JP2010089993A - Method for joining two members, and joined body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for obtaining a joined body of two members which is stable with the lapse of time. <P>SOLUTION: An SiO<SB>2</SB>thin film is grown on the joining face of a first member so as to be a thickness of 10 nm to 10 μm by a suitable thin film forming means, then, the SiO<SB>2</SB>thin film is immersed into an acid solution or an alkali solution, and, in the acid solution or alkali solution, the surface of the SiO<SB>2</SB>thin film is pasted with a second base material so as to form a pasted body. Thereafter, the pasted body is held at a prescribed temperature under prescribed atmospheric pressure for a prescribed time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for forming a joined body of two members of the same kind or different kinds, and particularly to a technique for forming a joined body of two flat members of the same kind or different kinds.

  When two members of the same type or different types are joined, an appropriate method is selected according to the type of member to be joined. For example, by using an adhesive made of an epoxy or acrylate resin composition having a fluorene skeleton for forming an adhesive layer, a method of obtaining a joined body of a thin base material having a thickness of 10 μm or less and another base material (for example, Patent Document 1), and a technique (for example, Patent Document 2) in which bulk glass is directly alkali-bonded to bulk glass or other materials are known.

  Also known is a method for manufacturing a piezoelectric thin film device, which includes a step of bonding a film-forming surface of a piezoelectric ceramic substrate on which an electrode film and an indicator film are formed with another piezoelectric ceramic substrate with an adhesive (for example, And Patent Document 3).

JP 2002-337274 A JP 2007-63055 A JP 2007-228319 A

Patent Document 1 discloses a case where base materials of lithium niobate (LiNbO ₃ ) and lithium tantalate (LiTaO ₃ ) are joined together.

In Patent Document 3, as a piezoelectric ceramic substrate, quartz (SiO ₂ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), lithium tetraborate (Li ₂ B ₄ O ₇ ), oxidation Examples include zinc (ZnO), potassium niobate (KNbO ₃ ), and langasite (La ₃ Ga ₃ SiO ₁₄ ). In the device manufacturing process, the other substrate is attached to the thin film forming surface of one substrate with an epoxy adhesive or acrylic. It is stated that they are bonded together with an adhesive.

  However, when bonding is performed with an adhesive as disclosed in Patent Document 1 and Patent Document 3, the thickness of the adhesive layer formed with the adhesive is not necessarily uniform, and the in-plane direction of the adhesive surface Can have a distribution. The existence of such a thickness distribution is not preferable because it causes an unnecessary electric field distribution, dielectric constant distribution, frequency distribution, and the like in a functional device as disclosed in Patent Document 3, and causes deterioration in device characteristics.

  On the other hand, Patent Document 2 discloses a method of joining a bulk glass having a size at least enough to form a microchip to another member, and two members that are not bulk glass. Patent Document 2 discloses nothing about the bonding and the mode of forming a bonded body with a bonding layer interposed therebetween.

  Further, when a joined body is formed by joining two members, it is desired that the joining is stable over time as a general and universal requirement. In addition, it has been confirmed by the inventor of the present invention that the glass bonded body manufactured by the method disclosed in Patent Document 2 deteriorates with time as time passes. Specifically, it has been confirmed that the bonding strength decreases and is easily peeled off, and that the higher the storage temperature, the lower the bonding strength and the easier the peeling.

  The present invention has been made in view of the above problems, and an object thereof is to provide a technique for obtaining a joined body of two members that is stable over time.

To solve the above problems, a first aspect of the invention, a method of joining two members, and SiO ₂ thin film formation step of growing a SiO ₂ thin film on the bonding surface of the first member, said SiO ₂ A dipping step of immersing the thin film in an acid solution or an alkali solution, a laminating step of laminating a _second substrate on the surface of the SiO ₂ thin film in the acid solution or alkaline solution, and forming a bonded body; A holding step of holding the bonded body at a predetermined temperature and atmospheric pressure.

