JP2006108262A - Semiconductor laser element and its manufacturing method, semiconductor laser device, optical disk device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high reliability by suppressing the influence of residual stress applied to a semiconductor laser element in the semiconductor laser element of a ridge striped structure capable of low current operation with a low threshold current. <P>SOLUTION: Residual stress due to a difference between temperatures upon die bond processing and upon semiconductor laser element operation happens owing to a difference between thermal expansion coefficients of a heat sink and a semiconductor laser element 10. The residual stress is more increased as a size L of the semiconductor laser element 10 in the direction of the resonator length of the same is more increased. A substantially square die bonding surface is formed by making equal the length L of the semiconductor laser element 10 in the direction of the resonator of the same, and a length W2 of the element in the widthwise direction of the element. Consequently, the residual stress due to the difference between temperatures upon die bonding processing and upon semiconductor laser element operation happens isotropically and is uniformly applied to the element owing to stress dispersion action. Consequently, the occurrence of deterioration, chipping, and crack of the element due to stress concentration is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to, for example, a semiconductor laser element suitably used as a light source for reproducing an optical disk, a manufacturing method thereof, a semiconductor laser device using the semiconductor laser element, an optical disk apparatus using the semiconductor laser element, and a semiconductor laser element. It relates to the electronic equipment used.

  In recent years, with the miniaturization of optical disk devices, electronic devices equipped with portable optical disk devices have appeared, and semiconductor laser elements that consume less power even in high temperature environments have been demanded as light sources for reproduction.

  As this low power consumption semiconductor laser element, for example, a ridge buried type semiconductor laser element having a real guide structure as disclosed in Patent Document 1 is known. This is shown in FIG.

  FIG. 8 is a cross-sectional view showing a configuration example of a conventional ridge embedded semiconductor laser device having a real guide structure.

  As shown in FIG. 8, in the semiconductor laser device 100, a first cladding layer 102, an active layer 103, and a second cladding layer 104 are formed in this order on a semiconductor substrate 101. A flat surface and a ridge-shaped protrusion (ridge stripe portion) are present on the surface side of the second cladding layer 104, and the current blocking layer first region 105 and second region 106 are formed on the side surface of the ridge stripe portion. The current blocking layer third region 107 is formed on the flat surface of the second cladding layer 104. The current blocking layers 105 to 107 are made of a material having a refractive index smaller than that of the second cladding layer 104. A buffer layer 108 and a p-type cap layer 109 are formed on the ridge stripe portion, and an n-type cap layer 110 is formed on the current blocking layer third region 107. On top of that, a contact layer 111 is formed over the p-type cap layer 109 and the current blocking layers 106 and 107.

The current blocking layers 105 to 107 have a band gap larger than that of the active layer 103 and are almost transparent to the laser light, so that the waveguide loss is small and high-efficiency laser oscillation is possible with a low threshold.
JP 2002-50830 A

  In order to operate the low-threshold semiconductor laser device 100 having the real guide structure at a lower current, Joule heat generated in the vicinity of the active layer 103 is generated in order to prevent the temperature in the vicinity of the active layer 103 from increasing during operation. A heat dissipation structure that dissipates heat to the outside of the element 100 is required.

  For this reason, in Patent Document 1, the film thickness of the contact layer 111 provided above the ridge stripe portion is set as thin as about 3 μm. The thin contact layer 111 is bonded to a submount made of a high thermal conductivity material such as silicon carbide or aluminum nitride by a gold-tin brazing material or the like, and the heat generated in the active layer 103 is released to the outside via the submount. It was common to be used.

  However, in the conventional configuration described above, due to the difference in thermal expansion coefficient between the semiconductor laser element 100 and the heat sink (submount) bonded thereto, the bonding temperature of the gold-tin brazing material and the operating temperature of the semiconductor laser element 100 are Residual stress is generated due to this temperature difference, and since the contact layer 111 is thin, the residual layer is distorted by the residual stress, which causes the reliability of the semiconductor laser device 100 to be reduced.

  The present invention solves the above-mentioned conventional problems, and has a low threshold current, can be operated at a low current, can suppress the effect of residual stress applied to the element, and can obtain a high reliability. An object of the present invention is to provide a manufacturing method thereof, a semiconductor laser device using the same, an optical disk device using the same, and an electronic apparatus using the semiconductor laser element.

