JP2008110560A - Nozzle plate for liquid delivery head, and method for manufacturing nozzle plate for liquid delivering head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nozzle plate for a liquid delivering head having a nozzle capable of delivering stably ink and a method for manufacturing the nozzle plate for the liquid delivering head. <P>SOLUTION: The nozzle plate for the liquid delivering head which comprises a substrate with a through-hole, and in which the through-hole has a large-diameter part opening on one face side of the substrate and having a definite sectional shape, and a small-diameter part opening on the other face of the substrate and having a definite sectional shape having a smaller section than the section of the large-diameter part, and the opening of the small-diameter part of the through-hole is a delivering hole for delivering a liquid as liquid droplets, wherein the through-hole has a tapered part connected to the large-diameter part, gradually decreasing its diameter, and connected to the small-diameter part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In recent years, inkjet printers are required to print at high speed and high resolution. A semiconductor process for a silicon substrate or the like, which is a fine processing technique in the micromachine field, is used as a method for forming the components of the ink jet recording head used in this printer. For this reason, many methods for forming a fine structure by etching a silicon substrate have been proposed.

  When a nozzle plate having nozzles used in an ink jet recording head is made of metal or resin, the thickness is set to about 50 μm to 100 μm. In order to replace such a nozzle plate with a silicon substrate, it is necessary to make it thicker in handling because of the fragility of the silicon substrate. On the other hand, the diameter of the hole for ejecting ink droplets is expected to be smaller, for example, about 5 μm to 10 μm under a situation where a high-resolution recording head is strongly desired. In order to eject ink droplets from such minute ejection holes, the length of the ejection holes needs to be approximately the same as the diameter of the holes. In order to meet such requirements, there are the following methods for forming a minute nozzle diameter while ensuring the thickness of the silicon substrate.

An ink chamber cross section of a chamber plate having a small cross section nozzle formed by dry etching from one surface of a silicon substrate, and having a large cross section nozzle and an ink chamber, a pressure chamber, an ink supply path, etc. communicating with the large cross section nozzle A part of the substrate is dry-etched from the other surface of the silicon substrate to communicate with a nozzle having a small cross section to form a nozzle (see Patent Document 1).
JP 2004-106199 A

  However, according to the nozzle plate described in Patent Document 1, a small-diameter nozzle diameter is formed from one surface of the silicon substrate, and the large-section nozzle is dry-etched from the other surface to communicate with the small-section nozzle. The nozzle is formed, but a step is formed between the small diameter portion and the large diameter portion. When the ink flows, bubbles in the ink stay at a step portion where the ink flow is difficult to smooth, particularly at the end portion of the large diameter portion where the small diameter portion is open. When the bubbles that stay are gathered and become larger, variations in ink ejection characteristics such as that it becomes difficult to transmit a sufficient ejection force to the ejected ink or that only the bubbles exit from the nozzle holes instead of the ink are generated. In particular, in a multi-nozzle ink jet recording head having a plurality of nozzles, there is a problem that ink discharge characteristics vary among the nozzles and image quality is degraded.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a nozzle plate for a liquid discharge head and a nozzle plate for a liquid discharge head having nozzles that enable stable ink discharge. It is to provide a manufacturing method.

  Said subject is solved by the following structures.

1. Consisting of a substrate with through holes,
The through hole has a large-diameter portion having a constant cross-sectional shape opened to one surface side of the substrate;
A small-diameter portion having a constant cross-sectional shape that is open on the other surface of the substrate and has a cross-section smaller than that of the large-diameter portion,
In a nozzle plate for a liquid discharge head, wherein the opening of the small diameter portion of the through hole is a discharge hole for discharging liquid as droplets,
The through-hole has a taper portion in which a diameter gradually decreases continuously from the large diameter portion, and a diameter (Df) of a surface connected to the small diameter portion satisfies the following conditional expression: Nozzle plate.
d <Df ≦ 0.9D
However,
d: Diameter of the small diameter portion D: Diameter of the large diameter portion The base material of the substrate constituting the large diameter portion and the taper portion is Si, and the base material of the substrate constituting the small diameter portion is an Si anisotropic dry contact with the substrate constituting the large diameter portion and the taper portion. 2. The nozzle plate for a liquid discharge head according to 1, comprising a base material having an etching rate slower than that of Si.

