JP3168713B2 - Ink jet head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to the manufacture of printheads for ink jet printers.

[0002]

2. Description of the Related Art In recent years, print heads for ink-jet printers have been required to have precise fine processing and complicated desired shapes due to the demand for high-definition printing, and various manufacturing methods have been developed.

Therefore, as described in Japanese Patent Application Laid-Open No. 2-297445, production of an ink jet head using a Si wafer having a (110) plane orientation has been proposed. This is because a (110) -oriented Si wafer has a crystal axis of <211.
> When a linear pattern is formed along the axis and wet-crystal anisotropic etching is performed, (11
1) Since a crystal plane appears, grooves such as ink nozzles and ink pressure chambers having a very high aspect ratio can be formed, so that the pitch between nozzles can be easily narrowed, and an ink jet head having a high ink dot density can be manufactured. It is based on the idea.

However, a Si wafer having a (110) plane orientation has a (111) angle at an angle of 35 degrees with respect to the wafer surface from the intersection of two linear patterns along the <211> axis.
When a surface appears and the surface appears, the etching does not proceed any further. For this reason, the area of the diaphragm located below the ink pressurizing chamber in the through groove becomes smaller, and the driving voltage for ejecting ink becomes higher, and the required amount of liquid in the ink pressurizing chamber cannot be satisfied. It has become.

For this reason, the design of the ink jet head is greatly restricted.
0) An inkjet head using a Si wafer having a plane orientation has not been put to practical use.

[0006]

SUMMARY OF THE INVENTION The (110) plane orientation S
On the i-wafer, a (111) plane appears at an angle of 35 degrees with respect to the wafer surface from the intersection of the two linear patterns along the <211> axis. When the plane appears, the etching does not proceed any further. For this reason, it is not possible to form the shape freely, and therefore, there is a problem that it is not possible to manufacture an ink pressure chamber, a flow path, or the like composed only of the (111) crystal plane perpendicular to the wafer surface. Therefore, an ink jet head using a Si wafer having a (110) plane orientation has not been put to practical use.

Furthermore, in the photolithography process, the alignment accuracy of both surfaces has a mechanical error of at least about 5 μm of the exposure device, and this error is further increased by the crystal anisotropic etching, causing a large dimensional variation. Due to the dimensional variation, the ejection characteristics vary for each nozzle of the inkjet head having a large number of nozzles, and this has been an issue in recent years for manufacturing a high-density and high-definition inkjet head.

[0008]

According to the present invention, there is provided an ink jet head comprising an Si substrate, wherein an ink reservoir and a plurality of ink pressurizing chambers communicating with the ink reservoir through orifices are formed. One substrate, a second substrate disposed on one surface side of the first substrate, and formed with a plurality of piezoelectric elements corresponding to the plurality of ink pressurizing chambers, and the other surface of the first substrate And a third substrate having a plurality of ink ejection ports formed corresponding to the plurality of ink pressurizing chambers, wherein the side surfaces of the plurality of ink pressurizing chambers are ( 111) a crystal plane. In addition, S having a (110) plane orientation
an i-substrate, a first substrate in which an ink reservoir and a plurality of ink pressurizing chambers communicating with the ink reservoir via an orifice are formed; and a first substrate disposed on one surface side of the first substrate; A second substrate on which a plurality of piezoelectric elements are formed corresponding to the plurality of ink pressurizing chambers; and a second substrate disposed on the other surface side of the first substrate, the plurality of piezoelectric elements corresponding to the plurality of ink pressurizing chambers. And a third substrate having the ink discharge ports formed thereon, comprising: forming a mask pattern for forming the ink pressurizing chamber on the front and back surfaces of the first substrate; A method for manufacturing an ink jet head, wherein the ink pressurizing chamber is formed by etching. Preferably, the opening of the mask pattern formed on one of the front and back surfaces of the first substrate is
It is characterized in that it is smaller than the opening of the mask pattern formed on the other surface.

