JP2017069384A - Manufacturing method for sub-mount - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method capable of keeping high cleanliness by forming a plurality of sub-mounts from a substrate, and removing contamination occurring in the manufacturing process, without damaging a metal film formed on the surface of the sub-mounts.SOLUTION: A manufacturing method for sub-mount includes a first outer shape formation step S110 of forming at least one face of a sub-mount, a substrate cleaning step S120 of cleaning the substrate, a metal film formation step S130 of forming a metal film on the front face including the face of a sub-mount cleaned by the substrate cleaning step S120, and a second outer shape formation step S140 of forming at least one face of a sub-mount, excluding the face formed by the first outer shape formation step S110. With such an arrangement, high cleanliness is kept by removing contamination occurring in the manufacturing process effectively, without damaging the metal film.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method of manufacturing a submount on which a semiconductor laser element or the like is mounted as a module for an optical device (a pickup for an HDD / DVD recorder, optical communication).

  In recent years, it has been known that a module for an optical device has a semiconductor laser element or the like mounted on a head portion via a chip component (hereinafter referred to as a submount). The submount mounts the semiconductor laser element on the upper surface with high accuracy, and the side surface connected to the upper surface of the submount is mounted on the head portion as a mounting surface to the head portion. At this time, the upper surface of the submount on which the semiconductor laser element is mounted is required to have a high squareness with respect to the side surface that is the mounting surface to the head portion.

  Such submounts are very small (eg, a size of 0.5 mm or less on each side), and many can be manufactured from, for example, a 6 inch substrate. Then, by mounting a semiconductor laser element or the like, it is used as a semiconductor laser device or an optical device having the semiconductor laser device mounted thereon, and many proposals relating to the technology have been made (for example, see Patent Document 1).

  In the prior art described in Patent Document 1, the manufacturing process of the semiconductor laser element is performed by dividing into a predetermined semiconductor laminated film forming step, ridge portion forming step, electrode forming step, and cutting step on a wafer-like semiconductor substrate. After that, a semiconductor laser element is formed.

  On the other hand, the submount manufacturing process includes a process of forming a plurality of submounts on a wafer-like substrate, a brazing material forming process of performing predetermined electrode patterning on the surface side where the semiconductor laser element is installed, and a heat dissipation material on the opposing surface of the substrate The submount is formed through a lower surface heat radiation layer forming step of forming a film and a submount singulation step of cutting into a lattice shape.

  Next, the semiconductor laser device is obtained by bonding the electrode of the semiconductor laser element onto the brazing material of the submount that has been separated into pieces. Since the semiconductor laser device has a heat dissipation material mainly composed of carbon laminated on the back surface of the submount, a light-weight and high heat dissipation semiconductor laser device is obtained.

  The prior art disclosed in Patent Document 1 manufactures a semiconductor laser device by such a manufacturing method so that laser light can be accurately irradiated to an optical waveguide provided in a magnetic recording head.

JP 2014-229337 A (FIGS. 1 to 7)

  By the way, according to the second embodiment described in Patent Document 1, a step of forming a brazing material (metal film) serving as an electrode on the upper surface of the submount substrate, a groove portion (hereinafter referred to as a slit) is formed by dry etching. An example of a submount manufacturing method in which a submount is divided into individual pieces after forming a submount and dividing the submount, and forming a heat dissipation layer is described.

  When slits are formed on the substrate by dry etching in this way, the slit side surface has a high squareness with respect to the upper surface of the substrate, but various contaminations (hereinafter referred to as contamination) are likely to remain in the substrate, and the submount is optically When mounting on a device or the like, there is a concern that contamination enters the mounting surface of the submount and the mounting surface of the optical device or the like, thereby adversely affecting the perpendicularity of the submount with respect to the optical device or the like.

  However, according to the second embodiment of Patent Document 1, it is a process of forming a slit by dry etching on the substrate after the formation of the brazing material (metal film). Cleaning with can not be performed. On the other hand, there is a problem that a substrate cleaning method that does not use an acid tends to cause contamination and a clean submount cannot be obtained.

(Object of invention)
An object of the present invention is to solve the above-described problems and to provide a method for manufacturing a submount that can maintain high cleanliness without damaging a metal film. It is another object of the present invention to provide a manufacturing method that has a surface having a high squareness and has improved manufacturing time reduction and wafer level handling of a substrate.

