JP2012020894A - Glass for anodic bonding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass which can be anodically bonded to a silicon wafer and the like at a low temperature and is suitable for fabricating MEMS (microelectronic mechanical system) and the like, and to provide a glass which can be anodically bonded more preferably at a low temperature and a low voltage.SOLUTION: The glass for anodic bonding contains, in mol% based on oxides, 0.1-20% NaO and 0.1-50% PO. The glass for anodic bonding more preferably contains, in mol% based on oxides, 30-90% SiO, 0-50% BOand 0-50% AlO.

Description

  The present invention relates to a glass useful for anodic bonding with a semiconductor such as silicon or a metal used for a microelectromechanical element or the like.

  Anodic bonding is a method of bonding a silicon wafer and glass in order to protect the inside from external factors in a microelectromechanical element in which a sensor or actuator (mechanical drive mechanism) and an integrated circuit that drives the sensor are mixed. It is used as a method of bonding various substrates and a glass pedestal in a manufacturing process of a micro electro mechanical element, or a method of bonding a mask substrate such as a silicon wafer and a glass support member.

Anodic bonding is a technique in which a silicon wafer and glass are generally heated to 300 ° C. to 600 ° C. and a voltage is applied to bond the two. Anodic bonding is mainly used as a sealing technology for MEMS (microelectronic mechanical system) from the viewpoint that sealing with glass provides high airtightness and strong bonding by covalent bonding.
In recent years, in consumer devices equipped with a MEMS sensor, downsizing of the device is a market trend and a demand. Therefore, in order to reduce the size of the device, there is an idea of downsizing or integrating the MEMS. There is also an idea that a composite device is formed by mixing an integrated circuit and a MEMS device. However, in current anodic bonding, especially in hermetic sealing applications, the problem that the MEMS element is damaged by heating during anodic bonding, and the bonding site of the MEMS element etc. performed before the anodic bonding process can be used for heating during anodic bonding. Since it must be able to withstand, there are problems such as a limited bonding method. Therefore, it is difficult to reduce the size and integration of the MEMS element and to combine the integrated circuit and the MEMS element. An anodic bonding method is also used for solar power generation elements, and bonding at 250 ° C. or lower is particularly required for thin-film solar power generation elements. Therefore, it is expected to lower the temperature of anodic bonding.
On the other hand, there is a market demand for cost reduction of devices. In manufacturing the MEMS constituting the device, it is necessary to make the equipment capable of withstanding the temperature of the conventional anodic bonding, and there is a problem that the manufacturing cost increases. Therefore, it is expected to lower the temperature of anodic bonding.
In order to perform anodic bonding at a low temperature, it is effective to apply a high voltage. However, since the high voltage damages the MEMS element, it is difficult to perform anodic bonding at a low temperature.

Patent Document 1 discloses anodic bonding glass, but requires a heating temperature of 240 ° C. at the minimum.
JP 2001-72433 A

  An object of the present invention is to provide a glass capable of anodic bonding at a low temperature. More preferably, it is to provide a glass capable of anodic bonding at a low temperature and a low voltage, and in addition, to provide a glass with little precipitation of alkali components on the substrate surface.

  As a result of intensive studies in view of the above problems, the present inventor has found that the above problems can be solved by defining the content range of specific components, and has completed the present invention. The main configuration is as follows.

(Configuration 1)
A glass for anodic bonding containing 0.1% to 20% of Na ₂ O and 0.1% to 50% of P ₂ O _{5 in} terms of mol% based on oxide.
(Configuration 2)
In mole percent on oxide basis,
30% to 90% of _SiO 2,
0-50% B ₂ O ₃ ,
0% to 50% of _Al 2 _{O 3}
The glass for anodic bonding according to Configuration 1 containing each of the components.
(Configuration 3)
It contains one or more components selected from MgO, ZnO, BeO, CaO, SrO, BaO, ZrO ₂ , TiO ₂ , MnO, and Fe ₂ O _{3 in} terms of oxide, and the total amount of these components is oxide The glass for anodic bonding according to Configuration 1 or 2, which is 30% or less in terms of mol% of the reference.
(Configuration 4)
In mole percent on oxide basis,
0-20% MgO,
0% to 20% ZnO
The glass for anodic bonding according to any one of constitutions 1 to 3 containing each of the components.
(Configuration 5)
5. The composition according to any one of the constitutions 1 to 4, wherein the total amount of one or more components selected from Li ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O is 10% or less in terms of mol% based on the oxide. Anodic bonding glass.
(Configuration 7)
The glass for anodic bonding according to any one of Structures 1 to 6, wherein the total amount of at least one component selected from BeO, CaO, SrO, and BaO is 10% or less in terms of mol% based on oxide.
(Configuration 8)
For anodic bonding according to any one of Structures 1 to 7, wherein the total amount of at least one component selected from ZrO ₂ , TiO ₂ , MnO, and Fe ₂ O ₃ is 20% or less in terms of mol% based on oxide. Glass.
(Configuration 9)
The glass for anodic bonding according to any one of Structures 1 to 8, wherein an average linear expansion coefficient at 30 ° C. to 400 ° C. is 25 × 10 ⁻⁷ / ° C. to 70 × 10 ⁻⁷ / ° C.

