JP7508918B2 - Solder film and manufacturing method thereof, optical device component, and optical device - Google Patents

Description

The present invention relates to a solder film, and an optical device component and an optical device that use the solder film.

In recent years, optical devices equipped with optical elements such as LDs (Laser Diodes) and LEDs (Light Emitting Diodes) have been used in applications such as displays, projectors, and automobile headlamps. In optical devices, components such as optical elements are fixed to a mounting substrate using a solder film. Known examples of solder films include solder films containing Au and Sn.

For example, the following Patent Document 1 discloses a method of bonding an optical semiconductor element to a mounting substrate using AuSn multilayer solder in which Au layers and Sn layers are alternately laminated. The AuSn multilayer solder of Patent Document 1 has a total of seven laminated Au and Sn layers.

In addition, the following Patent Document 2 discloses a method for forming a solder film containing Au and Sn, in which a deposition source made of alloyed AuSn is heated at a first temperature to selectively evaporate Sn to form a Sn-rich first layer, and then the deposition source is further heated at a second temperature higher than the first temperature to form a Au-rich second layer.

Japanese Patent Application Laid-Open No. 10-006073 JP 2008-263130 A

In optical devices, in addition to optical elements, submounts for mounting optical elements, prisms, and other components may also be mounted, and solder films are often used to bond these components. However, the solder films in Patent Documents 1 and 2 do not have a sufficiently flat surface, and may not be able to sufficiently increase the bonding force (bonding strength) when mounting such components in a package or the like.

The object of the present invention is to provide a solder film that has excellent surface flatness and can effectively increase bonding strength, as well as optical device components and optical devices that use the solder film.

The solder film according to the present invention is a solder film used to fix components in optical devices, and is characterized by having an Au-Sn alloy film, which is a single layer film made of an alloy of Au and Sn.

In the present invention, it is preferable that the Au-Sn alloy film does not have a concentration gradient of Au and Sn in the thickness direction.

In the present invention, it is preferable that the Au-Sn alloy film is a sputtered film formed using a target made of an alloy of Au and Sn.

In the present invention, it is preferable that the crystals in the Au-Sn alloy film are oriented in the thickness direction.

In the present invention, when the total mass of Au in the Au-Sn alloy film is taken as M _A and the total mass of Sn is taken as M _S , it is preferable that the ratio of the mass of Au to the total mass of Au and Sn, M _A /(M _A +M _S ), is 0.60 or more and 0.85 or less.

In the present invention, it is preferable to further include an adhesive film provided between the component and the Au-Sn alloy film. More preferably, the adhesive film has a first layer provided on the component side and containing at least one selected from the group consisting of Cr, Ti, and Ni, a second layer provided on the first layer and containing at least one selected from the group consisting of Ni, Pt, Pd, and Ni-Cr alloys, and a third layer provided on the second layer and containing Pt or Au.

In the present invention, it is preferable that the Au-Sn alloy film further includes an Au film provided on the main surface opposite the component side, the Au film being the outermost layer.

In the present invention, it is preferable that the arithmetic mean roughness Ra of the surface of the solder film is 0.05 μm or less.

In the present invention, it is preferable that the maximum surface height Rz of the solder film is 0.25 μm or less.

In the present invention, it is preferable that the overall thickness of the solder film is 1 μm or more and 15 μm or less.

The optical device component according to the present invention is characterized by comprising a component body having a main surface, and a solder film configured according to the present invention provided on the main surface of the component body.

In the present invention, it is preferable that the optical device part is at least one selected from the group consisting of a prism, an optical element, a submount for mounting the optical element, and a packaging member for mounting the optical element.

The optical device according to the present invention comprises a prism, an optical element that emits light to the prism or receives light from the prism, a package in which the prism and the optical element are mounted, and a submount that is provided between the optical element and the package, and is characterized in that the prism and the package are bonded together, the optical element and the submount are bonded together, the submount and the package are bonded together, or the components that make up the package are bonded together, by a solder film configured according to the present invention.

The present invention provides a solder film that has excellent surface flatness and can effectively increase bonding strength, as well as optical device components and optical devices that use the solder film.