The manufacturing method of the submount in the present invention is as follows.
In a submount manufacturing method for forming a submount from a substrate, a first contour forming step of processing the substrate to form at least one surface of the submount, and the substrate after the first contour forming step Except for the substrate cleaning step for cleaning the substrate, the metal film forming step for forming a metal film on the surface of the submount cleaned by the substrate cleaning step, and the surface formed in the first outer shape forming step. And a second outer shape forming step for forming at least one surface of the submount.

  As a result, at least one surface of the submount is formed by the first outer shape forming process, and then the substrate is cleaned by the substrate cleaning process. Therefore, the contamination generated in the first outer shape forming process is removed from the substrate and cleaned. Submount can be obtained. Since the metal film forming step is performed after the substrate cleaning step, a submount manufacturing method capable of maintaining high cleanliness without damaging the metal film due to cleaning becomes possible.

  Further, since the substrate surface is kept clean in the metal film forming step, a metal film with high adhesion can be formed.

  Further, the substrate cleaning step may include a cleaning step using an acid.

  As a result, the contamination generated in the first outer shape forming process is removed from the substrate by strong cleaning, and a method for manufacturing a submount with higher cleanliness becomes possible.

  The first outer shape forming step may be a step of forming at least one side surface of the submount by dry etching the substrate.

  Thus, the surface of the submount formed from the substrate by the first outer shape forming step can obtain a high squareness.

  In addition, a surface oxide film forming step for forming an oxide film on the surface of the substrate may be provided before the substrate cleaning step.

  Thereby, since a stronger cleaning can be performed by forming a stable oxide film on the surface of the substrate, contamination can be more effectively removed.

  Further, the substrate cleaning process may include a cleaning process using a hydrofluoric acid solution.

  As a result, it is possible to dissolve and remove even the surface oxide film formed on the substrate surface and the contamination taken into the surface oxide film by washing with the hydrofluoric acid solution. Can be obtained. At the same time, the smoothness of the surface of the submount can be improved.

  Further, the metal film forming step may be a step of laminating and forming a base metal film layer and an adhesive metal film layer as a metal film.

  Thereby, for example, an adhesion layer, a barrier layer, a conductive layer, etc. are laminated on the surface of the submount as a base metal film layer, and an adhesive metal film layer is formed thereon to ensure reliable mechanical connection with other members, Electrical bonding can be performed.

  The second outer shape forming step may be performed by machining.

  Thereby, the side surface which does not require the perpendicularity of the submount can be formed by machining, so that the processing time can be shortened and the submount can be easily separated from the substrate.

  Further, the side surfaces of the submount formed by the first outer shape forming step are two opposite surfaces, and the surfaces formed by the second outer shape forming step are other two opposite surfaces orthogonal to the two opposite surfaces. Good.

  Thereby, by suitably combining the two outer shape forming steps, one of the two opposing surfaces of the submount can accurately form a surface having a high squareness by etching or the like, and the other two opposing surfaces can be machined or the like. As a result, the processing time can be shortened.

  In the first outer shape forming step, a wide frame-shaped slit may be formed by forming a thin frame-shaped slit and removing an island-shaped portion inside the frame-shaped slit.

  Thereby, even if the side surface formed by the first outer shape forming step is wide, a side surface with higher verticality can be obtained. In addition, the metal film can be simultaneously formed on the side surface and the surface of the submount.

  The substrate may be a silicon substrate.

  According to the submount manufacturing method of the present invention, it is possible to provide a submount that maintains high cleanliness without damaging the metal film.

