JP2005144774A - Method for manufacturing liquid discharge head - Google Patents

Abstract

A glass diaphragm material to be anodically bonded to a flow path substrate is preheated and thermally contracted to prevent troubles caused by thermal contraction of the diaphragm when a piezoelectric element is directly formed on the diaphragm.
A glass diaphragm material 6a is preheated to, for example, 650 ° C. to cause a pre-shrinkage of 0.2%, and then anodically bonded to a flow path substrate 1, and the glass diaphragm material 6a is polished into thin pieces. A diaphragm 6 having a predetermined thickness is manufactured. By sequentially laminating the lower electrode 9a, the piezoelectric precursor layer 8a to be the piezoelectric layer 8 and the upper electrode 9b on the vibration plate 6, the piezoelectric element 7 is directly formed on the vibration plate 6, and the crystallization temperature of the piezoelectric material is reached. The piezoelectric layer 8 is crystallized by heating. By preventing thermal contraction of the diaphragm 6 in the second heating step for crystallization, troubles such as deformation of the flow path substrate 1 and cracks in the diaphragm 6 are avoided.
[Selection] Figure 2

Description

  The present invention relates to a liquid discharge head used in a printer or the like, and more particularly to a method of manufacturing a liquid discharge head that discharges liquid using a piezoelectric element.

  In recent years, liquid discharge recording apparatuses such as ink jet printers have become widespread as recording apparatuses that perform high-quality printing. Such a liquid discharge recording apparatus is expected to have a very wide application such as printing, industrial chemicals, and application of pattern materials as well as printing applications. As a typical liquid discharge head used in a liquid discharge recording apparatus, there are a piezoelectric type using a piezoelectric element and a thermal type using heating by a heater, both of which have been developed with high performance.

What has excellent characteristics as a piezoelectric liquid discharge head, and uses a glass diaphragm bonded to the flow path substrate by anodic bonding as a vibration plate for applying pressure to the pressure generation chamber of the flow path substrate (See Patent Document 1). As shown in FIG. 4, a flow path substrate 101 made of silicon forming a pressure generating chamber 102, a nozzle 103, an orifice 104, a liquid supply chamber 105, etc., and a borosilicate glass plate that is a material of a glass diaphragm The borosilicate glass plate is thinned to a predetermined thickness to form a diaphragm 106, and an electrode layer 109a, which is a lower electrode of the piezoelectric element 107, is formed on the surface of the diaphragm 106. performs bonding of the piezoelectric element plate 108, thinning the piezoelectric plate 108 to a predetermined thickness, further forming an electrode layer 109b is an upper electrode, by performing the removal processing of the unnecessary portion to produce a liquid discharge head E ₀ ing.

  According to this method, a diaphragm having a thickness of 0.1 mm or less can be realized at a mass production level, and a liquid discharge head having high performance, small size and light weight and excellent mass productivity can be provided. Also, the anode anodic bonding of the vibration plate can realize a strong direct bonding without an inclusion such as an adhesive at the position of the liquid discharge head in contact with the liquid such as ink, so that the liquid discharge head is highly stable with respect to the liquid such as ink. It is.

  The anodic bonding is a bonding method using electrostatic attraction generated by movement of alkali ions in the glass caused by heating the glass and applying a voltage. Such a bonding method is disclosed in Patent Document 2 and the like. .

