JP2009202457A - Method for manufacturing liquid ejection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording head that can be stably manufactured by preventing the occurrence of defective patterning due to the destruction of a protection film, and a method for manufacturing the same. <P>SOLUTION: When patterning of a soluble solid layer to be a fluid channel is performed so as to make the soluble solid layer to be in a shape of the fluid channel, the solid layer existing under an orifice formed later is removed by patterning to form a space that is to be filled with a protection film, thereby preventing the occurrence of defective patterning. That is, a volume of the solid layer under the orifice to be a cause of defective patterning in etching is reduced so that occurrence of a defect is suppressed. In addition, by forming the space to be filled with the protection film, a filling amount of the protection film is increased. As a result, a strength of the film capable of preventing the protection film from being destroy in the etching can be obtained. It is clear that a liquid ejection head capable of preventing the occurrence of defective patterning can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  An ink jet recording head applied to an ink jet recording method (liquid jet recording method) generally includes a fine ink discharge port (hereinafter referred to as an orifice), a flow path, and a liquid discharge energy generating portion provided in a part of the flow path. There are several. A method of manufacturing an ink jet recording head is disclosed in Patent Document 1 or Patent Document 2.

  In the method of manufacturing an ink jet recording head disclosed in Patent Document 2, an ink flow path pattern is formed by a soluble solid layer on a Si substrate on which an ink discharge pressure generating element is formed. Next, on the ink flow path pattern, a flow path forming member containing an epoxy resin and a cationic photopolymerization initiator serving as an ink flow path wall is formed, and an orifice is formed on the ink discharge pressure generating element by photolithography. Next, using an etching solution, the Si substrate is removed by etching using an anisotropic etching method to form an ink supply port, and after elution of the solid layer through the ink supply port, a flow that becomes an ink flow path wall is formed. The path forming member is cured.

Examples of the etching solution used in the anisotropic etching method include alkali-based etching solutions that are disclosed in Patent Document 2, such as TMAH and KOH, which cause an etching rate difference depending on crystal planes. At this time, a protective film is formed in advance to protect the device surface formed on the Si substrate from the etching solution. The protective film is preferably one that has excellent alkali resistance in alkaline etching, does not chemically attack the functional element, and can be easily removed after etching. For example, a cyclized rubber resin or wax Etc. In particular, a cyclized rubber resin is particularly preferable because it can be coated at room temperature and has excellent resistance to an alkaline etching solution.
JP-A-6-286149 JP 2000-351214 A

  However, in the method for manufacturing an ink jet recording head disclosed in Patent Documents 1 and 2, a defect may occur in the solid layer forming the liquid path due to the stress generated when the flow path forming member is cured. In particular, the defect generated below the discharge port grows when hydrogen gas generated during the etching of the Si substrate permeates the protective film, which may destroy the protective film and cause defective patterning.

  The defect of the solid layer is caused by the stress generated in the step of forming the ink discharge port in the flow path forming member, that is, the heat process after the exposure of the flow path forming member (post exposure bake (PEB) process). It seems that

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to provide an ink jet recording head capable of stable production and a method for manufacturing the same, in which the occurrence of patterning defects due to protective film destruction is suppressed.

The method of manufacturing a liquid discharge head according to the present invention includes a discharge port for discharging a liquid, a flow path communicating with the discharge port, a recording element for discharging the liquid from the discharge port, In a method of manufacturing a liquid discharge head having a liquid supply port communicating with the flow path from the opening on the lower surface of the silicon substrate,
Forming a recording element on a silicon substrate;
Forming a first protective film covering the recording element;
Forming a dissolvable solid layer occupying a portion to be a flow path on the first protective film;
Forming a flow path forming member covering the solid layer;
Forming a discharge port at a position of the flow path forming member facing the recording element;
Removing a region of the solid layer located under the discharge port to form a through-hole that reaches the first protective layer;
Forming a second protective film that covers the flow path forming member and fills the inside of the through hole;
Forming an etching mask on the lower surface of the silicon substrate;
Etching from a surface that is not protected by the etching mask, and forming a liquid supply port that reaches the solid layer from the lower surface of the silicon substrate through the first protective film;
Removing the second protective film;
Removing the solid layer from the silicon substrate via the liquid supply port and the discharge port;
Curing the flow path forming member;
A method for manufacturing a liquid discharge head, comprising:

