JP2000036619A - Iii nitride compound semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high luminous intensity and a low drive voltage by forming a positive electrode of an alloy containing at least one type or more of silver, rhodium, ruthenium, platinum, and palladium. SOLUTION: A buffer layer 102, a high carrier concentration n+ type layer 103 and a multiple quantum well structure light emitting layer 104 are formed on a sapphire substrate 101, P type layers 105, 106 and a first thin film metal layer 111 of metal vapor deposition are formed thereon, and a negative electrode 140 is formed on the layer 103. In this case, the layer 111 is constituted of a metal layer connected to the layer 106. A positive electrode 120 is formed of a metal layer made of an alloy containing silver, rhodium, ruthenium, platinum and palladium or one or more types of them. Vanadium layer 141, 143, an aluminum layer 142, a nickel layer 144 and a gold layer 145 are sequentially laminated from on a partial exposure part of the layer 103 on the electrode 140 of a multilayer structure. When these metals are formed of the metal layer containing one or more types, its light emitting intensity can be improved by about 10 to 50%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flip-chip type light emitting device in which a layer made of a group III nitride compound semiconductor is laminated on a substrate, and more particularly to a flip-chip type light emitting device having a high luminous intensity and a low driving voltage. Related to the element.

[0002]

2. Description of the Related Art FIG. 7 shows a light emitting device 4 of a flip chip type.
00 shows a sectional view. 101 is a sapphire substrate, 102
Is a buffer layer made of AlN or GaN, 103 is an n-type GaN layer, 104 is a light emitting layer, and 105 is a p-type AlGa
N layer, 106 is a p-type GaN layer, 120 is a positive electrode, 13
0 is a protective film, and 140 is a multilayer structure negative electrode. Also,
The thick-film positive electrode 120 connected to the layer 106 is conventionally formed of a metal layer of, for example, nickel (Ni) or cobalt (Co) and having a thickness of 3000 °.

[0003]

In order to sufficiently reflect the light emitted from the light emitting layer 104 toward the sapphire substrate 101, a thick-film metal electrode is usually used as the flip-chip type positive electrode 120. However, in the prior art,
Since a metal such as nickel (Ni) or cobalt (Co) is used for the thick film positive electrode 120, the wavelength is 38
The reflection amount of visible light of 0 nm to 550 nm (blue violet, blue, green) was not sufficient, and a sufficient light emission intensity as a light emitting element could not be secured.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a light emitting device having a high luminous intensity and a low driving voltage. Another object is to provide a light emitting element which does not require wire bonding by simplifying the configuration of the electrode portion of the light emitting element by forming an electrode having high reflectivity and high durability.

[0005]

In order to solve the above-mentioned problems, the following means are effective. That is, the first means is a flip-chip type group III nitride compound semiconductor light-emitting device in which a layer made of a group III nitride compound semiconductor is stacked on a substrate, and is connected to a p-type semiconductor layer to emit light. Silver (Ag), rhodium (R)
h), ruthenium (Ru), platinum (Pt), palladium (Pd), or an alloy containing at least one of these metals. However, the thickness of the positive electrode formed of these metals or alloys is 10
Desirably, it is not less than 0 ° and not more than 5 μm.

A second means is that, in the first means, the positive electrode is provided with a multilayer structure formed of a plurality of kinds of metals. However, at least the lower layer (layer relatively close to the p-type semiconductor layer) of the multilayer positive electrode is composed of silver (Ag), rhodium (Rh), ruthenium (Ru), platinum (Pt), and palladium (Pd). ) Or an alloy containing at least one of these metals, the effect of the present invention can be obtained by the operation of the present invention. More preferably, it is preferable that almost all of the metal layers of the positive electrode located within the lower 1000 ° of the positive electrode including the lowermost layer are formed of the above metals or alloys.

[0007] A third means is the method according to the first or second means, wherein cobalt (Co), nickel (Ni), or nickel (Ni) is provided between the p-type semiconductor side layer and the positive electrode.
A first thin-film metal layer made of an alloy containing at least one of these metals is provided.

A fourth means is that, in the above-mentioned third means, the thickness of the first thin-film metal layer is 2 ° or more and 200 ° or less. The thickness of the first thin metal layer is more desirably 5 ° or more and 50 ° or less.

