JPH03297653A - Ink jet head - Google Patents

Abstract

PURPOSE:To obtain an ink jet head having characteristics such as high density, high nozzle number, and homogenuity at a low cost by a method wherein the title ink jet head is composed of a silicon substrate to which a thin film part is formed, a piezoelectric material formed to the thin film part of the silicon substrate, and a silicon substrate having a nozzle formed facing the thin film part of the silicon substrate. CONSTITUTION:To a piezoelectric material side substrate A1, a piezoelectric material 20' consisting of PZT as a vibrator and a thin film part 13 composed of a Si:B film 11 of a Si mono-crystalline substrate 10 are integrally in good precision respectively to a thickness of approx. 10mum not via a bonding process. The piezoelectric material side substrate A1 and a nozzle side substrate A2 are brought into a contact with each other so that a piezoelectric material layer 20 and a nozzle outlet 71 face outside. The piezoelectric material side substrate A1 is made to be of a minus potential and the nozzle side substrate A2 is made to be of a plus potential while they are being kept at 400 deg.C, 1000V in voltage is impressed between both, and they are bonded by an anode. Since the thin film part of the silicon substrate can be very extremely precisely formed thinly, the piezoelectric material can be made thin. Miniaturization of a cavity become capable of being performed, and high density and high nozzle number can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet head that selectively deposits ink droplets onto a recording medium.

[Conventional technology] As a conventional technology, as shown in FIG.
A plurality of ink cavities 420 are formed between 10 and a thin glass plate 411, and a plate of piezoelectric body 430 with electrodes 431 formed on both sides is cut to about the area of the ink cavities, and then a thin glass plate is placed on top of each ink cavity. There is an inkjet head that is sandwiched and glued together.

[Problem to be solved by the invention] Conventional inkjet heads use PZT, which is a material with the best piezoelectric effect, as a piezoelectric material, but because it is a product cut from a bulk, only a thick material of about 100 μm is used. I couldn't do that. Therefore, it is necessary to increase the drive voltage to 100 V or more, and since the mechanical displacement generating means consisting of the piezoelectric body 430 and the thin glass plate 411 has high rigidity, in order to obtain a predetermined amount of displacement, the piezoelectric body
It is necessary to increase the area of the head 30, which increases the size of the entire head, resulting in an increase in cost.

Furthermore, the width of the ink cavity 420 is several hundred μ on one side.
m, and a piezoelectric body 430 of the same size as these
Each ink cavity 42 uses a plate as a mechanical displacement generating means.
It was necessary to glue every 0. However, in a head with such a structure, the piezoelectric body 430 and the ink cavity 4
The piezoelectric body 430 cannot achieve high alignment accuracy with 20.
It had problems such as poor workability during bonding, large variations in properties due to non-uniformity of bonding, and large variations in properties due to internal strain during cutting process, which tends to cause peeling of the bonded part. .

These problems have become more prominent as the number of nozzles is increased or the nozzle density is increased in order to improve printer performance.

The present invention aims to solve these problems, and its purpose is to provide a highly reliable inkjet head with high density, a large number of nozzles, and uniform characteristics at an extremely low cost. .

[Means for Solving the Problems] An inkjet head of the present invention includes a silicon substrate on which a thin film portion is formed, a piezoelectric body formed on the thin film portion of the silicon substrate, and a piezoelectric body that faces the thin film portion of the silicon substrate. A silicon substrate having a nozzle formed therein.

[Function] According to the configuration of the present invention, since the substrate on which the piezoelectric body is formed is a silicon substrate, it is possible to form a thin film portion with extremely high precision.

With this, Nj! It becomes possible to use pzT, and it becomes possible to make the ink cavity smaller, which in turn makes it possible to make the head smaller. Furthermore, since the nozzle is also formed on the silicon substrate, deformation due to differences in thermal expansion coefficients can be suppressed even when the side substrates are bonded.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic perspective view of a printer using an inkjet head according to an embodiment of the present invention. 100 is an inkjet head, and 101 is its power line. 200
3 is a recording paper, and 300 is a platen. By rotating the platen 300 in the direction of arrow P in the figure, the recording paper 200
is sent in the direction of arrow M in the figure. At this time, the inkjet head 100 forms an ink image on the recording paper 200 while moving in the direction of arrow R in the figure.

The manufacturing method and structure of the piezoelectric substrate A1 of the inkjet head 100 will be described with reference to FIGS. 2 to 4.

