JP7173347B2 - Lid material for light-emitting device, method for manufacturing lid material, and light-emitting device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lid material used in a light emitting device having an LED (Light Emitting Diode), a method for manufacturing the lid material, and a light emitting device.

A light-emitting device using an LED generally has a structure in which the LED is sealed inside a package to improve reliability. As a specific structural example, there is a structure in which the LED is housed in a cavity of a package base (for example, a ceramic package) and the cavity opening of the package base is sealed with a lid.

In such a structure, the lid must be transparent to the LED illumination. In the case where the LED is a deep-ultraviolet LED that emits deep ultraviolet rays, it has been conventionally considered suitable to use quartz glass for the lid (for example, Patent Document 1).

Japanese Patent No. 6294417

However, when quartz glass is used for the lid, the number of man-hours may increase in the element manufacturing process of the light-emitting device. In such a case, using crystal for the lid has the advantage of reducing man-hours.

An Au—Sn alloy is used as a brazing material to seal the ceramic package with a crystal lid. Since crystal has low adhesion to Au--Sn alloy, a base film is required to improve adhesion. Such a base film is also necessary when quartz glass is used for the lid. Therefore, when a ceramic package is sealed with a lid, it is common to use a lid material (lid and base film) in which a base film is formed in advance on the joint surface of the lid with the package. Moreover, in such a lid material, a brazing material is previously fused to the base film.

However, the inventors of the present invention have discovered that the lid material using the crystal lid causes problems such as peeling of the lid and poor airtightness depending on the conditions for forming the underlying film. In other words, if the underlying film is formed under the same conditions as in the case of using quartz glass for the lid, the adhesion is extremely low, requiring a drastic change in conditions.

It goes without saying that even when quartz glass is used for the lid, the reliability of the light-emitting device can be improved if the adhesion to the Au--Sn alloy can be further enhanced. In the conventional technology using quartz glass for the lid, it was common to use a Cr (chromium) film as an underlying film for obtaining adhesion to the Au—Sn alloy. Sn alloy diffusion is likely to occur, and there is ample room for improvement from the viewpoint of film peeling and adhesion.

The present invention has been made in view of the above problems, and in a light emitting device in which an LED is arranged inside a package and sealed with a lid material, a lid material having a suitable base film that does not cause lid peeling or airtightness failure , an object of the present invention is to provide a method for manufacturing a lid material and a light emitting device.

In order to solve the above problems, the lid material of the first aspect of the present invention is a lid material used in a light-emitting device in which an LED is sealed in a package, and a first metallized film formed on a sealing surface of the lid body, the first metallized film being a first layer directly formed on the lid body; and a second layer formed on the first layer, wherein the first layer is a layer containing a Ti film having a thickness of 20 to 700 nm, and the second layer is Ni, Ti, Au. and an alloy film containing Sn.

According to the above configuration, in a light-emitting device in which an LED is arranged inside a package and sealed with a lid material, it is possible to obtain a lid material having a suitable base film that does not cause peeling of the lid or poor airtightness.

Further, in the above lid material, the Ti film included in the first layer may be a Ti film having a film thickness of 200 to 300 nm.

Further, in the lid material, the first layer may have an oxide film made of titanium oxide on its surface.

Further, in the lid material, the first layer has a buffer film made of an Au film and another Ti film laminated in order from the side close to the Ti film on the Ti film. be able to.

In the above lid material, the second layer has Ni alloy films on the inner peripheral edge side and the outer peripheral edge side thereof, and the alloy films containing Ni, Ti, Au and Sn are interposed between the Ni alloy films. It can be set as the structure formed.

Further, the lid material may be configured such that the lid body is crystal.

Further, in order to solve the above problems, a method for manufacturing a lid material according to a second aspect of the present invention is a method for manufacturing a lid material used for a light-emitting device in which an LED is sealed in a package. forming a base film on the sealing surface of the lid body having transparency to the irradiation light of the LED, forming a first layer containing a Ti film having a thickness of 20 to 700 nm on the sealing surface of the lid body; a second step of forming an oxide film made of titanium oxide on the surface by oxidizing the Ti film on the uppermost layer of the first layer formed in the first step; a third step of forming, on the first layer after the step, a second layer containing a Ni alloy film and an Au film laminated in order from the side closer to the first layer; and and a fourth step of fusing a brazing material formed as an Au—Sn preform onto the Au film.

Further, in the method for manufacturing a lid material, the Ti film formed in the first step may have a film thickness of 200 to 300 nm.

Further, in the method for manufacturing the lid material, in the first step, on the Ti film, a buffer film composed of an Au film and another Ti film, which are laminated in order from the side closer to the Ti film, is formed. can do.

Further, in the method for manufacturing a lid material, the base film has a downward structure in an upper layer portion including the arbitrary film in any film except for the lowermost film, and in the downward structure, the downward A configuration in which the inner peripheral edges of the membranes included in the structure are pulled down further than the inner peripheral edges of the other membranes, and the outer peripheral edges of the membranes included in the pulled-down structure are pulled down further inward than the outer peripheral edges of the other membranes. can be

Further, the method for manufacturing the lid material may be configured such that the lid body is made of crystal.

In order to solve the above problems, a light-emitting device according to a third aspect of the present invention is a light-emitting device in which an LED is sealed in a package, wherein the LED and the LED are placed in a cavity. It has a package base for housing and a lid material for sealing the cavity opening of the package base, wherein the lid material is the lid material described above.

Further, in the above light emitting device, the package base may be made of aluminum nitride.

Further, in the above light emitting device, the LED may be a deep ultraviolet LED.

