JP4099989B2 - Method for forming electrode of n-type nitride semiconductor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device and a method of manufacturing the same of a nitride semiconductor _{(In X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1), in particular, n-type nitride semiconductor layer The present invention relates to a nitride semiconductor device having good ohmic contact between the electrode and an electrode and a method for manufacturing the same.
[0002]
[Prior art]
Nitride semiconductors are used in light-emitting elements such as light-emitting diodes and laser diodes, light-receiving elements such as solar cells and optical sensors, and electronic devices such as transistors and power devices. In particular, light emitting diodes using nitride semiconductors are widely used in traffic lights, large displays, backlight light sources, and the like.
[0003]
In this nitride semiconductor light emitting diode, basically, an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer are sequentially stacked on an insulating substrate such as sapphire, and a p-type nitride semiconductor layer is formed. Since the p-side electrode is formed on the substrate and the electrode cannot be formed on the back surface of the substrate, the p-type nitride semiconductor layer and the active layer are removed by etching or the like, and n is formed on the exposed n-type nitride semiconductor layer. A side electrode is formed and configured. That is, the p-side electrode and the n-side electrode are arranged on the same surface side where the semiconductor layers are stacked.
[0004]
Further, the substrate is removed by polishing or the like, an n-side electrode is formed on the exposed n-type nitride semiconductor layer, and the p-side electrode and the n-side electrode are arranged so as to face each other through the semiconductor layer It can also be.
[0005]
[Problems to be solved by the invention]
However, the exposed n-type nitride semiconductor layer surface is damaged by etching, polishing, etc., and there is a problem that ohmic contact between the n-type nitride semiconductor layer and the electrode cannot be obtained. In addition, although an ohmic contact between the n-type nitride semiconductor layer and the electrode can be obtained by annealing after forming the electrode on the n-type nitride semiconductor layer, there is also a problem that the electrode is altered by annealing. It was. As a result, the adhesive strength between the electrode and the n-type nitride semiconductor layer, a ball formed by wire bonding, a pad electrode formed on the electrode, and the like is weakened, and in some cases, it may be peeled off. Further, there is a problem that the nitride semiconductor is decomposed by annealing.
[0006]
The present invention has been made to solve such a problem, and in particular, a nitride semiconductor device having good ohmic contact between an n-type nitride semiconductor layer and an electrode even when annealing is omitted, and the same An object is to provide a manufacturing method.
[0007]
[Means for Solving the Problems]
N-type nitride semiconductor electrode forming method of the present invention, the n-type nitride semiconductor composed etched or polished to an n-type _{Al Z Ga 1-Z N (} 0 ≦ Z <1), exposing the surface Irradiating the exposed n-type nitride semiconductor with an electromagnetic wave, decomposing the surface of the n-type nitride semiconductor, and forming an electrode on the n-type nitride semiconductor irradiated with the electromagnetic wave. The electromagnetic wave has a wavelength of 370 nm or less, and is irradiated so that energy on the irradiated surface is in a range of 500 to 5000 mJ / cm ² . Moreover, the following can be employ | adopted in combination with the above-mentioned method. The n-type nitride semiconductor is an n-type nitride semiconductor layer stacked on a substrate. The n-type nitride semiconductor is a substrate made of n-type GaN whose surface is exposed by polishing in the surface exposure process of the n-type nitride semiconductor. An oxide layer is formed on the surface of the n-type nitride semiconductor during or after the electromagnetic wave irradiation, and the oxide layer is removed before the electrode forming step. The electromagnetic waves are irradiated in an atmosphere that does not contain oxygen.
Furthermore, other embodiments of the present invention will be described below.
The nitride semiconductor device of the present invention is a nitride semiconductor device having at least an exposed n-type nitride semiconductor layer, and the n-type nitride semiconductor layer is irradiated with electromagnetic waves, and the electromagnetic waves are irradiated. An electrode is formed on the n-type nitride semiconductor layer. Thereby, damage due to etching, polishing, etc. on the surface of the n-type nitride semiconductor layer is removed, and even if annealing is omitted, good ohmic contact between the n-type nitride semiconductor layer and the electrode can be obtained.
[0008]
In addition, an oxide layer is formed on the surface of the n-type nitride semiconductor layer. In this case, even if annealing is omitted, good ohmic contact between the n-type nitride semiconductor layer and the electrode can be obtained.
[0009]
The oxide layer has a thickness of 50 angstroms or less. Thereby, better ohmic contact between the n-type nitride semiconductor layer and the electrode can be obtained.