The semiconductor laser device of the present invention is a semiconductor laser device provided with a ridge stripe structure for allowing a current to flow intensively in a narrow region in parallel with a resonator direction for laser oscillation.
One of the element length in the resonator direction and the length in the element width direction orthogonal to the resonator direction is set within a range of plus / minus 10% of the other length. Achieved.

  Preferably, the element length in the resonator direction of the semiconductor laser element of the present invention is set equal to the length in the element width direction orthogonal to the resonator direction.

  Further preferably, each length in the cavity direction and the element width direction in the semiconductor laser device of the present invention is set within a range of 200 μm ± 20 μm.

  Further preferably, in the semiconductor laser device of the present invention, the thickness from the light emitting point to the outer surface closer to the light emitting point can be set smaller than the normal thickness.

  More preferably, the flatness of the outer surface near the light emitting point in the semiconductor laser device of the present invention is set to 0.1 μm or less in terms of Rmax value.

  Further preferably, the ridge stripe structure in the semiconductor laser device of the present invention is made of a high refractive index material, a ridge stripe portion serving as a current injection region, a refractive index lower than that of the ridge stripe portion, and a minority carrier. This is a real guide structure in which a current blocking region made of a semiconductor material having a polarity different from that of the ridge stripe portion is formed in the same plane.

  Further preferably, the width of the ridge stripe portion in the semiconductor laser device of the present invention is set to 1 μm or more and 3 μm or less.

  Further preferably, the directionality identification mark capable of distinguishing the position of the ridge stripe portion in the semiconductor laser device of the present invention and the direction of the emission end face on the side where the light output from the ridge stripe portion is higher is closer to the light emitting point. Is provided on at least one of the surface electrode side and the surface electrode side facing the surface electrode.

  Further preferably, a hologram pattern is formed on the surface electrode in the semiconductor laser device of the present invention, and the hologram pattern is irradiated on the surface of the device as a virtual image of the hologram pattern by irradiating the hologram pattern with reproduction coherent light from a specific external direction. The directionality identification mark that can identify the shape of the ridge stripe portion and the direction of the emission end face on the side where the light output from the ridge stripe portion is high can be reproduced.

  A semiconductor laser device manufacturing method according to the present invention is a semiconductor laser device manufacturing method for manufacturing the semiconductor laser device according to claim 5, wherein the surface irregularity shape measurement before processing, and the required processing amount based on the measurement result The plasma CVM (Chemical Vaporization Machining) method, which combines the calculation of (etching thickness) with the control of the processing position and processing amount, the flatness of the outer surface near the light emitting point is 0.1 μm in Rmax value. The following object is achieved by processing the following.

  A semiconductor laser device according to the present invention is such that the semiconductor laser element according to any one of claims 1 to 9 is die-bonded to a submount means made of a material having a good thermal conductivity and a thermal expansion coefficient equivalent to that of the semiconductor laser element. This achieves the above object.

  Preferably, the semiconductor laser element and the submount means in the semiconductor laser device of the present invention are made of a brazing material containing at least one of a gold-based material and a tin-based material on the surface electrode side closer to the light emitting point. Electrically joined.

  An optical disc apparatus according to the present invention is equipped with the semiconductor laser device according to claim 11 or 12 and reads or / and writes information from an optical disc, thereby achieving the object.

  An electronic apparatus according to the present invention is equipped with the semiconductor laser device according to claim 11 or 12, and reads or / and writes information from an optical disk, thereby achieving the object.

  The operation of the present invention will be described below with the above configuration.

  Residual stress due to a temperature difference between the die bonding process and the semiconductor laser element operation is generated due to a difference in thermal expansion coefficient between the heat sink and the semiconductor laser element. Therefore, when the width dimension is constant and the length of the active layer is longer than the width dimension, the residual stress increases as the length of the active layer increases, that is, as the dimension of the semiconductor laser element in the cavity length direction increases. Therefore, it is preferable to shorten the resonator length. Therefore, in the present invention, the length of the semiconductor laser element in the resonator direction is made equal to the length in the width direction, and the semiconductor laser element has a rectangular parallelepiped shape having a substantially square surface.

  If the length in the resonator direction is equal to the length in the element width direction on the surface where the semiconductor laser element is die-bonded, residual stress isotropically generated due to a temperature difference between the die bonding process and the semiconductor laser element operation. Due to the stress distribution action applied evenly to the element, deterioration of the element due to stress concentration, occurrence of cracks, cracks and the like are reduced and reliability is improved.