3. 3. The nozzle plate for a liquid discharge head according to 2, wherein the base material whose etching rate in the Si anisotropic dry etching is slower than Si is SiO ₂ .

  4). 4. The nozzle plate for a liquid discharge head according to claim 1, wherein a liquid repellent layer is provided on a surface of the substrate on which the discharge hole is formed. 5.

5. A first base material made of Si, and a second base material including a base material whose etching rate in Si anisotropic dry etching provided in contact with one side of the first base material is lower than that of Si. Preparing a prepared substrate;
Performing a photolithography process and etching on the second base material to form a small diameter portion by perforating until the second base material is penetrated with an opening shape of the small diameter portion;
Forming a film serving as a first etching mask on the surface of the first base material; and performing a photolithography process and etching on the film serving as the first etching mask so as to have an opening shape of the large-diameter portion. Forming the etching mask pattern of 1 and the step of performing Si anisotropic dry etching until the following conditional expression is satisfied in the first base material and penetrated: The method for producing a nozzle plate for a liquid discharge head according to 1, wherein the step of forming the large diameter portion is performed in this order.
d <Df ≦ 0.9D
However,
d: Diameter of the small diameter portion Df: Diameter of the shape formed by the base material having a slower etching rate than Si and the tip portion of the large diameter portion formed D: Diameter of the large diameter portion A first base material made of Si, and a second base material including a base material whose etching rate in Si anisotropic dry etching provided in contact with one side of the first base material is lower than that of Si. Preparing a prepared substrate;
Forming a film serving as a first etching mask on the surface of the first base material; and performing a photolithography process and etching on the film serving as the first etching mask so as to have an opening shape of the large-diameter portion. Forming the etching mask pattern of 1 and the step of performing Si anisotropic dry etching until the following conditional expression is satisfied in the first base material and penetrated: Including the step of forming said large diameter portion;
Performing a photolithography process and etching on the second base material to form the small diameter portion in this order by drilling until the second base material is penetrated with the opening shape of the small diameter portion. 2. A method for producing a nozzle plate for a liquid ejection head as described in 1 above.
d <Df ≦ 0.9D
However,
d: Diameter of the small diameter portion Df: Diameter of the shape formed by the base material having a slower etching rate than Si and the tip portion of the large diameter portion formed D: Diameter of the large diameter portion Method of manufacturing a nozzle plate for a liquid discharge head according to 5 or 6, wherein the slow substrate etching rate than Si in the Si anisotropic dry etching is SiO _2.

  8). 8. The method for manufacturing a nozzle plate for a liquid discharge head according to claim 5, further comprising a step of providing a liquid repellent layer on a surface of the substrate on which the discharge holes are formed.

In the nozzle plate for a liquid discharge head according to the present invention, the through hole has a tapered portion in which the diameter gradually decreases continuously from the large diameter portion, and the diameter (Df) of the surface connected to the small diameter portion satisfies the following conditional expression. is doing.
d <Df ≦ 0.9D
However,
d: Diameter of the small-diameter portion D: Diameter of the large-diameter portion Therefore, there is a taper portion where the diameter of the large-diameter portion gradually decreases between the large-diameter portion and the small-diameter portion. The flow of the liquid becomes smooth, and bubbles contained in the liquid do not stay between the large diameter portion and the small diameter portion. For this reason, the pressure at the time of discharging the liquid as a droplet is not weakened by the staying bubbles, and the bubble that stays and gathers small bubbles and grows large is not discharged instead of the droplets.

  Therefore, it is possible to provide a nozzle plate for a liquid discharge head having nozzles that enable stable ink discharge.

Further, according to the method for manufacturing a nozzle plate for a liquid discharge head of the present invention, the etching rate in the first base material made of Si and the Si anisotropic dry etching provided in contact with one side of the first base material Using a substrate provided with a second base material including a base material that is slower than Si, performing the anisotropic dry etching until the first base material satisfies the following conditional expression and penetrates: A large diameter portion including a tapered portion is formed. Further, the second base material is perforated until it penetrates the second base material with an opening shape of a small diameter part to form a small diameter part.
d <Df ≦ 0.9D
However,
d: Diameter of the small diameter portion Df: Diameter of the shape formed by the base material having a slower etching rate than Si and the tip of the large diameter portion formed D: Diameter of the large diameter portion Therefore, the large diameter portion and the small diameter portion A taper portion in which the diameter of the large diameter portion gradually decreases is formed between them, and the flow of the liquid discharged as droplets becomes smooth by this taper portion, and bubbles contained in the liquid are between the large diameter portion and the small diameter portion. No longer stay in the water. For this reason, the pressure at the time of discharging the liquid as a droplet is not weakened by the staying bubbles, and the bubble that stays and gathers small bubbles and grows large is not discharged instead of the droplets.