1 is a schematic cross-sectional view showing a solder film and an optical device component according to a first embodiment of the present invention. 2 is a schematic cross-sectional view showing an enlarged view of a portion where a solder film is provided according to the first embodiment of the present invention; FIG. FIG. 11 is a schematic cross-sectional view showing an enlarged view of a portion where a solder film is provided according to a second embodiment of the present invention. 1 is a schematic cross-sectional view showing an optical device according to an embodiment of the present invention. 1A to 1C are schematic diagrams for explaining film-coated substrates produced in Examples and Comparative Examples. 2 is a SEM photograph showing a cross section of the solder film obtained in Example 1.

The following describes preferred embodiments. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[Solder film and optical device parts]
First Embodiment
Fig. 1 is a schematic cross-sectional view showing a solder film and an optical device component according to a first embodiment of the present invention, and Fig. 2 is a schematic cross-sectional view showing an enlarged view of a portion where the solder film according to the first embodiment of the present invention is provided.

The prism 10 is an optical device component used in an optical device. The prism 10 comprises a prism body 11, a solder film 1, and a reflective film 12.

The prism body 11 has a substantially trapezoidal cross-sectional shape. The prism body 11 has a bottom surface 11a, a slope 11b connected to the bottom surface 11a, and an upper surface 11c facing the bottom surface 11a and connected to the slope 11b. The cross-sectional shape of the prism body 11 is not particularly limited, and may be substantially triangular, for example. In this embodiment, the prism body 11 is made of an appropriate glass material.

A reflective film 12 is provided on the inclined surface 11b of the prism body 11. The reflective film 12 is, for example, a dielectric multilayer film in which high-refractive-index films and low-refractive-index films are alternately laminated. Examples of the material of the high-refractive-index film include TiO ₂ , Ta ₂ O ₅ , ZrO ₂ , and HfO ₂ . Examples of the material of the low-refractive-index film include SiO ₂ and MgF ₂ . The reflective film 12 may be a single-layer metal film, and is not particularly limited. In addition, the reflective film 12 may be provided on at least a part of the inclined surface 11b of the prism body 11, and may be provided on the entire surface of the inclined surface 11b, for example. By providing the reflective film 12 on the inclined surface 11b, the light emitted from the light source can be suitably reflected. However, the reflective film 12 may not be provided. The reflective film 12 can be formed by stacking each layer by, for example, a sputtering method or a vacuum deposition method.

A solder film 1 is provided on the bottom surface 11a of the prism body 11. The prism 10, which is an optical device component, is fixed to a package, a mounting board, or the like by the solder film 1. It is preferable that the solder film 1 is provided on the entire bottom surface 11a of the prism body 11, but it is sufficient that the solder film 1 is provided on at least a portion of the bottom surface 11a of the prism body 11. The solder film 1 may also wrap around the side surface of the prism body 11. In that case, the bonding strength provided by the solder film 1 can be further increased.

As shown in FIG. 2, the solder film 1 is composed of an Au-Sn alloy film 2. The Au-Sn alloy film 2 is a single layer film made of an alloy of Au and Sn.

The Au-Sn alloy film 2 has a first main surface 2a and a second main surface 2b that face each other. The first main surface 2a is the main surface on the prism body 11 side. The second main surface 2b is the outer main surface on the opposite side to the prism body 11. The direction connecting the first main surface 2a and the second main surface 2b is the thickness direction of the solder film 1. In this embodiment, the first main surface 2a of the Au-Sn alloy film 2 is in contact with the prism body 11.

The solder film 1 of this embodiment has an Au-Sn alloy film 2, which is a single layer film made of an alloy of Au and Sn, and therefore has excellent surface flatness. In addition, when mounting the prism 10, which is an optical device component, in a package or the like, the bonding strength can be effectively increased. This can be explained as follows.

Conventionally, in solder films made of alternating layers of Au and Sn, the Sn layers could undergo crystal growth when exposed to thermal energy, or could become rough on the film surface due to oxidation.

In contrast, the solder film 1 of this embodiment is composed of the Au-Sn alloy film 2, which is a single layer film made of an alloy of Au and Sn. This makes it difficult for Sn to grow crystals on its own, and reduces the effects of crystal growth and oxidation caused by thermal energy, resulting in a flatter film surface 1a. Therefore, the solder film 1 can increase the bonding strength when mounting the prism 10, which is an optical device component, on a package or the like.