A second aspect of the present invention is the bonding method according to the first aspect, wherein the SiO ₂ thin film is a crystalline thin film.

A third aspect of the invention is the bonding method according to the first or second aspect, wherein the SiO ₂ thin film is formed to a thickness of 10 nm or more and 10 μm or less.

A fourth aspect of the present invention is the bonding method according to the third aspect, wherein the SiO ₂ thin film is formed to a thickness of 100 nm to 1 μm.

The invention according to claim 5 is the bonding method according to any one of claims 1 to 4, wherein a metal thin film layer is formed on the bonding surface of the first member, and the SiO ₂ thin film is formed. In the forming step, the SiO ₂ thin film is formed on the metal thin film layer.

A sixth aspect of the present invention is the bonding method according to the fifth aspect, wherein the metal thin film layer is patterned, and the SiO ₂ thin film forming step includes the non-formation portion of the metal thin film layer. The SiO ₂ thin film is formed on the joint surface of one member.

  A seventh aspect of the present invention is the joining method according to any one of the first to sixth aspects, wherein at least one of the first and second members is a flat plate member.

  The invention of claim 8 is the bonding method according to any one of claims 1 to 7, wherein at least one of the first and second members is a ceramic single crystal substrate, a glass substrate, or a silicon single piece. It is one of crystal substrates.

The invention of claim 9 is a joined body in which two members are joined by a joining layer, wherein the joining layer is a SiO ₂ thin film grown on the joining surface of the first member, and the joining of the second member The surface and the SiO ₂ thin film are directly bonded to each other.

A tenth aspect of the present invention is the joined body according to the ninth aspect, wherein the SiO ₂ thin film is a crystalline thin film.

An eleventh aspect of the invention is the bonded body according to the ninth or tenth aspect, wherein the SiO ₂ thin film is formed to a thickness of 10 nm to 10 μm.

A twelfth aspect of the invention is the bonded body according to the eleventh aspect, wherein the SiO ₂ thin film is formed to a thickness of 100 nm to 1 μm.

A thirteenth aspect of the present invention is the joined body according to any one of the ninth to twelfth aspects, wherein a metal thin film layer is formed on the one main surface of the first member, and the metal thin film The SiO ₂ thin film is formed on the layer.

The invention according to claim 14 is the joined body according to claim 13, wherein the metal thin film layer is patterned, and the first main surface of the first member including a non-formed portion of the metal thin film layer is formed. The SiO ₂ thin film is formed on the substrate.

  A fifteenth aspect of the invention is the joined body according to any one of the ninth to fourteenth aspects, wherein at least one of the first member and the second member is a flat plate member.

  A sixteenth aspect of the invention is the joined body according to any one of the ninth to fifteenth aspects, wherein at least one of the first and second members is a ceramic single crystal substrate, a glass substrate, or a silicon single piece. It is one of crystal substrates.

  The invention of claim 17 is characterized in that a joined body of two members is produced by the joining method according to any one of claims 1 to 8.

According to the inventions of claims 1 to 17, when a joined body of two members of the same kind or different kinds is formed, the SiO ₂ thin film as a joining layer for joining the _two members is joined to one member by a thin film forming method. While being formed on the surface, the other member and the SiO ₂ film are directly bonded to each other, whereby a bonded body having excellent bonding strength over time can be obtained.

<First Embodiment>
<Structure and production method of joined body>
FIG. 1 is a cross-sectional view showing the structure of a joined body 10A produced by the method according to the first embodiment of the present invention. Note that the ratios of the sizes of the base material and the bonding layer in FIG. 1 and the subsequent drawings do not reflect actual ones.

In the joined body 10A shown in FIG. 1, the first base material 1 and the second base material 2 which are flat plate members S are joined by a joining layer 3 which is a thin film layer made of silicon dioxide (SiO ₂ ). It has a structure.

  FIG. 2 is a diagram showing the flow of the method for manufacturing the joined body 10A.

  First, two flat members S to be the first base material 1 and the second base material 2 are prepared (step S1).