  In the present invention, glass is a concept including both amorphous glass and crystallized glass.

  According to the glass of the present invention, it is possible to provide a glass capable of anodic bonding at a low temperature of, for example, 200 ° C. or lower. By performing anodic bonding using this glass, thermal damage of the MEMS element can be reduced. In addition, there are more options for bonding methods such as MEMS elements. Since it is not necessary to give the manufacturing equipment high heat resistance, the MEMS device can be manufactured at low cost.

It is explanatory drawing explaining the outline | summary of an anodic bonding test.

Each component which comprises the glass of this invention is demonstrated. Unless otherwise specified, in the present specification, each component is expressed in terms of mol% based on oxide.
Here, the “oxide standard” means that oxides, nitrates, carbonates, etc. used as raw materials of the constituent components of the glass of the present invention are all decomposed and changed into oxides when melted. This is a method of expressing the composition of each component contained, and the amount of each component contained in the glass is described with the total number of moles of the resulting oxide as 100 mol%.

The glass of the present invention can be bonded at a low temperature by containing each component of 0.1% to 20% Na ₂ O and 0.1% to 50% P ₂ O ₅ in mol% based on oxide. An anodic bonding glass can be provided.

The Na ₂ O component behaves as a mobile ion during anodic bonding, and is a component that enables glass to be used for anodic bonding, and is an essential component. The greater the content of the Na ₂ O component, the greater the number of mobile ions and the stronger the electrostatic force between silicon and glass, so that anodic bonding at a temperature lower than 300 ° C. is possible. Since the Na 2 _O content of component becomes difficult to anodic bonding at a low temperature than would 300 ° C. is less less mobile ions than 0.1%, the lower limit of the Na 2 _O content component 0. 1% is preferred. In order to make it easier to obtain the above effect, the lower limit of the Na ₂ O component is more preferably 1%, and most preferably 2%.
Further, the average linear expansion coefficient of the glass and the Na 2 _O content component is greater than 20% becomes larger than a desired value, the glass resulting in devitrification. Therefore, the content of the Na ₂ O component is preferably 20% or less, more preferably 15% or less, and most preferably 12% or less.

The P ₂ O ₅ component is a component that forms a glass skeleton, and when the P ₂ O ₅ component is contained, the P ₂ O ₅ component is easily polarized when a voltage is applied. Therefore, mobile ions are easily conducted, and anodic bonding at a temperature lower than 300 ° C. is possible, which is an essential component.
If the content of the P ₂ O ₅ component is less than 0.1%, polarization is difficult, and anodic bonding at a temperature lower than 300 ° C. becomes difficult. Therefore, the lower limit of the content of the P ₂ O ₅ component is 0.1 % Is preferred. In order to make the above effect easier to obtain, the lower limit of the P ₂ O ₅ component is more preferably 1%, and most preferably 2%.
On the other hand, if it exceeds 50%, the average linear expansion coefficient of the glass becomes larger than a desired value, and the glass is devitrified.
Therefore, the content of the P ₂ O ₅ component is preferably 50% or less, more preferably 20% or less, and most preferably 10% or less.

  Thus, by containing a specific amount of the specific component, it is possible to provide a chemically stable glass for anodic bonding that can be bonded at a low temperature and has little precipitation of alkali components.