[0010]
The electrode is at least one selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Re, Mn, Al, Zn, Pt, Au, Ru, Pd, and Rh. An alloy or a layer structure containing Thereby, a better ohmic contact between the n-type nitride semiconductor layer and the electrode can be obtained.
[0011]
In the n-type nitride semiconductor layer electrode forming method of the present invention, the exposed n-type nitride semiconductor layer is irradiated with an electromagnetic wave, and then an electrode is formed on the n-type nitride semiconductor layer irradiated with the electromagnetic wave. It is characterized by that. Thereby, damage due to etching, polishing, etc. on the surface of the n-type nitride semiconductor layer can be removed, and even if annealing is omitted, good ohmic contact between the n-type nitride semiconductor layer and the electrode can be obtained.
[0012]
Further, the electromagnetic wave is irradiated in an atmosphere not containing oxygen. Thereby, better ohmic contact between the n-type nitride semiconductor layer and the electrode can be obtained.
[0013]
The electromagnetic wave has a wavelength of 370 nm or less. Thereby, damages due to etching, polishing, etc. on the surface of the n-type nitride semiconductor layer can be removed more favorably.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The nitride semiconductor device of the present invention is a nitride semiconductor device having at least an exposed n-type nitride semiconductor layer, and the n-type nitride semiconductor layer is irradiated with electromagnetic waves, and the electromagnetic waves are irradiated. An electrode is formed on the n-type nitride semiconductor layer. In the n-type nitride semiconductor layer electrode forming method of the present invention, the exposed n-type nitride semiconductor layer is irradiated with an electromagnetic wave, and then an electrode is formed on the n-type nitride semiconductor layer irradiated with the electromagnetic wave. It is characterized by that.
[0015]
In the nitride semiconductor device of the present invention, the configuration other than the n-type nitride semiconductor layer is not particularly limited, and may be composed of a nitride semiconductor or may be composed of a material other than the nitride semiconductor. As the nitride semiconductor, a semiconductor made of GaN, AlN, InN, or a mixed crystal of In _X Al _Y Ga _1- XYN (0 ≦ X, 0 ≦ Y, X + Y ≦ 1) is used. In addition, in addition to this, B can be used as a group III element, and a part of N can be substituted with P and As as a group V element.
[0016]
In the present invention, the n-type nitride semiconductor is a nitride semiconductor exhibiting an n-type conductivity, and is a nitride semiconductor doped with an n-type impurity or not doped with an n-type impurity (undoped). This includes nitride semiconductors. The n-type impurity is not particularly limited, but a group IV element such as Si, Ge, Sn, S, O, Ti, Zr, or a group VI element can be suitably used, and preferably Si, Ge, Sn. More preferably, Si is used. An undoped nitride semiconductor is included in an n-type nitride semiconductor because it exhibits n-type conductivity due to nitrogen vacancies in the crystal, but a nitride semiconductor doped with an n-type impurity has a desired carrier concentration. Is preferable because it can be easily obtained.
[0017]
Further, in the present invention, the exposed n-type nitride semiconductor layer is not limited to an exposed n-type nitride semiconductor layer in which a heterogeneous substrate such as sapphire or a semiconductor layer is removed by etching, polishing, or the like. This includes a substrate surface in the case of using a substrate made of an n-type nitride semiconductor such as n-type GaN, or an n-type nitride semiconductor layer that is finally stacked and exposed. The present invention is effective for forming a good ohmic contact between the n-type nitride semiconductor layer and the electrode regardless of the presence or absence of damage on the surface of the n-type nitride semiconductor layer.
[0018]
The composition of the n-type nitride semiconductor layer is composed of n-type In _X Al _Y Ga _1- XYN (0 ≦ X, 0 ≦ Y, X + Y ≦ 1), and is not particularly limited, but is preferably n-type _{Al Z Ga 1-Z n (} 0 ≦ Z <1), more preferably consist of Z n-type value is less Al _Z Ga _1-Z n or n-type GaN,. Such a configuration is preferable because an ohmic contact between the n-type nitride semiconductor layer and the electrode is easily obtained.
[0019]
The impurity concentration of the n-type nitride semiconductor layer is not particularly limited, but is preferably in the range of 1 × 10 ¹⁷ / cm ³ to 1 × 10 ²¹ / cm ³ , more preferably 1 × 10 ¹⁸ / cm ³ to 1 ×. Adjust to the range of 10 ¹⁹ / cm ³ . Adjusting to such a range is preferable because the crystallinity of the n-type nitride semiconductor layer is improved and ohmic contact between the n-type nitride semiconductor layer and the electrode is easily obtained.