In FIG. 2, 10 μm of S is doped with B as an impurity to one side of a double-sided polished Si single crystal substrate 10 with a thickness of 100 μm using a normal semiconductor process.
An isE film 11 is formed.

Next, using thermal oxidation, a Si○2 film 12 of 0.000. Form 1 μm. In this way, the Si single crystal substrate 10 is made of Si:B film 11.5102 film]2, Si
It has a three-layer structure of single crystal layers.

FIG. 3 is a state diagram of the piezoelectric body side substrate A1 in the next step, (a) is a top view, (b) is a sectional view taken along the line mm'' in the figure, and (c) is a bottom view.Sj: Pt, C on the B film 11
r, a common electrode layer 21 with a thickness of 1 μm made of Ni, etc., a piezoelectric layer 20 made of PZT with a thickness of 10 μm, Pt, '
Individual electrode layers 22 made of Cr, Ni, etc. are formed by sputtering or ion blasting. Then, a resist film 23 is formed on the individual electrode layer 22. The resist film 23 covers the vibrating body forming section 23-1 and the wiring forming section 23.
-2. The size of the vibrating body forming portion 23-1 is 42
The size is 5 μm x 800 μm, and the arrows in the figure indicate X-X'Y-
It is formed to have sides in the Y' direction. (Figure 3(a)). Further, SiO2 film 12 film 2 on single crystal substrate 1
The resist film 24 is formed so as to have sides in the direction of [110] of 0 (arrows x-x' and y-y' directions in the figure).
Figure 3 (C)).

FIG. 4 is a state diagram of the piezoelectric substrate A1 in the next step, in which (a) is a top view, (b) is a sectional view taken along line m-m' in the figure, and (C) is a bottom view. In the state shown in Figure 3,
Ion etching or reactive ion etching is performed using the pattern of the resist film 23 to form the common electrode layer 21.
, the individual electrode layer 22, and the piezoelectric layer 20 are etched, and the common electrode 21', the individual electrode 22', and the piezoelectric layer 20' are etched.
form. At the same time, the vibrating body section 26 and the wiring section 27 are formed.

Furthermore, using the pattern of the resist 24, SiO2i12
After removing the resist 24, the Si single crystal layer 14 of the Si single crystal substrate 10 is etched using a mixed solution of pyrocatechol, ethylenediamine, and water. Then, since the 5i02 film 12 has etching resistance, it is not etched, and only the portions where the film does not exist are etched. Then, every hour in the direction of [100] (arrow 2-2'' direction in the figure), [110] (arrow X-X'Y-Y' force direction in the figure, and [1111 (arrow Q-Q' direction in the figure)) Anisotropic etching is performed at speeds of 50 μm, 30 μm, and 3 μm to form a cavity 30, an ink supply path 4o, and an ink common path 50. At the same time, the Si bilayer film 1
One thin film portion 13 is formed.

The size of the cavity 30 is 600 μm in the vertical direction in the figure and 1000 μm in the horizontal direction in the figure. Also, due to anisotropic etching, the wall surface of the cavity 30 is tapered, and S
i; The size of the thin film portion 13 formed of the B film 11 is approximately 450 μm in the vertical direction in the figure and approximately 850 μm in the plate direction in the figure. The ink supply channels 40 are provided on both sides of the cavity 30 as shown in FIGS. 4(b) and 4(C), and have a triangular prism shape with a width of 30 μm, a depth of approximately 20 μm, and a length of 100 μm. are doing. The ink common path 50 has a width of 150 mm.
.mu.m and depth of 90 .mu.m, and a total of nine cavities are formed on both sides of the cavity 30. (See FIG. 5) The common ink path 50 also communicates with an ink tank (not shown).

The overall image of the piezoelectric side substrate A1 produced as described above will be explained using FIG. 5. FIG. 5 is an overall view of the piezoelectric substrate A1, in which (a) is a top view and (b) is a bottom view. The cavity 30 is shown vertically (300d p
i/8), that is, 8 at a pitch of approximately 677 μm.
pcs, also the horizontal position of the display cavity and the vertical position (
300dpi) In other words, with a shift of about 85μm, (300dpi)
d p i / 16) That is, a total of 64 cells are arranged in 8 rows at a pitch of about 1355 μm.

Next, the manufacturing process and structure of the nozzle side substrate A2 will be explained using FIGS. 6 to 9. In FIG. 6, reference numeral 60 denotes a Si single crystal substrate with a thickness of 100 μm which has been polished on both sides, and a 5i02 film 61 with a thickness of 0.1 μm is formed on both sides by thermal oxidation.