The SiO ₂ component is a component that forms a glass skeleton, and has an effect of reducing the average linear expansion coefficient and obtaining an average linear expansion coefficient equivalent to that of silicon. When the content of the SiO ₂ component is less than 30%, the average linear expansion coefficient becomes larger than a desired value and the chemical durability tends to deteriorate. Accordingly, the content of the SiO ₂ component is preferably 30% or more, more preferably 50% or more, and most preferably 55% or more.
Further, the content of SiO ₂ component is often the meltability of the glass deteriorates than 90%. Therefore, the content of the SiO ₂ component is preferably 90% or less, more preferably 72% or less, and most preferably 68%.

The B ₂ O ₃ component is a component that can form a glass skeleton similarly to the SiO ₂ component, and has the effect of improving the meltability and approximating the curve of the average linear expansion coefficient to the curve of the average linear expansion coefficient of silicon. , An optional component. However, when the content of this component exceeds 50%, chemical durability is deteriorated and devitrification easily occurs. Therefore, the upper limit of the content of the B ₂ O ₃ component is preferably 50% or less, more preferably 20% or less, and most preferably 15% or less.

The Al ₂ O ₃ component is an effective component that can form a glass skeleton, stabilizes the glass, and approximates the average linear expansion coefficient curve to the average linear expansion coefficient curve of silicon. It can be included. However, if the amount of the Al ₂ O ₃ component is more than 50%, the glass is devitrified and is difficult to polarize. Therefore, the content of the Al ₂ O ₃ component is preferably 50% or less, more preferably 30% or less, and most preferably 25% or less.

Further, in order to form a stable glass skeleton of SiO ₂ component, P ₂ O ₅ component, B ₂ O ₃ component, and Al ₂ O ₃ component, the total amount of these components is preferably 50% or more, It is preferably 60% or more, and most preferably 65% or more. The total amount of these components is preferably 99.9% or less.

The ratio of the amount of the SiO ₂ component to the amount of the P ₂ O ₅ component contributes to the improvement of the polarizability at the time of applied voltage and the chemical durability of the glass, and the SiO ₂ / expressed in mol% based on the oxide. The ratio value of P ₂ O ₅ is preferably 1 or more and 100 or less, more preferably 2 or more and 50 or less, and most preferably 5 or more and 30 or less. If the ratio is less than 1, the chemical durability of the glass may be reduced. On the other hand, if the ratio is more than 100, the glass may be difficult to polarize when applied.

The glass for anodic bonding of the present invention contains one or more components selected from MgO, ZnO, BeO, CaO, SrO, BaO, ZrO ₂ , TiO ₂ , MnO, and Fe ₂ O ₃ in oxide representation. The total amount of these components is preferably 30% or less in terms of mol% based on the oxide. These components are components that contribute to the stabilization of the glass. By setting the total amount of these components to 30% or less, devitrification of the glass can be effectively suppressed. In order to make this effect easier to obtain, the total amount is more preferably 20% or less, and most preferably 15% or less.

  Further, in oxide display, one or more components selected from BeO, CaO, SrO, and BaO are effective components for improving the meltability. When the total amount of these components exceeds 10%, the average linear expansion coefficient increases and the volume resistivity increases, and anodic bonding at a temperature lower than 300 ° C. tends to be difficult. Therefore, the total amount of the components is preferably 10% or less, more preferably 5% or less, and most preferably 2% or less.

Further, in oxide display, the glass is stabilized by suppressing the total amount of one or more components selected from ZrO ₂ , TiO ₂ , MnO, and Fe ₂ O ₃ to 20% or less, and devitrification of the glass is suppressed. The effect is easy to obtain. Therefore, the total amount of the components is preferably 20% or less, more preferably 10% or less, and most preferably 5% or less.

  The MgO component is a component that stabilizes the glass and improves the meltability, and can be optionally contained. However, if the content is more than 20%, the average linear expansion coefficient becomes larger than a desired value and the glass tends to devitrify. Therefore, the content of the MgO component is preferably 20% or less, more preferably 12% or less, and most preferably 8% or less.

  The ZnO component is a component having a large effect of improving the meltability and chemical durability and reducing the average linear expansion coefficient, and can be optionally contained. However, if the content is more than 20%, the glass tends to devitrify. Therefore, the content of the ZnO component is preferably 20% or less, more preferably 15% or less, and most preferably 10% or less.

