JP2006019586A - Manufacturing method of nitride semiconductor light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely divide a nitride semiconductor light emitting element at good yield , and to provide a nitride semiconductor light emitting element of high efficiency in taking out light. <P>SOLUTION: A group III nitride semiconductor light emitting element 10 has a p-type conductive type nitride semiconductor layer 21, and an n-type conductive type nitride semiconductor layer 20 laminated on a sapphire substrate 11. The manufacturing method includes a process in which laser beam is irradiated to the semiconductor layer 21 side of the nitride semiconductor light emitting element 10 to form a groove 23 of V-like cross section with a laser beam shielding cover put thereon, a process to remove a semiconductor layer around the groove 23 by dry etching with an etching cover 24 put thereon, and a process for dividing the nitride semiconductor light emitting element 10 with the groove 23 as a start point. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a group III nitride semiconductor light emitting device in which at least p-type and n-type conductivity type nitride semiconductor layers are stacked on a substrate.

  In general, a nitride semiconductor is stacked on a sapphire substrate. Since the sapphire crystal is a hexagonal crystal, it does not have a cleavage property. Therefore, it was difficult to cut using a scribe point with a diamond at the tip.

Therefore, in the manufacturing method disclosed in Patent Document 1, the first split groove is formed on the line in a desired chip shape from the gallium nitride compound semiconductor layer side of the wafer, and the first split groove is formed on the gallium nitride compound semiconductor. Forming a depth that cuts through a portion of the sapphire substrate through the layer, forming a second dividing groove having a line width narrower than the first line width from the sapphire substrate side of the wafer, And a step of separating the wafer into chips along the first dividing groove and the second dividing groove.
Japanese Patent No. 2861991

  However, the method of dividing a wafer using a scribe point as in Patent Document 1 makes it difficult to accurately grasp the state of the scribe point because of severe wear of the scribe point, and divides the wafer with high accuracy and high yield. Was difficult. Further, since a large force is applied to the substrate during the division, there is a concern about crystal distortion and the like.

  An object of this invention is to provide the manufacturing method which divides | segments the nitride semiconductor light-emitting device with high precision and sufficient yield. Another object of the present invention is to provide a nitride semiconductor light emitting device with high light extraction efficiency.

  In order to achieve the above object, the present invention provides a method for manufacturing a group III nitride semiconductor light emitting device in which at least p-type and n-type conductivity type nitride semiconductor layers are stacked on a substrate. The step of irradiating the layer side with a laser beam to form a groove having a V-shaped cross section, the step of removing a semiconductor layer around the groove by dry etching, and the nitride semiconductor light emitting element from the groove as a starting point And a process.

  Note that a plasma gas containing chlorine and / or fluorine can be used for the dry etching.

  The depth of the groove having the V-shaped cross section may reach the substrate.

  The width of the groove having the V-shaped cross section is preferably at least twice the depth of the groove.

  In addition, when irradiating the laser beam, the surface of the semiconductor layer other than the portion where the groove is formed is covered with a laser beam shielding cover.

  The laser light shielding cover is made of one or more materials selected from Ni, Al, Ti, Pd, Au, and Ag.

  The dry etching may be performed by covering with an etching cover having an opening wider than the width of the groove having the V-shaped cross section.

  Moreover, it is desirable that the opening of the etching cover has a tapered shape that becomes narrower toward the nitride semiconductor light emitting element side.

  The semiconductor layer removed by the dry etching can be a portion damaged by laser light.

  According to the present invention, by forming the taper in the groove by dry etching, the edge of the divided active layer is positioned at the taper portion, so that the emitted light is reflected at the taper portion and nitriding is performed with high light extraction efficiency. A semiconductor light emitting device can be provided.

  Further, by forming the groove with laser light and widening the groove with dry etching, the nitride semiconductor light emitting device can be divided with high accuracy and high yield.

  FIG. 1 is a schematic side sectional view of a nitride semiconductor light emitting device. The nitride semiconductor light emitting device 10 includes an i-GaN buffer layer 12, an n-GaN layer 13, an n-AlGaN cladding layer 14, an i-InGaN active layer 15, a p-AlGaN cladding layer 16, a p- A GaN layer 17 is sequentially stacked, an n-electrode 18 is formed on the n-GaN layer 13 where the n-AlGaN cladding layer 14 is not stacked, and a p-electrode 19 is formed on the p-GaN layer 17. Configured.

  FIG. 2 is a schematic side sectional view of the nitride semiconductor light emitting device after laser light irradiation, and FIG. 3 is a schematic side sectional view of the nitride semiconductor light emitting device after dry etching. 2 and 3, the i-GaN buffer layer 12, the n-GaN layer 13, and the n-AlGaN cladding layer 14 are referred to as an n-type conductivity nitride semiconductor layer 20, and the p-AlGaN cladding layer 16 and the p-GaN. The layer 17 is referred to as a p-type conductivity type nitride semiconductor layer 21 and the i-InGaN active layer 15 is omitted.

  Hereinafter, a wafer dividing method will be described. First, the laser light shielding cover 22 is placed on the nitride semiconductor layer side of the wafer (see FIG. 2). The laser light shielding cover 22 has an opening 22a through which laser light passes, and is made of one or more materials selected from Ni, Al, Ti, Pd, Au, and Ag. In particular, it is preferable to use Ni. Moreover, since it divides | segments in the position of the opening part 22, the opening part 22a is arrange | positioned so that one element after a division | segmentation may include both p and n electrodes.

  Next, laser light is irradiated from the upper part of the laser light shielding cover 22 to form a groove 23 having a V-shaped cross section on the wafer. The depth of the groove 23 preferably reaches the sapphire substrate 11 from the viewpoint of division accuracy. The width of the groove 23 is easily divided when it is twice or more the depth of the groove 23.