  Therefore, it is possible to provide a method for manufacturing a nozzle plate for a liquid discharge head having nozzles that enable stable ink discharge.

  Although the present invention will be described based on the illustrated embodiment, the present invention is not limited to the embodiment.

  FIG. 1 schematically shows a nozzle plate 1, a body plate 2, and a piezoelectric element 3 constituting an ink jet recording head (hereinafter referred to as a recording head) A which is an example of a liquid discharge head.

  A plurality of nozzles 11 for discharging ink are arranged on the nozzle plate 1. Further, the nozzle plate 1 is bonded to the body plate 2 so that the pressure chamber groove 24 serving as a pressure chamber, the ink supply path groove 23 serving as an ink supply path, the common ink chamber groove 22 serving as a common ink chamber, and the ink. A supply port 21 is formed.

  And the flow path unit M is formed by bonding the nozzle plate 1 and the body plate 2 so that the nozzle 11 of the nozzle plate 1 and the pressure chamber groove 24 of the body plate 2 correspond one-to-one. Hereafter, the reference numerals of the pressure chamber groove, the supply path groove, and the common ink chamber groove used in the above description are also used for the pressure chamber, the supply path, and the common ink chamber, respectively.

  Here, FIG. 2 schematically shows a cross section of the recording head A at the positions of YY of the nozzle plate 1 and XX of the body plate 2. As shown in FIG. 2, the piezoelectric element 3 is bonded to the flow path unit M to the surface of the bottom 25 of each pressure chamber 24 opposite to the surface to which the nozzle plate 1 of the body plate 2 is bonded. Thus, the recording head A is completed. A drive pulse voltage is applied to each piezoelectric element 3 of the recording head A, and vibration generated from the piezoelectric element 3 is transmitted to the bottom 25 of the pressure chamber 24, and the pressure in the pressure chamber 24 is changed by the vibration of the bottom 25. Thus, ink droplets are ejected from the nozzle 11.

  FIG. 3 shows a peripheral portion of the nozzle 11 as an example of the nozzle plate 1. The nozzle plate 1 shown in FIG. 3 has a three-layer structure of a Si substrate 30, an etching stop layer 31, and a Si layer 32, and a liquid repellent layer 45 is provided thereon. The nozzle 11 includes a large diameter portion 15, a small diameter portion 14, and a portion 18 (hereinafter referred to as a taper portion 18) connected to the small diameter portion, the diameter of which gradually decreases continuously.

In the configuration of the large diameter portion 15, the small diameter portion 14, and the taper portion 18 shown in FIG. 3, d is the diameter of the small diameter portion 14, D is the diameter of the large diameter portion, and Df is the diameter of the small diameter portion 14 on the large diameter portion 15 side. The following conditional expression (1) is satisfied as the diameter of the tapered portion 18 intersecting with the plane having the opening end face in the plane.
d <Df ≦ 0.9D (1)
When the diameter Df of the taper portion 18 is less than the diameter d of the small diameter portion 14, the large diameter portion 15 and the small diameter portion 14 penetrate, but the large diameter portion 15 does not reach the etching stop layer 31. The small-diameter portion 14 is not opened with a constant cross-sectional shape, and the length of the small-diameter portion 14 is longer than a predetermined length. In this case, since the opening is not sufficient and the small-diameter portion 14 is longer than a predetermined length, the flow resistance of the small-diameter portion 14 is increased, and the droplet discharge performance is deteriorated.

  When the diameter Df of the tapered portion 18 exceeds 0.9 times the diameter D of the large-diameter portion, the bubbles contained in the discharge liquid are retained in the corner portion where the tapered portion 18 intersects the etching stop layer 31. . When the bubbles stay, the bubbles are accumulated and gradually grow, and finally the pressure for discharging the droplets is absorbed. As a result, the pressure cannot be sufficiently transmitted to the discharge liquid, or the grown bubbles come out of the discharge holes, so that the formed image quality is deteriorated.