A fifth means is the third means or the fourth means, wherein gold (Au) or an alloy containing gold (Au) is provided between the first thin film metal layer and the positive electrode. A second thin-film metal layer comprising:

A sixth means is the fifth means, wherein the thickness of the second thin metal layer is not less than 10 ° and not more than 500 °.
It is as follows. The thickness of the second thin metal layer is more desirably 30 ° or more and 300 ° or less.

Further, the seventh means includes the first to sixth means.
In any one of the means, the thickness of the positive electrode, or
The thickness of the first positive electrode layer constituting the lowest layer closest to the substrate of the positive electrode having the multilayer structure is set to 0.01 to 5 μm. The thickness of the first positive electrode layer is preferably 0.02 to 2 μm, and more preferably 0.05 to 1 μm.

[0012] The eighth means may include the first to seventh aspects.
In any one of the methods, a positive electrode or a positive electrode second layer made of gold (Au) is formed on the positive electrode first layer.

A ninth means is that, in the above-mentioned eighth means, the thickness of the second layer of the positive electrode is 0.1 to 5 μm. The thickness of the positive electrode second layer is desirably 0.2 to 3 μm, and more desirably 0.5 to 2 μm.

The tenth means may be any one of the first to ninth means according to the first to ninth means.
Titanium (Ti), chromium (C
r) or forming a third positive electrode layer made of an alloy containing at least one of these metals.

An eleventh means is that, in the tenth means, the thickness of the positive electrode third layer is 5 to 1000 °. The thickness of the positive electrode third layer is desirably 10 to 500.
、, and more preferably 15 to 100Å.

In a twelfth aspect, according to the first aspect, the positive electrode is formed of rhodium (Rh) or ruthenium (R).
u) or an alloy containing at least one of these metals, and directly joining this positive electrode to the p-type semiconductor layer.

Further, the thirteenth means includes the above-mentioned second and first means.
In the zeroth or eleventh means, the multilayer structure of the positive electrode includes a first positive electrode layer formed of rhodium (Rh), ruthenium (Ru), or an alloy containing at least one of these metals; Gold (Au) laminated directly on the layer
And a positive electrode formed of titanium (Ti), chromium (Cr), or an alloy containing at least one of these metals, which is directly laminated on the positive electrode second layer. It has a three-layer structure consisting of a total of three layers of the third electrode, and the first positive electrode
Joining the layer directly to the p-type semiconductor layer.

In a fourteenth aspect, in the tenth or thirteenth aspect, the thickness of the first layer of the positive electrode is set to 0.02 to 2.0.
μm, the thickness of the positive electrode second layer is 0.2 to 3 μm, and
The thickness of the third positive electrode layer is set to 10 to 500 °.

Further, a fifteenth means according to the tenth, eleventh, thirteenth, or fourteenth means, wherein silicon oxide (SiO ₂ ), silicon nitride (Si _x N _y), the titanium compound (Ti _x N _y, etc.), or is to laminating the insulating protective film made of polyimide directly. With the above means, the above-mentioned problem can be solved.

[0020]

Function and Effect of the Invention Silver (Ag), rhodium (R
h), ruthenium (Ru), platinum (Pt), and palladium (Pd) have wavelengths of 380 nm to 550 nm (blue purple,
Blue, green) because the metal has a very high light reflectance R with respect to visible light (0.6 <R <1.0), and therefore, these metals or alloys containing at least one or more of these metals Is used for the positive electrode or the positive electrode first layer, the amount of reflection of these visible lights by the positive electrode can be made sufficiently large, and therefore, a sufficient light emission intensity as a light emitting element can be secured. Become like

FIG. 6 is a table summarizing the characteristics of the metal elements used for the positive electrode or the first layer of the positive electrode.
This list will be described in detail later,
The kinds of metal elements are the results of these multifaceted experiments (Fig. 6)
Accordingly, it has been found that the element is the most excellent element as a metal used for the positive electrode or the first layer of the positive electrode.

For example, the above-mentioned metals or alloys have a low contact resistance with the p-type semiconductor layer because of a large work function or the like. Therefore, if these metals are used, a light emitting element with a low driving voltage can be realized at the same time. be able to. In addition, since the above-mentioned metals are noble metals or platinum group elements, the use of these metals improves the corrosion resistance over time with respect to moisture and the like, and also has the effect that a highly reliable electrode can be formed. Obtained at the same time.

In particular, rhodium (Rh) is slightly inferior to silver (Ag) in terms of reflectivity, but in all other physical properties, is superior to other metals, or has properties equal to or higher than those of other metals. Therefore, when viewed comprehensively, it is an optimal material as a metal element used for the positive electrode or the first layer of the positive electrode.

