Dummy bar and end face film forming method of laser diode bar

Abstract

The dummy bar of the present invention is used when forming an insulating film on the front end face (32) and the rear end face (34) of a laser diode bar (30), and comprises: a main body (12) having a plate shape and having a pair of side faces (14) perpendicular to the longitudinal direction and opposite to each other, and an upper surface (16) and a lower surface (18) perpendicular to the pair of side faces and parallel to the thickness direction of the plate shape and opposite to each other, wherein the length of the main body in the longitudinal direction is the same as the length of the laser diode bar (30); and a handle (20) provided at a position separated from the lower surface (18) in the pair of side faces (14).

Description

Technical Field

[0001] The present disclosure relates to a dummy bar used when forming an insulating film on an end face of a laser diode bar, and a method for forming a film on an end face of a laser diode bar using the dummy bar. Background Art

[0002] Laser diodes resonate light through resonators between their end faces, allowing some of the light to escape from the end faces. To achieve this resonance, an insulating film with controlled reflectivity must be deposited on the laser diode's end faces. This insulating film also protects the laser diode's end faces.

[0003] In order to form an insulating film on the end face of the laser diode, first, a semiconductor substrate wafer formed by forming a plurality of laser diode elements into a grid pattern is cleaved and separated to form a laser diode bar. Then, as disclosed in Patent Document 1, dummy bars and laser diode bars are alternately arranged and fixed on a plate having an opening. At this time, the lower surface of the dummy bar is aligned with the end face of one side of the laser diode bar, and the dummy bar is arranged in such a way that the end face faces the opening. The length of the dummy bar in the longitudinal direction is longer than the length of the laser diode bar in the longitudinal direction. Therefore, in the above-mentioned arrangement process, the dummy bar has good operability. Then, an insulating film is sequentially formed on the two end faces of the laser diode bar.

[0004] The above-mentioned plate is contaminated by the insulating film material during film formation on the end surface, and therefore needs to be cleaned. Cleaning allows the plate to be reused multiple times.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-123374

[0006] However, cleaning the plate causes wear around the openings. If a worn plate is used to form a film on the laser diode end face, and dummy bars and laser diode bars are arranged on the plate, the laser diode bars, which are shorter in length than the dummy bars, will sink in the worn areas of the plate. This results in an offset between the dummy bars and the laser diode bars. This offset causes a change in the amount of insulating film that spreads from the laser diode bar end face during film formation. This change in the amount of insulating film reduces the reliability of the insulating film formed on the laser diode bar end face. Summary of the Invention

[0007] The present disclosure is made to address the above-mentioned problems, and its purpose is to provide a dummy bar with good operability, capable of highly accurately controlling the amount of insulating film that spreads onto the end face of a laser diode bar during film deposition, even when the plate is worn. Furthermore, a method for depositing a film on the end face of a laser diode bar is provided, which provides a dummy bar with good operability, capable of highly accurately controlling the amount of insulating film that spreads onto the end face during film deposition, even when the plate is worn.

[0008] The dummy bar disclosed herein is used when forming an insulating film on the front end and rear end faces of a laser diode bar, and comprises: a main body portion having a plate shape and having: a pair of side surfaces perpendicular to the longitudinal direction and opposing each other; and an upper surface and a lower surface perpendicular to the pair of side surfaces and parallel to the thickness direction of the plate shape and opposing each other, wherein the length of the main body portion in the longitudinal direction is the same as the length of the laser diode bar in the longitudinal direction; and a handle portion provided at a position separated from the lower surface on the pair of side surfaces.

[0009] In addition, the end face film forming method of the laser diode bar disclosed in the present invention includes the following steps: a step of alternately arranging the above-mentioned dummy bars and laser diode bars on a plate having an opening, aligning the lower surface of the dummy bars with the end face of one of the front end face and the rear end face of the laser diode bar, and making the end face of one face face the opening; a step of forming an insulating film on the end face of the other side opposite to the one end face; and a step of forming an insulating film on the end face of one side through the opening.

[0010] According to the dummy bar and the method for forming a film on the end face of a laser diode bar disclosed herein, the dummy bar has good operability and the amount of the insulating film that spreads onto the end face of the laser diode bar during film formation can be controlled with high precision even when the plate is worn. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a diagram showing a dummy bar in the first embodiment.

[0012] Figure 2 This is a diagram showing a state where dummy bars and laser diode bars according to the first embodiment are arranged.

[0013] Figure 3 These are diagrams for explaining the method of forming a film on the end face of the laser diode bar according to the first embodiment.

[0014] Figure 4 These are diagrams for explaining the method of forming a film on the end face of the laser diode bar according to the first embodiment.

