JP2005109207A - Light emitting element and method of manufacturing the same - 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 through metallic layers, by suppressing the cracking of the compound semiconductor layer, particularly, the formation of cracks in the circumference of a junction alloy layer formed in the jointing interfaces of the compound semiconductor layer with the metallic layers, even when the compound semiconductor layer is thin and warped, or the like. <P>SOLUTION: The junction alloy layer 31 is formed on the second principal surface of the compound semiconductor layer 50 in a state where part of the layer 31 further cuts into the semiconductor layer 50 side than the second principal surface, and the remaining part of the layer 31 is protruded from the second principal surface. A laminate 130' is produced on the second principal surface of the semiconductor layer 50 having the alloyed jointing layer 31 by laminating the metallic layers 10a and 10b and element substrate 7 upon another, and the compound semiconductor layer 50 is stuck to the element substrate 7 through the metallic layers 10a and 10b by sticking the laminate 130' to the semiconductor layer 50 and heating the laminate 130' to a sticking temperature. The laminate 130' is pressed against the layer 50. Then the pressing for sticking is started at a temperature lower than the sticking temperature, and the temperature rise of the laminate 130' from the pressing starting temperature to the sticking temperature is started at timing delayed from the pressing timing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

JP 2001-339100 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.

  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. Such cracks and chips are of course also a problem of macro cracks that can be visually confirmed in the state of a bonded wafer in which a large number of light emitting element chips are collectively formed. The occurrence of micro cracks is also serious.

  In order to reduce the contact resistance between the metal layer and the light emitting layer portion, it is necessary to dispose a bonding alloyed layer. This bonding alloyed layer is formed by dispersing a bonding metal layer made of an AuGeNi alloy or the like on the bonding surface of the metal layer to the light emitting layer portion, and then alloying with the compound semiconductor forming the light emitting layer portion by heat treatment. Alloyed layer. Then, the main surface of the light emitting layer part is covered with a metal layer together with the bonding alloying layer, and is bonded to the element substrate by applying pressure and heating to form a light emitting layer part region surrounding the bonding alloying layer. Many microcracks may occur. Such micro cracks are formed starting from a bonded alloying layer that forms a conduction path during light emission driving, and thus may increase contact resistance and current leakage. In addition, current is concentrated during energization and crack propagation is likely to proceed, current leakage gradually becomes more prominent, and light emission intensity is likely to deteriorate over time. 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-described defects tend to be more likely to occur due to such warpage. In addition, when the thermal stress is generated due to the temperature distribution in the light emitting layer at the time of bonding, the defect tends to be promoted.

  The problem of the present invention is that even when the compound semiconductor layer including the light emitting layer portion is thin and warps, the compound semiconductor layer is cracked, in particular, a bonded alloy formed at the bonding interface with the metal layer. A method for manufacturing a light-emitting element capable of surely bonding the element substrate and the compound semiconductor layer through the metal layer while suppressing the formation of cracks around the insulating layer, and can be realized only by the manufacturing method of the present invention A light emitting device having a structure in which an element substrate and a compound semiconductor layer are bonded via a metal layer, and reducing contact formation by reducing the formation of cracks in the compound semiconductor layer around the bonded alloyed layer. An object of the present invention is to provide a light emitting element having low resistance and capable of maintaining good light emission intensity over a long period of time.

Means for Solving the Problems and Effects of the Invention

The method for producing a light emitting element of the present invention is for producing a light emitting element in which an element substrate is bonded to a compound semiconductor layer having a light emitting layer part via a metal layer,
A laminated body in which a metal layer and an element substrate are superimposed on the second main surface of the compound semiconductor layer is created, and the laminated body is bonded and pressed between the first pressure member and the second pressure member. By heating to the bonding temperature, the compound semiconductor layer and the element substrate are bonded via the metal layer,
While starting the laminating pressurization at a temperature lower than the laminating temperature, the temperature rise of the laminate from the temperature at the start of pressurization until reaching the laminating temperature is delayed at a timing later than the start of the pressurization. It is characterized by starting.

