JP2007142345A - Nitride semiconductor light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride semiconductor light-emitting element having high light-emitting efficiency which can manufacture a vertical element forming a pair of electrodes on the top and bottom of a chip by employing a semiconductor substrate, prevents optical absorption on the substrate while maintaining high heat conductivity and reduces the dislocation density of a nitride semiconductor to be grown thereon. <P>SOLUTION: A first nitride semiconductor layer 2 is formed on the semiconductor substrate 1, a mask 5 having an opening is provided thereon, and a semiconductor stacking section 10 is provided by stacking nitride semiconductor layers so that a second nitride semiconductor layer 6 selectively grown in the lateral direction of the opening on the mask section 5 may be formed and a light-emitting layer 8 may be formed thereon. The mask section 5 is composed of a metal film 3 formed on the first nitride semiconductor layer side, and a dielectric film 4 formed on the metal film 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device such as a light emitting diode (LED) or a laser diode (LD) using a nitride semiconductor. More specifically, the present invention relates to a nitride semiconductor light emitting device that has excellent crystallinity and excellent external quantum efficiency even when a semiconductor substrate that absorbs light in the light emitting layer is used.

  In recent years, nitride semiconductor light emitting devices such as blue light emitting diodes (LEDs) and laser diodes (LDs) using nitride semiconductors have been put into practical use. For example, as shown in FIG. 4A, an LED emitting blue light using a nitride semiconductor is formed on a sapphire substrate 41 from a low-temperature buffer layer 42 made of GaN or the like by MOCVD, and from GaN or the like. An n-type layer 43 and a material whose band gap energy is smaller than that of the n-type layer 43 and defines an emission wavelength, for example, an InGaN-based compound semiconductor (which means that the ratio of In and Ga can be changed variously, the same applies hereinafter). An active layer (light emitting layer) 44 and a p-type layer 45 made of GaN or the like are laminated to form a semiconductor laminated portion 46, and a p-side electrode 48 is provided on the surface of the semiconductor laminated portion 46 via a translucent conductive layer 47. The n-side electrode 49 is formed on the surface of the n-type layer 43 exposed by etching a part of the laminated semiconductor laminated portion 46 (for example, a special feature) References 1).

  However, the sapphire substrate 41 is an insulating substrate, and electrodes cannot be directly formed on the substrate, and a mesa structure must be formed by performing a process such as etching on a part of the semiconductor stacked portion 46 as described above. Further, the sapphire substrate 41 is used as a conductive substrate for GaAs, GaP, Si, etc., which is conventionally used as a conductive substrate for red and infrared semiconductor light emitting devices, and as a conductive substrate for blue semiconductor light emitting devices. Thermal conductivity is poor compared to SiC substrates. Therefore, a structure in which a nitride semiconductor light emitting element is formed using these semiconductor substrates instead of the sapphire substrate is conceivable.

Specifically, as shown in FIG. 4B, for example, on a Si substrate 61, a buffer layer 62 made of an AlGaN compound or the like by an MOCVD method, an n-type layer 63 made of GaN or the like, and an InGaN compound semiconductor. An active layer (light-emitting layer) 64 made of GaN and a p-type layer 65 made of GaN or the like are laminated to form a semiconductor laminated portion 66, and a p-side electrode 68 is formed on the surface of the p-type electrode 68 via a translucent conductive layer 67. The n-side electrode 69 is provided directly on the back surface of the Si substrate 61. Note that the n-type layer and the p-type layer improve the carrier confinement effect, and therefore further increase the band gap energy such as an AlGaN-based compound (meaning that the ratio of Al and Ga can be variously changed, the same applies hereinafter) on the active layer side. A large semiconductor layer may be used.
Japanese Patent Laid-Open No. 10-173222 (see FIG. 1)

  As described above, by forming a nitride semiconductor light-emitting element directly on a substrate made of GaAs, GaP, Si, SiC, or the like instead of sapphire, a vertical element that forms a pair of electrodes above and below the chip is manufactured. In addition, since the thermal conductivity is larger than that of the sapphire substrate, it is possible to improve the light emission efficiency under high temperature and high output.