  The laser beam has the following advantages compared to the case where a scribe point is used. Since there is no wear like a blade, a steady groove can be formed. The cross-sectional shape of the groove can be controlled to a desired shape. The depth of the groove can be increased. As described above, the laser beam has many advantages, but there is a disadvantage that a processing residue and a thermal reaction layer are generated in about 50 μm on both sides of the formed groove.

  In addition, when a groove is processed from the back surface of the substrate, the influence (processing) of the laser is applied to a portion other than the divided portion (semiconductor layer on the opposite side of the formed groove) on the surface of the semiconductor layer, and the light when the chip is made to emit light May be diffusely reflected in the area, which may reduce the light emitted from the outside.

  When the groove 23 is formed, the etching cover 24 is then placed instead of the laser light shielding cover 22. The etching cover 24 has an opening 24 a wider than the width of the groove 23. It is desirable that the opening 24a has a tapered shape that becomes narrower toward the nitride semiconductor light emitting element 10 side.

  After covering the etching cover 24, dry etching is performed using a plasma gas containing chlorine or / and fluorine to remove the nitride semiconductor layers 20 and 21 around the groove 23 along the tapered shape of the opening 24a. As a result, the width of the groove 23 is increased while having a taper. Here, the periphery of the groove 23 is a portion of the nitride semiconductor layers 20 and 21 damaged by the laser beam, that is, a processing residue and a thermal reaction layer. The processing residue and the heat-reactive layer can be distinguished visually by the difference in color. Note that all of the damaged nitride semiconductor layers 20 and 21 may be removed, or only a part thereof may be removed. The etching cover 24 may also be used as the laser light shielding cover 22.

  After dry etching, the wafer is divided starting from the groove 23 to obtain the nitride semiconductor light emitting device 10. In the nitride semiconductor light emitting device 10 divided in this way, the side wall portion of the groove 23 has an inclination angle θ as shown in FIG. By appropriately forming the tilt angle θ, in the case of a junction down type device in which the junction including the active layer is assembled close to the heat sink, the end of the active layer has the tilt angle θ, so that light extraction is possible. Efficiency is improved. FIG. 4 is a schematic side sectional view of the nitride semiconductor light emitting device 10 in which the optical path is shown. In the figure, the optical path is indicated by an arrow. The probability that the light emitted from the i-InGaN active layer 15 is totally reflected by the side wall of the groove 23 is increased, so that the light extraction efficiency is improved. From this viewpoint, the inclination angle θ is preferably 30 to 90 °, and more preferably 30 to 60 °.

  The emission intensity on the surface of the sapphire substrate 11 was measured when the end of the i-InGaN active layer 15 had an inclination and when it was vertical. FIG. 5 shows a graph of the number of samples (piece) against the brightness measured on the surface of the sapphire substrate 11. Clearly, it can be seen that the emission intensity of the nitride semiconductor light emitting device having the inclined end face (■ in FIG. 5) is stronger than the emission intensity of the nitride semiconductor light emitting element having the vertical end face (♦ in FIG. 5).

  The nitride semiconductor light-emitting device of the present invention can be used as a blue LED, and can be used for LED lighting, full-color displays, automobile headlamps, and the like.

1 is a schematic side sectional view of a nitride semiconductor light emitting device. It is a side cross-sectional schematic diagram of the nitride semiconductor light emitting element after laser beam irradiation. It is a side cross-sectional schematic diagram of the nitride semiconductor light-emitting device after dry etching. It is the side cross-sectional schematic diagram of the nitride semiconductor light-emitting device which described the optical path. It is a graph of the number of samples with respect to the brightness measured on the sapphire substrate surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nitride semiconductor light emitting element 20 N-type conduction type nitride semiconductor layer 21 P-type conduction type nitride semiconductor layer 22 Laser light shielding cover 23 Groove 24 Etching cover

Claims (9)

In a method for manufacturing a group III nitride semiconductor light-emitting device in which at least p-type and n-type conductivity type nitride semiconductor layers are stacked on a substrate,
Irradiating a laser beam to the semiconductor layer side of the nitride semiconductor light emitting device to form a groove having a V-shaped cross section;
Removing the semiconductor layer around the groove by dry etching;
And a step of dividing the nitride semiconductor light emitting element with the groove as a starting point.   2. The method of manufacturing a nitride semiconductor light emitting device according to claim 1, wherein a plasma gas containing chlorine and / or fluorine is used for the dry etching.   3. The method for manufacturing a nitride semiconductor light emitting device according to claim 1, wherein a depth of the groove having the V-shaped cross section reaches the substrate.   4. The method for manufacturing a nitride semiconductor light emitting device according to claim 1, wherein a width of the groove having the V-shaped cross section is twice or more a depth of the groove.   5. The method for manufacturing a nitride semiconductor light emitting element according to claim 1, wherein a surface of the semiconductor layer other than a portion where the groove is formed is covered with a laser light shielding cover during the irradiation with the laser light. .   6. The method for manufacturing a nitride semiconductor light-emitting element according to claim 5, wherein the laser light shielding cover is made of one or more materials selected from Ni, Al, Ti, Pd, Au, and Ag.   The method for manufacturing a nitride semiconductor light emitting element according to claim 1, wherein the dry etching is covered with an etching cover having an opening wider than the width of the groove having the V-shaped cross section.   8. The method of manufacturing a nitride semiconductor light emitting element according to claim 7, wherein the opening of the etching cover has a tapered shape that becomes narrower toward the nitride semiconductor light emitting element side.   9. The method for manufacturing a nitride semiconductor light-emitting element according to claim 1, wherein the semiconductor layer removed by the dry etching is a portion damaged by a laser beam.

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