JP5207541B2 - Liquid repellent film forming method, nozzle plate, ink jet head, and electronic apparatus - Google Patents

Description

  The present invention relates to a method for forming a liquid repellent film, a nozzle plate, an ink jet head, and an electronic device, and more particularly to a technique for forming a liquid repellent film having liquid repellency on the surface of a substrate having holes.

  In a recording head (ink jet head) used in an ink jet recording apparatus, if ink adheres to the surface of a nozzle plate (particularly the periphery of the nozzle hole opening) constituting the ink discharge surface, the ink liquid discharged from the nozzle The droplets are affected, resulting in unstable ejection such as variations in the ejection direction of the ink droplets, which causes deterioration in image quality. Therefore, in order to prevent such a problem, a liquid repellent film is provided on the surface (discharge surface) of the nozzle plate on which the nozzle is formed.

  Various techniques for forming a liquid repellent film on the surface of a nozzle plate (hereinafter also referred to as “nozzle forming substrate”) have been proposed so far.

For example, in Patent Document 1, when a liquid repellent film is formed on a nozzle plate on which nozzles are formed, an intermediate layer is provided between the nozzle plate and the liquid repellent film in order to improve adhesion with the nozzle plate. A technique to be introduced is disclosed. Further, in this document, as another aspect, a technique is disclosed in which a step structure is formed in an intermediate layer provided between a nozzle plate and a liquid repellent film, and a liquid repellent film is formed thereon. By forming the step structure in this way, it is possible to prevent the liquid repellent film from being peeled around the nozzles due to paper jam during paper conveyance or wiping during maintenance.
JP 2008-105231 A

  However, in the manufacturing process described in Patent Document 1, there is no etching stop layer when the stepped structure is formed by etching the plasma polymerization film, which is an intermediate layer. In the worst case, there is a problem that the substrate is exposed and the adhesion of the liquid repellent film cannot be improved, and the ejection stability and maintainability are greatly affected.

  The present invention has been made in view of such circumstances, and a liquid repellent film forming method capable of forming a step structure with little variation for each nozzle with high accuracy and improving discharge stability and maintainability. An object is to provide a nozzle plate, an inkjet head, and an electronic apparatus.

  In order to achieve the object, the liquid repellent film forming method according to the present invention (the invention according to claim 1) is a liquid repellent film for forming a liquid repellent film having liquid repellency on the surface of a substrate having holes. A film forming method, comprising: a first plasma polymerized film forming step of forming a first plasma polymerized film on the substrate; a hydrogen plasma processing step of performing a hydrogen plasma process on the first plasma polymerized film; Oxidation treatment using a second plasma polymerized film forming step of forming a second plasma polymerized film made of the same material as the first plasma polymerized film on the one plasma polymerized film and a mask patterned into a predetermined shape Or a step forming step of selectively removing a portion of the second plasma polymerized film corresponding to the opening peripheral portion of the hole by an etching process to form a step structure having a diameter larger than that of the hole; Structure formed An oxidation treatment step of performing oxidation treatment on the surfaces of the first plasma polymerization film and the second plasma polymerization film, and on the surfaces of the first plasma polymerization film and the second plasma polymerization film subjected to the oxidation treatment. And a liquid repellent film forming step for forming the liquid repellent film.

  According to the present invention, the plasma polymerized film (intermediate layer) disposed between the substrate and the liquid repellent film has a two-layer structure of the first plasma polymerized film and the second plasma polymerized film, and is formed on the substrate. Since the plasma resistance of the formed first plasma polymerized film is improved by hydrogen plasma treatment, the second plasma polymerized film made of the same material as the first plasma polymerized film is formed. In the step forming process, the first plasma polymerization film functions as an etching stop layer and completely removes the outer peripheral portion (opening periphery) of the second plasma polymerization film. be able to. As a result, a step structure with little variation for each nozzle can be formed with high accuracy, and discharge stability and maintainability can be improved.

According to a second aspect of the present invention, in the liquid repellent film forming method according to the first aspect, the hydrogen plasma treatment irradiates the first plasma polymerization film with H ₂ plasma.

According to a third aspect of the present invention, in the liquid repellent film forming method according to the first aspect, in the hydrogen plasma treatment, the first plasma polymerization film is irradiated with a plasma of a processing gas containing H ₂ and an inert gas. It is characterized by that.

According to a fourth aspect of the present invention, in the liquid repellent film forming method according to the third aspect, the processing gas contains N ₂ .

  According to a fifth aspect of the present invention, in the liquid repellent film forming method according to the first aspect, the hydrogen plasma treatment is performed by irradiating a plasma of a processing gas containing a substance having H and an inert gas. .

