WO2013005759A1 - 半導体レーザ素子 - Google Patents
半導体レーザ素子 Download PDFInfo
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- WO2013005759A1 WO2013005759A1 PCT/JP2012/067051 JP2012067051W WO2013005759A1 WO 2013005759 A1 WO2013005759 A1 WO 2013005759A1 JP 2012067051 W JP2012067051 W JP 2012067051W WO 2013005759 A1 WO2013005759 A1 WO 2013005759A1
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- H01S5/00—Semiconductor lasers
- H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
- H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure
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- H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
- H01L24/31—Structure, shape, material or disposition of the layer connectors after the connecting process
- H01L24/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/022—Mountings; Housings
- H01S5/0233—Mounting configuration of laser chips
- H01S5/0234—Up-side down mountings, e.g. Flip-chip, epi-side down mountings or junction down mountings
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- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
- H01S5/0425—Electrodes, e.g. characterised by the structure
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- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
- H01S5/0425—Electrodes, e.g. characterised by the structure
- H01S5/04254—Electrodes, e.g. characterised by the structure characterised by the shape
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- H01S2301/00—Functional characteristics
- H01S2301/17—Semiconductor lasers comprising special layers
- H01S2301/173—The laser chip comprising special buffer layers, e.g. dislocation prevention or reduction
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- H01S2301/00—Functional characteristics
- H01S2301/17—Semiconductor lasers comprising special layers
- H01S2301/176—Specific passivation layers on surfaces other than the emission facet
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- H01S5/00—Semiconductor lasers
- H01S5/0014—Measuring characteristics or properties thereof
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- H01S5/00—Semiconductor lasers
- H01S5/0014—Measuring characteristics or properties thereof
- H01S5/0021—Degradation or life time measurements
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/0201—Separation of the wafer into individual elements, e.g. by dicing, cleaving, etching or directly during growth
- H01S5/0202—Cleaving
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/022—Mountings; Housings
- H01S5/0235—Method for mounting laser chips
- H01S5/02355—Fixing laser chips on mounts
- H01S5/0237—Fixing laser chips on mounts by soldering
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- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/024—Arrangements for thermal management
- H01S5/02476—Heat spreaders, i.e. improving heat flow between laser chip and heat dissipating elements
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- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
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- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
- H01S5/0425—Electrodes, e.g. characterised by the structure
- H01S5/04252—Electrodes, e.g. characterised by the structure characterised by the material
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- H01S5/00—Semiconductor lasers
- H01S5/30—Structure or shape of the active region; Materials used for the active region
- H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
- H01S5/343—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
- H01S5/34333—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
Definitions
- the present invention relates to a semiconductor laser device.
- Junction-down junction is known as a technique for improving the heat dissipation of a semiconductor laser element.
- Junction down junction is a method of mounting the side on which the ridge is formed on a submount or the like (for example, Patent Document 1).
- paragraph 13 of Patent Document 1 describes that the semiconductor laser element is easily tilted with respect to the submount because the ridge has a convex shape.
- the present invention has been made in view of the above problems, and an object of the present invention is to provide a ridge type semiconductor laser device capable of suppressing the inclination at the time of junction-down junction and having high heat dissipation.
- a semiconductor laser device includes: A substrate, a semiconductor portion provided on the substrate and having a ridge on the opposite surface of the substrate, an electrode provided on the ridge, an insulating film provided on the semiconductor portions on both sides of the ridge, A semiconductor laser device including a pad electrode provided on the electrode, the pad electrode side being a mounting surface side, The pad electrode is provided extending on the insulating film, A spacer portion is provided in a part away from the ridge between the semiconductor portion and the pad electrode.
- the semiconductor laser device configured as described above has a pad electrode surface on the ridge and a pad electrode surface on the spacer provided at a position away from the ridge when the junction down mounting is performed on the substrate. Therefore, the inclination at the time of junction down joining can be suppressed. That is, when the spacer portion is not provided, the both sides of the ridge are lowered, and the tilt is caused by the rocking around the ridge. However, by providing the spacer portion at a position away from the ridge as in the present invention, it is supported by at least the ridge and the spacer portion at the time of mounting, so that the inclination at the junction down junction can be suppressed. .
- the spacer portion is provided in a part apart from the ridge between the semiconductor portion and the pad electrode, the spacer portion is formed on almost the entire surface on both sides of the ridge. Does not deteriorate the heat dissipation.
- FIG. 1 is a plan view of a semiconductor laser element according to Embodiment 1.
- FIG. FIG. 2 is a cross-sectional view taken along one-dot chain line A-A ′ in FIG. 1.
- FIG. 2 is a cross-sectional view taken along one-dot chain line B-B ′ in FIG. 1.
- FIG. 2 is a cross-sectional view taken along one-dot chain line C-C ′ in FIG. 1.
- FIG. 2 is a cross-sectional view taken along one-dot chain line D-D ′ in FIG. 1. It is a figure which shows the state by which the semiconductor laser element which concerns on Embodiment 1 was junction-down mounted.
- 6 is a plan view of a semiconductor laser device according to Embodiment 2.
- FIG. 2 is a cross-sectional view taken along one-dot chain line A-A ′ in FIG. 1.
- FIG. 2 is a cross-sectional view taken along one-dot chain line B-B
- FIG. 1 is a plan view of an edge-emitting semiconductor laser device 100 according to an embodiment of the present invention as viewed from above
- FIG. 2 is a cross-sectional view taken along the dashed line AA ′ in FIG. 3 is a cross-sectional view taken along the chain line BB ′
- FIG. 4 is a cross-sectional view taken along the alternate long and short dash line CC ′ of FIG. 1
- FIG. 5 is a cross-sectional view taken along the alternate long and short dash line DD ′ of FIG.
- the lower side of the cross-sectional views shown in FIGS. 2 to 4 are expressed as “lower” and the upper side is expressed as “upper”.
- these positional relationships are only required to be relative, and it goes without saying that they are within the scope of the present invention even if, for example, each figure is turned upside down.
