WO2016158917A1

WO2016158917A1 - Method for manufacturing liquid ejection head nozzle plate, liquid ejection head nozzle plate, and liquid ejection head

Info

Publication number: WO2016158917A1
Application number: PCT/JP2016/060046
Authority: WO
Inventors: 洋明香西
Original assignee: コニカミノルタ株式会社
Priority date: 2015-03-30
Filing date: 2016-03-29
Publication date: 2016-10-06
Also published as: JPWO2016158917A1

Abstract

The present invention addresses the problem of providing a method for manufacturing a liquid ejection head nozzle plate with which stable injection performance can be obtained with high processing accuracy, and which has good nozzle bubble breaking properties. The present invention pertains to a method for manufacturing a liquid ejection head nozzle plate 21, the method for manufacturing the liquid ejection head nozzle plate 21 comprising the use of anisotropic etching to provide, in a Si substrate, a nozzle hole 211 having a small-diameter part 212 opening at one surface of the Si substrate, and a large-diameter part 213 larger than the small-diameter part 212 and opening at the other surface thereof from a communication hole 212a communicating with the small-diameter part 212. If the large-diameter part 213 has a top layer 213t contacting the other surface and a bottom layer 213b contacting the communication port 212a, the method is characterized by including a step of forming the top layer 213t with an average scallop width Wt and a step of forming the bottom layer 213b with an average scallop width Wb, wherein the following formula (1) is satisfied: Formula (1): Wt > Wb.

Description

Method for manufacturing nozzle plate for liquid discharge head, nozzle plate for liquid discharge head, and liquid discharge head

The present invention relates to a method for manufacturing a nozzle plate for a liquid discharge head, a nozzle plate for a liquid discharge head, and a liquid discharge head.

In recent years, inkjet printers are required to print at high speed and high resolution. As a method for manufacturing the components of the ink jet recording head used in this printer, there is a method using a semiconductor process for a silicon substrate or the like, which is a fine processing technique in the micromachine field. As one of the components of such an ink jet recording head, there is a nozzle plate, and a nozzle hole for discharging droplets (a through hole having one discharge opening as an opening) is formed by etching a silicon substrate. It is known to be a thing.

As a method of performing highly selective etching in the vertical direction (thickness direction) of a silicon substrate, an anisotropic etching method is known in which etching and sidewall protective film formation (deposition) are alternately switched. Yes.

The Bosch process is known as a technique for forming deep grooves in silicon by such an anisotropic etching method. In the Bosch process, holes are formed by performing etching by repeating an etching step and a deposition step. It is known that the side wall of the formed hole has a corrugated shape as seen on the surface of a scallop shell called scallop.

As a method of manufacturing a nozzle plate by the Bosch process, for example, a method of forming nozzle holes using an ICP (Inductively Coupled Plasma) type RIE (Reactive Ion Etching) apparatus is known (see Patent Document 1).

Also, there is provided a method for manufacturing a nozzle plate for a liquid discharge head, wherein a nozzle hole having a small diameter portion opened on one surface and a large diameter portion communicating with the small diameter portion and larger than the small diameter portion opened on the other surface is provided. Are known. For example, by setting the etching depth D and the diameter R of the opening of the etching mask pattern for forming the small diameter portion, by optimizing the etching processing conditions so that “D ≦ 0.1 × R”, A manufacturing method of a nozzle plate is disclosed in which the opening shape of the discharge port of the nozzle hole can be formed faithfully to the etching mask pattern (see Patent Document 2).

JP 2005-144571 A International Publication No. 2008/155986

By the way, since the high precision is normally required for the small diameter portion of the nozzle hole, when the nozzle plate is manufactured by the conventional Bosch process as described in

Patent Document

1 or 2, the scallop width is narrowed to achieve high precision. Etching is performed. On the other hand, the large-diameter portion of the nozzle hole is manufactured with a higher scallop width and higher etching rate because the required accuracy is lower than that of the smaller-diameter portion and the processing area is wide.

Therefore, the inventors have found that when a large diameter portion with a wide scallop width is formed on the nozzle plate by a nozzle plate manufacturing method using a conventional Bosch process, missing nozzles and injection blur are likely to occur. . This is because a wide scallop is likely to become small due to the trapping of fine bubbles, so that when the enlarged bubbles flow, it is difficult for the bubbles to escape from the nozzle holes, and there is no missing nozzle or injection blurring. This is probably because of the cause.

