JP2022021508A - Solder film, component for optical device, and optical device - Google Patents

Abstract

To provide a solder film having an excellent surface smoothness and capable of effectively enhancing a bonding force.SOLUTION: A solder film 1 used for fixing a component 10 in an optical device includes an Au-Sn alloy film which is a single layer film composed of an alloy of Au and Sn. The Au-Sn alloy film preferably has no concentration gradient of Au and Sn in a thickness direction, and the Au-Sn alloy film is preferably a sputtered film deposited using a target composed of Au and Sn alloy. Furthermore, when a total mass of Au is MA and a total mass of Sn is MS in the Au-Sn alloy film, a ratio of a mass of Au to a total mass of Au and Sn, MA/(MA+MS), is preferably 0.60 or more and 0.85 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solder film, and an optical device component and an optical device using 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 an optical device, components such as optical elements are fixed to a mounting substrate using a solder film. As the solder film, for example, a solder film containing Au and Sn is known.

For example, Patent Document 1 below discloses a method of bonding an optical semiconductor element onto a mounting substrate by using AuSn multilayer solder in which Au layers and Sn layers are alternately laminated. In the AuSn multilayer solder of Patent Document 1, a total of 7 Au layers and Sn layers are laminated.

Further, in Patent Document 2 below, as a method of forming a solder film containing Au and Sn, a vapor deposition source made of alloyed AuSn is heated at a first temperature to selectively evaporate Sn to be Sn-rich. Disclosed is a method of forming an Au-rich second layer by further heating the vapor deposition source at a second temperature higher than the first temperature after forming the first layer.

Japanese Unexamined Patent Publication No. 10-006073 Japanese Unexamined Patent Publication No. 2008-263130

In an optical device, in addition to an optical element, a submount for mounting the optical element, a component such as a prism, and the like may be mounted, and a solder film is often used for joining these. However, the surface of the solder film as in Patent Document 1 and Patent Document 2 is not sufficiently flat, and the bonding force (bonding strength) cannot be sufficiently increased when the above-mentioned parts are mounted on a package or the like. In some cases.

An object of the present invention is to provide a solder film which is excellent in surface flatness and can effectively enhance a bonding force, and an optical device component and an optical device using the solder film.

The solder film according to the present invention is a solder film used for fixing a component in an optical device, and is characterized by including 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 sputter film formed by using a target made of an alloy of Au and Sn.

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

In the present invention, when the total mass of Au in the Au _— Sn alloy film is MA and the total mass of Sn is MS, the ratio of the mass of Au to the total mass of Au and _Sn is _MA . / ( _MA + MS) is preferably _0.60 or more and 0.85 or less.

In the present invention, it is preferable to further provide an adhesive film provided between the component and the Au—Sn alloy film. The adhesive film is provided on the component side, and is provided on a first layer and the first layer, which comprises at least one selected from the group consisting of Cr, Ti, and Ni. A second layer comprising, at least one selected from the group consisting of Ni, Pt, Pd, and Ni—Cr alloys, and a second layer provided on the second layer comprising Pt or Au. It is more preferable to have three layers.

In the present invention, it is preferable that the Au—Sn alloy film is further provided with an Au film provided on the main surface opposite to the component side, and the Au film is 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, the maximum height Rz of the surface of the solder film is preferably 0.25 μm or less.

In the present invention, the thickness of the entire solder film is preferably 1 μm or more and 15 μm or less.

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

In the present invention, the component for an optical device is at least one selected from the group consisting of a prism, an optical element, a submount for mounting the optical element, and a package member for mounting the optical element. Is preferable.

The optical device according to the present invention includes a prism, an optical element that emits light to the prism or receives light from the prism, a package on which the prism and the optical element are mounted, the optical element, and the optical element. The prism and the package are joined, the optical element and the submount are joined, and the submount is provided by a solder film provided between the packages, which comprises a submount and is configured according to the present invention. The package is joined to each other, or the members constituting the package are joined to each other.