- the semiconductor laser device 100 includes a substrate 1, a semiconductor portion 2 provided on the substrate and having a ridge 2a on the upper side, an electrode 3 provided on the ridge 2a, and both sides of the ridge 2a. Insulating films 4 and 4 ′ provided and a pad electrode 6 provided on the electrode 3 are provided.
- the semiconductor laser element 100 is a so-called junction down mounting element in which the pad electrode 6 side is the mounting surface side.
- a spacer including a first spacer portion 5a and a second spacer portion 5b is partially provided on the insulating film 4, and similarly, the first spacer portion 5a is provided on the insulating film 4 ′.
- a spacer including 'and the second spacer portion 5b' is partially provided.
- the first spacer portion 5a and the first spacer portion 5a ′ are provided on both sides of the ridge 2a in the vicinity of the emission end face so as to be separated from each other, and the second spacer portion 5b and the second spacer portion 5b ′.
- the pad electrode 6 includes a part of the first spacer part 5a, a part of the first spacer part 5a ′, a part of the second spacer part 5b, and a part of the second spacer part 5b ′.
- the electrode 3 and on the insulating films 4 and 4 ′ so as to cover it.
- pads formed on the first spacer portion 5a, the first spacer portion 5a ′, the second spacer portion 5b, and the second spacer portion 5b ′ Since the height of the upper surface of the electrode is higher than the height of the pad electrode on the insulating film formed in the place where the spacer is not provided, the tilt of the semiconductor laser element 100 can be suppressed at the junction down junction. it can.
- the first spacer portion 5a, the first spacer portion 5a ′, the second spacer portion 5b, and the second spacer portion 5b ′ are preferably formed to have substantially the same thickness as the height of the upper electrode 3.
- the height of the upper surface of the electrode 6 can be made substantially the same, and the tilt of the semiconductor laser element 100 can be more effectively suppressed.
- the tilt of the semiconductor laser device 100 can be suppressed at the time of junction-down junction, and the heat dissipation can be further improved. This will be specifically described below.
- FIG. 6 shows a state in which the semiconductor laser element 100 is mounted on the support member 8 in a junction down manner.
- FIG. 6 is a cross-sectional view including the first spacer portion 5a at the time of junction down mounting.
- the pad electrode 6 is connected to the wiring (not shown) of the support member 8 through the conductive member 9.
- the first spacer portion 5a is partially provided on the insulating film 4, and the pad electrode 6 is provided on the first spacer portion 5a.
- the pad electrode 6 when the pad electrode 6 is directly provided on the insulating film 4 without the first spacer portion 5a, the difference in height between the upper surface of the ridge 2a and the upper surface of the insulating film 4 becomes large, so that the inclination is easy.
- the pad electrode 6 By providing the pad electrode 6 on the insulating film 4 via the spacer portion 5a, the difference in height between the upper surface of the ridge 2a and the upper surface of the first spacer portion 5a can be reduced, so that the inclination of the element in the direction perpendicular to the ridge That is, swinging around the ridge can be suppressed.
- the pad electrode 6 is provided on the relatively thin insulating film 4 without the spacer portion interposed therebetween.
- heat dissipation can be improved. That is, when the spacer portion is provided on almost the entire surface on both sides of the ridge 2a, a relatively thick spacer portion with poor thermal conductivity exists between the pad electrode 6 made of a metal having a high thermal conductivity and the semiconductor layer. As a result, heat accumulates in the spacer portion and the temperature rises.
- the spacer portion when the spacer portion is partially provided, heat is effectively transmitted to the pad electrode on the relatively thin insulating film and is radiated by the pad electrode having good heat conduction.
- the portion where the insulating film is formed via the spacer portion and the spacer portion are interposed. If there is a portion where an insulating film is formed (arranged in parallel), the inclination of the semiconductor laser device 100 can be suppressed, and the heat dissipation can be further improved.
- a region for suppressing inclination that is, a region where a spacer portion is provided
- a region for radiating heat ie, a region where no spacer portion is provided
- the substrate 1 is also preferably made of a nitride semiconductor.
- the substrate 1 has conductivity, and the lower electrode 7 is directly formed on the substrate 1.
- a semiconductor containing nitrogen as a "nitride semiconductor” can be typically represented by In x Al y Ga 1-xy N (0 ⁇ x, 0 ⁇ y, x + y ⁇ 1).
- the semiconductor unit 2 can include, for example, a lower clad layer, a lower guide layer, an active layer, an upper guide layer, an upper clad layer, and an upper contact layer in this order from the substrate 1 side (not shown). Furthermore, the semiconductor part 2 has a ridge 2a on its upper side.
- the ridge 2 a is a stripe-shaped convex portion provided on the upper side of the semiconductor portion 2, and is typically obtained by removing the portion other than the ridge from the upper side of the semiconductor portion 2 at an arbitrary depth.
- the upper surface of the semiconductor portion 2 is exposed continuously from the side surface of the ridge 2a to the outside of the ridge.
- the “ridge upper surface”, the “ridge side surface” continuously extending from the upper surface of the ridge 2a to both sides, and the “semiconductor portion upper surface” continuously extending from the side surface of the ridge 2a to the outside, are used separately.
- the semiconductor unit 2 has an emission end face that is a side that emits laser light and a reflection end face that is a side that reflects the laser light.
- the upper side is the emission end face
- the lower side is the reflection end face.
- Each end face can be formed by cleaving or etching.
- the ridge 2a extends in a direction crossing each end face (preferably a direction substantially perpendicular to each end face).
- the edge of the semiconductor portion 2 can be provided with a stepped portion that extends in the extending direction of the ridge 2 a (the depth direction of the paper surface).
- the step portion is covered with an insulating film (insulating films 4 and 4 ′).
- This step has the following significance. That is, as shown in FIG. 6, during the junction down mounting, the support member 8 and the pad electrode 6 are joined by the conductive member 9. At this time, the conductive member 9 may scoop up the side surface of the semiconductor portion 2. Therefore, as shown in FIGS.
