JPH07299911A - Substrate bonding method and inkjet head manufacturing method using the method - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for joining substrates in which the diaphragm is not warped even by anodic bonding. A first substrate, at least a part of which is formed thinner than the second substrate, and a second substrate made of a material different from that of the first substrate.
In the method of joining substrates described in (1) above using anodic bonding, the relationship between the shrinkage amount ε1 of the first substrate and the shrinkage amount ε2 of the second substrate when cooled from the joining temperature Tb to the room temperature Tr is εsi ≧ A bonding method for a substrate, wherein a bonding temperature Tb satisfying εPy is obtained in advance, and then the first substrate and the second substrate are bonded by anodic bonding at the bonding temperature Tb.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding substrates by anodic bonding, and more particularly to the bonding temperature of the anodic bonding.
The present invention also relates to application to a method for manufacturing an inkjet head using anodic bonding.

[0002]

2. Description of the Related Art In anodic bonding, two insulating or semiconductor substrates made of glass, silicon or the like are superposed and heated, and then a high voltage is applied between the substrates, for example, a positive movable state existing in the glass. This is a method of attracting ions to the cathode and joining the other substrate with the negative ions remaining on the anode side, which is a method of joining the two substrates relatively reliably.

For example, the ink jet head disclosed in Japanese Patent Application Laid-Open No. 2-80252 has an ink-on
The demand method is used, and the substrates, diaphragms, etc. are joined by anodic bonding. Since this anodic bonding has a strength of 40% of that of the base material, it has attracted attention as a useful bonding method in the production of this type of inkjet head.

Further, Japanese Unexamined Patent Publication No. 2-289351 discloses an actuator which uses an electrostatic attraction force, and this method enables high quality (high resolution) printing.

[0005]

For example, in the above-mentioned actuator of the ink jet head which utilizes the attraction force due to static electricity, the flow path substrate (S
i) and a cover glass (Pyrex glass) and an electrode glass (Pyrex glass) sandwiched between them, and in manufacturing them, it is necessary to bond these substrates and glass by anodic bonding to obtain a strength or vibration plate. It is considered desirable from the viewpoint of processing accuracy of the gap between the electrode and the electrode. However, in order to increase the resolution and drive at a low voltage in the range commonly used as a printer, it is necessary to make the diaphragm thinner than the glass on both sides of the diaphragm. However, there is a problem in that it may not function as an inkjet head. Thus, in the method of anodic bonding a substrate having a particularly thin film on one substrate to the other substrate, not only the inkjet head, the problem that a desired film cannot be obtained after bonding Had.

The present invention has been made in order to solve the above problems, and a method of joining substrates by anodic bonding in which the vibration plate does not warp even by anodic bonding, and an ink jet applying the same. An object is to provide a method for manufacturing a head.

[0007]

According to a method of joining substrates of the present invention, a first substrate, at least a part of which is formed thinner than a second substrate, and a second substrate made of a material different from that of the first substrate. In a substrate bonding method for bonding substrates using anodic bonding, a first substrate is bonded to a temperature range T including a room temperature T _r .
A first function α ₁ (T) indicating the coefficient of linear expansion of the substrate and a second function α ₂ (T) indicating the coefficient of linear expansion of the second substrate, and the first function and Calculating a junction temperature T _b that satisfies the following equation from the second function;

[0008]

[Equation 4]

[0009] The junction temperature T _b to said first substrate and said heating the second substrate, the while maintaining the bonding temperature T _b first substrate and the second predetermined time voltage between the substrates And a step of stopping the application of the voltage and cooling the anodic-bonded substrate to room temperature.

According to the method of manufacturing an ink jet head of the present invention, the nozzle, the ink flow path communicating with the nozzle, the vibration plate formed in a part of the flow path, and the vibration plate facing each other with a gap therebetween. In the method of manufacturing an ink jet head, which has an electrode formed by applying an electric pulse between the vibrating plate and the electrode, deforms the vibrating plate by an electrostatic force, and ejects ink droplets from the nozzle. A step of forming the flow path and the vibration plate on a first substrate; a step of forming the electrode on a second substrate thicker than the first substrate; a step of forming the first substrate and the second substrate; Heating the substrates to a bonding temperature T _b , applying a voltage between the substrates for a predetermined time to anodic bond the substrates, and each of the first substrates for a temperature T range including room temperature T _r. First function α indicating the linear expansion coefficient of The relationship between ₁ (T), the second function α ₂ (T) indicating the linear expansion coefficient of the second substrate, and the junction temperature T _b is

[0011]

[Equation 5]

It is characterized in that

Silicon is a preferred material for the first substrate, and Pyrex glass is a preferred material for the second substrate.