  In order to achieve the above object, the nozzle plate according to the present invention (the invention according to claim 6) is formed by the liquid repellent film forming method according to any one of claims 1 to 5. A liquid film is provided.

  In order to achieve the object, an ink jet head according to the present invention (invention according to claim 7) includes the nozzle plate according to claim 6.

  In order to achieve the above object, an electronic apparatus according to the present invention (the invention described in claim 8) includes the ink jet head described in claim 7.

  According to the present invention, the plasma polymerized film (intermediate layer) disposed between the substrate and the liquid repellent film has a two-layer structure of the first plasma polymerized film and the second plasma polymerized film, and is formed on the substrate. Since the plasma resistance of the formed first plasma polymerized film is improved by hydrogen plasma treatment, the second plasma polymerized film made of the same material as the first plasma polymerized film is formed. In the step forming process, the first plasma polymerization film functions as an etching stop layer and completely removes the outer peripheral portion (opening periphery) of the second plasma polymerization film. be able to. As a result, a step structure with little variation for each nozzle can be formed with high accuracy, and discharge stability and maintainability can be improved.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram illustrating an ink jet recording apparatus according to the present embodiment. As shown in the figure, the inkjet recording apparatus 10 includes a printing unit 12 having a plurality of inkjet heads (hereinafter also simply referred to as “heads”) 12K, 12C, 12M, and 12Y provided for each ink color. , An ink storage / loading unit 14 for storing ink to be supplied to each of the heads 12K, 12C, 12M, and 12Y, a paper feeding unit 18 for supplying the recording paper 16, and a decurling processing unit for removing the curl of the recording paper 16 20, a suction belt conveyance unit 22 that is disposed opposite to the nozzle surface (ink ejection surface) of the printing unit 12 and conveys the recording paper 16 while maintaining the flatness of the recording paper 16, and printing by the printing unit 12 A print detection unit 24 that reads the result, and a paper discharge unit 26 that discharges printed recording paper (printed matter) to the outside.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  In the case of an apparatus configuration using roll paper, a cutter 28 is provided as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. The round blade 28B is arranged on the print surface side with the conveyance path interposed therebetween. Note that the cutter 28 is not necessary when cut paper is used.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  After the decurling process, the cut recording paper 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least a portion facing the nozzle surface of the printing unit 12 and the sensor surface of the printing detection unit 24 is flat. It is configured to make.

  The belt 33 has a width that is greater than the width of the recording paper 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 1, an adsorption chamber 34 is provided at a position facing the nozzle surface of the print unit 12 and the sensor surface of the print detection unit 24 inside the belt 33 spanned between the rollers 31 and 32. Then, the suction chamber 34 is sucked by the fan 35 to be a negative pressure, whereby the recording paper 16 on the belt 33 is sucked and held.

  The power of a motor (not shown) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, so that the belt 33 is driven in the clockwise direction in FIG. The recording paper 16 is conveyed from left to right in FIG.

  Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blowing method of spraying clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Although a mode using a roller / nip transport mechanism instead of the suction belt transport unit 22 is also conceivable, when the print area is transported by a roller / nip, the roller comes into contact with the print surface of the paper immediately after printing, so that the image blurs. There is a problem that it is easy. Therefore, as in this example, suction belt conveyance that does not contact the image surface in the printing region is preferable.

  A heating fan 40 is provided on the upstream side of the printing unit 12 on the paper conveyance path formed by the suction belt conveyance unit 22. The heating fan 40 heats the recording paper 16 by blowing heated air onto the recording paper 16 before printing. Heating the recording paper 16 immediately before printing makes it easier for the ink to dry after landing.

  The printing unit 12 is a so-called full-line type head in which line-type heads having a length corresponding to the maximum paper width are arranged in a direction (main scanning direction) orthogonal to the paper transport direction (sub-scanning direction). Each of the heads 12K, 12C, 12M, and 12Y constituting the printing unit 12 has a plurality of ink discharge ports (nozzles) arranged over a length exceeding at least one side of the maximum size recording paper 16 targeted by the inkjet recording apparatus 10. It is composed of a line-type head (see FIG. 2).

  A head corresponding to each color ink in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side (left side in FIG. 1) along the conveyance direction (paper conveyance direction) of the recording paper 16. 12K, 12C, 12M, and 12Y are arranged. A color image can be formed on the recording paper 16 by ejecting the color ink from each of the heads 12K, 12C, 12M, and 12Y while conveying the recording paper 16.