Also, in the manufacturing method of the nozzle plate by the Bosch process, it is thought that if the scallop width is made very small and the large diameter part is formed, the processing accuracy can be improved and the missing nozzle and injection blur can be improved. There is a problem that it takes time and costs.

The present invention has been made in view of the above problems, and the object of the present invention is to optimize the scallop width of the large-diameter portion, thereby obtaining a stable injection performance with high processing accuracy, and a nozzle. It is to provide a method for manufacturing a nozzle plate for a liquid discharge head, a liquid discharge head nozzle plate, and a liquid discharge head.

In order to solve the above problems, the invention described in claim 1
An anisotropic etching method that alternately repeats etching and formation of the sidewall protective film on the Si substrate, and opens from the communication port communicating with the small-diameter portion to the other surface through the small-diameter portion that opens to one surface, A method for producing a nozzle plate for a liquid discharge head, which is provided with a nozzle hole having a larger diameter portion than a smaller diameter portion,
When the large-diameter portion is a top layer in contact with the other surface, from the other surface to the communication port, a bottom layer in contact with the communication port,
Forming the top layer with an average scallop width Wt;
Forming the bottom layer with an average scallop width Wb;
And satisfying the following formula (1).
Formula (1): Wt> Wb

The invention according to claim 2 is the method of manufacturing a nozzle plate for a liquid discharge head according to claim 1,
When the middle layer between the top layer and the bottom layer,
Forming the middle layer with an average scallop width Wm;
The following formula (2) is satisfied.
Formula (2): Wt>Wb> Wm

According to a third aspect of the present invention, in the method for manufacturing a nozzle plate for a liquid discharge head according to the first or second aspect,
The anisotropic etching method is performed using a Bosch process.

Invention of Claim 4 is the manufacturing method of the nozzle plate for liquid discharge heads as described in any one of Claim 1- Claim 3,
The Si substrate includes a bonding layer made of a SiO ₂ layer having a low etching rate between two Si layers.

Invention of Claim 5 is the manufacturing method of the nozzle plate for liquid discharge heads as described in any one of Claim 1- Claim 4.
A liquid repellent layer is formed on the surface where the small diameter portion opens.

A sixth aspect of the present invention is the method of manufacturing a nozzle plate for a liquid discharge head according to the fifth aspect,
The thickness of the liquid repellent layer is in the range of 0.1 to 3.0 μm.

The invention described in claim 7
An anisotropic etching method that alternately repeats etching and formation of the sidewall protective film on the Si substrate, and opens from the communication port communicating with the small-diameter portion to the other surface through the small-diameter portion that opens to one surface, A nozzle plate for a liquid ejection head that has a nozzle hole having a larger diameter part than a smaller diameter part,
When the large-diameter portion is a top layer in contact with the other surface, from the other surface to the communication port, a bottom layer in contact with the communication port,
The average scallop width Wt of the top layer and the average scallop width Wb of the bottom layer satisfy the following formula (1).
Formula (1): Wt> Wb

The invention according to claim 8 is the nozzle plate for a liquid discharge head according to claim 7,
When the middle layer is formed between the top layer and the bottom layer, the average scallop width Wm of the middle layer satisfies the following formula (2).
Formula (2): Wt>Wb> Wm

The invention according to claim 9 is the nozzle plate for a liquid discharge head according to claim 7 or claim 8,
A liquid repellent layer is provided on the surface where the small diameter portion opens.

According to a tenth aspect of the present invention, in the nozzle plate for a liquid discharge head according to the ninth aspect,
The thickness of the liquid repellent layer is in the range of 0.1 to 3.0 μm.

The invention according to claim 11
A liquid discharge head comprising a head chip having the nozzle plate for a liquid discharge head according to any one of claims 7 to 10.

According to the present invention, it is possible to provide a method of manufacturing a nozzle plate for a liquid discharge head, a nozzle plate for a liquid discharge head, and a liquid discharge head, which have high nozzle bubble removal properties and stable ejection performance.