- the conductive member 9 can be prevented from creeping up by providing a stepped portion and forming an insulating film on the stepped portion, and the occurrence of leakage due to the creeping up of the conductive member 9 can be prevented. Can be suppressed.
- the stepped portion is not shown in FIG.
- the ridge 2 is shifted laterally from the center of the chip.
- the pad electrode on the ridge is easily damaged when the ridge is in the center. If it does so, a cavity etc. will generate
- the width of the region of the pad electrode for applying the needle is 50 ⁇ m or more, preferably 70 ⁇ m or more.
- the upper electrode 3 is an electrode provided on the ridge 2a.
- the region where the upper electrode 3 and the upper surface of the ridge 2a are in contact can be arbitrarily set. However, as shown in FIG. 1 and the like, it is preferable to set the entire area of the upper surface of the ridge 2a.
- the region where the upper electrode 3 is formed is not limited to the upper surface of the ridge 2a, but can be extended to the upper surface of the semiconductor portion 2 via the insulating films 4 and 4 ′.
- a material of the upper electrode 3 for example, any of Pd, Pt, Ni, Au, Ti, W, Cu, Ag, Zn, Sn, In, Al, Ir, Rh, or ITO can be included.
- the insulating film provided on the right side of the ridge 2a is indicated by reference numeral 4
- the insulating film provided on the left side of the ridge 2a is indicated by reference numeral 4 ′.
- the insulating films 4 and 4 ′ are also referred to as buried films, and are made of a member having a refractive index lower than that of the semiconductor portion 2 in order to easily confine light in the ridge.
- the insulating film generally has a low thermal conductivity. Therefore, it is desirable to form the film as thin as possible within a range that does not affect the light confinement.
- the upper surfaces of the insulating films 4 and 4 ′ are usually lower than the upper surface of the ridge 2a and are formed from the upper surface of the semiconductor portion 2 to the side surface of the ridge 2a.
- a part of the insulating films 4 and 4 ′ may be extended from the side surface of the ridge 2a to the upper surface of the ridge 2a, and an insulating film may be formed on the upper surface of the ridge except for the region where the upper electrode 3 is formed.
- the material include oxides, nitrides, or oxynitrides of Si, Zr, Al, or Zn.
- the basic function of the spacer portion in the present invention is to suppress the inclination of the semiconductor laser element during junction down mounting.
- the spacer portion may be provided on at least a part of the upper surface of at least one of the insulating films 4 or 4 ′.
- the spacer portion is partially formed without being formed on almost the entire surface of the insulating films 4 and 4 ′ on both sides of the ridge 2 a, so that the inclination at the time of mounting can be increased in the portion where the spacer portion is formed.
- good heat conduction is ensured by forming a pad electrode directly on the insulating films 4 and 4 'in the portion where the spacer portion is not formed.
- the spacer portion may be composed of a plurality of spacer portions having various functions in addition to the tilt prevention function.
- first spacer portions 5a and 5a ′ The first spacer portions 5a and 5a ′ shown in FIG. 1 and the like have a function to be described later in addition to the basic function of suppressing the tilt of the semiconductor laser element during the junction down mounting.
- first spacer portions are provided on both sides of the ridge 2a
- the first spacer portion provided on the right side of the ridge 2a is denoted by reference numeral 5a
- the first spacer portion provided on the left side of the ridge 2a Is denoted by reference numeral 5a ′.
- the first spacer portion will be mainly described with reference to the reference numeral 5a, but it goes without saying that the same applies to the first spacer portion 5a ′.
- the first spacer portion 5a is provided on a part of the insulating film 4 and is a member for separating the insulating film 4 and the pad electrode 6 from each other.
- the upper surface of the pad electrode 6 in the lateral region of the ridge 2a can be increased.
- the inclination of the semiconductor laser element 100 at the time of junction down mounting can be suppressed.
- the semiconductor laser device 100 includes the first spacer portions 5a and 5a ′ on the left and right sides of the ridge 2a, the tilt of the device itself can be further suppressed as compared with the case where the first spacer portion is provided on one side of the ridge 2a. it can.
- the first spacer portion 5a can be provided in the vicinity of either the emission end face or the reflection end face (in the present embodiment, the first spacer parts 5a and 5a ′ are provided in the vicinity of the emission end face. ing.).
- the heat dissipation from the semiconductor part 2 to the pad electrode 6 side can be further improved. That is, when a reflecting mirror is formed (for example, sputtering) on the semiconductor laser element, as shown in FIGS. 12 and 13, the bar (semiconductor laser element) is sandwiched by the plate-shaped jig 60 and the end face of the semiconductor laser element is formed. A reflective mirror is formed on the substrate.
- the members constituting the mirror are usually made of a dielectric material having low thermal conductivity. For this reason, the heat from the semiconductor portion 2 is dissipated to the pad electrode 6 side via the mirror component, which may further deteriorate the heat dissipation. Therefore, the first spacer portion 5a is formed in the vicinity of the end face, and the gap with the plate-like jig used when forming the mirror is filled, so that the deposition of the mirror component on the upper surface of the semiconductor portion 2 can be reduced. The heat radiation from the semiconductor part 2 to the support member 8 side can be effectively performed. Examples of the submount material include AlN and SiC. In general, the mirror is formed in a state where a plurality of elements are connected. However, in FIG. 12 and FIG. 13, only one element is illustrated.
- the first spacer portion 5a can be disposed in the vicinity of the ridge 2a.
- the mirror component during sputtering can effectively suppress the deposition on the upper surface of the pad electrode, and the heat radiation from the semiconductor portion 2 to the pad electrode 6 can be further improved.
- a wide step occurs in that portion. Therefore, when fixing to a plate-shaped jig during mirror film formation, a wide gap will be created between the plate and the semiconductor part, and the mirror component is deposited on the semiconductor part through the gap part or the gap. There is a possibility.
- the distance between the ridge 2a and the spacer is preferably less than 10 ⁇ m, more preferably less than 5 ⁇ m, and even more preferably less than 2 ⁇ m.