  Thus, according to the printing unit 12 in which the full line head that covers the entire width of the paper is provided for each ink color, the recording paper 16 and the printing unit 12 are relatively moved in the paper transport direction (sub-scanning direction). It is possible to record an image on the entire surface of the recording paper 16 by performing this operation only once (that is, by one sub-scan). Thereby, high-speed printing is possible and productivity can be improved as compared with a shuttle type head in which the head reciprocates in a direction (main scanning direction) orthogonal to the paper transport direction.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink are added as necessary. May be. For example, it is possible to add a head for ejecting light-colored ink such as light cyan and light magenta.

  As shown in FIG. 1, the ink storage / loading unit 14 has tanks that store inks of colors corresponding to the heads 12K, 12C, 12M, and 12Y, and each tank is connected via a conduit that is not shown. The heads 12K, 12C, 12M, and 12Y communicate with each other. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means, etc.) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. doing.

  The print detection unit 24 includes an image sensor (line sensor or the like) for imaging the droplet ejection result of the print unit 12, and means for checking nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor. Function as.

  The print detection unit 24 of this example is composed of a line sensor having a light receiving element array that is wider than at least the ink ejection width (image recording width) of the heads 12K, 12C, 12M, and 12Y. The line sensor includes an R sensor row in which photoelectric conversion elements (pixels) provided with red (R) color filters are arranged in a line, a G sensor row provided with green (G) color filters, The color separation line CCD sensor includes a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The print detection unit 24 reads the test patterns printed by the heads 12K, 12C, 12M, and 12Y for each color, and detects the ejection of each head. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like.

  A post-drying unit 42 is provided following the print detection unit 24. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  When printing on porous paper with dye-based ink, the weather resistance of the image is improved by preventing contact with ozone or other things that cause dye molecules to break by blocking the paper holes by pressurization. There is an effect to.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined uneven surface shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. ing. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B.

  Although not shown, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

[Head structure]
Next, the structure of the heads 12K, 12C, 12M, and 12Y will be described. Since the structures of the heads 12K, 12C, 12M, and 12Y are common, the head is represented by the reference numeral 50 in the following.

  FIG. 3A is a plan perspective view showing a structural example of the head 50, and FIG. 3B is an enlarged view of a part thereof. FIG. 3C is a perspective plan view showing another structural example of the head 50. 4 is a cross-sectional view (a cross-sectional view taken along line IV-IV in FIGS. 3A and 3B) showing a three-dimensional configuration of the ink chamber unit.

  In order to increase the dot pitch formed on the recording paper surface, it is necessary to increase the nozzle pitch in the head 50. As shown in FIGS. 3A and 3B, the head 50 of this example includes a plurality of ink chamber units 53 including nozzles 51 that are ink droplet ejection holes and pressure chambers 52 corresponding to the nozzles 51. Nozzles that are arranged in a staggered matrix (two-dimensionally), and are thus projected in a row along the head longitudinal direction (main scanning direction perpendicular to the paper transport direction). High density of the interval (projection nozzle pitch) is achieved.

  The form in which one or more nozzle rows are configured over a length corresponding to the entire width of the recording paper 16 in a direction substantially orthogonal to the paper transport direction is not limited to this example. For example, instead of the configuration of FIG. 3A, as shown in FIG. 3C, short head blocks (head chips) 50 ′ in which a plurality of nozzles 51 are two-dimensionally arranged are arranged in a staggered manner. By connecting them together, a line head having a nozzle row having a length corresponding to the entire width of the recording paper 16 may be configured. Although not shown, a line head may be configured by arranging short heads in a line.

As shown in FIG. 4, each nozzle 51 is formed on a nozzle plate 60 that constitutes the ink ejection surface 50 a of the head 50. The nozzle plate 60 is made of, for example, a silicon-based material such as Si, SiO ₂ , SiN, or quartz glass, a metal-based material such as Al, Fe, Ni, Cu, or an alloy containing these, or an oxide such as alumina or iron oxide. It is composed of physical materials, carbon black, carbon-based materials such as graphite, and resin-based materials such as polyimide.

  A liquid repellent film 62 having liquid repellency with respect to ink is formed on the surface of the nozzle plate 60 (the surface on the ink ejection side) to prevent ink adhesion. The method for forming the liquid repellent film 62 will be described in detail later.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and the nozzle 51 and the supply port 54 are provided at both corners on the diagonal line. Each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54. The common flow channel 55 communicates with an ink supply tank (not shown) as an ink supply source, and the ink supplied from the ink supply tank is distributed and supplied to each pressure chamber 52 via the common flow channel 55.