  When a compound semiconductor layer is bonded to an element substrate via a metal layer, if the temperature distribution is not stabilized at the time of raising the temperature to the bonding temperature, the pressure is rapidly increased to the set pressure of the bonding. In some cases, the brittle compound semiconductor layer is cracked or cracked. The metal layer intervening for bonding tends to cause plastic flow when pressurized in a heated state, but if the pressure is increased excessively rapidly, the plastic flow cannot fully follow the pressure rise, and the applied pressure is increased. It becomes easy to invite non-uniformity. Such non-uniformity of the applied pressure becomes more significant when the compound semiconductor layer is warped. And the effect of non-uniform temperature distribution of the laminate (for example, generation of thermal stress distribution) that occurs when the temperature rises to the bonding temperature overlaps with this, which promotes cracks in the compound semiconductor layer it is conceivable that.

  Further, prior to bonding, when the metal layers are distributed and arranged on the compound semiconductor layer side and the element substrate side, and the metal layer on the compound semiconductor layer side and the metal layer on the element substrate side are bonded together, Due to various factors accompanying heating (particularly heating in the atmosphere), the bonded surfaces of both metal layers may be oxidized or altered. However, when the above method is adopted, after the two metal layers are stacked and press-contacted, the temperature rise from the temperature at the start of pressurization to the final bonding temperature is started. The effect of the oxidation and alteration of the bonding surface can be reduced, and a strong bonding state can be easily obtained.

  The temperature of the laminate at the start of pressurization may be room temperature (for example, around 20 ° C.), or may be set to a temperature higher than room temperature as long as the effects of the present invention are not impaired.

The first of the more concrete methods is to disperse and form a bonding metal layer containing an alloy component that reduces contact resistance with the compound semiconductor layer on the second main surface of the compound semiconductor layer, and then heat-treat with the alloy. The joining alloyed layer in which the joining metal layer and the compound semiconductor layer are alloyed is formed in such a manner that a part of the joining alloying layer bites into the compound semiconductor layer side of the second main surface and the remaining part protrudes from the second main surface. And
A laminated body in which a metal layer and an element substrate are superposed on the second main surface of the compound semiconductor layer on which the bonded alloying layer is formed is formed, and bonding pressure is applied to the laminated body at a constant set pressure. ,
The gist is to resume the pressure increase after maintaining the intermediate pressure by interrupting the pressure increase at an intermediate pressure lower than the set pressure during the pressure increase toward the set pressure.

  As a result of investigation by the present inventor, when the temperature distribution is not stabilized at the time of raising the temperature to the bonding temperature and the pressure is rapidly increased toward the set pressure of the bonding, the compound semiconductor layer, in particular, the bonded alloyed layer. It was found that microcracks are likely to occur around That is, the influence of non-uniform pressure (and warping of the compound semiconductor layer) due to the delay of plastic flow of the metal layer when the pressure is excessively rapid overlaps with the non-uniform temperature distribution of the laminate. It is considered that the generation of microcracks in the brittle compound semiconductor is more facilitated around the bonded alloyed layer where the load is likely to concentrate.

  Therefore, in the above method, when the intermediate pressure lower than the final set pressure is reached after the start of the pressure increase, the pressure increase is temporarily stopped there and the intermediate pressure is held for a predetermined time. In other words, it is possible to gain time by stabilizing the temperature distribution of the laminate by artificially delaying the pressure increase to the set pressure by maintaining the intermediate pressure. Generation | occurrence | production etc. can be suppressed. As a result, not only macro cracks that can be visually confirmed, but also microcrack generation in the compound semiconductor layer around the bonded alloyed layer can be effectively suppressed.

  In this case, it is further preferable that the temperature rise toward the bonding temperature of the laminate is continued while maintaining the intermediate pressure. In other words, by holding the intermediate pressure intentionally, the pressure increase to the set pressure is artificially delayed, and in the meantime, by raising the temperature to the bonding temperature in advance, in a state of suppressing the unfavorable stress generation due to the uneven temperature distribution, Pressurization to the final set pressure can be continued. As a result, it is possible to effectively suppress the generation of cracks in the compound semiconductor layer and to increase the efficiency of pressure increase.

