Method for testing semiconductor laser

Abstract

The invention relates to the technical field of lasers, and discloses a method for testing a semiconductor laser. Comprising the following steps: preparing a to-be-tested laser unit with the same current density as a target laser unit, wherein the power of the to-be-tested laser unit is smaller than that of the target laser unit; aging the to-be-tested laser unit; carrying out reliability test on the laser unit to be tested after the aging treatment; and on the premise that the reliability test result of the to-be-tested laser unit is qualified, obtaining a target laser unit with qualified reliability. According to the invention, a low-power to-be-tested laser unit is introduced for aging treatment and reliability test, and a reliability test conclusion of a high-power target laser unit is equivalently obtained; the low-power to-be-tested laser unit can be subjected to aging treatment and reliability test by using the existing machine table of a production line, so that the requirement on a driving power supply is reduced, equipment does not need to be newly added, energy can be saved, the manufacturing process is shortened, subsequent flow of unqualified products is avoided, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of lasers, and particularly relates to a test method for semiconductor lasers. Background Art

[0002] Due to advantages such as compact structure, long lifespan, high reliability, high electro-optical conversion efficiency, fast modulation rate, wide wavelength range, and easy integration, semiconductor lasers have been widely used in fields including industrial production, lidar, military offense and defense, optical communication, optical information storage, and medical beauty. With the development and progress of society, higher requirements have been put forward for the power, efficiency, and reliability of semiconductor lasers in many application fields. For example, in the industrial application of multi-kilowatt fiber lasers, for the 915nm / 976nm semiconductor lasers used for optical pumping, higher power and better reliability are required at the application end.

[0003] Currently, the pump sources of industrial ultra-high-power fiber lasers are usually semiconductor lasers in the 915nm / 976nm band with a power of 35W - 45W. Such devices generally use a chip size with a stripe width of 280μm - 320μm and a cavity length of 5mm - 6mm. To further reduce the chip usage to compress the system volume to obtain a higher power-to-mass ratio and reduce costs, the industry is developing and mass-producing semiconductor laser chips with a power of 55W and higher. Before the semiconductor lasers are shipped, it is necessary to screen out die with qualified reliability for package testing. However, the existing aging machines on the production line have the problem of too low drive current, which is not sufficient to verify the reliability of larger-sized and higher-power die and screen out qualified die; adding new machines will increase costs and result in low economic benefits. Summary of the Invention

[0004] In view of this, the present invention provides a test method for semiconductor lasers to solve the problem that the existing production line cannot achieve the performance detection of high-power semiconductor lasers.

[0005] In a first aspect, the present invention provides a test method for semiconductor lasers, which is applied to a semiconductor laser production line. The test method includes:

[0006] Preparing a laser unit under test with the same current density as the target laser unit, where the power of the laser unit under test is less than the power of the target laser unit;

[0007] Performing an aging treatment on the laser unit under test;

[0008] Performing a reliability test on the laser unit under test after the aging treatment;

[0009] On the premise that the reliability test result of the laser unit under test is qualified, obtaining a target laser unit with qualified reliability.

[0010] Beneficial effects: To obtain the reliability test results of the target laser unit with high power, a laser unit to be tested with lower power is introduced, and it is aged and reliability-tested, so as to obtain the conclusion that the target laser unit is reliable, that is, to obtain a reliable target laser unit. Compared with the target laser unit with high power, the laser unit to be tested with lower power can be aged and reliability-tested using existing machines, which reduces the requirements for the drive power supply and can complete the aging and screening work without new equipment, reducing the investment cost; in addition, it can also achieve the purpose of saving energy and shortening the process, avoiding the waste of packaging and testing production capacity, heat sink materials and labor costs caused by the backflow of unqualified products, and ultimately reducing the production cost.

[0011] In an optional implementation manner, preparing a laser unit to be tested with the same current density as the target laser unit includes:

[0012] Based on the relationship that the current density of the laser unit to be tested is equal to that of the target laser unit, the following relational expression is obtained: where I1 is the test current of the target laser unit, I2 is the test current of the laser unit to be tested, W1 is the ridge width of the target laser unit, W2 is the ridge width of the laser unit to be tested, L1 is the cavity length of the target laser unit, and L2 is the cavity length of the laser unit to be tested; the cavity length L2 of the laser unit to be tested is equal to the cavity length L1 of the target laser unit, and the ridge width W2 of the laser unit to be tested is less than the ridge width W1 of the target laser unit;

[0013] According to the known ridge width W1 of the target laser unit, the unit test current I1 of the target laser, and the cavity length L1 of the target laser unit, as well as the test current I1 of the laser unit to be tested, the cavity length L2 and the ridge width W2 of the laser unit to be tested are obtained;

[0014] According to the obtained cavity length L2 and ridge width W2 of the laser unit to be tested, the laser unit to be tested is prepared.

[0015] Beneficial effects: Set the cavity lengths and overall widths of the target laser unit and the laser unit under test to be equal, i.e., L1 and L2 are equal, and H1 and H2 are equal, so as to facilitate the cleavage of the laser unit. Based on the current density being equal to the magnitude of the test current divided by the current injection area, and the current injection area being equal to the product of the ridge width and the cavity length, where the ridge is a raised structure formed by etching on the epitaxial structure of the laser unit, so as to facilitate efficient current injection on this structure. Based on the equal current densities of the target laser unit and the laser unit under test with different powers, an equivalent relationship formula is obtained. According to the equivalent relationship formula, a laser unit under test with certain data can be designed and fabricated, equivalent to the reliability assessment intensity of the target laser unit, so that the development test and shipment of higher-power products can be completed without purchasing new machine tools, reducing the economic cost.