  Since the residual stress can be evenly distributed in this way, the active layer (light emitting point) that is easily affected by the stress can be brought close to the surface of the element (near the outer surface in the thickness direction). Therefore, Joule heat generated in the vicinity of the active layer can be radiated efficiently, and the temperature of the semiconductor laser element can be lowered.

  Compared with the conventional case, the active layer (light emitting point) of the semiconductor laser device is formed near the surface of the device, and the surface close to the light emitting point is the die bond side, and gold-tin brazing material is used, and the thermal conductivity is good. By die-bonding on a submount means (hereinafter simply referred to as submount) made of a material having a small difference from the thermal expansion coefficient of the semiconductor laser element, and fixing on the stem with a metal portion of the submount having good thermal conductivity. Thus, a packaged semiconductor laser device can be obtained.

  The external electrode for electrical joining of the semiconductor laser element has, for example, good storage stability, excellent ductility and malleability, and gold is formed on the surface in order to function as a buffer material for stress relaxation. Therefore, the thermal conductivity between the submount and the semiconductor laser element is good without generating unnecessary electrical conduction with the active layer formed in the vicinity of the die bond side surface by utilizing the alloying action of tin and gold. It is possible to form a simple bond.

  In the real guide structure, since the material property values of the ridge stripe portion and the current blocking region are slightly different, stress is easily generated in the ridge stripe formation portion even in the semiconductor laser element before die bonding. As in the present invention, by reducing the length in the resonator direction to be equal to the length in the element width direction, it is possible to emit light with high efficiency by the real guide structure while reducing instability of the transverse mode due to stress. .

  By setting the width of the ridge stripe part to 1 μm or more and 3 μm or less, a low-noise self-oscillation laser element can be obtained, and an increase in differential resistance that lowers the oscillation efficiency can be suppressed. When the width is smaller than 1 μm, the radiation characteristics are deteriorated.

  In the embedded type ridge stripe structure element, a step is generated on the surface in the vicinity of the ridge stripe portion due to the step difference from the flat portion of the ridge stripe portion, but the flatness of the outer surface near the light emitting point is 0. By setting the thickness to 1 μm or less, it is possible to reduce the impact received by the semiconductor laser element when it contacts the submount surface during die bonding of the semiconductor laser element. Furthermore, since there are few irregularities on the surface, the contact area between the brazing material before melting and the electrode of the semiconductor laser element increases, so that the wettability with the brazing material is improved.

  Surface profile near the light emitting point by plasma CVM (Chemical Vaporization Machining) method combining measurement of surface irregularities before processing, calculation of required processing amount based on measurement results, and control of processing position and processing amount Can be set to an Rmax value of 0.1 μm or less. The plasma CVM method is a method in which a gas having chemical reactivity with respect to a material to be processed is activated by a discharge plasma and processed, and mechanical damage due to the processing treatment is given in the same manner as the existing wet etching processing. There is no. Furthermore, since the discharge position and the processing time can be precisely controlled, it is possible to selectively process only the convex portion near the ridge stripe portion to be removed. Note that the plasma CVM is an ultra-precise machining method using a chemical reaction between a neutral radical having high reactivity in plasma and the surface of a workpiece. This processing method is chemical, and a geometrically excellent processed surface can be obtained in atomic units without impairing the original properties of the material.

  By flattening the surface in the vicinity of the ridge stripe part and eliminating the step, it becomes difficult to detect the position of the embedded ridge stripe part inside the element from the appearance, but by forming an identification mark on the element surface, It becomes possible to accurately position and mount the light emitting point with respect to the package.

  For example, by forming a hologram pattern on the surface electrode and irradiating coherent light for reproduction from a specific direction, the shape of the ridge stripe part and the light output from the ridge stripe part are high as a virtual image of the hologram pattern on the element surface It is possible to reproduce the directionality identification mark that can identify the direction of the emission end face on the side. In order to identify a virtual image by a hologram pattern, a fine pattern such as a ridge stripe is reproduced with high contrast and can be identified. Also, in handling work to grab the element surface, even if a part of the hologram pattern is lost due to a pickup collet, etc., the contrast is only lowered, and the position identification accuracy of the virtual image is less affected and stable die bond position control. Can be done.

  As described above, according to the present invention, in a semiconductor laser device having a ridge stripe structure with a low threshold current and a high light emission efficiency, the length in the cavity direction and the length in the device width direction are made substantially equal, and the die bond surface By making the substantially square, the influence of the stress applied to the semiconductor laser element can be suppressed, and a highly reliable semiconductor laser device can be obtained.