As the flat member S, quartz (SiO ₂ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), lithium tetraborate (Li ₂ B ₄ O ₇ ), zinc oxide (ZnO), niobic acid Various single crystal substrates such as potassium (KNbO ₃ ) and langasite (La ₃ Ga ₃ SiO ₁₄ ), a quartz glass substrate, a silicon single crystal substrate, and the like can be used.

  The flat plate member S used for the first base material 1 and the flat plate member S used for the second base material 2 do not have to be made of the same kind of material, and different materials are used for the first base material. The mode used for 1 and the 2nd substrate 2 may be sufficient.

  In addition, the thickness of the first base material 1 and the second base material 2 is not particularly limited as long as the joined body 10A can be substantially formed, but for the convenience of handling, the thickness is about several hundred μm to several mm. It is preferable to Moreover, the thickness of the 1st base material 1 and the 2nd base material 2 does not need to be the same, Moreover, after formation of 10A of joined bodies, either or both are thinned by grinding | polishing, an etching, etc., and about several micrometers It is also possible to adopt a mode in which the thickness or a smaller submicron order thickness is provided.

  From the viewpoint of ensuring sufficient bonding strength, the flat plate member S used as the first base material 1 and the second base material 2 has a bonding surface (surface in contact with the bonding layer 3) substantially at the atomic level. It is preferable to have flatness. For example, it is preferable that the surface roughness Ra of the bonded surface measured with an AFM (atomic force microscope) is in the range of 0.1 nm to 50 nm.

When two flat plate members S can be prepared, the bonding layer 3 and the bonding layer 3 are formed on one main surface (bonding surface) of the flat plate member S used as the first substrate 1 after forming the bonded body 10A. A SiO ₂ film to be formed is grown (step S2). The thickness of the SiO ₂ film takes into consideration the bonding strength required when using the bonded body 10A, the types of members used as the first base material 1 and the second base material 2, the strength of the bonding layer 3 itself, and the like. Then, it may be determined appropriately. For example, it is preferably formed to have a thickness of 10 nm to 10 μm. If the thickness is smaller than this range, it is difficult to ensure the strength of the SiO ₂ film itself. Moreover, beyond the above range is not preferable and possible to form the SiO ₂ film is made to form a more SiO ₂ film which is required to ensure the function of the adhesive layer 3, consider the cost, etc. . Alternatively, when the joined body 10A is used as a functional device, there is a possibility that the presence of an SiO ₂ film having a thickness more than necessary may adversely affect device characteristics. More preferably, the SiO ₂ film is formed to have a thickness of 100 nm to 1 μm. Note that the thickness of the bonding layer 3 in the completed bonded body 10A is substantially the same as the thickness of the formed SiO ₂ film.

As a method for forming the SiO ₂ film, various thin film forming methods such as a vapor deposition method, a CVD method, a sol-gel method, and a sputtering method can be applied. However, when an impurity element such as an alkali element is mixed in the SiO ₂ film, it causes a deterioration in the bonding strength. Therefore, the SiO ₂ film is formed by a technique that does not cause such mixing as much as possible.

In addition, in any of the thin film formation methods, it is preferable that the SiO ₂ film is formed as a crystalline film, but it is possible to sufficiently suppress the mixing of impurities that cause deterioration of the bonding strength. For example, it may be formed as an amorphous film.

When the formation of the SiO ₂ film is completed in this way, the flat plate member S (first base material 1) on which the SiO ₂ film is formed is immersed and held in an acid solution or an alkali solution (step S3). . A hydrofluoric acid (HF) aqueous solution or the like can be used as the acid solution, and a potassium hydroxide (KOH) aqueous solution or the like can be used as the alkaline solution. When using a potassium hydroxide (KOH) aqueous solution, it is preferable to use a solution having a concentration of about 5 wt% to 40 wt%. Such dipping is performed for the purpose of softening the SiO ₂ film to develop adhesiveness. Therefore, the immersion may be performed in a time range necessary for sufficient adhesion to the SiO ₂ film. If the state in which the SiO ₂ film is sufficiently immersed in an acid solution or an alkali solution is realized, the entire first substrate 1 does not necessarily need to be immersed in an acid solution or an alkali solution, and at least SiO 2 It is only necessary to realize a state in which the _two membranes are immersed in an acid solution or an alkaline solution.