  Here, the manufacture of the nozzle plate 1 will be described. 4 and 5 are diagrams schematically showing a process of manufacturing the nozzle plate 1 of FIG. 1 with a cross-sectional view, and the completed nozzle plate 1 is shown in FIG. FIG. 5 (h) shows a more preferable nozzle plate including the liquid repellent layer 45.

  A substrate C (FIG. 4A) for manufacturing the nozzle plate 1 is provided with a so-called etching stop layer 31 made of a material having an etching rate slower than Si on a Si substrate 30 as a first base material, and further includes a Si layer 32. ing. The etching stopper layer 31 and the Si layer 32 serve as the second base material. The Si substrate 30 is provided with a large-diameter portion described later, and the etching stop layer 31 and the Si layer 32 are provided with a small-diameter portion. The thickness of the Si substrate 30 is appropriately determined depending on the length of the large diameter portion, and the thicknesses of the etching stop layer 31 and the Si layer 32 are appropriately determined depending on the length of the small diameter portion serving as the nozzle length. At this time, the thickness of the etching stopper layer 31 may be determined as appropriate in relation to the etching rate with Si depending on the material used.

  The three-layered substrate C is commercially available as SOI (Silicon On Insulator) and can be obtained by specifying the material and thickness. For example, the substrate C can be manufactured as follows.

First, the etching stop layer 31 is provided on the Si substrate 30. The material of the etching stop layer 31 needs to have an etching rate in Si anisotropic dry etching smaller than the etching rate of Si. In addition, a material capable of forming a small-diameter portion by etching, for example, a hole capable of forming a hole of about 1 μm to 10 μm is used. Examples of such materials include insulating materials such as SiO ₂ and Al ₂ O ₃ , metals such as Ni and Cr, and resins such as photoresist.

The etching rate compared to Si is about 1/300 to 1/200 for SiO ₂ and Al ₂ O _3, about 1/500 for Ni and Cr, and about 1/50 for resins such as photoresist when Si is 1. It is. Here, the etching rate ratio in which Si is 1 is defined as an etching selection ratio. These etching selection ratios are approximate values because they vary depending on etching conditions such as an etching apparatus and an etching rate.

  Since the thickness of the etching stop layer 31 is a part of the nozzle length, the thickness may be determined together with the Si layer 32 provided on the etching stop layer 31 thereafter. The formation method of the etching stop layer 31 is not particularly limited, and may be a known method. Examples thereof include a vacuum deposition method, a sputtering method, a CVD method, and the like, and may be appropriately selected according to the material to be used.

Thereafter, the Si layer 32 is provided. The formation method is not particularly limited, and a known method may be used. For example, a CVD (Chemical Vapor Deposition) method may be used with a reactive gas as a silane (SiH ₄ ) gas.

  Next, the formation of the large diameter portion 15 will be described with reference to FIG. The large diameter portion 15 is formed using the substrate C. When arranging a plurality of large-diameter portions 15, the strength of the partition walls is secured so that the interference of the pressurizing force on the liquid in the nozzle of the adjacent large-diameter portions 15 does not become a problem. It is good to set it as the diameter which can have thickness. Further, it is preferable to appropriately determine the pitch of the interval between the small diameter portions 14 in consideration.

First, a film 40 serving as an etching mask for providing the large diameter portion 15 is provided on the Si substrate 30 of the substrate C by a known photolithography process. The film 40 is not particularly limited as long as it serves as an etching mask for performing Si anisotropic dry etching on the Si substrate 30. For example, there is a SiO ₂ film. In order to form a mask pattern on the film 40, a photoresist pattern 42a is formed (FIG. 4B). Next, an SiO ₂ etching mask 40a is formed by using a known reactive dry etching method using CF ₄ gas with the photoresist pattern 42a as a mask (FIG. 4C). The photoresist pattern 42a is removed by ashing using oxygen plasma or the like.

  Next, the large diameter portion 15 is formed so as to penetrate the small diameter portion 14 using the Si anisotropic dry etching method and satisfy the conditional expression (1). At this time, the material of the etching stop layer 31 has a small etching selectivity. For this reason, when the large diameter portion 15 is processed, the etching rate in the depth direction in the portion where the etching stop layer 31 is exposed decreases.