[0016] In an alternative embodiment, in the step of fabricating a laser unit under test with the same current density as the target laser unit, obtaining the cavity length L2 and the ridge width W2 of the laser unit under test includes:

[0017] Fabricate a first laser bar, where the first laser bar includes a target laser unit and a laser unit under test arranged along a first direction; the target laser unit and the laser unit under test are integrally formed, and the length of the target laser unit and the laser unit under test in a second direction is the cavity length, and the second direction is perpendicular to the first direction.

[0018] Beneficial effects: By first forming a strip-shaped first laser bar of the target laser unit and the laser unit under test, and then separately obtaining the target laser unit and the laser unit under test through cleavage, the present invention makes it convenient to perform surface coating on the opposite two side cavity surfaces along the first direction after forming the laser bar, so that the cavity surface coatings of each laser unit are consistent, improving the structural composition consistency of the laser unit under test and the target laser unit, thereby ensuring the accuracy of the equivalent aging treatment and reliability test results.

[0019] In an alternative embodiment, in the first laser bar, the number ratio range of the target laser unit to the laser unit under test is 1:1 to 5:1.

[0020] Beneficial effects: The present invention limits the number ratio range of the target laser unit to the laser unit under test to be 1:1 to 5:1, which can not only ensure the mass production of the target laser unit and improve the preparation efficiency of high-power semiconductor lasers; at the same time, it can also make the number of the laser unit under test structure meet the equivalent test requirements, improving the representativeness and accuracy of the sampling test.

[0021] In an alternative embodiment, in the first laser bar, the target laser unit and the laser unit under test are arranged alternately along the first direction.

[0022] Beneficial effects: In the first laser bar, the number of target laser units and the number of laser units to be tested are equal. One target laser unit, one laser unit to be tested, one target laser unit, one laser unit to be tested... are arranged alternately and repeatedly in this way, so that the laser units to be tested for random sampling and testing have a minimum structural error with the equivalent target laser units, which helps to improve the accuracy of the reliability test results of the laser units to be tested with low power by sampling and testing the equivalent target laser units with high power.

[0023] In an alternative embodiment, the first laser bar includes a target laser unit area and a laser unit to be tested area arranged along a first direction. The target laser unit area includes a plurality of target laser units arranged in sequence along the first direction, and the laser unit to be tested area includes a plurality of laser units to be tested arranged in sequence along the first direction.

[0024] Beneficial effects: The first laser bar is divided into two parts in the first direction. One part is the target laser unit area used to form a plurality of target laser units, and the other part is the laser unit to be tested area used to form a plurality of laser units to be tested, and the number of formed target laser units and laser units to be tested is equal. The way of concentrating on forming different laser units after such zoning can effectively improve the preparation efficiency of different laser units.

[0025] In an alternative embodiment, in the first laser bar, two target laser units and one laser unit to be tested are arranged alternately along the first direction.

[0026] Beneficial effects: In the first laser bar, the number ratio of target laser units to laser units to be tested is 2:1. Two target laser units, one laser unit to be tested, two target laser units, one laser unit to be tested... are arranged alternately and repeatedly in this way. It can not only make the laser units to be tested for random sampling detection have a small structural error with the equivalent target laser units, which helps to improve the accuracy of the reliability test results of the laser units to be tested with low power by sampling and testing the equivalent target laser units with high power; but also improve the preparation efficiency of the target laser units.

[0027] In an alternative embodiment, preparing the first laser bar includes:

[0028] Preparing a laser array, the laser array includes a plurality of laser bars arranged in sequence along a second direction and integrally formed, and at least one of the plurality of laser bars is the first laser bar;

[0029] Cleaving the laser array to form at least one first laser bar.

[0030] Beneficial effects: The laser array may be a case where it includes at least one first laser bar, and the other laser bars are all second laser bars of target laser units, so as to ensure the mass production of high-power target laser units. The laser array is cleaved and cut along the first cleavage groove and the second cleavage groove in the first direction to form a plurality of laser bars including the first laser bar; then, the front and rear cavity surfaces of the laser bars are coated with a film; finally, the laser bars are cleaved and cut along the first cleavage groove and the second cleavage groove in the second direction to form a plurality of semiconductor laser units including the target laser units and the laser units to be tested.

[0031] In an alternative embodiment, after preparing the laser units to be tested with the same current density as the target laser units and before aging the laser units to be tested, it further includes: performing a packaging process on the laser units to be tested; performing a packaging test on the laser units to be tested after the packaging process;

[0032] On the premise that the reliability test result of the laser unit to be tested is qualified and after obtaining the target laser unit with qualified reliability, it further includes: performing a packaging process on the target laser unit; performing a packaging test on the target laser unit after the packaging process.

