JP2006069863A - Anodic bonding method and anodic bonding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anodic bonding method capable of obtaining a simple and sound bonded part when multilayer bonding a glass substrate and a metal substrate.
An Ag layer 12 is formed in advance on one surface of a glass substrate 11, the Ag layer 12 is connected to the positive electrode side, and a voltage is applied to the glass substrate 11 and the Ag layer 12 so that Ag is contained in the glass substrate 11. The Ag layer 12 is removed from the surface of the glass substrate 11, the silicon substrate 15 is brought into contact with the surface of the glass substrate 11 on which Ag is infiltrated, and the silicon substrate 15 is connected to the positive electrode side. 11 and the silicon substrate 15 are subjected to anodic bonding by applying a voltage.
[Selection] Figure 1

Description

  The present invention relates to an anodic bonding method and an anodic bonding structure.

  Some detectors such as pressure sensors that receive mechanical physical quantities and convert them into electrical signals are manufactured by anodically bonding a glass substrate on which an electrode pattern is formed to a silicon substrate on which a detector is formed. . In anodic bonding, generally, a glass substrate connected to the negative electrode side and a silicon substrate connected to the positive electrode side are brought into contact with each other, and a voltage is applied to both of the glass substrate and the silicon substrate by a voltage application device. It is what is joined.

  FIG. 15 is a schematic diagram showing an outline of a method for anodic bonding between the glass substrate 1 and the silicon substrate 2. Glass substrate 1 is a general purpose glass such as borosilicate glass, and contains alkali metal such as sodium (Na).

FIG. 15A shows a state where the glass substrate 1 and the silicon substrate 2 are simply brought into contact with each other. When the glass substrate 1 and the silicon substrate 2 are brought into contact with each other, a macroscopic gap 3 exists at the molecular level even though they seem to be in close contact with each other. FIG. 15B shows a state where a voltage is just applied with the glass substrate 1 connected to the negative electrode side and the silicon substrate 2 connected to the positive electrode side. When the voltage is applied, Na is ionized to plus (+) and oxygen (O) is minus (−) in the glass substrate 1. Na existing near the interface with the silicon substrate 2 becomes Na ⁺ and begins to move toward the negative electrode connection side of the glass substrate 1.

In the vicinity of the interface between the glass substrate 1 and the silicon substrate 2, O ²⁻ is relatively enriched by the movement of Na ⁺ having a high mobility in the glass, and a negative charge layer is formed. On the other hand, since a positive charge layer is formed in the vicinity of the interface between the silicon substrate 2 and the glass substrate 1, as shown in FIG. 15C, a static charge acting between the negative charge layer and the positive charge layer is formed. Due to the attractive force, the glass substrate 1 and the silicon substrate 2 are brought into close contact with each other at the molecular level, and the gap 3 disappears. At the interface between the glass substrate 1 and the silicon substrate 2, adjacent Si ⁺ and O ²⁻ are bonded to form an anodic oxide (SiO ₂ ) layer 5 as shown in FIG. 1 and the silicon substrate 2 are anodically bonded. At this time, the alkali ion deficient layer 4 is formed in the vicinity of the bonding interface of the glass substrate 1 due to the movement of Na ⁺ .

  In anodic bonding, since it is a heterogeneous bonding between a glass substrate and a silicon substrate, it is difficult to obtain sufficient bonding strength, and it is required to further increase the bonding strength. For example, a silicon oxide film is previously formed on the surface of the glass substrate. It has been proposed to improve the bonding strength by increasing the number of oxygen ions, which are the product of anodic oxide at the bonding interface (see, for example, Patent Document 1).

  However, in anodic bonding, in addition to simply improving the bonding strength as in Patent Document 1, the soundness of the bonded portions in various forms of bonding structures is required. For example, joint soundness in a multi-layer joint structure in which silicon substrates and glass substrates are alternately laminated is required.

  FIG. 16 is a schematic diagram showing an outline of a method for anodic bonding of a silicon substrate and a glass substrate in multiple layers. In the multilayer bonding structure as shown in FIG. 16, after the first anodic bonding is performed by connecting the silicon substrate 2 to the positive electrode side and the glass substrate 1 to the negative electrode side as described above, another silicon substrate 6 is bonded. Then, the glass substrate 1 is brought into contact with the opposite side of the bonded silicon substrate 2, the other silicon substrate 6 is connected to the positive electrode side, the bonded silicon substrate 2 is connected to the negative electrode side, and the second anode Join. Therefore, the direction of the potential applied to the glass substrate 1 is reversed between the first anodic bonding and the second anodic bonding. The application of a voltage so that the direction of the potential is reversed is hereinafter referred to as reverse voltage application.

