JPH04241955A - Preparation of ink jet recording head - Google Patents

Abstract

PURPOSE:To prevent the surface contamination of a head due to the emission of ink and to uniformize the length accuracy of a channel part and the shape of a communication part in an ink jet recording head. CONSTITUTION:In the preparation of an ink jet recording head constituted by bonding a heater substrate to a channel substrate 10 having the connection part connecting channel part 1 and an ink reservoir part 2, each of the channel parts 1 is formed by anisotropic etching using an etching mask 4 as shown by Fig (A) and not only the corner of the apex of each of the channel parts is removed as shown by Fig (B) but also each of the channel parts is processed so as to have a curved surface by isotropic etching.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an ink jet recording head.

0002

[Prior art] Silicon anisotropic etching technology is
111} This method takes advantage of the fact that the etching rate of crystal planes is very slow compared to the etching rate of other crystal planes.
When using a silicon substrate having a (100) crystal plane on its surface, a square or rectangular pattern can be formed with great precision.

[0003] Conventionally, there is an example of applying this anisotropic etching of silicon to the formation of an ink flow path portion of an ink jet recording head.

For example, Japanese Patent Laid-Open No. 61-230954 describes a method for manufacturing an ink jet recording head. FIG. 9A is a perspective view of a channel substrate 10 on which an etching mask 4 for forming a channel portion 1 and an ink reservoir portion 2 is formed. By performing anisotropic etching of silicon using this etching mask 4, a channel portion 1 and an ink reservoir portion 2 are manufactured as shown in the plan view of FIG. 9(B).

In anisotropic etching, etching progresses to the correct shape only when the etching pattern shape is rectangular, so the channel portion 1 and the ink reservoir portion 2 are formed separately. Therefore, it is necessary to form a passage connecting the two. In this technique, for the ink supply port and the channel serving as the ink flow path, the connecting groove 3 is formed by dicing in the hatched portion in FIG. 9(B). Figure 9(C) is
It is a cross-sectional view of the same, and the parts similarly shown by hatching,
That is, a connecting groove 3 is formed between the channel portion 1 and the ink reservoir portion 2 using a dicing saw.

This channel substrate 10 is shown in FIG. 10(A).
As shown in FIG. 2, an inkjet recording head is manufactured by bonding a heater and a heater substrate 11 having electrodes for energizing the heater with an adhesive layer 12, and dividing the heater into individual heads using a dicing saw.

[0007] Furthermore, JP-A-2-111696 describes a method for forming an ink reservoir portion and a channel portion with high precision by providing a plurality of etching opening patterns on one surface and performing a plurality of etching steps. ing.

According to these conventional methods, during etching, the step of penetrating the substrate as the ink reservoir section and the step of forming the channel section, which requires high precision, are performed in separate steps.

However, when a silicon substrate with a (100) crystal plane is anisotropically etched, the cross section of the channel portion formed in the channel substrate is limited to a V-shape.
When attached to the heater substrate, which is a flat substrate, the cross-sectional shape of the nozzle is limited to a triangle.

[0010] When a nozzle with a triangular cross section is used, for example,
As shown in FIG. 10B, during ink ejection, ink tends to flow out from the apex of the triangular nozzle as indicated by 7. In addition, there is a problem in that fine ink scatters from the sides of the triangle, as shown by 8, and this is combined with the scattering from adjacent nozzles to stain the surface of the head.

Furthermore, since the shape is determined by the crystal orientation, if you want to increase the cross-sectional area of the nozzle, the only way is to widen the base, which is disadvantageous from the viewpoint of high density.

On the other hand, when isotropic etching is used to make a non-triangular nozzle, the channel portion 1 formed by etching from the opening of the etching mask 4 on the surface of the channel substrate 10 is , the cross section becomes nearly elliptical, but the end of etching can only be done by controlling the time, and the amount of etching is large, making it difficult to obtain uniform precision.

As mentioned above, the ink reservoir section and the channel section are not connected during etching, and are shown in FIG.
), (C), after the etching is completed, the ink reservoir part 2 and the channel part 1 are connected by digging a connecting groove 3 with a dicing saw, etc., and the ink is transferred from the ink reservoir part 2 to the channel part 1. We are trying to supply them with the following.

[0014] Connection is not limited to digging a connection groove with a dicing saw or the like, but it is also possible to connect by etching the connecting portion at the same time as etching. In this case, if etching is performed using an etching mask 4 with a pattern in which the channel portion and the ink reservoir portion are simply connected, as shown in FIG. As a result, etching progresses at the connection part, and due to a slight difference in etching conditions, as seen in the difference between L1 and L2 shown in FIG. 12(B), etching progresses to the partition wall of the channel part. There is a problem in that adjacent channel portions are connected at some portions and the lengths of the channel portions change. Therefore, there is a problem in that it is very difficult to manage the temperature, concentration, etching time, etc. of the etching solution.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to prevent staining of the head surface due to ink leakage and ink scattering during ink ejection, and to improve the direction of ink ejection. The purpose is to improve stability.