In the mask pattern of the opening of the ink pressurizing chamber in the through groove formed on the surface of the wafer, the dimension of the opening on one side of the wafer is smaller than the dimension of the opening on the other side by a certain value. By forming the mask pattern described above, the dimensional variation of the ink pressurizing chamber of the formed through groove can be extremely reduced.

[0010]

The operation of the present invention will be described. FIG. 2 shows a vertical (11) to the wafer surface according to one embodiment of the present invention.
1 is a diagram schematically illustrating the principle of forming an ink pressurizing chamber 14 of a through groove surrounded by a crystal plane.

The two sides of the wafer having the (110) plane orientation are formed along the <211> direction by photolithography as shown in FIG.
A mask pattern of the ink pressurizing chamber of the through groove as shown in (a) is formed, and etching is performed by wet crystal anisotropic etching until the Si wafer is penetrated. FIG. 2B is a cross-sectional view of the Si wafer immediately after penetration by wet-crystal anisotropic etching, and is indicated by a cross section taken along line AA in FIG. Immediately after the penetration, the (111) crystal plane 60 that appears at an inclination of 35 degrees with respect to the wafer surface is overhanging, so that the penetration is narrow.

Therefore, when the etching is further continued, the overhang portion is undercut 61 as shown in FIG.
It disappears steadily. Then, as shown in FIG. 2D, the undercut stops when it hits the vertical (111) crystal plane 62. As described above, by making good use of the undercut phenomenon, the vertical (111)
The ink pressure chamber 14 of the through groove surrounded by the crystal plane can be easily formed. In order to manufacture an ink jet head having a print density of 360 dots per inch, an ink pressurizing chamber having a width of 50 microns, a length of 3.5 mm, and a depth of 500 microns is required. As a result, it was found that the ink amount was 1.3 times larger and the diaphragm area was 1.7 times larger than the case where an ink pressurized chamber having a (111) crystal plane inclined at 35 degrees was formed.

According to the present invention, it is easier to manufacture an ink jet head having a better ink ejection characteristic and a lower driving voltage than ever, and also to manufacture a high definition and high print density ink jet head. .

Also, the opening dimension of the mask pattern of the ink pressurizing chamber 14 in the through groove is not made the same on both sides, but one of the pattern dimensions is made smaller by a specific value than the other. The desired dimensional accuracy after the crystal anisotropic etching is dramatically improved.

The principle will be described in detail. FIG. 3 is a diagram illustrating the principle according to one embodiment of the present invention.

When patterning on both sides of a Si wafer,
An error always occurs in the alignment between the back and front of the wafer.
Therefore, as shown in FIG. 3A, the mask size of the opening of the ink pressurizing chamber 14 in the through groove on the back side of the wafer is made smaller than the mask size of the opening on the front side by a specific value. In FIG. 3A, the mask pattern 17 on the front side of the ink pressurizing chamber is indicated by a solid line.
The mask pattern 13 on the back side of the ink pressurizing chamber is indicated by a broken line. FIG. 3B is a cross-sectional view taken along the line BB in FIG.

Next, when the Si wafer is wet-crystal anisotropically etched, vertical (111) crystal planes 62 appear along the front and back patterns as shown in FIG. 3C. Here, it was formed along the front and back patterns (11
1) The step 63 is formed because the position of the crystal plane 62 is shifted.

When the etching is further continued, a step portion is formed by the undercut phenomenon as shown in FIG. 3D, and the ink pressurizing chamber 14 having a through groove corresponding to the size of the front side mask having a large opening size is formed. Can be done.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments.

(Embodiment 1) FIG. 1 is a perspective view of an ink jet head according to a first embodiment of the present invention. The structure of the ink jet head will be described with reference to FIG.

The Si wafer 10 having a (110) plane orientation has an ink pressurizing chamber 14 in a through groove surrounded by a (111) crystal plane perpendicular to the wafer surface. The ink is filled by a shallow groove called an orifice 16. Is in communication with The ink reservoir 15 is constituted by a (111) crystal plane having an inclination of 35 with respect to the wafer surface.