It is the perspective view and sectional drawing for demonstrating the structure of the submount manufactured by the manufacturing method of the 1st Embodiment of this invention. It is a manufacturing process figure explaining the manufacturing method of the 1st Embodiment of this invention. FIG. 3 is a plan view and a perspective view illustrating a first outer shape forming step in the process diagram of FIG. 2. It is the top view and perspective view explaining the metal film formation process of the process drawing of FIG. It is the top view and perspective view explaining the 2nd external shape formation process of the process drawing of FIG. It is a manufacturing process figure explaining the manufacturing method of the 2nd Embodiment of this invention. FIG. 7 is a schematic cross-sectional view illustrating a first outer shape forming process, a surface oxide film forming process, and an acid cleaning process in the process diagram of FIG. 6. It is the perspective view and partial enlarged view explaining the manufacturing method of the 3rd Embodiment of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. However, the embodiment described below exemplifies a method of manufacturing a submount for embodying the idea of the present invention, and the present invention is not limited to the method and configuration described below. In particular, the manufacturing method and the shape, material, relative arrangement, etc. of the members described in the embodiments are merely illustrative examples and not intended to limit the scope of the present invention unless otherwise specified. . In addition, the manufacturing method and the size, shape, positional relationship, and the like of the members shown in each drawing may be exaggerated for easy understanding.

  The submount manufacturing method of the present invention provides a submount manufacturing method capable of maintaining high cleanliness without damaging a metal film formed on the submount.

  In order to realize such a submount manufacturing method, a first outer shape forming process for forming at least one surface of the submount, a substrate cleaning process for cleaning the substrate, and a sub cleaned by the substrate cleaning process A metal film forming step for forming a metal film on the surface of the mount; and a second outer shape forming step for forming at least one surface of the submount excluding the surface formed in the first outer shape forming step. .

  By using such a manufacturing method, a submount having a high squareness can be formed and contamination can be effectively removed. In addition, a manufacturing method capable of maintaining high cleanliness without damaging the metal film formed on the submount has become possible.

First, the first embodiment will be described with reference to FIGS. 1 to 5, the second embodiment will be described with reference to FIGS. 6 to 7, and then the third embodiment will be described with reference to FIG. 8. Will be explained.
In the description, the same elements are denoted by the same reference numerals, and duplicate descriptions are omitted. Further, parts not related to the invention are omitted.

[Description of First Embodiment: FIGS. 1 to 5]
FIG. 1 shows a configuration of a submount manufactured by the manufacturing method of the present invention, and FIG. 2 shows a flowchart of a manufacturing process of the first embodiment. 3, FIG. 4, and FIG. 5 show the steps of S110, S130, and S140 shown in FIG. 2 with a plan view and a perspective view, respectively.

[Submount configuration: Fig. 1]
FIG. 1A is a perspective view of the submount 20, and FIG. 1B is a cross-sectional view taken along the line AA 'in FIG. As shown in FIGS. 1A and 1B, the submount 20 is a rectangular parallelepiped formed from a substrate. The side surface 20S is one of the side surfaces of the submount 20 formed from a substrate, and is a mounting surface when the submount 20 is mounted on an attachment such as a head portion. The two side surfaces 20K and 20K ′ adjacent to the side surface 20S and the side surface 20S ′ facing the side surface 20S are other side surfaces formed when the submount 20 is separated from the substrate. Further, the upper surface 20J corresponds to the upper surface of the substrate, and the lower surface 20J ′ corresponds to the lower surface of the substrate.

  When the submount 20 is mounted on an object to be mounted such as an optical device (not shown), the side surface 20S is mounted. In this case, it is necessary to form a metal film on the side surface 20S. Further, when a semiconductor laser element (not shown), for example, is mounted on the upper surface 20J, it is necessary to form a metal film in the same manner. Therefore, as shown in FIG. 1, a metal film 21 is formed on the side surface 20S and the upper surface 20J by a method such as sputtering.

  Here, the metal film 21 shown in FIG. 1 is separated by the side surface 20S and the upper surface 20J, but may be connected according to the purpose. Further, as a film layer configuration of the metal film, for example, Ti / Pt / Au may be formed in this order from the lower layer side. Ti serves as an adhesion layer with the substrate, Pt serves as an anti-diffusion layer for Au to the substrate, and Au serves as a bonding holding layer with, for example, Au / Sn solder.

  When the metal film 21 is formed from the upper surface side of the substrate, it can be simultaneously formed on the upper surface 20J and the side surface 20S by securing a necessary amount of slits for forming the side surface 20S as will be described later.

  Next, a metal film 22 as shown in FIG. 1 is formed on the upper surface of the metal film 21 on the upper surface 20J of the submount 20 in order to mount, for example, a semiconductor laser element. For example, an AuSn solder film may be laminated.