In this embodiment, the Au-Sn alloy film 2 is preferably an alloy layer containing 95% by mass or more of Au and Sn. Depending on the degree of purification of Au and Sn, impurities such as Fe, Cr, Ni, etc. may be mixed into the alloy layer. In this case, it has been confirmed that the effect of the present invention is not impaired if the content of Au and Sn is 95% by mass or more.

It is also preferable that the Au-Sn alloy film 2 does not have a concentration gradient of Au and Sn in the thickness direction. In this case, since the melting point is unlikely to fluctuate, the solder film 1 can be made less likely to flow by controlling it at a specific temperature or lower. Furthermore, when manufacturing optical devices, they can be manufactured stably under certain manufacturing conditions, which improves yield and increases productivity. In addition, the bonding strength of the solder film 1 can be increased even more effectively.

In this specification, the Au-Sn alloy film 2 does not have a concentration gradient of Au means that the absolute value of the difference between the Au concentration (mass ratio to the entire metal) on the first main surface 2a side of the Au-Sn alloy film 2 and the Au concentration (mass ratio to the entire metal) on the second main surface 2b side of the Au-Sn alloy film 2 is 5% or less. However, the absolute value of the difference between the Au concentration (mass ratio to the entire metal) on the first main surface 2a side of the Au-Sn alloy film 2 and the Au concentration (mass ratio to the entire metal) on the second main surface 2b side of the Au-Sn alloy film 2 is preferably 3% or less, and more preferably 1% or less.

The Au-Sn alloy film 2 does not have a Sn concentration gradient when the absolute value of the difference between the Sn concentration (mass ratio to the entire metal) on the first main surface 2a side of the Au-Sn alloy film 2 and the Sn concentration (mass ratio to the entire metal) on the second main surface 2b side of the Au-Sn alloy film 2 is 5% or less. However, the absolute value of the difference between the Sn concentration (mass ratio to the entire metal) on the first main surface 2a side of the Au-Sn alloy film 2 and the Sn concentration (mass ratio to the entire metal) on the second main surface 2b side of the Au-Sn alloy film 2 is preferably 3% or less, and more preferably 1% or less.

In this specification, the Au or Sn concentration on the first main surface 2a side of the Au-Sn alloy film 2 refers to the Au or Sn concentration in a portion of the Au-Sn alloy film 2 that is 10% thick from the first main surface 2a. The Au or Sn concentration on the second main surface 2b side of the Au-Sn alloy film 2 refers to the Au or Sn concentration in a portion of the Au-Sn alloy film 2 that is 10% thick from the second main surface 2b. The Au or Sn concentration on each main surface side of the Au-Sn alloy film 2 can be measured, for example, by SEM-EDX.

In this embodiment, when the total mass of Au in the Au-Sn alloy film 2 is M _A and the total mass of Sn is M _S , the ratio of the mass of Au to the total mass of Au and Sn, M _A /(M _A +M _S ), is preferably 0.60 or more, more preferably 0.70 or more, preferably 0.85 or less, more preferably 0.82 or less. In this case, the melting points (eutectic temperatures) of Au and Sn can be brought closer to the minimum value of 280° C., and bonding can be performed at a lower temperature when mounting on a package or the like.

In this embodiment, it is preferable that the crystals are oriented in the thickness direction in the Au-Sn alloy film 2. In this case, when mounting on a package or the like, bonding can be performed more quickly and reliably. Note that the crystals in the Au-Sn alloy film 2 may be oriented in a direction other than the thickness direction. Note that the crystals referred to in this invention refer to crystals formed with a weight ratio of Au9Sn1 and Au6Sn4. To obtain an Au-Sn alloy film 2 with oriented crystals, the film formation conditions of the sputtering can be adjusted, for example, by increasing the amount of power between the substrate and the target or by lowering the film formation pressure.

In this embodiment, the thickness of the Au-Sn alloy film 2 is preferably 1 μm or more, more preferably 3 μm or more, preferably 10 μm or less, and more preferably 6 μm or less. When the thickness of the Au-Sn alloy film 2 is equal to or greater than the above lower limit, the bonding strength of the solder film 1 can be further increased when mounting the film on a package or the like. When the thickness of the Au-Sn alloy film 2 is equal to or less than the above upper limit, warping due to film stress can be further suppressed. In addition, when mounting the film on a package or the like, the film can be reliably bonded in a shorter time.