When a reverse voltage is applied to the glass substrate 1, Na ^+, which is an alkali metal ion, is formed in the vicinity of the anodic oxide layer 5, which is a bonding interface formed on the silicon substrate 2 side that becomes a negative electrode in the second anodic bonding. Accumulate. If this Na ⁺ accumulates at the bonding interface, it not only leaks into the bonding interface and contaminates the silicon substrate 2, but also the accumulated Na ⁺ reduces the bonding strength between the silicon substrate 2 and the glass substrate 1. There is a problem in that peeling of the film is caused and deterioration of water resistance in the joint portion is caused.

  As one method for multi-layer bonding of a silicon substrate and a glass substrate, an anodic bonding method has been proposed in which a glass substrate is bonded to both surfaces of a single silicon substrate (see Patent Document 2). In the technique disclosed in Patent Document 2, first, a first glass substrate is connected to one surface of a silicon substrate, and the silicon substrate is connected to a positive electrode and the first glass substrate is connected to a negative electrode to perform anodic bonding. Thereafter, when the second glass substrate is bonded to the other surface of the silicon substrate, a glass layer is formed on the other surface of the silicon substrate, and aluminum (Al) or titanium is formed on the surface of the second glass substrate facing the silicon substrate. A metal oxide layer of (Ti) is formed, and the second glass substrate side is connected to the positive electrode, and the silicon substrate side is connected to the negative electrode, that is, with a reverse voltage, and anodic bonded. According to the technique of Patent Document 2, although the reverse voltage is present between the silicon substrate and the second glass substrate, the metal layer is the positive electrode side and the glass layer is the negative electrode between the metal oxide layer and the glass layer. Since this is in the normal anodic bonding potential state on the side, a strong bonded portion can be obtained.

  However, in the technique of Patent Document 2, since a glass layer must be formed on a silicon substrate and a metal oxide layer must be formed on a second glass substrate, the number of processes increases and productivity deteriorates. There is. Further, since the glass layer is formed on the silicon substrate by applying water glass, the bonding strength between the silicon substrate and the glass layer is not sufficient, and the metal oxide is formed on the second glass substrate by vapor deposition. However, there is a problem that it cannot be said that the bonding strength is sufficient.

  Thus, there is a demand for an anodic bonding method and a bonding structure that can provide a simple and sound bonded portion in multilayer bonding of a glass substrate and a metal substrate.

JP 2001-274416 A JP 2003-306351 A

  An object of the present invention is to provide an anodic bonding method and an anodic bonding structure capable of easily and obtaining a sound bonded portion when multilayer bonding a glass substrate and a metal substrate or a metal element-containing substrate.

The present invention is an anodic bonding method for bonding a glass substrate and a metal substrate or a metal element-containing substrate,
Forming a movable metal layer comprising a movable metal in a glass substrate in advance on one surface of the glass substrate;
Connecting the movable metal layer to the anode side, applying a voltage to the glass substrate and the movable metal layer, and infiltrating the movable metal into the glass substrate;
Removing the movable metal layer from the surface of the glass substrate;
A metal substrate or a metal element-containing substrate is brought into contact with the surface of the glass substrate on which the movable metal is infiltrated, and the metal substrate or the metal element-containing substrate is connected to the anode side. And applying a voltage to the substrate to bond the glass substrate to the metal substrate or the metal element-containing substrate.

Further, the present invention provides an anodic bonding method for bonding a glass substrate and a metal substrate or a metal element-containing substrate,
Forming a movable metal layer comprising a movable metal in a glass substrate in advance on one surface of the metal substrate or the metal element-containing substrate;
The glass substrate is brought into contact with the surface of the metal substrate or the metal element-containing substrate on which the movable metal layer is formed, the metal substrate or the metal element-containing substrate is connected to the anode side, and the glass substrate and the metal substrate or metal element are connected. And applying a voltage to the contained substrate to join the glass substrate and the metal substrate or the metal element-containing substrate.