- the first spacer portion 5a can be an insulating material. Thereby, the leak resulting from the 1st spacer part 5a can be prevented.
- the first spacer portion 5a is disposed in the vicinity of either the emission end face or the reflection end face, when the first spacer portion 5a is made of a conductive material such as a metal that easily expands or contracts,
- a part of the first spacer portion 5a may be extended to come into contact with the semiconductor portion 2 and cause a leak. Therefore, the occurrence of leakage can be further reduced by making the first spacer portion 5a an insulating material with less stretchability and preventing the contact between the first spacer portion 5a and the semiconductor portion 2.
- the insulating material used for the first spacer portion 5a is preferably an oxide, nitride or oxynitride of Si, Zr, Al or Zn, more preferably an oxide of Si, Zr or Al, and further preferably an oxidation of Si. It can be a thing. This is because the formation is easy and the absorption of light is small.
- the upper surface of the first spacer portion 5a can be substantially the same height as the upper surface of the upper electrode 3 (see FIG. 2). Thereby, the inclination of the semiconductor laser element 100 at the time of junction down mounting can be further suppressed. This is because, by setting the upper electrode 3 and the first spacer portion 5a to substantially the same height, the height of the upper surface of the pad electrode 6 to be formed in a later process can be made uniform. For example, when the upper surface of the first spacer portion 5a is higher than the upper surface of the upper electrode 3, the height of the upper surface of the pad electrode 6 to be formed in a later step is higher than the upper electrode 3 on the first spacer portion 5a. Higher than.
- a gap may be formed on the upper electrode 3 when it is fixed with a plate-shaped jig during mirror film formation, and the mirror may be deposited.
- the upper surface of the first spacer portion 5a is lower than the upper surface of the upper electrode 3, the height of the upper surface of the pad electrode 6 to be formed in a later process is higher than that on the upper electrode 3 on the spacer portion 5a. Also lower. Therefore, a gap may be formed on the first spacer portion 5a when the mirror is formed with a plate-shaped jig when forming the mirror, and the mirror may be deposited. Therefore, it is preferable to align the height of the upper electrode 3 and the first spacer portion 5a to such an extent that the mirror is not deposited through a gap.
- the height difference between them can be preferably less than 50 nm, more preferably less than 30 nm.
- a second spacer portion can be further provided on the upper surface of the insulating film provided with the first spacer portion.
- the second spacer portion provided on the right side of the ridge 2a is indicated by reference numeral 5b
- the second spacer portion provided on the left side of the ridge 2a is indicated by reference numeral 5b ′.
- the second spacer portion 5b will be mainly described, but it goes without saying that the same applies to the second spacer portion 5b ′.
- the second spacer portion 5b is a member for separating the insulating film 4 and the pad electrode 6 from each other.
- the upper surface of the pad electrode 6 in the lateral region of the ridge 2a can be raised.
- the swinging around the central axis perpendicular to the central axis of the lens can be suppressed.) That is, when only the first spacer portion 5a is formed on the insulating film 4, in the region excluding the ridge 2a, the first spacer portion 5a is supported through the pad electrode 6, but the first spacer portion 5a is further supported. By providing the two spacer portions 5b, it can be supported at two locations in the resonator length direction, so that the junction down mounting can be performed more stably.
- the second spacer portion 5b can be provided in the vicinity of the other of the emission end surface or the reflection end surface.
- the first spacer portions 5a and 5a ′ are provided in the vicinity of the emission end face, and the second spacer portions 5b and 5b ′ are provided in the vicinity of the reflection end face).
- the second spacer portion 5b can be disposed in the vicinity of the ridge 2a. Thereby, heat dissipation can be improved more. The reason for this is the same as in the case of the first spacer 5a, and is not repeated here.
- the second spacer portion 5b can be made of an insulating material. Thereby, the leak resulting from the 1st spacer part 5a can be prevented. The reason for this is the same as in the case of the first spacer 5a, and is not repeated here.
- the upper surface of the second spacer portion 5b can be substantially the same height as the upper surface of the upper electrode 3 (see FIG. 2). Thereby, the inclination of the semiconductor laser element 100 at the time of junction down mounting can be further suppressed. The reason for this is the same as in the case of the first spacer 5a, and is not repeated here.
- Block portions 5c and 5c ′ In FIG. 1, a block portion provided on the right side of the ridge 2a is indicated by reference numeral 5c, and a block portion provided on the left side of the ridge 2a is indicated by reference numeral 5c ′.
- the block portion 5c provided mainly on the right side of the ridge 2a will be described. However, it goes without saying that the description also applies to the block portion 5c ′ provided on the left side of the ridge 2a.
- the block portion 5c is formed on the insulating film 4 so as to be separated from the pad electrode 6 in a direction perpendicular to the ridge 2a, and a recess is formed between the pad electrode 6 and the block portion 5c (see FIG. 3). Since the concave portion can suppress the useless spread of the conductive member during the junction down mounting, it is possible to suppress the occurrence of leakage due to the conductive member.
- the first spacer portion 5a, the second spacer portion 5b, and the block portion 5c are integrally formed, but each member may be provided individually.
- the 1st spacer part 5a, the 2nd spacer part 5b, and the block part 5c are integrally formed, let the part which connects the 1st spacer part 5a and the 2nd spacer part 5b be the block part 5c.
- the pad electrode 6 covers at least the first spacer portion 5a and the insulating film 4 on a straight line in the resonator length direction.
- the pad electrode 6 does not need to cover the entire upper surface of the first spacer portion 5a, and may be at least partially covered.
- the upper surface of the pad electrode 6 provided on the upper surface of the semiconductor portion 2 via the first spacer portion 5a is higher than the upper surface of the pad electrode 6 provided on the upper surface of the semiconductor portion 2 without passing through the first spacer portion 5a. Is also high.
- the material of the pad electrode 6 can be a metal material having excellent thermal conductivity, and can include, for example, at least one of Ni, Ti, Au, Pt, Pd, and W.
