Method for manufacturing a nozzle plate

Abstract

The present invention produces, through steps 1-5 described below, a nozzle plate having a nozzle hole that has formed therein at least a tapered nozzle portion 12 and a straight communication channel 13. Step 1 (S-1): a step for preparing a mono-crystalline silicon substrate 1 in which the surface crystal orientation is a (100) plane. Step 2 (S-2): a step for uniformly forming a mask layer 2 on the surface of the mono-crystalline silicon substrate. Step (S-3): a step for forming an opening pattern 3 in the mask layer. Step 4 (S-4): a step for forming a through hole 4 by performing penetration machining on the mono-crystalline silicon substrate which is located under the opening pattern, through dry etching from the surface of the substrate. Step 5 (S-5): a step for forming a tapered nozzle portion and a straight communication channel which is contiguous to said tapered nozzle portion, by expanding the through hole through anisotropic wet etching on the mono-crystalline silicon substrate.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a nozzle plate. According to the method

Background Art

[0002] Conventionally, a method for manufacturing a nozzle plate having a nozzle taper portion and a straight communication passage in a nozzle hole has been proposed. Such a method for manufacturing a nozzle plate is disclosed in, for example, Patent Document 1 and Patent Document 2.

[0003] Patent Document 1 discloses a method for manufacturing a funnel-shaped nozzle plate in which a nozzle taper portion and a nozzle straight portion are formed on an SOI (Silicon On Insulator) substrate, which is a silicon wafer having a structure in which a silicon single crystal layer is formed on an oxide film. In Patent Document 1, for the hole formed by wet etching, a photoresist is patterned from the opposite side to etch the subsequent hole. That is, it is a method of making the hole dug from one surface of the substrate and the hole dug from the other surface meet and open inside the substrate. Also in Patent Document 2, since wet etching is performed from above and below without penetrating the hole from one side, it is the same method.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] ​In the above prior art, a nozzle hole is formed by causing a hole drilled from one surface of the substrate to meet and open with a hole drilled from the other surface within the substrate. However, misalignment between the hole drilled from one surface and the hole drilled from the other surface is inevitable. Therefore, according to the above conventional manufacturing method, due to misalignment between the nozzle taper portion and the straight communication passage, the flow of the fluid loses symmetry, and there is a risk that the injection angle deteriorates. Furthermore, due to this misalignment, stagnation may occur within the nozzle, bubbles may accumulate therein, and there is a risk that the degassing property also deteriorates.

[0006] The present invention has been made in view of the above problems, and the problem to be solved is to configure a nozzle plate in which the nozzle taper portion and the straight communication passage are continuous without misalignment, and a fluid discharge head including the same.

Means for Solving the Problems

[0007] One aspect of the present invention for solving the above problems is a method for manufacturing a nozzle plate of a fluid discharge head, and includes the following Step 1 , steps 2, 3, 6 Step 7 , and the steps are performed in the order of step 4 and step 5 Via by doing so This is a method for manufacturing a nozzle plate for manufacturing a nozzle plate having at least a nozzle taper portion and a straight communication passage in a nozzle hole. Step 1: A step of preparing a single crystal silicon substrate whose crystal orientation on the surface is the

[0100] plane, Step 2: A step of uniformly forming a mask layer on the surface of the single crystal silicon substrate, Step 3: A step of forming an opening pattern in the mask layer, Step 6: A step of forming a hole portion by deeply etching the single crystal silicon substrate under the opening pattern from the surface by dry etching, Step 7: A step of forming a mask layer on the side wall of the hole portion, Step 4: A step of forming a through hole by penetrating the single crystal silicon substrate under the opening pattern from the surface by dry etching, Step 5: Forming a nozzle taper portion and a straight communication passage continuous with the nozzle taper portion by expanding the through hole formed through one opening pattern for each nozzle by anisotropic wet etching of the single crystal silicon substrate.

Advantages of the Invention

[0009] According to the method for manufacturing a nozzle plate of a fluid ejection head according to one aspect of the present invention, for each nozzle, the through hole formed through one opening pattern is expanded to form a nozzle taper portion and a straight communication passage, so that a nozzle plate in which the nozzle taper portion and the straight communication passage are continuously formed without misalignment can be configured.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0012] 〔First Embodiment〕 First, the manufacturing method of the nozzle plate according to the first embodiment of the present invention and the nozzle plate manufactured thereby will be described. The manufacturing method of the nozzle plate of the present invention is a manufacturing method of the nozzle plate of a fluid ejection head. Through the following steps 1 to 5, a nozzle plate having at least a nozzle taper portion and a straight communication passage in the nozzle hole is manufactured. The reference diagrams of steps 1 (S-1) to 5 (S-5) are shown in FIG. 1.