As an example, if the etching selectivity of SiO ₂ that is the etching stop layer 31 is 1/200, the etching amount of the etching stop layer 31 is 0.05 μm when the Si substrate 30 is etched by 10 μm. Therefore, the etching in the depth (length) direction of the portion where the etching process reaches the etching stop layer 31 and the etching stop layer 31 is exposed hardly progresses.

In addition, the shape of the large-diameter portion formed by the etching process is not the same as the circular shape that is the shape of the etching mask up to the tip, and the diameter of the circle with a cross-sectional shape is closer to the tip than the diameter of the large-diameter portion It is getting smaller. The connection state of the distal end portion of the large diameter portion 15 that has reached the etching stop layer 31 with the small diameter portion 14 changes in the following order as the etching process proceeds.
(1) The small diameter portion 14 is penetrated by a hole smaller than the diameter d of the small diameter portion 14.
(2) The opening diameter of the small diameter portion 14 gradually increases until the entire area of the small diameter portion 14 opens.
(3) Further, when the etching proceeds, the exposed surface of the etching stopper layer 31 spreads outward from the opening of the small diameter portion 14.
(4) Finally, it reaches the same diameter as the large diameter portion 15.
Here, the states shown in (2) and (3) are provided with a tapered portion that makes the large diameter portion and the small diameter portion smaller than the diameter of the large diameter portion and leads to the small diameter portion. In the state shown in (2) and (3), the diameter of the tapered portion that intersects the plane having the opening end face of the small diameter portion on the large diameter portion side in the plane, or an etching stop layer that is a base material whose etching rate is slower than Si Conditional expression (1) and more preferably conditional expression (2) described later are applied, where Df is the diameter of the shape formed by the intersection of 31 and the tip of the large-diameter part formed. Therefore, the amount of etching for forming the large diameter portion 15 is determined in advance through experiments or the like, so that the shape of the large diameter portion 15 satisfies the conditional expression (1), more preferably the conditional expression (2) described later. be able to.

  As the Si anisotropic dry etching, for example, an ICP (Inductive Coupling Plasma) type RIE (Reactive Ion Etching) apparatus corresponding to the Bosch process is preferable.

  Next, the formation of the small diameter portion 14 will be described with reference to FIG. 5 using the substrate C (FIG. 5A) on which the large diameter portion 15 is formed as described above.

First, a film 34 serving as an etching mask for providing the small diameter portion 14 is provided on the Si layer 32 by a known photolithography process (FIG. 5B). The film 34 is not particularly limited as long as it serves as an etching mask when the Si layer 32 is subjected to Si anisotropic dry etching. For example, there is a SiO ₂ film. In order to form a mask pattern on the film 34, a photoresist pattern 36a is formed (FIG. 5C). Next, an SiO ₂ etching mask 34a is formed by using a known reactive dry etching method using CF ₄ gas with the photoresist pattern 36a as a mask (FIG. 5D). Thereafter, the photoresist pattern 36a is removed by ashing using oxygen plasma or the like (FIG. 5E).

  Next, etching is performed using the Si anisotropic dry etching method until the etching stop layer 31 is exposed (FIG. 5F). At this time, it is preferable that the etching stop layer 31 is exposed in the entire cross-section forming the small diameter portion 14. By doing so, no protrusions or the like that obstruct the flow of ink are formed on the small diameter portion. Further, the etching stop layer 31 has a small etching selectivity. For this reason, after the etching process reaches the etching stop layer 31, the speed of processing the small diameter portion 14 in the length direction decreases. As a result, the etching amount can be easily controlled, and the etching stop layer 31 can be easily exposed in the entire cross-section of the small-diameter portion 14 by overetching.

Next, the etching stop layer 31 is removed (FIG. 5G). The removal method may be appropriately selected depending on the material of the etching stop layer 31. For example, a known reactive dry etching method using wet etching is used for metals such as Ni and Cr, and CF ₄ gas is used for SiO _2. is there. By removing the etching stop layer 31, the small diameter portion 14 penetrates the large diameter portion 15 and the nozzle is completed.

  As described above, for example, if a plurality of nozzle plates are formed on a single Si substrate, the nozzle plates may be separated into individual nozzle plates by a dicing saw or the like.

  In the above example, the large-diameter portion 15 is first formed on the substrate C, and then the small-diameter portion 14 is formed. However, in this order, the small-diameter portion 14 is first formed and then the large-diameter portion 15 is formed. You can also.

