JP2021136413A - Sealing structure body and manufacturing method thereof - Google Patents

Abstract

To provide a sealing structure body and a manufacturing method thereof that can realize a simpler sealing process and a simpler sealing structure.SOLUTION: A sealing structure body 100 according to the present invention with a closed space S includes a first substrate 10 and a second substrate 20 having recesses 10A, a joint portion 30 that is arranged so as to surround the recess 10A and joins the first substrate 10 and the second substrate 20, and a getter layer 40 that is formed on the surface of the first substrate 10 that defines the closed space S, and absorbs gas in the closed space S, and the joint portion 30 includes a first metal element that can constitute the getter material, and the getter layer 40 includes a first metal element included in the joint portion 30 on the surface.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sealed structure and a method for producing the same.

In order to extend the life and accuracy of the MEMS device, it is necessary to seal the device with a high degree of vacuum and maintain the degree of vacuum for a long period of time.

In order to realize a high degree of vacuum sealing, it is necessary to join the sufficiently degassed substrates by using a highly airtight sealing portion (joining portion). In order to realize such sealing, a joining method using a multilayer metal film made of an adhesion material / diffusion barrier material / joining material at the joining portion has been proposed (Non-Patent Document 1). This method has an advantage that there are few restrictions on the substrate material that can be sealed and bonded because bonding is possible if an adhesive material such as Ti can be firmly bonded to the substrate surface. Further, in the bonding structure thus obtained, the diffusion barrier layer can suppress the thermal diffusion of the adhesive material to the surface during the degassing treatment by vacuum annealing, so that the bonding materials on the surface can be bonded to each other even after sufficient degassing. Airtight sealing can be achieved.

Further, there is known a method of arranging a member (getter material) capable of chemically reacting with an internal gas in the same closed space as the device and absorbing the gas after sealing to improve the degree of vacuum. In particular, a thin film containing an active material such as Ti, Zr, and V, which is called a getter layer, has an advantage of being smaller and lighter than other methods.

T.Matsumae et al. Microelectron. Eng. 197 (2018) 76-82

In order to obtain a good vacuum sealing structure, it is effective to use a joint portion capable of sealing after degassing treatment and a getter layer capable of absorbing gas after sealing. Since a material having both characteristics at the same time has not been realized, it is necessary to form separate material layers as a joint portion and a getter layer and pattern them in a desired shape. Therefore, in the manufacturing process of the sealing structure, the getter layer is formed and patterned, and the joint is formed and patterned separately, followed by degassing and sealing, and finally activation of the getter layer by annealing. There is a problem that the number of steps increases because gas is absorbed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sealing structure capable of realizing a simpler sealing process and a simpler sealing structure, and a method for manufacturing the same.

The present invention provides the following means for solving the above problems.

(1) The sealing structure according to the first aspect of the present invention is a sealing structure having a sealed space, and surrounds the first substrate and the second substrate having recesses in at least one of them, and the recesses. A joint portion for joining the first substrate and the second substrate, and a part of the surface of the first substrate and the second substrate that define the enclosed space are formed in the above manner. A getter layer that absorbs gas in a closed space is provided, and the joint portion contains a first metal element that can form a getter material, and the getter layer contains the first metal element on its surface.

(2) In the sealing structure according to the above aspect, the first metal element may contain one of Ti, Cr, Zr, Nb and Ta.

(3) The sealing structure according to the above aspect may contain a second metal element in which the getter layer and the joint portion have a lower thermal diffusion mobility than the first metal element.

(4) In the sealing structure according to the above aspect, the second metal element may contain one of Pt, Co, Ru and W.

(5) In the sealing structure according to the above aspect, the getter layer may be formed on the entire inner surface of the recess.

(6) The method for manufacturing a sealing structure according to a second aspect of the present invention includes a first substrate having a recess, a second substrate, and the first substrate which is arranged so as to surround the recess. The sealed space is formed on a part of the surface of the first substrate among the first substrate and the second substrate that define the sealed space with the joint portion for joining the second substrate. A method for manufacturing a sealed structure including a getter layer that absorbs the gas inside, wherein a first base layer and a first base layer are formed on at least a joint portion of the first substrate and a surface on which the getter layer is formed. The step of forming the first laminated film by forming the surface layers in this order and the second layered film by forming the second base layer and the second surface layer on the surface of the second substrate in this order. At a first temperature in vacuum or under reduced pressure, the step of forming the first laminated film, the first substrate on which the first laminated film is formed, and the second substrate on which the second laminated film is formed are formed. The step of heating and degassing, the step of joining the first surface layer of the degassed first substrate and the second surface layer of the second substrate together, and the joining. The first substrate and the second substrate are heated at a second temperature to obtain a first metal element that can form a getter material that constitutes the first base layer of the first laminated film. Includes a step of thermally diffusing the surface to activate it as a getter layer.