The second specific method is that the light emitting element has a light emitting layer portion made of AlGaInP or InAlGaN, the metal layer has an Au-based metal layer mainly composed of Au, and the element substrate is a Si substrate.
A bonding metal layer containing a contact alloy component for reducing contact resistance with the compound semiconductor layer is dispersedly formed on the second main surface of the compound semiconductor layer, and alloying heat treatment is performed, whereby the bonding metal layer and the compound semiconductor are formed. A bonded alloyed layer formed by alloying with the layer, a part of which bites into the compound semiconductor layer side of the second main surface, and the remaining part protrudes from the second main surface;
A first Au-based metal layer mainly composed of Au to be a part of the metal layer is formed on the second main surface of the compound semiconductor layer on which the bonding alloying layer is formed. A second Au-based metal layer mainly composed of Au to be a part of the metal layer is formed, and a first Au-based metal layer and a second Au-based metal layer are overlapped to form a stacked body. By bonding and pressing the body between the first pressure member and the second pressure member to the bonding temperature, the first Au-based metal layer and the second Au-based metal layer are bonded together. And combine
Forming a Si diffusion prevention layer between the Si substrate and the second Au-based metal layer to prevent the Si component from the Si substrate from diffusing into the second Au-based metal layer;
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 setting pressure to 10 minutes to 60 minutes. .

  In the above method, a Si substrate is used as an element substrate of a light emitting element to be applied. 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 the case of a thin compound semiconductor layer made of AlGaInP or InAlGaN, warping is very often caused by a mismatch in lattice constant with a growth substrate, a difference in linear expansion coefficient, or the like. In consideration of bonding such a compound semiconductor layer to an Si substrate through an Au-based metal layer, the setting pressure of the bonding pressure is 5 kPa or more and 1000 kPa or less, and the bonding temperature is 200 ° C. or more and 280. It is desirable to perform bonding by setting the holding time at 10 ° C. or lower and the set pressure at 10 to 60 minutes. In order to increase the adhesion between Au-based metal layers formed on the compound semiconductor layer side and the Si substrate side, the above-mentioned cracks and cracks (particularly, microcracks around the bonded alloyed layer) do not occur in the compound semiconductor layer. Set the bonding pressure as high as possible in the range, promote plastic fluid follow-up deformation between soft Au-based metal layers, and cause mutual diffusion while evenly adhering Au-based metal layers against warping However, it is important for obtaining a uniform and strong bonded state.

  Specifically, when the set pressure is less than the above lower limit value, the adhesion between the Au-based metal layers does not sufficiently proceed due to insufficient pressure, making it difficult to obtain a uniform bonded state. Further, when the bonding temperature is less than the above lower limit value, the interdiffusion rate between the Au-based metal layers for forming the bonding state decreases, and it becomes difficult to obtain a uniform bonding state. In addition, if the holding time is less than 10 minutes, it becomes difficult to cause the interdiffusion between Au-based metal layers to progress uniformly over the entire bonding surface, and as a result, a uniform bonding state cannot be obtained. On the other hand, when the set pressure exceeds the upper limit, cracks and cracks (particularly, the aforementioned microcracks) are likely to occur in the thin compound semiconductor layer. In addition, when the bonding temperature exceeds the upper limit, Si diffusion from the Si substrate to the Au-based metal layer is likely to proceed, causing problems such as a decrease in reflectivity due to boiling to the reflecting surface formed by the metal layer. It becomes easy. Furthermore, it is undesirable for the holding time to exceed 60 minutes in view of the efficiency of the bonding process, and there is an increased concern that the reflectivity will decrease due to Si diffusion from the Si substrate.

  Since plastic fluid follow-up deformation between Au-based metal layers during pressurization takes time, if the pressure increase rate to the set pressure is set too large, the deformation of the Au-based metal layer against the warpage is increased. Thus, cracks and cracks in the compound semiconductor layer, in particular, microcracks around the bonded alloyed layer that tends to concentrate the load are likely to occur. In this case, if the pressure increase rate at the time of pressure increase to the set pressure is suppressed to 100 kPa / min or less, the above-described problem can be effectively prevented. In addition, since excessively reducing the pressure increase rate also leads to a reduction in the efficiency of the bonding process, it is desirable to set the pressure increase rate to, for example, 1 kPa / min or more.