INDUSTRIAL APPLICABILITY The present invention has the effect of obtaining a lid material having a suitable base film that does not cause peeling of the lid or poor airtightness in a light emitting device in which an LED is arranged inside a package and sealed with a lid material.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows an example of the basic structure of the light-emitting device to which this invention is applied. 1. It is sectional drawing which shows roughly the manufacturing method of the light-emitting device of FIG. It is a bottom view of a lid member. 4 is a partial cross-sectional view showing the structure of an underlying film formed in the lid material film-forming step of Embodiment 1. FIG. FIG. 4 is a cross-sectional view showing a fusion bonding step of the lid material of Embodiment 1; FIG. 10 is an SEM photograph of a cross section of a part of the bonding layer in the light emitting device after sealing. FIG. 10 is a cross-sectional view showing a fusion bonding step of a lid material according to Embodiment 2; FIG. 10 is a partial cross-sectional view showing the structure of an underlying film formed in a lid material film-forming step of Embodiment 2; FIG. 11 is a cross-sectional view showing a fusion bonding step of a lid material according to Embodiment 3; FIG. 11 is a partial cross-sectional view showing the configuration of an underlying film formed in a lid material film-forming step of Embodiment 3; FIG. 11 is a partial cross-sectional view showing the structure of a first metallized film of a lid material according to Embodiment 3; FIG. 10 is a partial cross-sectional view showing another configuration of the base film in the lid material of Embodiment 3; FIG. 4 is a cross-sectional view showing another example of the basic structure of the light emitting device to which the invention is applied; FIG. 4 is a cross-sectional view showing still another example of the basic structure of the light emitting device to which the invention is applied;

[Embodiment 1]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Basic structure of light-emitting device]
First, the basic structure of a light emitting device 10 to which the present invention is applied will be described with reference to FIG. As shown in FIG. 1, the light emitting device 10 is generally composed of a ceramic package 11, a crystal lid (lid body) 12 and an LED chip 13. As shown in FIG. That is, the light emitting device 10 has a structure in which the LED chip 13 is housed in the cavity 111 of the ceramic package 11 and the opening of the cavity 111 is sealed with the crystal lid 12 .

The ceramic package 11 is a substantially rectangular parallelepiped package base, and has an opening of a cavity 111 on its upper surface, and a sealing surface 11A with the crystal lid 12 is formed around this opening. Mounting pads 112 for mounting the LED chip 13 are formed on the bottom surface of the cavity 111 , and external connection terminals 113 are formed on the bottom surface of the ceramic package 11 . The mounting pads 112 and the external connection terminals 113 are electrically connected via through holes (not shown). It should be noted that the ceramic package 11 is preferably made of a material with high thermal conductivity so that heat generated from the LED chip 13 can escape, and aluminum nitride can be preferably used. Here, the case where the package base of the light emitting device 10 is a ceramic base is exemplified, but the package base may be a crystal base.

The crystal lid 12 is a rectangular crystal plate having substantially the same size as the ceramic package 11 in plan view. The crystal lid 12 is bonded to the sealing surface 11A of the ceramic package 11 with the bonding layer 14 interposed therebetween.

In the light emitting device 10 shown in FIG. 1, the LED chip 13 is mounted on the ceramic package 11 by FCB (Flip Chip Bonding). However, the present invention is not limited to this, and the LED chip 13 may be mounted on the ceramic package 11 by wire bonding.

The LED chip 13 is preferably a deep UV LED that emits deep UV. Deep ultraviolet rays refer to ultraviolet rays with relatively short wavelengths, and are mainly used for sterilization and disinfection. Since the crystal lid 12 is transparent to deep ultraviolet rays, it can be used when the LED chip 13 is a deep ultraviolet LED. However, the LED chip 13 is not limited to a deep-ultraviolet LED as long as it emits light in the transmission wavelength range of crystal.

As a material having transparency to deep ultraviolet rays, there is quartz glass that has been conventionally used. However, if quartz glass is used as the lid of the light emitting device 10, the number of test steps in the airtightness test may increase. . The use of the crystal lid 12 in the light-emitting device 10 has the advantage that the number of test steps is reduced when conducting the airtightness test, and the airtightness test can be performed more easily.

[Method for manufacturing light-emitting device]
Next, a method for manufacturing the light emitting device 10 shown in FIG. 1 will be described. 2A to 2C are cross-sectional views schematically showing a method for manufacturing the light emitting device 10. FIG.

As shown in FIG. 2, the light emitting device 10 is manufactured by bonding a lid material 20 and a package material 30 with a bonding material 40 interposed therebetween. Here, the lid material 20 is obtained by forming a first metallized film 41 on the lower surface (joint surface) of the crystal lid 12 . As shown in FIG. 3, the first metallized film 41 is formed in an annular shape on the lower surface of the crystal lid 12 along the contour of the crystal lid 12 . The first metallized film 41 is formed by fusing a brazing material 41B (see FIG. 5) to a base film 41A (see FIGS. 4 and 5) for enhancing adhesion between the crystal lid 12 and the bonding layer 14. is. A specific configuration of the first metallized film 41 will be described later.

The package material 30 is obtained by forming a second metallized film 42 on the sealing surface 11A of the ceramic package 11 on which the LED chip 13 is mounted. The second metallized film 42 is annularly formed along the shape of the sealing surface 11A so as to overlap the first metallized film 41 when the lid material 20 and the package material 30 are opposed to each other. The second metallized film 42 is a base film for enhancing adhesion between the ceramic package 11 and the bonding layer 14 . As the second metallized film 42, when the package base is a ceramic base, a Ni alloy/Au film (or Ni/Au film) or the like formed on top of a metallized material such as tungsten or molybdenum is preferably used. Also, the film thickness of the second metallized film 42 is preferably in the range of 150 to 700 nm. Furthermore, when the package base is a crystal base, the second metallized film 42 may be a Ti alloy/Au film (or a Ti/Au film).

