JP2015036202A - Method of manufacturing ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an ink jet head which can prevent generation of a residue on a nozzle surface.SOLUTION: In a first thermal oxidation film forming process, a first thermal oxidation film is formed on a first silicon substrate before forming a nozzle. In a first junction process, a second silicon substrate is joined to a surface of the first silicon substrate with the first thermal oxidation film formed. In a nozzle forming process, a nozzle is formed by etching a nozzle forming position of the first silicon substrate to the first thermal oxidation film from an opposite surface side opposite to the junction surface which is joined to the second silicon substrate. In a second junction process, a flow channel substrate having a flow channel of ink including a pressure chamber communicating with the nozzle is joined to an opposite surface side of the first silicon substrate. In a substrate removing process, the second silicon substrate is removed from the first silicon substrate. In a thermal oxidation film removing process, the first thermal oxidation film is removed from the first silicon substrate.

Description

  The present invention relates to a method for manufacturing an inkjet head having a nozzle for discharging liquid.

  An ink jet head of an ink jet recording apparatus has a nozzle plate on which a plurality of nozzles for discharging ink are formed. The nozzle plate is formed using an SOI (silicon on insulator) substrate (see Patent Document 1). The SOI substrate is a bonded substrate obtained by bonding a handle layer substrate, which is a double-side polished silicon substrate having a thermal oxide film formed on the outer surface, and a device layer substrate, which is a silicon substrate.

  In the manufacturing process of the nozzle plate (inkjet head), the device layer substrate of the SOI substrate is etched from the surface opposite to the bonding surface to be bonded to the handle layer substrate to form nozzles on the device layer substrate. At this time, the thermal oxide film (also referred to as a BOX layer) of the SOI substrate functions as an etching stopper. Next, after the flow path substrate and the vibration plate are sequentially joined on the device layer substrate, a piezoelectric element is formed on the vibration plate. The device layer substrate functions as a nozzle plate by removing the handle layer substrate and the thermal oxide film from the device layer substrate by dry etching. Further, the bonding surface of the device layer substrate (nozzle plate) is a nozzle surface on which nozzle openings are formed.

JP 2011-156873 A

  However, when forming the SOI substrate, the handle layer substrate is bonded to the nozzle surface (bonding surface) of the device layer substrate, so that the nozzle surface adheres to particles and the like during bonding, and stress and distortion due to pressure heating during bonding. It will be damaged due to such. As a result, when the handle layer substrate and the thermal oxide film are removed from the device layer substrate by dry etching, a residue is generated on the nozzle surface. Since this residue cannot be removed by the dry etching process, there is a problem that the residue finally remains on the nozzle surface. This residue can be removed by wet etching, but in this case, the etching solution enters the nozzle, which may cause problems with particles in the subsequent process and damage to other layers. Arise.

  The objective of this invention is providing the manufacturing method of the inkjet head which can prevent generation | occurrence | production of the residue of a nozzle surface.

  An inkjet head manufacturing method for achieving an object of the present invention includes: a first thermal oxide film forming step of forming a first thermal oxide film on a first silicon substrate before forming a nozzle for discharging a liquid; A first bonding step of bonding the second silicon substrate to the surface of the silicon substrate on which the first thermal oxide film is formed, and a bonding surface for bonding the nozzle of the first silicon substrate to the second silicon substrate; Are etched from the opposite opposite surface side to the first thermal oxide film, and a flow path substrate having a flow path for ink including a nozzle forming step for forming a nozzle and a pressure chamber communicating with the nozzle is formed on the first silicon substrate. A second bonding step for bonding to the opposite surface side, a substrate removing step for removing the second silicon substrate from the first silicon substrate, and a thermal oxide film removing step for removing the first thermal oxide film from the first silicon substrate. Have.

  According to the present invention, when the first silicon substrate and the second silicon substrate are bonded, the bonding surface of the first silicon substrate is caused by adhesion of particles or the like at the time of bonding or stress or distortion due to pressure heating. Damage is prevented.

  Prior to the first bonding step, there is a second thermal oxide film forming step for forming a second thermal oxide film on the outer surface of the second silicon substrate. In the first bonding step, the first thermal oxide film is formed. Preferably, the bonding surface of the first silicon substrate and the surface of the second silicon substrate on which the second thermal oxide film is formed are bonded. As a result, warpage of the bonded substrate formed by bonding the first silicon substrate and the second silicon substrate is prevented.

  In the thermal oxide film removal step, it is preferable to remove the first thermal oxide film by dry etching. As in the case where the wet etching process is performed, the etching liquid enters the flow path from the nozzle, the flow path is etched, the first silicon substrate or the like is damaged, or the etching liquid enters the flow path. As a result, the generation of particles and residues on the joint surface is prevented.

  In the thermal oxide film removing step, dry etching treatment is preferably performed using a gas containing hydrogen. By using a gas containing hydrogen for dry etching, the etching residue prevention effect is improved. Moreover, since the gas containing hydrogen has a high selection ratio with the underlying first silicon substrate, the accuracy of the nozzle diameter is improved.

  After the thermal oxide film removing process, it is preferable to have a cleaning process for cleaning the bonding surface of the first silicon substrate. Thereby, the adhesiveness of the water-repellent film in the subsequent process is improved, and the durability of the joint surface is improved.

  In the cleaning process, it is preferable to clean the bonding surface by dry etching. In the case of wet etching, there is damage to the flow path and the piezoelectric element due to the etching solution, but in the case of dry etching, there is no such damage, and the etching solution that has entered the flow path is a post process. There is no problem of particles and the like due to coming out. Further, by performing the cleaning process immediately after the thermal oxide film removing step, the yield can be improved and the cost can be reduced.

  In the substrate removal step, it is preferable to remove the second silicon substrate by dry etching. Thereby, since the etching stop at the first thermal oxide film can be performed with high accuracy, the yield is improved and the accuracy of the nozzle diameter is improved.