  In the submount 20, for example, a semiconductor laser element or the like is mounted on the upper surface 20J using a metal film 22 made of an AuSn film, and the side surface 20S of the submount 20 is mounted on a predetermined position of the optical device, for example. it can. As a result, light emitted from the semiconductor laser element or the like can be guided to a predetermined position of the optical device with a predetermined accuracy.

[Manufacturing process flowchart: FIG. 2]
Next, a manufacturing process flowchart is shown in FIG. 2, and first, the manufacturing method of the first embodiment will be described. Here, an example in which silicon (Si), which is a semiconductor material, is used as the substrate material will be described. In the following steps, unless otherwise specified, it is natural to perform predetermined inspections, predetermined cleanings, and the like necessary for the respective steps, and detailed descriptions thereof will be omitted.

[Board acceptance process]
First, in the substrate receiving step S100, predetermined inspection, predetermined cleaning, and the like of the substrate are performed.

[First outline forming step]
Next, in order to form a plurality of submounts on the substrate, a first outer shape forming step S110 is performed to form slits for forming side surfaces that become mounting surfaces of the submounts.

[Substrate cleaning process]
Next, a substrate cleaning step S120 is performed on the substrate on which the slit has been formed in the first outer shape forming step, and contamination is removed.

[Metal film forming process]
Next, a metal film forming step S130 is performed on each submount portion of the substrate cleaned by the substrate cleaning process to form a predetermined metal film.

[Second outline forming step]
Next, in each submount portion formed on the substrate, the second outer shape forming step S140 is performed to form side surfaces other than the side surfaces formed in the first outer shape forming step, and each submount is separated from the substrate.

[More Specific Description of Each Step: FIGS. 3 to 5]
Next, each step will be described more specifically in the order of the manufacturing process flowchart of FIG. 2 with reference to FIGS. Here, detailed description of the substrate receiving step S100 is omitted.

[First Outline Forming Step S110: FIG. 3]
FIG. 3A shows a state in which a plurality of submounts 20 (shown by broken lines) are formed on the substrate 10, and shows a part of the substrate 10 in an enlarged manner. FIG. 3B shows the same portion of the substrate 10 in a three-dimensional view in a perspective view.
First, in FIGS. 3A and 3B, the first outer shape forming step S110 will be described. A resist pattern is formed on the substrate 10 made of silicon and having a predetermined thickness by, for example, photolithography, and a plurality of slits 12 penetrating from the upper surface to the lower surface of the substrate 10 are formed by a method such as etching. Each slit 12 has a side surface 20S to be a mounting surface of each submount 20, and the side surface 20S of the submount 20 is formed respectively.

  Each submount 20 indicated by a broken line is arranged in a lattice form in the vertical and horizontal directions, and the same slit 12 is formed on the opposite surface side of the side surface 20S of one submount 20 as shown in FIG. Has been. Further, the slit 12 on the opposite surface side forms a side surface 20S of the submount 20 adjacent in the Y direction. In this manner, a plurality of rows of submounts 20 are formed in the Y direction, and a plurality of rows are arranged in the X direction. The cross section BB ′ shown in FIG. 3B will be described in a second embodiment to be described later.

  As described above, the slits 12 are arranged so as to be shared by the adjacent submounts 20, whereby efficient multi-piece production is possible. In addition, the slit 12 is not limited to the example arrange | positioned so that it may share, You may arrange | position the intrinsic | native slit 12 in the position which hits the both end surfaces of each submount 20. FIG. Here, although not particularly limited, a method of forming the slit 20 can be performed by, for example, wet etching, dry etching, blasting, or the like.

[Substrate cleaning step S120]
Next, the substrate cleaning process will be described. For example, when the slit is formed in the substrate 10 described above by the first outer shape forming step S110, in a predetermined process such as resist pattern formation or etching, contamination such as particulate contamination, metal contamination, organic contamination, etc. It is necessary to remove these contaminants. In particular, if metal contaminants remain in the slit, the perpendicularity between the mounted object and the submount when the submount is mounted on a mounted object such as an optical device may be affected. In order to remove metal contaminants from these contaminants, cleaning with an acid is effective.