  In addition, by bringing the light emitting point that is easily affected by stress close to the surface of the device and efficiently dissipating the Joule heat generated near the active layer, the temperature of the semiconductor laser device can be lowered and low current operation is possible. To do.

  Furthermore, by reducing the length in the resonator direction to be equal to the length in the element width direction, it is possible to perform high-efficiency light emission by the real guide structure while reducing instability of the transverse mode due to stress.

  Furthermore, by setting the width of the ridge stripe portion to 1 μm or more and 3 μm or less, a low-noise self-oscillation laser element can be obtained, and an increase in differential resistance that lowers the oscillation efficiency can be suppressed. When the width is smaller than 1 μm, the radiation characteristics are deteriorated.

  Furthermore, by setting the flatness of the outer surface close to the light emitting point to 0.1 μm or less by Rmax, it is possible to reduce the impact (stress) received by the semiconductor laser element during die bonding and to wet the brazing material. The sex is also improved.

  Furthermore, by forming an identification mark on the element surface, the light emitting point can be positioned and mounted with high accuracy with respect to the package, and a semiconductor laser device with little variation in the light emitting point position can be obtained.

Embodiments 1 to 3 of the semiconductor laser element, the semiconductor laser device, and the optical disk device of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a perspective view showing a configuration example of a semiconductor laser element according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the semiconductor laser device 10 has a ridge stripe structure in which a ridge-shaped current path 14A extends in the length L direction, and an n-type GaAlAs first cladding layer 12 on an n-type GaAs substrate 11. The p-type GaAlAs active layer 13 and the p-type GaAlAs second cladding layer 14 are sequentially stacked in this order. On the upper surface of the second cladding layer 14, a central convex ridge stripe portion 14A and flat portions 14B on both sides are formed. The light emitting point (active layer 13) of the semiconductor laser element 10 is located in the vicinity of the outer surface of the die bond side in the thickness direction. Further, the width W1 of the ridge stripe portion 14A is set to 1 μm or more and 3 μm or less. When the width is smaller than 1 μm, the radiation characteristics are deteriorated.

  This semiconductor laser device 10 has a buried type real guide structure, and an n-type GaAlAs current blocking region 15 is provided on the flat portion 14B of the second cladding layer 14 so as to bury the ridge stripe portion 14A. Further, a p-type GaAs contact layer 16 is stacked over the ridge stripe portion 14A and the current blocking region 15. The flatness of the surface of the contact layer 16 which is the outer surface close to the light emitting point in the thickness direction is set to 0.1 μm or less in terms of the Rmax value. A die-bonding electrode 17 as a surface electrode made of an Au-based material is provided on the surface of the contact layer 16, and a wire-bonding electrode 18 as a surface electrode is formed on the back side of the substrate 11.

  The external shape of the semiconductor laser element 10 is set such that the length L in the resonator direction is substantially equal to the length W2 in the width direction orthogonal to the resonator direction. In the first embodiment, the semiconductor laser element 10 has a cavity length L of 200 μm ± 20 μm, a chip width W2 of 200 μm ± 20 μm and a substantially square surface, and the thickness t of the semiconductor laser element 10 is 65 μm ± 10 μm. And it has a rectangular parallelepiped shape. By forming this square surface as a die-bonding surface, the residual stress in the cavity direction and the chip width direction is uniformly applied to the semiconductor laser element 10.

  FIG. 2 is a graph showing the relationship between the resonator length L and the operating current value of the semiconductor laser device 10 of FIG. In FIG. 2, the vertical axis indicates the optical output Po, the horizontal axis indicates the forward current Iop, the thin line indicates the resonator length L is 180 μm, the thick line indicates the resonator length L is 200 μm, and the dotted line indicates the resonator length. It is a graph in case L is 250 micrometers.

  As shown in FIG. 2, when the resonator length L of the semiconductor laser element 10 is 250 μm → 200 μm, the reduction rate of the oscillation threshold is larger than the reduction rate of the resonator length, and the effect of strain equalization appears. ing. On the other hand, when the resonator length L is shortened from 200 μm to 180 μm, the rate of reduction of the resonator length and the rate of decrease of the oscillation threshold are substantially proportional, and the effect of strain equalization is not so much in this range. I understand. By setting the resonator length L within this range, it was possible to realize an infrared-emitting optical disk reproducing light source semiconductor laser device capable of driving at a low current and having an oscillation wavelength in the region of 770 nm to 806 nm.