- the pad electrode 6 can integrally cover the upper surface of the first spacer portion 5a, the upper surface of the insulating film 4, and the upper surface of the second spacer portion 5a 'in the resonator length direction. This is because the pad electrode 6 itself can be easily formed, and a large heat dissipation region (a region where the pad electrode 6 is in direct contact with the insulating film 4) can be secured.
- the semiconductor laser element 200 has the spacer portion 50 on the insulating film 4 and does not include the second spacer portion and the block portion. Furthermore, the spacer part 50 is provided not in the vicinity of the end face but in the central part in the extending direction of the ridge 2a. In this configuration, although the improvement of heat dissipation by suppressing the wraparound of the mirror component and the effect of suppressing the leakage by the block part cannot be expected, the tilt prevention and the heat dissipation of the semiconductor laser 200 during junction down mounting can be expected at a certain level.
- an underlayer made of Si-doped Al 0.02 Ga 0.98 N (film thickness 1.6 ⁇ m) and a Si-doped In 0.05 Ga 0.95 N are formed on a wafer-like substrate 1 made of n-type GaN.
- the MQW active layer includes a barrier layer made of Si-doped In 0.03 Ga 0.97 N (film thickness 170 nm) and an undoped In 0.14 Ga 0.86 N (film thickness 3 nm) in this order from the substrate 1 side.
- a well layer made of undoped GaN (thickness 14 nm), a well layer made of undoped In 0.14 Ga 0.86 N (thickness 3 nm), and undoped In 0.03 Ga 0.97 N
- a barrier layer made of (film thickness 70 nm).
- a stripe-shaped ridge 2a having a width of 30 ⁇ m was formed by RIE at a depth of 500 nm at which the upper guide layer was exposed.
- an upper electrode 3 made of ITO was formed on the ridge 2a with a thickness of 200 nm. As shown in FIGS. 1 to 3 and 5, the upper electrode 3 is joined to a portion excluding the peripheral region on the upper surface of the ridge 2 a.
- insulating films 4 and 4 ′ made of SiO 2 were formed to a thickness of 200 nm. As shown in FIGS. 1 to 4, the insulating films 4 and 4 a cover the upper surface of the semiconductor portion 2, the side surfaces of the ridge 2 a, and the peripheral region of the upper surface of the ridge 2 a.
- first spacer portion 5a and 5a made of SiO 2 ', the second spacer portions 5b and 5b', to form the block portion 5c and 5c 'in a thickness of 500 nm.
- the first spacer portion 5a, the second spacer portion 5b, and the block portion 5c are integrally formed.
- first spacer portion 5a ′, the second spacer portion 5b ′, and the block portion 5c ′ are also integrally formed. Yes.
- the distance between each spacer portion and the ridge 2a was 5 ⁇ m.
- the insulating film 4 is exposed between the first spacer portion 5a and the second spacer portion 5b, and the insulating film 4 is interposed between the first spacer portion 5a ′ and the second spacer portion 5b ′. 'Is exposed.
- a pad electrode 6 made of Ni (film thickness 8 nm) / Pd (film thickness 200 nm) / Au (film thickness 800 nm) / Pt (film thickness 200 nm) / Au (film thickness 300 nm) was formed.
- the pad electrode 6 has a rectangular shape in a plan view (FIG. 1) and includes not only the upper electrode 3 but also the first spacer portions 5a and 5a ′, the second spacer portions 5b and 5b ′, the first spacer portion 5a and the second spacer portion 5a.
- the insulating film 4 exposed between the spacer portions 5b and the insulating film 4 ′ exposed between the first spacer portion 5a ′ and the second spacer portion 5b ′ are covered.
- the final layer of 300 nm thick Au is alloyed by eutectic with AuSn during junction down mounting.
- the wafer having the above structure was polished from the substrate side to 80 ⁇ m, and then the wafer was cleaved in a bar shape with the M surface as a cleaved surface to obtain a plurality of bar-shaped wafers. Specifically, by dividing SiO 2 formed across two adjacent elements between two bar-shaped wafers at the center, the first spacer part 5a in one element and the second spacer part 5b in another element (The same applies to the first spacer portion 5a ′ and the second spacer portion 5b ′.). At this time, the width in the resonator length direction of the spacer portions 5a, 5a ′, 5b and 5b ′ in each element was set to 25 ⁇ m. The first spacer portions 5 a and 5 a ′ have one side surface that is flush with the emission end surface of the semiconductor portion 2. Similarly, the second spacer portions 5b and 5b ′ have one side surface flush with the reflection end surface of the semiconductor portion.
- Al 2 O 3 with a film thickness of 132 nm was formed on the exit end face of the bar-shaped wafer to form an exit end face protective film (outgoing side mirror). Moreover, after forming ZrO 2 with a film thickness of 50 nm on the reflection end face of the bar-shaped wafer, a total of 6 pairs of SiO 2 (film thickness 74 nm) / ZrO 2 (film thickness 50 nm) were formed, and the reflection end face protective film (reflection side mirror) It was.
- the bar-shaped wafer is cut in a direction parallel to the ridge, and the semiconductor laser device 100 having a resonator length (length in the direction parallel to the ridge) of 1200 ⁇ m and width (length in the direction perpendicular to the ridge) of 150 ⁇ m is obtained. Obtained.
- the semiconductor laser device 100 was used as a support member 8 and junction-down mounted on a submount made of AlN on which wiring was formed.
- AuSn eutectic was used for the conductive member 6.
- the semiconductor laser device 100 of the example manufactured as described above was effectively suppressed in inclination during junction down mounting, and stable mounting was possible.
- multimode laser oscillation with a dominant wavelength of 445 nm was confirmed.