[0013] First, as step 1 (FIG. 1 S-1), a single crystal silicon substrate 1 having a crystal orientation of the surface being the

[0100] plane is prepared. The single crystal silicon substrate 1 having a surface of the

[0100] plane is a plate-like member made of silicon having a thickness of about 100 to 725 μm. By using the single crystal silicon substrate 1 as the base material of the nozzle substrate, the nozzle plate can be processed with high precision, and a nozzle plate with less positional error and shape variation can be formed.

[0014] Next, as step 2 (FIG. 1 S-2), a mask layer 2 is uniformly formed on the surface of the single crystal silicon substrate 1. The material for forming the mask layer 2 is not particularly limited. For example, SiO 2 (silicon oxide), SiN (silicon nitride), Al (aluminum), Cr (chromium), etc. can be used.

[0015] As a method for forming the mask layer, for example, SiO 2Regarding the formation of the mask layer composed of, thermal oxidation method or CVD method (chemical vapor deposition, chemical vapor growth method) can be applied. Regarding the formation of the mask layer composed of SiN, CVD method or LPCVD method (low pressure CVD method, low pressure vapor growth method) can be applied. Preferably, SiO formed by thermal oxidation method 2 is used. SiO 2 has good adhesion to Si and has the effect of preventing side etching during anisotropic wet etching.

[0016] The mask layer 2 may be a single layer or a two-layer structure as shown in FIG. 1. Further, the mask layer 2 may also be formed on the back side of the silicon substrate 1 in this step.

[0017] Next, as step 3 (FIG. 1 S-3), a circular or polygonal opening pattern 3 is formed in the mask layer 2. Specifically, by a well-known photolithography technique, a resist pattern is formed on the mask layer 2, and the mask layer 2 is dry-etched (DE1) using the resist pattern as a mask to form the opening pattern 3.

[0018] For the formation of the resist layer, a positive photoresist or a negative photoresist can be used. As the positive photoresist and the negative photoresist, known materials can be used. For example, as the negative photoresist, ZPN-1150-90 manufactured by Nippon Zeon Co., Ltd. can be used. Also, as the positive photoresist, OFPR-800LB and OEBR-CAP112PM manufactured by Tokyo Ohka Kogyo Co., Ltd. can be used.

[0019] The resist layer is formed by coating it to a predetermined thickness using a spin coater or the like. Then, a pre-bake treatment is performed under conditions such as 110°C for 90 seconds.

[0020] For improving adhesion, HMDS (hexamethyldisilazane) treatment may be performed before resist coating. HMDS treatment is an organic material called hexamethyldisilazane. For example, OAP (hexamethyldisilazane) manufactured by Tokyo Ohka Kogyo Co., Ltd. can be used. Similar to resist coating, it can be applied with a spin coater, or exposure to hexamethyldisilazane vapor can also be expected to improve the adhesion effect.

[0021] Using a predetermined mask, expose the resist layer with an aligner or the like. For example, in the case of a contact aligner, it is performed with a light amount of about 50 mJ / cm 2 . Then, immerse it in a developer (for example, NMD-3 manufactured by Tokyo Ohka Kogyo Co., Ltd. for 60 to 90 seconds), and by removing the photosensitive part of the resist layer, a resist pattern is formed on the mask layer 2. Form an opening pattern 3 by dry etching (DE1) the mask layer 2 using the resist pattern as a mask. Then remove the resist pattern.

[0022] At this time, as the dry etching (DE1), it can be performed using a dry etching apparatus such as a RIE (Reactive Ion Etching) apparatus or an ICP (Inductively Coupled Plasma)-RIE etching apparatus which is a dry etching apparatus adopting an inductively coupled plasma method for the discharge form. Also, as the process gas, CHF 3 or CF 4 etc. can be used.

[0023] As an example, using a dry etching apparatus RIE-100C manufactured by Samco, by etching for a predetermined time under the conditions of a CHF 3 gas flow rate of 80 sccm, a pressure of 3 Pa, and an RF power of 90 W, an opening pattern 3 can be formed.