As shown in FIG. 2, the light-emitting device 10 is manufactured by stacking the lid material 20 and the package material 30 and heating the lid material 20 and the package material 30 while applying a load to join them. I do. That is, the first metallized film 4 and the second metallized film 42 are melted by heating, and then cooled while applying a load. The melted first metallized film 41 and second metallized film 42 are solidified by cooling to form the bonding layer 14 shown in FIG.

[Structure and Manufacturing Method of Lid Material]
Next, the configuration and manufacturing method of the lid member 20 will be described.

As described above, the lid member 20 is formed by forming the first metallized film 41 on the lower surface of the crystal lid 12, and the first metallized film 41 is formed by fusing the brazing material 41B to the base film 41A. there is The first metallized film 41 is formed through a process of forming a base film 41A and a process of fusing a brazing material 41B. First, the configuration of the base film 41A formed by the film forming process will be described with reference to FIG.

As shown in FIG. 4 , the underlying film 41 A of the first metallized film 41 is composed of a first metal layer 411 and a second metal layer 412 .

A first metal layer 411 directly formed on the crystal lid 12 has a single-layer structure made of a Ti (titanium) film. The second metal layer 412 is formed on the first metal layer 411, and is a laminate including a Ni—Ti (nickel-titanium) film 4121 and an Au (gold) film 4122 in order from the side closer to the first metal layer 411. have a structure. Incidentally, the Ni--Ti film 4121 in the second metal layer 412 preferably has a film thickness in the range of 50 to 1000 nm. Also, the Ni--Ti film 4121 can be replaced with another Ni alloy film.

As a method of manufacturing the base film 41A in the lid material 20, first, a Ti film that becomes the first metal layer 411 is formed on one surface of the crystal lid 12 (the surface facing the package material 30) by physical vapor deposition. After the Ti film is formed, it is once removed from the film forming apparatus, and the surface of the Ti film is exposed to the air. As a result, an oxide film made of titanium oxide is formed on the surface of the Ti film. Thereafter, a Ni—Ti film 4121 is formed on the Ti film, which is the first metal layer 411, by physical vapor deposition, and an Au film 4122 is formed on the Ni—Ti film 4121 by physical vapor deposition. . That is, the second metal layer 412 has a layered structure of the Ni—Ti film 4121 and the Au film 4122 .

The method of oxidizing the Ti film to form an oxide film on its surface is not limited to the method of exposing the surface of the Ti film to air. For example, a method of forming a Ti oxide film by introducing oxygen when forming a Ti film by sputtering, or a method of promoting oxidation of the surface of the formed Ti film by oxygen plasma are also possible.

After the base film 41A is formed, the brazing material 41B is fused onto the base film 41A by a fusion process. In this fusing process, as shown in FIG. 5, the brazing material 41B is placed on the base film 41A and subjected to heat treatment (baking in a heating furnace). By this heat treatment, the base film 41A and the brazing material 41B are integrated to form the first metallized film 41. Next, as shown in FIG. The brazing material 41B before fusion bonding is formed by preforming gold-tin (Au--Sn) used as a brazing material into an annular shape substantially the same as that of the base film 41A. The thickness of the preformed brazing material 41B is preferably in the range of 10 to 20 μm.

In the first metallized film 41 after the fusion bonding step, the laminated structure of the second metal layer 412 (the laminated structure of the Ni—Ti film 4121 and the Au film 4122) in the base film 41A before heating is lost. Specifically, by heating in the fusion bonding step, the second metal layer 412 and the brazing filler metal 41B melt and alloy (form eutectic bonding) to form the alloy layer 43 (see FIG. 6). On the other hand, the first metal layer 411 is maintained in a layered state even after the fusion process, and does not form a eutectic bond.

FIG. 6 is an SEM photograph of a cross section of a part of the bonding layer 14 in the light emitting device 10 after sealing. As shown in FIG. 6, the bonding layer 14 has a first metal layer 411, an alloy layer 43, a Ni—Sn alloy layer 422, and a Ni plating layer 421 in order from the crystal lid 12 side. Since the oxide film on the surface of the first metal layer 411, which is a Ti film, is extremely thin, it cannot be visually recognized as a distinct layer in the SEM photograph of FIG. However, the reason why the first metal layer 411, which is a Ti film, is maintained in a layered state without forming a eutectic bond is that the oxide film on the surface of the Ti film exists as a barrier film.

The alloy layer 43 is a layer in which the second metal layer 412 and the brazing filler metal 41B in the base film 41A before heating are melted to form a eutectic bond. The alloy layer 43 includes the second metal layer 412 and the brazing material 41B in addition to the “Au—Snζ′ phase” and “Au—Snδ phase” in gold tin (Au—Sn), which is the brazing material 41B. It includes "Ni-Sn alloy" and "Ti-Sn alloy" which can be mixed together. That is, the alloy layer 43 becomes an alloy layer containing Ni, Ti, Au and Sn.

The Ni plated layer 421 is a layer included in the second metallized film 42 of the package material 30 . Also, the Ni—Sn alloy layer 422 is a layer formed by alloying the joint portion between the first metallized film 41 and the second metallized film 42 . That is, the Ni—Sn alloy layer 422 is an alloy layer containing Ni, Ti, Au and Sn, like the alloy layer 43 . More specifically, in the Ni--Sn alloy layer 422 formed by welding the lid material 20 to the package material 30, the Ni plating layer on the package material 30 side and the Sn of the Au--Sn alloy on the lid material 20 side combine to form Ni - forming a Sn layer; Therefore, the Au—Sn alloy becomes non-eutectic. Such a non-eutectic state of the Au—Sn alloy is preferable after the lid material 20 and the package material 30 are welded together.

Incidentally, when the package material 30 of the light emitting device 10 is a crystal base and the first metallized film 41 is a Ti/Au film, a Ti—Sn layer is formed instead of the Ni—Sn alloy layer 422 . That is, the Ti plating layer on the package material 30 side and the Sn of the Au--Sn alloy on the lid material 20 side combine to form a Ti--Sn layer.