According to the present invention, it is possible to provide a solder film which is excellent in surface flatness and can effectively enhance a bonding force, and an optical device component and an optical device using the solder film.

It is a schematic sectional drawing which shows the solder film and the component for an optical device which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing which enlarges and shows the part where the solder film which concerns on 1st Embodiment of this invention is provided. It is a schematic sectional drawing which enlarges and shows the part where the solder film which concerns on 2nd Embodiment of this invention is provided. It is a schematic sectional drawing which shows the optical device which concerns on one Embodiment of this invention. It is a schematic diagram for demonstrating the substrate with a film produced in an Example and a comparative example. It is an SEM photograph which shows the cross section of the solder film obtained in Example 1. FIG.

Hereinafter, preferred embodiments will be described. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Further, in each drawing, members having substantially the same function may be referred to by the same reference numeral.

[Solder film and parts for optical devices]
(First Embodiment)
FIG. 1 is a schematic cross-sectional view showing a solder film and a component for an optical device according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing an enlarged portion of a portion provided with the solder film according to the first embodiment of the present invention.

The prism 10 is an optical device component used in an optical device. The prism 10 includes 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 main 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 a substantially triangular shape or the like. Further, in the present embodiment, the prism main body 11 is made of an appropriate glass material.

A reflective film 12 is provided on the slope 11b of the prism body 11. The reflective film 12 is composed of, 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 , or HfO ₂ . Examples of the material of the low refractive index film include SiO ₂ or MgF ₂ . The reflective film 12 may be a single-layer metal film and is not particularly limited. Further, the reflective film 12 may be provided on at least a part of the slope 11b of the prism main body 11, and may be provided on the entire surface of the slope 11b, for example. By providing the reflective film 12 on the slope 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 laminating each layer by, for example, a sputtering method, a vacuum vapor deposition method, or the like.

Further, a solder film 1 is provided on the bottom surface 11a of the prism main body 11. The prism 10, which is a component for an optical device, is fixed to a package, a mounting substrate, or the like by a solder film 1. The solder film 1 is preferably provided on the entire bottom surface 11a of the prism body 11, but may be provided on at least a part of the bottom surface 11a of the prism body 11. Further, the solder film 1 may wrap around the side surface of the prism main body 11. In that case, the bonding force of 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 facing each other. The first main surface 2a is the main surface on the prism body 11 side. The second main surface 2b is an outer main surface opposite 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 the present embodiment, the first main surface 2a of the Au—Sn alloy film 2 is in contact with the prism body 11.

Since the solder film 1 of the present embodiment includes the Au—Sn alloy film 2, which is a single-layer film made of an alloy of Au and Sn, the surface is excellent in flatness. Further, when the prism 10 which is a component for an optical device is mounted on a package or the like, the bonding force can be effectively increased. This point can be explained as follows.

Conventionally, in a solder film in which Au layers and Sn layers are alternately laminated, the Sn layer may receive thermal energy to grow crystals, or the film surface may be roughened due to the influence of oxidation. ..

On the other hand, since the solder film 1 of the present embodiment is composed of the Au—Sn alloy film 2 which is a single-layer film made of an alloy of Au and Sn, it is difficult for Sn to grow independently and heat. The influence of crystal growth and oxidation due to energy can be reduced, and as a result, the film surface 1a can be made flatter. Therefore, in the solder film 1, the bonding force can be increased when the prism 10, which is a component for an optical device, is mounted on a package or the like.

In the present 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, and Ni may be mixed in the alloy layer. In this case, it has been confirmed that if the contents of Au and Sn are 95% by mass or more, the effect of the present invention is not impaired.

Further, it is 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 difficult to flow by controlling the temperature below a specific temperature. Further, when the optical device is manufactured, it can be stably manufactured under certain manufacturing conditions, so that the yield can be improved and the productivity can be improved. In addition, the bonding force of the solder film 1 can be further effectively increased.