  However, the emission wavelength of the nitride semiconductor light emitting device is in the yellow to ultraviolet region, and when the light generated in the light emitting layer of the semiconductor stacked portion propagates in the direction of the substrate and reaches the substrate, when the above-described substrate is used, There is a problem in that light absorption occurs in the substrate, and a light-emitting element with excellent light extraction efficiency cannot be formed. In addition, even when these substrates are used, there is a problem that the difference in lattice constant from the nitride semiconductor layer laminated thereon is large, the dislocation density of the nitride semiconductor layer on the substrate is large, and the light emission efficiency cannot be improved. is there.

  On the other hand, for example, it is conceivable to prevent light absorption by the substrate by evaporating a metal such as W on a Si substrate to form a silicide substrate. However, even in such a case, the reflectance at the silicide portion is not so high, light is transmitted to the substrate side, and eventually light absorption occurs at the substrate, so that the light extraction efficiency cannot be increased. Further, even when a silicide substrate using W is grown by MOCVD, it reacts with ammonia gas, which is a raw material of the GaN-based compound laminated thereon, and an impurity layer is formed at the interface between the silicide and the AlGaN-based compound layer, There is also a problem that the crystallinity of the light emitting layer laminated thereon deteriorates and the light emission efficiency decreases.

  The present invention has been made to solve such a problem, and by using a semiconductor substrate, a vertical element that forms a pair of electrodes on the top and bottom of a chip can be manufactured, and high thermal conductivity can be maintained. However, an object of the present invention is to provide a nitride semiconductor light emitting device having high luminous efficiency by preventing light absorption by the substrate and reducing the dislocation density of the nitride semiconductor grown thereon.

  A nitride semiconductor light emitting device according to the present invention includes a semiconductor substrate, a first nitride semiconductor layer provided on the semiconductor substrate, and a mask portion provided on the first nitride semiconductor layer and having an opening. A second nitride semiconductor layer selectively grown laterally from the opening on the mask portion, and a nitride semiconductor layer stacked on the second nitride semiconductor layer to form a light emitting layer. The mask portion is composed of a metal film provided on the first nitride semiconductor layer side and an insulating film provided on the metal film.

  A nitride semiconductor is a compound in which a group III element Ga and a group V element N or a part or all of a group III element Ga is replaced with another group III element such as Al and In, and / or Alternatively, it refers to a semiconductor made of a compound (nitride) in which a part of N of the group V element is substituted with another group V element such as P or As, and is also referred to as a GaN compound.

  The metal film has at least a two-layer structure of a first metal film provided on the first nitride semiconductor layer side and a second metal film provided on the first metal film, Preferably, the first metal film is made of a metal having a melting point higher than the growth temperature of the semiconductor stacked portion, and the second metal film is made of a metal that reflects light generated in the light emitting layer.

  Specifically, the first metal film is made of at least one of W, Ti and Pd, and the second metal film is made of at least one of Al, Ag and Au. it can.

  According to the nitride semiconductor light emitting device of the present invention, even when a semiconductor substrate that absorbs blue or ultraviolet light, such as GaAs, GaP, SiC, or Si, is used as the substrate, the light is reflected below the insulating film. Since an easy-to-use metal film is formed, this metal film reflects light generated in the light emitting layer, prevents light from reaching the substrate, eliminates light absorption by the substrate, and increases light extraction efficiency. A semiconductor light emitting device that can be obtained is obtained. Further, for increasing the dislocation density resulting from lattice mismatch, a mask having an opening is used, and the second nitride is formed by lateral selective growth using the first nitride semiconductor layer exposed from the opening as a seed. Since the physical semiconductor layer is grown, threading dislocations are blocked by a mask, and a layer having excellent crystallinity with few dislocations can be obtained. As a result, dislocations are reduced in the light emitting layer laminated thereon, the problem of lattice mismatch is solved, and a high quality light emitting layer having a lower dislocation density than that of the prior art can be formed. Further, since the substrate is a semiconductor substrate, a conductive substrate can be formed by doping, and when manufacturing an LED, a mesa structure is not necessary, and a vertical element that forms a pair of electrodes on the top and bottom of a chip is provided. Since it can be manufactured and has a higher thermal conductivity than sapphire, a semiconductor light emitting device with high luminous efficiency can be obtained without thermal saturation to high temperature and high output.