The SEM photograph of FIG. 6 is a photograph of a cross section of the bonding layer 14 in the light emitting device 10 after sealing. 1 layer) 411 and an alloy layer (second layer) 43 already included.

[Conditions for forming the first metallized film]
In the lid material 20 described above, it was confirmed that the film thickness of the first metallized film 41 needs to be controlled in order to obtain suitable adhesion of the crystal lid 12 in the light emitting device 10 . In particular, it is necessary to control the film thickness of the Ti film, which is the first metal layer 411, within an appropriate range. A discussion based on experiments will be made below.

Here, the film thickness of the first metal layer 411 was changed as a parameter, the light-emitting device 10 was manufactured by the manufacturing method described above, and the appearance evaluation and the airtightness evaluation by the airtightness test (helium leak test) were performed. In the appearance evaluation, the discoloration of the metallized film viewed from the crystal lid 12 side and the presence or absence of cracks in the crystal lid 12 were visually confirmed. In each manufactured light emitting device 10, the thicknesses of the Ni--Ti film 4121 and the Au film 4122 of the second metal layer 412 were fixed at 300 nm and 50 nm, respectively. The thickness of the Au--Sn preform, which is the brazing material 41B, was fixed at 15 μm, the second metallized film 42 was a Ni alloy/Au film, and the total film thickness was fixed at 5 μm. Experimental results are shown in Table 1 below.

Regarding discoloration, discoloration occurs in a relatively wide range under conditions 1 and 2 (thicknesses of 7 nm and 10 nm), and the evaluation is "x". In addition, under conditions 3 to 6 and 10 to 15 (film thickness 20 nm, 50 nm, 100 nm, 150 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, and 900 nm), slight discoloration occurred, and the evaluation was "○". ing. Under conditions 7 to 9 (film thicknesses of 200 nm, 250 nm, and 300 nm), almost no discoloration occurred, and the evaluation was "⊚".

This discoloration indicates that separation has occurred between the crystal lid 12 and the metallized film that is the bonding layer 14 . That is, when the film thickness of the first metal layer 411 is not sufficient, Au and Sn from the bonding material 40 diffuse to the contact surface with the crystal lid 12 in the Ti film, which is the first metal layer 411, and the first metal layer 411 It is considered that the detachment (that is, discoloration) occurred due to a decrease in adhesion between the crystal lid 12 and the crystal lid 12 . This is clear from the wide range of discoloration occurring under conditions 1 and 2 where the film thickness of the first metal layer 411 is thin. In fact, under condition 1 in which the film thickness of the first metal layer 411 is the thinnest, the airtightness evaluation is "x" (poor airtightness occurs). In condition 2, no airtightness failure was detected at the stage of airtightness evaluation, and the evaluation was "O". For this reason, conditions 1 and 2 are comprehensively evaluated as "x".

As the film thickness of the first metal layer 411 increases, the diffusion of Au and Sn is suppressed in the Ti film that is the first metal layer 411, and the adhesion between the crystal lid 12 and the metallized film that is the bonding layer 14 is improved. . Under conditions 3 to 6, discoloration was evaluated as "◯", and under conditions 7 to 9, discoloration was evaluated as "⊚". Since conditions 3 to 9 are also evaluated as "good" in airtightness evaluation, the overall evaluation is "good" for conditions 3 to 6 and "excellent" for conditions 7 to 9.

In conditions 10-15, the film thickness of the first metal layer 411 is even thicker, but the evaluation for discoloration is "good", which is lower than the evaluation in conditions 7-9. However, this does not mean that the adhesion of the crystal lid 12 under conditions 10-15 is lower than the adhesion of the crystal lid 12 under conditions 7-9. The reason why the evaluation of discoloration is "good" in conditions 10 to 15 is considered as follows.

In the light-emitting device 10, the ceramic package 11 and the crystal lid 12 are made of different materials and therefore have different coefficients of thermal expansion. In conditions 10 to 15, since the thickness of the first metal layer 411 is large and the adhesion is high, warping occurs due to the difference in thermal expansion between the ceramic package 11 and the crystal lid 12, and this warping causes separation. Conceivable. That is, since conditions 7 to 9 have lower adhesion than conditions 10 to 15, even if a difference in thermal expansion occurs between the ceramic package 11 and the crystal lid 12, the first metal layer 411 and the crystal lid 12 are It is considered that the difference in thermal expansion can be absorbed by the gap between the layers, and the effect of suppressing the peeling due to the warp is considered to have worked. In fact, under conditions 14 and 15, cracks also occurred in the crystal lid 12, and it is believed that the crystal cracks were caused by warping due to the difference in thermal expansion.

When the material of the ceramic package 11 is aluminum nitride, the difference in thermal expansion coefficient between crystal and aluminum nitride is greater than the difference in thermal expansion coefficient between silica glass and aluminum nitride. Therefore, when the crystal lid 12 is used, it is more likely to warp due to the difference in thermal expansion compared to the conventional structure using a quartz glass lid, and it is necessary to consider such warping.

Regarding the airtightness evaluation of conditions 10 to 15, conditions 10 to 13 are evaluated as ◯, and conditions 14 and 15 are evaluated as x. Therefore, conditions 10 to 13 are comprehensively evaluated as "good", and conditions 14 and 15 are comprehensively evaluated as "poor".

As described above, in the lid member 20 according to the present embodiment, if the film thickness of the first metal layer 411 is too thin or too thick, the light-emitting device 10 cannot be reliably airtight. As is clear from the results in Table 1 above, the film thickness of the first metal layer 411 is preferably in the range of 20-700 nm, more preferably in the range of 200-300 nm.