Further, a nozzle plate 20 is joined to one side of the opening of the ink pressurizing chamber 14 in the through groove to form the ink ejection port 2.
1 communicates with the ink pressurizing chamber 14 in the through groove. Further, a thin diaphragm 300 is joined to the other opening of the ink pressurizing chamber 14 in the through groove, and the piezoelectric element 100 is bonded to the diaphragm 300. This piezoelectric element 10
Printing is performed by giving a signal current to 0.

FIG. 4 shows a process of manufacturing the ink jet head shown in FIG. The manufacturing method of the ink jet head will be described with reference to FIG.

First, a Si wafer 1 having a (110) plane orientation
0 is thermally oxidized to form a silicon oxide film 11 as an etching resistant mask material on the wafer surface as shown in FIG. In this embodiment, a silicon oxide film is used as an etching-resistant mask material, but a silicon nitride film, a silicon carbide film,
Any film, such as a metal film, that can withstand a Si alkaline etching solution or the like may be used, and is not limited to a silicon oxide film.

Next, a resist is applied to the Si wafer 10 by spin coating, and a resist mask pattern to be the orifice 16 is formed at a predetermined location on the wafer surface by photolithography. Is used to etch the silicon oxide film.
An orifice mask pattern 12 is formed as shown in FIG. Then, the unnecessary resist is removed by a resist stripper.

Then, S containing hydrofluoric acid and nitric acid as main components
Immersion in an isotropic etching solution for a predetermined time
6 is formed as shown in FIG.

The orifice-formed Si wafer is 1
By immersion in hydrofluoric acid, the silicon oxide film on the surface is removed, and a silicon oxide film having a thickness of 1 micron is provided on the entire surface of the Si wafer by thermal oxidation again as shown in FIG.

Subsequently, a resist is again applied to the Si wafer 10 by a spin coating method, and a resist mask pattern to be an ink pressurizing chamber 14 and an ink reservoir 15 of a through groove is formed on the surface of the orifice-formed wafer. After forming a resist mask pattern to be the ink pressurizing chamber 14 of the through groove on the back surface by using the photolithography technique, the silicon oxide film is etched with a buffered hydrofluoric acid solution, and as shown in FIG. An ink pressurizing chamber mask pattern 17, an ink reservoir mask pattern 18, and an ink pressurizing chamber mask pattern 13 on the back surface are formed.
Then, the unnecessary resist is removed by a resist stripper.

Thereafter, a 20% by weight aqueous solution of KOH is heated to 80 degrees Celsius, the Si wafer 10 is immersed, penetrated through the ink pressurizing chamber, and 35 wt.
Etching is performed until the (111) crystal plane having a degree of inclination disappears, and the ink pressurizing chamber 14 and the ink reservoir 15 of the through groove are formed as shown in FIG.

The ink pressurizing chamber 14 in the through groove, the orifice 1
6, and the Si wafer on which the ink reservoir 15 is formed is immersed in hydrofluoric acid once to remove the silicon oxide film on the surface, and then thermally oxidized again on the entire surface of the Si wafer to improve the wettability of the ink. 1. Apply a thin silicon oxide film of 1 micron.

Thereafter, the nozzle plate 20 and the Si wafer 10 were bonded.

Here, as described in page 86 of "Precision and fine processing of electronics" by Sogo Denshi Publishing Co., Ltd. (by Kiyotake Taruoka), the nozzle plate 20 is (100).
It was fabricated by performing photolithography and wet-crystal anisotropic etching on a plane-oriented Si wafer.

However, the nozzle plate 20 may be formed by punching a thin stainless steel plate with a YAG laser or the like, or by an electroforming method as described in JP-A-3-146652. It may be manufactured, and it is not limited to this embodiment.

Next, borosilicate glass to be the diaphragm 300 is electrostatically bonded to the Si wafer 10 and the diaphragm 3
The piezoelectric element 100 is bonded on the ink pressurizing chamber 14 in the through groove of No. 00 as shown in FIG. Finally, wiring is applied to each piezoelectric element, and the ink tube 200 is connected to a predetermined position to complete the ink jet head.