In this embodiment, the total thickness of the solder film 1 is not particularly limited, but is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 4 μm or more, preferably 15 μm or less, and more preferably 7 μm or less. When the total thickness of the solder film 1 is equal to or greater than the above lower limit, the bonding strength of the solder film 1 can be further increased when mounting the solder film 1 on a package or the like. On the other hand, when the total thickness of the solder film 1 is equal to or less than the above upper limit, warping due to film stress can be further suppressed. In addition, when mounting the solder film 1, the solder film 1 can be reliably bonded in a shorter time. Furthermore, in this case, the positional deviation of the prism body 11 in the height direction is reduced, so that the positional accuracy of the prism 10, which is a component for an optical device, can be further effectively improved.

In this embodiment, the arithmetic mean roughness Ra of the film surface 1a of the solder film 1 is preferably 0.05 μm or less, more preferably 0.03 μm or less. When the arithmetic mean roughness Ra of the film surface 1a of the solder film 1 is equal to or less than the upper limit value, the adhesion between the solder film 1 and a package or the like can be further improved, and the bonding strength of the solder film 1 can be further increased. The lower limit of the arithmetic mean roughness Ra of the film surface 1a of the solder film 1 is not particularly limited, but can be, for example, 0.01 μm. The arithmetic mean roughness Ra can be measured in accordance with JIS B 0601:2013.

In this embodiment, the maximum height Rz of the solder film 1 on the film surface 1a is preferably 0.25 μm or less, more preferably 0.15 μm or less. When the maximum height Rz of the solder film 1 on the film surface 1a is equal to or less than the above upper limit, the adhesion between the solder film 1 and a package or the like can be further improved, and the bonding strength of the solder film 1 can be further increased. The lower limit of the maximum height Rz of the solder film 1 on the film surface 1a is not particularly limited, but can be, for example, 0.01 μm. The maximum height Rz can be measured in accordance with JIS B 0601:2013.

The Au-Sn alloy film 2 that constitutes the solder film 1 can be produced, for example, by forming the film using a sputtering method using a target made of an Au-Sn alloy.

During sputtering, an inert gas such as argon gas can be used as the carrier gas. The deposition temperature can be, for example, 30°C or higher and 250°C or lower. The power between the substrate and the target can be, for example, 500 W or higher and 1500 W or lower, and the deposition pressure can be, for example, 0.1 Pa or higher and 3.0 Pa or lower.

The sputtering method allows deposition while maintaining the mass ratio of the target made of an Au-Sn alloy, so it is possible to deposit an Au-Sn alloy film 2 that does not have a concentration gradient of Au and Sn. Furthermore, if produced under the above manufacturing conditions, it is possible to deposit an Au-Sn alloy film 2 in which the crystals are oriented in the thickness direction.

Second Embodiment
FIG. 3 is a schematic cross-sectional view showing, in an enlarged manner, a portion where a solder film is provided according to a second embodiment of the present invention.

As shown in FIG. 3, the solder film 21 further has an adhesion film 23. The adhesion film 23 is provided between the prism body 11 and the Au-Sn alloy film 2. Therefore, in the solder film 21, the Au-Sn alloy film 2 is laminated on top of the adhesion film 23. By providing the adhesion film 23, it is possible to improve adhesion with the prism body 11.

The adhesion film 23 has a first layer 23a, a second layer 23b, and a third layer 23c. The first layer 23a is the layer on the prism body 11 side. The second layer 23b is laminated on the first layer 23a. The third layer 23c is laminated on the second layer 23b. The third layer 23c is the layer on the Au-Sn alloy film 2 side.

The material constituting the first layer 23a may be, for example, Ni, Cr, Ti, W, TiW, Mo, or a Ni-Cr alloy. Of these, Cr, Ti, or Ni is preferable. These materials may be used alone or in combination. It is preferable that the material constituting the first layer 23a contains 95% or more of the above-mentioned materials. However, the first layer 23a may contain impurities or additives as long as they do not impair the effects of the present invention.

The thickness of the first layer 23a is not particularly limited, but can be, for example, 0.05 μm or more and 1.0 μm or less. The first layer 23a can be formed by an appropriate method such as plating, vapor deposition, or sputtering.

The material constituting the second layer 23b may be, for example, Ni, Pt, Pd, or a Ni-Cr alloy. Among these, Ni, Pt, Pd, or a Ni-Cr alloy is preferable. These materials may be used alone or in combination. It is preferable that the material constituting the second layer 23b contains 95% or more of the above-mentioned materials. However, the second layer 23b may contain impurities or additives as long as they do not impair the effects of the present invention.