  The second of the above specific methods is combined with the first of the above specific methods, that is, the bonding pressure is started at a temperature lower than the bonding temperature, while the bonding temperature is determined from the temperature at the start of the pressing. It is possible to combine a method of starting the temperature rise of the laminated body until reaching the point of time at a timing delayed from the start of pressurization, which contributes to prevention of cracks in the compound semiconductor layer.

By employing the method of the present invention, the following light emitting device of the present invention can be realized. That is, in the light emitting device of the present invention, the device substrate is bonded to the compound semiconductor layer having the light emitting layer portion made of AlGaInP or InAlGaN through the metal layer having the Au-based metal layer mainly composed of Au,
A bonded alloyed layer obtained by alloying a bonded metal layer containing an alloy component that reduces contact resistance with the compound semiconductor layer with the compound semiconductor layer at the bonded interface between the metal layer and the compound semiconductor layer is formed into the bonded alloy. A part of the layer bites into the compound semiconductor layer side, and the remaining part bites into the metal layer so as to be dispersed and formed at the bonding interface.
In addition, the total number of the bonded alloyed layers formed in a dispersed manner is N, and the number of the individual bonded alloyed layers that have cracks in the compound semiconductor layer in contact with the bonded alloyed layer is N1. N1 / N is 0.05 or less.

  The light-emitting device of the present invention can be manufactured by the above-described manufacturing method of the present invention, and as a result of effectively preventing the occurrence of microcracks around the bonded alloyed layer that tends to concentrate the load at the time of bonding, a plurality of dispersions are formed. Of the bonded alloyed layers, the number ratio of those having cracks can be 0.05 or less (that is, 5% or less). As a result, contact resistance between the bonded alloying layer and the compound semiconductor layer is less likely to increase and current leakage occurs, and crack propagation due to current concentration during energization, and thus degradation over time in light emission intensity, is unlikely to occur and is high over a long period of time. Luminous performance can be maintained.

  Next, in the method for producing a light-emitting element of the present invention, a temporary support substrate is bonded to the first main surface side of the compound semiconductor layer via a bonding layer, and a metal layer is further formed on the second main surface of the compound semiconductor layer. The laminated body on which the element substrate is overlaid can be sandwiched and heated between the first pressure member and the second pressure member together with the temporary support substrate. Since the temporary support substrate is bonded to the thin compound semiconductor layer, handling of the compound semiconductor layer when forming the stacked body becomes extremely easy. 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 this case, if the bonding layer is composed of a polymer material bonding layer, after the compound semiconductor layer is bonded to the element substrate, the polymer material bonding layer is softened by heating or dissolved in an organic solvent to provide temporary support. The substrate can be easily separated from the compound semiconductor layer.

  When the polymer material bonding layer is composed of a thermosetting polymer material, particularly an epoxy resin or a urethane resin, it is possible to effectively suppress gas generation from the polymer material bonding layer during the bonding heat treatment, and a compound due to a gas component. It is possible to more effectively prevent contamination of the semiconductor layer (particularly contamination by carbon) and cracking of the compound semiconductor layer due to rapid gas generation.

  Further, in the method for manufacturing a light-emitting element of the present invention, a laminate in which a compound semiconductor layer and an element substrate are overlapped is created, and a first pressurizing member and a second pressurizing member each having a metal main body are formed. And at least one between the metal main body of the first pressure member and the first main surface of the laminate and between the metal main body of the second pressure member and the second main surface of the laminate. The first pressurizing member and the second pressurizing member are disposed while the laminated body is disposed in a state where a pressure cushion layer made of a molecular material is interposed, and the laminate is heated to a bonding temperature at which the pressure cushion layer is softened. The compound semiconductor layer and the element substrate can be bonded together by pressing the laminated body through a softened pressure cushion layer.

  As already explained, 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. Such non-uniform bonding pressure is promoted by non-uniform thickness and warpage generated in the element substrate and the compound semiconductor layer. Among these, 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, 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 a bonding temperature at which the thermoplastic polymer material is softened is set. 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, cracks (including the above-mentioned microcracks) and chipping due to the effects of uneven thickness and warping are extremely effectively prevented or suppressed. can do.