  According to the method for manufacturing an ink jet recording head of the present invention, it is possible to stably produce an ink jet recording head that suppresses occurrence of patterning failure due to destruction of a protective film.

  The inventor has intensively studied to solve the problems in the prior art described above. As a result, when the dissolvable solid layer that becomes the flow path is patterned into the flow path shape, the solid layer existing below the discharge port to be formed later is removed by patterning to form a space for filling the protective film. Thus, it has been found that the occurrence of patterning defects can be suppressed.

  In other words, by reducing the volume of the solid layer below the discharge port that causes patterning failure during etching, the occurrence of defects is reduced, and further, the amount of filling of the protective film is reduced by forming a space for filling the protective film. To increase. As a result, it has been found that a film strength that prevents destruction of the protective film during etching can be obtained, and an ink jet recording head that suppresses the occurrence of patterning defects can be obtained.

On the upper surface of the silicon substrate of the present invention, a discharge port for discharging a liquid, a flow channel communicating with the discharge port, a recording element for discharging the liquid from the discharge port, and a flow channel from the opening on the lower surface of the silicon substrate A liquid discharge head having a liquid supply port communicating with the above has at least the following manufacturing steps.
(1) A step of forming a recording element on a silicon substrate.
(2) A step of forming a first protective film covering the recording element.
(3) A step of forming a dissolvable solid layer that occupies a portion serving as a flow path on the first protective film.
(3) A step of forming a flow path forming member that covers the solid layer.
(4) A step of forming the discharge port at a position facing the recording element of the flow path forming member.
(5) The process of removing the area | region located under the said discharge outlet of a solid layer, and forming the through-hole which arrives at a 1st protective layer.
(6) A step of forming a second protective film that covers the flow path forming member and fills the through hole.
(7) A step of forming an etching mask on the lower surface of the silicon substrate.
(8) A step of etching from the surface not protected by the etching mask to form a liquid supply port that reaches the solid layer from the lower surface of the silicon substrate through the first protective film.
(9) A step of removing the second protective film.
(10) A step of removing the solid layer from the silicon substrate through the liquid supply port and the discharge port.
(11) A step of curing the flow path forming member.

Since the discharge port and the protective film filling space which is a through hole provided below the discharge port of the solid layer are connected, it is preferable that the diameter of the discharge port and the diameter of the protective film filling space are the same, Since the discharge port and the protective space are formed by different processes, there may be a slight misalignment. For this reason, it is preferable that the diameter of the discharge port is larger than the diameter of the protective film filling space, when the diameter of the protective film filling space is y μm and the positional accuracy of the mask aligner to be used is x μm. It is preferably (y × (0.5) ^1/2 ) μm or more and (y−2x) μm or less.

  In addition, the diameter of the discharge port and the protective film filling space is the diameter in the case of a circle, and the maximum distance between two points on the contour of the cross section when it is not a circle.

  When the discharge port and the protective film filling space are formed using a photolithography method and an etching method, the diameter is determined by the alignment accuracy of the mask aligner to be used.

  The solid layer is preferably a positive photosensitive material, and more preferably polymethylisopropenyl ketone as the positive photosensitive material.

  Further, the flow path forming member is preferably a cationic polymerization compound of an epoxy resin.

  Furthermore, the second protective film is preferably a cyclized rubber-based coating material.

(Example)
A method of manufacturing a liquid discharge head using an electrothermal conversion element as the liquid discharge pressure generating element of the embodiment will be described with reference to the drawings. In this embodiment, an electrothermal conversion element is used as the memory element, but an element such as a heater can be used.