Another object of the present invention is to improve the accuracy of the length of the channel portion and to make the shape of the connecting portion uniform when the connection between the ink reservoir portion and the channel portion is formed by etching.

[0017]

[Means for Solving the Problems] The present invention provides an inkjet recording head manufactured by bonding a channel substrate having a connecting portion connecting a channel portion and an ink reservoir portion, and a heater substrate having a heater and a current-carrying electrode. In the method, in the invention of claim 1, the channel portion uses a silicon substrate whose surface is a (100) crystal plane, and after performing anisotropic etching, corners of the vertices are removed by isotropic etching. In addition, the channel portion is characterized in that it is formed by making the inside of the channel a curved surface.
This is characterized in that the etching mask is etched with a pattern having small protrusions at the connecting portions of the etching mask so that adjacent channel portions are not connected.

[0018] The channel part and the ink reservoir part are
It can be manufactured by performing anisotropic etching multiple times using different etching masks.

[0019]

[Operation] The invention according to claim 1 provides a channel substrate having a connecting portion connecting the channel portion and the ink reservoir portion;
In a method for manufacturing an inkjet recording head in which a heater and a heater substrate having a current-carrying electrode are bonded together, the channel portion is formed by anisotropic etching using a silicon substrate whose surface is a (100) crystal plane. Anisotropic etching is performed until the cross section is surrounded by {111} planes to form a V-shaped groove or a trapezoidal groove by controlling time, and in this etching, the amount of etching can be controlled with high precision. Then, by isotropic etching, the corners of the vertices are cut down and the inside of the channel portion is made into a curved surface. Since the amount of etching by isotropic etching may be small, the accuracy of the channel portion can be sufficiently guaranteed.

[0020] In a method for manufacturing an inkjet recording head in which a channel substrate having a connecting portion connecting a channel portion and an ink reservoir portion and a heater substrate having a heater and a current-carrying electrode are bonded, the channel portion and the ink reservoir portion are connected to each other. When the connection part is etched using an etching mask with a pattern in which the parts corresponding to the channel part and the ink reservoir part are simply connected, {11
1} planes, etching progresses at the connecting part, and due to slight differences in etching conditions,
As explained in B), the length of the channel section cannot be made constant.

Therefore, the invention according to claim 2 uses a pattern having small protrusions in the connecting portion of the etching mask. Then, when etching the channel portion after etching the ink reservoir portion, the portion under the small protrusion is also etched, so that the etching does not progress to the extent that adjacent channel portions are connected.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view across a channel portion for explaining a method of forming a channel portion and an ink reservoir portion by an anisotropic etching method in a method of manufacturing an ink jet recording head. In the figure, 1 is a channel portion, 4 is an etching mask, and 10 is a channel substrate.

For the channel substrate 10, a silicon substrate having a (100) crystal plane on the surface is used. After forming a Si3N4 film on the silicon substrate by CVD, patterning is performed by a photolithography process, and Si is etched by a dry etching method.
3 Etch the N4 film to form an etching mask 4. On the back surface of the channel substrate 10, an unpatterned Si3 N4 film remains on the entire surface.

Next, the process moves to anisotropic etching. First, a first etching process is performed using a heated KOH aqueous solution and an etching mask 4 of the Si3 N4 film to form a channel part and an ink reservoir part. At this time, the etching ends when the ink reservoir part penetrates the silicon substrate, but the etching ends at the point where the ink reservoir part penetrates the silicon substrate.
111} planes, etching is almost stopped and formation can be performed with high precision. A cross section in this state is shown in FIG. 1(A).

In the second etching step, isotropic etching is performed. As shown in FIG. 1(A), after forming the channel portion 1 into a V-shaped groove by anisotropic etching, HF, HNO3, CH3C were used as the etching solution.
Isotropic etching is performed using an OOH mixture. As a result, as shown in FIG. 1(B), although V-shaped traces remain, a groove surrounded by a curved surface can be formed.

After the etching is completed, the Si3 N4 film is
Remove with phosphoric acid heated to 180°C. After that, the channel part and the ink reservoir part are connected.