After a predetermined immersion time has elapsed, one main surface (bonding) of the flat plate member S to be the second substrate 2 is formed on the surface of the SiO ₂ film formed on the first substrate 1 in an acid solution or an alkaline solution. The first base material 1 and the second base material 2 are bonded to each other in a form in which the surfaces are stacked (step S4).

  Then, while maintaining the bonded state, the bonded body is pulled up from the acid solution or the alkaline solution, and the temperature is 60 ° C. to 150 ° C. and the atmospheric pressure is 0.6 MPa to 2 MPa. It is made to dry by hold | maintaining (step S5).

As a result, direct bonding between the SiO ₂ film and the second substrate 2 is realized, and as a result, the bonding in which the SiO ₂ film becomes the bonding layer 3 and the first substrate 1 and the second substrate 2 are bonded. A body 10A is produced.

<Stability of bonding strength of bonded body over time>
The joined body 10 </ b> A obtained by the above-described procedure can obtain good stability of the joining strength over time. This can be confirmed, for example, by performing a peeling test on the joined body 10A after a predetermined time has elapsed after fabrication. As an example, when a peel test is performed after 24 hours have elapsed after fabrication of a bonded body in which one base material is a LiNbO ₃ single crystal substrate and the other base material is a quartz glass substrate, it is peeled off at the bonding interface. It has been confirmed by the inventor of the present invention that the base material destruction in which the flat plate member S constituting the first base material 1 or the second base material 2 is broken occurs (see Example 1). ). That is, the joining of the flat plate member S as the first base material 1 and the SiO ₂ film formed by the thin film formation technique, and the direct joining of the SiO ₂ film and the flat plate member S as the second base material 2 are performed. As for all, 10 A of joined bodies are produced as what has sufficient joint strength.

Further, as described so far, the joined body 10A manufactured in the present embodiment is formed by interposing a joining layer between two flat members S, and one flat plate shape. A SiO ₂ film serving as a bonding layer is grown on the main surface of the member, and then one flat plate member S is directly bonded to the SiO ₂ film. Therefore, it has a different structure from the joined body obtained by alkali-bonding bulk glass with another member as disclosed in Patent Document 2. In the case of a joined body manufactured by the technique according to Patent Document 2, a joined body 10A according to the present embodiment (for example, as described above, a LiNbO ₃ single crystal substrate and a quartz glass substrate are used as base materials, and SiO ₂ It is difficult to obtain sufficient temporal stability equivalent to that of a bonded body provided with a thin film as a bonding layer.

This is because bulk glass usually contains a considerable amount of alkali elements as impurity elements, and in a joined body in which bulk glass is directly alkali-bonded to other members, the impurity elements diffuse in the bulk glass. This is because the segregation is gradually segregated at the joint interface, and as a result, the strength of the joint interface decreases with time. On the other hand, in the bonded body 10A according to the present embodiment having the SiO ₂ film formed by the thin film forming method as described above as the bonding layer 3, such an impurity element is hardly mixed. Therefore, the bonding strength is not deteriorated due to the mixing of the impurity element.

In other words, in the present embodiment, it can be said that sufficient temporal stability is ensured by using a SiO ₂ thin film containing no impurity element for direct bonding.

As described above, according to the present embodiment, when forming a bonded body of the same or different types of flat plate members, the SiO ₂ film as a bonding layer for bonding the _two is formed on one flat plate by a thin film forming method. By forming the _second flat member and the SiO ₂ film directly after forming on the main surface of the member, it is possible to obtain a joined body having excellent bonding strength over time.