Since ruthenium (Ru) has properties very similar to or similar to rhodium (Rh) in physical properties, the metal element used for the positive electrode or the first layer of the positive electrode is substantially the same as rhodium (Rh). A good material as well.

Further, by providing the first thin-film metal layer, the adhesion of the positive electrode to the p-type semiconductor layer is improved, and the structure of the light emitting element can be further strengthened. This first
The thickness of the thin metal layer is preferably 2 ° or more and 200 ° or less.
If the thickness is less than 2 °, the thickness is too small to obtain sufficient adhesion. If the thickness is more than 200 °, silver (Ag) and rhodium (R
h), ruthenium (Ru), platinum (Pt), palladium (Pd), or a high reflectance due to the action of these alloys cannot be obtained.

By providing the second thin film metal layer, the adhesion of the positive electrode to the p-type semiconductor layer is further improved, and the structure of the light emitting device can be further strengthened. The thickness of the second thin film metal layer is 10 ° or more, 50
0 ° or less is good. If this film thickness is less than 10 °, the film thickness is too thin to obtain strong adhesion,
In this case, it becomes impossible to obtain a high reflectance by the action of the metal or alloy.

Further, the positive electrode first layer has a thickness of 0.01 μm.
The reason for setting the length to not less than m and not more than 5 μm is as follows. That is, if this film thickness is 0.01μm or less, the film thickness is too thin,
If transmitted light that is not reflected is generated, and if the film thickness is 5 μm or more, a large amount of time is required for electrode formation, which is not preferable in terms of productivity.

Further, by providing the positive electrode second layer made of gold (Au), a positive electrode having a film thickness can be obtained without increasing the resistance value of the positive electrode. The thickness of the positive electrode should be at least 0.1 μm or more in order to prevent adverse effects on characteristics due to heat history in the step of forming a bump material, a gold ball, or wire bonding on the positive electrode in a later step. It is desirable. Gold (Au) is a corrosion-resistant material that can be easily formed, and has high bonding strength with a bump material, a gold ball, or wire bonding. Therefore, it is highly desirable as the positive electrode second layer.

The thickness of the second layer of the positive electrode is 0.1 μm or more.
It is desirable that it is not more than μm. If the thickness is less than 0.1 μm, the film thickness is too thin and the effect is small. If the thickness is more than 5 μm, much time is required for electrode formation. Alternatively, if this film thickness is 5 μm or more, the film thickness of the negative electrode is also unnecessarily thickened due to the convenience of processing steps such as bump formation or gold ball formation described later in the third embodiment, which is preferable. Absent.

Further, by providing a positive electrode third layer made of titanium (Ti) or chromium (Cr), for example, a silicon oxide film (SiO ₂ ) is provided between the positive electrode and the negative electrode arranged on the opposite side of the substrate surface. ),
When an insulating layer made of a silicon nitride film (SiN _x ) or polyimide is provided, peeling of the insulating layer from the positive electrode can be suppressed. This can prevent a short circuit due to the bump material when forming the bump. The thickness of the third thin metal layer is preferably 5 ° or more and 1000 ° or less. If the thickness is less than 5 mm, the thickness is too small to obtain a strong adhesion with the insulating layer.If the thickness is more than 1000 mm, the strong adhesion with a connecting member such as a bump material or a gold ball is obtained. It is not preferable because it cannot be obtained.

The multi-layered positive electrode formed as described above has a high light reflectivity and a high durability against intrusion of moisture and the like, so that the protective layer can be simplified, and as a result, wire bonding can be performed. It is also possible to connect to an external electrode without using.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. Note that the present invention is not limited to the following embodiments. (First Embodiment) FIG. 1 is a schematic sectional view of a flip-chip type semiconductor light emitting device 100 according to the present invention. On the sapphire substrate 101, a buffer layer 102 of aluminum nitride (AlN) having a thickness of about 200 ° is provided, and a buffer layer 102 of silicon (Si) doped GaN of about 4.0 μm is formed thereon.
An m ⁺ high carrier concentration n ⁺ layer 103 is formed.