(7) In the method for manufacturing the sealed structure according to the above aspect, a second substrate having a recess may be used.

(8) In the method for manufacturing a sealing structure according to the above aspect, a getter layer may also be formed on the surface of the recess of the second substrate.

(9) In the method for producing a sealed structure according to the above aspect, the first base layer may contain one metal of Ti, Cr, Zr, Nb and Ta or an alloy thereof.

(10) In the method for producing a sealing structure according to the above aspect, in the step of forming the first laminated film, the metal material of the first base layer is formed between the first base layer and the first surface layer. It may further include the step of forming an intermediate layer that prevents the diffusion of.

(11) In the method for producing a sealed structure according to the above aspect, the intermediate layer may contain one metal of Pt, Co, Ru and W or an alloy thereof.

(12) In the method for producing a sealed structure according to the above aspect, the film thickness of the intermediate layer may be set in the range of 5 nm to 20 nm.

(13) In the method for manufacturing a sealed structure according to the above aspect, the second temperature may be set higher than the first temperature.

(14) In the method for producing a sealed structure according to the above aspect, the first temperature is selected from the range of 100 ° C. to 400 ° C., and the second temperature is selected from the range of 350 ° C. to 600 ° C. May be good.

According to the sealing structure of the present invention, it is possible to provide a sealing structure capable of realizing a simpler sealing process and a simpler sealing structure.

(A) is a schematic cross-sectional view showing a sealing structure according to the first embodiment of the present invention, and (b) is an example of a sealing device in which a device is arranged in a sealed space of the sealing structure. It is a cross-sectional schematic diagram which shows. It is a cross-sectional schematic diagram for demonstrating the feature of the structure of the getter layer 40, (a) shows the structure of the getter layer before use or before the activation treatment, (b) is the getter layer is a gas. (C) shows the structure of the getter layer in the middle stage when the getter layer absorbs gas, and (d) shows the structure of the getter layer in the middle stage. It absorbs gas and shows the structure of the getter layer at the end. It is a figure for demonstrating the manufacturing method of the sealing structure of this invention, (a) shows the substrate preparation process, (b) shows the film forming process, (c). Indicates a degassing step, (d) shows a joining step, and (e) shows an activation step. It shows the XPS spectrum, (a) is for sample 1, and (b) is for sample 2. The step of producing the sealing structure of Example 1 is shown, (a) shows a film forming step, (b) shows a joining step, and (c) shows an activation step. Is shown. This is the result of elemental analysis by XPS in the depth direction of the getter layer formed on the inner wall of the recess of Example 1. It is an XPS spectrum of the Ti2p region in the depth direction of the getter layer. It is a transmission electron microscope (TEM image) of a getter layer. This is the result of elemental analysis mapping of the getter layer. This is the result of elemental analysis by XPS in the depth direction of the getter layer formed on the inner wall of the recess of Example 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, the same or equal parts may be designated by the same reference numerals in the drawings. Further, in the drawings used in the following description, the featured portion may be enlarged for convenience in order to make the feature easy to understand, and the dimensional ratio of each component is not always the same as the actual one. Further, the materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and can be appropriately modified and carried out within the range in which the effects of the present invention are exhibited. .. The configuration shown in one embodiment can also be applied to other embodiments.

FIG. 1A is a schematic cross-sectional view showing a sealing structure according to the first embodiment of the present invention. FIG. 1B is a schematic cross-sectional view showing an example of a sealing device in which the device is arranged in a sealed space of the sealing structure.

The sealing structure 100 shown in FIG. 1A is a sealing structure having a sealed space S, and surrounds the first substrate 10 and the second substrate 20 having the recesses 10A and the recesses 10A. It is formed on the surface of the first substrate 10 which is arranged and joins the first substrate 10 and the second substrate 20 and the first substrate 10 which defines the closed space S, and absorbs the gas in the closed space S. The getter layer 40 includes a getter layer 40, and the joint portion 30 contains a first metal element that can form a getter material, and the getter layer 40 contains a first metal element contained in the joint portion 30 on its surface.