  In addition, by using a metal film having a two-layer structure, the first metal film reflects the light generated in the light emitting layer, and the second metal film uses a metal having a melting point higher than the growth temperature of the semiconductor stacked portion, The metal of the first metal film can be prevented from diffusing into the semiconductor layer, the device characteristics can be prevented from being deteriorated, light absorption at the substrate can be sufficiently prevented, and a semiconductor light emitting device with higher luminous efficiency can be obtained. can get.

  Next, the nitride semiconductor light emitting device of the present invention will be described with reference to the drawings. The nitride semiconductor light-emitting device according to the present invention includes a first nitride semiconductor layer 2 on a semiconductor substrate 1 as shown in a cross-sectional explanatory view of a nitride semiconductor light-emitting device (LED chip) according to an embodiment in FIG. A mask portion 5 having an opening is provided thereon, and a second nitride semiconductor layer 6 and a light emitting layer 8 that are selectively grown laterally from the opening are formed on the mask portion 5. As described above, the semiconductor stacked portion 10 is provided by stacking the nitride semiconductor layers. The mask portion 5 includes a metal film 3 provided on the first nitride semiconductor layer 2 side and a dielectric film 4 provided on the metal film 3. In addition, although the thickness of the substrate is written smaller than the other semiconductor layers in each drawing including FIG. 1, it is actually much larger than each semiconductor layer.

  That is, the present invention uses a metal film 3 that reflects light traveling toward the substrate side, using a semiconductor substrate that is electrically conductive, can form electrodes on the back surface of the substrate, and has high thermal conductivity, The mask portion 5 is formed by the insulating film 4 capable of selective growth. As described above, if a sapphire substrate is used, since it is an insulating substrate, an electrode cannot be formed on the back surface of the substrate, and a mesa structure must be adopted. Also, because the thermal conductivity of the sapphire substrate is poor, High output operation causes thermal saturation and does not increase luminous efficiency. On the other hand, if a conductive substrate such as GaAs, GaP, SiC, or Si is used to prevent this, a conductive substrate can be formed by doping, and there is no need to form a mesa structure. A vertical element that forms a pair of electrodes on the top and bottom can be fabricated, and because of its high thermal conductivity, it is possible to prevent a decrease in light emission efficiency at high temperature operation, but dislocation due to lattice mismatch between the substrate and the nitride semiconductor layer There is a problem that the density is increased and light absorption occurs at the substrate, resulting in a decrease in luminous efficiency.

  However, according to the present invention, for increasing the dislocation density due to lattice mismatch, the mask portion 5 having an opening is used, and the first nitride semiconductor layer 2 exposed from the opening is used as a seed. Since the second nitride semiconductor layer 6 is grown by the lateral selective growth, the mask portion 5 prevents dislocations generated on the substrate side from penetrating into the upper layer. Therefore, the threading dislocation density becomes very small, and a nitride semiconductor layer with high crystallinity can be obtained. Therefore, since a layer with few dislocations can be formed also in the semiconductor laminated portion laminated thereon, the dislocation density is reduced as compared with the conventional case even when a lattice mismatched substrate is used. Further, the problem of light absorption that occurs in the substrate is that the metal film 3 is formed under the insulating film 4, and the metal film 3 reflects the light generated in the light emitting layer 8 and traveling to the substrate 1 side. It is possible to prevent entry into the substrate 1 and avoid light absorption by the substrate 1.

  The semiconductor substrate 1 is an n-type Si substrate in the example shown in FIG. 1, but is not limited to Si, and a semiconductor substrate such as SiC, GaAs, or GaP can be used. In particular, in the present invention, the effect is great when absorbing light emitted from a nitride semiconductor layer such as blue light or ultraviolet light. Since it is a semiconductor substrate, conductivity is obtained by doping, and one electrode can be taken out from the back surface of the substrate. In addition, no matter which of the above materials is used, the lattice constant does not match with GaN, and lattice matching cannot be taken, but by performing selective growth in the lateral direction through the mask portion 5 as described above, A second nitride semiconductor layer 6 having a low dislocation density can be grown on the mask portion 5. In the following example, an n-type substrate will be described as an example, but a p-type substrate may be used.