[0015] Figure 5 These are diagrams for explaining the method of forming a film on the end face of the laser diode bar according to the first embodiment.

[0016] Figure 6 These are diagrams for explaining the method of forming a film on the end face of the laser diode bar according to the first embodiment.

[0017] Figure 7 This figure shows a state where conventional dummy bars and laser diode bars are arranged on a worn plate.

[0018] Figure 8 This is a diagram showing a state where the dummy bars and the laser diode bar of the first embodiment are arranged on a worn plate.

[0019] Figure 9 This is a diagram showing a dummy bar in the second embodiment.

[0020] Figure 10 This is a diagram showing a state where dummy bars and laser diode bars according to the second embodiment are arranged.

[0021] Figure 11 This is a diagram for explaining a method for forming a film on an end face of a laser diode bar according to the second embodiment.

[0022] Figure 12 This is a diagram for explaining a method for forming a film on an end face of a laser diode bar according to the second embodiment.

[0023] Figure 13 This is a diagram for explaining a method for forming a film on an end face of a laser diode bar according to the second embodiment. DETAILED DESCRIPTION

[0024] Implementation method 1.

[0025] The structure of the dummy bar in the first embodiment will be described. Figure 1 The dummy bar 10 of this embodiment is shown. The dummy bar 10 is made of, for example, stainless steel (SUS). Figure 2 This figure shows a state where dummy bars 10 and laser diode bars 30 are alternately arranged. The laser diode bar is formed by cleaving a semiconductor substrate wafer on which a plurality of laser diode elements are formed in a grid pattern.

[0026] The dummy bar 10 includes a main body 12 and a handle 20. The main body 12 has a plate shape and includes a pair of side surfaces 14 perpendicular to the longitudinal direction and opposing each other, and an upper surface 16 and a lower surface 18 perpendicular to the side surfaces 14 and parallel to the thickness direction of the plate and opposing each other. The longitudinal length of the main body 12 is the same as the longitudinal length of the laser diode bar 30. Furthermore, the length from the upper surface 16 to the lower surface 18 of the main body 12 is shorter than the length from the front end 32 to the rear end 34 of the laser diode bar 30. The handle 20 is provided at a position separated from the lower surface 18 on the pair of side surfaces 14.

[0027] Next, a method for forming films on the end faces of a laser diode bar using dummy bar 10 will be described. Although not shown, resonators are arranged along the length of the laser diode bar 30 between the front facet 32 and the rear facet 34. Here, the front facet refers to the surface from which laser light is emitted, and the rear facet refers to the end face opposite the front facet. In order for the resonators to resonate light, an insulating film with controlled reflectivity must be formed on the front facet 32 and the rear facet 34. This film formation method will be described below.

[0028] First, if Figure 3 As shown, dummy bars 10 and laser diode bars 30 are arranged on a plate 40 having openings 42. At this time, dummy bars 10 and laser diode bars 30 are arranged alternately. Dummy bars 10 are placed between laser diode bars 30 to prevent the laser diode bars 30 from being closely attached to each other. Figure 2 4 shows a case where dummy bars 10 and laser diode bars 30 are alternately arranged. Furthermore, the lower surface 18 of the dummy bar 10 is aligned with the rear end face 34 of the laser diode bar 30, and the dummy bar 10 is arranged so that the rear end face 34 faces the opening 42. In this manner, when arranging the dummy bar 10 and the laser diode bar 30, an operator or a machine can grasp the handle 20 with a clamp such as tweezers, thereby improving the operability of the dummy bar 10.

[0029] Next, the dummy bar 10 and the laser diode bar 30 are fixed to the plate 40. The fixing method is not particularly limited, but for example Figure 4 As shown, the dummy bar 10 and the laser diode bar 30 are directed toward the stopper 44 fixed to the plate 40 and are pressed and fixed in the direction of the arrow using the fixing jig 46 .

[0030] Next, if Figure 5 As shown, an insulating film 22 is formed on the front face 32 of the laser diode bar 30. Vacuum evaporation, sputtering, or chemical vapor deposition (CVD) is used to form the film on the front face 32. In this process, the insulating film 22 not only extends to the front face 32 but also extends to the side surfaces. Generally, to ensure good control and desired insulating film formation, the end face (front face 32 or rear face 34) of the laser diode bar 30 must be aligned with or protrude from the end face (upper surface 16 or lower surface 18) of the dummy bar 10. Therefore, the length between the front and rear facets of the laser diode bar 30 must be the same as the length between the upper and lower surfaces of the dummy bar 10, or longer than the length between the upper and lower surfaces of the dummy bar 10 to account for dimensional variations in the laser diode bar 30 and dummy bar 10. In this embodiment, the length between the front and rear facets of the laser diode bar 30 is longer than the length between the upper and lower surfaces of the dummy bar 10. This allows the insulating film 22 on the front face 32 to also be formed on the side surfaces, improving the reliability of the insulating film 22 on the front face 32. Forming the insulating film 22 also on the side surfaces is effective when, for example, the front facet 32, which emits laser light, is required to have higher reliability than the rear facet 34. However, if the amount of insulating film 22 protrudes, this can reduce the heat dissipation of the laser diode chips when they are separated and mounted on a submount. Therefore, the amount of insulating film protrusion must be precisely controlled.

