JP2003282945A - Semiconductor light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device the position of whose electrode can be easily recognized, and which can be arranged in a narrow place. <P>SOLUTION: The semiconductor light emitting device 1, whose plane shape is rectangular, and which has p-type and n-type bonding electrodes 2 and 3 arranged on its one face, has arranged the p-type and n-type bonding electrodes in a way it occupies each of two mutually opposing edges, thus turning the space between the p-type and n-type bonding electrodes 2 and 3 into a light emitting area 4. The p-type and n-type bonding electrodes 2 and 3 are arranged along the two mutually opposing edges on the one face and the inside of one end of the two edges sandwiching the former two. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor light emitting device.

[0002]

2. Description of the Related Art In recent years, an ultraviolet to green light emitting device using a nitride compound semiconductor on a sapphire or silicon carbide substrate has been mass-produced, but a thin P layer having a low concentration and a low mobility is formed on a surface layer. Since it is used, a transparent electrode is used to complement the function of the P layer. Even if a transparent electrode is used, light absorption occurs when it is transmitted, so the flip-chip type in which the element is placed upside down so that the substrate faces upward in order to reduce light emission loss at this transparent electrode and improve brightness. Is being considered.

Most light emitting devices using a nitride-based compound semiconductor on a sapphire substrate have P-type and N-type bonding electrodes formed on a part of the upper surface, so that they become the lower part when they are reversed. It is necessary to recognize and bond each of the electrode positions and the positions of the terminal electrodes provided on the element placement substrate.
It may be difficult to recognize both parties.

Further, in the case of a flip-chip type device in which P-type and N-type bonding electrodes are arranged on one surface, the bonding electrodes are arranged at two corners in the diagonal direction, or two facing electrodes are arranged. Since it is arranged in the central part of the side, there is a problem that the current is less likely to be diffused in the area outside the area connecting these electrodes, and uneven brightness is likely to occur.

Further, since the conventional semiconductor light emitting element has a relatively wide width, it has a structure unsuitable for arranging it in a portion having a narrow width.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor light emitting device whose electrode position can be easily recognized by an automatic assembling apparatus or the like. Another object is to provide a semiconductor light emitting element suitable for being arranged in a narrow portion. Another object is to provide a semiconductor light emitting device that is easy to manufacture. Another object is to provide a semiconductor light emitting element with less uneven brightness.

[0007]

According to a first aspect of the present invention, there is provided a semiconductor light emitting device in which P-type and N-type bonding electrodes are arranged on one surface of a device having a rectangular planar shape. In the device, the P-type and N-type bonding electrodes are arranged so as to occupy two opposite sides of the one surface, and light is emitted between the P-type and N-type bonding electrodes. It is characterized in that it is a region.

According to another aspect of the semiconductor light emitting device of the present invention, each of the P-type and N-type bonding electrodes comprises:
It is characterized in that it is arranged in such a manner as to extend along the insides of two opposite sides of the one surface and one ends of the two sides sandwiching the side.

The semiconductor light emitting device of the present invention is characterized in that, as described in claim 3, the width of the device is shorter than the thickness of the device.

According to a fourth aspect of the semiconductor light emitting device of the present invention, the width of the device is shorter than the thickness of the device.

According to a fifth aspect of the semiconductor light emitting device of the present invention, the device has at least two or more semiconductor layers on a substrate transparent to emitted light. .

As described in claim 6, the semiconductor light emitting device of the present invention is characterized in that the semiconductor layer of the device is constituted by a nitride semiconductor layer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a semiconductor light emitting device of the present invention, (a) is a plan view of the semiconductor light emitting device 1, and (b) is a sectional view thereof.

The semiconductor light emitting device 1 has a rectangular planar shape. The semiconductor light emitting device 1 has P-type and N-type bonding electrodes 2 and 3 disposed on one surface thereof. The P-type and N-type bonding electrodes 2 and 3 are arranged so as to occupy two opposite sides of one surface. In this example, the P-type and N-type bonding electrodes 2 and 3 are arranged to face each other so as to occupy each of the opposite short sides of the upper surface of the semiconductor light emitting device 1. The P-type bonding electrode 2 is arranged so as to occupy one short side of the upper surface of the semiconductor light-emitting element 1 facing each other and the corners located on both sides of this short side, and the N-type bonding electrode 3 is a semiconductor. It is arranged so as to occupy the other short side facing each other on the upper surface of the light emitting element 1 and the corners located on both sides of this short side.