  The first nitride semiconductor layer 2 has a thickness of about 3 μm, for example, and is n-type doped. For example, a low-temperature growth AlGaN-based compound layer 2a and a high-temperature growth GaN layer 2b are formed by a normal epitaxial growth method such as MOCVD. Therefore, it serves as a seed for lattice mismatch relaxation and for the selective growth of the second nitride semiconductor layer 6 to be described later in the lateral direction. In the example shown in FIG. 1, the first nitride semiconductor layer 2 has a two-layer structure. The AlGaN-based compound layer 2a is a lattice mismatch relaxation layer, and the GaN layer 2b is a seed crystal layer. These layers may be a single layer or a superlattice structure. The composition may be a nitride semiconductor layer such as an AlGaN-based compound or GaN, or an InGaN-based compound, depending on the difference in lattice constant between the substrate to be used and the semiconductor layer stacked thereon, and the film thickness is also required. It is set appropriately according to

  The mask portion 5 (51) is provided on the first nitride semiconductor layer 2 and has an opening 53 with a width W, as shown in FIG. The metal film 3 is provided on the physical semiconductor layer 2 side, and the insulating film 4 is provided on the metal film 3.

  The metal film 3 is preferably made of a metal having a high reflectance with respect to light in the blue to ultraviolet region, such as Al, Ag, and Au. 2, the metal film 3 includes a first metal film 3a provided on the first nitride semiconductor layer 2 side and a second metal film 3b provided on the first metal film 3a. The second metal film 3b is made of the aforementioned material, and the first metal film 3a is made of a metal having a melting point higher than the growth temperature of the semiconductor stacked portion 10, thereby The material of the metal film 3b is preferable because it can prevent diffusion without being alloyed with the semiconductor layer. For example, W, Ti, Pd or the like is preferably used as the first metal film 3a. It is optimal to form the first metal film 3a to about 10 to 200 nm and the second metal film 3b to about 10 to 200 nm.

The insulating film 4 is formed of a material such as SiO ₂ or Si ₃ N ₄ on which a semiconductor layer cannot be directly epitaxially grown to a thickness of about 200 nm by sputtering or the like. The insulating film 4 prevents the second nitride semiconductor layer 6 from growing directly on the first nitride semiconductor layer 2. If the insulating film 4 is formed to have a mask function, a step difference occurs as the thickness decreases. It is difficult and preferable.

  The metal film 3 and the insulating film 4 are sequentially provided on the entire surface of the first nitride semiconductor layer 2 in a wafer state, and then patterned to form groove-shaped openings (grooves extending in a direction perpendicular to the paper surface in FIG. 2). A portion 53 is formed. As will be described later, the opening 53 is provided by causing the second nitride semiconductor layer 6 to be selectively grown in the lateral direction using the first nitride semiconductor layer 2 exposed in the opening 53 as a seed and the second nitride. This is for reducing the dislocation density of the semiconductor layer 6.

  When the semiconductor light emitting device shown in FIG. 1 is manufactured, the width M1 (see FIG. 3) of the mask portion is formed to be about 10 to 15 μm in order to realize lateral selective growth. If the mask portion interval W is too wide, the vertical growth with a high threading dislocation density occurs, the lateral selective growth with a low dislocation density does not proceed, and 5 μm for increasing the region for reflecting light in the light emitting layer. The following is preferable. Moreover, since it takes time for crystal growth from the seed of the first nitride semiconductor layer 2 if the mask portion interval W is too narrow, it is preferably 2 μm or more.

  Furthermore, as shown in the cross-sectional explanatory diagram before element isolation in FIG. 3, in order to facilitate element isolation, and based on the difference in thermal expansion coefficient between the Si substrate 1 and the nitride semiconductor multilayer portion 10 in the wafer state. If only the mask portion 52 corresponding to the element isolation region 15 is expanded in order to prevent the warpage of the wafer, the mask width M2 of the isolation region is wider than the mask width M1 of the mask portion 51 inside the element, and is completely on the mask portion 52. In this case, no selective growth occurs in the lateral direction, and elements are naturally separated by the mask portion 52. Therefore, the width M2 of the mask portion 52 in the vicinity of the element isolation region 15 is preferably larger than the mask width M1 of the mask portion 51 in the center portion of the element, specifically about 20 to 80 μm. Thus, by increasing the width M2 of the mask portion 52 in the isolation region 15, even if the difference in thermal expansion coefficient between the Si substrate 1 and the nitride semiconductor layer is large, stress based on the difference in thermal expansion coefficient can be absorbed. And warpage of the substrate can be prevented. In addition, each element can be made independent, and the work of forming a chip from the wafer becomes easy.

