Step 8 of FIG. 4, the polymer material bonding layer 111 is heated and softened, and the temporary support substrate 110 is separated and removed. Note that this separation can be performed simultaneously with the bonding heat treatment in step 7. Thereafter, as shown in Step 9, the polymer material bonding layer 111 remaining on the first main surface of the compound semiconductor layer 50 is dissolved and removed using an organic solvent such as toluene or methyl ethyl ketone (MEK).

  In the above, for the purpose of facilitating understanding, the process of forming the bonded assembly 130 has been described in the form of a single element stack, but in practice, a plurality of element chips are arranged in a matrix. A bonded wafer formed in a lump is created. Then, the bonded wafer is diced by an ordinary method to form an element chip, which is fixed to a support and subjected to wire bonding of a lead wire, etc., and then sealed with a resin to obtain a final light emitting element. can get.

  In the above embodiment, as shown in FIG. 5, the polymer material coating layers 150 and 150 are formed as the pressure cushion layers on the pressure surfaces of the metal main body portions 51a and 52a of the pressure members 51 and 52. 12, the polymer material sheets 151 and 151 forming the pressure cushion layer may be detachably disposed between the temporary support laminate 130 ′ and the pressure members 51 and 52. Further, when the warp of the temporary support laminate 130 ′ is small, as shown in FIG. 13, one or both of the polymer material coating layer and the polymer material sheet can be omitted. FIG. 13 is an example in which both the polymer material coating layer and the polymer material sheet are omitted, and only the polymer material bonding layer 111 for bonding the temporary support substrate 110 is provided as a pressure cushion layer.

  In addition, as shown in FIG. 14, the light emitting device 100 to be manufactured uses an Au-based metal layer 10 (first Au-based metal layer 10a + second Au-based metal layer 10b) exclusively for bonding, and an Au-based metal layer. A reflective metal layer 10 r different from 10 may be provided between the Au-based metal layer 10 and the compound semiconductor layer 50. As such a reflective metal layer 10r, an Ag-based reflective layer mainly composed of Ag or an Al-based reflective layer mainly composed of Al can be used. In this case, the bonding-side bonded alloyed layer can be composed of an Ag-based material such as AgGeNi in the case of an Ag-based reflective layer, or an Al-based material such as AlGeNi in the case of an Al-based reflective layer. . The manufacturing process is substantially the same except that the bonding alloyed layer 31 is covered with the reflective metal layer 10r and then covered with the first Au-based metal layer 10a.

  Further, the present invention is also applicable to a light emitting element structure in which a transparent conductive substrate made of GaP or the like is bonded to a compound semiconductor layer directly or via a conductive oxide layer such as ITO (Indiumu Tin Oxide) instead of the Si substrate 7. Can be applied.

  Moreover, the light emitting layer part 24 can also be comprised as an active layer and a clad layer having a double hetero structure comprised of InAlGaN or MgZnO.

The schematic diagram which shows an example of the light emitting element used as the application object of this invention. Process explanatory drawing which shows an example of the manufacturing method of the light emitting element of this invention. Process explanatory drawing following FIG. Process explanatory drawing following FIG. The schematic diagram explaining the principal part of a bonding apparatus. The figure explaining an example of a bonding process in detail. The figure which illustrates typically an example of the control pattern of the heating and pressurization in a bonding process. Explanatory drawing which shows typically the effect | action of the pressurization cushion layer in a bonding process. The schematic diagram explaining the principal part of a more preferable bonding apparatus. The schematic diagram explaining a mode that curvature generate | occur | produces in a compound semiconductor layer. The schematic diagram explaining a mode that the curvature of a compound semiconductor layer was reduced by bonding of a temporary support substrate. The schematic diagram explaining the modification of a pressurization cushion layer with the principal part of a bonding apparatus. The schematic diagram which shows the example which abbreviate | omitted the pressurization cushion layer by the side of a pressurization member. The schematic diagram which shows another example of the light emitting element used as the application object of this invention.

Explanation of symbols

1 GaAs single crystal substrate (growth substrate)
7 Si substrate (element substrate)
9 Light extraction side electrode 9a 'AuBe bonding metal layer (light extraction side bonding metal layer)
9a AuBe bonding alloying layer (light extraction side bonding alloying layer)
10 Au-based metal layer (metal layer)
DESCRIPTION OF SYMBOLS 10a 1st Au type metal layer 10b 2nd Au type metal layer 20 Current spreading layer 24 Light emitting layer part 32 AuGeNi joining alloying layer (bonding side joining alloying layer)
50 Compound Semiconductor Layer 51 First Pressure Member 51a Metal Main Body 52 Second Pressure Member 52a Metal Main Body 100 Light Emitting Element 110 Temporary Support Substrate 111 Polymer Material Bonding Layer (Pressure Cushion Layer)
120 Temporary Support Laminated Body 130 Laminated Body 130 ′ Temporary Support Laminated Body 150 Polymer Material Coating Layer (Pressure Cushion Layer)
151 Polymer material sheet (pressure cushion layer)

Claims (12)