[0020]
In the present invention, the electromagnetic wave is not particularly limited, but it is preferable to use an electromagnetic wave having a wavelength of 370 nm or less that is absorbed by the nitride semiconductor. Such a laser having an oscillation wavelength of 370 nm or less is not particularly limited. For example, an excimer laser such as ArF (193 nm), KrF (248 nm), XeCl (308 nm), XeF (353 nm), or HeCd (325 nm) is used. Can be mentioned.
[0021]
Irradiation conditions of electromagnetic waves are not particularly limited, but it is sufficient to irradiate the n-type nitride semiconductor layer with electromagnetic waves and irradiate the surface so that the surface is decomposed. Specifically, the energy on the irradiated surface is 500 to 5000 mJ / cm. It is preferable to adjust appropriately according to the type of electromagnetic wave so as to be in the range of ² . When adjusted to such a range, only the surface of the n-type nitride semiconductor layer is decomposed, and an n-type nitride semiconductor layer having good crystallinity that is not damaged is newly exposed. The n-type nitride semiconductor layer thus obtained can be in good ohmic contact with the electrode even if annealing is omitted.
[0022]
Moreover, depending on the irradiation conditions of electromagnetic waves, an oxide layer may be formed on the surface of the n-type nitride semiconductor layer at the time of irradiation or after irradiation. For example, when the n-type nitride semiconductor layer is composed of n-type AlGaN, n-type GaN, or the like, an oxide layer made of an oxide containing Ga is formed. In general, the oxide layer acts as an insulating layer, but it has been confirmed by the present inventor that ohmic contact with the electrode can be obtained even with an n-type nitride semiconductor layer on which the oxide layer is formed. However, since the contact resistance increases as the oxide layer becomes thicker, the oxide layer is preferably adjusted to a thickness of 50 angstroms or less. For these reasons, it is preferable to irradiate electromagnetic waves in an atmosphere that does not contain oxygen. In addition, it is preferable to remove the oxide by wet etching with hydrofluoric acid, hydrochloric acid, aqueous ammonia, or the like, because a better ohmic contact can be obtained.
[0023]
In the present invention, the electrode is selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Re, Mn, Al, Zn, Pt, Au, Ru, Pd, and Rh. An alloy or layer structure containing at least one can be used, preferably an alloy or layer structure containing at least one selected from the group consisting of Ti, Cr, W, Al, Au, Pd, Rh, more preferably A layer structure such as a two-layer structure composed of Ti / Al, Cr / Au, W / Al, and Rh / Al, or a three-layer structure composed of Ti / Pd / Al is used. Such a layer structure is preferable because the electrode and the n-type nitride semiconductor layer have excellent adhesion and good ohmic contact. Also, Ti, Mo, W, Pt, Ni, TiN, RhO, etc. may be laminated on the electrode for the purpose of barrier, and Au is finally laminated for the purpose of strengthening the adhesive force with the ball formed by wire bonding. May be.
[0024]
The method for forming the electrode is not particularly limited, but vapor deposition, sputtering, and the like can be suitably used. The electrode can be formed on the entire surface of the n-type nitride semiconductor layer, but the n-type nitride semiconductor layer has a lower resistance than the p-type nitride semiconductor layer, and the current is n-type. Since it is easy to diffuse in the nitride semiconductor layer, it is not always necessary to form it on the entire surface of the n-type nitride semiconductor layer. The desired position and shape can be obtained by etching using photolithography (dry etching, wet etching, etc.), lift-off, etc. It can also be formed.
[0025]
In the present invention, the growth method of the nitride semiconductor is not particularly limited, but MOVPE (metal organic chemical vapor deposition), MOCVD (metal organic chemical vapor deposition), HVPE (hydride vapor deposition), MBE ( All methods known as nitride semiconductor growth methods such as molecular beam epitaxy can be suitably used. In particular, MOCVD is preferable because it can be grown with good crystallinity. The nitride semiconductor is preferably grown by appropriately selecting various nitride semiconductor growth methods depending on the purpose of use.
[0026]
【Example】
[Example 1]
Hereinafter, Example 1 is demonstrated based on the light emitting diode element shown in FIG.
The present invention is not limited to this, and is applicable to all nitride semiconductor elements (laser diodes, solar cells, photosensors, transistors, power devices, etc.) that form electrodes on the n-type nitride semiconductor layer. be able to.