[Sealing structure]
In the sealing device 101 shown in FIG. 1 (b), the device D is arranged on the second substrate 20 in the sealed space S of the sealing structure 100 shown in FIG. 1 (a).

In the sealing structure 100, the getter layer 40 is provided on the entire inner surface of the recess 10A, but it may be provided on a part of the inner surface.

In the sealing structure 100, the recess is provided only in the first substrate 10, but the second substrate 20 may also have the recess.
Further, when the second substrate 20 has a recess, a getter layer may be provided in the recess. In this case, the getter layer provided in the recess of the second substrate 20 may have a different configuration from the getter layer included in the recess of the first substrate 10. In this case, each getter layer can be configured to be suitable for adsorbing different gases.

The first metal element is a metal element that can be a component of the getter material, and preferably contains at least one of Ti, Cr, Zr, Nb, Ta, V, and Hf.

The getter layer 40 and the joint portion 30 may contain a second metal element having an impurity diffusion coefficient to the first surface layer (see reference numeral 11C in FIG. 2) lower than that of the first metal element. As the second metal element, it is preferable that the second metal element contains one metal of Pt, Co, Ru and W, or an alloy thereof. Here, the fact that the impurity diffusion coefficient to the first surface layer is lower than that of the first metal element means that the impurity diffusion coefficient when the atom of the second metal element diffuses into the metal of the metal element of the first surface layer. However, it means that it is smaller than the impurity diffusion when the atom of the first metal element diffuses into the metal of the metal element of the first surface layer. For example, since the impurity diffusion coefficient of Pt with respect to Au is smaller than the impurity diffusion coefficient of Ti with respect to Au, the Pt atom is less likely to move in the Au layer than the Ti atom diffuses and moves in the Au layer, which is unnecessary. Can prevent diffusion. The impurity diffusion coefficient can be obtained from known experimental data.
The impurity diffusion coefficient D is the Arrhenius equation.
D = D ₀ exp (-Q / RT)
It is represented by. D ₀ is the previous exponential term, Q is the activation energy, R is the gas constant, and T is the temperature (K).
Further, the distance L [m] at which the metal atom can be diffused during the time t [second] is determined by using the diffusion coefficient D.
L = √Dt
It can be expressed as. Based on this equation, for example, the thickness (5 nm) at which the Ti atom does not break the Pt diffusion barrier layer during the degassing treatment (200 ° C., 10 min) can be estimated.

Activation of the getter material means to develop a gas adsorption function. If gas is adsorbed on the surface of the getter material, the desired gas adsorption function cannot be exhibited. Therefore, the gas adsorption function can be exhibited by removing the adsorbed species on the surface of the getter material by heating (annealing) the getter material. In the present specification, adsorption is used when it means that the atoms constituting the getter layer and gas chemically react with each other, and absorption is used when it means that the getter layer takes in gas. ..

In the getter layer 40, the first metal element (the metal element that can form the getter material) constituting the getter layer 40 chemically adsorbs with the gas in the enclosed space to become a compound of the first metal element. Therefore, the structure of the getter layer 40 changes with time depending on the usage conditions of the sealing structure. Further, the structure of the getter layer 40 also varies depending on the conditions of the activation step when manufacturing the sealed structure.

FIG. 2 shows a schematic cross-sectional view for explaining the structural features of the getter layer 40.
As described above, since the structure of the getter layer of the sealing structure of the present invention has a characteristic of having variations depending on manufacturing conditions and usage conditions, the getter layer described with reference to FIGS. 2 (b) to 2 (d). The structure of is typical. FIG. 2A shows the structure before use or before the activation treatment.

FIG. 2A shows the structure of the getter layer before use or activation treatment. In the following, the first substrate 10 is a Si substrate having a thermal oxide film, and the first base layer 11A, the first intermediate layer 11B, and the first surface layer 11C constituting the laminated body 11 are a Ti layer and a Pt layer, respectively. , The case of the Au layer will be described as an example.