In all of the above conventional examples, this anodic bonding is described as “electrostatic bonding”, but such a bonding method is generally referred to as anodic bonding (for example, non-patent literature). 1), hereinafter referred to as anodic bonding.
Japanese Patent Laid-Open No. 9-094965 JP-A-6-326331 "Micro Machining and Micro Mechatronics" published by Baifukan Co., Ltd. SID93 Digest of Technical Papers, p. 971

However, the vitreous material used as the glass diaphragm has a denser structure during the heating process, for example, when heat treatment is required to heat to high temperature and cool to room temperature for crystallization of the piezoelectric element. When trying to stabilize, the volume at room temperature after the heating process may be so-called thermal shrinkage that significantly decreases the volume at room temperature before the heating process (Non-patent Document 2). The amount of heat shrinkage varies depending on the glass composition, the manufacturing process, the temperature conditions of the heating process, and the like, but when the heating process is performed at a high temperature in the vicinity of the strain point, the thermal shrinkage ratio C = (L ₀ -L ₁ ) / L ₀ (C: heat shrinkage ratio, L ₀ : size of glass sample at room temperature before heating step, L ₁ : size of glass sample at room temperature after heating step) is 0.1% or more. There is a case. On the other hand, silicon used as a flow path substrate hardly undergoes thermal shrinkage in the heating process.

  For this reason, in a liquid discharge head that uses a glass material for the diaphragm for applying pressure to the pressure generating chamber and silicon for the flow path substrate having the pressure generating chamber, respectively, When the heat treatment is performed after the bonding, the glass diaphragm is thermally contracted and a relatively large compressive stress may be applied to the flow path substrate made of silicon. In particular, in recent years, a configuration in which the piezoelectric element is directly deposited on the glass diaphragm after the anodic bonding process has been proposed. However, when a high-temperature heat treatment necessary to crystallize the deposited piezoelectric layer is performed. In addition, due to the heat shrinkage of the glass diaphragm, a large deformation of the flow path substrate, cracks in the glass diaphragm, and the like occur, thereby reducing the yield. For this reason, it is difficult to directly form a piezoelectric element on the glass diaphragm.

  On the other hand, in the conventional example disclosed in Patent Document 1, the piezoelectric element plate and the vibration plate are joined with an adhesive interposed therebetween, but in this configuration, the piezoelectric element effectively vibrates glass. It was necessary to change the total amount of the plate and the adhesive, and the liquid could not be discharged efficiently. In particular, when the nozzles of the liquid discharge head are arranged at a high density in order to improve the recording density, the piezoelectric element is miniaturized and thinned, so the problem due to the presence of an adhesive that affects the discharge efficiency is serious.

  The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and effectively avoids troubles caused by thermal contraction of the glass diaphragm and directly forms a piezoelectric element on the glass diaphragm. It is an object of the present invention to provide a method of manufacturing a liquid discharge head capable of manufacturing a liquid discharge head having high discharge efficiency with high nozzle efficiency and high yield.

  In order to achieve the above object, a method for manufacturing a liquid discharge head according to the present invention is a method for manufacturing a liquid discharge head in which a liquid in a pressure generating chamber is pressurized by a piezoelectric element on a glass diaphragm and discharged from a nozzle. A step of preparing a flow path substrate having a pressure generating chamber and a nozzle, a first heating step of heating the glass vibrating plate material to a predetermined temperature, and a bonding step of bonding the glass vibrating plate material to the flow path substrate by anodic bonding Forming a piezoelectric element by sequentially laminating an electrode layer and a piezoelectric layer on a glass diaphragm made of a glass diaphragm material, and crystallizing the piezoelectric layer during or after lamination on the glass diaphragm. And a second heating step for heating to a temperature for the purpose.

  Between the bonding step and the forming step, it is preferable to have a step of polishing and laminating the glass diaphragm material to form a glass diaphragm having a predetermined thickness.

  The temperature of the first heating step may be set so that the thermal contraction rate of the glass diaphragm in the second heating step is 0.01% or less.

  A glass diaphragm is prepared by heat-shrinking a diaphragm material to be a glass diaphragm in advance to a predetermined temperature and suppressing a dimensional change of the glass diaphragm in the heat treatment for crystallizing the piezoelectric layer. It enables direct formation of a piezoelectric element having a piezoelectric layer laminated thereon. As a result, a liquid discharge head having high discharge efficiency in which nozzles are arranged at high density can be manufactured with high yield.