  In the first thermal oxide film forming step, a first thermal oxide film is formed on the outer surface of the first silicon substrate.

  Between the first joining step and the nozzle forming step, there is a thickness adjusting step for adjusting the thickness of the first silicon substrate to a thickness corresponding to the length of the nozzle. Thereby, the length of the nozzle can be adjusted.

  The first silicon substrate is a silicon substrate having a plane orientation of (100), and the nozzle forming step performs crystal anisotropic etching from the opposite surface side to the first thermal oxide film to form the first thermal oxide film. A nozzle having a taper surface that gradually tapers is formed. Thereby, the nozzle which has a taper surface can be formed.

  According to another aspect of the present invention, there is provided a method of manufacturing an inkjet head, comprising: a bonded substrate formed by bonding a first silicon substrate and a second silicon substrate before forming a nozzle for discharging a liquid; In the bonding substrate in which the first thermal oxide film is previously formed on the bonding surface of the first silicon substrate bonded to the second silicon substrate, the nozzle formation position of the first silicon substrate is determined from the opposite surface side opposite to the bonding surface. The first thermal oxide film is etched to form a nozzle, and a flow path substrate having an ink flow path including a pressure chamber communicating with the nozzle is bonded to the opposite side of the first silicon substrate. A two-bonding step, a substrate removing step of removing the second silicon substrate from the first silicon substrate, and a thermal oxide film removing step of removing the first thermal oxide film from the first silicon substrate.

  The ink jet head manufacturing method of the present invention can prevent the generation of a residue on the nozzle surface.

It is sectional drawing of an inkjet head. It is a process flow of the manufacturing process of an inkjet head. It is explanatory drawing for demonstrating a 1st thermal oxide film formation process. It is explanatory drawing for demonstrating a 1st joining process. It is explanatory drawing for demonstrating a grinding / polishing process. It is explanatory drawing for demonstrating a SOI substrate thermal oxide film formation process. It is explanatory drawing for demonstrating a nozzle formation process. It is sectional drawing of the nozzle substrate formed at the nozzle formation process. It is explanatory drawing for demonstrating a flow-path board | substrate formation process. It is explanatory drawing for demonstrating a 2nd joining process. It is explanatory drawing for demonstrating a piezoelectric element formation process. It is explanatory drawing for demonstrating a handle layer removal process. It is explanatory drawing for demonstrating a BOX layer removal process. It is a front view of the nozzle surface after a BOX layer removal process. It is explanatory drawing for demonstrating the comparative example which forms a thermal oxide film in a handle layer board | substrate. It is explanatory drawing for demonstrating the 1st joining process of a comparative example. It is explanatory drawing for demonstrating the grinding and grinding | polishing process of a comparative example. It is a front view of the nozzle surface after the BOX layer removal process in a comparative example. It is a process flow of the nozzle substrate preparation process included in the manufacturing process of the inkjet head of 2nd Embodiment. It is explanatory drawing for demonstrating the 1st thermal oxide film formation process and 2nd thermal oxide film formation process of 2nd Embodiment. It is explanatory drawing for demonstrating the 1st joining process of 2nd Embodiment. It is explanatory drawing for demonstrating the grinding / polishing process of 2nd Embodiment. It is the schematic of an inkjet recording device. It is the schematic of an inkjet head. It is a block diagram which shows the electric constitution of an inkjet recording device.

[Overall configuration of inkjet head]
As shown in FIG. 1, the inkjet head 10 includes a nozzle plate 13, a flow path substrate 17 having an ink flow path 16 including a pressure chamber 15, a vibration plate 18, a thermal oxide film 19, a piezoelectric element 20, It is comprised including.

  The nozzle plate 13 is a silicon substrate on which a plurality of nozzles 22 are formed. The nozzle 22 is configured by a tapered surface 22b that gradually tapers toward the nozzle opening 22a. Since each nozzle 22 is formed so as to penetrate the nozzle plate 13, the thickness of the nozzle plate 13 becomes the length of the nozzle 22. The nozzle opening 22 a is opened on the nozzle surface (joining surface) 13 a side of the nozzle plate 13. The nozzle surface 13a is subjected to water repellent treatment in order to stabilize the ink (liquid) ejection direction and improve the ejection performance.

  The flow path substrate 17 is a silicon substrate provided on the surface opposite to the nozzle surface 13 a of the nozzle plate 13. The flow path substrate 17 constitutes a side wall portion of the pressure chamber 15. The flow path substrate 17 is formed with a flow path 16 that guides ink supplied from an ink tank (not shown) to the pressure chamber 15. For convenience of explanation, the flow path substrate 17 is simply illustrated in the drawing, but the flow path substrate 17 may have a structure in which a plurality of substrates are stacked.

  The diaphragm 18 constitutes the top surface of the pressure chamber 15 (upper surface in FIG. 1). A piezoelectric element 20 is formed on the vibration plate 18. The piezoelectric element 20 includes a lower electrode 26, a piezoelectric film 27, and an upper electrode 28, and is deformed by application of a driving voltage. As the piezoelectric element 20 is deformed, the diaphragm 18 is deformed and the volume of the pressure chamber 15 is reduced, so that pressure is applied to the ink in the pressure chamber 15. Thereby, ink is ejected from the nozzle 22.

[Manufacturing Process of Inkjet Head of First Embodiment]
Next, a manufacturing process (hereinafter simply referred to as a head manufacturing process) 30 of the above-described ink jet head 10 will be described using the process flow of FIG. 2 and the explanatory diagrams of FIGS. 3 to 13. In order to prevent the drawing from becoming complicated, only the manufacturing process of ink ejection elements for one channel, which is a unit of recording elements of the inkjet head 10, is illustrated.