  A piezoelectric element 58 having an individual electrode 57 is joined to a diaphragm 56 that constitutes the top surface of the pressure chamber 52 and also serves as a common electrode. By applying a driving voltage to the individual electrode 57, the piezoelectric element 58 is Deformation causes ink to be ejected from the nozzle 51. When ink is ejected, new ink is supplied from the common channel 55 to the pressure chamber 52 through the supply port 54.

  In this example, the piezoelectric element 58 is applied as a means for generating ink ejection force ejected from the nozzles 51 provided in the head 50. However, a heater is provided in the pressure chamber 52, and the pressure of film boiling caused by heating of the heater is used. It is also possible to apply a thermal method that ejects ink.

  As shown in FIG. 3B, the ink chamber units 53 having such a structure are arranged in a fixed manner along a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. By arranging a large number of patterns in a lattice pattern, the high-density nozzle head of this example is realized.

  That is, with a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. Thus, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having one nozzle row in the sub-scanning direction can be applied.

  Further, the application range of the present invention is not limited to the printing method using the line-type head, and a short head that is less than the length of the recording paper 16 in the width direction (main scanning direction) is scanned in the width direction of the recording paper 16. Printing in the width direction is performed, and when printing in one width direction is completed, the recording paper 16 is moved by a predetermined amount in a direction perpendicular to the width direction (sub-scanning direction), and the recording paper 16 in the next printing area is moved. A serial method in which printing is performed in the width direction and printing is performed over the entire printing area of the recording paper 16 by repeating this operation may be applied.

[Liquid repellent film forming method]
Next, the liquid repellent film forming method according to the present invention will be described.

  FIG. 5 is a process diagram showing an example of a liquid repellent film forming method according to the present invention. Here, as shown in FIG. 5 (i), a liquid repellent film 120 (corresponding to the liquid repellent film 62 in FIG. 4) on the surface (ink ejection surface) side of the nozzle forming substrate 100 (corresponding to the nozzle plate 60 in FIG. 4). ) Will be described.

  In the liquid repellent film forming method shown in FIG. 5, the first plasma polymer film 104 is formed on the surface of the nozzle forming substrate 100 (first plasma polymer film forming process), and the first plasma polymer film 104 is subjected to hydrogen plasma treatment. Performing a step (hydrogen plasma treatment step), forming a second plasma polymer film 106 on the first plasma polymer film 104 (second plasma polymer film forming process), and mask 108 on the second plasma polymer film 106 Forming a mask (mask forming process), performing a process of oxidizing (or etching) the second plasma polymerization film 106 using the mask 108, and removing the mask 108 (mask removing process). ), A process of oxidizing the surfaces (liquid repellent film forming surfaces) of the first and second plasma polymer films 104 and 106 (oxidation process process), and a first process and a process of performing the oxidation process. Constructed from a step of forming a liquid repellent film 120 on the surface of the second plasma polymerization film 104 (liquid repellent film forming step). Details of each step are as follows.

<First plasma film forming step>
First, as shown in FIGS. 5A and 5B, the first plasma polymerization film 104 is formed on the nozzle forming substrate 100 having the nozzle holes 102.

  The constituent material of the nozzle forming substrate 100 is not particularly limited. For example, a silicon-based material, a metal-based material, an oxide material, a carbon-based material, a resin-based material, or the like can be used. In the illustrated example, the cross-sectional shape of the nozzle hole 102 is a funnel shape, but the cross-sectional shape of the nozzle hole 102 is not particularly limited in the practice of the present invention, and various shapes such as a straight shape and a tapered shape are applied. Can do.

  As the constituent material and the formation method (film formation method) of the first plasma polymerization film 104, the materials and methods described in Japanese Patent Application Laid-Open No. 2008-105231 can be preferably used.

  That is, examples of the constituent material of the first plasma polymerization film 104 include silicone materials such as organopolysiloxane and silane compounds such as alkoxysilane. Of these, silicone materials are preferred, and organopolysiloxanes are particularly preferred. By using organopolysiloxane for the first plasma polymerized film 104, it has a structure having a siloxane bond (Si—O) as a skeleton, so that it can be easily combined with the constituent material (silicon-based material, etc.) of the nozzle forming substrate 100 and easily. A plasma polymerized film can be formed.

  Of the organopolysiloxanes, it is preferable to use alkylpolysiloxanes. Since alkylpolysiloxane is a polymer compound, a polymer film can be formed on the nozzle forming substrate 100. In addition, since the polymer has an alkyl group, the polymer structure has little steric hindrance, and a film in which molecules are regularly arranged can be formed. Of the alkylpolysiloxanes, dimethylpolysiloxane is particularly preferable. Since dimethylpolysiloxane is easy to produce, it can be easily obtained. Further, since the reactivity is high, the methyl group can be easily cleaved when the first plasma polymerization film 104 is subjected to an oxidation treatment as will be described later.