[Embodiment 2]
[Structure and Manufacturing Method of Lid Material]
In Embodiment 1, the lid material 20 has the first metallized film 41 as a base film. It has been explained that it is a suitable base film that does not cause airtightness failure. However, since the first metallized film 41 in Embodiment 1 has a high degree of adhesion, the light emitting device 10 may have a problem of lid cracking. In particular, when the sealing load is large (for example, 100 gf or more) or in thermal shock tests, the lid tends to crack easily. In the second embodiment, a lid material that can prevent cracking of the lid even when the sealing load is large or in a thermal shock test will be described.

As shown in FIG. 5, the first metallized film 41 in the lid material 20 is formed by fusing a brazing material 41B to a base film 41A. In contrast, as shown in FIG. 7, the lid member 21 according to the second embodiment has a first metallized film 51 in place of the first metallized film 41 of the lid member 20. The metallized film 51 is formed by fusing the brazing material 41B to the base film 51A.

FIG. 8 is a partial cross-sectional view showing the configuration of the base film 51A in the lid material 21 according to the second embodiment. Here, the base film 51A includes a first metal layer (first layer) 511 and a second metal layer (second layer) 412, as shown in FIG. That is, the base film 51A of the lid member 21 has a configuration in which the first metal layer 411 is changed to the first metal layer 511 in the base film 41A of the lid member 20 according to the first embodiment.

The first metal layer 411 of Embodiment 1 has a single-layer structure consisting of only a Ti film, but the first metal layer 511 has a laminated structure consisting of a Ti film 5111, an Au film 5112 and a Ti film 5113. is doing. Here, the Ti film 5111 corresponds to the Ti film forming the first metal layer 411 of the first embodiment. That is, similarly to the Ti film of the first metal layer 411, the Ti film 5111 preferably has a thickness of 20 to 700 nm, more preferably 200 to 300 nm.

The Au film 5112 and the Ti film 5113 in the first metal layer 511 are formed as buffer films for preventing cracking of the lid when the sealing load is large or during thermal shock tests. As described in the first embodiment, the ceramic package 11 and the crystal lid 12 in the light emitting device 10 are made of different materials, and therefore have different coefficients of thermal expansion. Therefore, warping occurs due to the difference in thermal expansion between the ceramic package 11 and the crystal lid 12, and this warping may cause cracks in the crystal. On the other hand, in the light emitting device 10 using the lid material 21, the difference in thermal expansion between the ceramic package 11 and the crystal lid 12 can be absorbed by deformation of the buffer films (that is, the Au film 5112 and the Ti film 5113). As a result, it is thought that warpage can be reduced and crystal cracking can be suppressed.

As a method of manufacturing the lid material 21, a Ti film 5111, an Au film 5112, and a Ti film 5113, which become the first metal layer 511, are sequentially formed on one surface (the surface facing the package material 30) of the crystal lid 12 by physical vapor deposition. Form. After the first metal layer 511 is formed, it is once removed from the film forming apparatus, and the surface of the uppermost Ti film 5113 is exposed to the air. As a result, an oxide film made of titanium oxide is formed on the surface of the Ti film 5113 .

In the first embodiment, an oxide film made of titanium oxide is formed on the surface of the first metal layer 411, and in the second embodiment, the Ti film 5111 is the Ti film of the first metal layer 411 in the first embodiment. is considered to be equivalent to However, since the oxide film made of titanium oxide forms a boundary between the first metal layer and the second metal layer, in the lid material 21 according to the second embodiment, the oxide film made of titanium oxide is Ti It is formed not on the film 5111 but on the surface of the Ti film 5113 on top of the first metal layer 511 . In addition, the method of forming an oxide film on the surface of the Ti film 5113 may be a method of forming an oxide Ti film by introducing oxygen when forming a Ti film by sputtering, as in the first embodiment, or a method of forming a Ti oxide film. It is also possible to promote the oxidation of the surface of the Ti film formed by oxygen plasma. After forming the first metal layer 511, the method for forming the second metal layer 412 is the same as the method described in the first embodiment. By forming the first metal layer 511 and the second metal layer 412 , an underlying film 51 A is formed on the crystal lid 12 .

After the base film 51A is formed, the brazing material 41B is fused onto the base film 51A by a fusion process. In this fusing step, as shown in FIG. 7, the brazing material 41B is placed on the base film 51A and heat treated (baked in a heating furnace). By this heat treatment, the base film 51A and the brazing material 41B are integrated to form the first metallized film 51. Next, as shown in FIG.

[Conditions for forming the first metallized film]
In the lid material 21 described above, it has been confirmed that controlling the film thickness of the base film is effective in obtaining suitable adhesion of the crystal lid 12 in the light emitting device 10 and the effect of preventing cracks in the crystal. In particular, it is effective to control the film thickness of the Au film 5112 in the first metal layer 511 within an appropriate range. A discussion based on experiments will be made below.

Here, the film thicknesses of the Ti film 5111, the Au film 5112, and the Ti film 5113 in the first metal layer 511 are changed as parameters, the light emitting device 10 is manufactured by the manufacturing method described above, and the appearance evaluation and airtightness test ( A helium leak test) was performed to evaluate airtightness. In the appearance evaluation, the discoloration of the metallized film viewed from the crystal lid 12 side and the presence or absence of cracks in the crystal lid 12 were visually confirmed. In each manufactured light emitting device 10, the thicknesses of the Ni--Ti film 4121 and the Au film 4122 of the second metal layer 412 were fixed at 300 nm and 50 nm, respectively. The thickness of the Au--Sn preform, which is the bonding material 40, was fixed at 15 .mu.m, the second metallized film 42 was a Ni alloy/Au film, and the total film thickness was fixed at 5 .mu.m. Experimental results are shown in Table 2 below. In the film thickness of the first metal layer in Table 2, the Ti film thickness in the left column indicates the film thickness of the Ti film 5111 , and the Ti film thickness in the right column indicates the film thickness of the Ti film 5113 .