<Second Embodiment>
In the first embodiment, the description is made for the joined body in which both of the two base materials are the flat members S. However, the aspect in which the SiO ₂ thin film is used as the joining layer is not limited thereto. . In the following description, the same components as those of the joined body 10A according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 3 is a diagram showing the structures of two types of joined bodies produced by the method according to the second embodiment of the present invention.

  FIG. 3A is a cross-sectional view showing the structure of one joined body 10B. In the joined body 10B, the first base material 1 in which the thin film layer F is formed on the flat plate member S and the second base material 2 made of the flat plate member S include the thin film layer F between both base materials. It has the structure joined by the joining layer 3 in the aspect to interpose.

  FIG. 3B is a cross-sectional view showing the structure of the other joined body 10C. In the joined body 10C, the first base material 1 on which the patterned thin film layer F is formed on the flat plate member S and the second base material 2 made of the flat plate member S are used as the two base materials. In addition, the structure is joined by the joining layer 3 formed corresponding to the patterning of the thin film layer F. The thin film layer F is a metal thin film made of, for example, aluminum (Al).

  That is, both the bonded bodies 10B and 10C are common in that the first base material 1 is a flat member S provided with the thin film layer F, and whether or not the thin film layer F is patterned. It is different in point.

  FIG. 4 is a diagram showing the flow of the manufacturing method of the bonded body 10B and the bonded body 10C.

  Also in the present embodiment, the point that two flat members S are prepared is the same as in the first embodiment (step S1), but a thin film layer F is formed on one flat member S. This is different from the first embodiment in that the first substrate 1 is obtained (step S1β).

  The thin film layer F is formed with an appropriate thickness according to the function and application of the joined body 10B and the joined body 10C. For example, it is formed to a thickness of about 20 nm to 1 μm.

  As a method for forming the thin film layer F, various thin film forming methods such as sputtering, vapor deposition, and CVD can be applied. When patterning is performed as in the bonded body 10C, a known photolithography process can be used.

In this manner, when the first substrate 1, a thin film layer F is formed is obtained, on the surface on which the thin film layer F of the first substrate 1 is formed, similarly to the first embodiment SiO ₂ A film is formed (step S2). When the joined body 10C is formed, a step due to the patterning of the thin film layer F may occur on the upper surface of the obtained SiO ₂ film. In this case, the SiO ₂ film has a SiO ₂ so that the step is eliminated. _{The two} films are preferably polished from the upper surface side by a predetermined thickness. More preferably, the upper surface of the SiO ₂ film has substantially flatness at the atomic level. For example, it is preferable that polishing is performed so that the value of the surface roughness Ra measured with an AFM (atomic force microscope) is in the range of 0.1 nm to 50 nm.

After the formation (and polishing) of the SiO ₂ film, the substrate is immersed in an acid solution or an alkali solution (step S3) and pasted in the liquid, similarly to the method of manufacturing the bonded body 10A according to the first embodiment. The bonding (step S4) and the holding and drying (step S5) of the bonded body under a predetermined temperature and atmospheric pressure may be sequentially performed.

  From the above procedure, the joined body 10B and the joined body 10C are produced.

Also in the joined body 10B and the joined body 10C produced in this way, the stability of the joining strength over time can be satisfactorily obtained. Similar to the first embodiment, this can be confirmed by performing a peeling test on the joined body 10B and the joined body 10C after a predetermined time has elapsed after the production. That is, the bonding of the thin film layer F and the flat plate member in the first substrate 1, the bonding of the thin film layer F and the SiO ₂ film, and the bonding of the SiO ₂ film and the flat plate member as the second substrate 2. In any case, the bonded body 10B and the bonded body 10C are manufactured so as to have sufficient bonding strength.

As described above, according to the present embodiment, even if a thin film layer is formed on the surface of one base material, the SiO ₂ film is formed as a bonding layer by the thin film formation method on one base material. By forming them directly and joining them directly, it is possible to obtain a joined body of ceramic single crystal substrates having excellent temporal strength stability of the joining strength.