[0014]

When the first substrate and the second substrate or the first substrate and the third substrate are anodic-bonded to each other, the anodic bonding is performed at a relatively high temperature. These substrates shrink. The diaphragm of the first substrate warps depending on the amount of shrinkage, but in the present invention, the bonding temperature is set to the second substrate when the shrinkage amount of the first substrate is set to the second
Since the temperature range is set to be equal to or larger than the contraction amount of the first substrate or the third substrate, even if the diaphragm formed on the first substrate is thinned, the phenomenon that the diaphragm warps can be avoided.
You can expect normal operation.

[0015]

FIG. 2 is an exploded perspective view of an ink jet head to which the present invention is applied, which is a partial sectional view. This embodiment shows an example of an edge eject type in which ink droplets are ejected from nozzle holes provided at the end of the substrate, but a face ejecting ink droplets from nozzle holes provided at the upper surface of the substrate is used. It may be an eject type.
3 is a sectional side view of the assembled inkjet head, and FIG. 4 is a view taken along the line AA of FIG. The inkjet head 10 of the present embodiment has a laminated structure in which three substrates 1, 2 and 3 having a structure described in detail below are stacked and joined. The first intermediate substrate 1 is a silicon substrate,
A plurality of nozzle grooves 11 formed on the surface of the substrate 1 in parallel from one end at equal intervals so as to form a plurality of nozzle holes 4.
And a recess 12 communicating with each nozzle groove 11 and forming a discharge chamber 6 having a bottom wall as a vibrating plate 5, and a recess 12
A narrow groove 13 for forming an ink inlet to form an orifice 7 provided in the rear portion and a recess 14 forming a common ink cavity 8 for supplying ink to each ejection chamber 6. Have and. Further, in the lower part of the vibration plate 5, there is provided a concave portion 15 which constitutes the vibration chamber 9 for mounting electrodes described later.

In this embodiment, the distance between the vibrating plate 5 and the electrodes arranged opposite thereto, that is, the gap portion 1
A length G of 6 (see FIG. 3, hereinafter referred to as “gap length”).
So that there is a difference between the depth of the recess 15 and the thickness of the electrode,
The space holding means is composed of a vibration chamber recess 15 formed on the lower surface of the first substrate 1. As another example, the recess may be formed on the upper surface of the second substrate 2. Here, the depth of the recess 15 is set to 0.6 μm by etching. The pitch of the nozzle grooves 11 is 0.72 mm and the width thereof is 70 μm.

Regarding the provision of the common electrode 17 to the first substrate 1, it is important that the work function of the metal material of the semiconductor and the electrode is large or small. In this embodiment, titanium is used as the common electrode material. Although platinum is used as an attachment and gold is used as an underlay of chromium, the present invention is not limited to this embodiment, and another combination may be used depending on the characteristics of the semiconductor and the electrode material.

Borosilicate glass is used for the lower second substrate to be bonded to the lower surface of the first substrate 1, and the vibration chamber 9 is formed by bonding the second substrate 2 to the second substrate.
Gold is sputtered by 0.1 μm on each position corresponding to the vibration plate 5 on the substrate 2, and a gold pattern is formed in substantially the same shape as the vibration plate 5 to form the individual electrodes 21. Individual electrode 2
1 has a lead portion 22 and a terminal portion 23. Furthermore, except for the electrode terminal portion 23, a Pyrex sputtered film is formed on the entire surface by 0.2
An insulating layer 24 is formed by coating with a thickness of μm to form a film for preventing dielectric breakdown and short circuit when the inkjet head is driven.

The upper third substrate 3 bonded to the upper surface of the first substrate 1 is made of borosilicate glass, like the second substrate 2. By joining the third substrate 3, the nozzle hole 4, the ejection chamber 6, the orifice 7, and the ink cavity 8 are formed. Further, the third substrate 3 is provided with an ink supply port 31 communicating with the ink cavity 8. The ink supply port 31 is connected to an ink tank (not shown) via a connection pipe 32 and a tube 33.