  By preliminarily setting the temperature condition of the first heating step for heat shrinking so as to suppress the thermal shrinkage of the glass diaphragm in the second heating step to 0.01% or less, liquid discharge with higher yield is achieved. It is possible to manufacture a head.

  By mounting such a liquid ejection head on a recording apparatus, a recording apparatus with high ejection efficiency in which nozzles are arranged at high density can be manufactured at low cost.

As shown in FIG. 1, the flow path substrate 1 has a pressure generation chamber 2, a nozzle 3, an orifice 4, and a liquid supply chamber 5, and thus has a pressure generation chamber 2 that communicates with the nozzle 3. 1, a diaphragm 6, which is a glass diaphragm, is anodically bonded, and a piezoelectric element 7 is directly formed on the diaphragm 6. The piezoelectric element 7 is formed by depositing and laminating upper and lower electrodes 9 a and 9 b that are electrode layers and a piezoelectric layer 8 on the diaphragm 6. The manufacturing process of the liquid discharge head E ₁ includes at least a first heating process for heat-shrinking the glass diaphragm 6 in advance, and a flow having the pressure generating chamber 2 and the like by anodic bonding through the first heating process. A step of sequentially depositing and laminating the upper and lower electrodes 9a and 9b and the piezoelectric layer 8 on the diaphragm 6 bonded to the road substrate 1, and a second step of crystallizing the piezoelectric layer 8 during or after the deposition. Heating step.

  And the temperature conditions of the 1st heating process which fully contracts the diaphragm 6 are set so that the thermal contraction rate of the diaphragm 6 in a 2nd heating process may be 0.01% or less. The upper and lower electrodes 9a and 9b and the piezoelectric layer 8 are formed on the diaphragm 6 which is sufficiently heat-shrinked by the first heating process and bonded to the flow path substrate 1 by anodic bonding, and then the piezoelectric layer 8 is crystallized. Since the second heating step is performed, the dimensional change of the vibration plate 6 in the step of crystallizing the piezoelectric layer 8 is very small, and the flow path substrate 1 is significantly deformed or cracks are generated in the vibration plate 6. There is no trouble such as occurrence, and therefore the liquid discharge head can be manufactured with high yield.

  A plurality of liquid discharge heads manufactured by the above method are arranged, and a lead electrode for applying a drive signal to the piezoelectric element, a drive voltage applying circuit for driving the piezoelectric element, a nozzle opening of the liquid discharge head, and a recording medium A recording apparatus having a supporting member for making it face at a desired distance, a mechanism for changing the relative position between the nozzle opening of the liquid ejection head and the recording medium in accordance with input information, and the like are manufactured.

The liquid discharge head E ₁ shown in FIG. 1 is manufactured by the process shown in FIG. A glass diaphragm material 6a having a length L ₀ was prepared as shown in FIG. As the glass diaphragm material 6a, anodic bonding glass was used. This glass can be anodically bonded and is appropriately selected from those having a softening point at a temperature sufficiently higher than the heating temperature in the subsequent direct forming process of the piezoelectric element 7. In this example, HOYA trademark SD2 glass was used as the glass for anodic bonding. Other preferred examples include crystallized glass, Davidon “Hα-43” manufactured by Ishizuka Glass Co., Ltd. The glass diaphragm material 6a was a square having a thickness of 50 μm and a side of 50.00 mm. The length L ₀ shown in (a) of FIG. 2 is obtained by measuring the length of one side of the glass diaphragm material 6a using a laser length measuring instrument in a temperature-controlled room at 25 ° C. In this example, L ₀ = 50.00 mm.

Subsequently, as shown in FIG. 2 (b), a first heating step for preliminarily shrinking the glass diaphragm material 6a was performed. The first heating step was performed using an electric furnace in an air atmosphere at a maximum heating temperature of 650 ° C. and a heating time of 5 hours, and then cooled to room temperature. The illustrated length L ₁ is obtained by measuring the length of one side of the glass diaphragm material 6a using a laser length measuring instrument in a temperature-controlled room at an air temperature of 25 ° C. after the first heating step. L ₁ = 49.90 mm. That is, in the first heating step, the glass diaphragm material 6a was preliminarily shrunk by 0.2% in the length of one side.