  Further, the present invention provides another metal substrate or a metal element-containing substrate in contact with the surface of the glass substrate opposite to the side bonded to the metal substrate or the metal element-containing substrate. A substrate is connected to the positive electrode side, a voltage is applied to another metal substrate or a metal element-containing substrate, a glass substrate, and a metal substrate or a metal element-containing substrate, and another metal substrate or a metal element-containing substrate and a glass substrate The method further includes a step of bonding the metal substrate or the metal element-containing substrate.

  In the present invention, the movable metal is 1 or 2 selected from silver and copper.

In the present invention, the metal substrate is a silicon substrate.
In the present invention, the metal element-containing substrate is a ceramic substrate.

Further, the present invention is an anodic bonding structure in which a glass substrate and a metal substrate or a metal element-containing substrate are bonded,
An anode bonding structure characterized in that a permeation layer of a movable metal element in a glass substrate is provided in the vicinity of an interface on a bonding side of the glass substrate bonded to the metal substrate or the metal element-containing substrate.

  Further, the present invention is characterized in that the movable metal element is 1 or 2 selected from silver and copper.

  According to the present invention, the movable metal is preliminarily permeated into the glass substrate, and the metal substrate or the metal element-containing substrate is brought into contact with the surface of the glass substrate on which the movable metal is impregnated. The element-containing substrate is connected to the positive electrode side, and a voltage is applied to the glass substrate and the metal substrate or the metal element-containing substrate to anodic bond the glass substrate and the metal substrate or the metal element-containing substrate. By performing this anodic bonding, the glass substrate is connected to the positive electrode side and the metal substrate or the metal element-containing substrate is connected to the negative electrode side, for example, when a glass substrate and a metal substrate or a metal element-containing substrate are bonded in multilayer. When a reverse voltage is applied, the permeated mobile metal ions in the glass substrate move and accumulate near the junction interface between the glass substrate and the metal substrate or the metal element-containing substrate, and thus are contained in the glass substrate. Alkali metal ions can be prevented from accumulating and leaking at the bonding interface. Accordingly, the occurrence of contamination, cracking and peeling of the joint portion with alkali metal is prevented, and soundness is ensured.

  Further, according to the present invention, the movable metal layer containing the movable metal in the glass substrate is formed in advance on one surface of the metal substrate or the metal element-containing substrate, and the movable metal layer is formed. The glass substrate is brought into contact with the surface on the side, the metal substrate or the metal element-containing substrate is connected to the positive electrode side, a voltage is applied to the glass substrate and the metal substrate or the metal element-containing substrate, and the glass substrate and the metal substrate Alternatively, the metal element-containing substrate is anodically bonded. According to this anodic bonding, the same effect as that of the above-described invention can be obtained, and the penetration of the movable metal into the glass substrate and the bonding of the metal substrate or the metal element-containing substrate to the glass substrate are simultaneously performed. Since it can be performed, anodic bonding that can ensure a sound joint even when a reverse voltage is applied can be realized more simply.

  According to the invention, the metal substrate or the metal element-containing substrate is anodically bonded to both surfaces of the glass substrate. When a reverse voltage is applied by anodic bonding between another metal substrate or a metal element-containing substrate and a glass substrate, the mobile metal ions in the glass substrate are converted into the first metal substrate or the metal element-containing substrate and the glass. Since accumulation is performed in the vicinity of the anodic bonding interface with the substrate, accumulation of alkali metal ions is prevented and sound multilayer anodic bonding can be realized.

  From the gist of the invention of applying a reverse voltage to a glass substrate and a metal substrate or a metal element-containing substrate to perform multi-layer anodic bonding, deformation of anodic bonding of the glass substrate on both surfaces of the metal substrate or metal element-containing substrate is allowed. Needless to say.

  Moreover, according to this invention, 1 or 2 is selected from silver and copper as a movable metal. Since silver and copper have the same mobility as alkali metal ions in the glass substrate, it is easy to permeate, and the permeated silver or copper ions move while suppressing the movement of alkali metal ions. be able to. Therefore, silver and copper are suitably used for ensuring the soundness of the joint in anodic bonding to which a reverse voltage is applied.

  According to the invention, the metal substrate is a silicon substrate, and the metal element-containing substrate is a ceramic substrate. This realizes multilayer anodic bonding between the glass substrate and the silicon substrate and multilayer anodic bonding between the glass substrate and the ceramic substrate.