Next, the first substrate 1 and the second substrate 2 are anodically bonded at a temperature of 270 to 400 ° C. and a voltage of 500 to 800 V, and under the same conditions, the first substrate 1 and the third substrate 2 are joined together. 3, and the ink jet head is assembled as shown in FIG. The details of the assembly by this anodic bonding will be described later. After anodic bonding, the diaphragm 5 and the second substrate 2
Gap length G formed between the upper individual electrode 21
Is the difference between the depth of the recess 15 and the thickness of the individual electrode 21, which is 0.5 μm in this embodiment. The gap G1 between the diaphragm 5 and the insulating layer 24 on the individual electrode 21 is 0.3 μm.

After the ink jet head is assembled as described above, the common electrode 17 and the terminal portion 23 of the individual electrode 21 are formed.
A drive circuit 102 is connected between the wirings 101 to form an inkjet printer. Ink 103
Is supplied to the inside of the first substrate 1 from an ink tank (not shown) through the ink supply port 31, and fills the ink cavity 8, the ejection chamber 6, and the like. Then, as shown in FIG. 3, the ink in the ejection chamber 6 is ejected as ink droplets 104 from the nozzle holes 4 when the inkjet head 10 is driven, and is printed on the recording paper 105.

FIG. 5 is an explanatory view of the above-mentioned anodic bonding. As described above, the DC voltage of 500 to 800 V is applied to the electrodes 41 and 4 on the first substrate 1 such as Si and the second substrate 2 such as Pyrex glass under the environment of the temperature of 270 to 400 ° C.
It is applied via 2 to perform anodic bonding. Similarly, a DC voltage of 500 to 80 is applied to the first substrate 3 and the third substrate 3 such as Pyrex glass under an environment of a temperature of 270 to 400 ° C.
0V is applied through the electrodes 41 and 42 to perform anodic bonding.

FIG. 6 is an explanatory diagram showing the strain acting on the substrates 1, 2, and 3 at room temperature after anodic bonding. Here, when the amount of shrinkage of the substrates 2 and 3 is larger than the amount of shrinkage of the substrate 1, a compressive force acts on the vibration plate 5 of the substrate 1 to warp it. When the contraction amount is the same as or larger than the contraction amounts of 2 and 3, no stress is applied to the diaphragm 5, or even if it is applied, only the tension acts and the diaphragm 5 does not warp. In this way, the substrate 1,
The vibrating plate 5 may or may not warp depending on the amount of shrinkage of 2, 3 depending on the temperature at the time of anodic bonding and the linear expansion coefficient of the substrates 1, 2, 3. This point will be described below.

The shrinkage amount Δl of the substrate or the like is expressed by the following equation. In the following equation, α is a coefficient of linear expansion and ΔT is a temperature change.

[0025]

[Equation 6]

Here, when the contraction amounts of the first substrate 1 and the second substrate 2 are εsi and εPy, respectively, they are expressed by the following equations.

[0027]

[Equation 7]

Tb is the junction temperature, Tr is the temperature at the time of use (for example, room temperature), αsi (T) is the linear expansion coefficient of the first substrate 1, and αPy (T) is the linear expansion coefficient of the second substrate 2. Is.
As described above, when the contraction amount εsi of the first substrate 1 is equal to or larger than the contraction amount εPy of the second substrate 2, the warpage of the diaphragm 5 does not occur, so that the linear expansion coefficient αsi.
By measuring (T) and αPy (T) in advance, a junction temperature Tb satisfying the following equation is obtained.

[0029]

[Equation 8]

FIG. 1 is a characteristic diagram showing the relationship between the anodic bonding temperature and the linear expansion coefficient. Pyrex glass shows the property that the coefficient of linear expansion differs from lot to lot. In the illustrated example, # 1 shows an example of a lot having a relatively large linear expansion coefficient, and # 2 shows a lot having a relatively small linear expansion coefficient. An example is shown. The # 1 Pyrex glass satisfies the above formula (3) at a joining temperature of 300 ° C or higher, and the # 2 Pyrex glass has a joining temperature of 215 ° C.
In the above, the above formula (3) is satisfied. Therefore,
It is understood that the # 1 Pyrex glass should be anodically bonded at a bonding temperature of 300 ° C. or higher, and the # 2 Pyrex glass should be bonded at a bonding temperature of 215 ° C. or higher. However, if the joining temperature exceeds 400 ° C, the tensile stress becomes too large and the diaphragm 5 may be damaged. Therefore, the upper limit of the joining temperature is preferably 400 ° C.