The channel substrate 10 produced as described above and the heater substrate 11 on which heating elements are formed at positions corresponding to the respective channels are bonded together as explained in FIG. FIG. 2 shows an example in which discharge ports are formed. As can be seen by comparing with FIG. 10(B), the ink outflow 7 to the apex of the triangle that occurs during printing is reduced;
Further, the amount of dirt on the head surface caused by fine ink scattering 8 generated during ink ejection is reduced. Therefore, ink stains between adjacent nozzles become difficult to connect. As a result, ink contamination around the nozzle was reduced, and directional stability during ink ejection was extremely high.

FIG. 3 is a sectional view of a channel substrate for explaining another embodiment of the present invention. In this example,
The present invention is applied to a method in which the anisotropic etching step is performed in two steps. In the figure, 1 is the channel part,
2 is an ink reservoir part, 5 is an etching mask for Si3N4 film, 6 is an etching mask for SiO2 film, 1
0 is a channel substrate. By performing the anisotropic etching in two steps, the channel portion can be etched in the minimum necessary time, and a highly accurate channel substrate with little variation can be created.

As shown in FIG. 3A, SiO2 is deposited on the channel substrate 10, which is a silicon substrate, by thermal oxidation.
A film is formed, and an etching mask 6 is formed which is patterned to exclude the channel portion 1 and the ink reservoir portion 2 by a photolithography process. Next, by CVD method, Si
3N4 film is formed, and an etching mask 5 is formed which is patterned to exclude only the ink reservoir portion 2 by a photolithography process.

In this way, Si3 N4 film, SiO2
Using etching masks 5 and 6 formed of two layers of films, the first anisotropic etching is performed using heated KOH.
The ink reservoir portion 2 is formed by using an aqueous solution. Next, using phosphoric acid heated to 180°C, Si3N4
After removing the film, the channel portion 1 is etched by a second anisotropic etching using an etching mask of the SiO2 film, as shown in FIG. 3(B). At this time, if etching is performed until the {111} crystal plane of silicon is completely exposed, the channel portion can be formed as a V-shaped groove as shown in FIG. 1A, as in the previous embodiment.

Furthermore, in this state, HF, HNO3, C
Isotropic etching is performed as described above using a mixture of H3 COOH. As a result, a channel portion 1 surrounded by a curved surface can be formed as shown in FIG. 1(B).

FIG. 4 is a cross-sectional view of a channel section for explaining still another embodiment of the present invention. In the figure, parts similar to those in FIG. 1 are denoted by the same reference numerals, and explanations thereof will be omitted. In this embodiment, in the second anisotropic etching described with reference to FIG. 3, the etching time is controlled so that the etching is stopped at a trapezoidal shape as shown in FIG. 4(A). Thereafter, by performing isotropic etching in the same manner as described above, the inner surface of the channel portion 1 can be curved as shown in FIG. 4(B).

FIG. 5 shows an ink discharge port formed by bonding the channel substrate 10 produced as described above to a heater substrate 11 on which heaters are formed at positions corresponding to the respective channels. Since the stage before isotropic etching is a trapezoid, there is no acute angle corresponding to the vertex of the triangle, and the cross section of the channel portion 1 can be formed into a more curved surface. Therefore, almost no ink leakage is observed, and ink splatter 8 is prevented. Moreover, since the ink stains are generated in the opposite direction to the bottom side, the connection of ink stains between adjacent areas is no longer observed. As a result, as in the previous example, staining of the head surface with ink could be prevented, and the stability of the ink ejection directionality was improved.

FIG. 6 is for explaining an embodiment of a method for forming a connecting portion between a channel portion and an ink reservoir portion in the method of manufacturing an ink jet recording head of the present invention. , is a perspective view, and FIG. 6(B) is a sectional view. In the figure, parts similar to those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

A silicon substrate having a (100) crystal plane on the surface is used as the channel substrate 10. A SiO2 film is formed thereon to a thickness of 5000 angstroms by thermal oxidation, and the channel portion 1 is formed by a photolithography process. After patterning to remove the ink reservoir portion 2, the SiO2 film is etched by dry etching to form an etching mask 6. Next, C.V.
A Si3 N4 film is formed by the D method, and patterned by a photolithography process so that only the ink reservoir portion 2 is opened, thereby forming an etching mask 5. The back side of the substrate is an unpatterned SiO2 film, Si3 N4
The film remains.

After forming the two patterns using separate etching masks as described above, the process moves to anisotropic etching.

First, as shown in FIG. 6(B), Si3
Using the N4 film etching mask 5, a first etching process for forming the ink reservoir portion 2 is performed with a KOH aqueous solution heated to 90°C. Next, the Si3 N4 film was removed using phosphoric acid heated to 180°C, and this time the Si
A second etching step for forming the channel portion 1 is performed with a KOH aqueous solution heated to 90° C. using the O2 film etching mask 6. Finally, add SiO2 with hydrofluoric acid.
The film is removed to complete the channel substrate 10 on which the channel portion 1 and the ink reservoir portion 2 are formed.