  Subsequently, as shown in FIG. 2C, a silicon nitride film having a thickness of 300 nm is formed by LP-CVD on both surfaces of the double-side polished silicon single crystal substrate 1a with the plane orientation (100). Second mask layers 10a and 10b were formed.

Subsequently, as shown in FIG. 2D, the first mask opening 10c is formed in the first mask layer 10a, and the second mask layer is processed by dry etching using a photolithography technique and a gas containing CF _4. A second mask opening 10d was formed in 10b. The planar shape of the mask openings 10c and 10d is determined so that a plurality of pressure generating chambers 2, orifices 4, liquid supply chambers 5 and nozzles 3 having a desired shape can be obtained by anisotropic etching in a later step. did.

  Subsequently, as shown in FIG. 2 (e), first, the silicon single crystal substrate 1a is anisotropically etched from the first mask opening 10c using a TMAH solution, and the pressure generating chamber 2, the nozzle 3, and the orifice 4 are then etched. Formed. Similarly, anisotropic etching was performed from the second mask opening 10 d to form a liquid supply chamber 5 communicating with the pressure generating chamber 2 through the orifice 4.

  Subsequently, as shown in FIG. 2 (f), the first and second mask layers 10a and 10b were removed by etching to expose the silicon surface, whereby the flow path substrate 1 was fabricated.

  Subsequently, as shown in FIG. 2G, the glass diaphragm material 6 a that has undergone the first heating step is anodically bonded to the flow path substrate 1. The glass vibrating plate material 6a was bonded to the surface corresponding to the pressure generation chamber 2 of the flow path substrate 1 so as to close the etching groove including the pressure generation chamber 2, the nozzle 3, the orifice 4, and the like. In the anodic bonding process of the present embodiment, the bonded surfaces of the flow path substrate 1 and the glass diaphragm material 6a are cleaned and overlapped, heated to 350 ° C., and the flow between the glass diaphragm material 6a and the flow path substrate 1 is increased. A voltage of 200 V was applied using the road substrate 1 side as an anode, and further pressed.

  Subsequently, as shown in FIG. 2 (h), the glass diaphragm material 6a bonded to the flow path substrate 1 was polished and thinned to a thickness of 5 μm to form the diaphragm 6. This thinning process was performed by polishing using a lapping machine and an abrasive, and was flattened by removing irregularities and undulations. Further, during polishing, the abrasive particle size was made minute in steps, and finally the polished surface was mirror-finished using colloidal silica.

Subsequently, as shown in FIG. 2I, the lower electrode 9a and the piezoelectric precursor layer 8a were directly formed and laminated on the vibration plate 6. The lower electrode 9a was formed by sequentially stacking Ti by 20 nm and Pt by 150 nm by a sputtering method. As the piezoelectric precursor layer 8a, a thin film of PZT (lead zirconate titanate) precursor having a thickness of 3 μm was formed by a high frequency sputtering method. The film formation conditions of the piezoelectric precursor layer 8a were a PZT sintered body in which PbO was added excessively by 10% as a target, and a material in which 10% O ₂ was added to Ar as a sputtering gas, a total pressure of 2 Pa, and a substrate temperature of 200. ° C., and the high frequency output was 4W / cm ² applied to the target. By doing in this way, the piezoelectric precursor layer 8a containing the metal component of Pb, Zr, Ti, and oxygen with the composition ratio reflecting the composition of the target was obtained.