  Moreover, as a formation method of the 1st plasma polymerization film | membrane 104, the plasma polymerization method, a vapor deposition method, the process by a silane coupling agent, the process by the liquid material containing a polyorganosiloxane, etc. are mentioned, One of these or Two or more kinds can be used in combination. Among these methods, it is preferable to use a plasma polymerization method.

  In the plasma polymerization method, for example, a substrate (that is, the nozzle forming substrate 100) is installed in a chamber, an electric field is generated in the chamber, a monomer is supplied in a gaseous state together with a carrier gas, and the generated plasma is plasma-polymerized. In this method, a film is formed on the surface of the substrate.

  Since plasma of organopolysiloxane is generated by using the plasma polymerization method, the first plasma polymerization film 104 having a uniform and uniform film thickness can be formed.

  In addition, as said carrier gas (addition gas), argon, helium, nitrogen, etc. can be used, for example.

  The average film thickness of the first plasma polymerization film 104 is preferably about 10 to 1000 nm, and more preferably about 50 to 500 nm. With such a thickness, an optimum alkyl group terminates on the surface of the first plasma polymerized film 104, so that the adhesion of the liquid-repellent film 120 can be improved by an oxidation treatment and a reaction with a metal alkoxide, which will be described later. it can.

<Hydrogen plasma treatment process>
Next, as shown in FIG. 5C, the first plasma polymerization film 104 formed on the nozzle forming substrate 100 is subjected to hydrogen plasma treatment (H ₂ plasma treatment), and the plasma resistance of the first plasma polymerization film 104 is increased. Improve sexiness. Thus, the first plasma polymerization film 104 can function as an etching stop layer in an oxidation process (or etching process) in a step forming process performed later.

  The hydrogen plasma treatment includes the following three types of methods.

(1) H ₂ plasma irradiation (2) Plasma irradiation of processing gas containing H ₂ and inert gas (3) Plasma irradiation of processing gas containing H-containing substance and inert gas Conditions of H ₂ plasma irradiation are as follows: , H ₂ is supplied into the chamber, and the pressure in the chamber is set to a predetermined value, preferably 13.3 MPa (100 mTorr) or less, for example, 6.7 MPa (50 mTorr). In this state, high frequency power is applied to the electrodes, the processing gas is turned into plasma, and the plasma polymerized film is irradiated with H ₂ plasma.

Although the detailed mechanism for improving the plasma resistance is not necessarily clear, the plasma containing H promotes the crosslinking reaction of the first plasma polymerization film 104, or the C—O bond or the C—H bond is changed to the C—C bond. This is thought to strengthen the scientific coupling and improve the plasma resistance. As the substance having H, H ₂ and NH ₃ are preferable because they are easy to handle. For example, the plasma resistance of the first plasma polymerization film 104 can be improved by hydrogen plasma treatment using H ₂ + N ₂ treatment gas.

<Second plasma film forming step>
Next, as shown in FIG. 5D, a second plasma polymerization film 106 is formed on the first plasma polymerization film 104 that has been subjected to the hydrogen plasma treatment.

  At this time, the same material as the constituent material of the first plasma polymerization film 104 described above is used as the constituent material of the second plasma polymerization film 106. By laminating the plasma polymerization films 104 and 106 made of the same material, it is possible to maintain a state in which the adhesion between the plasma polymerization films is high.

  The formation method of the second plasma polymerization film 106 is not particularly limited, but is preferably the same method as the formation method of the first plasma polymerization film 104 described above, and among these, the plasma polymerization method is preferably used. It is done.

  Similar to the first plasma polymerization film 104, the average film thickness of the second plasma polymerization film 106 is preferably about 10 to 1000 nm, and more preferably about 50 to 500 nm. With such a thickness, an optimal amount of alkyl groups terminates on the surface of the second plasma polymerized film 106, so that the adhesion of the liquid repellent film 120 is enhanced by an oxidation treatment described later and a reaction with a metal alkoxide. be able to.

<Mask formation process>
Next, as shown in FIG. 5E, a mask 108 patterned in a predetermined shape is formed on the second plasma polymerization film 106.

  The mask 108 is formed with an opening 112 having a predetermined shape so as to include an outer peripheral portion 110 corresponding to the outer peripheral portion (opening peripheral portion) of the nozzle hole 102 of the second plasma polymerization film 106. In other words, the outer peripheral portion 110 of the second plasma polymerized film 106 is not covered with the mask 108 and is exposed through the opening 112.