Also, the base material of the substrate which constitutes the small diameter portion 14, for example, and constitute the material, for example, a small-diameter portion 14 only of SiO ₂ constituting the etch stop layer 31 as shown in FIG. The method for forming the small-diameter portion 14 in FIG. 6 can be the same as the etching mask 34a described above, for example. That is, a photoresist pattern for forming the small diameter portion 14 is provided, and then the small diameter portion 14 penetrating the large diameter portion 15 is formed by, for example, a known reactive dry etching method using CF ₄ gas.

When the large-diameter portion 15 and the small-diameter portion 14 are actually formed on the substrate C, it is necessary to perform etching by performing photolithography from both sides of the substrate C. In this case, it is necessary to position a photomask for forming an etching mask pattern on both surfaces of the substrate C using a mask aligner. Therefore, when the patterns on both sides are positioned, a positional shift that depends on the accuracy of the mask aligner used occurs. This misalignment may cause the center of the large diameter portion 15 and the small diameter portion 14 to deviate. When this deviation occurs, when the diameter Df of the tapered portion 18 in the conditional expression (1) is close to the diameter d of the small diameter portion 14, the length of the small diameter portion 14 is not constant. If the length of the small diameter portion 14 is not constant, the flow path resistance of the small diameter portion 14 is not uniform. As a result, the discharged droplets are inclined and discharged, and the image quality that can be formed deteriorates. For these reasons, it is more preferable that the following conditional expression (2) is satisfied.
2d ≦ Df ≦ 0.9D (2)
In the examples so far, the nozzle has a two-stage configuration of the small-diameter portion 14 and the large-diameter portion 15. However, the nozzle may have a three-stage configuration and three or more stages as shown in FIG. In the case of three stages, conditional expression (1) can be applied to each diameter with 71 shown in FIG. 7 as a small diameter part, 73 as a large diameter part, and 75 as a tapered part. In addition, the diameter of the largest largest diameter part 77 should just be a diameter larger than the diameter D of the large diameter part 73, and does not affect conditional expression (1).

  The liquid repellent layer 47 will be described. It is preferable to provide a liquid repellent layer 45 on the surface of the nozzle plate 11 shown in FIG. By providing the liquid repellent layer 45, it is possible to suppress the seepage and spread when the liquid is adapted to the discharge surface 12 from the discharge hole 13. Specifically, for example, a material having water repellency is used if the liquid is aqueous, and a material having oil repellency is used if the liquid is oily. Generally, FEP (ethylene tetrafluoride, propylene hexafluoride) is used. ), PTFE (polytetrafluoroethylene), fluorosiloxane such as fluorosiloxane, fluoroalkylsilane, amorphous perfluororesin, and the like are often used, and the film is formed on the discharge surface 12 by a method such as coating or vapor deposition. The thickness of the film is not particularly limited, but is preferably about 0.1 μm to 3 μm.

  The liquid repellent layer 45 may be formed directly on the ejection surface 12 of the nozzle plate 1 or may be formed via an intermediate layer in order to improve the adhesion of the liquid repellent layer 45. .

The Example which manufactures the nozzle plate 1 using FIG. 4, FIG. 5 is demonstrated. First, the formation of the large diameter portion 14 will be described with reference to FIG. A SiO ₂ film having a thickness of 0.5 μm was formed as an etching stop layer 31 on one surface of a Si substrate 30 having a thickness of 200 μm, and a Si layer 32 having a thickness of 4.5 μm was further formed thereon (FIG. 4A). The CVD method was used as the forming method. This was designated as substrate C.

  A nozzle having a diameter of the small diameter portion 14 of 5 μm and a diameter of the large diameter portion 15 of 60 μm was formed on the substrate C.

A SiO ₂ film having a thickness of 1.2 μm as a film 40 was formed on the other surface of the Si substrate 30 by a CVD method. A photoresist pattern 42a is formed on the SiO ₂ film (FIG. 4B). An etching process is performed using the photoresist pattern 42a to obtain an etching mask 40a made of SiO ₂ (FIG. 4C). The photoresist pattern 42a is removed by an ashing method using oxygen plasma.

  Using the etching mask 40a, the Si substrate 30 was etched by Si anisotropic dry etching to form the large diameter portion 15 (FIG. 4D). The etching amount for forming the large-diameter portion 15 was previously set by experiments and the like so that the diameter Df of the tapered portion 18 will be described later.