Then, GaN and Ga are formed on the n ⁺ layer 103.
A light emitting layer 104 having a multiple quantum well structure (MQW) made of _0.8 In _0.2 N is formed. On the light emitting layer 104, a p-type layer 105 made of magnesium (Mg) doped Al _0.15 Ga _0.85 N and having a thickness of about 600 ° is formed. Further, a magnesium (Mg) -doped Ga
A p-type layer 106 made of N and having a thickness of about 1500 ° is formed.

The first layer 106 is formed on the layer 106 by metal evaporation.
A thin metal layer 111 has a negative electrode 140 on the n ⁺ layer 103.
Are formed. The first thin-film metal layer 111 comprises a layer 106
And a metal layer made of cobalt (Co) or nickel (Ni) and having a thickness of about 10 °. Positive electrode 12
0 is silver (Ag) and rhodium (R
h), ruthenium (Ru), platinum (Pt), palladium (Pd), or a metal layer made of an alloy containing at least one of these metals.

The negative electrode 140 having a multilayer structure has a thickness of about 175
A vanadium (V) layer 141, an aluminum (Al) layer 142 with a thickness of about 1000, a vanadium (V) layer 143 with a thickness of about 500, and a nickel (Ni) layer 144 with a thickness of about 5000 A gold (Au) layer 145 of about 8000 ° is sequentially laminated on a part of the high carrier concentration n ⁺ layer 103 which is partially exposed. A protective film 130 made of a SiO ₂ film is formed on the uppermost portion. As described above, the positive electrode 120 is made of silver (Ag), rhodium (Rh), ruthenium (Ru), platinum (Pt), palladium (Pd), or a metal made of an alloy containing at least one of these metals. By using the layers, it is possible to improve the luminous intensity by about 10% to 50% compared to the semiconductor light emitting device 400 according to the related art shown in No. 1 and No. 2 in the table of FIG.

(Second Embodiment) FIG. 2 is a schematic sectional view of a flip-chip type semiconductor light emitting device 200 according to the present invention. The light emitting device 200 is obtained by adding the second thin film metal layer 112 to the light emitting device 100 of the first embodiment, and is not different from the light emitting device 100 in other respects. The second thin-film metal layer 112 is formed of a metal layer made of gold (Au) with a thickness of about 150 °, and the first thin-film metal layer 111 made of cobalt (Co) or nickel (Ni) with a thickness of about 10 °. And then formed by metal vapor deposition in the same manner as the first thin film metal layer 111.
By forming the second thin metal layer 112 between the first thin metal layer 111 and the positive electrode 120, the positive electrode 120 can be more firmly connected to the layer 106.

FIG. 3 shows a performance comparison table of the flip-chip type semiconductor light emitting devices 100, 200 and 400.
The table shows that the positive electrode 120 is made of silver (Ag) or rhodium (Rh) in the first embodiment.
Embodiments in which the configuration of the thin-film metal layer 111 is omitted, and particularly in cases corresponding to claims 1 and 12 of the present invention, are also shown (items 3 and 3.1). As can be seen from this table, the semiconductor light emitting device 100 or 2 according to the present invention.
According to the configuration of No. 00, the positive electrode 120 is made of silver (Ag), rhodium (Rh), ruthenium (Ru), platinum (Pt), palladium (Pd), or an alloy containing at least one of these metals. The light emitting intensity of the conventional semiconductor light emitting device 400
(Item No. 1, Item No. 2) can be improved by about 10% to 50%.

In the light emitting elements 400 of Nos. 1 and 2, the first thin metal layer is not provided because the positive electrode 1
20 itself is already formed of cobalt (Co) or nickel (Ni) which is a constituent metal element of the first thin-film metal layer.
This is because the adhesiveness with No. 06 has already been sufficiently ensured. In FIG. 3, light emitting element 400 in which positive electrode 120 is formed of cobalt (Co) or nickel (Ni)
The reason why the relative luminous intensity of (Item No. 1 and Item No. 2) is low is that the reflectance of the metal element constituting the positive electrode 120 is small, and the presence or absence of the first thin film metal layer 111 is as shown in FIG. It does not contribute to the relative brightness.

Rather, on the contrary, silver (Ag) and rhodium (R
h), ruthenium (Ru), platinum (Pt), palladium (Pd), or when the positive electrode 120 is formed of an alloy containing at least one of these metals, the item 3 and the item in FIG. As can be seen from comparison with No. 4, a higher emission intensity can be obtained without the first thin-film metal layer 111 or the second thin-film metal layer 112. That is, according to such a configuration, although the adhesion between the positive electrode 120 and the layer 106 is somewhat inferior, it shows a better value in terms of luminous intensity. This is because the first thin film metal layer 11
This is because light absorption by the first or second thin film metal layer 112 is eliminated.