  In the substrate cleaning process, cleaning corresponding to each contaminant is performed. Here, an example of cleaning using an acid for mainly removing metal contaminant will be described. For removing such metal contaminants, for example, cleaning with an acid such as HPM diluted with ultrapure water by adding hydrochloric acid to hydrogen peroxide water is effective. By performing such cleaning using an acid in a predetermined procedure, metal contaminants can be effectively removed due to the strong acidity.

  Further, by performing cleaning using an acid before the metal film forming step, metal contaminants can be removed without damaging the metal film with acid. Here, although it does not specifically limit, the cleaning method used for a board | substrate cleaning process is mention | raise | lifted. For example, cleaning using an acid, cleaning using an alkali, cleaning using pure water, and the like.

[Metal film forming step S130: FIG. 4]
FIG. 4 shows a state in which a plurality of slits 20 are formed in the substrate 10 and a metal film is formed on each submount 20 in the first outer shape forming step S110 described above.

  It is necessary to form a metal film on the side surface 20S and the upper surface 20J of the submount 20. As shown in FIG. 4A or 4B, as a base metal film forming step, a metal film 21 is formed on the substrate 10 on which a plurality of slits 12 are formed by a method such as sputtering from the upper surface side. As a film layer configuration of the metal film 21, for example, Ti / Pt / Au are formed in this order from the lower layer side.

  Here, if the width of the slit 12 in the Y direction is large to some extent, when the metal film is formed from the upper surface side of the substrate 10, it can be simultaneously formed on the side surface of the slit 12. Then, a resist opening is formed on the formed metal film by photolithography, and the metal film is etched by ion milling or the like to form a predetermined metal film 21 on the upper surface of the substrate 10 and the side surfaces of the slits 12.

  Further, a circuit pattern may be formed on the metal film 21 depending on the application. Further, when a submount 20 to be described later is separated from the substrate 10, if a metal film opening 23 in which a metal film is not formed is provided in a cutting region by machining such as dicing, the submount 20 is formed from the substrate 10. It is possible to prevent burrs of the metal film generated by the contact between the metal film and the tool when singulated.

  Next, as a bonding metal film forming step, a metal film 22 is formed by being laminated on the metal film 21. The metal film 22 has a resist opening on the upper surface of the submount by photolithography, and is formed, for example, in the order of Pt / F—Au / AuSn / F—Au from the lower layer side. As a result, a semiconductor laser element or the like can be mounted and bonded to the submount 20. In addition, although it does not specifically limit, the manufacturing method which forms a metal film is mention | raise | lifted. For example, a vacuum deposition method, a sputtering method, or the like.

[Second Outline Forming Step S140: FIG. 5]
FIG. 5 shows a second outer shape forming step, in which side surfaces other than the side surface 20S of the submount 20 are formed. As shown in FIG. 5A, a cutting groove 17 is formed on the side surface of the submount 20 other than the side surface 20S. For example, the cutting grooves 17 are sequentially formed along each row by cutting using a dicing process (not shown).

  Thereby, as shown in FIG. 5B, the cutting grooves 17 are formed along the respective rows, and the submount 20 on which the metal film is formed from the substrate 10 is singulated. Since the metal film formed on the submount 20 is formed after the substrate cleaning process, each film layer constituting the metal film is not damaged by the cleaning and can be a metal film having high adhesion. Although not particularly limited, a manufacturing method of the second outer shape forming process will be given. For example, dicing processing, laser processing, scribe processing and the like.

[Description of effects]
As described above, the mounting surface having a high squareness can be formed on the side surface of the submount by the first outer shape forming process, and the substrate cleaning process is performed before the metal film forming process. Contaminants can be removed and cleanliness can be maintained without damaging the surface.

  In addition, the metal film can be simultaneously formed on the side surface and the upper surface of the submount or the surface, and the time for forming the metal film can be shortened. Further, the processing time for singulation can be shortened by a suitable combination of etching and machining. As a result, it is possible to provide a method for manufacturing a submount with improved handling of the wafer level process of the substrate.

  In addition, although the material of the board | substrate was demonstrated as a silicon substrate, it is not limited to this, You may use the other material which has the same objective. In addition, the method of forming the opposite two sides of the submount in the first outer shape forming step and forming the other two opposite sides in the second outer shape forming step has been described. However, the present invention is not limited to this and requires a high squareness. At least one side surface may be formed in the first outer shape forming step, and the remaining other side surface may be formed in the second outer shape forming step.