As a specific method of Si anisotropic dry etching, a Bosch process was used. Sulfur hexafluoride (SF ₆ ) was used as an etching gas, and fluorocarbon (C ₄ F ₈ ) was used alternately as a deposition gas. Table 1 below shows the settings of an ICP type RIE apparatus which is an etching apparatus.

  According to the etching conditions shown in Table 1, the etching rate is 1 μm / cycle. The etching amount was determined by adjusting the number of cycles. In addition, when it is necessary to adjust the etching amount more finely, it can be dealt with by adjusting the etching power and the platen power.

After forming the large-diameter portion 15, the SiO ₂ film used as the etching mask 40a was removed by reactive ion etching (RIE) (FIG. 4E).

Next, a SiO ₂ film having a thickness of 0.3 μm, which is a film 34 to be the etching mask 34a, was formed by sputtering (FIG. 5B). A photoresist pattern 36a was formed on the SiO ₂ film by photolithography (FIG. 5C). After that, an SiO ₂ film pattern, which is an etching mask 34a for forming the small diameter portion 14 having a diameter of 5 μm with the discharge hole as an opening on the Si film 32 of the substrate C, was formed by etching (FIG. 5D). Thereafter, the photoresist pattern 36a was removed.

Using the etching mask 34a, the Si layer 32 was etched by dry etching using CF ₄ as a reactive gas to form the small diameter portion 14 (FIG. 5F). Thereafter, the etching stop layer 31 was removed by a known reactive dry etching method using CHF ₃ gas, and the small diameter portion 14 and the large diameter portion 15 were penetrated.

  The nozzle plate 1 having nozzle holes was produced by separating the Si substrate 30 having nozzle holes formed by the above-described procedure with a dicing saw.

  Next, the body plate 2 shown in FIG. 1 was manufactured. Using a Si substrate, using a known photolithography process (resist application, exposure, development) and Si anisotropic dry etching technology, a pressure chamber groove serving as a plurality of pressure chambers respectively communicating with the nozzles, An ink supply groove serving as a plurality of ink supply paths communicating with each other, a common ink chamber groove serving as a common ink chamber communicating with the ink supply, and an ink supply port were formed.

  Next, as shown in FIG. 1, the nozzle plate 1 and the body plate 2 that have been prepared so far are bonded together using an adhesive, and the piezoelectric plate serving as a pressure generating means is attached to the back surface of each pressure chamber 24 of the body plate 2. The element 3 was attached to form a droplet discharge head A.

  The following is a result of a droplet discharge experiment in which a droplet discharge head A was prepared using a nozzle plate prepared by changing the etching amount so that the diameter Df of the tapered portion 18 was as follows.

The diameter Df of the tapered portion 18 was observed and measured with an optical microscope from the opening side of the large diameter portion 15. A glass scale was used for measuring the diameter. In the large-diameter portion 15 observed with an optical microscope, the exposed SiO ₂ film as the etching stop layer 31 is glossy, and the etched Si portion is rough, so that the boundary between the two is judged well. it can.

Each symbol shown in the discharge experiment results in Table 2 means the following.
○: Good Δ: Discharge unevenness sometimes occurred ×: Bad In Examples 2 to 5, droplets were discharged better than the droplet discharge head A. In the first embodiment, there is a case where a positional shift of about the radius of the small diameter portion occurs. In the droplet discharge head A using this, there was a phenomenon that the discharge amount of the droplet was uneven and the discharge direction was inclined. In the case where no displacement was observed, the droplets were ejected better than the droplet ejection head A.

  In Comparative Example 1, the small diameter portion is not penetrated with a constant opening shape. In the droplet ejection head A using this, ejection failure occurred. In Comparative Example 2, there was a case where droplets were not occasionally ejected from the droplet ejection head A, resulting in recording unevenness. In Comparative Example 3, there was a case where droplets were not frequently ejected from the droplet ejection head A, resulting in recording unevenness.