[0031] The amount of the insulating film 22 that spreads from the front end face 32 to the side is controlled with high precision. The reason is as follows: Since the lower surface 18 of the dummy bar 10 is aligned with the rear end face 34 of the laser diode bar 30, the length L1 of the insulating film 22 that spreads from the front end face 32 is constant. The portion of L1 is Figure 5 Shown in.

[0032] Next, the plate 40 to which the dummy bar 10 and the laser diode bar 30 are fixed is turned upside down, and an insulating film is formed on the rear end face 34 of the laser diode bar 30 through the opening 42. However, depending on the configuration of the film forming device, it is sometimes not necessary to turn it upside down. The method used for forming the film on the rear end face 34 is the same as that for forming the film on the front end face 32. The rear end face 34 is basically a surface from which no laser is emitted. Even if it is emitted, it is only low-output light for monitoring. Therefore, there is also a case where the reliability of the insulating film like that of the front end face 32 is not required. In this case, there is no need for the spreading of the insulating film. If the amount of spreading of the insulating film increases, the heat dissipation of the laser diode chip will be reduced when it is separated into laser diode chips and mounted on a sub-mount.

[0033] There is no insulating film formed on the side surface that spreads from the rear end face 34 . The reason for this is to align the lower surface 18 of the dummy bar 10 with the rear end face 34 of the laser diode bar 30 .

[0034] The above process completes the film formation on the end face of the laser diode bar 30, and Figure 6 As shown, a laser diode bar is completed in which the insulating film 22 is formed on the front face 32 and the insulating film 24 is formed on the rear face 34 .

[0035] Next, the wear of the plate 40 will be described.

[0036] The plate 40 is contaminated by the insulating film material during film formation on the end faces of the laser diode bar 30. Therefore, the plate 40 is cleaned to remove the adhered insulating film material. This cleaning allows the plate 40 to be reused multiple times. Cleaning is performed using a mechanical method or a method using chemicals.

[0037] However, if the plate 40 is cleaned, the area around the opening 42 will be worn. If the conventional dummy bars 50 and the laser diode bars 30 are arranged on the worn plate 40, as shown in FIG. Figure 7 As shown, at the worn portion, the laser diode bar 30 has sunk relative to the conventional dummy bar 50. Here, the conventional dummy bar 50 is a rectangular parallelepiped dummy bar made longer than the laser diode bar 30 in the longitudinal direction.

[0038] Because the laser diode bar 30 sinks, the conventional dummy bar 50 is offset from the laser diode bar 30. This offset changes the amount of insulating film that spreads from the end face during film formation, reducing the reliability of the insulating film. Furthermore, the increased amount of insulating film spread reduces the heat dissipation of the laser diode chip.

[0039] On the other hand, the length of the main body 12 of the dummy bar 10 of this embodiment is the same as the length of the laser diode bar 30, and the handle 20 is provided at a position away from the lower surface 18 within the pair of side surfaces 14. Figure 8 As shown, when the plate 40 is worn, the dummy bar 10 and the laser diode bar 30 sink in the same manner, so there is no displacement between the dummy bar 10 and the laser diode bar 30. As a result, even when the plate 40 is worn, the amount of the insulating film that spreads onto the end face of the laser diode bar 30 during film formation can be controlled with high precision.

[0040] As described above, according to this embodiment, the dummy bar 10 has the handle 20, which improves the operability of the dummy bar 10. Furthermore, the length of the main body 12 of the dummy bar 10 is the same as the length of the laser diode bar 30, and the handle 20 is positioned within the pair of side surfaces 14 at a position away from the lower surface 18. Therefore, even if the plate 40 is worn, the amount of insulating film that spreads onto the end face of the laser diode bar 30 during film deposition can be controlled with high precision.

[0041] In addition, since the length of the dummy bar 10 from the upper surface 16 to the lower surface 18 of the main body 12 is shorter than the length from the front end face 32 to the rear end face 34 of the laser diode bar 30, when the insulating film is formed on the front end face 32, the insulating film 22 is also formed on the side surface, thereby improving the reliability of the insulating film 22 formed on the front end face 32.