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

Further, the fact that the Au—Sn alloy film 2 does not have a Sn concentration gradient means that the concentration of Sn on the first main surface 2a side of the Au—Sn alloy film 2 (mass ratio to the entire metal) and the second. It is assumed that the absolute value of the difference from the concentration of Sn on the main surface 2b side (mass ratio to the whole metal) is 5% or less. However, in the Au—Sn alloy film 2, the concentration of Sn on the first main surface 2a side (mass ratio to the entire metal) and the concentration of Sn on the second main surface 2b side (mass ratio to the entire metal) The absolute value of the difference is preferably 3% or less, more preferably 1% or less.

Further, in the present specification, the concentration of Au or Sn on the first main surface 2a side of the Au—Sn alloy film 2 is a thickness portion of the Au—Sn alloy film 2 that is 10% from the first main surface 2a. Au or Sn concentration. Further, the concentration of Au or Sn on the second main surface 2b side of the Au—Sn alloy film 2 is the concentration of Au or Sn in the portion of the Au—Sn alloy film 2 having a thickness of 10% from the second main surface 2b. It shall refer to the concentration. Further, the concentration of Au or Sn on each main surface side of the Au—Sn alloy film 2 can be measured by, for example, SEM-EDX.

In the present embodiment, when the total mass of Au in the Au _— Sn alloy film 2 is MA and the total mass of Sn is MS, the ratio of the mass of Au to the total mass of Au and _Sn is _MA . / ( _MA + MS) is preferably _0.60 or more, more preferably 0.70 or more, preferably 0.85 or less, and more preferably 0.82 or less. In this case, the melting points (eutectic temperature) of Au and Sn can be brought closer to the minimum value of 280 ° C., and the bonding can be performed at a lower temperature when mounted on a package or the like.

In the present 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, it is possible to reliably join in a shorter time. In the Au—Sn alloy film 2, the crystals may be oriented in a direction other than the thickness direction. The crystal referred to in the present invention means a crystal formed by the component ratio of Au9Sn1 and the component ratio of Au6Sn4 in terms of weight ratio. In order to obtain the Au—Sn alloy film 2 in which the crystals are oriented, the film forming conditions of sputtering may be adjusted, for example, the electric energy between the substrate and the target may be increased, or the film forming pressure may be lowered.

In the present 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 value, the bonding force of the solder film 1 can be further increased when mounted on a package or the like. When the thickness of the Au—Sn alloy film 2 is not more than the above upper limit value, warpage due to film stress can be further suppressed. In addition, when it is mounted on a package or the like, it can be reliably joined in a shorter time.

In the present embodiment, the overall thickness of the solder film 1 is not particularly limited, but is preferably 1 μm or more, more preferably 2 μm or more, still 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 at least the above lower limit value, the bonding force of the solder film 1 can be further increased when mounted on a package or the like. On the other hand, when the total thickness of the solder film 1 is not more than the above upper limit value, warpage due to film stress can be further suppressed. In addition, when mounting, it is possible to reliably join in a shorter time. Further, in this case, since the positional deviation of the prism body 11 in the height direction becomes small, the positional accuracy of the prism 10 which is a component for an optical device can be further effectively improved.

In the present embodiment, the arithmetic mean roughness Ra on 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 on the film surface 1a of the solder film 1 is not more than the above upper limit value, the adhesion between the solder film 1 and the package or the like can be further enhanced, and the bonding force by the solder film 1 is further enhanced. be able to. The lower limit of the arithmetic mean roughness Ra on the film surface 1a of the solder film 1 is not particularly limited, but may be, for example, 0.01 μm. Further, the arithmetic mean roughness Ra can be measured according to JIS B 0601: 2013.