FIG. 2B shows the structure of the getter layer at the initial stage after the activation treatment is performed and the use is started, that is, the getter layer starts to absorb the gas. The Ti atoms constituting the first base layer (Ti layer) 11A, which is an adhesion layer with the substrate, break through the first intermediate layer (Pt layer) 11B by thermal diffusion by activation annealing and reach the surface, and gas (mainly). Reacts with water vapor to form a Ti compound (eg, TiO ₂ ). The layer represented by reference numeral 41A is a layer composed of a Ti compound (a compound of an active material). The getter layer 40 is a layer containing the first metal element (Ti) on its surface. The first surface layer (Au layer) 11C involved in joining the substrates is a layer 41C having a discontinuous portion in the activation treatment. In a plan view, the Ti compound layer 41 is exposed from the discontinuous portion of the Au layer 41C. The first intermediate layer (Pt layer) 11B, which is a diffusion barrier layer, is broken by thermal diffusion of Ti atoms to become a discontinuous layer 41B in the activation treatment, and is arranged directly under the Au layer 41C. The Ti layer 11AA remains under the Pt layer 41B. Further, a Si—Ti reaction layer 11AX is provided between the Si substrate 10 and the Ti layer 11AA.

FIG. 2C shows the structure of the getter layer in the middle stage after the activation treatment is performed and the getter layer absorbs gas. The Ti compound layer 41A absorbs gas and becomes thicker. The Au layer 41C is further discontinuous and has a structure in which it is mainly arranged in a granular manner on the surface. The Pt layer 41B is arranged below the Ti compound layer 41A, and since the Ti compound layer is formed near the surface, it is arranged at a position deep from the surface. The Ti layer 11AA is thinner due to the movement of Ti atoms to the surface by thermal diffusion.

FIG. 2D shows the structure of the getter layer at the final stage after the activation treatment is performed and the getter layer absorbs the gas. The Ti compound layer 41A absorbs gas and becomes thicker. The number of crystal grains arranged on the surface of the Au layer 41C is small, and the number of crystal grains arranged inside the Ti compound layer 41A is large. The Pt layer 41B is arranged at a position deeper than the surface because the Ti compound layer 41A is thicker. The Ti layer 11AA has almost disappeared because it has been thermally diffused as Ti atoms constituting the Ti compound layer 41A.

The joint portion 30 includes the same composition as the getter layer 40, but the getter layer absorbs gas to form a structure, whereas the joint portion 30 has a portion that does not come into contact with the gas in the enclosed space. In many cases, its structure can differ from the getter layer.

[Manufacturing method of sealed structure]
The method for producing the sealed structure of the present invention will be described by taking the case of producing the above-mentioned sealed structure as an example.

(Board preparation process)
A first substrate 10 having a recess 10A and a second substrate 20 are prepared (FIG. 3A).
As the first substrate and the second substrate, a field of material that can be used in a known sealing structure can be used. For example, silicon, sapphire, glass and the like can be used. A Si substrate having a thermal oxide film may be used.

(Film formation process)
The first base layer 11A, the first intermediate layer 11B, and the first surface layer 11C are formed in this order on the surface 10a of the first substrate 10 on the closed space side (FIG. 3B).

For the first base layer 11A, it is preferable to use a material suitable for adhering to the first substrate 10. In this sense, the first base layer functions as an adhesion layer, and the material constituting the first base layer is an adhesion material. The first base layer 11A contains a metal element (first metal element) that can form a known getter material. Here, the getter material is a material capable of adsorbing an _{active gas (O 2} , H ₂ O, CO, CO ₂ , N _{2, etc.) by a chemical reaction in vacuum.} The first metal element preferably contains at least one of Ti, Cr, Zr, Nb, Ta, V and Hf. The first base layer 11A may be made of at least one metal of Ti, Cr, Zr, Nb, Ta, V and Hf, or an alloy thereof.

The film thickness of the first base layer 11A is preferably 3 to 200 nm. This is a thickness required to obtain sufficient adhesion strength, and a thickness that can reduce an increase in surface roughness due to crystal growth in the film.

For the first surface layer 11C, it is preferable to use a material capable of forming a good bond even at a low temperature. In this sense, the first surface layer functions as a bonding layer, and the material constituting the first surface layer is a bonding material. The first surface layer 11C can be made of, for example, at least one metal of Au, Ag, Cu, Sn, Pb, In and Zn, or an alloy thereof.

The film thickness of the first surface layer 11C is preferably 3 to 100 nm. This makes it possible to obtain sufficient bonding strength and reduce the increase in surface roughness due to crystal growth in the film.