The thickness of the second layer 23b is not particularly limited, but can be, for example, 0.05 μm or more and 2.0 μm or less. The second layer 23b can be formed by an appropriate method such as plating, vapor deposition, or sputtering. The second layer 23b does not have to be provided in the adhesion film 23.

The third layer 23c preferably functions as a diffusion prevention layer. For example, it is desirable for it to be a layer for preventing the components of the Au-Sn alloy film 2 from diffusing into the first layer 23a and the second layer 23b. This can further increase the bonding strength of the solder film 21 to the package, etc.

The third layer 23c is not particularly limited, but in this embodiment, it is Pt. In this case, it is possible to further suppress the components of the Au-Sn alloy film 2 from diffusing into the first layer 23a and the second layer 23b. However, the material of the third layer 23c is not limited to Pt, and may be Au, Pd, etc. These materials may be used alone or in combination. It is preferable that the third layer 23c contains 95% or more of the materials exemplified above. However, the third layer 23c may contain impurities and additives to the extent that they do not impair adhesion.

The thickness of the third layer 23c is not particularly limited, but can be, for example, 0.05 μm or more and 1.0 μm or less.

The solder film 21 further includes an Au film 24. The Au film 24 is laminated on the second main surface 2b of the Au-Sn alloy film 2. The Au film 24 is provided as the outermost layer of the solder film 21.

It is preferable that the Au film 24 contains 95% or more Au. However, the Au film 24 may contain impurities or additives as long as they do not impair adhesion. Other points are the same as those of the first embodiment.

As with the solder film 21 in the second embodiment, an adhesion film 23 may be further provided. Also, an Au film 24 may be provided on the outermost layer. When the outermost layer is the Au film 24, the outermost layer that contacts the package or the like can be made less susceptible to oxidation during mounting, and the bonding strength of the solder film 21 can be more reliably increased.

Also, in the second embodiment, the solder film 21 is provided with the Au-Sn alloy film 2, which is a single layer film made of an alloy of Au and Sn, and therefore has excellent surface flatness, and can increase the bonding strength when the prism 20, which is an optical device component, is mounted in a package or the like.

In the first and second embodiments, the prisms 10 and 20 are described as optical device components. However, in the present invention, the optical device components may be optical elements, submounts for mounting optical elements, or packaging members for mounting optical elements.

[Optical Devices]
Fig. 4 is a schematic cross-sectional view showing an optical device according to an embodiment of the present invention. As shown in Fig. 4, an optical device 31 includes an optical element 32, a submount 33, a prism 10, and a package 34. The optical element 32, the submount 33, and the prism 10 are housed in the package 34.

More specifically, the package 34 is a container-shaped member having a bottom 35 and a side wall 36 disposed on the bottom 35. The package 34 can be made of, for example, a ceramic material. Examples of the ceramic material that can be used include alumina and aluminum nitride. Among these, aluminum nitride is preferable from the viewpoint of further improving heat dissipation.

The bottom 35 has a mounting surface 35a. The sidewall 36 has an inner surface 36a. A metal film 38 is provided on the mounting surface 35a of the bottom 35 and the inner surface 36a of the sidewall 36.

In this embodiment, the optical element 32 and the prism 10 are disposed on the metal film 38 on the mounting surface 35a. More specifically, a submount 33 is provided on the metal film 38, and the optical element 32 is disposed on the submount 33. At this time, one main surface 33a of the submount 33 is bonded to the optical element 32 by a solder film 1 (not shown). In addition, the other main surface 33b of the submount 33 is bonded to the metal film 38 by a solder film 1 (not shown). In addition, the prism 10 is also bonded to the metal film 38 by the solder film 1.

The package 34 does not necessarily have to have the metal film 38. However, it is preferable that the package 34 has the metal film 38 as in this embodiment. This configuration is particularly effective when the difference in thermal expansion coefficient between the submount 33 or prism 10 and the package 34 is relatively large.

The metal film 38 is preferably an Au film. In this case, since the metal film 38 is not easily oxidized, the bonding strength between the submount 33 and the prism 10 and the package 34 can be further increased during the manufacture of the optical device 31.