Further, paying attention to # 1 Pyrex glass, even if the bonding temperature is 300 ° C. or less, ±
As long as the warp is within 500 (angstrom), there is no problem in practical use, so the bonding temperature may be 270 ° C or higher.
Further, when the variation in the characteristics of the Pyrex glass between lots is taken into consideration, the bonding temperature range is 270 ° C to 4 ° C.
It becomes 00 ° C. More desirable in this temperature range is the range of 270 ° C to 330 ° C, and more desirable in that temperature range is the range of 300 ° C to 330 ° C. Since the range of the bonding temperature of the # 1 Pyrex glass also satisfies the condition of the bonding temperature of the # 2 Pyrex glass, a Pyrex glass having a characteristic in a high temperature range of the bonding temperature is required. As a standard, anodic bonding can be performed at a uniform bonding temperature regardless of the characteristics of other Pyrex glass.

In the above embodiments, the method for manufacturing an ink jet head has been described as an example, but the present invention is not limited to the method for manufacturing an ink jet head.
The present invention can be applied to a method of manufacturing an overall device having the same problem, for example, using anodic bonding and having an electrostatic actuator formed by bonding two or more substrates.

[0033]

As described above, according to the present invention, the first
Of the first substrate and the second substrate, or the first substrate and the third substrate by anodic bonding, and the contraction amount of the first substrate after bonding at the bonding temperature is equal to that of the second substrate or the third substrate. Since the temperature range is set to be equal to or larger than the amount of contraction, even if the diaphragm formed on the first substrate is thinned, the phenomenon that the diaphragm warps can be avoided, and normal operation can be expected.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between a bonding temperature and a coefficient of thermal expansion.

FIG. 2 is an exploded perspective view of the ink jet head of the embodiment.

FIG. 3 is a cross-sectional side view of the inkjet head of the embodiment.

FIG. 4 is a view taken along the line AA of FIG.

FIG. 5 is an explanatory diagram of anodic bonding.

FIG. 6 is an explanatory diagram of warpage of the diaphragm.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadaaki Hakata 3-3-5 Yamato, Suwa, Nagano Seiko Epson Corporation (72) Inventor Yoshio Maeda 3-5 Yamato, Suwa, Nagano Prefecture Seiko -In Epson Corporation (72) Inventor Hiroshi Komatsu 3-3-5 Yamato, Suwa City, Nagano Seiko-In Epson Corporation

Claims (5)

[Claims] 1. A method of joining a substrate, wherein at least a part of the first substrate is formed thinner than the second substrate, and the second substrate made of a material different from that of the first substrate is joined by anodic bonding. In the range of the temperature T including the room temperature T _r , a first function α ₁ (T) showing the linear expansion coefficient of the first substrate and a second function showing the linear expansion coefficient of the second substrate, respectively. a step of obtaining α ₂ (T), a step of calculating a junction temperature T _b satisfying the following expression from the first function and the second function, and Heating the first substrate and the second substrate to the bonding temperature T _b, to apply a predetermined time the voltage between the while keeping the junction temperature T _b first substrate and the second substrate And a step of cooling the anodic-bonded substrate to room temperature by stopping the application of the voltage. 2. The first substrate is made of silicon,
The substrate bonding method according to claim 1, wherein the second substrate is made of Pyrex glass. 3. A nozzle, an ink flow path communicating with the nozzle, a vibration plate formed in a part of the flow path, and an electrode formed facing the vibration plate with a gap therebetween, In the method of manufacturing an inkjet head, in which an electric pulse is applied between the vibrating plate and the electrode, the vibrating plate is deformed by an electrostatic force, and ink droplets are ejected from the nozzles, the flow path and the vibrating plate are Forming the electrode on a second substrate thicker than the first substrate; heating the first substrate and the second substrate to a bonding temperature T _b ; A step of applying a voltage between the substrates for a predetermined time to perform anodic bonding of the substrates, and a first function α indicating the coefficient of linear expansion of each of the first substrates with respect to a temperature range T including a room temperature T _{r. 1} (T) and the second relationship showing the linear expansion coefficient of the second substrate. The relationship between the number α ₂ (T) and the junction temperature T _b is as _follows : A method for manufacturing an inkjet head, characterized in that: 4. The first substrate and a third substrate that covers the first substrate are further anodic-bonded at a bonding temperature T _b, and the third substrate is formed in a range of a temperature T including a room temperature T _r . The relationship between the third function α ₃ (T) indicating the linear expansion coefficient of the substrate, the first function α ₁ (T), and the junction temperature T _b is as _follows. 4. The method of manufacturing an inkjet head according to claim 3, wherein 5. The first substrate is made of silicon,
The method for manufacturing an inkjet head according to claim 3, wherein the second and third substrates are made of Pyrex glass.