The first intermediate layer 11B contains a metal element (second metal element) having a lower thermal diffusion mobility than the metal element (first metal element) that can constitute the getter material. According to this configuration, it is possible to effectively suppress the thermal diffusion of the first metal element to the surface at the time of degassing. In this sense, the first intermediate layer functions as a diffusion barrier layer, and the material constituting the first intermediate layer is a diffusion barrier material. The second metal element preferably contains one metal of Pt, Co, Ru, Ta and W, or an alloy thereof.

The first intermediate layer 11B may consist of one metal of Pt, Co, Ru and W, or an alloy thereof, or at least one of _{TiN, TaN, WN or In 2} O _3. can.

The film thickness of the first intermediate layer 11B is preferably 5 to 20 nm. This suppresses the thermal diffusion of atoms in the first surface layer 11C during the degassing treatment, and is an effective film thickness for the atoms in the first surface layer 11C to reach the surface by thermal diffusion in the activation annealing after bonding. Is.

The first intermediate layer 11B as a diffusion barrier layer may or may not be essential depending on the combination of the first base layer and the first surface layer.

In this example, a laminated film (first laminated film) of the first base layer 11A, the first intermediate layer 11B, and the first surface layer 11C was formed, but two layers of the first base layer 11A and the first surface layer 11C were formed. It may be a laminated film (first laminated film).

In the above example, the laminated film was formed on the entire surface 10Aa of the recess 10A, but after that, the laminated film of the other portion was formed by a known method so that the laminated film remains on a part of the surface 10Aa of the recess 10A. It may be removed. As a method of removing, for example, dry etching can be used. Further, the portion of the surface 10Aa of the recess 10A on which the laminated film is to be formed may be determined in advance, and the laminated film may be formed only on that portion by a known method.

A laminated film (second laminated film) 21 is formed on the surface 20a of the second substrate 20 on the closed space side. Like the laminated film 11, the laminated film 21 may have three layers, a second base layer, a first intermediate layer, and a second surface layer (not shown). In this case, the second base layer, the first intermediate layer, and the second surface layer may be the same as or different from the first base layer 11A, the first intermediate layer 11B, and the first surface layer 11C, respectively. Further, the second base layer, the first intermediate layer and the second surface layer may be selected from the above-mentioned materials for the first base layer 11A, the first intermediate layer 11B and the first surface layer 11C, respectively, or other materials. The material may be selected.

The device D may be arranged in a closed space before or at this stage of the film forming process, or may be manufactured in the closed space by using a known technique.

(Degassing process)
The first substrate 10 on which the first laminated film 11 is formed and the second substrate 20 on which the second laminated film 21 is formed are heated at a first temperature in a vacuum or under reduced pressure for degassing treatment. (See FIG. 3 (c)).

The degassing treatment may be performed simultaneously on the first substrate 10 and the second substrate 20 in the same vacuum chamber, or may be performed separately.

The first temperature at which the degassing treatment is performed can be, for example, a temperature in the range of 100 to 400 ° C. The degree of vacuum for degassing can be, for example, a degree of vacuum within the range of ^{1 × 10 -4 to 10 Pa.} The time for performing the degassing treatment can be, for example, a time within the range of 5 to 30 minutes.

(Joining process)
The first surface layer 11C of the first laminated film 11 of the degassed first substrate 10 and the second surface layer of the second laminated film 21 of the second substrate 20 are joined together (FIG. 3 (d)). reference).

As a joining method, a known method can be used. In the case of vacuum bonding, for example, ^{after degassing at 200 ° C. for 10 minutes in a vacuum of 3 × 10 -3} Pa, the surface layers are bonded to each other in a vacuum while maintaining 200 ° C. Can be done.

(Activation process)
A first substrate 10 and a second substrate 20 that have been joined are heated at a second temperature to form a getter material that constitutes the base layer 11C of the first laminated film 11 of the first substrate 10. The metal element of No. 1 is thermally diffused on the surface to activate it as a getter layer (see FIG. 3 (e)). By performing this step, the first metal element that can form the getter material that constitutes the base layer 11C of the first laminated film 11 can be thermally diffused to the surface, and the recess 10A of the first substrate 10 can be thermally diffused. The portion formed on the surface 10Aa functions as a getter layer. Then, the residual gas in the closed space S can be chemically adsorbed on the surface of the getter layer. For example, when the first metal element is Ti, titanium oxide is formed on the surface of the getter layer.