[0033] Beneficial effects: Before aging the laser units to be tested, it further includes performing a packaging process and a packaging test on the laser units to be tested. The packaging process includes, for example, wire bonding, which is convenient for electrical injection. The packaging test screens out and removes the laser units to be tested damaged during the packaging process, achieving the first-step screening of the laser units to be tested, which helps to obtain stable-performing laser units to be tested for aging treatment. Similarly, after equivalently obtaining the target laser unit with qualified reliability, it is also necessary to perform a packaging process and a packaging test on the target laser unit in order to obtain a target laser unit with good performance.

[0034] In an alternative embodiment, aging the laser units to be tested includes: on the premise that the packaging test result of the laser units to be tested is qualified, performing a preliminary screening process on the laser units to be tested; aging the laser units to be tested after the preliminary screening process;

[0035] After performing a packaging test on the target laser unit after the packaging process, it further includes: on the premise that the packaging test result of the target laser unit is qualified, performing a preliminary screening process on the target laser unit; performing a performance test on the target laser unit after the preliminary screening process.

[0036] Beneficial effects: Aging the laser unit to be tested that has passed the packaging and testing specifically includes power-on preliminary screening treatment in a short period and long-term aging treatment. The preliminary screening treatment is also the initial aging by power-on, which is a process of eliminating early failures; then, long-term aging treatment is carried out to simulate the actual use situation of the laser unit to be tested, ensuring that the laser unit to be tested with stable performance is obtained, so as to provide a laser unit to be tested that meets the actual use situation for reliability testing. The preliminary screening treatment of the target laser unit with qualified packaging and testing results is carried out by power-on to test the stability of the target laser unit. Finally, performance tests are carried out on the target laser unit that has completed the preliminary screening treatment, such as the light-emitting effect, etc. Finally, the products with good and stable performance are warehoused, packaged, and shipped, and finally, high-power semiconductor lasers with stable performance are obtained in batches; if they are unqualified, they will be scrapped as a whole. Description of the Drawings

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a schematic flowchart of the test method for the semiconductor laser according to the embodiment of the present invention;

[0039] Figure 2 It is a schematic top view structure diagram of the target laser unit according to the embodiment of the present invention;

[0040] Figure 3 It is a schematic top view structure diagram of the laser unit to be tested according to the embodiment of the present invention;

[0041] Figure 4 It is a schematic structure diagram of the first type of first laser bar according to the embodiment of the present invention;

[0042] Figure 5 It is a schematic structure diagram of the second type of first laser bar according to the embodiment of the present invention;

[0043] Figure 6 It is a schematic structure diagram of the third type of first laser bar according to the embodiment of the present invention;

[0044] Figure 7 It is a schematic structure diagram of the laser array according to the embodiment of the present invention.

[0045] Description of the reference numerals:

[0046] 100, laser array; 101, first laser bar; 102, second laser bar;

[0047] 1. Target laser unit; 11. First front electrode; 12. First positioning structure; 13. First groove; 14. First current injection window; 15. First cleavage groove;

[0048] 2. Laser unit to be measured; 21. Second front electrode; 22. Second positioning structure; 23. Second groove; 24. Second current injection window; 25. Second cleavage groove; 26. Marking structure. Detailed implementation mode

[0049] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the convenience of description, only parts related to the present invention rather than all structures are shown in the drawings. In the following description, the description of well-known structures and technologies is omitted to avoid unnecessarily confusing the concept of the present invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the drawings. These figures are not drawn to scale, and for the purpose of clear expression, some details are enlarged, and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs. In the context of the present invention, when a layer / component is referred to as being "on" another layer / component, the layer / component can be directly on the other layer / component, or there can be an intermediate layer / component between them. In addition, if a layer / component is "on" another layer / component in one orientation, then when the orientation is reversed, the layer / component can be "under" the other layer / component.

[0050] In the related field of semiconductor lasers, the pump source of industrial ultra-high-power fiber lasers is usually a semiconductor laser in the 915nm / 976nm band with a power of 35W - 45W. To further reduce the chip usage to compress the system volume, obtain a higher power-to-mass ratio, and reduce costs, the industry is developing and mass-producing semiconductor laser chips with a power of 55W and higher. It should be noted that before the semiconductor lasers are shipped, it is necessary to screen out die with qualified reliability for packaging and testing. However, the existing aging machines on the production line have the problem of too low drive current, which is not sufficient to verify the reliability of larger-sized and higher-power die and screen out qualified die. Adding new machines will increase costs and result in low economic benefits. Therefore, how to perform reliability tests on semiconductor lasers with higher power without increasing economic costs is an urgent problem to be solved.

[0051] Based on this, refer toFigures 1 to 7 , this embodiment provides a test method for semiconductor lasers, which is applied to a semiconductor laser production line. Figure 1 As shown in the flowchart of this test method, the test method includes the following steps:

[0052] Step S101: Obtain a laser unit under test 2 with the same current density as the target laser unit 1, and the power of the laser unit under test 2 is less than that of the target laser unit 1.

[0053] In this embodiment, in order to obtain the reliability test results of the high-power target laser unit 1 (i.e., P-Die), a laser unit under test 2 with a smaller power (i.e., Q-Die) is introduced in this embodiment. For example, the laser unit under test 2 has the same cavity length and structural composition as the target laser unit 1, and only the ridge width is smaller than that of the target laser unit 1, that is, the power of the laser unit under test 2 is less than that of the target laser unit 1. Such a laser unit under test 2 can ensure the accuracy of the equivalent reliability test based on the equal current density with the target laser unit 1 under the condition of ensuring a single variable, that is, different powers, and is helpful for preparing the target laser unit 1 and the laser unit under test 2 in the same manufacturing process, and ensuring the reliability of the conclusion that the target laser unit 1 is qualified if the laser unit under test 2 is qualified.