Conditions 16 to 18 in Table 2 do not have the Au film 5112 and the Ti film 5113 as buffer films, but the larger the film thickness of the Ti film 5111, the better the results. In addition, when the film thickness of the Ti film 5111 is 250 nm (Condition 3), which is considered to be the preferred range in the first embodiment, the comprehensive evaluation is also "Good".

On the other hand, in the conditions 18 to 25 having the Au film 5112 and the Ti film 5113 as the buffer films, the overall evaluation is "○" or better, and especially in the conditions 21 to 24, the overall evaluation is "◎". It's becoming Under Conditions 21 to 24, the discoloration evaluation is "⊚", which indicates that the adhesion of the crystal lid 12 in the light emitting device 10 is further improved. This is because, in the light emitting device 10, the difference in thermal expansion between the ceramic package 11 and the crystal lid 12 is absorbed by the buffer film (that is, the Au film 5112 and the Ti film 5113), thereby reducing the warpage. is also considered to have been reduced. This effect is improved by appropriately controlling the thickness of the Au film 5112. The thickness of the Au film 5112 is preferably in the range of 100 to 700 nm, more preferably in the range of 300 to 600 nm. preferable.

Conditions 26 and 27 in Table 2 have a buffer film, but the airtightness evaluation is "x" (the comprehensive evaluation is also "x"). In addition, under condition 27, the evaluation is "x" even for crystal cracking. These results are considered to be due to the fact that the total film thickness of the underlying film was increased as a result of making the buffer film too thick, and problems were caused by the influence of stress. That is, when the total thickness of the underlying film is increased, the thickness of the entire underlying film becomes non-uniform, and the stress applied to the crystal lid 12 increases due to the non-uniform film thickness, which causes crystal cracks. be done. This suggests that there is an upper limit to the thickness of the buffer film.

[Embodiment 3]
[Structure of lid material]
In Embodiments 1 and 2, the Ni--Ti film 4121 and the Au film 4122 included in the second metal layer 412 are formed so that the formation widths (metallization widths) of these films are the same (the Ni--Ti film 4121 is formed so that the Au film 4122 is completely superimposed thereon. However, in this case, depending on the manufacturing conditions of the light-emitting device 10, problems such as peeling of the lid and poor airtightness may occur in the evaluation stage. In the third embodiment, a lid material that can more reliably prevent lid peeling and airtightness failure will be described.

As shown in FIG. 9, the lid member 22 according to the third embodiment has a first metallized film 61 in place of the first metallized film 51 of the lid member 21. The first metallized film 61 is It is formed by fusing the brazing material 41B to the base film 61A.

FIG. 10 is a partial cross-sectional view showing the configuration of the base film 61A in the lid member 22 according to the third embodiment. The base film 61A includes a first metal layer (first layer) 511 and a second metal layer (second layer) 612, as shown in FIG. However, the lid member 22 according to the third embodiment is characterized by the structure of the second metal layer. For this reason, in the lid member 22 of FIG. good too.

The second metal layer 612 has a laminated structure including a Ni—Ti film 6121 formed on the first metal layer 511 and an Au film 6122 formed on the Ni—Ti film 6121 . The Ni--Ti film 6121 can be the same film as the Ni--Ti film 4121 in the lid members 20 and 20A. The Au film 6122 differs from the Au film 4122 in the lid members 20 and 21 only in film formation width.

That is, in the base film 61A, the Au film 6122 is formed with a width narrower than that of the Ni--Ti film 6121. As shown in FIG. More specifically, in the Au film 6122, the inner peripheral edge of the Au film 6122 is pulled down further than the inner peripheral edge of the Ni—Ti film 6121, and the outer peripheral edge of the Au film 6122 is lower than the outer peripheral edge of the Ni—Ti film 6121. It has an inwardly pulled down structure (a structure having a gap between the peripheral edge of the Au film 6122 and the peripheral edge of the Ni—Ti film 6121). The terms "inner side" and "outer side" here mean "inner side" and "outer side" when viewed from the center of the lid member 22, respectively. Further, the pulling width of the Au film 6122 on the inner side and the outer side of the base film 61A need not be the same, and as shown in FIG. .

As described in the first embodiment, when the brazing material 41B is fused to the base film 61A and when the lid material 22 and the package material 30 are joined to manufacture the light-emitting device 10, the base film 61A is originally Only the second metal layer 412 melts to form a eutectic bond with the braze material 41B. However, depending on manufacturing conditions (for example, if the sealing load during bonding is large), the alloy formed by eutectic bonding (an alloy containing Ni, Ti, Au, and Sn) may wrap around the bonding layer 14 from the side surface. There is a risk of reaching the first metal layer 411 . In this case, the Au and Sn components of the alloy that reach the first metal layer 411 infiltrate into the first metal layer 411 and reduce the adhesion between the first metal layer 411 and the crystal lid 12, resulting in lid peeling and poor airtightness. considered to be a factor. A similar problem occurs when the lid material 21 and the package material 30 are joined to manufacture the light emitting device 10 .

On the other hand, when the lid material 22 and the package material 30 are bonded to manufacture the light-emitting device 10, the eutectic bonding is formed only in the region substantially overlapping the formation region of the Au film 6122. FIG. This is because Au is essential for the formation of the eutectic junction. In the lid material 22, the Au film 6122 has a pull-down structure with respect to the Ni—Ti film 6121, so the alloy formed by the eutectic bonding wraps around from the side surface of the bonding layer 14 and the first metal layer 511 ( or 411), and as a result, it is possible to prevent lid peeling and poor airtightness.