It is a figure which shows the example of an inkjet recording head. It is a figure which shows the cross section of an ink jet recording head. It is a figure which shows the example of the discharge hole periphery of a nozzle plate. It is a figure which shows the process of forming a large diameter part. It is a figure which shows the process of forming a small diameter part. It is a figure which shows the example of the discharge hole periphery of a nozzle plate. It is a figure which shows the example of the discharge hole periphery of a nozzle plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle plate 2 Body plate 3 Piezoelectric element 11 Nozzle 12 Ejection surface 13 Ejection hole 14 Small diameter part 15 Large diameter part 18 Taper part 21 Ink supply port 22 Common ink chamber (groove)
23 Ink supply path (groove)
24 Pressure chamber (groove)
30 Si substrate 32 Si layer 34, 40 Film 40a, 34a Etching mask 42a, 36a Photoresist pattern 45 Liquid repellent layer A Inkjet recording head C substrate

Claims (8)

Consisting of a substrate with through holes,
The through hole has a large-diameter portion having a constant cross-sectional shape opened to one surface side of the substrate;
A small-diameter portion having a constant cross-sectional shape that is open on the other surface of the substrate and has a smaller cross-section than the cross-section of the large-diameter portion,
In a nozzle plate for a liquid discharge head, wherein the opening of the small diameter portion of the through hole is a discharge hole for discharging liquid as droplets,
The through-hole has a taper portion in which a diameter gradually decreases continuously from the large diameter portion, and a diameter (Df) of a surface connected to the small diameter portion satisfies the following conditional expression: Nozzle plate.
d <Df ≦ 0.9D
However,
d: Diameter of the small diameter portion D: Diameter of the large diameter portion The base material of the substrate constituting the large diameter portion and the taper portion is Si, and the base material of the substrate constituting the small diameter portion is an Si anisotropic dry contact with the substrate constituting the large diameter portion and the taper portion. The nozzle plate for a liquid discharge head according to claim 1, comprising a base material whose etching rate in etching is slower than that of Si. 3. The nozzle plate for a liquid discharge head according to claim ₂ , wherein the base material whose etching rate in the Si anisotropic dry etching is slower than Si is SiO2. 4. The nozzle plate for a liquid discharge head according to claim 1, wherein a liquid repellent layer is provided on a surface of the substrate on which the discharge holes are formed. 5. A first base material made of Si, and a second base material including a base material whose etching rate in Si anisotropic dry etching provided in contact with one side of the first base material is lower than that of Si. Preparing a prepared substrate;
Performing a photolithography process and etching on the second base material to form a small diameter portion by perforating until the second base material is penetrated with an opening shape of the small diameter portion;
Forming a film serving as a first etching mask on the surface of the first base material; and performing a photolithography process and etching on the film serving as the first etching mask so as to have an opening shape of the large-diameter portion. Forming the etching mask pattern of 1 and the step of performing Si anisotropic dry etching until the following conditional expression is satisfied in the first base material and penetrated: The method of manufacturing a nozzle plate for a liquid discharge head according to claim 1, wherein the step of forming the large-diameter portion is performed in this order.
d <Df ≦ 0.9D
However,
d: Diameter of the small diameter portion Df: Diameter of the shape formed by the base material having a slower etching rate than Si and the tip portion of the large diameter portion formed D: Diameter of the large diameter portion A first base material made of Si, and a second base material including a base material whose etching rate in Si anisotropic dry etching provided in contact with one side of the first base material is lower than that of Si. Preparing a prepared substrate;
Forming a film serving as a first etching mask on the surface of the first base material; and performing a photolithography process and etching on the film serving as the first etching mask so as to have an opening shape of the large-diameter portion. Forming the etching mask pattern of 1 and the step of performing Si anisotropic dry etching until the following conditional expression is satisfied in the first base material and penetrated: Including the step of forming said large diameter portion;
Performing a photolithography process and etching on the second base material to form the small diameter portion in this order by drilling until the second base material is penetrated with the opening shape of the small diameter portion. The method for manufacturing a nozzle plate for a liquid discharge head according to claim 1.
d <Df ≦ 0.9D
However,
d: Diameter of the small diameter portion Df: Diameter of the shape formed by the base material having a slower etching rate than Si and the tip portion of the large diameter portion formed D: Diameter of the large diameter portion The method of manufacturing a nozzle plate for a liquid discharge head according to claim 5 or 6, wherein the base material whose etching rate in the Si anisotropic dry etching is slower than Si is SiO ₂ . 8. The method for manufacturing a nozzle plate for a liquid discharge head according to claim 5, further comprising a step of providing a liquid repellent layer on a surface of the substrate on which the discharge holes are formed. .

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