- ⁇ Comparative example> In order to effectively suppress the tilt at the time of junction-down mounting, a configuration in which 500 nm thick SiO 2 is formed on almost the entire surface of both sides of the ridge 2 a and the entire surface of the pad electrode 6 is made substantially flat is also considered. It is done. However, if configured in this way, the heat dissipation characteristics deteriorate as described above. In order to confirm this, as a comparative example, as shown in FIG. 11, a semiconductor laser device 600 in which SiO 2 is uniformly formed on almost the entire surface of the insulating films 4 and 4 ′ on both sides of the ridge 2a is manufactured. The heat dissipation characteristics were compared with the semiconductor laser device of the example.
- the semiconductor laser device 600 of the comparative example is the same as that of the semiconductor laser device of the embodiment, the first spacer portions 5a and 5a ′, the second spacer portions 5b and 5b ′ and the block portions 5c and 5c ′ formed so as to surround the outer periphery.
- the structure is the same as that of the semiconductor laser device 100 except that SiO 2 covering almost the entire surface of the insulating films 4 and 4 ′ is formed on both sides of the ridge 2a.
- FIG. 8 shows the results of transient thermal resistance measurement.
- the vertical axis represents the relative value of the thermal resistance value, and the horizontal axis represents the energization pulse time.
- the thermal resistance value per PT 0.01 Sec, which is considered to indicate the thermal resistance value between the chip and the submount, and was smaller than that of the comparative example. From this result, it can be understood that the heat dissipation between the semiconductor laser element 100 and the submount is superior to the comparative example.
- this difference in thermal resistance may seem small, when producing a W-class high-power semiconductor laser device, the amount of heat generation increases in the high current region, so there is a large difference in the amount of heat generation due to a slight difference in thermal resistance. Will occur. In fact, it can be understood that even such a slight difference causes a large difference in IL characteristics and life characteristics as will be described later.
- FIG. 9 shows IL characteristics (current-light output characteristics) between the example and the comparative example.
- a solid line is an Example and a broken line is a comparative example.
- the horizontal axis is the current value
- the vertical axis is the relative light output.
- FIG. 10 the life characteristic of an Example and a comparative example is shown.
- a solid line is an Example and a broken line is a comparative example.
- the horizontal axis represents drive time, and the vertical axis represents relative light output.
- the light output decreases little even if driven for a long time, but in the comparative example, the light output greatly decreases if driven for a long time. It is considered that such a result was obtained because the heat dissipation of the example was superior to that of the comparative example.
- the semiconductor laser device 100 of the example according to the present invention can suppress the tilt at the junction-down junction and has high heat dissipation.