[0042] Furthermore, when arranging the dummy bar 10 and the laser diode bar 30 on the plate 40 , the lower surface 18 of the dummy bar 10 is aligned with the rear end face 34 of the laser diode bar 30 . This prevents the insulating film formed on the rear end face 34 from spreading to the side surfaces.

[0043] Furthermore, the reliability required of the end faces of the laser diode bar 30 may not only be higher for the front face 32 than for the rear face 34, but also higher for the rear face 34, or the same for the front face 32 and rear face 34. Therefore, the length from the upper surface 16 to the lower surface 18 of the main body 12 may be the same as the length from the front face 32 to the rear face 34 of the laser diode bar 30. Furthermore, when arranging the dummy bar 10 and the laser diode bar 30, the front face 32, rather than the rear face 34, may be aligned with the lower surface 18 of the dummy bar 10. Specifically, the lower surface 18 is aligned with one of the end faces 32 and 34, and an insulating film is formed on the end face opposite the one end face, and the insulating film is formed on one end face through the opening 42.

[0044] Furthermore, the order of film formation on the front end face 32 and the rear end face 34 does not necessarily need to start from the rear end face 34 , and film formation may also start from the front end face 32 .

[0045] Implementation method 2.

[0046] The structure of the dummy bar in the second embodiment will be described. Figure 9 A dummy bar 60 of this embodiment is shown in FIG. Figure 10 This is a diagram showing a state where dummy bars 60 and laser diode bars 30 are alternately arranged.

[0047] The dummy bar 60 includes a main body 62 and a handle 70. The length from the upper surface 66 to the lower surface 68 of the main body 62 is the same as the length from the front end 32 to the rear end 34 of the laser diode bar 30. The main body 62 has a recess 76 on the lower surface 68. The recess 76 is U-shaped when viewed from the thickness of the plate. The handle 70 is provided within the pair of side surfaces 64 at a position separated from the lower surface 68. Aside from the length from the upper surface 66 to the lower surface 68 and the recess 76, the dummy bar 60 is identical to the dummy bar 10 of the first embodiment.

[0048] Next, a method of forming a film on the end face of a laser diode bar using the dummy bar 60 will be described.

[0049] First, if Figure 11 As shown, the dummy bars 60 and the laser diode bars 30 are arranged on the plate 40 having the openings 42. At this time, the dummy bars 60 and the laser diode bars 30 are arranged alternately. Figure 10 , dummy bars 60 and laser diode bars 30 are alternately arranged. The bottom surfaces 68 of the dummy bars 60 are aligned with the front end surfaces 32 of the laser diode bars 30 , and the dummy bars 60 are arranged so that the front end surfaces 32 face the openings 42 .

[0050] Next, similarly to the first embodiment, the dummy bar 60 and the laser diode bar 30 are fixed to the plate 40 .

[0051] Next, an insulating film is formed on the rear facet 34 of the laser diode bar 30. At this point, the insulating film does not spread from the rear facet 34 to the side surfaces. The reason for this is that the lower surface 68 of the dummy bar 60 is aligned with the front facet 32 of the laser diode bar 30, so that the length from the upper surface 66 to the lower surface 68 is the same as the length from the front facet 32 to the rear facet 34 of the laser diode bar 30.

[0052] Next, the plate 40 to which the dummy bar 60 and the laser diode bar 30 are fixed is turned upside down, and the insulating film 72 is formed on the front end surface 32 of the laser diode bar 30 through the opening 42. However, depending on the configuration of the film forming apparatus, upside-down inversion may not be necessary. Figure 12 After the insulating film 72 is formed on the front end surface 32 Figure 11 The cross-sectional view at A-A of Figure 11 Upside down. At the front end face 32 of the laser diode bar 30, Figure 12 Insulating film 72 is thus formed. At this time, since recessed portion 76 exists in dummy stripe 60, insulating film 72 is formed not only to extend to front end surface 32 but also to extend to the side surface.

[0053] The amount of the insulating film 72 extending from the front end face 32 to the side is controlled with high precision. The reason is as follows: Since the lower surface 68 of the dummy bar 60 is aligned with the front end face 32 of the laser diode bar 30, the length L2 of the insulating film extending from the front end face 32 is constant. The portion of L2 is Figure 12 Shown in.

[0054] The above process completes the film formation on the end face of the laser diode bar 30, and the Figure 13 As shown, the laser diode bar has an insulating film 72 formed on the front face 32 and an insulating film 74 formed on the rear face 34 .