[0027]
First, a substrate 1 made of sapphire (C-plane) is set in a MOCVD reaction vessel, and the inside of the vessel is sufficiently replaced with hydrogen, and then the substrate temperature is raised to 1050 ° C. while flowing hydrogen to clean the substrate. . In this embodiment, sapphire (C-plane) is used, but as the substrate, a nitride semiconductor substrate such as GaN, AlN, AlGaN, or a different substrate different from the nitride semiconductor can be used. Examples of the heterogeneous substrate include, for example, an insulating substrate such as sapphire or spinel (MgAl ₂ O ₄ ) whose main surface is any of the C-plane, R-plane, and A-plane, SiC (including 6H, 4H, and 3C), Si, A semiconductor substrate such as ZnO, GaAs, or ZnS can be used, and sapphire or spinel is preferably used. Further, the heterogeneous substrate may be off-angled, and it is particularly preferable to use a stepped off-angle substrate because the underlying layer made of a nitride semiconductor is grown with good crystallinity.
[0028]
Subsequently, the temperature is lowered to 510 ° C., hydrogen is used as the carrier gas, TMG (trimethylgallium) and ammonia are used as the source gas, and a buffer layer (not shown) made of GaN is formed on the substrate 1 with a film thickness of about 100 Å. Grow with thickness. This buffer layer can be omitted depending on the type of substrate and the growth method. In addition, AlGaN having a small Al ratio can be used for the buffer layer.
[0029]
Next, after growing the buffer layer, only TMG is stopped and the temperature is raised to 1050 ° C. When the temperature reaches 1050 ° C., TMG and ammonia gas are similarly used as the source gas, and the undoped GaN layer 2 is grown to a thickness of 1 μm.
[0030]
Subsequently, at 1050 ° C., the n-side contact layer 3 made of GaN doped with Si of 4.5 × 10 ¹⁸ / cm ^{3 is} similarly used with a film thickness of 5 μm using TMG, ammonia gas, and silane gas as the source gas. Grow.
[0031]
Next, the silane gas alone is stopped, and a lower layer made of undoped GaN is grown to a thickness of 3000 Å at 1050 ° C. using TMG and ammonia gas. Subsequently, at the same temperature, silane gas is added to add Si 4 An intermediate layer made of GaN doped with 5 × 10 ¹⁸ / cm ³ is grown at a film thickness of 300 Å, and then only the silane gas is stopped and the upper layer made of undoped GaN is grown at a film thickness of 50 Å at the same temperature. The n-side first multilayer film layer 4 consisting of three layers is grown to a thickness of 3350 angstroms.
[0032]
Next, a nitride semiconductor layer made of undoped GaN is grown at the same temperature to a thickness of 40 Å. Next, the temperature is set to 800 ° C., and TMG, TMI (trimethylindium), and ammonia are used to undoped In _{0. A} nitride semiconductor layer made of _.1 Ga _0.9 N is grown to a thickness of 20 Å. By repeating these operations, the n-side second multilayer film layer 5 having a superlattice structure in which a nitride semiconductor layer made of undoped GaN is grown to a thickness of 40 angstroms is alternately stacked by 10 layers, and the n-side second multilayer film layer 5 is 640 angstroms thick. Grow with film thickness.
[0033]
Next, a barrier layer made of undoped GaN is grown to a thickness of 250 Å using TMG and ammonia. Subsequently, TMI is added at the same temperature to grow a well layer made of In _0.3 Ga _0.7 N with a thickness of 30 Å. By repeating these operations, six layers are alternately stacked, and an active layer 6 having a multiple quantum well structure in which a barrier made of undoped GaN is grown to a thickness of 250 Å is grown to a thickness of 1930 Å.
[0034]
Next, a nitride composed of Al _0.15 Ga _0.85 N doped with 5 × 10 ¹⁹ / cm ^{3 of} Mg at 1050 ° C. using TMG, TMA, ammonia, Cp ₂ Mg (cyclopentanedienylmagnesium) The semiconductor layer is grown to a thickness of 40 Å, and subsequently, the temperature is set to 800 ° C., TMG, TMI, ammonia, Cp ₂ Mg are used, and In _0.03 Ga doped with 5 × 10 ¹⁹ / cm ^{3 of} Mg. _{0 . A} nitride semiconductor layer made of ₉₇ N is grown to a thickness of 25 Å. By repeating these operations, five layers are alternately stacked, and a nitride semiconductor layer made of Al _0.15 Ga _0.85 N doped with 5 × 10 ¹⁹ / cm ^{3 of} Mg is grown to a thickness of 40 Å. The p-side multilayer film layer 7 having a superlattice structure is grown to a thickness of 365 mm.