  The reason why the oscillation threshold decreases approximately proportionally to the resonator length by equalizing the strain is considered to be because the band structure does not change due to the strain. As a result, no abnormality occurs in the polarization direction of the output laser light.

  However, if the resonator length L of the semiconductor laser element 10 is made too short, the reliability during a long-term energization operation tends to decrease. This is considered because the oscillation threshold current density is increased. Therefore, as in the first embodiment, the element size having the resonator length L of 200 μm and the chip width W2 of 200 μm is optimal. In addition, since the reduction of the element size decreases the workability, the element size of the first embodiment is also suitable in terms of production.

  Hereinafter, the manufacturing process of the semiconductor laser device 10 of the first embodiment will be described in detail with reference to FIGS. 3A and 3B.

  3A and 3B are cross-sectional views for explaining each manufacturing process of the semiconductor laser device 10 of FIG.

  First, as shown in FIG. 3A (a), an n-type GaAlAs first cladding layer 12, a p-type GaAlAs active layer 13 and a p-type GaAlAs second cladding layer 14 are formed on an n-type GaAs substrate 11 in this order by MOCVD (organic). Each is formed sequentially by metal vapor phase epitaxy.

Next, as shown in FIG. 3A (b), in order to leave the ridge stripe portion 14A in the second cladding layer 14, a stripe mask 19 made of SiO ₂ or the like having a line shape with a width of 3 μm to 4 μm is formed. Using the mask 19 as a mask, the second cladding layer 14 is processed by dry etching, and the shape of the ridge stripe portion 14A is adjusted by wet etching. At this time, since the width W1 of the ridge stripe portion 14A is narrower than the mask size, the ridge stripe portion 14A having a width W1 of 1 μm or more and 3 μm or less is finally formed.

  Subsequently, as shown in FIG. 3A (c), the n-type GaAlAs current blocking region 15 is embedded on the flat portion 14B of the second cladding layer 14 and the stripe mask 19 by embedding the side surface of the ridge stripe portion 14A. To form.

  Further, as shown in FIG. 3B (d), after removing the stripe mask 19, a layer 16A to be the p-type GaAs contact layer 16 is formed. Here, since a step in the order of μm remains in the ridge stripe portion 14A and the current blocking region 15, the vicinity of the ridge stripe portion 14A is also affected by the step on the surface side of the layer 16A on which the crystal is uniformly grown from above. The excitement remains.

  Therefore, in the first embodiment, as shown in FIG. 3B (d), the surface shape (surface unevenness shape) of the layer 16A is accurately measured, and the processing position and processing height (processing height) of the ridge stripe portion (convex portion) are processed. (Required amount) data. Plasma that selectively adjusts surface irregularities by dry etching using chemical reaction between neutral radicals generated by discharge and reactive surface in reactive gas atmosphere while numerically controlling local discharge position and processing amount Using the CVM method (Chemical Vaporization Machining), as shown in FIG. 3 (e), the flatness of the outer surface near the light emitting point is processed into an ultra-smooth flat surface 16B with an Rmax of 0.1 μm or less. A type GaAs contact layer 16 is formed.

  Thereafter, a die bond electrode 17 is formed on the surface close to the ridge stripe portion 14A, and a wire bond electrode 18 is formed on the back surface side of the n-type GaAs substrate 11. These electrodes 17 and 18 are both made of a gold-based metal material.

  In the first embodiment, the position of the ridge stripe portion 14A and the direction of the emission end surface on the side where the light output from the ridge stripe portion 14A is high (the high output side end surface is the interference color of the reflective film) Directional identification marks that can be identified as yellow to blue).

  As shown in FIG. 4, a hologram pattern 20 is formed on the wire bonding electrode 18. By irradiating a coherent plane wave as a hologram reproducing light 22 from a hologram reproducing light source 21 such as the semiconductor laser element 10 to the wire bonding electrode 18 at an angle, the wire bonding electrode 18 is 3 μm to 10 μm corresponding to the shape of the ridge stripe portion 14A. A ridge stripe hologram image 23 having a width is reproduced as a virtual image on the surface side of the semiconductor laser element 10. In the first embodiment, since the pattern measurement is performed by the CCD camera, the light source wavelength of the hologram reproduction light 22 uses an infrared laser light source so that the sensitivity of the CCD camera can be increased.