  Subsequently, as shown in FIG. 2J, a second heating step was performed to crystallize the piezoelectric precursor layer 8a. The second heating step was performed using an electric furnace in an oxidizing atmosphere with a maximum heating temperature of 650 ° C. and a heating time of 5 hours, and then cooled to room temperature. In this way, the piezoelectric precursor layer 8a was crystallized to form the piezoelectric layer 8. The piezoelectric layer 8 after the second heating step was a PZT thin film having good crystallinity as evaluated by an X-ray diffraction method.

  In the present embodiment, the piezoelectric precursor layer 8a is formed and then crystallized by performing the second heating process. However, in the process shown in FIG. Good.

  Subsequently, an upper electrode 9b was formed as shown in FIG. The manufacturing method of the upper electrode 9b was the same as that of the lower electrode 9a.

  Subsequently, as shown in FIG. 2 (l), the upper electrode 9b, the piezoelectric layer 8, and the lower electrode 9a were sequentially processed by photolithography and etching to produce the piezoelectric element 7. The piezoelectric element 7 is provided at a position corresponding to each pressure generating chamber 2 on the vibration plate 6. The upper electrode 9b and the lower electrode 9a were etched by dry etching using Ar gas using a photoresist as a mask. Etching of the piezoelectric layer 8 was performed by wet etching with an etching solution in which a hydrofluoric acid aqueous solution and a nitric acid aqueous solution were appropriately mixed using a photoresist as a mask.

  Subsequently, as shown in FIG. 2 (m), the diaphragm 6 and the flow path substrate 1 were cut at an intermediate position of the nozzle 3, and the nozzle 3 was opened. A dicing saw was used for the cutting process. In this step, a resin bonded # 1500 diamond blade with a thickness of 0.2 mm was used as a cutting blade, and a cutting speed of 0.5 mm / sec. Full cut.

  The liquid discharge head manufactured by the manufacturing method comprising the above steps performed a good liquid discharge operation such as ink by applying an appropriate driving voltage to the piezoelectric element. Further, neither deformation of the flow path substrate nor generation of cracks in the glass diaphragm was observed.

  As described above, according to the manufacturing method of the liquid discharge head of the present embodiment, the piezoelectric elements are directly formed on the glass diaphragm, and the liquid discharge head with high discharge efficiency is manufactured by arranging the nozzles at high density with high yield. I was able to.

  In this example, the step of determining the temperature condition of the first heating step of pre-shrinking the glass diaphragm material so that the thermal contraction rate of the diaphragm in the second heating step is 0.01% or less, A first heating step of pre-shrinking the glass diaphragm material under temperature conditions; a step of joining the glass diaphragm material that has undergone the first heating process to the pressure generating chamber by anodic bonding; and an electrode layer and a piezoelectric on the diaphragm A step of directly forming the layer and a second heating step of crystallizing the piezoelectric layer. A method for obtaining the temperature condition of the first heating step in this embodiment is shown in FIG.

First, as shown in FIG. 3A, a heat shrinkage measurement sample 16a having the same material, manufacturing process, and thermal history as the glass diaphragm material 6a of Example 1 was prepared. Since there is a variation in the glass material at the time of manufacture, even if the same heating step is performed, the thermal shrinkage rate may vary. Preferably, the thermal shrinkage rate measurement sample 16a is the same as the glass diaphragm material 6a. What was cut into the same shape from the plate material by the same method is used. That is, the heat shrinkage rate measurement sample 16a was made of HOYA trademark SD2 glass, like the glass diaphragm material 6a used in Example 1, and a plurality of squares with a thickness of 50 μm and a side of 50.00 mm were prepared. . The illustrated length L ₀ is obtained by measuring the length of one side of each of the thermal contraction rate measurement samples 16a using a laser length measuring machine in a temperature-controlled room with an air temperature of 25 ° C.

Subsequently, as shown in (b) of FIG. 3, performing a first heating process test at different temperature conditions for a plurality of thermal shrinkage measurement sample 16a, to measure the dimension L ₁ after the heating step test. The temperature condition in this step was performed in the range from room temperature to the strain point temperature of the heat shrinkage measurement sample 16a. The illustrated length L ₁ is obtained by measuring the length of one side of each of the thermal contraction rate measurement samples 16a using a laser length measuring machine in a constant temperature room at an air temperature of 25 ° C. after the first heating process test. It is.