  Second nitride semiconductor layer 6 is, for example, an n-type GaN layer and is formed to a thickness of about 5 to 10 μm. The semiconductor layer 6 begins to grow using the first GaN layer 2b exposed from the opening 53 of the mask portion 5 as a seed, and when the surface reaches the mask portion 5, the semiconductor layer 6 selectively grows in the lateral direction. That is, the GaN layer grows faster in the lateral direction than in the longitudinal direction and grows with good crystallinity, and thus grows slightly in the upward direction while growing in the lateral direction. The semiconductor layers grown in the lateral direction from both openings coincide with each other around the central portion of each. Then, after the surface of the mask portion 5 is completely buried, it grows upward, and the second n-type GaN layer (semiconductor layer) 6 is also completely grown on the mask portion 5. The second n-type GaN layer 6 has good crystallinity in the portions excluding both ends (portions that contact the opening 53) on the mask portion 5 and the matching portion in the central portion, and the dislocation density is also reduced by an order of magnitude. Become.

The semiconductor stacked portion 10 on the second n-type GaN layer 6 is a semiconductor stacked portion constituting a normal light emitting diode. That is, in the example shown in FIG. 1, the n-type layer 7 made of Si-doped GaN is about 1 to 10 μm, and consists of an undoped InGaN-based compound / GaN MQW structure (for example, 1 to 3 nm of In _0.17 Ga _0.83 N). The active layer 8 consisting of a multi-quantum well structure in which 3 to 8 pairs of well layers and 10 to 20 nm In _0.01 Ga _0.99 N barrier layers are laminated is about 0.05 to 0.3 μm in total, doped with Mg The p-type layer 9 made of GaN is formed by providing about 0.2 to 1 μm.

  In addition, the structure of the semiconductor lamination part 10 is laminated | stacked on a required structure according to the semiconductor element to manufacture, and also in the case of LED, it is not limited to the above example, The n-type layer 7 and the p-type layer 9 are In addition, a multilayer structure in which a layer (barrier layer) having a large band gap energy is provided on the active layer side, a superlattice structure or a gradient layer can be provided between semiconductor layers having different compositions, and the second layer The nitride semiconductor layer 6 may also serve as an n-type layer or a p-type layer. Further, the active layer 8 is not limited to the multiple quantum well structure, and may be a bulk structure or a single quantum well (SQW) structure. Furthermore, in this example, the active layer 8 is sandwiched between the n-type layer 7 and the p-type layer 9, but the heterojunction structure in which the n-type layer and the p-type layer are directly joined is also used. Good. In short, when an LED is configured, the n-type layer 7 and the p-type layer 9 may be provided so as to form a light emitting layer. In the above-described example, the example is an LED. Even in the case of an LD, an LD having a high crystallinity and a small leakage current can be obtained if the structure of the semiconductor stacked portion is a stacked structure for LD.

Next, a method for manufacturing the light emitting diode will be described. For example, using an epitaxial growth apparatus such as MOCVD, the substrate temperature is set to about 1100 ° C. and thermal cleaning is performed in an H ₂ atmosphere. Thereafter, the substrate temperature is set to about 400 to 500 ° C., and ammonia gas (NH ₃ ) which is a group V source gas, trimethyl gallium (TMG) and trimethylaluminum (TMA) n-type dopants which are group III source organic metals. SiH ₄ as a gas is introduced, the Si-doped n-type first Al _0.05 Ga _0.95 N layer 2a is set to about 0.01 to _0.05 μm, the substrate temperature is set to about 900 to 1100 ° C., and the GaN layer 2b is formed. 1 to 3 μm.

Next, the substrate is taken out from the growth apparatus, and for example, a Ti film is formed in a thickness of about 10 to 200 nm, an Ag film is formed in a thickness of about 10 to 200 nm, and a SiO ₂ film is formed in a thickness of about 200 to 500 nm using a sputtering apparatus or a vapor deposition apparatus. Thereafter, a resist film is provided on the SiO ₂ film, patterned, and etched by stripping the SiO ₂ film using an HF aqueous solution, the Ag film using an HCl + HNO ₃ aqueous solution, and the Ti film using an HF aqueous solution. An opening is formed in a shape, and a striped mask layer 3 is formed.