[Explanation of Second Embodiment: FIGS. 6 to 7]
Next, a second embodiment will be described with reference to FIGS. 6 shows a flowchart of the manufacturing process for explaining the manufacturing method of the second embodiment, and FIG. 7 shows a schematic cross-sectional view for explaining the substrate cleaning process.

The feature of the second embodiment is that a surface oxide film forming step is provided before the substrate cleaning step, and a stable oxide film is formed on the surface of the substrate to effectively prevent acid contamination. It is a manufacturing method aiming at effective removal.
Since the configuration of the submount and the first outer shape forming step, the metal film forming step, and the second outer shape forming step in the manufacturing process are basically the same, the description of the first embodiment is given in the description. A part of the description will be made using and a redundant description will be omitted.

[Description of Manufacturing Process Flowchart: FIG. 6]
FIG. 6 shows a manufacturing process flowchart of the second embodiment.
The second embodiment is different from the first embodiment in that a surface oxide film forming step S115 is provided after the first outer shape forming step S110 and before the substrate cleaning step S125. Therefore, the surface oxide film forming step S115 and the substrate cleaning step S125, which are manufacturing steps unique to the second embodiment, will be described more specifically.

[Surface oxide film forming step S115: FIG. 7]
FIG. 7A is an enlarged cross-sectional view schematically showing the slit 12 formed in the substrate 10 by dry etching so that the cross section can be easily explained. Here, FIG. 7A corresponds to the BB ′ cross section shown in FIG. 3B described above. In FIG. 7A, a resist pattern (not shown) is formed on the substrate 10 by photolithography, and the slits 12 are formed by dry etching such as DRIE (Deep Reactive Ion Etching).

  At this time, irregularities (hereinafter referred to as scallops) 15 are formed on the side surface 20S of the slit 12. The scallop 15 is striped unevenness parallel to the upper surface of the substrate 10, and the uneven step is s1. Further, the scallop 15 is continuously formed along the inner periphery of the slit 12. In the slit 12, various contaminants (not shown) generated particularly in the DRIE processing process are attached.

Next, FIG. 7B shows a state in which the surface oxide film 14 is formed on the surface of the substrate 10 including the inside of the slit 12. The surface oxide film 14 is formed by thermal oxidation by applying a temperature of, for example, about 1100 ° C. to the substrate 10 for a predetermined time after the above-described DRIE processing. Thereby, a surface oxide film (SiO ₂ ) 14 is formed on the surface of the substrate 10 and the inner surface of the slit 12.

[Substrate cleaning step S125: FIG. 7]
Next, with the surface oxide film 14 shown in FIG. 7B formed, the substrate 10 is cleaned using, for example, HPM diluted with ultrapure water by adding hydrochloric acid to hydrogen peroxide water. Thereby, the contamination adhering to the scallop 15 due to the strongly acidic property can be effectively removed.

  Alternatively, by cleaning the substrate 10 using, for example, a hydrofluoric acid solution having a function of dissolving the surface oxide film 14, the surface oxide film 14 is also dissolved and removed as shown in FIG. be able to. Thereby, the contamination taken in the wall surface inside the slit 12 can be effectively removed. Further, as shown in FIG. 7C, the unevenness of the scallop 15 is reduced from s1 to s2 by dissolving and removing the surface oxide film 14. As a result, the flatness of the side surface of the slit 12 can be improved.

[Description of effects]
As described above, since the substrate cleaning process using an acid is performed after the surface oxide film forming process and before the metal film forming process, contamination is more effectively performed without damaging the metal film. Can be removed. Accordingly, it is possible to provide a method for manufacturing a submount that can maintain high cleanliness. In the surface oxide film forming step, thermal oxidation is performed at a high temperature. However, since it is before the metal film forming step, the metal film formation is not particularly affected.

  Further, by performing the cleaning using the hydrofluoric acid solution, it is possible to obtain higher cleanliness and at the same time improve the flatness of the side surface of the submount.

[Description of Third Embodiment: FIG. 8]
Next, a third embodiment will be described with reference to FIG. FIG. 8 corresponds to FIG. 3B used in the description of the first embodiment.