  In the illustrated example, the mask 108 is provided with an opening 112 at a position corresponding to each nozzle hole 102, and each opening 112 is formed in a circular shape in which the inner diameter of the nozzle hole 102 is increased. Yes. The shape of the opening 112 of the mask 108 is not particularly limited as long as the outer peripheral portion 110 of the nozzle hole 102 in the second plasma polymerization film 106 is exposed at least, and the outer peripheral portion 110 corresponding to the plurality of nozzle holes 102 is not limited. (For example, a belt-like shape).

  As a constituent material of the mask 108, as long as it has resistance to an oxidation process (or etching process) performed in the next step forming process, that is, a function of blocking energy rays irradiated in the next process. The material is not particularly limited, and examples thereof include materials such as metals such as aluminum, glass (glass having a function of blocking ultraviolet rays), various ceramics, and silicon.

  The method for forming the mask 108 is not particularly limited. For example, a plate-like mask 108 having an opening 112 may be attached to the second plasma polymerization film 106. Specifically, the outer peripheral portion 110 and the opening 112 of the mask 108 are positioned so that the outer peripheral portion 110 of the nozzle hole 102 in the second plasma polymerized film 106 is exposed, and the mask is formed on the second plasma polymerized film 106. 108 may be joined. Further, as another forming method, an evaporation method, a photolithography method, or the like can be used.

  As described above, the peripheral portion 110 and the opening 112 are positioned and the mask 108 is disposed on the second plasma polymerization film 106, whereby the outer peripheral portion 110 exposed from the opening 112 is selectively oxidized. can do.

<Step formation process>
Next, as shown in FIG. 5 (f), the second plasma polymerization film 106 covered with the mask 108 is oxidized to remove the outer peripheral portion 110 of the second plasma polymerization film 106, and the nozzle hole 102 is opened. A step structure 114 having a diameter larger than that of the nozzle hole 102 is formed in the peripheral portion (see FIG. 5G).

  It is described in Japanese Patent Application Laid-Open No. 2008-105231 that when a plasma polymerized film is subjected to an oxidation treatment, the thickness of the plasma polymerized film in the oxidized part is reduced. In this example, such a property is used to selectively remove a portion exposed from the opening 112 of the mask 108 (that is, the outer peripheral portion 110 of the second plasma polymerization film 106). In addition, about the oxidation process, the method similar to the oxidation process performed at the oxidation process process mentioned later is used, and description is abbreviate | omitted here.

When the oxidation treatment is performed on the second plasma polymerized film 106, only the portion immediately below the opening 112 of the mask 108 of the second plasma polymerized film 106, that is, the outer peripheral portion 110 is selectively oxidized by the function of the mask 108 described above. Processing is performed. As a result, the alkyl group terminating at the surface of the portion 110 is cleaved from the Si atom and converted to SiO ₂ . And the film thickness of the 2nd plasma polymerization film 106 in the opening part 112, ie, the 2nd plasma polymerization film 106 in the outer peripheral part 110, decreases. At this time, since the first plasma polymerization film 104 whose plasma resistance has been improved by the hydrogen plasma treatment functions as an etching stop layer, a portion of the second plasma polymerization film 106 that is not covered with the mask 108 (that is, the outer peripheral portion 110). Is completely removed, and a stepped structure 114 having a diameter larger than that of the nozzle hole 102 is formed around the opening of the nozzle hole 102.

  In this embodiment, the oxidation process is applied as a method for removing the outer peripheral portion 110 of the second plasma polymerization film 106, but an etching process may be applied instead of the oxidation process.

<Mask removal process>
Next, as shown in FIG. 5G, the mask 108 is removed from the second plasma polymerization film 106.

  The removal method of the mask 108 differs depending on the type (formation method) of the mask 108. When the plate-shaped mask 108 is used, for example, the mask 108 can be removed by being separated from the second plasma polymerization film 106. Further, when the mask 108 is formed by vapor deposition or photolithography, for example, it may be performed by a method of exposing to oxygen plasma or ozone vapor under atmospheric pressure or reduced pressure, or a method of immersing in a solution or stripping solution of the mask 108. Can do.

<Oxidation process>
Next, as shown in FIG. 5H, an oxidation treatment is performed on the surfaces (liquid repellent film forming surfaces) of the plasma polymerization films 104 and 106 constituting the step structure 114. Specifically, oxidation treatment is performed on the surfaces of the plasma polymerization films 104 and 106 in a processing gas atmosphere having a dew point of −40 to 20 ° C. (preferably −40 to −20 ° C.), and hydroxyl groups and / or adsorbed water are removed. Introduce.

  As a method for the oxidation treatment, a method described in JP-A-2008-105231 can be preferably used.