[0035]
Subsequently, at 1050 ° C., a p-side contact layer 8 made of GaN doped with 1 × 10 ²⁰ / cm ^{3 of} Mg using TMG, ammonia, and Cp ₂ Mg is grown to a thickness of 1200 Å, as shown in FIG. A wafer of structure is obtained. After the reaction is completed, the temperature is lowered to room temperature, and the wafer is annealed in a reaction vessel at 700 ° C. in a nitrogen atmosphere to further reduce the resistance of the p-type layer.
[0036]
After annealing, the wafer is taken out from the reaction vessel, and a p-side electrode 9 made of Ni and Au is formed on the surface of the p-side contact layer 8 by vapor deposition to a thickness of 200 angstroms. After forming the electrode, the p-side contact layer 8 and the p-type electrode 9 are brought into ohmic contact by annealing. Subsequently, the p-side contact layer 8 on which the p-side electrode 9 is formed and the dissimilar substrate 11 (here, Si substrate) are bonded via a conductive adhesive (not shown) such as solder.
[0037]
Next, the sapphire substrate is removed by polishing to expose the n-type nitride semiconductor layer (here, the n-side contact layer 3). Subsequently, using an excimer laser (KrF), as shown in FIG. 1, the exposed n-side nitride semiconductor layer is irradiated with electromagnetic waves so that the energy on the irradiated surface is 3000 mJ / cm ² . Here, oxidation of the surface of the n-type nitride semiconductor layer can be prevented by irradiating electromagnetic waves in an atmosphere that does not contain oxygen. In addition, the oxide formed on the surface of the n-type nitride semiconductor layer can be removed by wet etching with hydrofluoric acid, hydrochloric acid, ammonia water, or the like. After the electromagnetic wave irradiation, the n-side electrode 10 is formed by laminating 100 angstroms of Ti and 5000 angstroms of Al on the surface of the n-side contact layer 3. Finally, the positive electrode 12 was formed on the back surface of the dissimilar substrate 11 and then divided to obtain a light emitting diode element having a side length of 1000 μm. The obtained device had Vf (forward voltage) of 3.2 V at If (forward current) of 20 mA, and good ohmic contact between the n-type nitride semiconductor layer and the electrode was obtained. Further, the entire device emitted light uniformly.
[0038]
[Example 2]
In Example 1, a light emitting diode element was obtained in the same manner except that the n-side electrode 10 was laminated with 300 angstroms of Cr and 5000 angstroms of Au. The obtained device had Vf of 3.25 V at If20 mA, and good ohmic contact between the n-type nitride semiconductor layer and the electrode was obtained. Further, as in Example 1, the entire device emitted light uniformly.
[0039]
[Example 3]
In Example 1, a light emitting diode element was obtained in the same manner except that W was stacked at 100 Å and Al was stacked at 5000 Å as the n-side electrode 10. The obtained device had Vf of 3.3 V at If20 mA, and good ohmic contact between the n-type nitride semiconductor layer and the electrode was obtained. Further, as in Example 1, the entire device emitted light uniformly.
[0040]
[Example 4]
In Example 1, a light emitting diode element was obtained in the same manner except that Rh was stacked at 100 Å and Al was stacked at 5000 Å as the n-side electrode 10. The obtained element had Vf of 3.2 V at If of 20 mA, and good ohmic contact between the n-type nitride semiconductor layer and the electrode was obtained. Further, as in Example 1, the entire device emitted light uniformly.
[0041]
[Example 5]
In Example 1, a light emitting diode element was obtained in the same manner except that the n-side electrode 10 was formed by stacking 50 angstroms of Ti, 20 angstroms of Pd, and 5000 angstroms of Al. The obtained device had Vf of 3.17 V at If20 mA, and good ohmic contact between the n-type nitride semiconductor layer and the electrode was obtained. Further, as in Example 1, the entire device emitted light uniformly.
[0042]
[Example 6]
Example 6 will be described based on the light-emitting diode element shown in FIG.
[0043]
First, a substrate made of n-type GaN (C plane) is used as the substrate 1, and a nitride semiconductor layer is grown in the same manner as in Example 1. After the reaction is completed, the temperature is lowered to room temperature, and the wafer is annealed in a reaction vessel at 700 ° C. in a nitrogen atmosphere to further reduce the resistance of the p-type layer.