  Further, according to the present invention, the anodic bonding structure has a movable metal element in the glass substrate, preferably silver and copper, in the vicinity of the interface on the bonding side of the glass substrate bonded to the metal substrate or the metal element-containing substrate. 1 or 2 osmotic layers selected from Such an anodic bonding structure ensures the soundness of the joint between the glass substrate and the metal substrate or the metal element-containing substrate even when a reverse voltage is applied. A multilayer structure excellent in the quality of the joint with the substrate can be obtained.

  FIG. 1 is a diagram for explaining the outline of the anodic bonding method according to the first embodiment of the present invention. Hereinafter, the anodic bonding method according to the first embodiment will be described with reference to FIG.

  In the step shown in FIG. 1A, a movable metal layer 12 including a movable metal in the glass substrate 11 is formed in advance on one surface of the glass substrate 11. Examples of the glass substrate 11 include borosilicate glass. Here, the mobile metal is a metal whose ion mobility in the glass substrate is substantially the same as that of an alkali metal such as sodium (Na) or lithium (Li), preferably silver. 1 or 2 selected from (Ag) and copper (Cu) is used. In this embodiment, Ag is used.

  The formation of the Ag layer 12 on one surface of the glass substrate 11 can be realized by a known vapor deposition method or sputtering method. In this embodiment, the mask member 14 in which the opening 13 corresponding to the width of the Ag layer 12 to be formed is pressed against one surface of the glass substrate 11 on which the Ag layer 12 is to be formed, and the mask member 14 side To form Ag by vapor deposition.

In the step shown in FIG. 1B, the Ag layer 12 is connected to the positive electrode side, the glass substrate 11 is grounded, a voltage (200 V in this embodiment) is applied to the glass substrate 11 and the Ag layer 12, and Ag Infiltrate into the glass substrate 11. At this time, sodium ions (Na ⁺ ) move to the ground side in the glass substrate 11, and Ag permeates into a region where Na ⁺ is reduced near the interface with the Ag layer 12. In the step shown in FIG. 1C, the Ag layer 12 is removed from the surface of the glass substrate 11 after the permeation treatment. The removal of the Ag layer 12 is easily realized by a process such as mechanical wiping.

  In the step shown in FIG. 1D, the metal substrate 15 is brought into contact with the surface of the glass substrate 11 on which Ag is infiltrated, the metal substrate 15 is connected to the positive electrode side, the glass substrate 11 is grounded, and the glass A voltage (500 V in this embodiment) is applied to the substrate 11 and the metal substrate 15 to anodic bond the glass substrate 11 and the metal substrate 15. In this embodiment, the silicon substrate 15 is illustrated as the metal substrate 15.

The behavior of the anodic bonding at this time is similar to the behavior in the case where the aforementioned Ag is not permeated into the glass substrate. That is, when the silicon substrate 15 is connected to the positive electrode side, the glass substrate 11 is grounded (equivalent to connecting to the negative electrode side), and a voltage is applied, the permeated Ag existing near the interface becomes Ag ^+. The glass substrate 11 moves toward the ground side, and a negative charge layer is formed in the vicinity of the interface between the glass substrate 11 and the silicon substrate 15, and a positive charge layer is formed in the vicinity of the interface with the silicon substrate 15. The glass substrate 11 and the silicon substrate 15 are brought into close contact with each other even at the molecular level due to the attractive force, and Si ⁺ of the adjacent silicon substrate 15 and O ^{2− of the} glass substrate 11 are bonded at the interface, and an anodic oxide (SiO ₂ ). A layer is formed, and the glass substrate 11 and the silicon substrate 15 are anodically bonded.

In the anodic bonding structure formed by the glass substrate 11 and the silicon substrate 15 formed in this way, Ag ⁺ is moved by voltage application during anodic bonding, and therefore, the bonding side of the glass substrate 11 bonded to the silicon substrate 15 is moved. Although it is located at a position slightly separated from the interface, an Ag infiltration layer is provided in the vicinity not far from the interface.