Then, it is again put in a growth apparatus such as an MOCVD apparatus, and in addition to the above-mentioned gas as a source gas, trimethylindium (TMIn) of In, cyclopentadienylmagnesium (Cp ₂ Mg) or dimethylzinc (as a p-type dopant) A necessary gas such as DMZn) is introduced together with hydrogen as the carrier gas, and the second n-type GaN layer 6 and the semiconductor layers of the semiconductor stacked portion 10 are grown to the above-described thicknesses. In this case, the n-type GaN layer 6 easily grows in the horizontal direction when the substrate temperature is high, and easily grows in the vertical direction when the substrate temperature is low. The n-type layer 7 grows at a substrate temperature of about 950 to 1100 ° C., the active layer 8 grows at a substrate temperature of about 700 to 770 ° C., and each subsequent layer is grown again at the substrate temperature. Is grown at about 950 to 1100 ° C. In addition, in order to change the composition of In or Al in an InGaN-based compound or an AlGaN-based compound, it can be changed by controlling the flow rate of TMIn, which is an In source gas, or TMA, which is an Al source gas.

Thereafter, a light-transmitting conductive layer 11 made of, for example, ZnO and capable of making ohmic contact with the p-type layer 9 is provided on the surface of the semiconductor stacked portion 10 to about 0.01 to 5 μm. This ZnO is formed by doping Ga so as to have a specific resistance of about 3 to 5 × 10 ⁻⁴ Ω · cm. The translucent conductive layer 11 is not limited to ZnO, and even a thin alloy layer of about 2 to 100 nm of ITO or Ni and Au can diffuse current throughout the chip while transmitting light. it can.

  Then, after polishing the back surface of the substrate 1 so that the thickness of the substrate 1 is about 100 μm, the n-side electrode 13 is formed by laminating Ti / Au, Cr / Pt / Au, Ni / Au or the like on the back surface. Further, the p-side electrode 12 is formed with a Ti / Au laminated structure on the surface of the translucent conductive layer 7 by a lift-off method, and finally the entire chip is covered with a SiON film (not shown) by a plasma CVD method to form an electrode portion. An opening is formed. Thereafter, the wafer is chipped to form a light emitting element chip having the structure shown in FIG.

  According to the present invention, since the nitride semiconductor layer is laminated on the semiconductor substrate, one electrode can be formed on the back surface of the substrate, and a vertical element in which a pair of electrodes are formed above and below the chip. be able to. However, even when such a semiconductor substrate is used, the n-side electrode 12 can be formed on the n-type layer 7 which is exposed by etching a part of the laminated semiconductor laminated portion 10 by dry etching. Even with this structure, since the thermal conductivity of the substrate is better than when a conventional sapphire substrate is used, there is an effect of applying the present invention in that an element in which the light emission efficiency does not decrease until high temperature and high output can be obtained. .

It is sectional explanatory drawing of LED which is one Embodiment of the nitride semiconductor element by this invention. It is an expanded sectional explanatory view of the mask part vicinity by this invention. FIG. 4 is a cross-sectional explanatory diagram of the nitride semiconductor device according to the present invention before device separation. It is a figure which shows the structural example of LED using the conventional nitride semiconductor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 1st nitride semiconductor layer 3 Metal film 4 Insulating film 5 Mask part 6 2nd nitride semiconductor layer 10 Semiconductor laminated part

Claims (3)

  A semiconductor substrate, a first nitride semiconductor layer provided on the semiconductor substrate, a mask portion provided on the first nitride semiconductor layer and having an opening, and on the mask portion from the opening The mask comprising: a second nitride semiconductor layer selectively grown in a lateral direction; and a semiconductor stacked portion in which the nitride semiconductor layer is stacked so as to form a light emitting layer on the second nitride semiconductor layer. A nitride semiconductor light-emitting element, the portion of which comprises a metal film provided on the first nitride semiconductor layer side and an insulating film provided on the metal film.   The metal film has at least a two-layer structure of a first metal film provided on the first nitride semiconductor layer side and a second metal film provided on the first metal film, 2. The nitride semiconductor light emitting element according to claim 1, wherein the metal film is made of a metal having a melting point higher than a growth temperature of the semiconductor stacked portion, and the second metal film is made of a metal that reflects light generated in the light emitting layer. .   3. The nitride semiconductor light emitting element according to claim 2, wherein the first metal film is made of at least one of W, Ti, and Pd, and the second metal film is made of at least one of Al, Ag, and Au.

Images