  The head manufacturing process 30 is roughly divided into a nozzle substrate preparation process 32, a nozzle formation process 33, a flow path substrate formation process 34, a second bonding process 35, a piezoelectric element formation process 36, and a handle layer removal process (substrate). A removal step) 37, a BOX layer removal step (thermal oxide film removal step) 38, a cleaning treatment step 39, and a water repellent treatment step 40.

  In the nozzle substrate preparation step 32, an SOI substrate 49 (bonding substrate, see FIG. 4) that forms the basis of the nozzle substrate 55 (see FIG. 8) is formed. The nozzle substrate 55 is obtained by forming the nozzles 22 on the SOI substrate 49 and includes the nozzle plate 13. The nozzle substrate preparation process 32 includes a first thermal oxide film formation process 32A, a first bonding process 32B, a grinding / polishing process (thickness adjustment process) 32C, and an SOI substrate thermal oxide film formation process 32D. Yes.

  As shown in FIG. 3, in the first thermal oxide film forming step 32A, a thermal oxide film (first thermal oxide film) is formed on the outer surface of a device layer substrate (first silicon substrate) 45 which is a bare silicon substrate having a plane orientation (100). Film) 46 is formed. The thermal oxide film 46 is formed, for example, by subjecting the device layer substrate 45 to wet oxidation treatment or dry oxidation treatment. Since this thermal oxide film 46 is used as an etching stopper layer in the nozzle forming step 33, the film thickness of the thermal oxide film 46 may be determined in accordance with the selection ratio of silicon used as the material of the device layer substrate 45. .

  The device layer substrate 45 is formed of, for example, boron-doped P-type silicon, and has a resistance value of 1 to 100 Ωcm (preferably 5 to 10 Ωcm) and a thickness of 625 μm if the substrate size is 6 inches. use. Further, the device layer substrate 45 has a polished surface on the polished surface to be bonded to a handle layer substrate 47 described later. The device layer substrate 45 finally becomes the nozzle plate 13.

  In the first bonding step 32B, the device layer substrate 45 and the handle layer substrate (second silicon substrate) 47 are bonded. The handle layer substrate 47 is a double-side polished bare silicon substrate. In the first bonding step 32B, first, the device layer substrate 45 and the handle layer substrate 47 are cleaned. Here, for example, RCA cleaning known as wet cleaning [RCA-1 cleaning (SC-1 cleaning), RCA-2 cleaning (SC-2 cleaning)] is performed. Finally, the natural thermal oxide film is removed, and the surfaces of both substrates 45 and 47 are terminated with hydrogen.

Further, the device layer substrate 45 and the handle layer substrate 47 may be subjected to plasma cleaning. When plasma cleaning is performed, OH groups are generated at a high density on the surfaces of both the substrates 45 and 47, and the both substrates 45 and 47 are bonded by hydrogen bonding. In this case, bubbles are generated at the bonding interface due to H ₂ O molecules generated from OH groups. However, since there is SiO ₂ (thermal oxide film 46), H ₂ O molecules are absorbed by SiO ₂ and are bonded at the bonding interface. Can prevent voids.

As shown in FIG. 4, the bonding method in the first bonding step 32B includes direct bonding and plasma-assisted direct bonding. For example, when direct bonding is performed, first, temporary bonding is performed in which the polishing surface on which the thermal oxide film 46 of the device layer substrate 45 is formed and the polishing surface of the handle layer substrate 47 are overlapped in the atmosphere. OH groups are generated on the surfaces of the two substrates 45 and 47 after cleaning, and the two substrates 45 and 47 are temporarily joined by hydrogen bonding between the OH groups. Thereafter, when both the substrates 45 and 47 are heated to several hundred degrees Celsius, H ₂ O molecules are removed from the OH groups and the substrates 45 and 47 are bonded with oxygen. ) Diffuses into the silicon atoms to form bonds between silicon atoms. Sufficient bonding strength can be obtained by heating the substrates 45 and 47 to 1000 degrees or more. Thereby, the SOI substrate 49 is formed.

  Further, a thermal oxide film 46 formed on a bonding surface (hereinafter simply referred to as a bonding surface) bonded to the handle layer substrate 47 of the device layer substrate 45 becomes a BOX (Buried Oxide: buried insulating film) layer 46a. The BOX layer 46a corresponds to the first thermal oxide film of the present invention. The bonding surface of the device layer substrate 45 finally becomes the nozzle surface 13a.

  As shown in FIG. 5, in the grinding / polishing step 32C, the device layer substrate 45 is ground and polished from the opposite surface opposite to the bonding surface (the upper surface in the figure, hereinafter simply referred to as the opposite surface). Thus, the thickness of the device layer substrate 45 corresponding to the length of the nozzle 22 is adjusted. Specifically, the device layer substrate 45 is ground with a coarser (eg, # 200) grinder to the remaining 100 μm before reaching the target thickness, and then finished with a finer (eg, # 5000) polishing member. I do. Finally, a CMP (Chemical Mechanical Polishing) process is performed on the device layer substrate 45. The thickness of the device layer substrate 45 (that is, the length of the nozzle 22) is adjusted to about 10 to 1000 μm, for example, and is adjusted to 50 μm in this embodiment.

  In the SOI substrate thermal oxide film forming step 32 </ b> D, wet oxidation processing or dry oxidation processing is performed on the SOI substrate 49 after the grinding / polishing processing to form a thermal oxide film 51 on the entire surface of the SOI substrate 49. Thus, all the steps of the nozzle substrate preparation step 32 are completed.

  As shown in FIG. 7A, in the nozzle forming step 33, first, a resist mask forming process for forming a resist mask 53 on the thermal oxide film 51 on the opposite surface side of the device layer substrate 45 is performed by patterning or the like. In the resist mask 53, a resist opening 53a is formed at a position corresponding to a position where the nozzle 22 is formed (hereinafter simply referred to as a nozzle forming position) on the device layer substrate 45. Note that a method for forming the resist mask 53 is a well-known technique, and a specific description thereof is omitted here.