In the present 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 value, the adhesion between the solder film 1 and the package or the like can be further enhanced, and the bonding force of the solder film 1 can be further enhanced. Can be done. The lower limit of the maximum height Rz of the solder film 1 on the film surface 1a is not particularly limited, but may be, for example, 0.01 μm. Further, the maximum height Rz can be measured according to JIS B 0601: 2013.

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

For sputtering, an inert gas such as argon gas can be used as the carrier gas. Further, the film formation temperature can be, for example, 30 ° C. or higher and 250 ° C. or lower. Further, the amount of electric power between the substrate and the target can be, for example, 500 W or more and 1500 W or less, and the film forming pressure can be, for example, 0.1 Pa or more and 3.0 Pa or less.

In the sputtering method, since the film can be formed while maintaining the mass ratio of the target made of the Au—Sn alloy, the Au—Sn alloy film 2 having no concentration gradient of Au and Sn can be formed. .. Further, if it is manufactured under the above-mentioned manufacturing conditions, it is possible to form an Au—Sn alloy film 2 in which crystals are oriented in the thickness direction.

(Second embodiment)
FIG. 3 is a schematic cross-sectional view showing an enlarged portion of a portion provided with the solder film according to the second embodiment of the present invention.

As shown in FIG. 3, the solder film 21 further has an adhesion film 23. The adhesive film 23 is provided between the prism main body 11 and the Au—Sn alloy film 2. Therefore, in the solder film 21, the Au—Sn alloy film 2 is laminated on the adhesion film 23. By providing the adhesion film 23, the adhesion with the prism main body 11 can be improved.

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

As the material constituting the first layer 23a, for example, Ni, Cr, Ti, W, TiW, Mo, Ni—Cr alloy or the like can be used. Of these, Cr, Ti, or Ni is preferable. These materials may be used alone or in combination of two or more. It is desirable that the material constituting the first layer 23a contains 95% or more of the above-exemplified material. However, the first layer 23a may contain impurities and additives as long as the effects of the present invention are not impaired.

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.

As the material constituting the second layer 23b, for example, Ni, Pt, Pd, Ni—Cr alloy or the like can be used. Of these, Ni, Pt, Pd, or Ni—Cr alloy is preferable. These materials may be used alone or in combination of two or more. It is desirable that the material constituting the second layer 23b contains 95% or more of the above-exemplified material. However, the second layer 23b may contain impurities and additives as long as the effects of the present invention are not impaired.

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 adhesive film 23 may not be provided with the second layer 23b.

It is desirable that the third layer 23c has a function as a diffusion prevention layer. For example, it is desirable that the component of the Au—Sn alloy film 2 is a layer for preventing the components from diffusing into the first layer 23a and the second layer 23b. As a result, the bonding force of the solder film 21 to the package or the like can be further increased.

The third layer 23c is not particularly limited, but in the present embodiment, it is Pt. In this case, the components of the Au—Sn alloy film 2 can be further suppressed 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, or the like. These materials may be used alone or in combination of two or more. It is desirable that the third layer 23c contains 95% or more of the above-exemplified material. However, the third layer 23c may contain impurities and additives as long as the adhesion is not impaired.

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.

Further, the solder film 21 further has 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 on the outermost layer of the solder film 21.

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

As in the solder film 21 in the second embodiment, the adhesive film 23 may be further provided. Further, the Au film 24 may be provided on the outermost layer. When the outermost layer is the Au film 24, the outermost layer in contact with the package or the like can be made difficult to oxidize during mounting, and the bonding force due to the solder film 21 can be more reliably increased.

Further, also in the second embodiment, since the solder film 21 includes the Au—Sn alloy film 2, which is a single-layer film made of an alloy of Au and Sn, the surface is excellent in flatness, and it is a component for an optical device. When mounting a certain prism 20 on a package or the like, the bonding force can be increased.

In the first embodiment and the second embodiment, the prisms 10 and 20 have been described as components for optical devices. However, in the present invention, the component for an optical device may be an optical element, a submount for mounting the optical element, or a package member for mounting the optical element.