This embodiment is characterized by the pattern of the etching mask 6 made of the SiO2 film in the above etching process. That is, as shown in FIG. 7, a pattern is used in which a small protrusion 9 is provided at a position protruding into the ink reservoir from a portion corresponding to the partition wall of the channel portion. In this example, the size of the small protrusions was 10 μm on one side.

By providing the small protrusions 9, the small protrusions are etched during the second etching step, which takes approximately 30 minutes to form the channel portion 1, as shown in FIG. 12(B). As described above, etching can be prevented from progressing until it connects with adjacent channels. Therefore, the length L1 of the channel portion can be formed with constant precision.

FIG. 8 shows S in the above etching process.
FIG. 7 is a plan view for explaining another example of the etching mask 6 made of an iO2 film.

In this embodiment, unlike FIG. 7, the small protrusions 9 of the etching mask 6 are provided in the width direction of the channel portion 1. Also in this embodiment, the portion remaining under the small protrusion 9 is etched within the time of the second etching process, thereby preventing connection with the adjacent channel portion.

The shape and size of the small projections 9 described above vary depending on the etching conditions and the distance between adjacent channels, but they must have a minimum size that does not connect adjacent channels.

[0043]

[Effects of the Invention] As is clear from the above description, according to the invention as claimed in claim 1, it is possible to prevent ink from flowing out from the apex of the nozzle, and to prevent contamination caused by fine ink scattering that connects and spreads between adjacent nozzles. It is possible to obtain an inkjet recording head in which the area can be narrowed, the influence of dirt on the ink ejection direction is small, and the ejection direction of ink droplets is stable. Furthermore, compared to a triangular nozzle made by anisotropic etching, even with the same length of the base, the cross-sectional area can be larger and the precision is better, which is advantageous for higher density.

In the second aspect of the invention, since the connecting portion between the channel portion and the ink reservoir portion can be formed by etching, there is no need for a step of connecting the channel portion and the ink reservoir portion using a dicing saw or the like. In addition, by providing small protrusions on the etching mask, adjacent channels are not connected.
Therefore, there is an effect that a channel portion having a uniform length can be formed by etching with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a channel portion for explaining an embodiment of the method for manufacturing an inkjet recording head of the present invention.

FIG. 2 is an explanatory diagram of a heater substrate bonded to the channel substrate of FIG. 1;

FIG. 3 is a cross-sectional view of a channel substrate for explaining another embodiment of the present invention.

FIG. 4 is a sectional view of a channel portion for explaining still another embodiment of the present invention.

FIG. 5 is an explanatory diagram of a heater substrate bonded to the channel substrate of FIG. 4;

FIG. 6 is an explanatory diagram of a method of forming a connecting portion between a channel portion and an ink reservoir portion in an embodiment of the present invention.

FIG. 7 is a plan view of an etching mask in one embodiment of the present invention.

FIG. 8 is a plan view of an etching mask in another embodiment of the present invention.

FIG. 9 is an explanatory diagram of a method for manufacturing a channel substrate in a conventional inkjet recording head.

FIG. 10 is an explanatory diagram of a conventional inkjet recording head.

FIG. 11 is a cross-sectional view of a channel substrate created by isotropic etching.

FIG. 12 is an explanatory diagram of a conventional method of forming a connecting portion between a channel portion and an ink reservoir portion.

[Explanation of symbols]

1 Channel part 2 Ink reservoir part 4 Etching mask 5 Si3 N4 film etching mask 6 Si
O2 film etching mask 10 Channel substrate

Claims (2)

[Claims] 1. A method for manufacturing an inkjet recording head in which a channel substrate having a connecting portion connecting a channel portion and an ink reservoir portion, and a heater substrate having a heater and a current-carrying electrode are bonded, wherein the channel portion comprises: (100) It is characterized by using a silicon substrate whose crystal plane is the surface, performing anisotropic etching, and then isotropic etching to reduce the corners of the vertices and to make the inside of the channel a curved surface. A method for manufacturing an inkjet recording head. 2. A method for manufacturing an inkjet recording head in which a channel substrate having a connecting portion connecting a channel portion and an ink reservoir portion, and a heater substrate having a heater and a current-carrying electrode are bonded to each other, wherein the channel portion comprises: A method for manufacturing an inkjet recording head, characterized in that etching is performed using a pattern having small protrusions in connecting portions of an etching mask so that adjacent channel portions are not connected.