  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 made of a thermoplastic polymer material forming a pressure cushion layer, and the laminate is bonded together with the temporary support substrate. It is also possible to heat to the bonding temperature while applying pressure between the one pressure member and the second pressure 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 There is also an advantage that handling is extremely easy.

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;
In the state where the growth substrate is 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 via the bonding layer, and then 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 the growth substrate;
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 via a 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 heat history of the alloying heat treatment is not added to the bonding metal layer in contact with the bonding side bonding metal layer, and the component of the bonding side bonding metal layer (particularly, the alloy component for contact) is reduced. The problem of diffusing in the metal layer surface and reducing the reflectivity can be effectively prevented.

  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 particular, when the second manufacturing method of the present invention is adopted, the bonding temperature is 200 ° C. or higher and 280 ° C. or lower, which is much lower than the alloying heat treatment temperature. Therefore, although the holding time at the set pressure and the bonding temperature is as long as 10 minutes or more, the bonding metal layer component (particularly, the alloy component for reducing contact resistance) diffuses in the metal layer surface. Can be effectively suppressed.

  Next, 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.

  When a Si substrate is used as the element substrate, 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, while a part of the metal layer is formed on the bonding surface of the Si substrate. A second Au-based metal layer to be formed can be formed, and the first Au-based metal layer and the second Au-based metal layer can be bonded together. 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.

  Even when a pressure cushion layer is provided, the set pressure for 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 also desirable to perform bonding. When the set pressure is less than the lower limit, even if the pressure cushion layer is softened to some extent, the follow-up deformation does not proceed sufficiently due to insufficient pressure, making it difficult to obtain a uniform bonded state. In addition, when the bonding temperature is less than the above lower limit value, the interdiffusion rate between the Au-based metal layers for forming the bonding state is lowered, and the pressure cushion layer is apt to be insufficiently softened, and is uniform. It is difficult to obtain a proper bonding state. In addition, when the holding time is less than 10 minutes, the mutual diffusion between the Au-based metal layers is made uniform over the entire bonding surface in combination with the fact that the flow for the follow-up deformation of the pressure cushion layer tends to be insufficient. It becomes difficult to advance, and as a result, a uniform bonding 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. Furthermore, it is undesirable for the holding time to exceed 60 minutes in view of the efficiency of the bonding process, and there is an increased concern that the reflectivity will decrease due to Si diffusion from the Si substrate.

  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 element 100 includes an Au-based metal layer 10 as a metal layer on a first main surface of a silicon 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, the main surfaces of the layers and the substrate, as shown in FIG. 1, are defined as a state where the light extraction surface PF of the light emitting element 100 is on the upper side, and a surface appearing on the upper side of the drawing in the normal state is a 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. It is also possible to configure the entire light extraction surface side electrode 9 with an AuBe alloy and omit the bonding alloyed layer 9a. 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).

  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 15 μm or less).

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

  Between the light emitting layer portion 24 and the Au-based metal layer 10 (first Au-based metal layer 10a), an AuGeNi bonding alloyed layer 31 (for example, Ge: 15% by mass, Ni: 10) as a bonding-side bonding alloyed layer. % By mass), which 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 Au-based metal layer 10. The bonding alloyed layer 31 partially bites into the compound semiconductor layer 50 side at the bonding interface between the Au-based metal layer 10 and the compound semiconductor layer 50, and the remaining portion bites into the Au-based metal layer 10.

  Further, in the conventional light emitting device, as shown in FIG. 16, the microcrack MC to the brittle compound semiconductor layer 50 is formed around the bonding alloyed layer 31 where load is likely to concentrate in the bonding process described later. Tended to occur in large numbers. However, by employing the manufacturing process unique to the present invention described later, the formation of the microcracks MC as described above is suppressed as shown in FIG. Specifically, the total number of bonded alloyed layers 31 formed in a dispersed manner is N, and among the individual bonded alloyed layers 31, cracks are generated in the compound semiconductor layer 50 in contact with the bonded alloyed layer 31 in the periphery thereof. N1 / N is 0.05 or less (that is, 5% or less, preferably 1% or less), where N1 is the number of objects.