  FIG. 2 is a diagram for explaining the outline of the anodic bonding method according to the second embodiment of the present invention. Hereinafter, the anodic bonding method according to the second embodiment will be described with reference to FIG. This embodiment is similar to the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  In the step shown in FIG. 2A, the Ag layer 12 is formed in advance on one surface of the silicon substrate 15. In this embodiment, the Ag layer 12 is formed on the silicon substrate 15 side. The formation of the Ag layer 12 can be realized by a known vapor deposition method as in the first embodiment.

  In the step shown in FIG. 2B, the glass substrate 11 is brought into contact with the surface of the silicon substrate 15 on which the Ag layer 12 is formed, the silicon substrate 15 is connected to the positive electrode side, the glass substrate 11 is grounded, A voltage (500 V in this embodiment) is applied to the glass substrate 11 and the silicon substrate 15 to anodic bond the glass substrate 11 and the silicon substrate 15.

  According to this aspect, since the penetration of Ag into the glass substrate 11 and the bonding of the silicon substrate 15 to the glass substrate 11 can be performed simultaneously, a sound bonded portion can be secured even when a reverse voltage is applied. Anodic bonding can be realized more easily.

  FIG. 3 is a diagram for explaining the outline of the anodic bonding method according to the third embodiment of the present invention. Hereinafter, the anodic bonding method according to the third embodiment will be described with reference to FIG. This embodiment includes a step of further anodically bonding the silicon substrate 16 to the other surface side of the glass substrate 11 in the anodic bonding structure formed in the first or second embodiment. Therefore, the steps until the anodic bonding structure composed of the silicon substrate 15 and the glass substrate 11 is formed are the same as those in the first or second embodiment, and thus the description thereof is omitted.

  In the process shown in FIG. 3, another silicon substrate 16 (hereinafter referred to as the second silicon for convenience) is formed on the surface of the glass substrate 11 opposite to the side bonded to the silicon substrate 15 (hereinafter referred to as the first silicon substrate 15 for convenience). The second silicon substrate 16 is connected to the positive electrode side, the first silicon substrate 15 is grounded, and voltage is applied to the second silicon substrate 16, the glass substrate 11, and the first silicon substrate 15. (500 V in this embodiment) is applied, and the second silicon substrate 16, the glass substrate 11, and the first silicon substrate 15 are anodically bonded.

  In the case of this aspect, a reverse voltage is applied between the glass substrate 11 and the first silicon substrate 15 such that the glass substrate 11 is on the positive electrode side and the first silicon substrate 15 is on the negative electrode side. In this state, positive ions move in the glass substrate 11 toward the bonding interface with the first silicon substrate 15.

Here, as positive ions in the glass substrate 11, there are Na ⁺ originally contained in the glass substrate 11 and infiltrated Ag ⁺ . Among these amphoteric, as described above, Ag ^+, although moves to a position away from the bonding interface by the foregoing anodic bonding, present in Zaru before long position, Na ⁺ enriched formed by the movement of Na ⁺ The layer is located closer to the second silicon substrate 16 than the Ag ⁺ concentrated layer, that is, at a position farther from the bonding interface between the glass substrate 11 and the first silicon substrate 15. Therefore, when a reverse voltage is applied to the glass substrate 11 and the first silicon substrate 15, since the first Ag ⁺ is moved to integrated toward the bonding interface between the glass substrate 11 and the first silicon substrate 15, previously Ag ⁺ Na ⁺ cannot be accumulated in the region where the concentration is increased.

As a result, even when a reverse voltage is applied, it is possible to prevent Na ^+, which is an alkali metal ion, from being collected and leaked at the junction between the first silicon substrate 15 and the glass substrate 11. Occurrence of contamination, cracks, and peeling due to the above is prevented, and the soundness of the joint is ensured.

  Since a normal voltage is applied between the second silicon substrate 16 and the glass substrate 11, anodic bonding is performed in the same manner as shown in FIG. In addition, it is assumed that a reverse voltage is applied between the glass substrate 11 and the second silicon substrate 16, and prior to the bonding of the glass substrate 11 and the second glass substrate 16, Ag of Ag You may perform the penetration process to the glass substrate 11, or the formation process of the Ag layer 12 with respect to the 2nd silicon substrate 16. FIG.

  Examples of the present invention will be described below. Note that the present invention is not limited to the scope described in the embodiments, and various modifications are allowed without departing from the spirit of the present invention.