[0024] As a method for removing the resist pattern, for example, it can be removed by a wet process using acetone or an alkaline solution, or a dry process using oxygen plasma.

[0025] Next, as step 4 (Fig. 1 S-4), a through hole 4 is formed by performing through machining on the single crystal silicon substrate 1 under the opening pattern 3 from the surface by dry etching (DE2).

[0026] At this time, the dry etching (DE2) can be performed using an ICP-RIE etching apparatus that employs an inductively coupled plasma in a discharge mode.

[0027] Also, for the process gas, SF 6 , C 4 F 8 , O 2 etc. are used, and by using a Bosch process in which film formation and etching are repeatedly performed cyclically, a highly accurate and vertical through hole 4 can be formed.

[0028] Next, as step 5 (Fig. 1 S-5), the through hole 4 is enlarged by anisotropic wet etching (WE) on the single crystal silicon substrate 1 to form a nozzle taper portion 12 and a straight continuous passage 13 continuous with the nozzle taper portion 12.

[0029] For the anisotropic wet etching (WE) in step 5, an alkaline aqueous solution such as KOH, TMAH (tetramethylammonium hydroxide), or EDP (ethylenediamine pyrocatechol) is used. The nozzle taper portion 12 becomes the

[0111] plane of the Si single crystal, and since the etching rate of the

[0111] plane is extremely slow, a taper is formed at an angle θ of 54.7 degrees as shown in the figure.

[0030] For example, by using a 40 mass% aqueous solution of KOH and performing wet etching at 70°C, a nozzle taper portion 12 and a straight continuous passage 13 as shown in Fig. 1 S-5 and the back view of Fig. 2 can be formed. The nozzle taper portion 12 has the nozzle tip discharge port 11 as the small diameter end. The straight continuous passage 13 is continuous with the large diameter end of the nozzle taper portion 12. The inner surface F1 of the nozzle taper portion 12 is composed of four surfaces. These four surfaces F1 are the

[0111] surfaces. The angle θ formed between the surface of the silicon substrate 1 where the nozzle tip discharge port 11 opens and the surface F1 is 54.7 degrees.

[0031] The inner surface F2 of the straight communication passage 13 is also composed of four surfaces. These four surfaces F2 are the

[0100] surfaces.

[0032] Therefore, the nozzle plate 10A manufactured as described above has a straight communication passage 13 composed of four continuous

[0100] surfaces in the direction in which the diameter of the nozzle taper portion 12 composed of four

[0111] surfaces of single crystal silicon expands.

[0033] According to the method for manufacturing a nozzle plate according to the first embodiment of the present invention as described above, for each nozzle, the through hole 4 formed by penetrating from one opening pattern 3 is enlarged to form the nozzle taper portion 12 and the straight communication passage 13, so that the nozzle plate 10A having a nozzle hole in which the nozzle taper portion 12 and the straight communication passage 13 are continuously aligned without misalignment can be configured. According to the nozzle plate 10A according to the first embodiment of the present invention, since the nozzle taper portion 12 and the straight communication passage 13 communicate without misalignment, the flow of the fluid maintains symmetry and the injection angle is stable. Furthermore, it is difficult for deposits to occur inside the nozzle, and the air release property is also good.

[0034] Furthermore, a protective film 21 may be formed on the nozzle plate 10A as shown in FIG. 3 for long-term use in fluid discharge. In this case, after step 5 (S-5), a step of forming a protective film 21 that covers the surface including the inside of the nozzle taper portion 12 and the inside of the straight communication passage 13 is performed.

[0035] As the protective film 21, a material that does not dissolve upon contact with the ejected fluid (such as ink) can be used. For example, a metal oxide film (tantalum pentoxide, hafnium oxide, niobium oxide, titanium oxide, zirconium oxide, etc.), a metal silicate film containing silicon in the metal oxide film (tantalum silicate, hafnium silicate, niobium silicate, titanium silicate, zirconium silicate, etc.), or the material used for forming the mask layer can be selected and used. Also, an organic film such as polyimide, polyamide, or parylene may be used as the protective film 21. The thickness of the protective film 21 is not particularly limited, but can be, for example, 0.05 to 20 μm.