  As shown in FIG. 7B, in the nozzle forming step 33 after the resist mask forming process, the thermal oxide film 51 on the device layer substrate 45 is etched using the resist mask 53 as a mask. This etching process is, for example, a wet etching process using hydrofluoric acid or the like. Thereby, the shape of the resist opening 53a is transferred to the thermal oxide film 51, and the thermal oxide film opening 51a is formed at a position corresponding to the nozzle formation position of the thermal oxide film 51. The resist mask 53 is removed from the thermal oxide film 51 after the etching process.

  As shown in FIG. 7C, in the nozzle formation step 33 after the etching process, the nozzle formation position of the device layer substrate 45 is changed from the opposite surface side toward the BOX layer 46a using the thermal oxide film 51 as a mask. A crystal anisotropic etching process for isotropic etching is performed.

  The crystal anisotropic etching process is performed by a wet etching apparatus using KOH or the like as an etching solution. As described above, since the plane orientation of the device layer substrate 45 is (100), the device layer substrate 45 has 111 planes having an angle of about 56.7 ° with respect to the opposite plane. Here, the etching rate of single crystal silicon varies greatly depending on the plane orientation (crystal orientation), and the etching of the 111 plane hardly proceeds with respect to the 100 plane. The BOX layer 46a functions as an etching stopper that stops crystal anisotropic etching.

  By subjecting the nozzle formation position of the device layer substrate 45 to crystal anisotropic etching from the opposite surface side to the BOX layer 46a, a substantially quadrangular pyramid tapered surface 22b that gradually tapers toward the BOX layer 46a at the nozzle formation position. Is formed. In the present embodiment, a tapered surface 22b having a taper shape of about 56.7 ° is obtained. As a result, the nozzle 22 is formed at the nozzle formation position of the device layer substrate 45.

  As described above, in the present embodiment, a substrate having a resistance value of 1 to 100 Ωcm is used as the device layer substrate 45, but the resistance value generally affects the etching rate. A non-doped high resistance product (1000 to 20000 Ωcm) has a high etching rate, and a highly doped low resistance product (0.0001 to 0.1 Ωcm) has a low etching rate. “1 to 100 Ωcm” products have a large circulation in the market and can be obtained at low cost. In addition, since the etching rate of the “1 to 100 Ωcm” product is stable, the amount of undercut is reduced, and the nozzle diameter (the diameter of the nozzle opening 22a) can be increased.

  As shown in FIG. 8, in the nozzle formation step 33 after the crystal anisotropic etching process, for example, a thermal oxide film removing process for removing the thermal oxide films 46 and 51 on the outer surface of the SOI substrate 49 is performed by a wet etching process. .

  Thus, the nozzle forming step 33 is completed, and the nozzle 22 is formed on the SOI substrate 49, whereby the nozzle substrate 55 is generated.

  As shown in FIG. 9, in the flow path substrate forming step 34, the flow path substrate 17 is formed by etching the silicon substrate or stacking after etching a plurality of silicon substrates.

  As shown in FIGS. 10A and 10B, in the second bonding step 35, the flow path substrate 17 is bonded to the opposite surface side of the device layer substrate 45, and the device layer substrate 45 of the flow path substrate 17 is bonded. An SOI substrate 58 is bonded to a surface opposite to the facing surface. The joining method in the second joining step 35 is not particularly limited, and various joining methods such as direct joining and plasma-assisted direct joining may be used.

  The SOI substrate 58 includes a device layer substrate 59, the thermal oxide film 19 that is a BOX layer, and a handle layer substrate 61. The SOI substrate 58 is bonded to the flow path substrate 17 so that the device layer substrate 59 is superimposed on the flow path substrate 17. The device layer substrate 59 finally becomes the above-described diaphragm 18. The device layer substrate 59 is formed to have a thickness corresponding to the thickness of the diaphragm 18 by the same method as the above-described grinding / polishing step 32C.

  As shown in FIG. 11, in the piezoelectric element forming step 36, first, the handle layer substrate 61 is removed from the SOI substrate 58 by using various methods such as grinding / polishing processing and dry etching processing. Thereby, the device layer substrate 59 functions as the diaphragm 18. Next, in the piezoelectric element forming step 36, the lower electrode 26, the piezoelectric film 27, and the upper electrode 28 are sequentially formed on the surface (upper surface in the drawing) opposite to the surface facing the vibration plate 18 of the thermal oxide film 19. To form. Thereby, the piezoelectric element 20 is formed on the vibration plate 18. In addition, since the formation method of the piezoelectric element 20 is well-known, specific description is abbreviate | omitted here. Although not shown, a protective film such as a resist is formed on the substrate surface on the piezoelectric element 20 side.

  As shown in FIG. 12, in the handle layer removing step 37, the handle layer substrate 47 of the nozzle substrate 55 is removed by grinding / polishing processing and dry etching processing. Here, the BOX layer 46a of the nozzle substrate 55 is as thin as about 1 μm, and a nozzle opening 22a is formed on the bonding surface of the device layer substrate 45 in contact with the BOX layer 46a. For this reason, it is necessary to stop polishing at the BOX layer 46a at the time of finishing by polishing. At this time, since the piezoelectric element 20 is formed on the substrate surface on the side of the piezoelectric element 20 and a protective film such as a resist is coated for the protection, unevenness and warpage are generated. . As a result, it becomes difficult to stop polishing at the BOX layer 46a during polishing.

Therefore, when the handle layer substrate 47 is removed from the nozzle substrate 55, the handle layer substrate 47 is ground and polished so as to leave about 50 to 100 μm of silicon. Thereafter, it is desirable to remove the remaining silicon by dry etching. In this dry etching process, silicon is etched by generating plasma using a fluorine-based gas and without applying Bias. Among fluorine-based gases, SF ₆ is effective because of its high silicon etching rate. Specifically, the etching rate is 10 to 100 μm / min, and high-speed etching is possible, so that the cost can be reduced. Further, since Bias is not applied, the selection ratio with the BOX layer 46a (silicon oxide film) which is the base can be increased, and the nozzle plate 13 can be highly accurate. Further, since the etching stop at the BOX layer 46a can be performed with high accuracy, the yield is improved and the accuracy of the nozzle diameter is improved.