That is, as an oxidation treatment method, a method of irradiating energy rays such as ultraviolet rays and plasma can be applied. According to this method, since the oxidation treatment can be performed only on the region irradiated with the energy rays, the SiO ₂ conversion can be efficiently performed.

  In particular, in the present embodiment, among the methods of irradiating energy rays, a method of performing oxidation treatment using plasma irradiation is preferable. In the case of using plasma irradiation as the oxidation treatment, examples of gas species that generate plasma include oxygen gas, nitrogen gas, hydrogen, inert gas (argon gas, helium gas, etc.), and one of these. Alternatively, two or more kinds can be used in combination.

The atmosphere for plasma irradiation may be in the air or in a reduced pressure state, but is preferably in the air. As a result, oxygen atoms are efficiently introduced from oxygen molecules existing in the atmosphere almost simultaneously with the bond between the alkyl group and Si being broken, so that polyorganosiloxane can be changed to SiO ₂ more quickly. Can do.

In particular, for plasma irradiation, it is preferable to use oxygen plasma irradiation using a gas containing oxygen gas as a gas species for generating plasma. According to the oxygen plasma irradiation, since the oxygen plasma breaks the bond between the alkyl group and Si and is used for the bond between Si and the oxygen atom, the polyorganosiloxane can be more reliably changed to SiO _2. .

  Further, the plasma irradiation may be performed under any of sealed conditions (for example, in the chamber) or open conditions, but is preferably sealed conditions. Thereby, since the plasma polymerization films 104 and 106 are oxidized in a state where the plasma density is higher, more hydroxyl groups can be introduced into the plasma polymerization films 104 and 106.

<Liquid repellent film forming process>
Next, as shown in FIG. 5I, a liquid repellent film 120 is formed on the surface (liquid repellent film forming surface) of the plasma polymerized films 104 and 106 subjected to the oxidation treatment.

  The liquid repellent film 120 is not particularly limited as long as it can form a siloxane bond with the plasma polymerized films 104 and 106. For example, a metal alkoxide liquid repellent film, a fluorine-containing plasma polymerized film, or a silicone plasma polymerized film. A liquid repellent film or the like can be applied, and among these, a plasma polymerized film such as a fluorine-containing plasma polymerized film or a silicone-based plasma polymerized liquid repellent film is particularly preferable.

  As a method for forming a liquid repellent film composed of a plasma polymerized film, the method described in Japanese Patent Application Laid-Open No. 2004-106203 can be preferably used. That is, the plasma polymerized film (liquid repellent film) can be formed using a conventionally known plasma processing apparatus. As a raw material, a gas obtained by vaporizing a low molecular weight siloxane such as liquid siloxane is used as a raw material gas. If necessary, this raw material gas is mixed with a rare gas such as argon or helium, or a gas having an oxidizing power such as oxygen or carbon dioxide. Thereby, it can laminate | stack on the nozzle formation board | substrate 100 in the state which superposed | polymerized the raw material.

  As described above, the liquid repellent film composed of a plasma polymerized film is formed by using a low molecular weight siloxane (compound having a siloxane bond) as a raw material and plasma polymerizing it, and has excellent resistance to metal salts. It is most suitable as a liquid repellent layer for a nozzle plate for an aqueous pretreatment liquid (metal salt solution) containing the metal salt as an ink flocculant.

  Moreover, as a formation method of a metal alkoxide type liquid repellent film, the method described in Unexamined-Japanese-Patent No. 2008-105231 can be used preferably. That is, it can be performed using various processes such as a liquid phase process and a gas phase process, and among them, the liquid phase process is preferably used, and a liquid repellent film composed of a metal alkoxide is formed by a relatively simple process. Can be formed.

  In this way, as shown in FIG. 5I, the liquid repellent film 120 can be formed on the surface side (ink ejection surface side) of the nozzle forming substrate 100.

  According to the liquid repellent film forming method in the present embodiment, the plasma polymerized film (intermediate layer) disposed between the nozzle forming substrate 100 and the liquid repellent film 120 is the first plasma polymerized film 104 and the second plasma polymerized film 106. The first plasma polymerized film 104 formed on the nozzle forming substrate 100 with a two-layer structure is improved in plasma resistance by hydrogen plasma treatment, and then the first plasma polymerized film 104 made of the same material as the first plasma polymerized film 104 is used. 2 Since the plasma polymerized film 106 is formed, it is possible to maintain a high adhesiveness between the plasma polymerized films 104 and 106, and the first plasma polymerized film 104 functions as an etching stop layer in the step forming process. In addition, the outer peripheral portion 110 of the second plasma polymerization film 106 can be completely removed. As a result, the step structure 114 with little variation for each nozzle hole 102 can be formed around the nozzle opening, and the discharge stability and maintainability can be improved.