A method for manufacturing a light emitting device in which an element substrate is bonded to a compound semiconductor layer made of a III-V group compound semiconductor having a light emitting layer portion,
A laminate in which the compound semiconductor layer and the element substrate are overlapped is created, and between the first pressure member and the second pressure member each having a metal body, the metal body of the first pressure member and A pressure cushion layer made of a thermoplastic polymer material is provided between the first main surface of the laminate and at least one of the metal main body of the second pressure member and the second main surface of the laminate. The laminated body is disposed in an intervening state, and the laminated body is heated between the first pressure member and the second pressure member while heating the laminated body to a bonding temperature at which the pressure cushion layer is softened. A method for manufacturing a light-emitting element, wherein the compound semiconductor layer and the element substrate are bonded together by pressing the laminated body through the softened pressure cushion layer.   The outer diameter of the main surface of the compound semiconductor layer is d (mm), and the displacement in the thickness direction of the warp occurring in the compound semiconductor layer is u (μm). The method for producing a light-emitting element according to claim 1, wherein one having a warpage in a range of 7 (μm / mm) or less is used.   The method of manufacturing a light emitting device according to claim 1, wherein the pressure cushion layer is a polymer material coating layer formed on a surface of the metal body.   The method for manufacturing a light emitting element according to claim 1, wherein the pressure cushion layer is a polymer material sheet that is detachably inserted between the metal body and the laminate. .   The method for manufacturing a light-emitting element according to claim 3 or 4, wherein the polymer material coating layer or the polymer material sheet is made of a fluororesin.   A temporary support substrate is bonded to the first main surface side of the compound semiconductor layer via a polymer material bonding layer forming the pressure cushion layer, and the laminated body is bonded to the first pressure member together with the temporary support substrate. The method for manufacturing a light-emitting element according to claim 1, wherein pressing and heating are performed between the second pressure member and the second pressure member. In the light emitting element, the light extraction surface side electrode is formed so as to cover a part of the first main surface which becomes the light extraction surface of the compound semiconductor layer, while the light emission element is formed on the second main surface of the compound semiconductor layer. The element substrate is bonded through a metal layer having a reflection surface that reflects light from the layer portion to the light extraction surface side, and the stacked body includes the element substrate, the metal layer, and the compound. A semiconductor layer is laminated in this order, and a bonded-side bonded alloyed layer for reducing contact resistance between the compound semiconductor layer and the metal layer is provided between the metal layer and the compound semiconductor layer. Formed as an arrangement,
A compound semiconductor layer growth step of epitaxially growing the compound semiconductor layer on the first main surface of the growth substrate;
A light extraction surface side electrode forming step of forming the light extraction surface side electrode on the first main surface side of the compound semiconductor layer;
With the growth substrate attached to the second main surface side of the compound semiconductor layer, the first main surface of the compound semiconductor layer on which the light extraction surface side electrode is formed is interposed via the polymer material bonding layer. Bonding the temporary support substrate, and then removing the growth substrate to form a temporary support bonded body forming the temporary support bonded body in which the compound semiconductor layer and the temporary support substrate are bonded together When,
A bonding side bonding metal layer forming step of forming a bonding side bonding metal layer on the second main surface of the compound semiconductor layer exposed by removing the growth substrate;
Bonding side alloying in which the bonding side alloying heat treatment is performed in the state of the temporary support bonded body by alloying the bonding side bonding metal layer with the compound semiconductor layer to form the bonding side bonding alloyed layer. A heat treatment step;
After the bonding-side alloying heat treatment is completed, the bonding temperature is set lower than the bonding-side alloying heat-treating step, and the bonding process is performed, so that a metal is formed on the second main surface of the compound semiconductor layer. An element substrate bonding step of creating an element substrate bonded body in which the element substrates are bonded through the layers;
The method for manufacturing a light-emitting element according to claim 6, wherein a temporary support substrate separation step of separating the temporary support substrate from the element substrate bonded body is performed in this order.   In order to reduce the contact resistance between the light extraction surface side electrode and the compound semiconductor layer, the light extraction surface side electrode itself or a light extraction surface disposed between the light extraction surface side electrode and the compound semiconductor layer 8. The method for manufacturing a light-emitting element according to claim 7, wherein a light extraction side alloying heat treatment for alloying a side bonding metal layer and the compound semiconductor layer is performed before the element substrate bonding step.   9. The light-emitting element according to claim 6, wherein after the polymer material bonding layer is heated and softened, the pressure increase of the bonding pressure to the laminate is started. Manufacturing method. A Si substrate is used as the element substrate, and a first Au-based metal layer to be a part of the metal layer is formed on the second main surface of the compound semiconductor layer, and on the other hand, the Si substrate is bonded to the bonding surface. Forming a second Au-based metal layer to be a part of the metal layer, bonding the first Au-based metal layer and the second Au-based metal layer by bonding,
Forming a Si diffusion preventing layer between the Si substrate and the second Au-based metal layer to prevent Si components from the Si substrate from diffusing into the second Au-based metal layer;
Either the polymer material coating layer or the polymer material sheet and the polymer material binding layer are used in combination as the pressure cushion layer, and the polymer material coating layer or the high material layer is used as the polymer material binding layer. Adopting a softening temperature lower than the thermoplastic polymer material that forms the molecular material sheet,
The laminated body is heated to an intermediate temperature that is equal to or lower than the bonding temperature and the polymer material bonding layer is softened, and after the intermediate temperature is reached, pressure increase of the bonding pressure to the laminated body is started, The method for manufacturing a light-emitting element according to claim 7, wherein the temperature of the stacked body is increased from the intermediate temperature toward the bonding temperature after the start of pressure increase.   The method for manufacturing a light-emitting element according to claim 10, wherein the pressurization of the bonding pressure to the stacked body is started in a state where the stacked body is held at the intermediate temperature.   The bonding is performed by setting the pressure for bonding pressure to 5 kPa to 1000 kPa, the bonding temperature to 200 ° C. to 280 ° C., and the holding time at the set pressure to 10 minutes to 60 minutes. The method for manufacturing a light-emitting element according to claim 10 or 11, wherein:

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