  Returning to FIG. 1, an AuSb bonding alloyed layer 32 (for example, Sb: 2% by mass) is interposed between the silicon 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. Further, in the present embodiment, the entire surface of the AuSb bonding metal layer 32 is a diffusion blocking layer that prevents the Si component from the silicon substrate 7 from diffusing into the Au-based metal layer 10 during the bonding heat treatment described later (specifically, Is a Ti layer). The thickness of the diffusion blocking layer 10c is 1 nm or more and 10 μm or less (200 nm in this embodiment). The diffusion blocking layer may be composed of a Ni layer or a Cr layer instead of the Ti layer. Further, 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 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 alloying heat treatment when forming the AuGeNi bonding alloyed layer 31 on the side.

  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, a silicon substrate, a ceramic plate (for example, an alumina plate), or a metal plate can be used. 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 formation area ratio of the AuGeNi bonding metal layer with respect to the entire area of the second main surface of the compound semiconductor layer 50 is 1% or more and 25% or less.

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 silicon substrate 7, forming AuSb bonding metal layers on both main surfaces, 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, a diffusion blocking layer 10c is formed that prevents the components of the silicon substrate 7 from diffusing into the second Au-based metal layer 10b in the subsequent element substrate bonding step. 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.

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 silicon 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 silicon substrate 7 are overlapped. The compound semiconductor layer 50 is overlapped with the silicon substrate 7 that 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. This functions as a pressure transmission medium that uniformly transmits the applied pressure from the temporary support substrate 110 side in the surface, and is effective in preventing cracks in the compound semiconductor layer 50 and microcracks MC as shown in FIG. Demonstrate. In particular, when the compound semiconductor layer 50 is warped and deformed, the restraint against deformation of the compound semiconductor layer 50 is weakened by increasing the fluidity of the polymer material bonding layer 111, so that the effect of preventing cracks and microcracks can be prevented. Becomes even more prominent. 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.

  In order to increase the adhesion between the Au-based metal layers 10a and 10b formed on the compound semiconductor layer 50 side and the Si substrate 7 side, respectively, the plasticity between the soft Au-based metal layers 10a and 10b is increased by pressurization at a high temperature. In order to obtain a uniform and strong bonding state, it is important to promote fluid follow-up deformation and to cause mutual diffusion while evenly adhering the Au-based metal layers 10a and 10b against warping. . Since it takes time to follow and deform between the plastic fluid Au-based metal layers 10a and 10b during pressurization, if the pressure increase rate to the set pressure is set too large, the Au-based metal layer 10a resists warping. , 10b can no longer follow the pressure increase, and cracks and cracks in the compound semiconductor layer 50, in particular, microcracks around the bonded alloyed layer 31 where the load tends to concentrate as shown in FIG. In addition, since the flow of the polymer material bonding layer 111 during pressurization is accompanied by a certain delay, if the pressurization speed during pressurization is set excessively large, a high height that matches the shape of the compound semiconductor layer 50 is obtained. The deformation of the molecular material bonding layer 111 cannot follow the pressure increase, and the generation of cracks and microcracks in the compound semiconductor layer 50 is promoted. 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 does not proceed so rapidly (the effect of suppressing Si diffusion from the Si substrate 7 by the Si diffusion element layer 10c is great) and the polymer material coating layer 150 forming the pressure cushion layer is softened. Is set to 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 applied to the bonding interface of the Au-based metal layers 10a and 10b, which is effective in preventing cracks and microcracks.

  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 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 10a. The bonding surface (first main surface) 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. 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. As a result, the occurrence of microcracks in the compound semiconductor layer 50 around the bonded alloyed layer 31 as well as macro cracks that can be visually confirmed can be more effectively suppressed.

  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. Generation of cracks and mirocracks can be effectively prevented. However, as shown by the one-dot chain line in FIG. 7, the intermediate pressure holding is omitted, and the intermediate pressure holding period is absorbed, so that the pressure increase rate in the preceding and following periods is reduced, and at a constant speed of 100 kPa / min or less. It is also possible to continuously increase the pressure to the set pressure P3.