P-type and N-type bonding electrodes 2 and 3
Is a plane rectangular shape having a side equal to the length of the short side of the semiconductor light emitting element 1, for example, 90% or more of the length of the short side of the semiconductor light emitting element 1.

The main light emitting region 4 is between the P-type and N-type bonding electrodes 2 and 3. The light emitting region 4 between the bonding electrodes 2 and 3 has a long and narrow shape in the arrangement direction of the electrodes 2 and 3, and has a large area to allow the extra electrodes 2 and 3 to be arranged. Therefore, on the upper surface of the semiconductor light emitting device 1, four or more bonding electrodes 2 or 3 can be arranged in a line in the longitudinal direction. In this way, the upper surface of the semiconductor light emitting device 1 has an elongated rectangular shape. The ratio of the length of the short side to the length of the long side of the upper surface is set to about 1 to 12 as described later, but it can be set to other ratios. In order to make it an elongated element, the upper surface of the element 1 can be set so that the length of its long side is more than twice the length of its short side.
In order to make it more elongated, the upper surface of the element 1 can be set so that the length of the long side thereof is three times or more the length of the short side.

The semiconductor light emitting device 1 is constructed by providing at least two semiconductor layers 7 and 9 of P type and N type on the substrate 5. The substrate 5 corresponds to a flip chip type that extracts light through the substrate 5. In this case, it is preferable to use a transparent one for the emitted light (emission wavelength). However, when the light is not extracted through the substrate 5 by extracting the light on the side opposite to the substrate 5, the emission light (emission wavelength) is used. ) Can be used.

In this embodiment, a sapphire substrate is used as the substrate 5, on which N-type and P-type nitride semiconductors 7,
9, for example, gallium nitride based semiconductor layers are stacked.
A buffer layer 6 may be interposed between the substrate 5 and the N-type semiconductor layer 7 for the purpose of relaxing lattice mismatch. A light emitting layer 8 is provided between the N-type and P-type semiconductor layers 7 and 9.
Are placed. Although various configurations can be adopted as the light emitting layer 8, for example, a multiple quantum well type active layer can be adopted.

One semiconductor layer In this example, a P-type semiconductor layer 9
A part of the light emitting layer 8 is removed, and the other semiconductor layer (in this example, the N type semiconductor layer 7) is exposed from the removed region 10. On this exposed semiconductor layer 7, one bonding electrode (in this example, an N-type bonding electrode 3) is arranged with an ohmic contact electrode 11 interposed.

On the other semiconductor layer, which is the P-type semiconductor layer 9 in this example, an electrode 12 for ohmic contact is formed over almost the entire region of the P-type semiconductor layer 9. The electrode 12 for ohmic contact may be a translucent electrode or a light reflective electrode depending on the purpose.
The electrode 12 for ohmic contact may be an opaque electrode formed in a comb shape or a mesh shape.
Then, the P-type bonding electrode 2 is arranged on the ohmic contact electrode 12.

As the sapphire substrate 5, a substrate having a thickness before growing a semiconductor layer of 100 μm or more, for example, about 300 μm is used. After the semiconductor layer is grown on the substrate 5, the substrate 5 is polished to a thickness of, for example, about 110 μm so that the total thickness of the wafer is 130 μm or less, for example, about 120 μm.

The semiconductor layer on the substrate 5 is etched by about 1 μm by dry etching or the like. By this etching, the P layer and the active layer are selectively removed, and the removed region 10 is formed. After that, the electrodes 12 and 11 for P-type and N-type ohmic contacts are selectively formed. P-type and N-type bonding electrodes 2 and 3 are selectively formed on the ohmic contact electrodes 12 and 11. The bonding electrodes 2 and 3 may be formed of the same material in the same process. This bonding electrode 2, 3
For, it is preferable to use a material containing Sn (tin) in Au (gold) and having a thickness of 3 μm. The bonding electrodes 2 and 3 are light-shielding electrodes.

In this way, a plurality of semiconductor light emitting devices 1 before division are formed on the wafer, and the designed outer dimensions of each semiconductor light emitting device 1 are 100 μm (width) × 1200 μm.
It is (length) × 120 μm (thickness) and has an extremely slender planar shape.

On the undivided wafer on which a plurality of semiconductor light emitting devices 1 are formed, the semiconductor surface is attached to the adhesive sheet so that the substrate 5 side faces up. After the device is placed in this state in the device for division, element division is performed. For element division, a high-power pulse laser is used to form a dividing groove. In this example using a sapphire substrate as a substrate, a short wavelength laser having a wavelength of 500 nm or less is used. Here, the third harmonic of the YAG laser (wavelength 1.06 μm)
An ultraviolet pulsed laser using (355 nm) is used. Other lasers can be used, for example,
A laser with a wavelength of 500 nm or more can also be used.
Further, the fundamental wavelength (1.06 μm) of the YAG laser or its second harmonic can be used.