The direction identification mark is not limited to this as long as it can identify the position of the ridge stripe portion 14A and the direction of the emission end surface on the side where the light output from the ridge stripe portion 14A is high. As long as it is formed on at least one of the surface side closer to the surface and the surface side facing the surface.
(Embodiment 2)
FIG. 5 is a perspective view showing a configuration example of a semiconductor laser device using the semiconductor laser element 10 of FIG. 1 according to the second embodiment.

  As shown in FIG. 5, in the semiconductor laser device 30, the semiconductor laser element 10 is mounted on a submount 31, and the submount 31 is mounted on a metal stem 32. A metal cap 34 is welded to the stem 32 in order to protect the semiconductor laser element 10, the submount 31 and the light receiving element 33. A hologram element 35 on which a diffraction grating for guiding reflected light from the optical disk 1 described later in FIG. 7 to the light receiving element 33 is fixed to the opening surface of the cap 34 by a UV adhesive or the like.

  The semiconductor laser element 10 includes a submount 31 made of a material having good thermal conductivity and a difference in thermal expansion coefficient from the semiconductor laser element 10 in consideration of electric conductivity and thermal conductivity, and a side closer to the light emitting point. On the surface side, a solder material containing at least one of a gold-based material and a tin-based material is used, and the surface closer to the light emitting point is used as a die-bonding surface to be bonded electrically and mechanically.

  For example, as shown in FIG. 6, the submount 31 in which a brazing material 311 made of 70Au-30Sn containing Au at a ratio of 70 and Sn at a ratio of 30 is formed with a thickness of 3 μm is made of an Au-based material of the semiconductor laser device 10. The semiconductor laser element 10 and the submount 31 can be bonded together by die-bonding the die-bonding electrode 17 side, heating and melting the brazing material 311, and alloying with the die-bonding electrode 17 of the semiconductor laser element 10. In order to lower the processing temperature at this time, it is also possible to use a submount on which a Sn-3Ag-0.5Cu three-element brazing material is formed. The wire bonding electrode 18 of the semiconductor laser element 10 is wire-bonded to the electrode on the submount 31 by a gold wire or the like.

  As the submount 31, it is possible to use SiC-based ceramics or AlN-based ceramics having excellent thermal conductivity and insulating properties. In addition, in order to detect the light output from the semiconductor laser element 10 by receiving the light from the back surface opposite to the main emission surface with the monitor photodiode, the sub photodiode in which the monitor photodiode is formed using Si material is used. Sometimes a mount is used.

In other words, if a metal material is used as the submount, heat conduction is good, but the linear expansion coefficient differs from that of the semiconductor laser element by one digit or more, so that stress breakdown occurs. In addition, when a ceramic material is used as the submount, it does not lead to stress breakdown although its linear expansion coefficient is several times larger than that of the semiconductor material. When a semiconductor material such as Si material is used as the submount, the linear expansion coefficient is substantially equal to that of the semiconductor laser element, but the heat conduction is deteriorated.
(Embodiment 3)
FIG. 7 is a perspective view showing a configuration example of Embodiment 3 of the optical disk device on which the semiconductor laser device 30 of FIG. 5 is mounted.

  As shown in FIG. 7, in order to read information from the optical disc 1, the optical disc device 40 includes a semiconductor laser device 30 provided with a semiconductor laser element 10 serving as an emission light source, and light emitted from the semiconductor laser device 30. And an optical system 41 for condensing light on the surface.

  The optical system 41 includes a collimating lens 411 that converts light emitted from the semiconductor laser element 10 into parallel light rays, a rising mirror 412 that changes the direction of the parallel light rays from the collimating lens 411 toward the optical disc 1, And an objective lens 413 for condensing parallel rays from the rising mirror 412 on the surface of the optical disc 1.

  With the above configuration, the light emitted from the semiconductor laser element 10 is condensed on the surface of the optical disc 1 through the collimating lens 411, the rising mirror 412, and the objective lens 423. Information light including information reflected by the surface of the optical disk 1 returns to the hologram element 35 through the objective lens 413, the rising mirror 412, and the collimator lens 411, and is diffracted by the diffraction grating provided on the surface of the hologram element 35. Is incident on the light receiving element 33. The information light incident on the light receiving element 33 has different strengths depending on the information recorded on the surface of the optical disc 1, and is converted into an electric signal according to the strength of the information light by the light receiving element 33. Information recorded on the optical disc 1 is detected.