  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. Thereby, even if some warp is generated in the compound semiconductor layer 50 between the first Au-based metal layer 10a and the second Au-based metal layer 10b, the entire surface without causing cracks or microcracks. An extremely uniform 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 made to adhere and can effectively prevent the influence of Si diffusion on the bonding interface between the two. In addition, the Si diffusion element layer 10c has a great effect that the Si diffusion itself from the Si substrate 7 to the second Au-based metal layer 10b is suppressed. Then, after pressurization is started 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 and microcracks in the compound semiconductor layer 50. The temporary support laminate 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 the above-described alloy component diffusivity for the contact can be kept below 30%. Highly reflective surface 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 made of an organic solvent such as toluene or a ketone solvent (for example, methyl ethyl ketone (MEK)). Dissolve and remove.

  Alternatively, the temporary support substrate 110 may be separated by immersing the temporary support substrate 110 in an organic solvent while being bonded to the compound semiconductor layer 50 to dissolve the polymer material bonding layer 111. Further, the polymer material bonding layer 111 may employ an epoxy resin or a urethane resin instead of the thermoplastic resin. Thereby, gas generation from the polymer material bonding layer 111 during the bonding heating can be more effectively suppressed. In addition, when using an epoxy resin, you may employ | adopt either an amine curable type and a polyamide curable type. In the case where the polymer material bonding layer 111 is composed of a thermosetting resin, the polymer material bonding layer 111 itself cannot be used as a pressure cushion layer because it cannot be softened at the time of bonding and heating. In this case, it is effective to use the polymer material coating layer 150 made of the aforementioned thermoplastic resin or the polymer material sheet made of the thermoplastic resin as the pressure cushion layer.

  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 provisional support layer 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 contact metal portion 32 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 applied 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 (Indium 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. The top view which shows typically an example of the dispersion | distribution formation form of the bonding side joining alloying layer. The top view which shows a mode that a microcrack is formed in a compound semiconductor layer around the bonding side joining alloying layer.

Explanation of symbols

1 GaAs single crystal substrate (growth substrate)
7 Silicon 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 31 AuGeNi joining alloying layer (bonding side joining alloying layer)
31d Diffusion region 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)
MC micro crack

Claims (17)