The second temperature at which the activation step is performed is higher than the temperature at which the degassing step is performed, and can be, for example, a temperature within the range of 350 to 600 ° C.
The time for performing the activation step can be, for example, a time within the range of 30 to 240 minutes.

A second substrate having a recess may be used. In this case, a getter layer may be formed in the recess of the second substrate by the same method as described above.

(1) Experiment on Examination of Appropriate Film Thickness of Diffusion Barrier Layer In the following examples, a laminated film in which a Ti layer / Pt layer / Au layer (this is a Ti layer, a Pt layer, and an Au layer formed in this order from the substrate side). The same applies to the following), so that the Pt layer, which is a diffusion barrier layer, is indispensable. Therefore, the appropriate film thickness was first examined. Sample 1 in which a Ti layer (40 nm) and a Pt layer (2.5 nm) are formed by sputtering on a silicon wafer having a thermal oxide film formed on the surface (hereinafter, may be referred to as a thermal oxide Si substrate), and , Ti layer (40 nm) and Pt layer (5 nm) were formed into a film, and Sample 2 was prepared. Samples 1 and 2 were degassed at 200 ° C., and XPS measurement was performed on the surface of the film.

FIG. 4 shows each XPS spectrum. (A) is for sample 1 and (b) is for sample 2. In sample 1, _{a peak indicating TiO 2} appears around 458 eV, but in sample 2, _{a peak indicating TiO 2} does not appear. This is because when the thickness of the Pt film is 2.5 nm by degassing at 200 ° C., the Ti atoms reach the surface due to thermal diffusion, whereas when the thickness of the Pt film is 5 nm. Shows that the surface reach due to thermal diffusion of Ti atoms is prevented.

(2) Example 1
As shown in FIG. 5, a Ti layer (40 nm), a Pt layer (5 nm), and Au (3 nm) are sequentially applied to each of a thermally oxidized Si substrate having a recess and a flat thermally oxidized Si substrate having no recess. The film was formed to prepare two thermally oxidized Si substrates having a laminated film for bonding (see FIG. 5 (a)). Both of the prepared substrates were degassed at 200 ° C. and then vacuum-sealed to form a sealed structure having a cavity (sealed space) (see FIG. 5 (b)). Further, the sealed structure was activated and annealed in the air at 450 ° C. for 3 hours (see FIG. 5 (c)).

(Tensile test result)
The sealed structure after the activation step was diced and a tensile test (tensile load: 23 MPa) was performed. From the observation of the fractured surface by the tensile test, it was found that the Pt layer hindered the thermal diffusion of Ti atoms and the Au atoms were bonded well to each other. Further, since the silicon oxide film was visible on the fracture surface, it was found that the silicon oxide film was _{peeled off not from the bonding interface between the two substrates but at the interface (SiO 2} / Ti) between the substrate and the bonded laminated film.

(Elemental analysis in the depth direction)
FIG. 6 shows the results of elemental analysis by XPS (X-ray electron spectroscopy) in the depth direction of the getter layer formed on the inner wall of the recess. Further, FIG. 7 shows the XPS spectrum of the Ti2p region in the depth direction. Etching in the depth direction _{was performed with respect to SiO 2 at} an etching rate of about 10 nm per 100 seconds. FIG. 8 shows a transmission electron microscope (TEM image). FIG. 9 shows the results of elemental analysis mapping.

No Ti or Pt was detected on the surface before activation annealing.

Although Ti was not present on the surface before the activation annealing, it was found from FIGS. 6 and 8 that Ti was present. Furthermore, from FIG. 7, it was found that the Ti present on the surface exists not as a metallic Ti but as a Ti compound.

From FIGS. 6, 8 and 9, it was found that Au was present near the surface and Pt was directly below Au.

In the case of a sealed structure having a laminated film of Ti layer (40 nm) / Pt layer (5 nm) / Au layer (12 nm) before the activation step, and Ti layer (40 nm) / Pt layer (20 nm) / It was confirmed that the sealed structure provided with the laminated film of the Au layer (3 nm) also had a good gas gettering function.

(3) Example 2
In Example 2, when a large amount of O ₂ is present in the closed space after the joining step, how the “ti layer / Pt layer / Au layer laminated film” functions as a getter layer and changes due to activation annealing. In order to investigate whether or not the laminated film of the Ti layer / Pt layer / Au layer formed on the thermally oxidized Si substrate was exposed to the atmosphere, activation annealing was performed at 450 ° C. for 3 hours.