The BeO component is a component that can be optionally added to easily lower the melting temperature. However, if the content is large, mobile ions are difficult to conduct and the average linear expansion coefficient becomes large. Therefore, the upper limit of the content is preferably 10% or less, more preferably 5% or less, and most preferably 3% or less. It is.

  The CaO component is a component that can be optionally added to easily lower the melting temperature. However, if the content is large, mobile ions are difficult to conduct and devitrification at the time of hot molding increases. Therefore, the upper limit of the content is preferably 10% or less, more preferably 5% or less, most preferably. Is 3% or less.

  The SrO component is a component that can be optionally added to easily lower the melting temperature. However, if the addition amount is large, mobile ions are difficult to conduct and the average linear expansion coefficient tends to increase, so the upper limit of the content is preferably 10% or less, more preferably 5% or less, and most preferably 3%. It is as follows.

  The BaO component is a component that can be optionally added to easily suppress the phase separation of the glass and to lower the melting temperature. However, if the addition amount is large, mobile ions are difficult to conduct and the average linear expansion coefficient tends to increase, so the upper limit of the content is preferably 10% or less, more preferably 5% or less, and most preferably 3%. It is as follows.

Each component of Li ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O is a component that improves the meltability, and can be optionally contained. However, if the total amount of these components is more than 10%, the average linear expansion coefficient of the glass becomes larger than a desired value, and mobile ions are difficult to conduct, and anodic bonding at a temperature lower than 300 ° C. It becomes difficult. Therefore, the total amount of these components is preferably 10% or less, more preferably 1% or less.
_{Further, Li 2 O, K 2 O} , Rb 2 O, since each component of Cs ₂ O is a component that inhibits the ionic conductivity of the movable ions, these components is most preferably not substantially contained.

Each component of Li ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O is a component that facilitates lowering the melting temperature. Each of these components can be arbitrarily added within the range of the above total amount. However, if the content of each component is large, it becomes difficult for mobile ions to conduct and the average linear expansion coefficient tends to increase, resulting in poor chemical durability. Therefore, the content of each component is preferably 10%, respectively. Hereinafter, it is more preferably 3% or less, and most preferably not contained.

ZrO ₂ component, TiO ₂ component, MnO component and Fe ₂ O ₃ component are components that stabilize glass, but can be optionally contained, but insoluble matter is generated when the content of each of these components exceeds 20%. Therefore, the upper limit of each content of the ZrO ₂ component and the TiO ₂ component is preferably 20% or less, more preferably 10% or less, and most preferably 5% or less.

As ₂ O ₃ component and Sb ₂ O ₃ component are components that can be optionally added as a glass refining agent. However, since the clarification effect does not increase even when added in a large amount, the content of As ₂ O ₃ component and / or Sb ₂ O ₃ component is limited to 5%, preferably 3% or less, most preferably 1% or less. .

However, the As ₂ O ₃ component and the Sb ₂ O ₃ component have recently tended to be refrained from use in consideration of the influence on the human body and the environment. In this respect, it is preferable that these components are not contained as much as possible. In the glass of the present invention, a CeO ₂ component and / or a SnO ₂ component can be used as an alternative to the fining agent. Even if these components are added in a large amount as in the case of the As ₂ O ₃ component and the Sb ₂ O ₃ component, the clarification effect does not increase. Therefore, the content of the CeO ₂ component and / or the SnO ₂ component is preferably limited to 5%. Is 4% or less, most preferably 3% or less.

  Since the PbO component requires measures for environmental measures when manufacturing, processing, and discarding the glass, and costs are required for this, PbO should not be contained in the glass of the present invention.

The average linear expansion coefficient of the glass of the present invention is in the range of 25 × 10 ⁻⁷ ° C. ⁻¹ to 70 × 10 ⁻⁷ ° C. ^{−1 in} the range of 30 ° C. to 400 ° C. In a more preferred embodiment, an average linear expansion coefficient in the range of 27 × 10 ⁻⁷ ° C. ^{−1 to} 62 × 10 ⁻⁷ ° C. ⁻¹ can be obtained in the range of 30 ° C. to 400 ° C.