[0044]
After annealing, the wafer is taken out from the reaction vessel, and the p-side electrode 9 containing Rh is formed on the surface of the p-side contact layer 8 by vapor deposition to a thickness of 1000 angstroms. After forming the electrode, the p-side contact layer 8 and the p-type electrode 9 are brought into ohmic contact by annealing.
[0045]
Next, the GaN substrate is polished to a thickness of 100 μm. Subsequently, in the same manner as in Example 1, an excimer laser (KrF) exposed by polishing was used, and as shown in FIG. 1, the energy on the irradiation surface was 3000 mJ / cm on the GaN substrate exposed by polishing. Irradiate to ² Here, surface oxide can be removed by wet etching with hydrofluoric acid, hydrochloric acid, aqueous ammonia, or the like. After the electromagnetic wave irradiation, the n-side electrode 10 is formed by laminating 100 angstroms of Ti and 5000 angstroms of Al on the surface of the n-side contact layer 3. Finally, the wafer was divided to obtain a light emitting diode element having a side length of 1000 μm. The obtained device had Vf of 3.15 V at If20 mA, and good ohmic contact between the n-type nitride semiconductor layer and the electrode was obtained. Further, the entire device emitted light uniformly.
[0046]
[Comparative Example 1]
In Example 1, a light-emitting diode element was obtained in the same manner except that the irradiation of electromagnetic waves on the n-type nitride semiconductor layer was omitted. The obtained device had Vf of 5.8 V at If of 20 mA. Further, only the vicinity of the n-side electrode 10 emitted light.
[0047]
【The invention's effect】
As described above, according to the nitride semiconductor device and the method of manufacturing the same of the present invention, after the exposed n-type nitride semiconductor layer is irradiated with electromagnetic waves, the electromagnetic waves are irradiated on the n-type nitride semiconductor layer. By forming the electrode, it is possible to remove damage caused by etching, polishing, etc. on the exposed surface of the n-type nitride semiconductor layer, and good ohmic contact between the n-type nitride semiconductor layer and the electrode even if annealing is omitted. Is obtained. Further, by omitting the annealing, it is possible to prevent electrode deterioration and nitride semiconductor decomposition, and to provide an element with excellent reliability.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a wafer for explaining one step of the method of the present invention.
FIG. 2 is a schematic cross-sectional view showing the structure of a wafer according to an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view showing the structure of a light emitting diode element according to an embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view showing the structure of a light-emitting diode device according to another embodiment of the present invention.
[Explanation of symbols]
1 ... substrate,
2 ... Undoped GaN layer,
3 ... n-side contact layer,
4 ... n-side first multilayer film layer,
5 ... n-side second multilayer film layer,
6 ... active layer,
7: p-side multilayer film layer,
8: p-side contact layer,
9 ... p-side electrode,
10: n-side electrode,
11 ... heterogeneous substrate,
12: Positive electrode.

Claims (5)

Etching or polishing an n-type nitride semiconductor composed of n _- type Al _Z Ga _1-Z N (0 ≦ Z <1) to expose the surface thereof; and exposing the exposed n-type nitride semiconductor A step of irradiating an electromagnetic wave to decompose the surface of the n-type nitride semiconductor; and a step of forming an electrode on the n-type nitride semiconductor irradiated with the electromagnetic wave, wherein the electromagnetic wave has a wavelength of 370 nm or less. Irradiation is performed so that the energy on the irradiated surface is in the range of 500 to 5000 mJ / cm ² .   The n-type nitride semiconductor electrode forming method according to claim 1, wherein the n-type nitride semiconductor is an n-type nitride semiconductor layer stacked on a substrate.   The n-type nitride semiconductor according to claim 1, wherein the n-type nitride semiconductor is a substrate made of n-type GaN whose surface is exposed by polishing in a surface exposure step of the n-type nitride semiconductor. Semiconductor electrode forming method.   4. The method according to claim 1, wherein an oxide layer is formed on the surface of the n-type nitride semiconductor during or after the irradiation with the electromagnetic wave, and the oxide layer is removed before the electrode forming step. The electrode formation method of the n-type nitride semiconductor of any one of Claims 1.   4. The method of forming an n-type nitride semiconductor electrode according to claim 1, wherein the electromagnetic wave is irradiated in an atmosphere not containing oxygen.

Images