Exploded perspective view of inkjet head Cross section of head chip Schematic diagram for explaining the nozzle holes of the nozzle plate The figure which shows the nozzle plate of the initial state of the process of forming the large diameter part of a nozzle plate Diagram showing nozzle plate after applying photoresist The figure which shows the nozzle plate after forming the photoresist pattern The figure which shows the nozzle plate after forming the etching mask pattern Figure showing the nozzle plate after removing the photoresist pattern The figure which shows the nozzle plate which formed the top layer of the large diameter part The figure which shows the nozzle plate which formed the middle layer of the large diameter part The figure which shows the nozzle plate which formed the bottom layer of the large diameter part The figure which shows the nozzle plate which completed the formation process of a large diameter part The figure which shows the nozzle plate of the initial state of the process of forming the small diameter part of a nozzle plate Diagram showing nozzle plate after applying photoresist The figure which shows the nozzle plate after forming the photoresist pattern The figure which shows the nozzle plate after forming the etching mask pattern Figure showing the nozzle plate after removing the photoresist pattern The figure which shows the nozzle plate which formed the small diameter part The figure which shows the nozzle plate which the formation process of the small diameter part was completed

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

[Schematic configuration of inkjet head]
An ink jet head 1 as a liquid discharge head includes a head chip 2, a holding plate 3, a connection member 4, an ink flow path member 5, and the like (see FIG. 1 and the like).

The head chip 2 is configured by stacking and integrating three substrates of a nozzle plate 21, an intermediate plate 22, and a body plate 23 in order from the lower side.
The nozzle plate 21 is provided with nozzle holes 211 for ejecting ink.
The intermediate plate 22 is provided with a communication hole 221 that becomes an ink flow path when ink is ejected.

The body plate 23 includes a pressure chamber 231 filled with ink. The pressure chamber 231 includes an ink common channel 232 that is used for supplying or discharging ink, and ink passage ports 236 that open to the upper surface of the body plate 23 at both ends of the ink common channel 232.
Further, a piezoelectric element 234 as a pressure generating means is provided on the upper surface of the body plate 23, and the ink filled in the pressure chamber 231 inside the head chip 2 is pressurized by the displacement of the piezoelectric element 234, Ink droplets are ejected from the nozzle holes 211.

The holding plate 3 is bonded to the upper surface of the head chip 2 using an adhesive in order to maintain the strength of the head chip 2. The holding plate 3 has an opening 31 at the center, and the piezoelectric element 234 on the upper surface of the body plate 23 is configured to be stored inside the opening 31.
Further, in the vicinity of both end portions in the left-right direction of the holding plate 3, through

holes

32 and 32 that communicate the ink passage port 236 and the ink flow path member 5 are formed. The through holes 32 and 32 are used as ink flow paths that communicate between the ink

flow path members

5 and 5 and the head chip 2, respectively.

The connecting member 4 is a wiring member made of, for example, FPC, and the width direction of the connecting member 4 is bonded to the vicinity of the rear side of the upper surface of the holding plate 3 along the left-right direction of the holding plate 3 and is provided at the center of the holding plate 3. The piezoelectric element 234 is electrically connected through the opening 31. The connection member 4 is connected to a drive unit (not shown), and power can be supplied from the drive unit to the piezoelectric element 234 through the connection member 4.

One ink flow path member 5 is joined to each of both end portions of the upper surface of the holding plate 3 in the left-right direction, and an ink flow path port 51 for supplying and discharging ink is provided on the upper surface of the ink flow path member 5. . One of the two ink flow path members 5 may be used for supplying ink, the other may be used for discharging ink, and both may be used for supplying ink.
Further, it is preferable to provide a filter 52 for removing impurities such as dust and bubbles in the ink passing through the ink flow path member 5 inside the ink flow path member 5.
Hereinafter, the head chip 2 will be described in detail.

[Head chip]
The head chip 2 is configured by laminating and integrating three substrates of a nozzle plate 21, an intermediate plate 22, and a body plate 23 in order from the lower side (FIG. 2).

The nozzle plate 21 is made of, for example, a Si substrate having a thickness of about 100 to 300 μm, and the nozzle plate has a nozzle hole 211 penetrating in the vertical direction for ejecting droplets of ink or the like. The nozzle hole 211 is formed by a small-diameter portion 212 that opens on one surface, and a large-diameter portion 213 that communicates with the small-diameter portion 212 and opens on the other surface and is larger than the small-diameter portion 212.

The intermediate plate 22 is made of, for example, a glass substrate of about 100 to 300 μm, and penetrates the intermediate plate 22 at a position corresponding to the large-diameter portion 213 of the nozzle plate 21 so as to serve as an ink flow path when ink is ejected. Is formed.
The communication hole 221 adjusts the shape of the ink flow path, such as a shape that narrows the diameter of the path through which the ink passes, and adjusts the kinetic energy applied to the ink during ink ejection.
Further, as the glass substrate of the intermediate plate 22, borosilicate glass (for example, Tempax glass) is preferably used.