  As shown in FIG. 13, in the BOX layer removal step 38, the BOX layer 46a is removed from the nozzle substrate 55 by dry etching. Here, the BOX layer 46a can be removed by a wet etching process using hydrofluoric acid or the like. However, if the wet etching process is performed, the etching solution enters the inside of the nozzle 22. For this reason, there is a possibility that the inside of the flow channel 16 is etched by the etching solution, or particles or the like are drawn from the inside of the flow channel 16 when the etching solution that has entered the flow channel 16 comes out in a later process. is there. As a result, the nozzle surface 13a of the nozzle plate 13 is soiled by particles and residues, or the piezoelectric element 20 is damaged. Therefore, processing by dry etching is effective.

Here, when dry etching is performed, if the underlying silicon (device layer substrate 45) is scraped, the thickness of the nozzle plate 13 changes, and further, the thickness of the device layer substrate 45 at the opening of the nozzle 22 changes. And the nozzle diameter will change. The nozzles 22 having different nozzle diameters have different ink discharge amounts, which affects the image quality. Therefore, a CF-based gas is preferably used for dry etching as an etching gas in order to increase the selectivity with the underlying silicon (device layer substrate 45). For example, CF ₄ , CHF ₃ , C ₃ F ₈ , C ₃ F ₆ , C ₄ F ₆ , C ₄ F _8, or the like is used as a gas containing C and F.

Furthermore, it is effective to use a mixture of an inert gas such as Ar or He or a gas such as oxygen or hydrogen. Examples of the mixed gas are Ar / C ₄ F ₈ , CF ₄ / H ₂ , and Ar / C ₄ F ₈ / H ₂ . In particular, the use of a gas containing hydrogen for dry etching improves the etching residue prevention effect. Moreover, since the gas containing hydrogen has a high selection ratio with the underlying silicon (device layer substrate 45), the accuracy of the nozzle diameter is improved.

  When the BOX layer 46a is removed from the nozzle substrate 55 by the dry etching process, the device layer substrate 45 functions as the nozzle plate 13 described above. A nozzle opening 22 a of the nozzle 22 is opened on the nozzle surface 13 a of the nozzle plate 13.

  In the present embodiment, since the thermal oxide film 46 (BOX layer 46a) is formed on the device layer substrate 45 before the device layer substrate 45 and the handle layer substrate 47 are joined, the nozzle surface 13a (device) in a clean state is formed. A thermal oxide film 46 protects the bonding surface of the layer substrate 45. For this reason, the nozzle surface 13a is prevented from being damaged due to adhesion of particles or the like at the time of joining both the substrates 45 and 47 or stress or distortion due to pressure heating. As a result, as shown in FIG. 14, when the BOX layer 46a is removed from the device layer substrate 45 in the BOX layer removing step 38, the original clean nozzle surface 13a appears. Thereby, generation | occurrence | production of a residue on the nozzle surface 13a is prevented.

  In the cleaning processing step 39, the nozzle surface 13a is cleaned by performing a dry etching process on the nozzle surface 13a. In this dry etching process, Ar is used as an etching gas. Thereby, the CF polymer which is a reactive organism attached to the nozzle surface 13a by the dry etching process in the BOX layer removing step 38 can be removed. As a result, the adhesion of the water-repellent film to the nozzle surface 13a is improved in a later step, so that the durability of the nozzle surface 13a is improved. Further, when the wet etching process is performed instead of the dry etching process, the piezoelectric element 20 and the flow path 16 are damaged, but in the case of the dry etching process, there is no such damage. Furthermore, there is no problem that particles or the like are pulled out from the inside of the flow path 16. By performing the cleaning process immediately after the removal of the BOX layer 46a, the yield can be improved and the cost can be reduced.

  In the water repellent treatment step 40, the water repellent treatment is performed on the nozzle surface 13a. This water-repellent treatment is performed by forming a water-repellent film on the nozzle surface 13a or forming the water-repellent structure on the nozzle surface 13a by, for example, sputtering, vapor deposition, CVD, or wet treatment.

  Thus, the entire head manufacturing process 30 is completed, and the inkjet head 10 is completed.

[Effects of Manufacturing Process of Inkjet Head of First Embodiment]
In the comparative example shown in FIGS. 15 to 17, a thermal oxide film forming step for forming a thermal oxide film 63 on the handle layer substrate 47 as shown in FIG. 15, and a device layer substrate 45 and a thermal oxide film as shown in FIG. The SOI substrate 64 is generated through a joining step for joining the handle layer substrate 47 after the formation of 63 and a grinding / polishing step for adjusting the thickness of the device layer substrate 45 as shown in FIG.

  In such a comparative example, since the handle layer substrate 47 is directly bonded to the bonding surface (nozzle surface 13a) of the device layer substrate 45, the bonding surface of the device layer substrate 45 adheres to particles or the like during bonding or is heated under pressure. Damage due to stress and strain caused by For this reason, when the inkjet head 10 is manufactured using the SOI substrate 64, as shown in FIG. 18, when the BOX layer (thermal oxide film 63) is removed from the device layer substrate 45 in the BOX layer removal step 38. Residue (indicated by dots in the figure) due to the above-described damage occurs on the nozzle surface 13a.

  In contrast to such a comparative example, in the present invention, since the thermal oxide film 46 is formed on the device layer substrate 45 and then bonded to the handle layer substrate 47, the bonding surface of the device layer substrate 45 serving as the nozzle surface 13a is used. Can be prevented from being damaged. As a result, when the BOX layer 46a is removed from the device layer substrate 45 by the dry etching process, it is possible to prevent a residue due to damage from being generated on the nozzle surface 13a.