[Optical device]
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, the 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-like member having a bottom portion 35 and a side wall portion 36 arranged on the bottom portion 35. The package 34 can be made of, for example, a ceramic material. As the ceramic material, for example, alumina, aluminum nitride, or the like can be used. Of these, aluminum nitride is preferable from the viewpoint of further enhancing heat dissipation.

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

In this embodiment, the optical element 32 and the prism 10 are arranged on the metal film 38 on the mounting surface 35a. More specifically, the submount 33 is provided on the metal film 38, and the optical element 32 is arranged on the submount 33. At this time, the main surface 33a on one side of the submount 33 is joined to the optical element 32 by a solder film 1 (not shown). Further, the other side main surface 33b of the submount 33 is joined to the metal film 38 by a solder film 1 (not shown). Further, 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 the present embodiment. Such a configuration is particularly effective when the difference in thermal expansion rate 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 difficult to oxidize, the bonding force between the submount 33 or the prism 10 and the package 34 can be further increased in the manufacture of the optical device 31.

In this embodiment, the metal film 38 is provided on the entire surface of the mounting surface 35a on the bottom portion 35 and the entire surface of the inner surface 36a of the side wall portion 36. However, the metal film 38 may be provided at least in a portion where the submount 33 and the prism 10 are arranged.

A lid 37 is provided on the side wall portion 36 of the package 34 so as to seal the optical element 32 and the prism 10. The lid 37 is not particularly limited, but is a glass lid in the present embodiment. Further, the lid 37 and the side wall portion 36 are joined by a solder film 1 (not shown). In this case, since gas is not generated after the bonding, impurities are less likely to adhere to the reflective film 12 of the prism 10, and the reflection characteristics are less likely to be deteriorated.

In the present embodiment, the optical element 32 is a light source that emits light to the prism 10. The light source is not particularly limited, but for example, an LD, an LED, or the like can be used. As shown in FIG. 4, the light A emitted from the optical element 32 is reflected by the prism 10, passes through the lid 37, and is emitted to the outside of 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. Further, the sub mount 33 also serves as a heat sink. Therefore, the 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 prism 10 and the package 34 are joined by the solder film 1, the optical element 32 and the submount 33 are joined, the submount 33 and the package 34 are joined, and the lid 37 and the side wall portion 36 in the package 34 are joined. Are joined. Therefore, in the optical device 31, the bonding force between each component is enhanced. Therefore, the reliability of the optical device 31 is enhanced.

Further, in the optical device 31, the lid 37 and the side wall portion 36 in the package 34 may be joined by a solder film having a low melting point such as Sn—Ag. In this case, if the other members are joined by a solder film 1 having a melting point higher than that of the solder film, the optical element 32, the submount 33, and the prism 10 are mounted, and then the lid 37 and the side wall portion 36 are soldered. Due to heating when joining with a film, the optical element 32, the submount 33, and the prism 10 are unlikely to be displaced in the height direction. Therefore, the reliability of the optical device 31 can be further improved.

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

In the present invention, at least one of the bonding of the members constituting the optical element 32, the submount 33, the prism 10, and the package 34 may be bonded by the solder film 1, and is not particularly limited.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the following examples, and can be appropriately modified and implemented without changing the gist thereof.

(Example 1)
First, an alloy of Au and Sn is used 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 using a target made of an alloy of Au—Sn. An Au—Sn alloy film, which is a single-layer film composed of, was formed to obtain a solder film 41. At the time of sputtering, the mass ratio of Au and Sn at the target was set to 70:30. Argon (Ar) gas was used as the carrier gas, and the film formation temperature was set to about 100 ° C. by turning off the heater and kinetic energy of sputtering during film formation. The thickness of the obtained Au—Sn alloy film was 5 μm.