In this embodiment, the metal film 38 is provided on the entire mounting surface 35a of the bottom 35 and the entire inner surface 36a of the sidewall 36. However, it is sufficient that the metal film 38 is provided at least on the portion where the submount 33 and the prism 10 are disposed.

A lid 37 is provided on the side wall 36 of the package 34 to seal the optical element 32 and the prism 10. The lid 37 is not particularly limited, but in this embodiment it is a glass lid. The lid 37 and the side wall 36 are joined by a solder film 1 (not shown). In this case, no gas is generated after joining, so impurities are less likely to adhere to the reflective film 12 of the prism 10, and deterioration of the reflection characteristics is less likely to occur.

In this embodiment, the optical element 32 is a light source that emits light to the prism 10. The light source is not particularly limited, but may be, for example, an LD or an LED. As shown in FIG. 4, light A emitted from the optical element 32 is reflected by the prism 10, passes through the cover 37, and is emitted outside the optical device 31. The optical element 32 may be a light receiving element that receives light from the prism 10.

The submount 33 is provided for mounting the optical element 32. The submount 33 also serves as a heat sink. Therefore, heat generated by the optical element 32 can be efficiently dissipated to the package 34 side through the submount 33.

In the optical device 31, the solder film 1 bonds the prism 10 and the package 34, bonds the optical element 32 and the submount 33, bonds the submount 33 and the package 34, and bonds the lid 37 and the sidewall 36 of the package 34. Therefore, the bonding strength between the various components in the optical device 31 is increased. This increases the reliability of the optical device 31.

In addition, in the optical device 31, the lid 37 and sidewall 36 of the package 34 may be joined by a solder film with a low melting point, such as Sn-Ag. In this case, if the other components are joined by a solder film 1 with a higher melting point than the solder film, the optical element 32, submount 33, and prism 10 are less likely to be misaligned in the height direction due to heating when joining the lid 37 and sidewall 36 with the solder film after mounting the optical element 32, submount 33, and prism 10. This further increases the reliability of the optical device 31.

The temperature at which the optical element 32, submount 33, and prism 10 are bonded can be, for example, 290°C to 320°C. The temperature at which the lid 37 and side wall 36 are bonded can be 220°C to 270°C. Bonding within such a temperature range can further improve the positional accuracy of the optical element 32, submount 33, and prism 10 in the height direction.

In the present invention, at least one of the bonding of the components constituting the optical element 32, the submount 33, the prism 10, and the package 34 may be performed by the solder film 1, and there is no particular limitation.

The present invention will be described in more detail below based on specific examples. The present invention is not limited to the following examples, and can be modified as appropriate within the scope of the gist of the invention.

Example 1
First, a target made of an Au-Sn alloy was used to form an Au-Sn alloy film, which is a single layer made of an alloy of Au and Sn, on a glass substrate 42 (manufactured by Nippon Electric Glass Co., Ltd., OA-10G, thickness: 0.197 mm) shown in FIG. 5 by a sputtering method, to obtain a solder film 41. In addition, the mass ratio of Au to Sn in the target during sputtering was 70:30. Argon (Ar) gas was used as the carrier gas, and the film formation temperature was approximately 100° C. due to the kinetic energy of the sputtering during film formation with the heater OFF. In addition, the thickness of the obtained Au-Sn alloy film was 5 μm.

Figure 6 is an SEM photograph showing a cross section of the solder film 41 obtained in Example 1. From Figure 6, it can be seen that the crystals are oriented in the thickness direction in the solder film 41 obtained in Example 1. It has also been confirmed that the solder film 41 does not have a concentration gradient of Au and Sn.

(Comparative Example 1)
A total of 180 Au layers and Sn layers were alternately laminated by vapor deposition on a glass substrate 42 (OA-10G, manufactured by Nippon Electric Glass Co., Ltd., thickness: 0.197 mm) to obtain a solder film 41. The thickness of each Au layer was 25.6 nm, and the thickness of each Sn layer was 29.4 nm. The overall thickness of the solder film 41 was 5 μm.

[evaluation]
(Evaluation of surface flatness)
The arithmetic mean roughness Ra and maximum height Rz of the film surface 40a of the film-coated substrate 40 were measured in accordance with JIS B 0601:2013.

(Evaluation of Adhesion)
In the evaluation of adhesion, an aluminum nitride substrate having a gold-plated portion was prepared as a package. Next, the film-coated substrate 40 was attached to the gold-plated portion of the aluminum nitride substrate from the solder film 41 side, and bonded by heating to 320° C. in a nitrogen atmosphere.