  The feature of the third embodiment is that in forming the slit in the first outer shape forming step, a narrow frame-shaped slit is formed, and a wide slit is formed by removing an island-shaped portion inside the frame-shaped slit. It is to be. Since the basic manufacturing method is the same as that in the first embodiment, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 8A shows a state in which a thin frame-shaped slit is formed by performing a first outer shape forming process in order to form a submount on the substrate 10. FIGS. 8B and 8C are enlarged plan views of a portion C shown in FIG. In FIG. 8B, a slit 11 having a thin frame shape and a width of t <b> 1 is formed so as to penetrate therethrough, and an island-like portion 18 is formed inside the slit 11.

  In dry etching, it is known that a slit having a high squareness is obtained as the width of the slit 11 to be formed is narrow. However, since the minimum opening width of the resist is limited by photolithography, the slit width t1 is, for example, 10 to 10. It is desirable to be about 20 μm.

  By holding the lower surface of the substrate 10 with a dry film (not shown) or the like, the island-like portion 18 in the slit 11 that penetrates can be held so as not to fall off. Next, the resist 10 and the dry film are peeled and removed by immersing the substrate 10 having a plurality of slits 11 in a resist stripping solution.

  At that time, when the island-shaped portion 18 is detached from the substrate 10 together with the dry film, a wide slit 12 having a slit width t2 is formed as shown in FIG. Thereby, even if it is wide, a slit having a higher perpendicularity can be obtained. In the metal film forming step, the metal film can be simultaneously formed on the surface including the side surface of the submount.

[Description of effects]
As described above, by forming a thin frame-shaped slit and removing the island-shaped portion inside the frame-shaped slit, a slit having a higher squareness can be formed, and the wide slit can be The metal film can be simultaneously formed on the side surface and the surface of the mount, and the metal film formation time can be shortened.

10 Substrate (wafer)
11 Thin frame-shaped slit 12 Slit 14 Surface oxide film 15 Scallop (unevenness)
17 Cutting groove 18 Island-shaped portion 20 Submount 20J Upper surface of submount 20J 'Lower surface of submount 20S Side surface of submount (mounting surface to mount object)
20S 'Opposite side surface of submount 20K Side surface adjacent to side surface of submount (machined surface)
Side surface adjacent to the side of the 20K 'submount (machined surface)
21 Underlying metal film 22 Adhesive metal film 23 Metal opening

Claims (10)

In the submount manufacturing method of forming the submount from the substrate,
A first outline forming step of processing the substrate to form at least one surface of the submount;
A substrate cleaning step of cleaning the substrate after the first outer shape forming step;
A metal film forming step of forming a metal film on the surface of the submount cleaned by the substrate cleaning step;
A second outer shape forming step for forming at least one surface of the submount excluding the surface formed in the first outer shape forming step;
A method of manufacturing a submount, comprising:   The method for manufacturing a submount according to claim 1, wherein the substrate cleaning step includes a cleaning step using an acid.   3. The method of manufacturing a submount according to claim 1, wherein the first outer shape forming step is a step of forming at least one surface of the submount by dry etching the substrate.   The method for manufacturing a submount according to any one of claims 1 to 3, further comprising a surface oxide film forming step of forming an oxide film on the surface of the substrate before the substrate cleaning step.   The method for manufacturing a submount according to claim 4, wherein the substrate cleaning step includes a cleaning step using a hydrofluoric acid solution.   The method for manufacturing a submount according to claim 1, wherein the metal film forming step is a step of forming a base metal film layer and an adhesive metal film layer as a metal film in a stacked manner. .   The method of manufacturing a submount according to claim 1, wherein the second outer shape forming step is performed by machining.   The surface of the submount formed by the first outer shape forming step is two opposite surfaces, and the surface formed by the second outer shape forming step is two other opposite surfaces orthogonal to the two opposite surfaces. The method for manufacturing a submount according to claim 1, wherein the submount is provided.   9. The first outer shape forming step forms a wide slit by forming a thin frame-shaped slit and removing an island-shaped portion inside the frame-shaped slit. The manufacturing method of the submount any one of these.   The method for manufacturing a submount according to claim 1, wherein the substrate is a silicon substrate.

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