The body plate 23 is made of, for example, a Si substrate of about 100 to 300 μm, and includes a pressure chamber 231 that communicates with the communication hole 221 of the intermediate plate 22, an inlet 233 that individually supplies ink to the pressure chamber 231, and the body plate 23. An ink common channel 232 that supplies ink to each of the plurality of inlets 233 provided is formed.

On the upper surface of the pressure chamber 231, a vibration plate 235 that is thin and has a thickness of about 20 to 30 μm and is elastically deformable is formed. The vibration plate 235 vibrates in accordance with the operation of the piezoelectric element 234 provided on the upper surface of the vibration plate 235, and pressure can be applied to the ink in the pressure chamber 231.
Next, the nozzle plate 21 in the present invention will be described in detail.

[Nozzle plate]
The nozzle plate 21 is formed by an anisotropic etching method that alternately repeats etching and formation of a sidewall protective film, and a small diameter portion 212 that opens to the lower surface, and an upper surface from the communication port 212a that communicates with the small diameter portion 212. A nozzle hole 211 having a large diameter portion 213 larger than the small diameter portion 212 is formed (FIG. 3).
Note that the inner wall of the small diameter portion 212 and the large diameter portion 213 in FIG. 3 is schematically a scallop that can be seen because it is formed using anisotropic etching that repeatedly performs etching and formation of a sidewall protective film (deposition). Show.

The nozzle plate 21 is made of a Si substrate, and in particular, from the viewpoint of improving workability, it is preferable to use a so-called SOI wafer in which a bonding layer 21b made of a SiO ₂ layer is provided between two Si layers 21a. The coupling layer 21b is thinner than the Si layer (for example, 0.3 to 1.0 μm) and has a very low etching rate. Therefore, when the small diameter portion 212 and the large diameter portion 213 are each processed toward the bonding layer 21b, the processing can be controlled by the bonding layer 21b even when there is processing unevenness.

When the large-diameter portion 213 is a top layer 213t in contact with the upper surface from the upper surface to the communication port 212a, and a bottom layer 213b in contact with the communication port 212a, the average scallop width Wt of the top layer 213t, and the bottom layer The average scallop width Wb of 213b satisfies the following formula (1).
Formula (1): Wt> Wb

The “scallop width” in the present invention refers to the interval between the widths of the scallops per cycle when the repeating unit of alternately repeating etching and the formation of the sidewall protective film is one cycle in the anisotropic etching method. Say. Further, the “average scallop width” in the present invention means an average value of individual scallop widths.

By making the scallop width Wb of the bottom layer 213b close to the communication port 212a smaller than the scallop width Wt of the top layer 213t so as to satisfy the above formula (1), the smoothness of the side wall of the bottom layer 213b is improved, It is possible to make it difficult for bubbles to accumulate in the bottom layer 213b. Thereby, the foaming property of the nozzle is high, and stable injection performance can be obtained.

Further, when the middle layer 213m is formed between the top layer 213t and the bottom layer 213b, it is preferable that the average scallop width Wm of the middle layer 213m satisfies the following formula (2).
Formula (2): Wt>Wb> Wm

Thereby, since the smoothness of the side wall of the middle layer 213m is improved, it is considered that minute bubbles are hardly caught in the middle layer 213m. And it is thought that the bubble which generate | occur | produced in the large diameter part 213 becomes difficult to grow large, and it becomes difficult to generate | occur | produce the big bubble which block | closes the communicating port 212a.
Further, by accurately processing the middle layer 213m, which is the main pillar of the large diameter portion, so as to be perpendicular to the vertical direction, the influence of the processing error between the nozzle holes 211 provided in the nozzle plate 21 is minimized. It is possible to obtain a high injection performance in each nozzle hole 211 while limiting to the limit.

The ratio of the large diameter portions of the top layer 213t, middle layer 213m, and bottom layer 213b to the overall length in the vertical direction is within the range of 5 to 50% (for example, 20%) for the

top layer

213t, and 0 to 90 for the middle layer 213m. % (For example, 60%), the bottom layer is preferably in the range of 5 to 50% (for example, 20%), and the total of each is preferably 100%.
Here, the average scallop width Wt, the average scallop width Wm, and the average scallop width Wb are not particularly limited, but are preferably 2.5 μm or less, and 2.0 μm from the viewpoint of difficulty in catching bubbles. It is particularly preferred that

The small-diameter portion 212 is preferably formed with a thickness of 10 to 20 μm, for example, and the average scallop width is preferably 0.2 μm or less. Since the small-diameter portion 212 serves as an ejection port for ejecting droplets, the scallop width (etching width) is preferably narrowed and formed with high processing accuracy.