Laser irradiation is performed from the substrate 5 side,
It can also be performed from the opposite side of the substrate 5. The laser irradiation may be performed until the processed hole formed by the irradiation penetrates the substrate 5, but the laser irradiation is performed by setting the output and the moving speed of the irradiation so that the hole remains in the substrate 5. The hole formed by laser processing, that is, the depth of the dividing groove is preferably such that the remaining thickness of the substrate 5 in the laser processing hole portion is a thickness that facilitates division, for example, 50 μm or less.

Laser irradiation is performed while spraying nitrogen gas onto the laser irradiation portion. By this spray, it is possible to prevent the scattered material from adhering to the light emitting element, and it is possible to effectively cool the irradiation part and suppress the influence of heat.

As the beam profile of the laser light, a Gaussian distribution waveform, that is, a laser waveform having a peak output in the center was used. The focal point of the laser beam was selectively set near the bottom surface of the wafer (back surface of the substrate), the pulse frequency was 10 kHz, and scanning was performed in the X and Y directions at a speed of 1.5 mm / sec to form a dividing groove. The groove had a width of 30 μm and a depth of 90 μm on the upper surface. When the laser irradiation is performed from the side opposite to the substrate 5, the focus of the laser light may be selectively set near the wafer surface (the surface of the substrate). Although the final device isolation was performed using a dividing device,
Since separation is extremely easy, it may be performed while applying pressure using a roller or the like.

The groove formation by laser irradiation may be performed by scanning a plurality of times. For example, the output may be set high in the initial scan and set in the second and subsequent scans to be smaller than that in the previous scan. With this configuration, when the laser irradiation is performed from the substrate 5 side, the energy of the laser decreases as it approaches the substrate semiconductor layer,
The damage given to the semiconductor layer can be reduced.

The dividing groove by laser irradiation may be formed so as to surround substantially the entire circumference of the semiconductor light emitting element 1, that is, to surround four sides with a part of the portion connecting the groove left. When not formed on the entire circumference, it is preferable to preferentially form the dividing groove by laser irradiation at a location where division using the conventional scribing method is difficult. In this example, the semiconductor light emitting device 1
It is preferable to preferentially form the portion along the long side rather than the short side in order to prevent the elongated element 1 from being broken by mechanical stress during division.

It is preferable that the dividing groove is formed by laser irradiation, because the time required for the formation can be shortened, but another forming means such as etching may be used. As the etching, dry etching using a gas containing chlorine, fluorine or the like as a main component can be adopted. Since dry etching alone takes too much time, it is preferable to perform hole formation using both laser irradiation and dry etching. In particular, by performing dry etching at the final stage or after the end of laser irradiation, it is possible to remove (clean) the scattered material (dust) attached to the wall surface of the hole by laser irradiation. As a result, it is possible to suppress light absorption due to scattered matter and improve the light extraction efficiency of the element.

During dry etching, it is necessary to cover the portion other than the portion to be etched with a protective film so as not to be etched.

The width of the semiconductor light emitting device 1 thus formed is shorter than the thickness thereof. Therefore, it is possible to obtain an optimal shape for a light source such as a backlight in which a light source is arranged on the side surface of a thin light guide plate, such as a side edge type backlight. The semiconductor light emitting device 1 may have a shape whose width is longer than its thickness.

As shown in FIG. 2 showing the second embodiment, on the side opposite to the first removal region 10 where the P-type semiconductor layer 9 is partially removed, the P-type semiconductor layer 9 or, in addition thereto, A second removal region 13 is formed by removing a part of the light emitting layer 8 or the N-type semiconductor layer 7 and the buffer layer 6 in addition to these, and the removal region 13 and the end of the P-type semiconductor region 7 adjacent thereto are formed. An insulating coating 14 is formed so as to cover the coating 1.
4 and the P-type semiconductor layer 9 may be provided with the ohmic contact electrode 12, and the P-type bonding electrode 2 may be provided on the ohmic contact electrode 12 on the second removal region 13.

Further, in each of the above-mentioned embodiments, the bonding electrode 3 and the contact electrode 11 have the same shape, but the contact electrode 11 is modified and the third embodiment as shown in FIG. Can also be taken.