Subsequently, as shown in FIG. 3 (c), the second heat-shrinkage measurement sample 16a subjected to the first heating process test under different temperature conditions is subjected to the second heating process under the second heating process condition. The heating process test was performed, and the dimension L ₂ after the heating process test was measured. In this embodiment, the second heating step is a temperature at which the piezoelectric precursor layer is crystallized, and an electric furnace is used and the maximum heating temperature is 650 ° C. and the heating time is 5 hours in an oxidizing atmosphere, and then cooled to room temperature. The second heating process test in this process was also performed on all the heat shrinkage measurement samples 16a under the same conditions. The length L ₂ shown in the figure is obtained by measuring the length of one side of each of the heat shrinkage measurement samples 16a using a laser length measuring machine in a constant temperature room at an air temperature of 25 ° C. after the second heating process test. It is.

From the dimension L ₁ and the dimension L _{2 in each of} the heat shrinkage measurement samples 16a that have undergone the above steps, the heat shrinkage rate C ₂ in the second heating step was determined by the following equation.

C ₂ = (L ₁ −L ₂ ) / L ₁
From the above data, when the temperature condition of the first heating step was determined such that the thermal contraction rate C ₂ of the diaphragm in the second heating step was 0.01% or less, the range of 630 to 670 ° C. Met.

  The first heating step was performed under the temperature conditions thus obtained, and a liquid discharge head was manufactured in the same manner as in Example 1.

  The liquid discharge head manufactured by the manufacturing method of this example performed a very good liquid discharge operation such as ink by applying an appropriate driving voltage to the piezoelectric element. Further, neither deformation of the flow path substrate nor generation of cracks in the glass diaphragm was observed.

  By obtaining the conditions of the first heating step for preliminarily shrinking so that the thermal contraction rate of the glass diaphragm in the second heating step is within a certain range, the first heating step is performed to obtain a liquid with higher yield. It became possible to manufacture a discharge head.

1 shows a liquid discharge head according to a first embodiment, where (a) is a schematic perspective view thereof, and (b) is a cross-sectional view taken along line AA of (a). FIG. FIG. 3 is a process diagram for explaining the manufacturing method of Example 1. It is a figure explaining the method of calculating | requiring the temperature condition of a 1st heating process in Example 2. FIG. It is a schematic cross section showing a liquid discharge head according to a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flow path board | substrate 2 Pressure generation chamber 3 Nozzle 4 Orifice 5 Liquid supply chamber 6 Diaphragm 7 Piezoelectric element 8 Piezoelectric layer 9a Lower electrode 9b Upper electrode

Claims (3)

A method of manufacturing a liquid discharge head that pressurizes a liquid in a pressure generating chamber by a piezoelectric element on a glass diaphragm and discharges the liquid from a nozzle.
Preparing a flow path substrate having a pressure generating chamber and a nozzle;
A first heating step of heating the glass diaphragm material to a predetermined temperature;
A bonding step of bonding the glass diaphragm material to the flow path substrate by anodic bonding;
Forming a piezoelectric element by sequentially laminating an electrode layer and a piezoelectric layer on a glass diaphragm made of a glass diaphragm material;
And a second heating step of heating the piezoelectric layer during or after being laminated on the glass diaphragm to a temperature for crystallization.   2. The method of manufacturing a liquid ejection head according to claim 1, further comprising a step of polishing and laminating the glass diaphragm material to form a glass diaphragm having a predetermined thickness between the bonding step and the forming step.   3. The liquid discharge head according to claim 1, wherein the temperature of the first heating step is set so that the thermal contraction rate of the glass diaphragm in the second heating step is 0.01% or less. Production method.

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