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Abstract
Description
基板と、前記基板上に設けられ前記基板の反対側の面にリッジを有する半導体部と、前記リッジ上に設けられた電極と、前記リッジの両側の半導体部上に設けられた絶縁膜と、前記電極上に設けられたパッド電極と、を備え、前記パッド電極側を実装面側とする半導体レーザ素子であって、
前記パッド電極は、前記絶縁膜上に延在して設けられており、
前記半導体部と前記パッド電極の間の前記リッジから離れた一部にスペーサ部が設けられたことを特徴とする。
すなわち、スペーサ部が設けられていない場合には、リッジの両側が低くなっていることからリッジを中心にして揺動することから傾きが生じる。
しかしながら、本発明のように、リッジから離れた位置にスペーサ部を設けることにより、実装時に少なくともリッジとスペーサ部によって、支持されることになるので、ジャンクションダウン接合時の傾きを抑制することができる。
さらに、本発明に係る半導体レーザ素子では、前記半導体部と前記パッド電極の間の前記リッジから離れた一部にスペーサ部が設けられているので、スペーサ部をリッジ両側のほぼ全面に形成したときのように放熱性を悪化させることがない。
以上のように構成された実施形態の半導体レーザ素子では、第1スペーサ部5aと、第1スペーサ部5a’と、第2スペーサ部5bと及び第2スペーサ部5b’の上に形成されたパッド電極の上面の高さを、スペーサが設けられていない場所に形成された絶縁膜上のパッド電極の高さより高くしているので、ジャンクションダウン接合時に、半導体レーザ素子100の傾きを抑制することができる。第1スペーサ部5a、第1スペーサ部5a’、第2スペーサ部5b及び第2スペーサ部5b’は、上部電極3の高さと略同一の厚さに形成されることが好ましく、これにより、第1スペーサ部5a、第1スペーサ部5a’、第2スペーサ部5b及び第2スペーサ部5b’の上に形成されたパッド電極の上面の高さと、リッジ上(電極3上)に形成されたパッド電極6の上面の高さとを、略同一の高さにでき、より効果的に半導体レーザ素子100の傾きを抑えることができる。
さらに、第1スペーサ部5aを含むスペーサ部が部分的に設けられているので、比較的薄い絶縁膜4上にパッド電極6がスペーサ部を介することなく設けられている。これにより、スペーサ部をほぼ全面に設けた場合に比較して、放熱性を向上させることができる。すなわち、スペーサ部をリッジ2aの両側のほぼ全面に設けた場合には、熱伝導率の大きい金属からなるパッド電極6と半導体層の間に比較的厚い熱伝導の悪いスペーサ部がほぼ全面に存在することになり、スペーサ部に熱がこもり温度が上昇する。これに対して、スペーサ部を部分的に設けるようにすると、比較的薄い絶縁膜上のパッド電極に熱が効果的に伝達されて熱伝導が良好なパッド電極により放熱される。
このように、リッジ2aの長手方向に平行な方向(例えば図1に示すC-C’線に沿った方向)に、スペーサ部を介して絶縁膜が形成されている部分とスペーサ部を介することなく絶縁膜が形成されている部分が存在する(並置されている)と、半導体レーザ素子100の傾きを抑制することができ、さらに放熱性を向上させることができる。
基板1には種々の材料を用いることができる。半導体部2が窒化物半導体からなる場合は、基板1も窒化物半導体とすることが好ましい。ここでは、基板1は導電性を有し、基板1に直接下部電極7が形成されている。なお、「窒化物半導体」とは窒素を含む半導体であり、典型的にはInxAlyGa1-x-yN(0≦x、0≦y、x+y≦1)で示すことができる。
半導体部2には種々の材料及び構造を用いることができる。半導体部2は、例えば、基板1側から、下部クラッド層、下部ガイド層、活性層、上部ガイド層、上部クラッド層及び上部コンタクト層を順に備えることができる(図示せず)。さらに、半導体部2はその上側にリッジ2aを有する。リッジ2aは、半導体部2の上側に設けられたストライプ状の凸部であり、典型的には、半導体部2の上側からリッジとなる部分以外を任意の深さで除去することにより得られる。半導体部2は、リッジ2aの側面からリッジ外側に連続してその上面が露出している。なお、本明細書では、「リッジ上面」と、リッジ2aの上面から両側に連続して延伸する「リッジ側面」と、リッジ2aの側面から外側に連続して延伸する「半導体部上面」と、を区別して使用する。
この段差部には、以下のような意義がある。
すなわち、図6に示すようにジャンクションダウン実装時には、支持部材8とパッド電極6が導電部材9により接合されるが、その際に導電部材9が半導体部2側面を這い上がる可能性がある。
そこで、図2、図3に示すように、段差部を設け且つ段差部に絶縁膜を形成することによって導電部材9の這い上がりを防止でき、導電部材9の這い上がりに起因したリークの発生を抑制することができる。なお、図面の理解を容易にするために図1においては段差部を示していない。
上部電極3は、リッジ2a上に設けられる電極である。上部電極3とリッジ2aの上面とが接触する領域は任意に設定することができる。しかしながら、図1等に示すように、リッジ2a上面の略全域とすることが好ましい。なお、上部電極3を形成する領域はリッジ2a上面のみに限られず、絶縁膜4及び4’を介して半導体部2上面まで延在させることもできる。上部電極3の材料としては、例えば、Pd、Pt、Ni、Au、Ti、W、Cu、Ag、Zn、Sn、In、Al、Ir、Rh又はITOのいずれかを含めることができる。
図1において、リッジ2aの右側に設けられた絶縁膜を符号4で示し、リッジ2aの左側に設けられた絶縁膜を符号4’で示す。絶縁膜4及び4’は埋込膜とも称されるものであり、光をリッジ内に閉じ込めやすくするために半導体部2よりも屈折率の低い部材からなる。ジャンクションダウン時には絶縁膜4を介して放熱が行われる。しかしながら、絶縁膜は一般的には熱伝導率が低い。そのため光の閉じ込めに影響を与えない範囲で、できる限り膜厚を薄く成膜することが望ましい。したがって、絶縁膜4及び4’の上面は通常、リッジ2aの上面よりも低く、半導体部2の上面からからリッジ2a側面にわたって形成されている。リッジ2a側面からリッジ2a上面に絶縁膜4及び4’の一部を延在させ、上部電極3が形成される領域を除いてリッジの上面にも絶縁膜を形成するようにしてもよい。その材料としては、例えば、Si、Zr、Al又はZnの酸化物、窒化物又は酸窒化物が挙げられる。
本発明におけるスペーサ部の基本的な機能は、ジャンクションダウン実装時における半導体レーザ素子の傾きを抑制するものである。その基本的な機能を果たすために、スペーサ部は、絶縁膜4又は4’のうち少なくとも一方の上面の少なくとも一部に設けられていればよい。例えば、スペーサ部を一箇所形成する場合、スペーサ部は、パッド電極6の下でかつリッジ2aの両端から最も離れた位置に形成することが好ましい。このようにすると、リッジ2aとスペーサ部で半導体レーザ素子を支持することができ、半導体レーザ素子の傾きを効果的に抑制することができる。
また、スペーサ部は、リッジ2a両側の絶縁膜4,4’上のほぼ全面に形成することなく、部分的に形成されており、これにより、スペーサ部か形成された部分で実装時の傾きを抑制する一方、スペーサ部か形成されていない部分では絶縁膜4,4’上に直接パッド電極を形成することで良好な熱伝導を確保している。
このスペーサ部は、上述のように少なくとも1つあればよいが、上記傾き防止機能の他に種々の機能を併せ持った複数のスペーサ部からなっていてもよい。