  Further, since the surface of the step structure 114 (liquid repellent film forming surface) is composed of plasma polymerized films (plasma polymerized films 104 and 106) of the same material, the liquid repellent film 120 is subjected to oxidation treatment on these surfaces. It is possible to improve the adhesion. On the other hand, when a functional film made of a material different from that of the second plasma polymerization film 106 is provided instead of the first plasma polymerization film 104 as an etching stop layer, the step structure 114 is compared with the above-described conventional technique. Can be formed with high accuracy, but there is a problem that the adhesion of the liquid-repellent film 120 on the surface of the functional film (corresponding to the bottom surface portion of the step structure 114) is deteriorated.

  In the present embodiment, at least two steps (preferably, a first plasma polymerization film formation step, a hydrogen plasma treatment step, a second plasma polymerization film formation step, a step formation step, an oxidation treatment step, and a liquid repellent film formation step) An embodiment in which three or more steps, more preferably all steps) are performed in the same plasma apparatus is preferable. By performing formation of the plasma polymerized film, hydrogen plasma treatment, oxidation treatment, and formation of the liquid repellent film with a common apparatus, it is possible to prevent a decrease in yield and throughput. Thereby, it becomes possible to perform liquid repellent film formation in the consistent production process, and it can improve productivity and reliability.

  The liquid repellent film forming method according to the present invention has been described by way of an example in which a liquid repellent film is formed on a nozzle forming substrate. However, the present invention is not limited to this, and holes such as ink flow paths are formed. The present invention can also be suitably applied to the case where a liquid repellent film is formed on a substrate (structure).

  The liquid repellent film forming method, the nozzle plate, the ink jet head, and the electronic device have been described in detail above, but the present invention is not limited to the above examples, and various improvements can be made without departing from the gist of the present invention. It goes without saying that or may be modified.

Overall configuration diagram showing outline of inkjet recording apparatus FIG. 1 is a plan view of a main part around a printing unit of the ink jet recording apparatus shown in FIG. Plane perspective view showing structural example of head Sectional view along line IV-IV in Fig. 3 Process drawing for demonstrating the liquid-repellent film formation method which concerns on this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device 50 ... Head, 51 ... Nozzle, 52 ... Pressure chamber, 54 ... Ink supply port, 55 ... Common flow path, 58 ... Piezoelectric element, 60 ... Nozzle plate, 62 ... Liquid repellent film, 100 ... Nozzle Forming substrate, 102 ... nozzle hole, 104 ... first plasma polymerized film, 106 ... second plasma polymerized film, 108 ... mask, 114 ... step structure, 120 ... liquid repellent film

Claims (8)

A liquid repellent film forming method for forming a liquid repellent film having liquid repellency on the surface of a substrate having a hole,
A first plasma polymerized film forming step of forming a first plasma polymerized film on the substrate;
A hydrogen plasma treatment step of performing a hydrogen plasma treatment on the first plasma polymerization film;
A second plasma polymerization film forming step of forming a second plasma polymerization film made of the same material as the first plasma polymerization film on the first plasma polymerization film;
Using a mask patterned into a predetermined shape, the portion corresponding to the opening peripheral portion of the hole portion in the second plasma polymerization film is selectively removed by oxidation treatment or etching treatment, and the diameter is larger than that of the hole portion. A step forming step for forming the stepped structure;
An oxidation treatment step of performing an oxidation treatment on the surfaces of the first plasma polymerization film and the second plasma polymerization film in which the step structure is formed;
A liquid repellent film forming step of forming the liquid repellent film on the surfaces of the first plasma polymerized film and the second plasma polymerized film subjected to the oxidation treatment;
A liquid repellent film forming method comprising: In the liquid repellent film forming method according to claim 1,
In the hydrogen plasma treatment, the first plasma polymerization film is irradiated with H ₂ plasma. In the liquid repellent film forming method according to claim 1,
In the hydrogen plasma treatment, the first plasma polymerization film is irradiated with plasma of a treatment gas containing H ₂ and an inert gas. In the liquid repellent film forming method according to claim 3,
The method for forming a liquid repellent film, wherein the processing gas contains N ₂ . In the liquid repellent film forming method according to claim 1,
The hydrogen plasma treatment is performed by irradiating a plasma of a treatment gas containing a substance containing H and an inert gas.   A nozzle plate comprising a liquid repellent film formed by the liquid repellent film forming method according to claim 1.   An ink jet head comprising the nozzle plate according to claim 6.   An electronic apparatus comprising the inkjet head according to claim 7.

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