BACKGROUND

1. Technical Field

The present disclosure relates to nitride semiconductor light-emitting elements, methods for manufacturing a nitride semiconductor light-emitting element, and nitride semiconductor light-emitting devices, and in particular relates to a watt-class high-output semiconductor light-emitting element used in a projector light source and a headlamp for automobiles.

2. Description of the Related Art

Conventionally, as one form for efficiently obtaining a widescreen image, projectors have been widely used as projection-type image display devices which project an enlarged optical image obtained using a spatial light modulation element such as a compact liquid-crystal panel that forms an image corresponding to an image signal onto a screen through a projector lens by illuminating the spatial light modulation element by light from a light source such as a lamp. In such projection-type image display devices exemplified by projectors, the light source generally includes an ultra-high pressure mercury lamp which exhibits high luminescence efficiency in the wavelength range of visible light.

Meanwhile, a light-emitting diode (LED) or a laser which is a semiconductor light-emitting element characterized by high luminance, high definition, low power consumption, a long operational life, etc., have recently begun to be used instead of a high pressure mercury lamp in a light source of a projector. Especially, in a widescreen, high-quality usage such as digital signage and a projector for movie theaters, a laser projector including a watt-class high-output semiconductor laser as a light source has begun to spread. Furthermore, the watt-class high-output semiconductor laser has begun to develop into a light source for vehicle headlamps. As just mentioned, a light source including a semiconductor light-emitting element such as a laser has been spreading to various fields.

In a conventionally known example of this type of semiconductor light-emitting element, a waveguide has different widths at one end portion and the other end portion in the cavity length direction. For example, a semiconductor laser element including a tapered strip waveguide is known (for example, Japanese Unexamined Patent Application Publication No. 2009-295680).

Examples of a semiconductor light-emitting element suitable for a light source of a projector include a nitride-based semiconductor laser which uses a nitride-based material. For example, a light source that emits blue-violet light in a wavelength range of 405 nm is provided using a nitride-based semiconductor laser, blue phosphor, green phosphor, and red phosphor are excited by laser light emitted from the nitride-based semiconductor layer, and blue light, green light, and red light are emitted from these phosphors; thus, a compact, low power consuming laser projector can be provided.

However, unlike a gallium arsenide-based laser used in optical pickups or optical communication, the nitride-based semiconductor laser involves splitting along a crystal face other than a cleavage surface upon an element split. Therefore, the high likelihood of problems such as a split out of an element split line or cracking of a laser element in the process of cutting out an individual laser element from a wafer (the process of obtaining a chip) has been an issue.

For such an issue, Japanese Unexamined Patent Application Publication No. 2011-029224 discloses techniques for splitting an element using a guide trench, for example.FIG. 49is a plan view of semiconductor light-emitting element1000according to Conventional Example 1 disclosed in Japanese Unexamined Patent Application Publication No. 2011-029224. As illustrated inFIG. 49, in semiconductor light-emitting element1000according to Conventional Example 1, semiconductor layer stacked body1200formed on a substrate includes guide trench1201for element splits which extends in the direction of an element split.

Furthermore, Japanese Unexamined Patent Application Publication No. 2007-329459 discloses techniques for splitting an element using a guide trench having a two-step guide trench structure.FIG. 50is a plan view of semiconductor light-emitting element2000according to Conventional Example 2 disclosed in Japanese Unexamined Patent Application Publication No. 2007-329459. As illustrated inFIG. 50, in semiconductor light-emitting element2000according to Conventional Example 2, semiconductor layer stacked body2200formed on a substrate includes first guide trench2201for element splits which is in the form of a projection at a leading end, and further includes a second guide trench2202at the bottom of first guide trench2201.

SUMMARY

However, it is problematic in that manufacturing nitride semiconductor light-emitting elements in quantity is difficult with the conventional methods for manufacturing a semiconductor light-emitting element.

For example, in recent years, a nitride oxide semiconductor light-emitting element in which the position of a waveguide is offset along the width of the element has been studied, but it is not easy to manufacture, in quantity, a nitride semiconductor light-emitting element in which the position of a waveguide is offset along the width of the element while maintaining a structure in which the waveguide has different widths at one end portion and the other end portion.

The first purpose of the present disclosure is to provide, for example, a method for manufacturing a nitride semiconductor light-emitting element by which it is possible to easily manufacture, in quantity, a semiconductor laser element in which a waveguide has different widths at one end portion and the other end portion and the position of the waveguide is offset along the width of the element.

Furthermore, the conventional techniques disclosed in Japanese Unexamined Patent Application Publications No. 2011-029224 and No. 2007-329459 have the problem of failing to sufficiently reduce generation of particles that are due to an element split.

The second purpose of the present disclosure is to provide, for example, a method for manufacturing a nitride semiconductor light-emitting element in which upon an element split, generation of particles can be sufficiently reduced.