  In this example, a glass substrate that does not permeate Ag and a glass substrate that permeates Ag are prepared. After anodizing by applying a normal voltage to each of the silicon substrates, a reverse voltage is applied and a reverse voltage is applied. The integrity of the joint after application and the behavior of Ag and Na were tested.

  FIG. 4 is a perspective view showing the shapes and dimensions of the glass substrate 11 and the silicon substrate 15 used in this test. The glass substrate 11 used in this test is a borosilicate glass (Pyrex glass; registered trademark) having a disk shape with a thickness of 1 mm and a diameter of 25 mm, and its components are shown in Table 1. The silicon substrate 15 is a thin n-type semiconductor silicon substrate having a square shape with a thickness of 0.3 mm and a side length of 15 mm.

  FIG. 5 is a diagram showing a simplified configuration of the anodic bonding apparatus 20 used in the test. The anodic bonding apparatus 20 generally includes a chamber 21, a carbon heater 22 provided in the chamber 21, first and second electrodes 23 and 24, a voltage application power source 25 provided outside the chamber 21, and a voltage measurement circuit 26. And an evacuation system 27.

  The chamber 21 is a metal hollow container, and includes a door that can be opened and closed to enter and exit a sample 32 described later and can seal the space in the chamber 21, and an exhaust port for evacuating the internal space on the side wall. 28 is formed. A vacuum pump is connected to the exhaust port 28 and a pipe constituting the vacuum exhaust system 27 and the end of the pipe. Thereby, the anodic bonding apparatus 20 can make the space in the chamber 21 into a vacuum atmosphere.

  The carbon heater 22 is connected to a control power source (not shown) and can heat the sample 32 inserted in the space in the chamber 21 to a desired temperature. The first and second electrodes 23 and 24 are copper or copper alloy electrodes. In FIG. 5, the first electrode 23 is connected to the positive electrode side, and the second electrode 24 is connected to the negative electrode side. The reverse voltage can be applied to the sample 32 by reversing the connection to the voltage application power source 25. The voltage measurement circuit 26 includes a resistor 30 connected in series to a voltage application circuit 29 for the sample 32 and a voltmeter 31 connected in parallel to the resistor 30.

  In FIG. 5, the sample 32 has a configuration in which a normal voltage is applied in which the silicon substrate 15 is connected to the first electrode 23 on the positive electrode side and the glass substrate 11 is connected to the second electrode 24 on the negative electrode side. As described above, the reverse voltage can be obtained by reversing the connection of the first and second electrodes 23 and 24 to the voltage applying power source 25.

  In the chamber 21, a dummy sample 32a having the same configuration as the sample 32 and including a silicon substrate 15a and a glass substrate 11a is provided. A thermocouple 33 is connected to the dummy sample 32 a, and the temperature of the dummy sample 32 a can be measured by detecting the output of the thermocouple 33 with the digital voltmeter 34. The temperature of the sample 32 having the same configuration is obtained from the temperature of the dummy sample 32a.

  In this test, the comparative example sample is a combination of a glass substrate that is a borosilicate glass as obtained and a silicon substrate, and the example sample is a glass substrate obtained by performing Ag infiltration treatment on a borosilicate glass and a silicon substrate. It is a combination. Ag infiltration treatment for borosilicate glass was performed as follows. An Ag layer was formed on one surface of a glass substrate made of borosilicate glass by a known vapor deposition method. Next, the glass substrate on which the Ag layer is formed is inserted into the anodic bonding apparatus 20, the inside of the chamber 21 is evacuated, and then the glass substrate is heated to 290 ° C. with the carbon heater 22, and then the Ag layer is the first layer. The glass substrate was connected to the electrode 23, the glass substrate was connected to the second electrode 24, and a voltage of 200 V was applied for 600 seconds to infiltrate Ag into the glass substrate.

  With respect to the example sample and the comparative example sample, anodic bonding was performed by applying a normal voltage in which the silicon substrate was connected to the positive electrode side and the glass substrate was connected to the negative electrode side as the first time under the conditions shown in Table 2, The reverse voltage application was performed by reversing the electrode connection as the second time.

  The following tests were performed for each of the example samples and the comparative sample after the first anodic bonding and after the second reverse voltage application.