In addition, a liquid repellent layer 215 is preferably provided on the surface of the nozzle plate 21 where the small diameter portion 212 is opened. By providing the liquid repellent layer 215, it is possible to prevent the liquid ejected from the nozzle hole 211 from seeping out and spreading on the lower surface of the nozzle plate 21.
As the liquid repellent layer 215, a material having water repellency is used if the liquid ejected from the nozzle hole 211 is aqueous, and a material having oil repellency is used if the liquid ejected from the nozzle hole 211 is oily. . Specific examples include fluorine resins such as FEP (tetrafluoroethylene, hexafluoropropylene), PTFE (polytetrafluoroethylene), fluorosiloxane, fluoroalkylsilane, and amorphous perfluororesin. A film is formed on the lower surface of the nozzle plate by a known method such as vapor deposition. The thickness of the liquid repellent layer 215 is not particularly limited, but is preferably in the range of 0.1 to 3.0 μm.

[Nozzle plate manufacturing method]
An example of the nozzle plate manufacturing method will be described. In the nozzle plate manufacturing method described below, a method of forming the small diameter portion 212 after forming the large diameter portion 213 and removing the bonding layer 21b made of the SiO ₂ layer by a wet etching method using a diluted hydrofluoric acid solution. However, as long as the nozzle plate 21 described above can be manufactured, the manufacturing method can be selected as appropriate, and the present invention is not limited to the example shown below.
For example, the bonding layer 21b made of the SiO ₂ layer may be removed by a dry etching method, or the processing order may be reversed to form the large diameter portion 213 after forming the small diameter portion 212.

As a method for manufacturing the nozzle plate 21 of the present invention, a method for forming nozzle holes in a Si substrate will be described. In the nozzle hole 211 formed in the nozzle plate 21, the large diameter portion 213 is first formed from one surface of the nozzle plate (FIGS. 4A to I), and then the small diameter portion 212 is formed from the other surface of the nozzle plate ( Figures 5A-G).
In the following description of an example of the manufacturing method, the Bosch process is used as the anisotropic etching method, and the Si substrate for manufacturing the nozzle plate 21 is SiO ₂ between the two Si layers 21a. Although an SOI wafer provided with a bonding layer 21b made of layers is used, the present invention is not limited to this.

(Method for forming large diameter part)
As an Si substrate for manufacturing the nozzle plate 21, an SOI wafer provided with

thermal oxide films

216 and 217 made of SiO _{2 serving} as an etching mask on both surfaces is prepared (FIG. 4A).

Next, after applying a photoresist 218 to the surface of the thermal oxide film 217 on the side where the large-diameter portion 213 is to be formed (FIG. 4B), the photoresist 218 is applied to the surface other than the upper surface where the large-diameter portion 213 is to be formed. A photoresist pattern 218a is formed so as to achieve the above state (FIG. 4C). Next, a thermal oxide film pattern is formed by dry etching using, for example, CHF ₃ using the photoresist pattern 218a as an etching mask, and this is used as an etching mask pattern 217a in the anisotropic etching method (FIG. 4D).

After removing the photoresist pattern 218a (FIG. 4E), the etching condition and the deposition condition are set to the conditions that allow the etching with the average scallop width Wt by the anisotropic etching method in which the etching and the deposition are alternately repeated. The top layer 213t of the part 213 is formed (FIG. 4F).
Here, an ICP type RIE apparatus is preferable as an etching apparatus that performs the anisotropic etching method. For example, sulfur hexafluoride (SF ₆ ) is used as an etching gas during etching, and carbon fluoride is used as a deposition gas during deposition. Use (C ₄ F ₈ ) alternately.

Next, the etching conditions and the deposition conditions are changed to conditions that allow etching with the average scallop width Wm, and the middle layer 213m of the large diameter portion 213 is formed (FIG. 4G). Next, the etching conditions and the deposition conditions are changed to conditions that allow etching with the average scallop width Wb, and etching is performed until the bonding layer 21b is exposed, thereby forming the bottom layer 213b of the large-diameter portion 213 (FIG. 4H). Finally, the step of forming the large diameter portion 213 is completed by removing the etching mask pattern 217a (FIG. 4I).