In order to achieve the first purpose, a method for manufacturing a first nitride semiconductor light-emitting element according to one aspect of the present disclosure includes: fabricating a semiconductor layer stacked substrate including a semiconductor layer stacked body on a substrate, the semiconductor layer stacked body including a plurality of waveguides extending in a second direction substantially orthogonal to a first direction; fabricating a plurality of bar-shaped substrates by splitting the semiconductor layer stacked substrate along a plurality of first-direction split lines parallel to the first direction, resulting in the plurality of waveguides being cut; and fabricating a plurality of individual elements by splitting each of the plurality of bar-shaped substrates along a plurality of second-direction split lines parallel to the second direction. A waveguide in each of the plurality of individual elements has different widths at one end portion and another end portion and a center line of the waveguide is located off a center of the individual element along the first direction, the semiconductor layer stacked substrate includes a plurality of element forming regions corresponding to the plurality of individual elements, the plurality of element forming regions include a first element forming region and a second element forming region which are adjacent to each other in the second direction, and two of the plurality of second-direction split lines sandwiching the first element forming region and two of the plurality of second-direction split lines sandwiching the second element forming region are misaligned in the first direction.

Furthermore, a first nitride semiconductor light-emitting element according to one aspect of the present disclosure includes: a substrate; and a semiconductor element structure on one surface of the substrate, and the semiconductor element structure includes a waveguide extending in a second direction substantially orthogonal to a first direction. The nitride semiconductor light-emitting element has: a first side surface substantially parallel to the second direction; a second side surface opposite to the first side surface; a third side surface substantially orthogonal to the first side surface and the second side surface; and a fourth side surface opposite to the third side surface. Each of the third side surface and the fourth side surface is a cleavage surface. The nitride semiconductor light-emitting element includes a first recess near the intersection between the first side surface and the third side surface in a plan view. The first recess has a side surface inclined at an angle of at least 45 degrees with respect to the third side surface. The relationship W1≠W2is satisfied where W1is a first width of the waveguide in the fourth side surface and W2is a second width of the waveguide in the third side surface. The waveguide is located offset in the first direction.

In order to achieve the second purpose, a method for manufacturing a second nitride semiconductor light-emitting element according to one aspect of the present disclosure includes: (i) forming a first trench and a second trench in a semiconductor layer stacked substrate along a second direction substantially orthogonal to a first direction in a substrate plane, the first trench and the second trench sandwiching an area in which a plurality of waveguides extending in the second direction are formed, the semiconductor layer stacked substrate including, on a substrate, a semiconductor layer stacked body in which the plurality of waveguides are formed; (ii) splitting the semiconductor layer stacked substrate into segments by cleaving the semiconductor layer stacked substrate in a predetermined split position along the first direction in the substrate plane; (iii) forming a third trench extending in the second direction between the first trench and the second trench in the semiconductor layer stacked substrate; and (iv) splitting the semiconductor layer stacked substrate along the third trench into segments. In (i), a recess is formed in the predetermined split position between the first trench and the second trench.

Furthermore, a second nitride semiconductor light-emitting element according to one aspect of the present disclosure includes: a substrate; and a semiconductor element structure on one surface of the substrate, the semiconductor element structure including a waveguide extending in a second direction substantially orthogonal to a first direction. The nitride semiconductor light-emitting element further includes: a first side surface substantially parallel to the second direction; a second side surface opposite to the first side surface: a third side surface substantially perpendicular to the first side surface and the second side surface; and a fourth side surface opposite to the third side surface. Each of the third side surface and the fourth side surface is a cleavage surface. The nitride semiconductor light-emitting element further includes: a first trench between the second side surface and the waveguide, the first trench extending in the second direction; a second trench between the first side surface and the waveguide, the second trench extending in the second direction; a first recess near an intersection between the first side surface and the third side surface; a second recess near an intersection between the first side surface and the fourth side surface; a first depressed portion depressed toward the second side surface from the first side surface; and a second depressed portion depressed toward the first side surface from the second side surface.

According to the present disclosure, the nitride semiconductor light-emitting element can be easily manufactured in quantity. For example, according to one aspect of the method for manufacturing the first nitride semiconductor light-emitting element, it is possible to easily manufacture, in quantity, a nitride semiconductor light-emitting element in which a waveguide has different widths at one end portion and the other end portion and the position of the waveguide is offset along the width of the element. Furthermore, according to one aspect of the method for manufacturing the second nitride semiconductor light-emitting element, generation of particles upon an element split can be sufficiently reduced, and thus a nitride semiconductor light-emitting element the operation of which is guaranteed for several thousands of hours in the watt-class operating state can be manufactured in quantity. Moreover, according to one aspect of the first nitride semiconductor light-emitting element and the second nitride semiconductor light-emitting element, a nitride semiconductor light-emitting element excellent in mass productivity can be provided.