  As described above, according to the first to third embodiments, the length L2 in the resonator direction and the length W2 in the width direction are made substantially equal in the infrared light source that is optimal as the light source for reproduction of the optical disc apparatus 40. Thus, by making the die bond surface substantially square, the influence of stress applied to the semiconductor laser element 10 can be suppressed, and a highly reliable semiconductor laser device 30 using this can be obtained.

  In addition, since the effect of stress can be suppressed in the semiconductor laser device 10 having a low threshold current and high light emission efficiency due to the real guide structure, the light emitting point that is susceptible to the stress is brought close to the surface of the semiconductor laser device 10 to activate the semiconductor laser device 10. By efficiently dissipating the Joule heat generated in the vicinity of the layer, the temperature of the semiconductor laser element 10 can be lowered and a low current operation can be realized. Further, the semiconductor laser device 10 has a high efficiency by the real guide structure while reducing the instability of the transverse mode due to stress by reducing the length L in the resonator direction to be equal to the length W2 in the chip width direction. Light emission is possible.

  Furthermore, since the semiconductor laser element 10 has an element size that is easy to process in the production process, the productivity can be improved and a low-cost semiconductor laser device can be supplied.

  Furthermore, by setting the flatness of the outer surface near the light emitting point to 0.1 μm or less by Rmax, it is possible to reduce the impact (stress) received by the semiconductor laser device 10 during die bonding and The wettability can also be improved.

  In the semiconductor laser device 30, the light emitting point is several μm in size, and it is important to control the light emitting position so as not to vary with respect to the outer shape of the package. However, according to the second embodiment, the light emitting point is formed on the element surface. With the identification mark thus formed, the identification accuracy of the position of the ridge stripe portion can be improved at the time of die bonding of the semiconductor laser element 10, and the semiconductor laser device 30 with little variation in the light emitting point position can be obtained.

  The light emitted from the semiconductor laser device 10 of the present invention is particularly suitable as a reproduction light source for the optical disc apparatus 40. In addition, the semiconductor laser device 10 of the present invention that consumes less power is suitable as a light source for electronic devices such as portable electronic information devices equipped with a portable optical disk device due to the downsizing of the optical disk device 40.

In the first embodiment, the element length L in the resonator direction and the length W2 in the element width direction orthogonal to the resonator direction are set to be approximately equal to each other. When one of the element length L in the direction and the length W2 in the element width direction orthogonal to the resonator direction is set within a range of plus / minus 10% of the other length, it is significant for reliability. There was no difference. Also, no abnormality occurred in the polarization direction, and a low oscillation threshold was realized.

In the first embodiment, the case where the light emitting point is located near the outer surface in the thickness direction has been described. In short, the thickness from the light emitting point to the outer surface closer to the light emitting point is a normal thickness (the thickness of the conventional one). It is possible to set a smaller value.

  As mentioned above, although this invention has been illustrated using preferable Embodiment 1-3 of this invention, this invention should not be limited and limited to this Embodiment 1-3. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge from the description of specific preferred embodiments 1 to 3 of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  The present invention provides a ridge stripe structure having a low threshold current and a high light emission efficiency in the field of a semiconductor laser element suitably used as, for example, a light source for reproducing an optical disk, a manufacturing method thereof, and a semiconductor laser device using the semiconductor laser element. By making the length in the cavity direction and the length in the element width direction substantially equal to the semiconductor laser element, and making the die bond surface substantially square, the influence of stress applied to the semiconductor laser element is suppressed and reliability is improved. Semiconductor laser device having a high level, a semiconductor laser device using the same, and an optical disk device using the same can be obtained. The semiconductor laser device of the present invention can be suitably used in an optical disk device on which a semiconductor laser device is mounted as a light source with low power consumption, or an electronic apparatus using a portable optical disk device.