[0054] In this embodiment, both the target laser unit 1 and the laser unit under test 2 are edge-emitting semiconductor laser units, which are prepared by production equipment on the semiconductor laser production line.

[0055] Step S102: Perform aging treatment on the laser unit under test 2.

[0056] On the existing aging machine, power on the prepared laser unit under test 2 with the same current density as the target laser unit 1 for aging treatment, simulating the conditions of the laser unit under test 2 in actual use to ensure the structural stability and performance reliability of the laser unit under test 2.

[0057] Step S103: Perform a reliability test on the laser unit under test after aging treatment.

[0058] Exemplarily, take the laser unit under test that has undergone long-term aging treatment off the aging machine, and then transfer it to the test machine for a short-term reliability test at, for example, a current of 40 A and a room temperature of 25 °C.

[0059] Step S104: Obtain a reliable target laser unit 1 on the premise that the reliability test result of the laser unit under test 2 is qualified.

[0060] If the reliability test result of the laser unit under test after aging treatment is qualified, it is equivalently concluded that the target laser unit with the same current density is equally reliable; then the qualified target laser unit 1 can be packaged and shipped. If the reliability test result of the laser unit under test 2 is unqualified, all the target laser units 1 and the laser units under test 2 prepared in the same batch will be scrapped.

[0061] To obtain the reliability test result of the target laser unit 1, a laser unit under test 2 is introduced for reliability testing, so as to obtain the conclusion that the reliability test of the target laser unit 1 is qualified.

[0062] In this embodiment, based on the principle that the current densities of the laser units under test 2 with different powers are equal to that of the target laser unit 1, in order to obtain the reliability test result of the high-power target laser unit 1, a laser unit under test 2 with a lower power is introduced for aging treatment and reliability testing. On the premise that the reliability test result of the laser unit under test is qualified, it is concluded that the reliability of the target laser unit 1 is also qualified. Compared with the target laser unit 1 with a higher power, the laser unit under test 2 with a lower power can be aged and reliability-tested using existing machines, which reduces the requirements for the drive power supply, and the aging and screening work can be completed without adding new equipment, achieving the purpose of saving energy and reducing the manufacturing process. It can also avoid the waste of packaging and testing production capacity, heat sink materials and labor costs caused by the backflow of unqualified products, and finally reduce the production cost.

[0063] Reference Figure 1 and Figure 2 , step S101 of preparing the laser unit under test 2 with the same current density as the target laser unit 1 includes:

[0064] Step S1011, based on the relationship that the current densities of the laser unit under test 2 and the target laser unit 1 are equal, obtain the relational expression: where I1 is the test current of the target laser unit 1, I2 is the test current of the laser unit under test 2, W1 is the ridge width of the target laser unit 1, W2 is the ridge width of the laser unit under test 2, L1 is the cavity length of the target laser unit 1, and L2 is the cavity length of the laser unit under test 2; the cavity length L2 of the laser unit under test 2 is equal to the cavity length L1 of the target laser unit 1, and the ridge width W2 of the laser unit under test 2 is less than the ridge width W1 of the target laser unit 1.

[0065] Reference Figure 2 and Figure 3, the cavity lengths and overall widths of the target laser unit 1 and the laser unit under test 2 are set to be equal, that is, L1 and L2 are equal, and H1 and H2 are equal, so as to facilitate the cleavage of the laser unit. Based on the current density being equal to the magnitude of the test current divided by the current injection area, and the current injection area being equal to the product of the ridge width and the cavity length, the ridge is a raised structure formed by etching on the epitaxial structure of the laser unit, so as to facilitate efficient current injection on this structure. Based on the equal current densities of the target laser unit 1 and the laser unit under test 2 with different powers, the above equivalent relationship is obtained. Figure 2 and Figure 3 The arrow shown in Figure 3 indicates the emission direction of the laser.

[0066] Step S1012, according to the known ridge width W1 of the target laser unit 1, the unit test current I1 of the target laser, and the cavity length L1 of the target laser unit 1, as well as the test current I1 of the laser unit under test 2, obtain the cavity length L2 and the ridge width W2 of the laser unit under test 2.

[0067] Exemplarily, in this embodiment, the ridge width W1 of the target laser unit 1 with higher power is set to 400 μm, and the test current required for its reliability assessment is 50 A; the current upper limit of the existing aging machine equipment in the production line is 40 A. When L1 = L2, through the control unit and calculation unit of the processing equipment, the ridge width W2 of the laser unit under test 2 is obtained as W2 = 40 / 50 × 400 = 320 μm. Therefore, designing the laser unit under test 2 with the above data can be equivalent to the aging treatment and reliability assessment intensity of the target laser unit 1, thus eliminating the need to newly purchase the machine equipment for the development and shipment of corresponding higher-power products, and reducing the economic cost.

[0068] Step S1013, prepare the laser unit under test according to the obtained cavity length L2 and ridge width W2 of the laser unit under test 2.