As described above, the step of forming the large diameter portion 213 in the present invention includes the step of forming the top layer 213t with the average scallop width Wb, the step of forming the bottom layer 213b with the average scallop width Wb, and the middle layer 213m. Forming with an average scallop width Wm.
The average scallop widths Wt, Wm, and Wb described above satisfy at least the following formula (1), and preferably satisfy the following formula (2).
Formula (1): Wt> Wb
Formula (2): Wt>Wb> Wm

(Formation of small diameter part)
After the photoresist 219 is applied to the surface of the thermal oxide film 216 on the side where the small-diameter portion 212 is formed (FIG. 5B) on the Si substrate on which the large-diameter portion 213 is formed (FIG. 5A), the position where the small-diameter portion 212 is to be formed. A photoresist pattern 219a is formed so that a photoresist 219 is applied on the surface other than the top surface (FIG. 5C).
Next, a thermal oxide film pattern is formed using the photoresist pattern 219a as an etching mask, and this is used as an etching mask pattern 216a in the anisotropic etching method (FIG. 5D).

Next, after removing the photoresist pattern 219a (FIG. 5E), etching is performed until the bonding layer 21b is exposed by an anisotropic etching method in which etching and deposition are alternately repeated to form the small-diameter portion 212 (FIG. 5). 5F). Then, the step of immersing in a diluted hydrofluoric acid solution to remove the etching mask pattern 216a and the bonding layer 21b exposed on the surface and forming the small diameter portion 212 is completed (FIG. 5G).

[Others]
It should be thought that embodiment disclosed this time of this invention is an illustration and restrictive at no points. The scope of the present invention is not limited to the above detailed description, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. .

For example, in the nozzle plate manufacturing method of the present invention, a method using an SOI wafer has been shown, but the present invention is not limited to this, and the nozzle plate 21 may be manufactured using a Si substrate that does not use an SOI wafer.

In the formation of the large-diameter portion 213, the manufacturing method in which the average etching rate is changed in each of the top layer 213t, the middle layer 213m, and the bottom layer 213b has been described. It is not necessary to have a layer structure. For example, a two-layer configuration of a top layer 213t and a bottom layer 213b in which the average etching rate is changed only once may be used, or a configuration of four layers or more in which the average etching rate is changed three or more times may be used.

The shape of the large diameter portion 213 is not limited to the large diameter portion 213 formed in the direction perpendicular to the nozzle plate 21 as shown in FIG. 3, and can be selected as appropriate. For example, a tapered shape may be used so that the diameter of the large diameter portion 213 on the top layer 213t side is increased. Further, the large-diameter portion 213 is formed to have two or more steps so that the diameter decreases from the upper side to the lower side in FIG. 3, and the top layer 213t, the middle layer 213m, and the bottom layer are formed on each step. 213b may be provided so that each scallop width Wt, Wm, and Wb satisfies the above formula (1) or the above formula (2).

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Manufacturing method of nozzle plates 1 to 4>
Nozzle plates 1 to 4 having nozzle holes 211 composed of a small diameter portion 212 and a large diameter portion 213 were manufactured by an anisotropic etching method using a Bosch process.

(Formation of large diameter part)
As a Si substrate for manufacturing the nozzle plates 1 to 4, a

thermal oxide film

216, 217 made of SiO _{2 serving} as an etching mask and having a thickness of 1 μm is provided on both surfaces, and a thickness of 200 μm.
An SOI wafer was prepared (FIG. 4A). The thickness of the bonding layer 21b of the SOI wafer was 0.5 μm.

Next, after applying a photoresist 218 to the surface of the thermal oxide film 217 on the side where the large-diameter portion 213 is to be formed (FIG. 4B), the photoresist 218 is applied to the surface other than the upper surface where the large-diameter portion 213 is to be formed. A photoresist pattern 218a having a diameter of 100 μm was formed so as to be in a dry state (FIG. 4C). Next, a thermal oxide film pattern having a diameter of 100 μm was formed by dry etching using CHF ₃ using the photoresist pattern 218a as an etching mask, and this was used as an etching mask pattern 217a in the anisotropic etching method (FIG. 4D). Next, the photoresist pattern 218a was removed (FIG. 4E).