[0036] 〔Second Embodiment〕 Next, a method for manufacturing a nozzle plate according to a second embodiment of the present invention and the nozzle plate manufactured thereby will be described. The method for manufacturing a nozzle plate according to the second embodiment of the present invention is a method of providing a nozzle straight portion 14 having a nozzle tip discharge port 11 at one end by performing the following steps 6 and 7 between steps 3 and 4 of the first embodiment. Reference diagrams of step 6 (S-6), step 7 (S-7), step 4 (S-4) after step 7, and step 5 (S-5) are shown in FIG. 4.

[0037] Step 1-3 is carried out in the same manner as in the first embodiment. Next, as step 6 (FIG. 4 S-6), the single crystal silicon substrate 1 under the opening pattern 3 is deeply processed by dry etching (DE3) from the surface to form a hole portion 5. The dry etching (DE3) in this step can be carried out in the same manner as the dry etching (DE2) in step 4. However, the etching is terminated when the length of the planned nozzle straight portion 14 is dug down, and it is not penetrated.

[0038] Next, as step 7 (FIG. 4 S-7), a mask layer 6 is formed on the side wall of the hole portion 5. The mask layer 6 of this process can be formed of the same material and in the same way as the mask layer 2 in Process 2. Similar to Process 3, the mask layer at the bottom of the hole 5 is removed by resist patterning and dry etching (DE4). Note that there is no problem in forming the mask layers 2 and 6 in Processes 2 and 7 on both the front and back surfaces of the silicon substrate 1 by thermal oxidation or the like. However, when forming on both surfaces, it is necessary to remove the mask layer at the bottom of the through hole 4 at least before Process 5. If the mask layer at the bottom of the through hole 4 remains, the etching solution will stay inside the through hole 4 during the anisotropic wet etching in the subsequent Process 5, and H 2 gas will also stay, resulting in a delay in the progress of etching and shape variations.

[0039] Subsequently, Process 4 (Fig. 4 S-4) is carried out in the same manner as the first one above, and then Process 5 (Fig. 4 S-5) is carried out. In Process 4 (Fig. 4 S-4), the bottom of the hole 5 is dug deeper to form the through hole 4. In Process 5 (Fig. 4 S-5), the exposed part of the Si under the mask layer 6 in the through hole 4 is enlarged to form the nozzle taper part 12 and the straight communication path 13 that communicate with the nozzle straight part 14.

[0040] According to the manufacturing method of the second embodiment above, a nozzle plate 10B having a nozzle straight part 14 of a desired length at the nozzle tip can be manufactured. One end of the nozzle straight part 14 is the nozzle tip discharge port 11, and the other end is the small-diameter end of the nozzle taper part 12. In the nozzle plate 10B, similar to the nozzle plate 10A in the first embodiment, the taper angle θ is 54.7 degrees, the four inner surfaces F1 of the nozzle taper part 12 are

[0111] planes, and the four inner surfaces F2 of the straight communication path 13 are

[0100] planes.

[0041] According to the manufacturing method of the nozzle plate according to the second embodiment of the present invention described above, similar to the first embodiment, for each nozzle, the through hole 4 formed through one opening pattern 3 is enlarged to form the nozzle taper portion 12 and the straight communication passage 13. Therefore, it is possible to configure a nozzle plate 10B having a nozzle hole in which the nozzle taper portion 12 and the straight communication passage 13 are continuously connected without misalignment. According to the manufacturing method of the nozzle plate according to the second embodiment of the present invention, the side wall of the hole portion 5 is protected by the mask layer 6 and is not eroded by the anisotropic wet etching (WE) in step 5 (FIG. 4 S-5). Therefore, the nozzle straight portion 14 can be formed, and the nozzle straight portion 14 and the nozzle taper portion 12 can also be continuously connected without misalignment. According to the nozzle plate 10B according to the second embodiment of the present invention, similar to the first embodiment, the nozzle taper portion 12 and the straight communication passage 13 are continuously connected without misalignment. Further, the nozzle straight portion 14 and the nozzle taper portion 12 are also continuously connected without misalignment. Therefore, the flow of the fluid maintains symmetry and the injection angle is stable. Furthermore, stagnation is less likely to occur inside the nozzle, and the defoaming property is also good. According to the nozzle plate 10A according to the second embodiment of the present invention, since the nozzle straight portion 14 is continuously connected to the nozzle taper portion 12 without misalignment, the injection angle is further stabilized.