<Modification>
In each of the above-described embodiments, the case where the member used for forming the joined body is a flat plate is described as an object. However, if the joining surface is flat enough to be joined, the member The shape may not be flat.

Example 1
In this example, a joined body 10A according to the first embodiment was produced. As the flat member S, a LiNbO ₃ single crystal substrate and a quartz glass substrate each having a diameter of 3 inches and a thickness of 0.5 mm were prepared. About each, the joint surface was grind | polished until surface roughness Ra became 2 nm.

A LiNbO ₃ single crystal substrate was used as the first base material 1, and a SiO ₂ film having a thickness of 500 nm was formed on the bonding surface by sputtering, and then immersed in an aqueous potassium hydroxide solution having a concentration of 5 wt% for 5 minutes.

After 5 minutes, in the aqueous potassium hydroxide solution, the bonded surface of the quartz glass substrate as the second substrate 2 was bonded onto the SiO ₂ film formed on the first substrate 1. This temporary bonded state was pulled up from the aqueous potassium hydroxide solution and held for 12 hours under the conditions of 65 ° C. and 0.6 Mpa to obtain a joined body 10A.

  A peel test was performed on the obtained bonded body 10A. As a result, the base material was broken and no breakage occurred at the joint surface.

  Moreover, about the joined body 10A produced on the same conditions, also when the high temperature holding test of temperature 120 degreeC was performed for 2000 hours, and the same peeling test was done after that, it was the same result.

(Example 2)
In this example, a joined body 10B according to the second embodiment was produced. As the flat member S, two LiTaO ₃ single crystal substrates each having a diameter of 3 inches and a thickness of 0.5 mm were prepared. About each, the joint surface was grind | polished until surface roughness Ra became 2 nm.

On one LiTaO ₃ single crystal substrate, a ruthenium film as a thin film layer F is formed to a thickness of 200 nm by a sputtering method to obtain a first base material 1, and then a SiO method is formed on the ruthenium by a CVD method. _Two films were formed to a thickness of 500 nm.

  Thereafter, a joined body 10B was obtained in the same procedure as in Example 1.

  As a result of performing a peeling test on the obtained bonded body 10B, the base material was broken and no breakage occurred on the bonded surface.

  Moreover, the same result was obtained when the bonded body 10B manufactured under the same conditions was further subjected to a high temperature holding test at a temperature of 120 ° C. for 2000 hours, and then a similar peeling test was performed.

(Example 3)
In this example, a joined body 10C according to the second embodiment was produced. As the flat member S, a Si single crystal substrate and a quartz single crystal substrate each having a diameter of 3 inches and a thickness of 0.5 mm were prepared. For the Si single crystal substrate, the bonding surface was polished until the surface roughness Ra was 2 nm.

After forming a ruthenium film as a thin film layer F to a thickness of 200 nm by sputtering on the entire surface of the quartz single crystal substrate, patterning is performed by photolithography to obtain the first substrate 1, and then the ruthenium. A SiO ₂ film having a thickness of 1000 nm was formed thereon by a sol-gel method.

The SiO ₂ film was polished by 500 nm from the surface side, the step of the pattern outline of the thin film layer F was eliminated, and the surface roughness Ra of the SiO ₂ film was 2 nm.

  Thereafter, a joined body 10C was obtained in the same procedure as in Example 1.

  As a result of performing a peeling test on the obtained bonded body 10C, the base material was broken and no breakage occurred on the bonded surface.

  Moreover, about the joined body 10C produced on the same conditions, when the high temperature holding test of 120 degreeC was further performed for 2000 hours, and the same peeling test was done after that, it was the same result.

(Comparative Example 1)
In this comparative example, a joined body of a LiTaO ₃ substrate and a silicon substrate was obtained by a method similar to the method disclosed in Patent Document 1.