Next, using a Multiplex-ICP manufactured by Surface Technology Systems Limited, a large-diameter portion 213 having a diameter of 100 μm was formed by an anisotropic etching method in which etching and deposition were alternately repeated (FIGS. 4F, 4G, and FIG. 4). 4H). Thereafter, the etching mask pattern 217a was removed by dry etching using CHF ₃ (FIG. 4I).
Here, as shown in Table 1, the large diameter portion 213 is formed so as to have an average scallop width Wt of the top layer 213t, an average scallop width Wm of the middle layer 213m, and an average scallop width Wt of the top layer 213t. The large diameter portion 213 of the nozzle plates 1 to 4 was formed by adjusting the anisotropic etching conditions.
In this embodiment, the top layer 213t is formed to be 36 μm, the middle layer 213m is formed to be 108 μm, and the bottom layer 213b is formed to be 36 μm. Here, since the Si substrate having a thickness of 200 μm is used, the thickness of the remaining Si substrate was 20 μm.

(Formation of small diameter part)
Photoresist 219 was applied to the surface of the thermal oxide film 216 on the side where the small diameter portion 212 is to be formed (FIG. 5B) on the Si substrate on which the large diameter portion 213 was formed (FIG. 5A). Next, a photoresist pattern 219a having a diameter of 20 μm and concentric with the hole of the large-diameter portion 213 was formed so that the photoresist 219 was applied on the surface other than the upper surface of the position where the small-diameter portion 212 was formed (FIG. 5C). .
Next, a thermal oxide film pattern having a diameter of 20 μm was formed using the photoresist pattern 219a as an etching mask, and this was used as an etching mask pattern 216a in the anisotropic etching method (FIG. 5D). Next, the photoresist pattern 219a was removed (FIG. 5E).

Next, using a Multiplex-ICP manufactured by Surface Technology Systems Limited, etching is performed until the bonding layer 21b is exposed by an anisotropic etching method in which etching and deposition are alternately repeated, and the small-diameter portion 212 having a diameter of 20 μm is formed. Formed (FIG. 5F). Then, it was immersed in a diluted hydrofluoric acid solution to remove the etching mask pattern 216a and the bonding layer 21b exposed on the surface (FIG. 5G).
Here, in the formation of the small-diameter portion 212 in the nozzle plates 1 to 4, it is formed by adjusting the anisotropic etching conditions so that the average scallop width is 0.2 μm, and the nozzle plates 1 to 4 have the same small diameter. Part 212 was formed.
Moreover, the thickness of the formed small diameter part 212 was 20 micrometers.

Further, 1024 nozzle holes 211 constituted by the large diameter portion 213 and the small diameter portion 212 as described above were formed in the nozzle plates 1 to 4. Further, in the nozzle plates 1 to 4 manufactured by the above method, the liquid repellent layer 215 as shown in FIG. 3 was not provided.

<< Method for manufacturing inkjet heads 1 to 4 >>
The intermediate plate 22 and the body plate 23 as shown in FIGS. 1 and 2 were manufactured by a known method. Then, the head plate 2 is manufactured by bonding the intermediate plate 22 and the body plate 23 to each of the nozzle plates 1 to 4 manufactured as described above with an adhesive, and further, a holding plate is provided on the upper surface of the head chip 2. 3, the connecting member 4 and the ink flow path member 5 were formed to manufacture the ink jet heads 1 to 4.

≪Evaluation method≫
Using the inkjet heads 1 to 4 manufactured as described above, the following droplet ejection experiment was performed to evaluate the droplet ejection performance.
Each of the ink jet heads 1 to 4 is mounted on an ink jet recording apparatus, and ink is discharged from each of the 1024 nozzle holes 211 through the ink flow path member 5 through the inside of the head chip 2 for 10 seconds at 70 kPa. The ink was initially filled. Next, the ink was additionally charged by passing the ink from the ink flow path member 5 through the inside of the head chip 2 and discharging the ink from each of the 1024 nozzle holes 211 at 100 kPa for 10 seconds. After that, 3.5 pL droplets were ejected from 1024 nozzle holes 211 under the condition of 50 kHz, and the flight trajectory of the ejected ink droplets was photographed with a strobe camera. Then, it was observed whether ejection blur occurred in the ejected ink droplets.
The evaluation of ejection blur is based on the arrival position at which the ejected ink droplet is 1 mm away from the bottom surface of the nozzle plate 21 when the flying trajectory of 20 ink droplets ejected from each nozzle hole 211 is photographed with a strobe camera. In FIG. 1, it was evaluated that no ejection blur occurred when all 20 ink droplets were within 20 μm in diameter centered on a point perpendicular to the ink ejection direction. On the other hand, when there was an ink droplet that did not fit within a diameter of 20 μm, it was evaluated that ejection blur occurred.