More specifically, the eutectic bonding when the brazing material 41B is fused to the base film 61A is formed substantially corresponding to the region where the Au film 6122 is formed, and is formed in the peripheral region where the Au film 6122 is pulled down. not. That is, as shown in FIG. 11, the alloy layer 43 formed by melting the second metal layer 412 and the brazing material 41B has a Ni alloy film (without eutectic bonding) on the inner and outer peripheral edge portions thereof. Ni--Ti films 6121) remain on the substrate, and alloy films containing Ni, Ti, Au and Sn (alloy films by eutectic bonding) are formed between these Ni alloy films. In this way, since the Ni alloy film remaining without eutectic bonding exists in the peripheral portion of the alloy layer 43 , the alloy formed by the eutectic bonding wraps around from the side surface of the bonding layer 14 to form the first metal. It can prevent reaching layer 511 (or 411).

[Conditions for forming the first metallized film]
In the lid material 22 described above, it was confirmed that controlling the formation width of the Au film 6122 in the second metal layer 612 is effective in obtaining suitable adhesion of the crystal lid 12 in the light emitting device 10 . A discussion based on experiments will be made below.

Here, the film thicknesses of the Ti film 5111, Au film 5112 and Ti film 5113 in the first metal layer 511 were fixed to 250 nm, 500 nm and 50 nm, respectively. Also, the film thicknesses of the Ni—Ti film 6121 and Au film 6122 in the second metal layer 612 were fixed at 300 nm and 50 nm, respectively. Then, the light emitting device 10 was manufactured by the manufacturing method described above while changing the pull down width of the Au film 6122 as a parameter, and the appearance evaluation and the airtightness evaluation by the airtightness test (helium leak test) were performed. In the appearance evaluation, the discoloration of the metallized film viewed from the crystal lid 12 side and the presence or absence of cracks in the crystal lid 12 were visually confirmed. The thickness of the Au--Sn preform, which is the bonding material 40, was fixed at 15 .mu.m, the second metallized film 42 was a Ni alloy/Au film, and the total film thickness was fixed at 5 .mu.m. Experimental results are shown in Table 3 below.

From the comparison of conditions 28 to 30 in Table 3, discoloration occurs in condition 28, which does not have a pull-down structure, and the airtightness evaluation is "x" (overall evaluation is also "x"), whereas the pull-down structure is used. Under the conditions 29 and 30, the airtightness evaluation is "◯" (the comprehensive evaluation is also "◯"). From this, it can be seen that the pull-down structure of the Au film 6122 in the lid material 22 is effective in reducing peeling of the lid and poor airtightness due to the wraparound of the alloy formed by the eutectic bonding. Further, it can be seen that the pull-down width in this pull-down structure can exhibit its effect if it is at least 25 μm or more.

Further, from a comparison of Conditions 30 to 35 in Table 3, it can be seen that the evaluation of discoloration differs depending on the metallization width of the Au film 6122 . That is, under conditions 31 and 32, the appearance evaluation of discoloration is "⊚" (the comprehensive evaluation is also "⊚"). "○" (Comprehensive evaluation is also "○"). This is because the widening of the metallization width of the Au film 6122 widens the area of the base film where the adhesion strength is high, and the crystal lid 12 and the ceramic package 11 are bonded to the outer region of the light emitting device 10 with high adhesion strength. It is thought that it was because it was joined. That is, in the light-emitting device 10, the area to be bonded with high adhesion is widened, so that the crystal lid 12 and the ceramic package 11 are more likely to be affected by the difference in thermal expansion. It is considered that discoloration is more likely to occur compared to .

In conditions 33 to 35, in which the metallization width of the Au film 6122 is narrower than conditions 31 and 32, the narrower the metallization width, the lower the discoloration appearance evaluation and the overall evaluation. This is because if the metallization width of the Au film 6122 becomes too narrow, the area of the base film with high adhesion becomes small, and the lid cannot sufficiently withstand the difference in thermal expansion between the crystal lid 12 and the ceramic package 11 . It is thought that this is because peeling is likely to occur.

Furthermore, from a comparison of Conditions 31 to 34 and Conditions 36 to 39 in Table 3, when the pulling width of the Au film 6122 is different between the inside and the outside, the outside pulling width is larger than the outside. It can be seen that the inset pattern (conditions 31 to 34) in which the pull-down width on the outside is larger than that on the inside is more preferable than (conditions 36 to 39). In other words, it has been found that the outer pattern is more susceptible to crystal cracking due to the thermal shock test than the inner pattern. This is because when the crystal lid 12 and the ceramic package 11 are bonded with high adhesion in the outer region of the light emitting device 10, they are likely to be affected by the difference in thermal expansion between the crystal lid 12 and the ceramic package 11. As a result, it is considered that crystal cracks are more likely to occur during the thermal shock test.

In the above description of the third embodiment, only the Au film 6122, which is the uppermost layer of the base film 61A, has a downward structure. However, the present invention is not limited to this, and any film other than the lowest layer film (that is, the Ti film 5111) of the base film 61A may be applied with a pull-down structure in the upper layer portion including the film. . For example, as shown in FIG. 12, a downward structure may be applied to the upper layer from the Au film 5112 .

The embodiments disclosed this time are exemplifications in all respects and are not grounds for restrictive interpretation. Therefore, the technical scope of the present invention is not to be interpreted only by the above-described embodiments, but is defined based on the claims. In addition, all changes within the meaning and range of equivalence to the claims are included.

For example, in the above description, in the lid materials 20 to 22 of the light emitting device 10, the lid body is the crystal lid 12 as an example. However, the present invention is not limited to this, and quartz glass may be used for the lid body. That is, a conventional lid material using quartz glass uses a Cr film as the base film. It was confirmed that better performance was obtained in terms of film peeling and adhesion. It is considered that this is because the change of the base film from the Cr film to the base film 41A, 51A or 61A suppressed the diffusion of Au and Sn as brazing materials.