[Manufacturing Process of Inkjet Head of Second Embodiment]
Next, the head manufacturing process of the second embodiment will be described using the process flow of FIG. 19 and the explanatory diagrams of FIGS. 20 to 22. In the head manufacturing process 30 of the first embodiment, the thermal oxide film 46 is formed on the device layer substrate 45. In the head manufacturing process of the second embodiment, both the device layer substrate 45 and the handle layer substrate 47 are thermally oxidized. A film is formed.

  The head manufacturing process of the second embodiment is basically the same as the head manufacturing process 30 of the first embodiment, except that a nozzle substrate preparation process 70 that is partially different from the first embodiment is included. For this reason, the same reference numerals are given to the same functions and configurations as those in the first embodiment, and the description thereof is omitted.

  The nozzle substrate preparation process 70 is the nozzle of the first embodiment except that the second thermal oxide film formation process 32A-1 is performed between the first thermal oxide film formation process 32A and the first bonding process 32B. This is the same as the substrate preparation step 32. Note that the second thermal oxide film formation step 32A-1 may be performed simultaneously with the first thermal oxide film formation step 32A or before the first thermal oxide film formation step 32A.

  As shown in FIG. 20, in the second thermal oxide film forming step 32A-1, a thermal oxide film (second thermal oxide film) is formed on the outer surface of the handle layer substrate 47 in the same manner as in the first thermal oxide film forming step 32A. 63 is formed.

  Next, as shown in FIG. 21, in the first bonding step 32B described above, the device layer substrate 45 formed with the thermal oxide film 46 and the handle layer substrate 47 formed with the thermal oxide film 63 are bonded, An SOI substrate 49-1 is formed. This SOI substrate 49-1 has basically the same configuration as the SOI substrate 49 of the first embodiment except that the thermal oxide film 63 is formed on the handle layer substrate 47.

  As shown in FIG. 22, in the grinding / polishing step 32C, as in the first embodiment, the device layer substrate 45 is ground and polished, and the thickness of the device layer substrate 45 corresponding to the length of the nozzle 22 is adjusted. .

  In the SOI substrate thermal oxide film forming step 32D, although not shown, a thermal oxide film 51 (see FIG. 6) is formed on the entire surface of the SOI substrate 49-1. Thus, all the nozzle substrate preparation process 70 is completed. The steps after the nozzle substrate preparation step 70 are basically the same as the head manufacturing step 30 of the first embodiment except that the thermal oxide film 63 is removed in the BOX layer removal step 38 described above. Detailed description is omitted.

[Effects of Manufacturing Process of Inkjet Head of Second Embodiment]
As described above, in the second embodiment, since the thermal oxide films 46 and 63 are formed on both the device layer substrate 45 and the handle layer substrate 47, the warpage of the SOI substrate 49-1 can be prevented. The reason is that the substrate after bonding has a thermal oxide film on the outside of the device layer substrate 45 and on the outside of the BOX layer 46a and the handle layer substrate 47, so that the warpage is eliminated by adjusting the balance of the thermal oxide film warpage. The Furthermore, in the thermal oxide films of the device layer substrate 45 and the handle layer substrate 47, the thermal oxide film of the device layer substrate 45 is thinned, and the thermal oxide film of the handle layer substrate 47 is thickened, thereby increasing the effect of reducing warpage ( For example, the device layer substrate 45 is 0.1 μm, and the handle layer substrate 47 is 0.9 μm). In this way, after polishing, the thermal oxide film on the device layer substrate 45 is removed, and the thickness of the thermal oxide film on the BOX layer 46a and the handle layer substrate 47 is close, so the balance on both sides of the thermal oxide film is relaxed and warped. Can be reduced. In particular, when the device layer substrate 45 is ground and polished in the grinding and polishing step 32C, the thermal oxide films 46 and 63 are formed on both surfaces of the handle layer substrate 47, so that the handle layer as in the first embodiment is formed. As compared with the case where the thermal oxide film 46 is formed on one side of the substrate 47, the warpage of the SOI substrate 49-1 can be surely prevented. Thereby, the yield of the inkjet head 10 can be improved. In addition, the accuracy of the nozzle diameter can be improved.

  Also in the head manufacturing process of the second embodiment, since the thermal oxide film 46 is formed on the device layer substrate 45 and bonded to the handle layer substrate 47, the same effects as those described in the first embodiment are obtained. Is obtained.

[Application example to inkjet recording apparatus]
Next, an application example of the ink jet head manufactured in the head manufacturing process 30 (or the head manufacturing process of the second embodiment is applicable, the same applies hereinafter) to an ink jet recording apparatus will be described.

<Overall configuration>
FIG. 22 is an overall configuration diagram of the inkjet recording apparatus 100. The inkjet recording apparatus 100 shown in FIG. 1 has a recording medium conveyance unit 104 that holds and conveys a recording medium 102, and a recording medium 102 that is held by the recording medium conveyance unit 104. ), A printing unit 107 including inkjet heads 106K, 106C, 106M, and 106Y (corresponding to the inkjet head 10) that discharge color inks corresponding to M (magenta) and Y (yellow).

  The recording medium conveyance unit 104 includes an endless conveyance belt 108 in which a large number of suction holes (not shown) are provided in a recording medium holding area where the recording medium 102 is held, and a conveyance roller (drive) around which the conveyance belt 108 is wound. Rollers and driven rollers) 110 and 112 and the back side of the conveyance belt 108 in the recording medium holding area (the surface opposite to the recording medium holding surface on which the recording medium 102 is held) are provided in the recording medium holding area. A chamber 114 that generates a negative pressure in a suction hole (not shown) and a vacuum pump 116 that generates a negative pressure in the chamber 114 are included.

  The carry-in unit 118 into which the recording medium 102 is carried is provided with a pressing roller 120 for preventing the recording medium 102 from floating. A pressing roller 124 is also provided in the discharge unit 122 from which the recording medium 102 is discharged.