[0042] Furthermore, similar to the first embodiment, a protective film 22 may be formed on the nozzle plate 10B as shown in FIG. 5. In this case, after step 5 (S-5), a step of forming a protective film 22 that covers the surface including the inside of the nozzle straight portion 14, the inside of the nozzle taper portion 12, and the inside of the straight communication passage 13 is performed.

[0043] The nozzle tip discharge port 11 in step 3 in the first and second embodiments described above may have a circular or polygonal pattern as long as it can discharge. This is because neither shape affects the connection between the nozzle taper portion 12 and the straight communication passage 13. After step 5 in the above-described first and second embodiments, the mask layer 2 may or may not be removed. This is because it has no effect on the connection between the nozzle taper portion 12 and the straight communication passage 13. Also, after step 5 in the above-described first and second embodiments, the crystal plane F3 shown in FIGS. 6 and 7 appears on the back side of the single crystal silicon substrate 1. However, since it has no effect on the connection between the nozzle taper portion 12 and the straight communication passage 13, there is no problem using it as it is. However, there is also no problem performing grinding or the like from the back surface to thin the nozzle plate and eliminate the portion of the crystal plane F3. Note that FIG. 7 corresponds to A2 - A2 in FIG. 6 and shows the case of the second embodiment. The cross-sectional views of FIGS. 1 and 4 correspond to the A1 - A1 cross-section shown in FIGS. 2 and 6.

[0044] 〔Fluid ejection head〕 The nozzle plates (10A, 10B) described above are applied as the nozzle plate (110) of a fluid ejection head (101) as disclosed below. Hereinafter, a configuration example of an inkjet head is disclosed as a configuration example of the fluid ejection head.

[0045] (Configuration example of inkjet head) FIG. 8 is a cross-sectional view of the inkjet head (101) as viewed from the side (-X direction side). FIG. 8 shows a cross-section of the inkjet head (101) on a plane including four nozzles (N) included in four nozzle rows.

[0046] The inkjet head (101) is composed of a head chip (102), a common ink chamber (170), a support substrate (180), a wiring member (103), a drive unit (104), and the like.

[0047] The head chip (102) is configured to eject ink from the nozzles (N). In FIG. 8, a plurality of, in this case four, plate-shaped substrates are laminated. The lowermost substrate in the head chip (102) is the nozzle plate (110, a nozzle forming member). The nozzle plate (110) is provided with a plurality of nozzles (N) having the structure according to the present invention, and ink can be ejected from the openings of the nozzles (N) (corresponding to the above-mentioned "nozzle tip ejection port 11") substantially perpendicularly to the exposed surface (ink ejection surface (101a)) of the nozzle plate (110). On the side opposite to the ink ejection surface (101a) of the nozzle plate (110), a pressure chamber substrate (120, a chamber plate), a spacer substrate (140), and a wiring substrate (150) are adhesively laminated in order upward (in the Z direction in FIG. 8). Hereinafter, each of these substrates, namely the nozzle plate (110), the pressure chamber substrate (120), the spacer substrate (140), and the wiring substrate (150), will also be referred to as laminated substrates (110, 120, 140, 150), etc.

[0048] These laminated substrates (110, 120, 140, 150) are provided with ink flow paths communicating with the nozzles (N), and the openings are formed on the exposed side (+Z direction side) surface of the wiring substrate (150). A common ink chamber (170) is provided on the exposed surface of the wiring substrate (150) so as to cover all the openings. The ink stored in the ink chamber forming member (not shown) of the common ink chamber (170) is supplied from the openings of the wiring substrate (150) to each nozzle (N).

[0049] Note that in the nozzle plate (110) shown in FIG. 8, detailed descriptions of the nozzle taper portion and the straight communication path in the nozzle (N) are omitted.

[0050] In the middle of the ink flow path, pressure chambers (121, ink storage parts) are provided. The pressure chamber (121) is provided so as to penetrate the pressure chamber substrate (120) in the vertical direction (Z direction). The upper surface of the pressure chamber (121) is constituted by a diaphragm (130) provided between the pressure chamber substrate (120) and the spacer substrate (140). To the ink in the pressure chamber (121), a pressure change is applied by the deformation of the diaphragm (130) and the pressure chamber (121) due to the displacement (deformation) of the piezoelectric element (160) in the storage part (141) provided adjacent to the pressure chamber (121) via the diaphragm (130). By applying an appropriate pressure change to the ink in the pressure chamber (121), the ink in the ink flow path is discharged as droplets from the nozzles (N) communicating with the pressure chamber (121).