<Evaluation of soundness of joints>
FIG. 6 is a diagram illustrating the observation direction of the sample after anodic bonding and after application of a reverse voltage. The sample after anodic bonding and after application of the reverse voltage, that is, the overlapping silicon substrate 15 and glass substrate 11 is visually observed through the glass substrate 11 from the glass substrate 11 side as indicated by an arrow 35 in FIG. By observing and observing under a microscope, the presence or absence of defects such as cracks or delamination at the joint was investigated.

<Ag and Na Behavior at the Joint>
About the example sample and the comparative example sample, the vicinity of the joint was analyzed by Electron Probe Micro Analysis (EPMA) or Energy Dispersive X-ray Spectroscopy (EDS) to detect the state of concentration of Ag and Na.

The test results will be described below.
FIG. 7 shows the observation result after anodic bonding of the comparative sample, and FIG. 8 shows the observation result after anodic bonding of the example sample. At the stage where anodic bonding is performed by applying a normal voltage, there is no influence of the presence or absence of the Ag infiltration treatment on the glass substrate, and no defect is observed in the bonded portion in both the comparative sample and the example sample.

  FIG. 9 shows the observation results after applying the reverse voltage to the comparative sample, and FIG. 10 shows the observation results after applying the reverse voltage to the example sample. In the comparative sample in which the Ag infiltration treatment is not performed on the glass substrate shown in FIG. 9, a large number of abnormal portions 41 that are seen as spots are observed. FIG. 11 is an enlarged view of the spotted portion of the comparative sample shown in FIG. As a result of magnifying and observing the abnormal portion 41 with a microscope, these are the defects 41 in which cracks or peeling occurs.

  On the other hand, in the example sample in which the Ag infiltration treatment was performed on the glass substrate, no abnormal portion was observed. FIG. 12 is an enlarged view of the example sample shown in FIG. In the example sample, although some dirt 42 observed in a circular shape was observed, defects such as cracks or peeling were not recognized at all, and a healthy joint was maintained.

  FIG. 13 is a diagram showing the results of measuring the element distribution in the vicinity of the bonding interface of the comparative sample by EPMA. In the measurement result at the stage of anodic bonding shown in FIG. 13A, the concentration of Na in the vicinity of the bonding interface between the glass substrate and the silicon substrate is hardly recognized. In the result of measuring the discolored region that looks like the spots after the reverse voltage application shown in FIG. 13B, the concentration of Na is clearly recognized in the vicinity of the bonding interface. In addition, in the result of measuring the non-discoloring region that is a portion other than the spotted shape after the reverse voltage application shown in FIG. From the results of FIG. 13B and FIG. 13C, it can be seen that when the reverse voltage is applied, Na is concentrated and concentrated in the vicinity of the junction interface, and defects are generated when the degree of concentration of Na is increased.

  FIG. 14 is a diagram showing the results of elemental analysis of the vicinity of the bonding interface of the example sample by EDS. FIG. 14A shows an element analysis position in the vicinity of the bonding interface 43 between the glass substrate 11 and the silicon substrate 15. A line 43 extending from the upper left to the lower right toward the middle sheet surface of FIG. In FIG. 14A, uppercase alphabets A to D are elemental analysis positions. The position D is on the bonding interface 43, and the distance from the bonding interface increases in the order of the positions C, B, and A below.

  FIG. 14B shows the result of elemental analysis. At position D on the bonding interface 43, it is clearly recognized that Ag is accumulated and concentrated, and Na is not concentrated. At a position C slightly separated from the bonding interface 43, the concentration of Ag is low, and conversely, the concentration of Na is recognized. Concentration of Ag and Na is not observed at positions B and A that are further away from the bonding interface 43 than at position C.

  In the example sample, when a reverse voltage is applied, the permeated Ag first moves to the bonding interface 43 and accumulates and concentrates, so there is no room for Na to accumulate at the bonding interface 43, and the Ag accumulation and concentration portion Accumulation and concentration can be performed only at a position C separated from the bonding interface 43 which is the rear. As described above, in the example sample, Na does not concentrate and accumulate at the bonding interface 43, and therefore does not leak at the bonding interface 43, and does not cause cracking and peeling, and a reverse voltage is applied. But a healthy joint is ensured.

  As described above, in the present embodiment, the metal substrate bonded to the glass substrate is a silicon substrate, but is not limited to this, and may be another semiconductor substrate or other than the metal substrate. Alternatively, a metal element-containing substrate, for example, a ceramic substrate may be used.