Furthermore, a resist layer 63 was formed on one side except for a square portion 64 of 180 μm x 180 μm so as to have sides in the direction of [110] (arrow v-v'w-w'' direction in the figure), and on the other side. (Fig. 7).

The SiO2i 61 in the square portion 64 is removed by etching, and then the resist layer 63 is also removed. continue,
A Si single crystal substrate 60 is anisotropically etched using a mixed solution of pyrocatechol, ethylenediamine, and water (FIG. 8). After this, the SiO2 film is also removed. In this way, a nozzle 70 with a lower outlet 1 of 40 μm×40 μm is formed (FIG. 9).

The arrangement of the formed nozzles 70 is the same as the arrangement of the cavities 30, and the number is 64.

The piezoelectric side substrate A1 and the nozzle side substrate A2 made as above are brought into contact with each other so that the piezoelectric layer 20 and the nozzle exit lower part 1 face outward, and while maintaining the temperature at 400°C, the piezoelectric side substrate A1 is set to a negative potential. The side substrate A2 is brought to a positive potential, and a voltage of 1000 cm is applied between the two to perform anodic bonding. A structural diagram of the inkjet head completed in this manner is shown in FIG. 1O. The individual electrodes 22 are each connected to a driving driver. As shown in FIG. 3, the cavity 30 has ink supply passages 40 on both sides, and the nozzle outlet lower 1 is located in the center of the cavity 30, so the ink flows smoothly. Furthermore, since the ink supply path 40 and the nozzle flow path are short, air bubbles can be easily discharged.

As described above, according to this embodiment, the piezoelectric body 20' made of PZT as a vibrating body and the Si single crystal substrate 1
5j of 0 = 10 thin film parts 13 each made of B film 11
It is as thin as micrometers and can be formed integrally and accurately without going through an adhesion process. In addition, since the nozzle side substrate A2 is also made of the same material as the piezoelectric side substrate A1 during and after bonding, deformation due to differences in thermal expansion coefficients does not occur, and from this point of view, it is possible to achieve high precision inkjet printing. The head can be configured.

By making the vibrating body thin, it becomes possible to obtain sufficient displacement in a small cavity with low voltage. Therefore, an extremely highly integrated, compact device that can be driven at low voltage.
Highly reliable inkjet heads can be provided at low prices.

Further, according to the embodiment, it is possible to shorten the ink supply path 40, and a highly reliable inkjet head with excellent discharge characteristics of bubbles and the like can be provided.

[Effects of the Invention] According to the present invention, the thin film portion of the silicon substrate on which the piezoelectric body is formed can be formed thin with extremely high precision, so that the piezoelectric body can be made thin. Therefore, it becomes possible to downsize the cavity, and it becomes possible to achieve high density and a high number of nozzles. Further, since the nozzle is also formed on a silicon substrate, deformation due to differences in thermal expansion coefficients is prevented, and a highly reliable inkjet head can be obtained.

[Brief explanation of drawings]

FIG. 1 is an overall perspective view of a printer using an inkjet head according to an embodiment of the present invention. 2 to 4 are diagrams showing the manufacturing process and structure of a piezoelectric side substrate of an inkjet head according to an embodiment of the present invention. FIG. 5 is a perspective view showing the overall structure of a piezoelectric side substrate of an inkjet head according to an embodiment of the present invention. 6 to 9 are diagrams showing the manufacturing process and structure of a nozzle side substrate of an inkjet head according to an embodiment of the present invention. FIG. 10 is a diagram showing the structure of an inkjet head according to an embodiment of the present invention. FIG. 11 is a diagram showing a conventional example. 00 00 00 0 1 2 Inkjet head recording paper platen Si single crystal substrate Si: B film SiO2 film 11- 12- 3 0 20' 6 7 0 0 0 0 0 10 20 30 Thin film part piezoelectric layer piezoelectric vibrating body wiring Cavity Ink supply path Ink common path Si single crystal substrate Nozzle Glass substrate Ink cavity Piezoelectric material and above

Claims (1)

[Claims] An inkjet head that selectively deposits ink droplets onto a recording medium, the head comprising: a silicon substrate on which a thin film portion is formed; a piezoelectric body formed on the thin film portion of the silicon substrate; and a piezoelectric body facing the thin film portion of the silicon substrate. 1. An inkjet head comprising: a silicon substrate having nozzles formed therein;