Further, in particular, the first and second parts in FIG.
A positive electrode 1 made of rhodium (Rh) having a thickness of about 3000 ° is directly formed on the p-type GaN layer 106 without laminating a thin film metal layer.
In the light emitting device 400 in which the light emitting device 20 is formed, the luminous intensity is substantially the same as that of the light emitting device 200 of item 8 and the GaN layer
06 could be obtained. This is due to the high reflectivity of rhodium (Rh) and the strong adhesion to the GaN layer.
Are superior to the light-emitting element 100 of No. 5 on both sides. That is, if the light-emitting element 400 having the item number 3.1 is manufactured, the first and second light-emitting elements 400 are produced due to the characteristics of rhodium (Rh).
A light-emitting element having sufficiently good luminous intensity, adhesion, and the like can be provided without laminating a thin metal layer. Therefore, according to the configuration of Item No. 3.1, the lamination process of the first and second thin-film metal layers can be omitted, and the light-emitting element 400 with high productivity and optimal for mass production can be manufactured. .

In the above embodiment, the thickness of the positive electrode 120 was about 3000 °, but the thickness of the positive electrode 120 was
The thickness may be 100 ° or more and 5 μm or less. Positive electrode 120
If the film thickness is less than 100 [deg.], Light cannot be sufficiently reflected. If it exceeds 5 [mu] m, the deposition time and material are unnecessarily increased, and the production cost is inferior.

Further, in the above embodiment, the thickness of the first thin metal layer was about 10 °, but the effect is exhibited when the thickness of the first thin metal layer is 2 ° or more and 200 ° or less. I do. The film thickness of the first thin-film metal layer 111 is more preferably
5 ° or more and 50 ° or less are preferable. First thin film metal layer 111
If the layer is too thin, the layer 106 and the positive electrode 120 cannot be strongly bonded. If the layer is too thick, light absorption occurs and the luminous intensity decreases.

Further, in the above embodiment, the thickness of the second thin metal layer is about 150 °, but the effect is exhibited when the thickness of the second thin metal layer is 10 ° to 500 °. I do. The thickness of the second thin metal layer 112 is more desirably 30 ° or more and 300 ° or less. If the second thin film metal layer 112 is too thin, the first thin film metal layer 111 and the positive electrode 1
20 cannot be strongly bonded, and if it is too thick, light absorption occurs and the luminous intensity decreases.

In the above embodiment, the positive electrode 120 has a single-layer structure. However, the positive electrode 120 may have a multilayer structure. From the layer 106, the first thin film metal layer 111 or the second thin film metal layer 112, for example, a film thickness of about 50
00Å silver (Ag), about 800Å nickel (N
i) A positive electrode having a thickness of about 1.4 μm may be formed by sequentially depositing gold (Au) having a thickness of about 8000 ° by vapor deposition. Even with such a configuration, it is possible to obtain a high-luminance light-emitting element having sufficiently high reflection efficiency by the positive electrode.

(Third Embodiment) FIG. 4 is a schematic sectional view of a flip-chip type semiconductor light emitting device 300 according to the present invention. Aluminum nitride on sapphire substrate 101
A buffer layer 102 having a thickness of about 200 ° made of (AlN) is provided, and a buffer layer 102 made of GaN doped with silicon (Si) is formed thereon.
A high carrier concentration n ⁺ layer 103 of 4.0 μm is formed. A light emitting layer 104 having a multiple quantum well structure (MQW) made of GaN and Ga _0.8 In _0.2 N is formed on the layer 103. On the light emitting layer 104, a p-type layer 105 made of magnesium (Mg) doped Al _0.15 Ga _0.85 N and having a thickness of about 600 ° is formed. Further, on the p-type layer 105, a p-type layer 106 made of magnesium (Mg) -doped GaN and having a thickness of about 1500 ° is formed.

A positive electrode 120 having a multilayer structure formed by metal deposition (hereinafter, sometimes referred to as a “multiple positive electrode 120”) is provided on the p-type layer 106, and a negative electrode is provided on the n ⁺ layer 103. 140 are formed. Multiple positive electrodes 120
The first positive electrode layer 121 bonded to the p-type layer 106, the second positive electrode layer 122 formed on the first positive electrode layer 121, and the third positive electrode layer formed on the second positive electrode layer 122. This is a three-layer structure of the layer 123.