As a method for producing the glass of the present invention, a known melting method can be used. That is, silica sand, boric acid, aluminum oxide, aluminum metaphosphate, lithium carbonate, sodium carbonate, potassium carbonate, cesium oxide, magnesium oxide, calcium oxide, nitric acid so that the glass of the present invention has a composition expressed on an oxide basis. Fill a crucible made of quartz, alumina, platinum or the like with a glass raw material made of strontium, barium nitrate, zinc oxide, zirconium oxide, titanium oxide, manganese oxide, iron oxide, arsenous acid, antimony pentoxide, tin oxide, cerium oxide or the like. . And it heat-melts in melting furnaces, such as an electric furnace and a gas furnace. In the glass of the present invention, the melting temperature of the glass raw material is 1600 ° C. or lower, and the temperature at the time of heating and melting in the melting furnace is 1450 ° C. to 1600 ° C. it can.
After melting, clarification and stirring are performed as necessary to homogenize the glass, and then the molten glass is poured into a mold and rapidly cooled to form and slowly cool in a slow cooling furnace.

The glass for anodic bonding of the present invention can obtain an average linear expansion coefficient approximate to that of silicon even in a glass state, but by heat treating the obtained glass to precipitate crystals having a negative average linear expansion coefficient, It is also possible to further adjust the average linear expansion coefficient of the entire glass. In this case, the heat treatment is performed at 500 ° C. to 900 ° C. for 1 hour to 30 hours to perform nucleation, and then heat treatment is performed at 600 ° C. to 1000 ° C. for 1 hour to 30 hours to perform crystal growth. After the heat treatment for crystallization, the temperature is gradually lowered and gradually cooled. The crystals to be precipitated are preferably mullite, cordierite, nepheline, etc. in that they have a small average linear expansion coefficient. In order to more closely approximate the thermal expansion with the silicon wafer, the crystallinity of the crystallized glass is preferably 50% or less, and most preferably 47% or less in terms of mol%. The average particle size of the precipitated crystals is preferably in the range of 50 nm to 200 nm. Inclusion of a large amount of alkali metal oxide increases mobile ions and contributes to lowering the anodic bonding temperature, but alkali metal oxide is a component that increases thermal expansion. Therefore, if the average linear expansion coefficient of the glass is lowered by reducing the content of alkali metal oxide, and the thermal expansion of the silicon wafer and the glass for anodic bonding is approximated, it is contrary to the low temperature of the anodic bonding. It becomes. However, crystallized glass has a low thermal expansion as a whole by precipitating crystals with a small average linear expansion coefficient while increasing the alkali metal oxide content in the glass phase and lowering the temperature during anodic bonding. Can be obtained.
However, because the crystallized glass has fine unevenness on the surface after polishing due to the difference in hardness between the crystal phase and the glass phase, the strength after anodic bonding may not be sufficiently obtained due to the unevenness. The glass for anodic bonding is more preferably glass that is not crystallized. In addition, when glass that has not been crystallized is used for anodic bonding glass, a heat treatment step for precipitating crystals is not necessary, and the manufacturing cost can be reduced.

  It is more preferable that the glass after the slow cooling is cut and ground as necessary to obtain a desired shape and the bonding surface is polished. In this case, the surface property of the joint surface is preferably 10.0 nm or less, and most preferably 5.0 nm or less in terms of arithmetic average roughness Ra defined in JIS B0601.

  In addition, the glass taken out from the slow cooling furnace is processed into a powder form, mixed with a binder, a solvent and the like to form a slurry, and then a green sheet is formed by a doctor blade method, etc., and the green sheet is dried and sintered to obtain a plate-like anode. It is also possible to produce a joining member. It is also possible to adjust the physical properties such as the average linear expansion coefficient and mechanical strength by mixing ceramic powder such as alumina and cordierite into the slurry.

  About the glass for anodic bonding of this invention, the anodic bonding test with a silicon wafer was implemented.

[Production of glass]
Examples of the present invention will be described. Silica sand, boric acid, aluminum oxide, aluminum metaphosphate, lithium carbonate, sodium carbonate, potassium carbonate, cesium oxide, magnesium oxide so that the glass has a composition ratio shown in Tables 1 and 2 expressed in mol% of oxide basis A glass raw material batch composed of calcium oxide, strontium nitrate, barium nitrate, zinc oxide, zirconium oxide, titanium oxide, manganese oxide, iron oxide, arsenous acid, antimony pentoxide, tin oxide, cerium oxide and the like was prepared. The batch was filled in an alumina or platinum crucible and heated and melted at a temperature of 1400 to 1550 ° C. for 6 to 24 hours in an electric furnace. The molten glass was molded into a plate shape and slowly cooled. According to JOGIS (Japan Optical Glass Industry Association Standard) 16-2003 “Measuring Method of Average Linear Expansion Coefficient of Optical Glass Near Room Temperature”, the temperature range was changed from 30 ° C. to 400 ° C. The coefficient was measured. The measured average linear expansion coefficient (α) values are shown in Tables 1-2.