A method for manufacturing a light emitting device in which an element substrate is bonded to a compound semiconductor layer having a light emitting layer portion via a metal layer,
A laminated body in which the metal layer and the element substrate are overlaid on the second main surface of the compound semiconductor layer is created, and the laminated body is bonded between the first pressure member and the second pressure member. Bonding the compound semiconductor layer and the element substrate through the metal layer by heating to the bonding temperature while applying pressure,
While the laminating pressure is started at a temperature lower than the laminating temperature, the temperature rise of the laminate from the temperature at the start of pressurization until the laminating temperature is reached, A method for manufacturing a light emitting element, characterized by starting at a delayed timing. A bonding metal layer containing an alloy component that reduces contact resistance with the compound semiconductor layer is dispersedly formed on the second main surface of the compound semiconductor layer and subjected to an alloying heat treatment to thereby form the bonding metal layer and the compound semiconductor. A bonded alloyed layer formed by alloying with the layer is formed in a form in which a part bites into the compound semiconductor layer side with respect to the second main surface and a remaining part protrudes from the second main surface;
A laminated body in which the metal layer and the element substrate are superimposed on the second main surface of the compound semiconductor layer on which the bonding alloyed layer is formed is formed, and the bonding pressure applied to the laminated body is set to a constant value. With pressure,
2. The pressure increase is resumed after maintaining the intermediate pressure by interrupting the pressure increase at an intermediate pressure lower than the set pressure in the course of the pressure increase toward the set pressure. Manufacturing method of light emitting element.   The method for manufacturing a light-emitting element according to claim 2, wherein the temperature rise toward the bonding temperature of the laminated body is continued during the holding at the intermediate pressure. In the light emitting element, the light emitting layer portion is made of AlGaInP or InAlGaN, the metal layer has an Au-based metal layer mainly composed of Au, and the element substrate is a Si substrate.
A bonding metal layer containing an alloy component that reduces contact resistance with the compound semiconductor layer is dispersedly formed on the second main surface of the compound semiconductor layer and subjected to an alloying heat treatment to thereby form the bonding metal layer and the compound semiconductor. A bonded alloyed layer formed by alloying with the layer is formed in a form in which a part bites into the compound semiconductor layer side with respect to the second main surface and a remaining part protrudes from the second main surface;
A first Au-based metal layer mainly composed of Au to be a part of the metal layer is formed on the second main surface of the compound semiconductor layer on which the bonding alloying layer is formed, while the Si substrate Forming a second Au-based metal layer mainly composed of Au to be a part of the metal layer on the bonding surface, and superimposing the first Au-based metal layer and the second Au-based metal layer. A laminated body is prepared, and the laminated body is heated between the first pressure member and the second pressure member while being bonded and pressurized to a bonding temperature. Bonding and bonding two Au-based metal layers,
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;
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 1, wherein:   A laminated body in which a temporary support substrate is bonded to the first main surface side of the compound semiconductor layer via a bonding layer, and the metal layer and the element substrate are superimposed on the second main surface of the compound semiconductor layer, 5. The light-emitting element according to claim 1, wherein the first pressure member and the second pressure member are sandwiched and heated together with the temporary support substrate. Method.   The bonding layer is composed of a polymer material bonding layer, and after the compound semiconductor layer is bonded to the element substrate, the polymer material bonding layer is heated and softened or dissolved in an organic solvent, whereby the temporary support substrate is 6. The method for manufacturing a light-emitting element according to claim 5, wherein the light-emitting element is separated from the compound semiconductor layer.   The method for manufacturing a light-emitting element according to claim 6, wherein the polymer material bonding layer is made of an epoxy resin or a urethane resin.   High thermoplasticity between at least one of the metal body of the first pressure member and the first main surface of the laminate and between the metal body of the second pressure member and the second main surface of the laminate. The laminated body is disposed with a pressure cushion layer made of a molecular material interposed, and the laminated body is heated to a bonding temperature at which the pressure cushion layer softens, while the first pressure member and the first pressure member are heated. The laminate is pressed between the two pressure members through the softened pressure cushion layer, and the compound semiconductor layer and the element substrate are bonded to each other through the metal layer. The manufacturing method of the light emitting element of any one of Claim 1 thru | or 7.   9. The method of manufacturing a light emitting device according to claim 8, wherein the pressure cushion layer is a polymer material coating layer formed on a surface of the metal body.   9. The method of manufacturing a light emitting element according to claim 8, 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 9, 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 made of the thermoplastic polymer material forming the pressure cushion layer, and the laminate is attached to the temporary support substrate. The heating is performed to the bonding temperature while the bonding pressure is applied between the first pressure member and the second pressure member. Of manufacturing the light-emitting device. 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 temporary main surface of the compound semiconductor layer on which the light extraction surface side electrode is formed is interposed via the bonding layer. 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 bonding the support substrate and then removing the growth substrate;
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 temporary support substrate separation step of separating the temporary support substrate from the element substrate bonded body is performed in this order, wherein any one of claims 5, 6, 7, and 12 is performed. A method for producing a light-emitting element according to claim 1.   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 14. The method for manufacturing a light emitting element according to claim 13, wherein 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.   The light emitting device according to claim 12, wherein after the polymer material bonding layer is heated and softened, the pressure increase of the bonding pressure to the stacked body 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,
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 15, wherein the temperature of the laminated body is increased from the intermediate temperature toward the bonding temperature after the start of pressure increase. An element substrate is bonded to a compound semiconductor layer having a light emitting layer portion made of AlGaInP or InAlGaN via a metal layer having an Au-based metal layer mainly composed of Au,
A bonded alloyed layer obtained by alloying a bonded metal layer containing an alloy component that reduces contact resistance with the compound semiconductor layer at the bonded interface between the metal layer and the compound semiconductor layer with the compound semiconductor layer, A part of the bonding alloying layer bites into the compound semiconductor layer side, and the remaining part is dispersedly formed at the bonding interface so as to bite into the metal layer,
In addition, the total number of the bonded alloyed layers formed in a dispersed manner is N, and among the individual bonded alloyed layers, the number of the compound semiconductor layers that are in contact with the bonded alloyed layer in the periphery thereof is N1 And N1 / N is 0.05 or less.

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