  The recording medium 102 carried in from the carry-in unit 118 is applied with negative pressure from the suction holes provided in the recording medium holding area, and is held in the recording medium holding area of the conveyance belt 108.

  On the conveyance path of the recording medium 102, a temperature adjustment unit 126 for adjusting the surface temperature of the recording medium 102 to a predetermined range is provided on the upstream side of the printing unit 107 (upstream side in the recording medium conveyance direction). In addition, a reading device (reading sensor) 128 that reads an image recorded on the recording medium 102 is provided on the rear side of the printing unit 107 (downstream in the recording medium conveyance direction).

  The recording medium 102 carried in from the carry-in section 118 is sucked and held in the recording medium holding area of the conveyor belt 108 and is subjected to temperature adjustment processing by the temperature adjustment section 126, and then image recording is performed in the printing section 107.

  The recording medium 102 on which the image is recorded is ejected from the ejecting unit 122 after the recorded image (test pattern) is read by the reading device 128.

<Configuration of the printing unit>
As shown in FIG. 24, the inkjet heads 106K, 106C, 106M, and 106Y provided in the printing unit 107 are full-line inkjet heads in which a plurality of nozzles are arranged over a length that exceeds the entire width of the recording medium 102. . The inkjet heads 106K, 106C, 106M, and 106Y are manufactured in the head manufacturing process 30 described above.

  The inkjet heads 106K, 106C, 106M, and 106Y have a structure in which a plurality of head modules 140 are connected in the longitudinal direction D1. Each head module 140 has a nozzle surface 144 corresponding to the nozzle surface 13a described above. The nozzle surface 144 is formed with a nozzle row 146a in which a plurality of nozzles 146 (corresponding to the nozzle 22 described above) are arranged along an oblique direction having a certain angle with respect to the longitudinal direction D1, and further, A plurality of the nozzle rows 146a are arranged in the longitudinal direction D1.

  The inkjet heads 106K, 106C, 106M, and 106Y are arranged in this order from the upstream side in the recording medium conveyance direction. A recorded image can be recorded over the entire area of the recording medium 102 by a single-pass method in which the full-line inkjet heads 106K, 106C, 106M, and 106Y and the recording medium 102 are relatively moved once.

  The printing unit 107 is not limited to the above-described form. For example, an inkjet head corresponding to LC (light cyan) or LM (light magenta) may be provided. Further, the arrangement order of the inkjet heads 106K, 106C, 106M, and 106Y can be changed as appropriate.

  In addition, the ink jet recording apparatus 100 includes an ink supply unit (not shown). The ink supply unit includes an ink tank for storing ink supplied to the inkjet heads 106K, 106C, 106M, and 106Y for each color (for each head). Each of the ink tanks for each color and the inkjet heads 106K, 106C, 106M, and 106Y communicate with each other through an ink supply path (not shown).

<Control system configuration>
FIG. 25 is a block diagram illustrating a schematic configuration of a control system of the inkjet recording apparatus 100. The inkjet recording apparatus 100 includes a communication interface 170, a system control unit 172, a conveyance control unit 174, an image processing unit 176, a head drive unit 178, and an image memory 180 and a ROM 182.

  The communication interface 170 is an interface unit that receives raster image data sent from the host computer 184. As the communication interface 170, a serial interface such as USB (Universal Serial Bus) may be applied, or a parallel interface such as Centronics may be applied.

  The system control unit 172 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 100 according to a predetermined program. The system control unit 172 functions as an arithmetic device that performs various calculations, and further functions as a memory controller for the image memory 180 and the ROM 182.

  That is, the system control unit 172 controls each unit such as the communication interface 170 and the conveyance control unit 174, performs communication control with the host computer 184, read / write control of the image memory 180 and ROM 182 and the like. A control signal to be controlled is generated.

  Image data sent from the host computer 184 is taken into the ink jet recording apparatus 100 via the communication interface 170, and is subjected to predetermined image processing by the image processing unit 176.

  The image processing unit 176 has a signal (image) processing function for performing various processing and correction processes for generating a print control signal from the image data. The generated print data (dot data) is transferred to the head drive unit. 178 is a control unit for supplying to 178.

  When required signal processing is performed in the image processing unit 176, the amount of droplets discharged from the inkjet heads 106K, 106C, 106M, and 106Y via the head drive unit 178 based on the print data (halftone image data) ( The droplet ejection amount) and the discharge timing are controlled. The head driving unit 178 may be composed of a plurality of blocks for each head module 140. Thereby, a desired dot size and dot arrangement are realized.

  The conveyance control unit 174 controls the conveyance timing and conveyance speed of the recording medium 102 based on the print data generated by the image processing unit 176. The conveyance drive unit 186 includes a motor that drives the drive roller of the recording medium conveyance unit 104 that conveys the recording medium 102, and the conveyance control unit 174 functions as a driver for the motor.

  The image memory 180 functions as a temporary storage unit that temporarily stores image data input via the communication interface 170, a development area for various programs stored in the ROM 182, and a calculation work area for the CPU (for example, image processing A function as a work area of the unit 176. As the image memory 180, a volatile memory (RAM) capable of sequential reading and writing is used.

  The ROM 182 stores programs executed by the CPU of the system control unit 172, various data necessary for control of each unit of the apparatus, control parameters, and the like, and data is read and written through the system control unit 172. The ROM 182 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used. Alternatively, a removable storage medium that includes an external interface may be used.

  The parameter storage unit 190 stores various control parameters necessary for the operation of the inkjet recording apparatus 100. The system control unit 172 appropriately reads out parameters necessary for control and updates (rewrites) various parameters as necessary.

  The program storage unit 192 is a storage unit that stores a control program for operating the inkjet recording apparatus 100. When the system control unit 172 (or each unit of the device) executes control of each unit of the device, a necessary control program is read from the program storage unit 192, and the control program is appropriately executed.