[0051] The support substrate (180) is joined to the upper surface of the head chip (102) and holds an ink chamber forming member (not shown) of the common ink chamber (170). The support substrate (180) is provided with an opening having substantially the same size and shape as the opening on the lower surface of the ink chamber forming member (not shown). The ink in the common ink chamber (170) is supplied to the upper surface of the head chip (102) through the opening on the lower surface of the ink chamber forming member and the opening of the support substrate (180).

[0052] The wiring member (103) is, for example, an FPC (Flexible Printed Circuits) or the like and is connected to the wiring of the wiring substrate (150). The piezoelectric element (160) is displaced by a drive signal transmitted through this wiring to the wiring (151) and the connection part (152, conductive member) in the storage part (141). The wiring member (103) is drawn out through the support substrate (180) and connected to the drive part (104).

[0053] The drive part (104) receives a control signal from the control part of the inkjet recording apparatus, power supply from the power supply part, etc., and outputs an appropriate drive signal for the piezoelectric element (160) to the wiring member (103) according to the ink discharge operation and non-discharge operation from each nozzle N. The drive part (104) is constituted by an IC (Integrated Circuit) or the like.

[0054] According to the fluid ejection head as described above, since the nozzle plates 10A and 10B having nozzle holes in which the nozzle taper portion 12 and the straight communication passage 13 are continuous without misalignment are provided, the flow of fluid (such as ink) maintains symmetry and the ejection angle is stabilized. Further, stagnation is less likely to occur inside the nozzle, and the air release property is also good. Since the ejection angle is stable and ejection failure is less likely to occur, the image quality of the inkjet recording apparatus can be improved.

[0055] 〔Example〕 Examples and comparative examples of the present invention are disclosed below. <Example 1> Example 1 is an example according to the above-described first embodiment. A reference diagram is shown in FIG. 9. In step 1 (FIG. 9 S-1), a single crystal silicon wafer (1) with a crystal orientation of the

[0100] plane and a thickness of 200 μm was prepared. In step 2 (FIG. 9 S-2), a 2-μm-thick oxide film was formed as the mask layer 2 on the single crystal silicon wafer (1) by thermal oxidation. In step 3 (FIG. 9 S-3), a square opening pattern with a side length of 20 μm was formed on the oxide film (2) using a positive photoresist. Thereafter, etching was performed using a CHF 3 gas in a RIE (Reactive Ion Etching) apparatus to form a square opening pattern 3 with a side length of 20 μm in the oxide film (2) according to the resist opening pattern. Thereafter, it was immersed in acetone to remove the photoresist. In step 4 (FIG. 9 S-4), etching was performed by a Bosch process using SF6 and C4F8 gases in a Si deep etching apparatus to form a through hole 4 with a diameter of 20 μm in the single crystal silicon wafer (1) with a thickness of 200 μm. In step 5 (FIG. 9 S-5), the oxide film 7 on the back surface of the single crystal silicon wafer (1) was removed by a RIE apparatus and immersed in a 40 wt%·80 °C KOH aqueous solution, and etching was performed until the width of the straight communication passage 13 became 60 μm to form the nozzle taper portion 12 and the straight communication passage 13. After that, 10 nozzle plates (10A) were obtained from a single-crystalline silicon wafer (1) using a dicing saw, and each nozzle plate was fabricated to have 2,000 nozzle holes. Using the nozzle plates, 10 inkjet heads (101) were fabricated. As a result of measuring the droplet angles at a droplet velocity of 6 m / s for 10 heads × 2,000 nozzles with an injection inspection machine, the angles were in the range of -0.2 degrees to 0.2 degrees, and there were no problems with the injection angles.