[Glass processing]
To make a glass sample with a shape suitable for the joining test, the produced plate glass is hollowed into a cylindrical shape of the desired size, cut into a disk-shaped substrate of the desired thickness by slicing, and polished with a double-side precision polishing machine Carried out. Thereafter, the arithmetic average roughness Ra of the glass sample surface was measured by New View made by Zygo. The shape of the glass sample after processing and the arithmetic average roughness Ra are described in Tables 1-2.

[Joint test]
An anodic bonding test was conducted between the silicon wafer and the produced glass sample.
The silicon wafer is P type doped with boron manufactured by Ferrotec Silicon Co., Ltd., the silicon purity is about 99.999996%, the orientation is (100) ± 1.0 °, the specific resistance is 1 to 20 Ω · cm, and the diameter is 76. A thickness of 0.5 mm and a thickness of 0.8 mm was used.
For anodic bonding, AB40 custom-made product (owned by Kanagawa Prefectural Industrial Technology Center) manufactured by Ayumi Industry Co., Ltd. is used. As shown in Fig. 1, the silicon wafer side is positive, the glass side is negative, and the temperature is 200 ° C and the DC voltage is 800V. It was performed by applying for 10 minutes.
The maximum current value (mA) at this time is shown in Tables 1-2.

After the joining test, the joining was evaluated. In the evaluation, a value obtained by dividing the area of the glass sample bonded to the silicon wafer by the area of the entire one surface of the glass sample was evaluated as a bonding ratio (%). The region that was darkly discolored after the bonding test was defined as the region bonded to the silicon wafer.

  As shown in Tables 1 and 2, the glass for anodic bonding according to the present invention had a bonding area of 74% to 100%, and showed good bondability even at a low temperature of 200 ° C.

  Moreover, about the glass sample of the composition of Example 1, the joining test was done on the conditions similar to the above except having changed the DC voltage at the time of joining into 600V. As a result, the joining ratio was 85%, and good joining results were obtained.

1 plus electrode 2 heater 3 minus electrode / heater 4 silicon wafer 5 glass sample

Claims (8)

A glass for anodic bonding containing 0.1% to 20% of Na ₂ O and 0.1% to 50% of P ₂ O _{5 in} terms of mol% based on oxide. In mole percent on oxide basis,
30% to 90% of _SiO 2,
0-50% B ₂ O ₃ ,
0% to 50% of _Al 2 _{O 3}
The glass for anodic bonding according to claim 1 containing each of the components. It contains one or more components selected from MgO, ZnO, BeO, CaO, SrO, BaO, ZrO ₂ , TiO ₂ , MnO, and Fe ₂ O _{3 in} terms of oxide, and the total amount of these components is oxide The glass for anodic bonding according to claim 1, which is 30% or less in terms of mol% of the reference. In mole percent on oxide basis,
0-20% MgO,
0% to 20% ZnO
The glass for anodic bonding according to any one of claims 1 to 3 containing each of the components. 5. The total amount of at least one component selected from Li ₂ O, K ₂ O, Rb ₂ O, and Cs ₂ O is 10% or less in terms of mol% based on oxide. Anodic bonding glass.   The glass for anodic bonding according to any one of claims 1 to 6, wherein the total amount of at least one component selected from BeO, CaO, SrO, and BaO is 10% or less in terms of mol% based on the oxide. 8. The anodic bonding according to claim 1, wherein the total amount of at least one component selected from ZrO ₂ , TiO ₂ , MnO, and Fe ₂ O ₃ is 20% or less in terms of mol% based on oxide. Glass. 9. The glass for anodic bonding according to claim 1, wherein an average linear expansion coefficient at 30 ° C. to 400 ° C. is 25 × 10 ⁻⁷ / ° C. to 70 × 10 ⁻⁷ / ° C. 9.

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