[0055] As described above, according to this embodiment, the dummy bar 60 has the handle 70, which improves the operability of the dummy bar 60. Furthermore, the length of the main body 62 of the dummy bar 60 is the same as the length of the laser diode bar 30, and the handle 70 is provided at a position separated from the lower surface 68 within the pair of side surfaces 64. Therefore, even if the plate 40 is worn, the amount of insulating film that spreads onto the end face of the laser diode bar 30 during film formation can be controlled with high precision.

[0056] In addition, the dummy strip 60 also has a concave portion 76, so when the insulating film is formed on the front end surface 32, as shown in FIG. Figure 11 Since the insulating film 72 is also formed on the side surface in this manner, the reliability of the insulating film 72 formed on the front end surface 32 is improved.

[0057] In addition, the lower surface 68 of the dummy bar 60 is aligned with the front end face 32 of the laser diode bar 30, and the length from the upper surface 66 to the lower surface 68 is the same as the length from the front end face 32 to the rear end face 34 of the laser diode bar 30. Therefore, the insulating film formed on the rear end face 34 does not spread to the side.

[0058] Furthermore, since the lower surface 68 of the dummy bar 60 is aligned with the front end face 32 of the laser diode bar 30 , even if the resonator length of the laser diode bar 30 varies, the amount of the insulating film 72 extending to the side surface on the front end face 32 side is not affected by the variation, and the amount of the insulating film 72 extending to the side surface on the front end face 32 side is constant.

[0059] Furthermore, as described in Embodiment 1, the length from the upper surface 66 to the lower surface 68 may be shorter than the length from the front end face 32 to the rear end face 34 of the laser diode bar 30. In this case, although the insulating film 74 formed on the rear end face 34 also spreads to the side surface, the amount of spread is controlled. Furthermore, when arranging the dummy bar 60 and the laser diode bar 30, the rear end face 34, rather than the front end face 32, may be aligned with the lower surface 68 of the dummy bar 60. Specifically, the lower surface 68 is aligned with one end face of the front end face 32 or the rear end face 34, the insulating film is formed on the end face opposite the one end face, and the insulating film is formed on one end face through the opening 42.

[0060] Furthermore, the order of film formation on the front end face 32 and the rear end face 34 does not necessarily have to start from the front end face 32 , but may also start from the rear end face 34 .

[0061] Description of Reference Numerals

[0062] 10, 60...dummy bar; 12, 62...main body; 14, 64...a pair of side surfaces; 16, 66...upper surface; 18, 68...lower surface; 20, 70...handle; 22, 72...insulating film; 24, 74...insulating film; 76...recess; 30...laser diode bar; 32...front end surface; 34...rear end surface; 40...plate; 42...opening; 44...stopper; 46...fixing fixture; 50...conventional dummy bar.

Claims

1. A dummy bar used when forming an insulating film on the front end face and the rear end face of a laser diode bar, characterized in that: have: a main body having a plate shape and having: a pair of side surfaces perpendicular to the longitudinal direction and opposing each other; and an upper surface and a lower surface perpendicular to the pair of side surfaces and parallel to the thickness direction of the plate shape and opposing each other, wherein the length of the main body in the longitudinal direction is the same as the length of the laser diode bar in the longitudinal direction; and a handle portion provided at a position away from the lower surface among the pair of side surfaces, In a thickness direction of the plate shape, a plurality of the dummy bars and a plurality of the laser diode bars are alternately arranged.

2. The dummy strip according to claim 1, wherein: A length from the upper surface to the lower surface is shorter than a length from the front end surface to the rear end surface.

3. The dummy strip according to claim 1, wherein: The main body portion is provided on the lower surface with a recessed portion having a U-shape when viewed in the thickness direction of the plate shape.

4. The dummy strip according to claim 3, wherein: The length from the upper surface to the lower surface is the same as the length from the front end surface to the rear end surface.

5. A method for forming a film on the end face of a laser diode bar, characterized in that: With the following processes: The process of alternately arranging the dummy bars and the laser diode bar according to any one of claims 1 to 4 on a plate having an opening, aligning the lower surface of the dummy bars with one of the front end face and the rear end face of the laser diode bar, and making the one end face face the opening: forming an insulating film on the other end surface facing the one end surface; and a step of forming an insulating film on the one end surface through the opening.

6. The method for forming a film on an end face of a laser diode bar according to claim 5, wherein: The dummy bar is the dummy bar according to claim 2, The one end surface is the rear end surface.

7. The method for forming a film on an end face of a laser diode bar according to claim 5, wherein: The dummy bar is the dummy bar according to claim 3 or 4, The one end surface is the front end surface.

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