The first positive electrode layer 121 is a metal layer made of rhodium (Rh) or platinum (Pt) having a thickness of about 0.1 μm and joined to the p-type layer 106. The positive electrode second layer 122 has a thickness of about
This is a metal layer made of 1.2 μm gold (Au). The positive electrode third layer 123 is a metal layer made of titanium (Ti) having a thickness of about 20 °.

The negative electrode 140 having a multilayer structure has a thickness of about 175
A vanadium (V) layer 141, an aluminum (Al) layer 142 with a thickness of about 1000, a vanadium (V) layer 143 with a thickness of about 500, and a nickel (Ni) layer 144 with a thickness of about 5000 A gold (Au) layer 145 of about 8000 ° is sequentially laminated on a part of the high carrier concentration n ⁺ layer 103 which is partially exposed.

A protective film 130 made of a SiO ₂ film is formed between the multiple positive electrode 120 and the negative electrode 140 thus formed. The protective layer 130 is formed by etching the side surface of the light emitting layer 104, the side surface of the p-type layer 105, and the side surface and the upper surface of the p-type layer 106, which are exposed by etching from the n ⁺ layer 103 exposed to form the negative electrode 140. Partly covers the side surfaces of the positive electrode first layer 121 and the positive electrode second layer 122, and part of the upper surface of the positive electrode third layer 123. The thickness of the portion of the protective film 130 made of SiO ₂ covering the positive electrode third layer 123 is 0.5
μm.

As described above, the multiple positive electrodes 120 are composed of a first positive electrode layer made of rhodium (Rh) or platinum (Pt), a second positive electrode layer made of gold (Au), and a positive electrode made of titanium (Ti). The luminous intensity of the light emitting device 300 according to the present invention constituted by the third layer was measured and compared with the conventional light emitting device 400. FIG. 5 shows the results. From this, it was possible to improve the luminous intensity by about 30% to 40% according to the present invention as compared with the light emitting device 400 according to the prior art.

The flip-chip type light emitting device 300 having such a configuration has high luminous intensity and high durability, can largely omit the protective layer 130, and can connect both the positive electrode and the negative electrode to the external electrode. Large areas can be used. For this reason, it is also possible to invert the light emitting element and directly connect it to the circuit board by forming a bump using solder or the like, or forming a gold ball directly on the positive electrode or the negative electrode. Alternatively, the connection with the external electrode may be performed by wire bonding or the like.

In the third embodiment, the multiple positive electrodes 1
The thickness of the multiple positive electrode 1 was about 1.3 μm.
The film thickness of 20 may be 0.11 μm or more and 10 μm or less.
If the thickness of the multiple positive electrode 120 is less than 0.11 μm, light cannot be sufficiently reflected, and strong adhesion to a connecting member such as a bump material or a gold ball cannot be obtained. On the other hand, if the thickness exceeds 10 μm, the deposition time and the material will be longer than necessary, and the production cost will be inferior.

In the third embodiment, the positive electrode
Although the thickness of the layer 121 was 0.1 μm, the effect is exhibited if the thickness of the first positive electrode layer is 0.01 to 5 μm. The thickness of the positive electrode first layer is desirably 0.02 to 2 μm, and more desirably 0.05 to 1 μm. If the positive electrode first layer 121 is too thin, light reflection will be insufficient, and if too thick, the deposition time and material will be unnecessarily long, and the production cost will be inferior.

In the third embodiment, the positive electrode second layer 12
The film thickness of No. 2 was 1.2 μm, but the effect is exhibited if the film thickness of the second positive electrode layer is 0.1 to 5 μm. The thickness of the positive electrode second layer 122 is desirably 0.2 to 3 μm, and more desirably 0.5 to 2 μm. The positive electrode second layer 122 includes:
If it is too thin, it will not be possible to obtain strong adhesion with connection members such as bump materials and gold balls. On the other hand, if too thick, the negative electrode 14
0, the deposition time and the material take longer than necessary for both the positive electrode second layer 122 and the negative electrode 140,
Not preferred.

In the third embodiment, the positive electrode third layer 12
The thickness of the third layer of the positive electrode was
If it is 5 to 1000 mm, the effect is exhibited. The thickness of the positive electrode third layer 123 is desirably 10 to 500 °, more desirably 15 to 100 °. When the positive electrode third layer 123 is too thin, the adhesion to the protective layer deteriorates, and when too thick, the resistance value increases, which is not preferable.