When a print signal of a driving frequency of 7 kHz was actually given to the piezoelectric element 100 of the completed ink jet head and printing was performed, very fine printing could be performed. The pitch between the ink nozzles of the ink jet head manufactured in this embodiment is 70 microns, which can be printed at a print density of 360 dots per inch.

(Example 2) Ten silicon wafers having a (110) plane orientation are thermally oxidized to form a silicon oxide film on the surface of the Si wafer. In this embodiment, a silicon oxide film is used as the etching resistant mask material.
Any film, such as a silicon carbide film or a metal film, that can withstand a Si alkaline etching solution or the like may be used, and is not limited to a silicon oxide film.

In order to form the ink pressurizing chambers 14 of the ink pressurizing chambers of 20 through grooves for each Si wafer, ink pressurizing chamber mask patterns 13 and 17 of the penetrating grooves are formed on both sides of the wafer. FIG. 5A is a view showing a part of a mask pattern of the ink pressurizing chamber in the through groove. In this figure, the mask pattern 17 on the front side is shown by a solid line, and the mask pattern 13 on the back side is shown by a broken line.

FIG. 5B is a sectional view taken along the line CC of FIG. 5A. Here, the opening dimension of the mask pattern on the front surface of the wafer is x1, and the opening dimension of the back surface of the wafer is x2.

Then, wet crystal anisotropic etching is performed, and the width x3 of the ink pressurizing chamber 14 of the through groove shown in FIG. 5C is measured. This x3 when the value of x2 is reduced
Table 1 shows the results obtained by examining the effect of this on dimensional variations.

[0040]

[Table 1]

The dimensional accuracy of the patterning of the silicon oxide film by photolithography is plus or minus 0.1.
2 microns.

According to Table 1, as the dimension x2 becomes smaller,
The standard deviation indicating the dimensional variation is small, and x2 is 47
Below a micron, a constant value of 0.8 is shown.

The value of x1-x2 is determined by
It may be different depending on the alignment accuracy of the aligner, but it is actually better to be larger than that.

In the case of a general aligner, the value of x1-x2 is preferably in the range of 2 to 100 microns.

When the value exceeds this range, for example, x1-x
When the value of 2 is smaller than 2 microns, the effect aimed at in this embodiment cannot be obtained, and the dimensional variation is not improved. If the value of x1−x2 is larger than 100 μm, the mask size is extremely different, so that the step portion generated during wet crystal anisotropic etching becomes large, and the time required for this to disappear is too long. Therefore, it is not preferable in production.

The alignment accuracy of the aligner used in this embodiment is plus or minus 2 microns. By reducing the dimension x2 beyond this value, the variation in the width of the ink pressurizing chamber of the through groove can be drastically reduced. I was able to.

Therefore, x1 = 50 microns, x2 = 47
An inkjet head formed with a photomask dimension of microns was manufactured according to Example 1, and when actually printed, very clear printing was obtained.

In addition, variations in the individual ink ejection characteristics of the plurality of ink nozzles have been improved, and high print quality without print unevenness can be easily obtained. This is because, in the related art, variations in the ink ejection characteristics of a plurality of ink nozzles are corrected by adjusting the drive voltage for each ink nozzle. Since the operation is omitted and the electronic circuit for the adjustment is not required, the production of the ink jet printer is further facilitated.

On the other hand, x1 = x2 = 5 shown in the comparative example
In the case of 0 μm, the average x3 of the width of the ink pressurizing chamber 14 in the through groove also becomes considerably large as 60 μm because of the undercut phenomenon, and its standard deviation becomes an extremely large value of 8.0. This indicates that the variation is large. Therefore, a high-density ink jet head having a plurality of nozzles with an ink dot density of 360 dots per inch requires an accuracy of ± 2 μm or more in the variation of the width of the ink pressurizing chamber 14 of the through groove. However, even if the ink pressurizing chambers of the through grooves were formed with the same dimensions on the front and back sides as in the comparative example, accuracy could not be obtained, and the ink ejection characteristics of each nozzle varied, and good print quality could not be obtained. .