Next, the adhesion strength was evaluated by pressing the film-coated substrate 40 from the side using a tension-compression tester (SV-201, manufactured by Imada Seisakusho Co., Ltd.). The adhesion strength was evaluated under the condition of a bonding time of 10 seconds.

The results are shown in Table 1 below.

As is clear from Table 1, the solder film 41 of Example 1, which uses an Au-Sn alloy film, a single layer film made of an alloy of Au and Sn, was confirmed to have excellent surface flatness and excellent bonding strength with the package.

DESCRIPTION OF SYMBOLS 1, 21, 41...Solder film 1a, 21a, 40a...Film surface 2...Au-Sn alloy film 2a...First main surface 2b...Second main surface 10, 20...Prism 11...Prism body 11a...Bottom surface 11b...Slope 11c...Top surface 12...Reflective film 23...Adhesion film 23a...First layer 23b...Second layer 23c...Third layer 24...Au film 31...Optical device 32...Optical element 33...Submount 33a...One side main surface 33b...Other side main surface 34...Package 35...Bottom 35a...Mounting surface 36...Side wall portion 36a...Inner surface 37...Cover 38...Metal film 40...Film-coated substrate 42...Glass substrate

Claims (13)

A solder film used to fix components in an optical device, comprising:
The substrate is provided with an Au-Sn alloy film, which is a single layer film made of an alloy of Au and Sn;
The Au—Sn alloy film contains 95 mass % or more of Au and Sn,
The Au—Sn alloy film does not have a concentration gradient of Au and Sn in a thickness direction,
The solder film has crystals oriented in the thickness direction of the Au--Sn alloy film . 2. The solder film according to claim 1, wherein, when the total mass of Au in the Au-Sn alloy film is _MA and the total mass of Sn is _MS , a ratio of the mass of Au to the total mass of Au and Sn, _MA /( _MA + _MS ), is 0.60 or more and 0.85 or less. 3. The solder film according to claim 1, further comprising an adhesion film provided between said component and said Au--Sn alloy film. The adhesive film is
A first layer is provided on the component side and contains at least one selected from the group consisting of Cr, Ti, and Ni;
a second layer provided on the first layer and including at least one selected from the group consisting of Ni, Pt, Pd, and a Ni-Cr alloy;
a third layer disposed on the second layer, the third layer including Pt or Au;
The solder film of claim 3 , comprising: The solder film according to any one of claims 1 to 4 , further comprising an Au film provided on a main surface of the Au-Sn alloy film opposite to the component side, the Au film being an outermost layer. The solder film according to claim 1 , wherein the arithmetic mean roughness Ra of the surface of the solder film opposite to the component side is 0.05 μm or less. The solder film according to claim 1 , wherein a maximum height Rz of the surface of the solder film opposite to the component side is 0.25 μm or less. The solder film according to any one of claims 1 to 7 , wherein the entire solder film has a thickness of 1 µm or more and 15 µm or less. A method for manufacturing a solder film used to fix components in an optical device, comprising the steps of:
The method includes a step of forming an Au-Sn alloy film, which is a single layer film made of an alloy of Au and Sn, by a sputtering method using a target made of an alloy of Au and Sn, to obtain a solder film including the Au-Sn alloy film;
The method for producing a solder film, wherein the Au-Sn alloy film contains 95 mass % or more of Au and Sn. 10. The method for producing a solder film according to claim 9, wherein when the Au-Sn alloy film is formed by the sputtering method, argon gas is used as a carrier gas and the film formation temperature is 30° C. or more and 250° C. or less. A component body having a main surface;
The solder film according to any one of claims 1 to 8 provided on the main surface of the component body;
A component for an optical device comprising: 12. The optical device part according to claim 11 , which is at least one selected from the group consisting of a prism, an optical element, a submount for mounting the optical element, and a packaging member for mounting the optical element. A prism and
an optical element that emits light to the prism or receives light from the prism;
a package in which the prism and the optical element are mounted;
a submount provided between the optical element and the package; and
Equipped with
An optical device, wherein the solder film according to any one of claims 1 to 8 bonds the prism and the package when the component is the prism , bonds the optical element and the submount when the component is the optical element, or bonds the submount and the package when the component is a submount .

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