In the third embodiment, titanium (Ti) is used as the third layer of the positive electrode. However, titanium (Ti), chromium (Cr), or a metal thereof is used as the third layer of the positive electrode. An alloy containing at least one or more kinds may be used.

FIG. 6 shows a list in which the characteristics of the metal elements used for the positive electrode or the first layer of the positive electrode are summarized. Each evaluation item to in this list is as follows. Reflectance: for a predetermined amount of light emission from the light emitting layer 104
Evaluation based on the reflection amount of visible light having a wavelength of 380 nm to 550 nm (blue violet, blue, green). Contact resistance (drive voltage): Evaluation of the contact resistance with the GaN layer by the drive voltage of the light emitting element. Adhesion with GaN layer: Evaluation based on the frequency of occurrence of defective portions in a predetermined durability test. Corrosion resistance: Evaluation based on physical properties and properties of each element. Characteristic stability after Au lamination: gold in light emitting element 300
Evaluation based on an increase in drive voltage after the lamination of the positive electrode second layer 122 made of (Au) and a deterioration in the amount of visible light reflection. Comprehensive evaluation (whether commercial mass production is possible): Evaluation based on comprehensive consideration based on the above-mentioned evaluation items (1) and (2) on the premise of mass production of light emitting elements.

In particular, in the case of a flip-chip type compound semiconductor light-emitting device, it is a necessary condition for a product that the evaluation in the above evaluation items is both good (良) or more. 6 can be seen from the list shown in FIG.

In particular, rhodium (Rh) is slightly inferior to silver (Ag) in terms of reflectivity, but all of the other evaluation items 1 to 6 have characteristics superior to other metals.
Alternatively, the material has the same or better characteristics, and it can be seen that the metal element used for the positive electrode or the first layer of the positive electrode is an optimal material.

Since ruthenium (Ru) has properties very similar to or similar to rhodium (Rh) in physical properties, the metal element used for the positive electrode or the first layer of the positive electrode is substantially the same as rhodium (Rh). A good material as well.

The structure of each layer of the light emitting device in the above-described first to third embodiments is a physical or chemical structure when each layer is formed. It goes without saying that a solid solution or a compound is formed between the layers by a physical or chemical treatment such as a heat treatment performed for the purpose of lowering the value of the contact resistance or the like.

In the first to third embodiments, the light emitting layer 104 of the light emitting element has the MQW structure.
The structure of 04 may be an SQW structure or a homozygous structure. The group III nitride compound semiconductor layer forming the light emitting device of the present invention also includes a buffer layer, and these layers are quaternary, ternary, and binary Al _x Ga _y In _1-xy N (0 ≦ x ≦
1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1).

The buffer layer may be made of a metal nitride such as titanium nitride (TiN), hafnium nitride (HfN), zinc oxide (ZnO), magnesium oxide, etc., in addition to the above group III nitride compound semiconductor. Metal oxides such as (MgO) and manganese oxide (MnO) may be used.

As the p-type impurity, magnesium is used.
In addition to (Mg), Group 2 elements such as beryllium (Be) and zinc (Zn) can be used. Further, in order to lower the resistance of the doped p-type semiconductor layer, activation treatment such as electron beam irradiation or annealing may be further performed.

In the above embodiment, the high carrier concentration n ⁺ layer 103 is formed of silicon (Si) -doped gallium nitride (G
aN), these n-type semiconductor layers are
A group III nitride compound semiconductor may be formed by doping a group IV element such as silicon (Si) or germanium (Ge) or a group VI element.

For the substrate for crystal growth, other than sapphire, silicon carbide (SiC), zinc oxide (ZnO), magnesium oxide (MgO), manganese oxide (MnO) or the like may be used.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a flip-chip type semiconductor light emitting device 100 according to the present invention.

FIG. 2 is a schematic sectional view of a flip-chip type semiconductor light emitting device 200 according to the present invention.

FIG. 3 shows flip-chip type semiconductor light emitting devices 100 and 2
00, 400 performance comparison table.

FIG. 4 is a schematic sectional view of a flip-chip type semiconductor light emitting device 300 according to the present invention.

FIG. 5 shows flip-chip type semiconductor light emitting devices 300 and 4
A table showing the luminous intensity of 00.

FIG. 6 is a table summarizing characteristics of a metal element used for the positive electrode or the first layer of the positive electrode.