It is a perspective view which shows the structural example of the semiconductor laser element which concerns on Embodiment 1 of this invention. FIG. 2 is a graph for explaining electro-optical operation characteristics of the semiconductor laser device of FIG. 1 and showing a relationship between a resonator length and an operating current value. FIG. (A)-(c) is sectional drawing for demonstrating each manufacturing process (the 1) of the semiconductor laser element of FIG. (D)-(e) is sectional drawing for demonstrating each manufacturing process (the 2) of the semiconductor laser element of FIG. FIG. 2 is a perspective view for explaining a position identification mark of a ridge stripe portion provided in the semiconductor laser element of FIG. 1. It is a perspective view which shows the structural example of Embodiment 2 of the semiconductor laser apparatus using the semiconductor laser element of FIG. FIG. 2 is a perspective view for explaining die bonding to a submount of the semiconductor laser element of FIG. 1. FIG. 6 is a perspective view showing a configuration example of Embodiment 2 of an optical disk device using the semiconductor laser device of FIG. 5. It is sectional drawing which shows the structural example of the ridge embedding type | mold semiconductor laser element of the conventional real guide structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor laser element 11 Substrate 12 1st clad layer 13 Active layer 14 2nd clad layer 14A Ridge stripe part 14B Flat part 15 Current blocking area 16 Contact layer 17 Die-bonding electrode 18 Wire-bonding electrode 19 Stripe mask 20 Hologram pattern electrode 21 Hologram reproduction light source 22 Hologram reproduction light 23 Ridge stripe hologram image 30 Semiconductor laser device 31 Submount 311 Brazing material 32 Stem 33 Light receiving element 34 Cap 35 Hologram element 40 Optical disk device 41 Optical system 411 Collimating lens 412 Rising mirror 413 Objective lens

Claims (14)

In a semiconductor laser device provided with a ridge stripe structure for allowing a current to flow intensively in a narrow region in parallel to the resonator direction for laser oscillation,
A semiconductor laser element in which one of the element length in the resonator direction and the length in the element width direction orthogonal to the resonator direction is set within a range of plus or minus 10% of the other length.   2. The semiconductor laser device according to claim 1, wherein the element length in the resonator direction and the length in the element width direction orthogonal to the resonator direction are set to be equal.   2. The semiconductor laser device according to claim 1, wherein each length in the resonator direction and the element width direction is set within a range of 200 μm ± 20 μm.   The semiconductor laser device according to any one of claims 1 to 3, wherein a thickness from the light emitting point to the outer surface on the near side can be set smaller than a normal thickness.   5. The semiconductor laser device according to claim 4, wherein the flatness of the outer surface near the light emitting point is set to 0.1 μm or less in terms of an Rmax value.   The ridge stripe structure is made of a high refractive index material, a ridge stripe portion serving as a current injection region, and a semiconductor having a refractive index lower than that of the ridge stripe portion and having a minority carrier polarity different from that of the ridge stripe portion. 2. The semiconductor laser device according to claim 1, wherein the current blocking region made of a material has a real guide structure formed in the same plane.   The semiconductor laser device according to claim 6, wherein a width of the ridge stripe portion is set to 1 μm or more and 3 μm or less.   A direction identification mark that can identify the position of the ridge stripe portion and the direction of the emission end face on the side where the light output from the ridge stripe portion is high faces the surface electrode side closer to the light emitting point and the surface electrode. 8. The semiconductor laser device according to claim 6, wherein the semiconductor laser device is provided on at least one of the surface electrode sides.   A hologram pattern is formed on the surface electrode, and the hologram pattern is irradiated with reproduction coherent light from a specific external direction to form a virtual image of the hologram pattern on the element surface, and the shape of the ridge stripe portion and the ridge 9. The semiconductor laser device according to claim 8, wherein a directionality identification mark that can distinguish the direction of the emission end face on the side having a higher light output from the stripe portion is reproducible. A semiconductor laser device manufacturing method for manufacturing the semiconductor laser device according to claim 5, comprising:
The outer shape near the light emitting point is obtained by a plasma CVM (Chemical Vaporization Machining) method combining measurement of the surface irregularity shape before processing, calculation of the required processing amount based on the measurement result, and control of the processing position and processing amount. A method of manufacturing a semiconductor laser device, wherein the flatness of a surface is processed to an Rmax value of 0.1 μm or less.   10. A semiconductor laser device, wherein the semiconductor laser device according to claim 1 is die-bonded to submount means made of a material having good thermal conductivity and having a thermal expansion coefficient equivalent to that of the semiconductor laser device.   The semiconductor laser element and the submount means are electrically joined to each other on the surface electrode side closer to the light emitting point using a brazing material containing at least one of a gold-based material and a tin-based material. The semiconductor laser device described.   13. An optical disc apparatus that reads and / or writes information from or on an optical disc by mounting the semiconductor laser device according to claim 11 or 12.   13. An electronic device that reads and / or writes information from or on an optical disk by mounting the semiconductor laser device according to claim 11 or 12.