図1等に示す第1スペーサ部5a及び5a’は、ジャンクションダウン実装時における半導体レーザ素子の傾きを抑制するという基本機能に加え、さらに後述の機能を有している。
図1においては、リッジ2aの両側に第1スペーサ部が設けられており、リッジ2aの右側に設けられた第1スペーサ部を符号5aで示し、リッジ2aの左側に設けられた第1スペーサ部を符号5a’で示す。以下では主として第1スペーサ部を符号5aについて説明するが、第1スペーサ部5a’についても同様であることは言うまでもない。
第1スペーサ部が設けられた絶縁膜上面には、さらに第2スペーサ部を設けることができる。図1において、リッジ2aの右側に設けられた第2スペーサ部を符号5bで示し、リッジ2aの左側に設けられた第2スペーサ部を符号5b’で示す。以下では主として第2スペーサ部5bについて説明するが、第2スペーサ部5b’についても同様であることは言うまでもない。
図1において、リッジ2aの右側に設けられたブロック部を符号5cで示し、リッジ2aの左側に設けられたブロック部を符号5c’で示す。以下では主としてリッジ2aの右側に設けられたブロック部5cについて説明する。ただし、その説明はリッジ2aの左側に設けられたブロック部5c’についても当てはまることは言うまでもない。
尚、第1スペーサ部5a、第2スペーサ部5b及びブロック部5cが一体で形成されている場合、第1スペーサ部5aと第2スペーサ部5bとを連結する部分をブロック部5cとする。
パッド電極6は、共振器長方向における一直線上において少なくとも第1スペーサ部5aと絶縁膜4を被覆している。パッド電極6は第1スペーサ部5a上面の全面を被覆する必要はなく、少なくともその一部を被覆していればよい。図4に示すように第1スペーサ部5aを介して半導体部2上面に設けられたパッド電極6上面は、第1スペーサ部5aを介さずに半導体部2上面に設けられたパッド電極6上面よりも高くなっている。パッド電極6の材料としては、熱伝導率に優れた金属材料とすることができ、例えば、Ni、Ti、Au、Pt、Pd、Wの少なくとも一つを含めることができる。
半導体レーザ素子100と異なる形態として、図7に示す半導体レーザ素子200のような構成をとることもできる。半導体レーザ素子200は、絶縁膜4上に、スペーサ部50を有し、第2スペーサ部及びブロック部を備えない。さらに、スペーサ部50は端面近傍ではなくリッジ2aの延伸方向における中央部に設けてある。この構成では、ミラー成分の回り込み抑制による放熱性の向上及びブロック部によりリーク抑制の効果は期待できないものの、ジャンクションダウン実装時における半導体レーザ200の傾き防止及び放熱性については一定のレベルで期待できる。
先ず、n型GaNからなるウエハ状の基板1上に、SiドープAl0.02Ga0.98N(膜厚1.6μm)よりなる下地層と、SiドープIn0.05Ga0.95N(膜厚0.15μm)よりなるクラック防止層と、SiドープAl0.07Ga0.93N(膜厚0.9μm)よりなる下部クラッド層と、SiドープGaN(膜厚0.15μm)及びアンドープGaN(膜厚0.15μm)よりなる下部ガイド層と、MQWの活性層と、MgドープAl0.12Ga0.88N(膜厚1.5nm)及びMgドープAl0.16Ga0.84N(膜厚8.5nm)よりなるキャリア閉じ込め層と、ノンドープGaN(膜厚0.15μm)とMgドープGaN(膜厚0.35μm)よりなる上部ガイド層と、MgドープGaN(膜厚15nm)より上部コンタクト層と、を順に積層して半導体部2とした。なお、MQW活性層は、基板1側から順に、SiドープIn0.03Ga0.97N(膜厚170nm)よりなる障壁層と、アンドープIn0.14Ga0.86N(膜厚3nm)よりなる井戸層と、アンドープGaN(膜厚14nm)よりなる障壁層と、アンドープIn0.14Ga0.86N(膜厚3nm)よりなる井戸層と、アンドープIn0.03Ga0.97N(膜厚70nm)よりなる障壁層と、を備える。
ジャンクションダウン実装時、効果的に傾きを抑制するためには、リッジ2aの両側のほぼ全面に500nm厚さのSiO2を形成し、パッド電極6の表面全体を実質的に平坦にした構成も考えられる。しかしながら、そのように構成すると、上述したように放熱特性が悪化する。そのことを確認するために、比較例として、図11に示すように、リッジ2aの両側において、絶縁膜4,4’のほぼ全面に均一にSiO2を形成した半導体レーザ素子600を作製して放熱特性を実施例の半導体レーザ素子と比較した。すなわち、比較例の半導体レーザ素子600は、実施例の半導体レーザ素子において、外周を取り囲むように形成した第1スペーサ部5a,5a’、第2スペーサ部5b,5b’及びブロック部5c,5c’に代えて、リッジ2aの両側に絶縁膜4,4’のほぼ全面を覆うSiO2を形成した以外は半導体レーザ素子100と同様な構成を有する。
図8に過渡熱抵抗測定結果を示す。縦軸は熱抵抗値の相対値を示し、横軸は通電パルス時間を示している。チップとサブマウント間の熱抵抗値を示すと考えられるPT=0.01Secあたりの熱抵抗値に差があり、比較例よりも小さくなっていることが確認できた。この結果から、半導体レーザ素子100とサブマウント間の放熱性が比較例に比べて優れていることが理解できる。この熱抵抗の差は小さくみえるかもしれないが、Wクラスの高出力半導体レーザ素子を作成する場合、高電流領域において発熱量が大きくなるために、熱抵抗のわずかな差により発熱量に大きな差が生じてしまう。実際、このようなわずかな差であっても、後述するようにI-L特性やライフ特性に大きな差が生じることが理解できる。
実施例の放熱性が比較例よりも優れているためにこのような結果となったと考えられる。
以上のように、本発明に係る実施例の半導体レーザ素子100は、ジャンクションダウン接合時の傾きを抑制することができ、しかも放熱性の高いことが確認できた。
1…基板
2…半導体部
3…上部電極
4、4’…絶縁膜
5a、5a’…第1スペーサ部
5b、5b’…第2スペーサ部
5c、5c’…連結部
6…パッド電極
7…下部電極
8…支持部材
9…導電部材
Claims (7)
- 基板と、前記基板上に設けられ前記基板の反対側の面にリッジを有する半導体部と、前記リッジ上に設けられた電極と、前記リッジの両側の半導体部上に設けられた絶縁膜と、前記電極上に設けられたパッド電極と、を備え、前記パッド電極側を実装面側とする半導体レーザ素子であって、
前記パッド電極は、前記絶縁膜上に延在して設けられており、
前記半導体部と前記パッド電極の間の前記リッジから離れた一部にスペーサ部が設けられたことを特徴とする半導体レーザ素子。 - 前記スペーサ部は、前記半導体部の一方の端面近傍に配置された第1スペーサ部を含む請求項1記載の半導体レーザ素子。
- 前記スペーサ部は、前記半導体部の他方の端面近傍に配置された第2スペーサ部を含む請求項2に記載の半導体レーザ素子。
- 前記リッジに平行に前記基板の側面に沿って配置され、前記スペーサと実質的に同じ高さに形成されたブロック部を含む請求項3に記載の半導体レーザ素子。
- 前記第1スペーサ部と前記第2スペーサ部と前記ブロック部とが一体化されている請求項4記載の半導体レーザ素子。
- 前記スペーサ部は、絶縁材料からなる請求項1~5のうちのいずれか1つに記載の半導体レーザ素子。
- 前記リッジの上に位置するパッド電極の上面と、前記スペーサの上方に位置するパッド電極の上面とが実質的に同じ高さにある請求項1~6のうちのいずれか1つに記載の半導体レーザ素子。
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