[0069] Exemplarily, the laser unit under test 2 is prepared through the control unit and processing unit of the processing equipment, such as through specific process steps such as deposition, exposure, and etching.

[0070] In one embodiment, referring to Figure 2 , the specific preparation steps of the above target laser unit 1 include:

[0071] Step S201, provide a first substrate layer.

[0072] Specifically, the first substrate layer provides physical support for the first epitaxial structure of the target laser unit 1 and is the basis for the growth of subsequent layers. A suitable substrate can enable the epitaxial layers to better maintain the crystal integrity and consistency during the growth process and reduce the generation of defects. Exemplarily, the material of the first substrate layer can be gallium arsenide (GaAs), indium phosphide (InP), etc.

[0073] Step S202: Grow a first buffer layer, a first lower confinement layer, a first lower waveguide layer, a first quantum well active layer, a first upper waveguide layer, a first upper confinement layer, and a first ohmic contact layer in sequence on one side surface of the first substrate layer to form a first epitaxial structure.

[0074] Exemplarily, the first buffer layer, the first lower confinement layer, the first lower waveguide layer, the first quantum well active layer, the first upper waveguide layer, the first upper confinement layer, and the first ohmic contact layer can be grown in sequence on one side surface of the first substrate layer by molecular beam epitaxy or chemical vapor deposition.

[0075] Specifically, the first buffer layer is used to relieve the lattice mismatch stress between the first substrate layer and the subsequent growth layers. The confinement layers (the first upper confinement layer and the first lower confinement layer) are used to confine the optical field in the waveguide layer to prevent the optical field from expanding into the highly doped confinement layer, causing free carrier absorption loss and reducing the efficiency of the target laser unit 1. At the same time, the highly doped confinement layer can reduce the series resistance of the target laser unit 1 and improve the electro-optical conversion efficiency.

[0076] The first quantum well active layer is the core region where laser is generated in the target laser unit 1. In the quantum well structure, carriers (electrons and holes) are confined in a very thin space to form a discrete energy level structure. When an injection current is applied, electrons and holes recombine in the quantum well, releasing photons to achieve the stimulated emission process and generate laser.

[0077] The refractive index of the waveguide layers (the first upper waveguide layer and the first lower waveguide layer) is between that of the confinement layer and the first quantum well active layer. An optical waveguide structure is formed through the refractive index difference to confine the optical field generated by the first quantum well active layer within a certain region for propagation, reduce light scattering and loss, improve the light propagation efficiency, ensure that the laser can be transmitted along a specific direction, and maintain good beam quality during the propagation process.

[0078] The first ohmic contact layer is used to provide a low-resistance ohmic contact between the target laser unit 1 and the external circuit, ensure that current can be smoothly injected into the device, and at the same time enable the device to be effectively electrically connected to the external circuit.

[0079] Step S203: Etch the surface of the first ohmic contact layer to form a raised first positioning structure 12.

[0080] The convex first positioning structure 12 facilitates positioning and etching in subsequent processes to improve positioning accuracy.

[0081] Step S204: Etch the first epitaxial structure on the first positioning structure 12 to form a set of first trenches 13 arranged at intervals in the first direction. The first trenches 13 penetrate the first ohmic contact layer, the first upper confinement layer, the first upper waveguide layer, the first quantum well active layer, the first lower waveguide layer, and part of the first lower confinement layer. A first ridge of the target laser unit 1 is formed between the set of first trenches 13.

[0082] That is, the ridge width of the target laser unit 1 is: the width in the first direction of the first ridge between the set of first trenches 13 within the first positioning structure 12. The first direction is Figure 2 the vertical direction shown.

[0083] Step S205: Form a first insulating layer on the first positioning structure 12. The first insulating layer has a first current injection window 14 that exposes part of the surface of the first ridge.

[0084] The first current injection window 14 helps the current to be injected more precisely, improving the current injection efficiency of the target laser unit 1.

[0085] Step S206: Grow a conductive material on the surface of the first substrate layer away from the first buffer layer to form a first back electrode.

[0086] Exemplarily, the conductive material can be gold (Au), germanium (Ge), nickel (Ni), and their alloys, etc. The first back electrode is an N-side electrode.

[0087] Step S207: Grow a conductive material on the first current injection window 14 to form a first front electrode, thereby fabricating the target laser unit 1.

[0088] The material of the first front electrode can be materials such as titanium (Ti), platinum (Pt), gold (Au), and their alloys. The first front electrode is a P-side electrode.

[0089] In addition, the first front electrode of the target laser unit 1 also has a first cleavage groove 15 at the edge position to facilitate cleavage and positioning of the laser array 100.

[0090] In one embodiment, refer to Figure 3, the specific preparation steps for forming the above-mentioned laser unit 2 to be measured are the same as those for the preparation of the target laser unit 1. The laser unit 2 to be measured has a second substrate layer, and a second buffer layer, a second lower confinement layer, a second lower waveguide layer, a second quantum well active layer, a second upper waveguide layer, a second upper confinement layer, and a second ohmic contact layer that are sequentially grown on one side surface of the second substrate layer, forming a second epitaxial structure. The layer structures of the laser unit 2 to be measured and the target laser unit 1 use the same materials and preparation processes. The edge position of the second front electrode of the laser unit 2 to be measured also has a second cleavage groove 25.