Specifically, the ejection performance of the inkjet heads 1 to 4 was evaluated according to the following criteria, and ◎ and ○ were accepted.
(Double-circle): The injection blurring did not occur in all 1024 nozzle holes.
○: Injection blur occurred in 1 to 4 of 1024 nozzle holes.
Δ: Injection blur occurred in 5 to 9 of 1024 nozzle holes.
X: Injection blur occurred in 10 or more of 1024 nozzle holes.

≪Evaluation results≫
In the inkjet heads 1 to 3 using the nozzle plates 1 to 3 of the present invention, it was found that the occurrence of ejection blur was suppressed and the ejection performance was high. This is considered to be because the bubble-removing property of the nozzle was high and bubbles were not easily accumulated in the nozzle hole 211.
In addition, it was found that in the inkjet head 1 using the nozzle plate 1 of the present invention, no injection blur occurred in all the nozzle holes, and particularly good injection performance was obtained. This is because, by forming the middle layer more precisely, it was possible to minimize the influence of processing errors of each nozzle hole provided in the nozzle plate, and to obtain high injection performance in all nozzle holes. It is thought that.

The present invention can be used for a method for manufacturing a nozzle plate for a liquid discharge head, a nozzle plate for a liquid discharge head, and a liquid discharge head.

1 Liquid ejection head (inkjet head)
2 Head chip 21 Nozzle plate 211 Nozzle hole 212 Small diameter part 213 Large diameter part

213t Top layer

213m Middle layer

213b Bottom layer 215 Liquid repellent layer Wt Average scallop width Wm of top layer Average scallop width Wb of middle layer Average scallop width of bottom layer

Claims

An anisotropic etching method that alternately repeats etching and formation of the sidewall protective film on the Si substrate, and opens from the communication port communicating with the small-diameter portion to the other surface through the small-diameter portion that opens to one surface, A method for producing a nozzle plate for a liquid discharge head, which is provided with a nozzle hole having a larger diameter portion than a smaller diameter portion,
When the large-diameter portion is a top layer in contact with the other surface, from the other surface to the communication port, a bottom layer in contact with the communication port,
Forming the top layer with an average scallop width Wt;
Forming the bottom layer with an average scallop width Wb;
And satisfying the following formula (1), a method for manufacturing a nozzle plate for a liquid discharge head.
Formula (1): Wt> Wb
When the middle layer between the top layer and the bottom layer,
Forming the middle layer with an average scallop width Wm;
The method for manufacturing a nozzle plate for a liquid discharge head according to claim 1, wherein the following formula (2) is satisfied.
Formula (2): Wt>Wb> Wm
3. The method for manufacturing a nozzle plate for a liquid discharge head according to claim 1, wherein the anisotropic etching method is performed using a Bosch process.
4. The liquid ejection head according to claim 1, wherein the Si substrate includes a bonding layer made of a SiO 2 layer having a low etching rate between two Si layers. 5. Manufacturing method of nozzle plate.
The method for producing a nozzle plate for a liquid discharge head according to any one of claims 1 to 4, wherein a liquid repellent layer is formed on a surface where the small diameter portion opens.
6. The method for producing a nozzle plate for a liquid discharge head according to claim 5, wherein the thickness of the liquid repellent layer is in the range of 0.1 to 3.0 μm.
An anisotropic etching method that alternately repeats etching and formation of the sidewall protective film on the Si substrate, and opens from the communication port communicating with the small-diameter portion to the other surface through the small-diameter portion that opens to one surface, A nozzle plate for a liquid ejection head that has a nozzle hole having a larger diameter part than a smaller diameter part,
When the large-diameter portion is a top layer in contact with the other surface, from the other surface to the communication port, a bottom layer in contact with the communication port,
An average scallop width Wt of the top layer and an average scallop width Wb of the bottom layer satisfy the following formula (1).
Formula (1): Wt> Wb
8. The nozzle plate for a liquid discharge head according to claim 7, wherein an average scallop width Wm of the middle layer satisfies the following formula (2) when a middle layer is formed between the top layer and the bottom layer.
Formula (2): Wt>Wb> Wm
9. The nozzle plate for a liquid discharge head according to claim 7, further comprising a liquid repellent layer on a surface where the small diameter portion opens.
10. The nozzle plate for a liquid discharge head according to claim 9, wherein the thickness of the liquid repellent layer is in the range of 0.1 to 3.0 μm.
A liquid discharge head comprising a head chip having the nozzle plate for a liquid discharge head according to any one of claims 7 to 10.