FIG. 10 shows the results of elemental analysis by XPS (X-ray electron spectroscopy) in the depth direction of the getter layer formed on the inner wall of the recess. Etching in the depth direction _{was performed with respect to SiO 2 at} an etching rate of about 10 nm per 100 seconds.

According to Example 2, it was found that more oxygen was present near the surface and in the metal film than in Example 1, and Ti was present at a ratio close to the atomic ratio of _{TiO 2 depending on the amount of oxygen.} As a result, it can be seen that the Ti atom moves to the surface and becomes _{TiO 2 and exerts the function of adsorbing O 2 in the atmosphere.} Further, as compared with Example 1, Au is reduced in the vicinity of the surface, Pt is arranged at a position deep to the interface between the metal layer and the substrate, and it can be seen that Ti is present in the entire area.

10 First substrate 10A Recessed portion 11A First base layer 11B First intermediate layer 11C First surface layer 20 Second substrate 30 Joint 40 Getter layer 100 Sealed structure S Sealed space

Claims (14)

A sealed structure having a closed space
A first substrate and a second substrate having recesses on at least one side,
A joint portion arranged so as to surround the recess and joining the first substrate and the second substrate,
A getter layer formed on a part of the surface of the first substrate and the second substrate that defines the enclosed space and absorbs gas in the enclosed space is provided.
The joint contains a first metallic element that can constitute a getter material and contains the first metal element.
The getter layer is a sealing structure containing the first metal element on the surface thereof. The sealing structure according to claim 1, wherein the first metal element contains one of Ti, Cr, Zr, Nb and Ta. The sealing structure according to claim 1 or 2, wherein the getter layer and the joint include a second metal element having a lower thermal diffusion mobility than the first metal element. The sealing structure according to claim 3, wherein the second metal element contains one of Pt, Co, Ru and W. The sealing structure according to any one of claims 1 to 4, wherein the getter layer is formed on the entire inner surface of the recess. A first substrate having a recess, a second substrate, a joint portion arranged so as to surround the recess and joining the first substrate and the second substrate, and a sealed space are defined. A method for manufacturing a sealed structure including a getter layer formed on a part of the surface of the first substrate among the first substrate and the second substrate and absorbing gas in the enclosed space. And
A step of forming a first laminated film by forming a first base layer and a first surface layer in this order on a surface on which at least a joint portion and a getter layer of the first substrate are formed.
A step of forming a second laminated film by forming a second base layer and a second surface layer on the surface of the second substrate in this order.
The first substrate on which the first laminated film is formed and the second substrate on which the second laminated film is formed are heated at a first temperature in a vacuum or under reduced pressure for degassing treatment. And the steps to do
A step of joining the first surface layer of the degassed first substrate and the second surface layer of the second substrate together.
A first metal that can form a getter material that heats the joined first substrate and the second substrate at a second temperature to form the first base layer of the first laminated film. The step of activating the element as a getter layer by thermally diffusing it on the surface,
A method for manufacturing a sealed structure, including. The method for manufacturing a sealing structure according to claim 6, wherein a substrate having a recess is used as the second substrate. The method for manufacturing a sealing structure according to claim 7, wherein a getter layer is also formed on the surface of the recess of the second substrate. The method for producing a sealing structure according to any one of claims 6 to 8, wherein the first base layer contains one metal of Ti, Cr, Zr, Nb and Ta or an alloy thereof. .. The step of forming the first laminated film further includes a step of forming an intermediate layer between the first base layer and the first surface layer to prevent the diffusion of the metal material of the first base layer. The method for producing a sealed structure according to any one of 6 to 9. The method for producing a sealed structure according to claim 10, wherein the intermediate layer contains one metal of Pt, Co, Ru and W or an alloy thereof. The method for producing a sealed structure according to claim 10 or 11, wherein the intermediate layer has a film thickness set in the range of 5 nm to 20 nm. The method for manufacturing a sealing structure according to any one of claims 6 to 12, wherein the second temperature is set higher than the first temperature. The method for producing a sealed structure according to claim 13, wherein the first temperature is selected from the range of 100 ° C. to 400 ° C., and the second temperature is selected from the range of 350 ° C. to 600 ° C.

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