[0091] The difference between the laser unit 2 to be measured and the target laser unit 1 is as follows: First, in the first direction, the width of the second positioning structure 22 of the laser unit 2 to be measured is smaller than the width of the first positioning structure 12 of the target laser unit 1. Therefore, the distance between a group of second grooves 23 of the laser unit 2 to be measured, that is, the width of the second ridge in the first direction, is smaller than the width of the first ridge of the target laser unit 1, and the width of the second current injection window 24 is smaller than the width of the first current injection window 14. Second, a marking structure 26 is etched on the second front electrode of the laser unit 2 to be measured, such as forming a notch, so as to facilitate the distinction between the laser unit 2 to be measured and the target laser unit 1.

[0092] It should be understood that in the target laser unit 1, the area except for the first current injection window 14 and the first cleavage groove 15 should be covered by the first front electrode 11. However, for the convenience of showing the width of the first ridge and structures such as the first positioning structure 12 and the first groove 13, and due to the existence of the previous lithography path, Figure 2 In the top view schematic diagram of the target laser unit 2 shown, the first front electrode 11 is not fully shown.

[0093] Similarly, in the laser unit 2 to be measured, the area except for the second current injection window 24, the second cleavage groove 25, and the marking structure 26 should be covered by the second front electrode 21. However, for the convenience of showing the width of the second ridge and structures such as the second positioning structure 22 and the second groove 23, and due to the existence of the previous lithography path, Figure 3 In the top view schematic diagram of the laser unit 2 to be measured shown, the second front electrode 21 is also not fully shown.

[0094] In one embodiment, in step S101 of preparing the laser unit 2 to be measured with the same current density as the target laser unit 1, according to the obtained cavity length L2 and ridge width W2 of the laser unit 2 to be measured, step S1012 of preparing the laser unit 2 to be measured includes:

[0095] Prepare the first laser bar 101 (i.e., Q-Bar). The first laser bar 101 includes a target laser unit 1 and a laser unit to be measured 2 arranged along a first direction. The target laser unit 1 and the laser unit to be measured 2 are integrally formed, and the lengths of the target laser unit 1 and the laser unit to be measured 2 in a second direction are cavity lengths, and the second direction is perpendicular to the first direction.

[0096] According to the determined structures of the laser unit 2 to be measured and the target laser unit 1 obtained, such as the ridge width values of the laser unit 2 to be measured and the target laser unit 1, the cavity length value along the second direction, and the overall width value along the first direction, form the target laser unit 1 and the laser unit 2 to be measured on the same laser bar. For example, form an epitaxial structure with each structural layer on a substrate layer to form a strip-shaped laser bar, and then form the first laser bar 101 with the target laser unit 1 and the laser unit 2 to be measured through etching treatment. See Figures 4 to 6 , where the vertical direction in the figure is the first direction and the horizontal direction is the second direction. In this way, by first forming the strip-shaped first laser bar 101 of the target laser unit 1 and the laser unit 2 to be measured, and then obtaining the target laser unit 1 and the laser unit 2 to be measured through cleavage respectively, it is convenient to perform surface coating on the cavity surfaces on the opposite sides along the first direction after forming the laser bar, so that the cavity film layers of each laser unit are consistent, improving the structural composition consistency of the laser unit 2 to be measured and the target laser unit 1, and thus ensuring the accuracy of the equivalent aging treatment and the reliability test results.

[0097] In one embodiment, in the above-mentioned first laser bar 101, the quantity ratio range of the target laser unit 1 to the laser unit 2 to be measured is 1:1 to 5:1.

[0098] Within this range, it can not only ensure the mass production of the target laser unit 1 and improve the preparation efficiency of high-power semiconductor lasers, but also enable the quantity of the laser structure to be measured to meet the equivalent test requirements, improving the representativeness and accuracy of the sampling aging treatment and the reliability test.

[0099] As an optional implementation manner, in the above-mentioned first laser bar 101, the target laser unit 1 and the laser unit 2 to be measured are alternately arranged along the first direction.

[0100] Such as Figure 4As shown, that is, in the first laser bar 101, the number of target laser units 1 and the number of laser units 2 to be measured are equal. One target laser unit 1, one laser unit 2 to be measured, one target laser unit 1, one laser unit 2 to be measured... are arranged alternately and repeatedly in this way. Such an arrangement makes the structural error between the laser units 2 to be measured for random sampling and testing and the equivalent target laser units 1 to be minimized, which helps to improve the accuracy of the reliability test results of the laser units 2 to be measured with low power by sampling and the equivalent target laser units 1 with high power.

[0101] As another alternative implementation, the first laser bar 101 includes a target laser unit 1 area and a laser unit 2 area to be measured arranged along the first direction. The target laser unit 1 area includes a plurality of target laser units 1 arranged in sequence along the first direction, and the laser unit 2 area to be measured includes a plurality of laser units 2 to be measured arranged in sequence along the first direction.

[0102] As Figure 5 shown, the first laser bar 101 is divided into two equal upper and lower parts in the first direction. The upper part is the target laser unit area for forming a plurality of target laser units 1, and the lower part is the laser unit area to be measured for forming a plurality of laser units 2 to be measured. The number of formed target laser units 1 and laser units 2 to be measured is equal. Such a way of centrally forming different laser units after zoning can effectively improve the preparation efficiency of different laser units.