Although the above embodiment has been described using the method of ejecting ink using a piezoelectric element, the present invention is not limited to this. Therefore, Japanese Patent Application No. 3-23
As described in Japanese Patent No. 4537, even if the ink pressurizing chamber 14 in the through groove is deformed by electrostatic attraction and repulsion to eject ink,
A heater may be formed inside the ink pressurizing chamber 14 in the through groove, and the ink may be heated directly to boil the ink to discharge the ink.

[0051]

As described above, the present invention has the following effects.

1) A mask pattern to be used as an ink pressurizing chamber is formed on both sides of a Si wafer having a (110) plane orientation,
By performing the wet crystal anisotropic etching, the ink pressurizing chamber of the through groove surrounded by the (111) crystal plane which appears perpendicular to the wafer surface can be formed very easily. A high-density multi-nozzle inkjet head using the ink pressurizing chamber in the groove was easily manufactured.

2) In the mask pattern of the opening of the ink pressurizing chamber in the through groove, the size of the opening on one side of the wafer is smaller than the size of the opening on the other side by a certain value. The dimensional accuracy of the ink pressurizing chamber in the through-groove of the inkjet head is greatly improved by forming the ink jet head, the variation in the individual ink ejection characteristics of the plurality of ink nozzles is improved, and high printing quality without printing unevenness is easily achieved. Now you can get it.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a structure of an inkjet head according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of a method for manufacturing an ink jet head according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a manufacturing process of the inkjet head according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating the principle of a method for manufacturing an inkjet head according to a second embodiment of the present invention.

FIG. 5 is a diagram for explaining dimensional positions of an ink jet head in Table 1 of Embodiment 2 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 (110) Orientation silicon wafer 11 Silicon oxide film 12 Orifice mask pattern 13 Back side ink pressurizing chamber mask pattern 14 Ink pressurizing chamber of penetration groove 15 Ink reservoir 16 Orifice 17 Front surface ink pressurizing chamber mask pattern 18 Ink reservoir mask pattern 20 Nozzle plate 21 Ink ejection port 60 Appears at an angle of 35 degrees with respect to the surface (1
11) Crystal plane 61 Undercut plane 62 Appearing perpendicular to the surface (111) Crystal plane 63 Stepped section 100 Piezoelectric element 200 Ink tube 300 Vibration plate

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shuji Oeda 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (56) References JP-A-3-253346 (JP, A) 54-150127 (JP, A) JP-A-4-125159 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/16

Claims (3)

(57) [Claims] A first substrate formed of a Si substrate and formed with an ink reservoir and a plurality of ink pressurizing chambers communicating with the ink reservoir via an orifice; and one of the first substrates. A second substrate, which is disposed on a surface side and on which a plurality of piezoelectric elements are formed corresponding to the plurality of ink pressurizing chambers; A third substrate formed with a plurality of ink ejection ports corresponding to the chambers, wherein the side faces of the plurality of ink pressurizing chambers are (111) crystal planes. Ink jet head. 2. An Si substrate having a (110) plane orientation,
A first reservoir formed with an ink reservoir and a plurality of ink pressurizing chambers communicating with the ink reservoir through an orifice;
A substrate, a second substrate disposed on one surface side of the first substrate, and formed with a plurality of piezoelectric elements corresponding to the plurality of ink pressurizing chambers, and a second surface side of the first substrate And a third substrate formed with a plurality of ink ejection ports corresponding to the plurality of ink pressurizing chambers. A method for manufacturing an ink jet head, comprising: forming a mask pattern for forming an ink pressurizing chamber; and then performing etching to form the ink pressurizing chamber. 3. The method according to claim 2, wherein the opening of the mask pattern formed on one surface of the front and back surfaces of the first substrate is smaller than the opening of the mask pattern formed on the other surface. The manufacturing method of the inkjet head according to the above.