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

(Comparative Example 1)
A solder film 41 was obtained by alternately laminating a total of 180 layers of Au layers and Sn layers on a glass substrate 42 (manufactured by Nippon Electric Glass Co., Ltd., OA-10G, thickness: 0.197 mm) by thin film deposition. At this time, the thickness of each Au layer was set to 25.6 nm. The thickness of each Sn layer was set to 29.4 nm. The thickness of the entire solder film 41 was set to 5 μm.

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

(Evaluation of adhesion)
In the evaluation of the adhesion, an aluminum nitride substrate having an Au-plated portion was prepared as a package. Next, the substrate 40 with a film was attached to the Au-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 was evaluated by pushing the substrate 40 with a film from the side surface using a tensile compression tester (SV-201 manufactured by Imada Seisakusho Co., Ltd.). The adhesion was evaluated under the condition that the joining time was 10 seconds.

The results are shown in Table 1 below.

As is clear from Table 1, the solder film 41 of Example 1 using the Au—Sn alloy film, which is a single-layer film composed of an alloy of Au and Sn, has excellent surface flatness and a bonding force with a package. It was confirmed that it was excellent.

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 ... Adhesive film 23a ... First layer 23b ... Second layer 23c ... Third layer 24 ... Au film 31 ... Optical device 32 ... Optical element 33 ... Submount 33a ... One side Side main surface 33b ... Other side main surface 34 ... Package 35 ... Bottom 35a ... Mounting surface 36 ... Side wall 36a ... Inner surface 37 ... Lid 38 ... Metal film 40 ... Film-coated substrate 42 ... Glass substrate

Claims (14)

A solder film used to fix components in optical devices.
A solder film comprising an Au—Sn alloy film, which is a single-layer film composed of an alloy of Au and Sn. The solder film according to claim 1, wherein the Au—Sn alloy film does not have a concentration gradient of Au and Sn in the thickness direction. The solder film according to claim 1 or 2, wherein the Au—Sn alloy film is a sputter film formed by using a target made of an alloy of Au and Sn. The solder film according to any one of claims 1 to 3, wherein the crystals are oriented in the thickness direction in the Au—Sn alloy film. When the total mass of Au in the Au—Sn alloy film is MA and the total mass of Sn is MS, the ratio of the mass of Au to the total mass of Au and _Sn is _MA / ( _MA + _M ). The solder film according to any one of claims 1 to 4, wherein _S ) is 0.60 or more and 0.85 or less. The solder film according to any one of claims 1 to 5, further comprising an adhesive film provided between the component and the Au—Sn alloy film. The adhesive film
A first layer provided on the component side and comprising at least one selected from the group consisting of Cr, Ti, and Ni.
A second layer, which is provided on the first layer and contains at least one selected from the group consisting of Ni, Pt, Pd, and Ni—Cr alloys.
A third layer, which is provided on the second layer and contains Pt or Au,
The solder film according to claim 6. The method according to any one of claims 1 to 7, further comprising an Au film provided on a main surface of the Au—Sn alloy film opposite to the component side, wherein the Au film is the outermost layer. The solder film described. The solder film according to any one of claims 1 to 8, wherein the arithmetic average roughness Ra of the surface is 0.05 μm or less. The solder film according to any one of claims 1 to 9, wherein the maximum height Rz of the surface is 0.25 μm or less. The solder film according to any one of claims 1 to 10, wherein the thickness of the entire solder film is 1 μm or more and 15 μm or less. The main body of the part with the main surface and
The solder film according to any one of claims 1 to 11, which is provided on the main surface of the component body, and the solder film.
Parts for optical devices. The optical device according to claim 12, 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 package member for mounting the optical element. parts. With the prism
An optical element that emits light to the prism or receives light from the prism,
The package on which the prism and the optical element are mounted,
A submount provided between the optical element and the package,
Equipped with
The prism and the package are bonded, the optical element and the submount are bonded, the submount and the package are bonded, or the package is bonded by the solder film according to any one of claims 1 to 11. An optical device in which the members constituting the device are joined together.

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