It is a figure explaining the outline of the anodic bonding method which is a 1st aspect of implementation of this invention. It is a figure explaining the outline of the anodic bonding method which is the 2nd aspect of implementation of this invention. It is a figure explaining the outline of the anodic bonding method which is the 3rd aspect of implementation of this invention. It is a perspective view which shows the shape and dimension of the glass substrate 11 and silicon substrate 15 which were used in this test. It is a figure which simplifies and shows the structure of the anodic bonding apparatus 20 used for the test. It is a figure which shows the observation direction of the sample after anodic bonding and a reverse voltage application. It is an observation result after anodic bonding of a comparative example sample. It is an observation result after anodic bonding of an example sample. It is an observation result after reverse voltage application of a comparative example sample. It is an observation result after reverse voltage application of an example sample. It is a figure which expands and shows the spot-like part of the comparative example sample shown in FIG. It is a figure which expands and shows the Example sample shown in FIG. It is a figure which shows the result of having measured the element distribution by EPMA in the joining interface vicinity of a comparative example sample. It is a figure which shows the result of having carried out the elemental analysis by EDS in the joining interface vicinity of an Example sample. It is a schematic diagram which shows the outline of the anodic bonding method of the glass substrate 1 and the silicon substrate 2. FIG. It is a schematic diagram which shows the outline of the method of anodic bonding a silicon substrate and a glass substrate in multiple layers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Glass substrate 12 Ag layer 15 Silicon substrate 16 Another silicon substrate 20 Anodic bonding apparatus 21 Chamber 22 Carbon heater 23, 24 Electrode 25 Voltage application power supply 27 Vacuum exhaust system

Claims (8)

In the anodic bonding method for bonding a glass substrate and a metal substrate or a metal element-containing substrate,
Forming a movable metal layer comprising a movable metal in a glass substrate in advance on one surface of the glass substrate;
Connecting the movable metal layer to the positive electrode side and applying a voltage to the glass substrate and the movable metal layer to infiltrate the movable metal into the glass substrate;
Removing the movable metal layer from the surface of the glass substrate;
A metal substrate or a metal element-containing substrate is brought into contact with the surface of the glass substrate on which the movable metal is infiltrated, and the metal substrate or the metal element-containing substrate is connected to the positive electrode side. An anodic bonding method comprising: applying a voltage to the substrate and bonding the glass substrate and the metal substrate or the metal element-containing substrate. In the anodic bonding method for bonding a glass substrate and a metal substrate or a metal element-containing substrate,
Forming a movable metal layer comprising a movable metal in a glass substrate in advance on one surface of the metal substrate or the metal element-containing substrate;
The glass substrate is brought into contact with the surface of the metal substrate or the metal element-containing substrate on which the movable metal layer is formed, the metal substrate or the metal element-containing substrate is connected to the positive electrode side, and the glass substrate and the metal substrate or metal element are connected. An anodic bonding method comprising: applying a voltage to the containing substrate, and bonding the glass substrate and the metal substrate or the metal element-containing substrate.   Another metal substrate or metal element-containing substrate is brought into contact with the surface of the glass substrate opposite to the side bonded to the metal substrate or metal element-containing substrate, and the other metal substrate or metal element-containing substrate is brought to the positive electrode side. Connecting, applying a voltage to another metal substrate or metal element-containing substrate and glass substrate and metal substrate or metal element-containing substrate, another metal substrate or metal element-containing substrate and glass substrate and metal substrate or metal element The anodic bonding method according to claim 1, further comprising a step of bonding the containing substrate.   4. The anodic bonding method according to claim 1, wherein the movable metal is 1 or 2 selected from silver and copper.   The anodic bonding method according to claim 1, wherein the metal substrate is a silicon substrate.   The anodic bonding method according to any one of claims 1 to 4, wherein the metal element-containing substrate is a ceramic substrate. An anodic bonding structure formed by bonding a glass substrate and a metal substrate or a metal element-containing substrate,
An anodic bonding structure characterized in that a permeation layer of a movable metal element in a glass substrate is provided in the vicinity of a bonding side interface of the glass substrate bonded to the metal substrate or the metal element-containing substrate.   8. The anodic bonding structure according to claim 7, wherein the movable metal element is 1 or 2 selected from silver and copper.