The contact electrodes 11 are branch electrodes 11A,
11B is integrally provided, and these electrodes 11A and 11B are P
It extends to the vicinity of the die bonding electrode. The branch electrodes 11A and 11B are arranged along the long side of the element 1 with the P-type semiconductor layer 9 interposed therebetween. Due to the presence of the branch electrodes 11A and 11B, a wide passage for the current flowing through the N-type semiconductor layer 7 can be secured, and the electrostatic breakdown voltage of the element 1 can be increased.

In order to arrange the branch electrodes 11A and 11B,
The first removal region 10 has extended removal regions 10A and 10B extending along the branch electrodes 11A and 11B. Light emitting layer 8, P-type semiconductor layer 9, contact electrode 12
Has a width slightly reduced in order to secure a region necessary for disposing the branch electrodes 11A and 11B.

In each of the above embodiments, the P-type and N-type bonding electrodes 2 and 3 are such that the length of the semiconductor light emitting device 1 in the width direction (the length along the short side) is the short side of the semiconductor light emitting device 1. 4 and 5, the shape may include an arcuate portion other than the rectangular shape as long as the length is equal to the length.

The light emitting element 1 thus formed is
The bonding electrodes 2 and 3 face downward, and the electrodes are positioned and temporarily arranged on the terminal portion to be attached. At the time of this temporary arrangement, the electrodes 2 and 3 occupy the short sides of the element 1. Therefore, if the short sides of the elements are recognized, the positions of the electrodes can be inevitably recognized. Therefore, even if the electrodes 2 and 3 are on the lower side and cannot be seen,
And the electrodes 2 and 3 can be recognized at the same time,
Assembly workability can be improved.

After the temporary arrangement, heating is carried out at a high temperature of about 350 ° C., so that the bonding electrodes 2 and 3 are adhered and fixed to the terminal portions, whereby the main arrangement is carried out. Then, by molding a translucent resin such as an epoxy resin so as to surround the element, an elongated display element can be formed. Of course, the electrodes may be used with the electrodes 2 and 3 facing upward and wiring such as wire bonding may be performed on the electrodes.

When a predetermined driving voltage is applied between the electrodes 2 and 3, the electrode 2, the contact electrode 12, the P-type semiconductor layer 9,
A current flows along the path of the light emitting layer 8, the N-type semiconductor layer 7, the contact electrode 11, and the electrode 3, and the light emitting layer 8 emits light of a predetermined wavelength. This light is extracted to the outside through the substrate 5 or from the side opposite to the substrate 5.

[0041]

According to the present invention, it is possible to provide a semiconductor light emitting device whose electrode positions can be easily recognized by an automatic assembling apparatus or the like. In addition, it is possible to provide a semiconductor light emitting element suitable for being arranged in a narrow portion. Further, it is possible to provide a semiconductor light emitting device that is easy to manufacture. Also,
It is possible to provide a semiconductor light emitting device with less uneven brightness.

[Brief description of drawings]

FIG. 1 is a plan view (a) and a cross-sectional view (b) showing a first embodiment of the present invention.

FIG. 2 is a plan view (a) and a cross-sectional view (b) showing a second embodiment of the present invention.

FIG. 3 is a plan view (a) and a sectional view (b) showing a third embodiment of the present invention.

FIG. 4 is a plan view showing another embodiment of the present invention.

FIG. 5 is a plan view showing another embodiment of the present invention.

[Explanation of symbols]

1 Semiconductor light emitting element 2 Bonding electrode 3 Bonding electrodes 4 light emitting area 5 substrates

Claims (6)

[Claims] 1. A semiconductor light emitting device having P-type and N-type bonding electrodes arranged on one surface of a device having a rectangular planar shape, wherein each of the P-type and N-type bonding electrodes is provided on the one surface. A semiconductor light emitting device, characterized in that it is arranged such that two opposite sides are respectively occupied and a light emitting region is provided between each of the P-type and N-type bonding electrodes. 2. The P-type and N-type bonding electrodes are arranged in such a manner as to respectively extend inside two edges of the one surface facing each other and one ends of the two edges sandwiching the edge. 2. The semiconductor light emitting device according to claim 1, wherein 3. A semiconductor light emitting device, wherein the width of the device is shorter than the thickness of the device. 4. The semiconductor light emitting device according to claim 1, wherein the width of the device is shorter than the thickness of the device. 5. The semiconductor according to claim 1, wherein the element has at least two semiconductor layers on a substrate transparent to emitted light. Light emitting element. 6. The device according to claim 1, wherein the semiconductor layer of the device is a nitride semiconductor layer.
The semiconductor light emitting device according to any one of 1.