[0103] As yet another alternative implementation, in the first laser bar 101, two target laser units 1 and one laser unit 2 to be measured are arranged alternately along the first direction.

[0104] As Figure 6 shown, that is, in the first laser bar 101, the number ratio of the target laser units 1 to the laser units 2 to be measured is 2:1. Two target laser units 1, one laser unit 2 to be measured, two target laser units 1, one laser unit 2 to be measured... are arranged alternately and repeatedly in this way. Such an arrangement can not only make the structural error between the laser units 2 to be measured for random sampling and testing and the equivalent target laser units 1 to be relatively small, which helps to improve the accuracy of the reliability test results of the laser units 2 to be measured with low power by sampling and the equivalent target laser units 1 with high power, but also improve the preparation efficiency of the target laser units 1.

[0105] Of course, other arrangements are not excluded, such as three target laser units 1 or four target laser units 1 or five target laser units 1 arranged alternately with one laser unit 2 to be measured.

[0106] Based on the above solution, the steps of fabricating the first laser bar 101 include:

[0107] Fabricate a laser array 100, which includes a plurality of laser bars arranged in sequence along a second direction and integrally formed, and at least one of the plurality of laser bars is a first laser bar 101.

[0108] In one embodiment, an epitaxial structure is formed by epitaxially growing each structural layer on a wafer substrate layer in sequence to finally form a semiconductor laser substrate, and the semiconductor laser substrate has a plurality of laser arrays 100 densely arranged. Specifically, the laser array 100 includes a plurality of laser bars arranged in sequence along the second direction. Among these laser bars, at least one first laser bar 101 (i.e., Q-Bar) that simultaneously has a target laser unit 1 and a laser unit to be measured 2. Specifically, in this embodiment, as Figure 7 shown in a partial region of the semiconductor laser substrate, this region is a layout schematic diagram of a laser array 100 (i.e., Zone) including a first laser bar 101 and a second laser bar 102. The laser array 100 includes one first laser bar 101 (i.e., Q-Bar), and the other laser bars are all second laser bars 102 (i.e., P-Bar) that only include the target laser unit 1, ensuring the batch fabrication of high-power target laser units 1; and the first laser bar 101 is relatively arranged at the middle position of the laser array 100 to ensure the accuracy of the equivalent reliability test.

[0109] Cleave the laser array 100 to form at least one first laser bar 101.

[0110] Place the laser array 100 in a cleaving machine or a dicing machine, and cleave and cut the laser array 100 along a first cleavage groove 15 and a second cleavage groove 25 in a first direction to form a plurality of laser bars including the first laser bar 101; then coat the front and rear cavity surfaces of the laser bars; finally, cleave and cut the laser bars along the first cleavage groove 15 and the second cleavage groove 25 in the second direction to form a plurality of semiconductor laser units including the target laser unit 1 and the laser unit to be measured 2.

[0111] The above steps such as cleaving are applicable to each laser array 100 of the semiconductor laser substrate to batch obtain semiconductor laser units, and finally batch obtain semiconductor laser devices through packaging and the like.

[0112] In one embodiment, after step S101 of preparing the laser unit under test 2 with the same current density as the target laser unit 1, and before step S102 of aging the laser unit under test 2, the following steps are further included: performing a packaging process on the laser unit under test 2; performing a packaging test on the laser unit under test 2 after the packaging process.

[0113] Specifically, before aging the laser unit under test 2, the following steps are further included: performing a packaging process and a packaging test on the laser unit under test 2. The packaging process includes, for example, wire bonding, etc., which is convenient for electrical injection; the packaging test screens out and removes the laser units under test 2 damaged during the packaging process, achieving the first-step screening of the laser units under test 2, which helps to obtain laser units under test 2 with stable performance for aging.

[0114] In addition, on the premise that the reliability test result of the laser unit under test 2 is qualified, after step S104 of obtaining the target laser unit 1 with qualified reliability, the following steps are further included: performing a packaging process on the target laser unit 1; performing a packaging test on the target laser unit 1 after the packaging process.

[0115] After equivalently obtaining the target laser unit 1 with qualified reliability, a packaging process and a packaging test are also required for the target laser unit 1 in order to obtain a target laser unit with good performance.

[0116] Based on the above solution, step S102 of aging the laser unit under test 2 includes: on the premise that the packaging test result of the laser unit under test 2 is qualified, performing a preliminary screening process on the laser unit under test 2; aging the laser unit under test 2 after the preliminary screening process.

[0117] That is to say, aging the laser unit under test 2 with qualified packaging test on the existing aging machine specifically includes: a power-on preliminary screening process in a short time and an aging process in a long time. The preliminary screening process is also the initial aging by power-on, a process of eliminating early-failure products. For example, short-term aging is performed under the conditions of a current of 40 A, a temperature of 30 °C, and a time of 50 hr to eliminate the laser units under test 2 with obvious defects. Then, an aging process in a long time is performed. For example, under the conditions of a current of 40 A, a temperature of 30 °C, and a time of 500 hr, the actual use situation of the laser unit under test 2 is simulated to ensure that a laser unit under test 2 with stable performance is obtained, so as to provide a laser unit under test 2 that meets the actual use situation for reliability testing.