FIG. 7 is a schematic cross-sectional view of a flip-chip type semiconductor light emitting device 400.

[Explanation of symbols]

 Reference Signs List 101 sapphire substrate 102 AlN buffer layer 103 n-type GaN layer 104 light-emitting layer 105 p-type AlGaN layer 106 p-type GaN layer 111 first thin metal layer 112 second thin metal layer 120 Positive electrode 121 ... Positive electrode first layer 122 ... Positive electrode second layer 123 ... Positive electrode third layer 130 ... Protective film 140 ... Multilayer negative electrode

Claims (15)

[Claims] In a flip-chip type light emitting device in which a layer made of a group III nitride compound semiconductor is laminated on a substrate, a positive electrode connected to a p-type semiconductor layer and reflecting light toward the substrate is formed of silver ( Ag), rhodium (Rh), ruthenium (R
u), platinum (Pt), palladium (Pd), or an alloy containing at least one of these metals. 2. The group III nitride compound semiconductor light emitting device according to claim 1, wherein the positive electrode has a multilayer structure formed of a plurality of types of metals. 3. A first thin-film metal layer made of cobalt (Co), nickel (Ni), or an alloy containing at least one of these metals, between the p-type semiconductor layer and the positive electrode. The group III nitride compound semiconductor light-emitting device according to claim 1, wherein the light-emitting device is provided. 4. The group III nitride compound semiconductor light emitting device according to claim 3, wherein the thickness of the first thin metal layer is 2 ° or more and 200 ° or less. 5. The semiconductor device according to claim 1, further comprising a second thin-film metal layer made of gold (Au) or an alloy containing gold (Au) between the first thin-film metal layer and the positive electrode. The group III nitride compound semiconductor light emitting device according to claim 3 or 4. 6. The group III nitride compound semiconductor light emitting device according to claim 5, wherein the thickness of the second thin film metal layer is 10 ° or more and 500 ° or less. 7. The film thickness of the positive electrode or the thickness of the first positive electrode layer closest to the substrate and constituting the lowermost layer of the multilayer structure is 0.01 to 5 μm. II according to any one of claims 1 to 6
Group I nitride compound semiconductor light emitting device. 8. The positive electrode or a positive electrode second layer made of gold (Au) is formed on the positive electrode first layer. II described in section
Group I nitride compound semiconductor light emitting device. 9. The positive electrode second layer has a thickness of 0.1 to 5 μm.
9. The group III nitride compound semiconductor light emitting device according to claim 8, wherein 10. The positive electrode, the first positive electrode layer, or the second positive electrode layer, titanium (Ti), chromium (Cr),
The group III nitride compound semiconductor according to any one of claims 1 to 9, wherein a positive electrode third layer made of an alloy containing at least one of these metals is formed. Light emitting element. 11. The positive electrode third layer has a thickness of 5 to 1000.
The group III nitride-based compound semiconductor light emitting device according to claim 10, wherein? 12. The positive electrode is made of rhodium (Rh), ruthenium (Ru), or an alloy containing at least one of these metals.
The III-nitride-based compound semiconductor light-emitting device according to claim 1, wherein the III-nitride-based compound semiconductor light-emitting device is directly connected to the p-type semiconductor layer. 13. The positive electrode first layer formed of rhodium (Rh), ruthenium (Ru), or an alloy containing at least one of these metals, and the positive electrode first layer A positive electrode second layer formed of gold (Au), which is directly laminated on; a titanium (Ti), which is directly laminated on the positive electrode second layer,
A three-layer structure of three positive electrode layers formed of chromium (Cr) or an alloy containing at least one of these metals, wherein the first positive electrode layer is the p-type semiconductor; The group III nitride compound semiconductor light emitting device according to claim 2, which is directly bonded to the layer. 14. The positive electrode first layer has a thickness of 0.02 to 2
μm, the thickness of the positive electrode second layer is 0.2 to 3 μm, and
14. The group III nitride compound semiconductor light emitting device according to claim 10, wherein the thickness of the third layer of the positive electrode is 10 to 500 [deg.]. 15. A semiconductor device comprising: a silicon oxide (SiO ₂ ), a silicon nitride (Si _x N _y ), and a titanium compound (Ti _x N
_y, etc.) or an insulating protective film made of polyimide or the like is directly laminated.
The group III nitride compound semiconductor light emitting device according to claim 11, 13 or 14.