Specifically, first, a 1 mm thick LiTaO ₃ substrate cut into a 15 mm square is prepared, a 1 mm thick silicon substrate cut into a 20 mm square is prepared, and an acrylate resin having a fluorene skeleton (hereinafter referred to as an adhesive) is used. The cardo acrylate resin (V-259PA) manufactured by Nippon Steel Chemical Co., Ltd. was prepared. The resin was prepared so as to have a viscosity of 70 cps.

After the LiTaO ₃ substrate and the silicon substrate were washed, the resin was dropped on the main surface of the silicon substrate, and the LiTaO ₃ substrate was laminated and pressed to perform bonding. The obtained bonded body was heated at 100 ° C. for 1 hour to temporarily cure the resin, and further heated at 200 ° C. for 1 hour to cure the resin and obtain an adhesive. The thickness of the adhesive layer was 0.2 μm.

  FIG. 5 is a diagram showing the results of observation of the obtained bonded body with a laser interferometer. From the observation result shown in FIG. 5, it is confirmed that the adhesive layer has a thickness distribution in a bowl shape. That is, it was confirmed that the thickness of the adhesive layer becomes non-uniform when bonding is performed by the method according to this comparative example.

  Further, the bonded body was put into a high temperature holding test to evaluate the bondability. The conditions were a temperature of 120 ° C. and a test time of 200 hours.

  When the joined body after the test was visually observed, white turbidity was found on the joined surface. Moreover, FIG. 6 is a figure which shows the observation image about the cross section of the adhesive body before and behind a test. 6A is an image before the test, and FIG. 6B is an image after the test. From the image shown in FIG. 6B, it was confirmed that peeling occurred in the adhesive layer of the adhesive after the test.

  This result indicates that the bonded body manufactured by the method according to Patent Document 1 is deteriorated with time in the bonding strength.

(Comparative Example 2)
In this comparative example, a joined body of glass was obtained by the same method as the method disclosed in Patent Document 2. In this comparative example, two quartz glass substrates each having a diameter of 3 inches and a thickness of 0.5 mm were prepared as flat members. About each, the joint surface was grind | polished until surface roughness Ra became 2 nm.

  Two quartz glass substrates were immersed in an aqueous potassium hydroxide solution having a concentration of 5 wt% for 5 minutes.

  After 5 minutes, the bonded surfaces of the quartz glass substrates were bonded together in an aqueous potassium hydroxide solution. The temporary bonded state was pulled up from the aqueous potassium hydroxide solution and held for 12 hours under the conditions of 65 ° C. and 0.6 Mpa to obtain a joined body.

  The bonded body was subjected to a high temperature holding test under a condition where the holding temperature and holding time were changed to a plurality of times, and a bonding strength test after the test was performed.

  A blade test was conducted as a joint strength test of the joined body. This test is a method for evaluating the bonding strength by inserting a knife edge at the end of the bonded surface of the bonded body and measuring the distance at which the separation peels from the end. It can be evaluated that the shorter the peeling extension distance, the stronger the bonding strength, and the longer the peeling extension distance, the weaker the bonding strength.

  FIG. 7 is a diagram showing a result of a blade test for a joined body according to this comparative example. FIG. 7 shows the relationship between the high temperature holding time and the peel extension distance. The bonded body with a holding temperature of 120 ° C. had a peel-extension distance of 15.5 mm at a holding time of 160 hours, but the substrate was easily peeled off when the bonded body was handled, and the bonding strength was hardly maintained. It was completely detached. Similarly, when the holding time was 100 ° C., the holding time was 240 hours, and when the holding temperature was 80 ° C., the peeling was completed after 400 hours. From this result, it can be seen that as the holding time in the high-temperature holding test becomes longer, the bonding strength gradually decreases and eventually peels, and as the test temperature increases, the strength decreases and peels faster. The result shows that the joined body according to this comparative example does not have sufficient joint strength as the joined body according to each of the above-described examples.