[0056] <Comparative Example 1> After the same steps 1 to 4 as in Example 1 above, the following steps were performed to fabricate the nozzle plate of Comparative Example 1. The oxide film at the bottom of the through hole 201 was removed (Fig. 10 T-1), and the substrate was immersed in a 40 wt% KOH aqueous solution at 80 °C for etching to process the diameter of the straight communication path 202 to be 60 μm (Fig. 10 T-2). Then, an oxide film 205 was formed on the inner walls of the communication paths 202 and 203 by thermal oxidation (Fig. 10 T-3), and the oxide film 204 on the back surface was removed by an RIE apparatus to form an opening with a diameter of 60 μm (Fig. 10 T-4). A straight communication path 206 was processed from the back surface to the straight communication path 202 by dry etching (Fig. 10 T-5), and the oxide film 205 was removed using hydrofluoric acid (Fig. 10 T-6) to obtain the nozzle plate 200 of Comparative Example 1. After that, 10 inkjet heads were fabricated in the same manner as in Example 1, and as a result of measuring the droplet angles at a droplet velocity of 6 m / s for 10 heads × 2,000 nozzles, the angles were in the range of -1.0 degrees to 1.2 degrees, and the injection angles deteriorated compared to Example 1.

[0057] <Example 2> Example 2 is an example according to the second embodiment described above. In step 6 (Fig. 4 S-6), after step 3 (Fig. 1 S-3), etching was performed by a Bosch process using SF 6 , C 4 F 8 gas to form a hole portion 5 with a depth of 20 μm. In Step 7 (Fig. 4 S-7), a 0.5-μm thick oxide film (6) was formed on the wafer (1) by thermal oxidation. Subsequently, the oxide film on the bottom surface of the hole 5 with a depth of 20 μm was removed using an RIE apparatus. At this time, since the etching of the oxide film on the bottom surface of the hole 5 proceeded ahead of that on the side wall of the hole 5, only the oxide film on the side wall of the hole 5 remained. After that, ten inkjet heads were fabricated by applying the nozzle plate (10B) fabricated through Steps 4 and 5. Similarly, the droplet angles at a droplet velocity of 6 m / s for 10 heads × 2000 nozzles were measured, and the results showed that the angles were in the range of -0.2 degrees to 0.2 degrees, indicating no problem with the ejection angle.

[0058] <Protective Film Durability Test> For ten nozzle plates each fabricated in the same manner as in Example 1 and Comparative Example 1, Ta which serves as a protective film against ink 2 O 5 was deposited by CVD method. These nozzle plates were immersed in the ink for alkaline printing, and an accelerated test was conducted at 60°C for 8 weeks (equivalent to about 2 years at 25°C). As a result, there was no problem with the nozzle plates of Example 1, but erosion of Si was confirmed at the joints between the straight communication channels 202 and 206 in eight of the nozzle plates of Comparative Example 1.

[0059] Although the embodiments of the present invention have been described above, these embodiments are shown by way of example, and the present invention can be implemented in various other forms. Without departing from the gist of the invention, components can be omitted, replaced, or changed.

Industrial Applicability

[0060] The present invention can be used for the manufacturing method of the nozzle plate According to the method and can be utilized.

Explanation of Reference Numerals

[0061] 1 Single-crystalline silicon substrate 2 Mask layer 3 Opening pattern 4 Through-hole 5 Hole 6 mask layer 10A, 10B nozzle plate 11 nozzle tip discharge port 12 nozzle taper section 13 straight connecting passage 14 nozzle straight section 21 protective film 22 protective film

Claims

1. A method for manufacturing a nozzle plate of a fluid ejection head, which manufactures a nozzle plate having at least a nozzle taper portion and a straight communication passage in a nozzle hole by going through the following steps 1, 2, 3, 6, 7, 4, and 5 in this order. Step 1: A step of preparing a single crystal silicon substrate having a crystal orientation of the surface being the [100] plane. Step 2: A step of uniformly forming a mask layer on the surface of the single crystal silicon substrate. Step 3: A step of forming an opening pattern in the mask layer. Step 6: A step of forming a hole portion by deeply digging the single crystal silicon substrate under the opening pattern from the surface by dry etching. Step 7: A step of forming a mask layer on the side wall of the hole portion. Step 4: A step of forming a through hole by penetrating the single crystal silicon substrate under the opening pattern from the surface by dry etching. Step 5: A step of forming a nozzle taper portion and a straight communication passage continuous with the nozzle taper portion by expanding the through hole by anisotropic wet etching with respect to the single crystal silicon substrate.

2. The method for manufacturing a nozzle plate according to claim 1, wherein after step 5, a step of forming a protective film that covers the surface including inside the nozzle taper portion and inside the straight communication passage is performed.

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