Further, in the light-emitting device 10 described above, the bonding layer 14 that bonds the ceramic package 11 and the crystal lid 12 is formed over substantially the entire surface of the frame-shaped bonding surface of the ceramic package 11 and the crystal lid 12 (in the width direction of the frame). are formed without bias against However, the present invention is not limited to this, and as shown in FIG. may In this way, when the bonding layer 14 is formed on the inner peripheral side with respect to the bonding surface, it is possible to reduce the influence of stress due to the difference in thermal expansion between the ceramic package 11 and the crystal lid 12, and cracking of the lid occurs. becomes difficult.

Furthermore, in the light emitting device 10 described above, the ceramic package 11 has a U-shaped stepped surface and the crystal lid 12 has a flat plate shape in order to seal the LED 13 in the package. However, the present invention is not limited to this, and like a light emitting device 10' shown in FIG. You may form the package which seals. Even in this case, the bonding layer 14 that bonds the ceramic base 11' and the stepped U-shaped crystal lid 12' can have the same structure as the light emitting device 10 described above.

10, 10' light emitting device 11 ceramic package (package base)
11' ceramic base (package base)
111 cavity 12, 12' crystal lid (lid body)
13 LED chip 14 bonding layers 20, 21, 22 lid material 30 package material 41, 51, 61 first metallized films 41A, 51A, 61A base film (base film of lid material)
41B Brazing material 42 Second metallized films 411, 511 First metal layer (first layer)
5111 Ti film 5112 Au film (buffer film)
5113 Ti film (buffer film)
412, 612 second metal layer 4121, 6121 Ni—Ti film 4122, 6122 Au film 43 alloy layer (second layer)

Claims (16)

A lid material used in a light-emitting device in which an LED is sealed in a package,
a lid body having transparency to the light emitted from the LED;
a first metallized film formed on the sealing surface of the lid body;
the first metallization film includes a first layer formed directly on the lid body and a second layer formed on the first layer;
The first layer is a layer containing a Ti film with a thickness of 20 to 700 nm,
A lid material, wherein the second layer has an alloy film containing Ni, Ti, Au and Sn. The lid material according to claim 1,
The lid material, wherein the Ti film included in the first layer is a Ti film with a film thickness of 200 to 300 nm. The lid material according to claim 1 or 2,
A lid material, wherein the first layer has an oxide film made of titanium oxide on its surface. The lid material according to any one of claims 1 to 3,
A lid material, wherein the first layer has a buffer film composed of an Au film and another Ti film laminated in order from a side close to the Ti film on the Ti film. The lid material according to any one of claims 1 to 4,
The second layer has Ni alloy films on its inner peripheral edge side and outer peripheral edge side, and the alloy films containing Ni, Ti, Au and Sn are formed between these Ni alloy films. lid material. The lid material according to any one of claims 1 to 5,
A lid material, wherein the lid body is made of crystal. A method for manufacturing a lid material used in a light-emitting device in which an LED is sealed in a package,
As a step of forming a base film on the sealing surface of the lid body having transparency to the irradiation light of the LED,
a first step of forming a first layer containing a Ti film having a thickness of 20 to 700 nm on the sealing surface of the lid body;
a second step of oxidizing the Ti film on the uppermost layer of the first layer formed in the first step to form an oxide film made of titanium oxide on the surface;
a third step of forming, on the first layer after the second step, a second layer containing a Ni alloy film and an Au film laminated in order from the side closer to the first layer;
and a fourth step of fusing a brazing material formed as an Au—Sn preform onto the Au film formed in the third step. A method for manufacturing a lid material according to claim 7,
A method of manufacturing a lid material, wherein the Ti film formed in the first step has a film thickness of 200 to 300 nm. A method for manufacturing the lid material according to claim 7 or 8,
A method of manufacturing a lid material, wherein in the first step, a buffer film composed of an Au film and another Ti film, which are laminated in order from the side nearer to the Ti film, is formed on the Ti film. A method for manufacturing a lid material according to any one of claims 7 to 9,
wherein the base film has a recessed structure at an upper layer portion including the arbitrary film in any film except for the lowest film,
In the pull-down structure, the inner peripheral edge of the film included in the pull-down structure is pulled down to the outside of the inner peripheral edges of the other films, and the outer peripheral edge of the film included in the pull-down structure is pulled down to the inside of the outer peripheral edges of the other films. A manufacturing method of a lid material, characterized in that the lid material is formed by being pulled down. A method for manufacturing a lid material according to any one of claims 7 to 10,
A method of manufacturing a lid material, wherein the lid body is made of crystal. A light-emitting device in which an LED is sealed in a package,
the LED;
a package base housing the LED in a cavity;
and a lid material for sealing the cavity opening of the package base,
A light-emitting device, wherein the lid material is the lid material according to any one of claims 1 to 6. 13. A light emitting device according to claim 12,
The light emitting device, wherein the package base is made of aluminum nitride. 14. The light-emitting device according to claim 12 or 13,
The light-emitting device, wherein the LED is a deep-ultraviolet LED. The light emitting device according to any one of claims 12 to 14,
The package base and the lid material are bonded via a bonding layer,
The bonding layer has a first layer, a second layer, a third layer, and a fourth layer formed in order of proximity to the lid body,
The first layer is a layer formed directly on the lid body and containing a Ti film having a thickness of 20 to 700 nm,
The second layer is an alloy layer containing Ni, Ti, Au and Sn,
The third layer is an alloy layer containing Ni, Ti, Au and Sn and having a lower Au content than the second layer,
The light-emitting device, wherein the fourth layer is a Ni-plated layer. 16. A light emitting device according to claim 15,
The light-emitting device, wherein the second layer is an alloy layer in a eutectic state, and the third layer is an alloy layer in a non-eutectic state.

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