It is sectional drawing which shows the structure of 10 A of joined bodies produced with the method which concerns on 1st Embodiment. It is a figure which shows the flow about the preparation methods of 10 A of joined bodies. It is a figure which shows the structure of two types of conjugate | zygote produced with the method concerning the 2nd Embodiment of this invention. It is a figure which shows the flow about the manufacturing methods of joined body 10B and joined body 10C. It is a figure which shows the result of having observed the adhesive body which concerns on the comparative example 1 with the laser interferometer. It is a figure which shows the observation image about the cross section of the adhesive body before and behind a HAST test about the adhesive body which concerns on the comparative example 1. FIG. It is a figure which shows the result of the blade test about the conjugate | zygote which concerns on the comparative example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st base material 2 2nd base material 3 Joining layer 10A, 10B, 10C joined body F Thin film layer S Flat plate-shaped member

Claims (17)

A method of joining two members,
And SiO ₂ thin film formation step of growing a SiO ₂ thin film on the bonding surface of the first member,
An immersion step of immersing the SiO ₂ thin film in an acid solution or an alkaline solution;
A bonding step of bonding a second base material to the surface of the SiO ₂ thin film to form a bonded body in the acid solution or the alkali solution;
A holding step of holding the bonded body at a predetermined temperature and atmospheric pressure;
A method for joining two members characterized by comprising: The joining method according to claim 1,
The SiO ₂ thin film is a crystalline thin film;
The joining method of two members characterized by the above-mentioned. The joining method according to claim 1 or 2,
The SiO ₂ thin film is formed to a thickness of 10 nm to 10 μm.
The joining method of two members characterized by the above-mentioned. The joining method according to claim 3,
The SiO ₂ thin film is formed to a thickness of 100 nm to 1 μm.
The joining method of two members characterized by the above-mentioned. A joining method according to any one of claims 1 to 4,
A metal thin film layer is formed on the joining surface of the first member,
In the SiO ₂ thin film forming step, the SiO ₂ thin film is formed on the metal thin film layer.
The joining method of two members characterized by the above-mentioned. The joining method according to claim 5,
The metal thin film layer is patterned,
In the SiO ₂ thin film forming step, the SiO ₂ thin film is formed on the bonding surface of the first member including a non-formed portion of the metal thin film layer.
The joining method of two members characterized by the above-mentioned. A joining method according to any one of claims 1 to 6,
At least one of the first and second members is a flat member,
The joining method of two members characterized by the above-mentioned. A joining method according to any one of claims 1 to 7,
At least one of the first and second members is either a ceramic single crystal substrate, a glass substrate, or a silicon single crystal substrate.
The joining method of two members characterized by the above-mentioned. A joined body in which two members are joined by a joining layer,
The bonding layer is a SiO ₂ thin film grown on the bonding surface of the first member;
The bonding surface of the second member and the SiO ₂ thin film are directly bonded.
A joined body of two members characterized by the above. The joined body according to claim 9,
The SiO ₂ thin film is a crystalline thin film;
A joined body characterized by that. The joined body according to claim 9 or 10,
The SiO ₂ thin film is formed to a thickness of 10 nm to 10 μm.
A joined body characterized by that. The joined body according to claim 11,
The SiO ₂ thin film is formed to a thickness of 100 nm to 1 μm.
A joined body characterized by that. A joined body according to any one of claims 9 to 12,
A metal thin film layer is formed on the one main surface of the first member,
The SiO ₂ thin film is formed on the metal thin film layer,
A joined body characterized by that. The joined body according to claim 13,
The metal thin film layer is patterned,
The SiO ₂ thin film is formed on the one main surface of the first member including a portion where the metal thin film layer is not formed,
A joined body characterized by that. A joined body according to any one of claims 9 to 14,
At least one of the first and second members is a flat member,
A joined body of two members characterized by the above. A joined body according to any one of claims 9 to 15,
At least one of the first and second members is either a ceramic single crystal substrate, a glass substrate, or a silicon single crystal substrate.
A joined body of two members characterized by the above.   A joined body of two members produced by the joining method according to any one of claims 1 to 8.