[0118] In addition, after the packaged target laser unit 1 is subjected to packaging tests, it further includes: on the premise that the packaging test results of the target laser unit 1 are qualified, performing preliminary screening on the target laser unit 1; and performing performance tests on the target laser unit 1 after preliminary screening.

[0119] The preliminary screening of the target laser unit 1 with qualified packaging test results is also carried out by applying power to test the stability of the target laser unit 1. Finally, performance tests are performed on the target laser unit 1 after preliminary screening, such as the light-emitting effect, etc. Finally, the products with good and stable performance are warehoused, packaged, and shipped, and finally high-power semiconductor lasers with stable performance are obtained in batches; if they are unqualified, they will be scrapped as a whole.

[0120] In the above description, no detailed explanations are made for the technical details such as the composition and etching of each layer. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of the required shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not exactly the same as the methods described above. In addition, although the above embodiments are described separately, this does not mean that the measures in each embodiment cannot be used advantageously in combination.

[0121] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A testing method for a semiconductor laser, characterized in that, Applied to a semiconductor laser production line, the test method includes: Preparing a laser unit under test with the same current density as the target laser unit, where the power of the laser unit under test is less than the power of the target laser unit; Performing an aging treatment on the laser unit under test; Performing a reliability test on the laser unit under test after the aging treatment; On the premise that the reliability test result of the laser unit under test is qualified, obtaining a target laser unit with qualified reliability.

2. The test method of the semiconductor laser according to claim 1, characterized in that The step of preparing a laser unit under test with the same current density as the target laser unit includes: Based on the relationship that the current densities of the laser unit to be measured and the target laser unit are equal, the following relational expression is obtained: Wherein, I1 is the test current of the target laser unit, I2 is the test current of the laser unit to be measured, W1 is the ridge width of the target laser unit, W2 is the ridge width of the laser unit to be measured, L1 is the cavity length of the target laser unit, and L2 is the cavity length of the laser unit to be measured; the cavity length L2 of the laser unit to be measured is equal to the cavity length L1 of the target laser unit, and the ridge width W2 of the laser unit to be measured is less than the ridge width W1 of the target laser unit; According to the known ridge width W1 of the target laser unit, the unit test current I1 of the target laser, and the cavity length L1 of the target laser unit, as well as the test current I1 of the laser unit under test, obtaining the cavity length L2 and ridge width W2 of the laser unit under test; Preparing the laser unit under test according to the obtained cavity length L2 and ridge width W2 of the laser unit under test.

3. The test method of the semiconductor laser according to claim 2, characterized in that, In the step of preparing a laser unit under test with the same current density as the target laser unit, the obtaining of the cavity length L2 and ridge width W2 of the laser unit under test includes: Preparing a first laser bar, where the first laser bar includes the target laser unit and the laser unit under test arranged along a first direction; the target laser unit and the laser unit under test are integrally formed, and the length of the target laser unit and the laser unit under test in a second direction is the cavity length, and the second direction is perpendicular to the first direction.

4. The test method of the semiconductor laser according to claim 3, characterized in that, In the first laser bar, the quantity ratio range of the target laser unit to the laser unit under test is 1:1 to 5:

1.

5. The test method of the semiconductor laser according to claim 4, characterized in that, In the first laser bar, the target laser unit and the laser unit under test are alternately arranged along the first direction.

6. The test method of the semiconductor laser according to claim 4, characterized in that The first laser bar includes a target laser unit area and a laser unit under test area arranged along the first direction, the target laser unit area includes a plurality of the target laser units arranged in sequence along the first direction, and the laser unit under test area includes a plurality of the laser units under test arranged in sequence along the first direction.

7. The test method of the semiconductor laser according to claim 4, characterized in that In the first laser bar, two target laser units and one laser unit under test are alternately arranged along the first direction.

8. The test method of the semiconductor laser according to any one of claims 5-7, characterized in that, The preparation of the first laser bar includes: Preparing a laser array, where the laser array includes a plurality of laser bars arranged in sequence and integrally formed along the second direction, and at least one of the plurality of laser bars is the first laser bar; Cleaving the laser array to form at least one first laser bar.

9. According to the test method of the semiconductor laser as claimed in claim 8, characterized in that After preparing a laser unit under test with the same current density as the target laser unit and before performing an aging treatment on the laser unit under test, it further includes: performing a packaging treatment on the laser unit under test; performing a packaging test on the laser unit under test after the packaging treatment; After obtaining the target laser unit with qualified reliability on the premise that the reliability test result of the laser unit to be tested is qualified, it further includes: performing packaging treatment on the target laser unit; performing packaging test on the target laser unit after the packaging treatment.

10. The test method of the semiconductor laser according to claim 9, wherein The aging treatment of the laser unit to be tested includes: performing preliminary screening treatment on the laser unit to be tested on the premise that the packaging test result of the laser unit to be tested is qualified; performing aging treatment on the laser unit to be tested after the preliminary screening treatment; After performing the packaging test on the target laser unit after the packaging treatment, it further includes: performing preliminary screening treatment on the target laser unit on the premise that the packaging test result of the target laser unit is qualified; performing performance test on the target laser unit after the preliminary screening treatment.

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