  The ink jet head manufactured in the head manufacturing process 30 is an ink jet recording apparatus other than the ink jet recording apparatus 100 shown in FIG. 23, for example, an impression cylinder that holds and conveys a recording medium on the outer peripheral surface of the impression cylinder. The present invention can also be applied to an inkjet head of a conveyance type inkjet recording apparatus.

[Others]
In the head manufacturing process 30 of the first embodiment, the thermal oxide film 46 is formed on the outer surface (entire surface) of the device layer substrate 45. For example, the thermal oxide film 46 is formed only on the bonding surface (nozzle surface 13a). It may be formed.

  In each of the above embodiments, the SOI substrates 49 and 49-1 are manufactured in the nozzle substrate preparation steps 32 and 70. However, the SOI substrates 49 and 49-1 are purchased from others and the nozzle formation step 33 and subsequent steps are performed. The present invention can also be applied to the case where the inkjet head 10 is manufactured by appropriately performing each step. The present invention can also be applied to the case where the inkjet head 10 is manufactured by purchasing SOI substrates 49 and 49-1 after the first bonding step 32 </ b> B or after the grinding / polishing step 32 </ b> C from another person.

  In each of the above embodiments, a method for manufacturing an inkjet head used in an inkjet recording apparatus for graphic printing has been described. However, a wiring drawing apparatus for drawing a wiring pattern of an electronic circuit, a manufacturing apparatus for various devices, and a discharge functionality Various shapes and patterns using liquid functional materials such as resist printing equipment using resin liquid as liquid, color filter manufacturing equipment, and fine structure forming equipment that forms fine structures using materials for material deposition The present invention can be applied to a method of manufacturing an inkjet head used in various inkjet recording apparatuses for drawing.

  Furthermore, the present invention is not limited to the above-described embodiments (for example, materials for each substrate and each layer, formation / removal method, etching method, etc.), and various modifications can be made without departing from the spirit of the present invention. Needless to say.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet head, 13 ... Nozzle plate, 17 ... Flow path substrate, 18 ... Vibrating plate, 20 ... Piezoelectric element, 22 ... Nozzle, 30, 70 ... Inkjet head manufacturing process, 32A ... First thermal oxide film forming process, 32A -1 ... second thermal oxide film forming step, 32B ... first bonding step, 33 ... nozzle forming step, 35 ... second bonding step, 36 ... piezoelectric element forming step, 37 ... handle layer removing step, 38 ... BOX layer removing Process, 39 ... Cleaning process

Claims (11)

A first thermal oxide film forming step of forming a first thermal oxide film on the first silicon substrate before forming the nozzle for discharging the liquid;
A first bonding step of bonding a second silicon substrate to a surface of the first silicon substrate on which the first thermal oxide film is formed;
A nozzle forming step of forming the nozzle by etching the nozzle formation position of the first silicon substrate from the opposite surface side opposite to the bonding surface to be bonded to the second silicon substrate to the first thermal oxide film. When,
A second bonding step of bonding a flow path substrate having an ink flow path including a pressure chamber communicating with the nozzle to the opposite surface side of the first silicon substrate;
A substrate removal step of removing the second silicon substrate from the first silicon substrate;
A thermal oxide film removing step of removing the first thermal oxide film from the first silicon substrate;
A method for manufacturing an ink-jet head comprising: Before the first bonding step, a second thermal oxide film forming step of forming a second thermal oxide film on the outer surface of the second silicon substrate,
In the first bonding step, the bonding surface of the first silicon substrate on which the first thermal oxide film is formed is bonded to the surface of the second silicon substrate on which the second thermal oxide film is formed. The method of manufacturing an ink jet head according to claim 1.   The inkjet head manufacturing method according to claim 1, wherein the thermal oxide film removing step removes the first thermal oxide film by a dry etching process.   4. The method of manufacturing an ink jet head according to claim 3, wherein the thermal oxide film removing step performs the dry etching process using a gas containing hydrogen.   5. The method of manufacturing an inkjet head according to claim 1, further comprising a cleaning process step of cleaning the bonding surface of the first silicon substrate after the thermal oxide film removing step. 6.   6. The method of manufacturing an ink jet head according to claim 5, wherein the cleaning process step includes a cleaning process for the bonding surface by a dry etching process.   The method of manufacturing an ink jet head according to claim 1, wherein the substrate removing step removes the second silicon substrate by a dry etching process.   8. The method of manufacturing an ink jet head according to claim 1, wherein the first thermal oxide film forming step forms the first thermal oxide film on an outer surface of the first silicon substrate. 9.   9. The method according to claim 1, further comprising a thickness adjusting step of adjusting a thickness of the first silicon substrate to a thickness corresponding to a length of the nozzle between the first bonding step and the nozzle forming step. The manufacturing method of the inkjet head of description. The first silicon substrate is a silicon substrate having a plane orientation of (100),
In the nozzle forming step, the nozzle having a tapered surface that gradually tapers toward the first thermal oxide film by performing crystal anisotropic etching on the formation position from the opposite surface side to the first thermal oxide film. The method for manufacturing an ink jet head according to claim 1, wherein the ink jet head is formed. A bonding substrate formed by bonding the first silicon substrate and the second silicon substrate before forming the nozzle for discharging the liquid, and on the bonding surface of the first silicon substrate bonded to the second silicon substrate. Etching the nozzle formation position of the first silicon substrate from the opposite surface opposite to the bonding surface to the first thermal oxide film in the bonding substrate on which one thermal oxide film is formed in advance; Forming a nozzle,
A second bonding step of bonding a flow path substrate having an ink flow path including a pressure chamber communicating with the nozzle to the opposite surface side of the first silicon substrate;
A substrate removal step of removing the second silicon substrate from the first silicon substrate;
A thermal oxide film removing step of removing the first thermal oxide film from the first silicon substrate;
A method for manufacturing an ink-jet head comprising:

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