  A plurality of electrothermal conversion elements 2 were formed on a substrate 1 made of Si single crystal having a crystal axis (100), and then a protective layer 4 made of a silicon oxide film having a thickness of 10 μm was formed on the entire surface. In order to protect the protective layer 4 from cavitation, a cavitation protective layer 5 made of Ta was formed on the protective layer 4 covering the electrothermal conversion element 2. A back surface protective film 3 made of a silicon oxide film is formed on the surface of the substrate 1 facing the surface on which the protective layer 4 is formed (see FIG. 1A). In addition to the silicon oxide film, a silicon-based insulating film such as a silicon nitride film or a silicon oxynitride film can be used for the protective layer 4.

  The electrothermal conversion element 2 is connected to an electrode (not shown) for inputting a control signal for operating the electrothermal conversion element 2.

Next, a polyetheramide layer is formed on the protective layer 4 by spin coating, heated at 100 ° C. for 30 minutes, then heated at 250 ° C. for 1 hour to evaporate the coating solvent, and a layer having a thickness of 2.0 μm. I made it. Thereafter, a novolak positive resist was applied and patterned on the polyetheramide layer, and the polyetheramide layer was patterned by O ₂ ashing using the novolac positive resist as a mask. Thereafter, the novolak positive resist used as a mask was peeled off to form an adhesion layer 6 made of polyetheramide (see FIG. 1B).

Subsequently, a film in which polymethylisopropenyl ketone is dissolved in a suitable solvent is formed by spin coating and baked at 120 ° C. for 6 minutes to form a flow path pattern 7 having a thickness of 15 μm. (See FIG. 1C). Thereafter, using an exposure apparatus UX3000 (trade name) manufactured by Ushio Electric Co., Ltd., exposure / development was performed with an energy of 15 J / cm ² to form a flow path pattern 7. At this time, polymethyl isopropenyl ketone existing below the discharge port formed later was patterned in the same shape as the discharge port to form a protective film filling space 8 having a diameter of 13 μm (see FIG. 1D).

Although the diameter of the protective film filling space 8 is preferably equal to the diameter of the discharge port 10 described later, it is necessary to consider the positional accuracy (x) μm of the mask aligner to be used. In consideration of misalignment of the mask, when the diameter of the discharge port (y) μm and the position accuracy of the mask aligner (x) μm, the surface area of the protective filling space is 50% of the area of the discharge port y × It is preferable to set it to (0.5) ^1/2 μm or more and (y−2x) μm or less.

  Thereafter, a flow path forming member 9 composed of 100 parts of an epoxy resin, 2 parts of a cationic polymerization initiator, and 5 parts of an additive was formed (see FIG. 1 (e)). Thereafter, exposure and development were performed using a mask (not shown) with a mask aligner MPA-600 (trade name) manufactured by Canon Inc. to form a discharge port 10 having a diameter of 16 μm in the flow path forming member 9 ( (Refer FIG.1 (f)).

  The electrothermal conversion element 2 and the discharge port 10 are arranged substantially in a straight line.

  As the epoxy resin, EHPE3150 (trade name) manufactured by Daicel Chemical Industries, Ltd., and SP-172 (trade name) manufactured by Adeka Corporation was used as the cationic polymerization initiator. As an additive, SILQUEST A-187 (trade name) manufactured by Nissho Corporation was used.

  Subsequently, after forming the protective film forming material by spin coating, the protective film forming material was dried at 80 ° C. to 120 ° C. to form the etching protective film 11.

  A back surface protective film 3 is formed on the back surface of the substrate 1 (the surface opposite to the surface on which the protective layer 4 is formed). The liquid supply port 12 was formed by performing anisotropic etching of Si using the back surface protective film 3 as a mask (see FIG. 2A).

  Subsequently, after removing the back surface protective film 3 exposed on the bottom surface of the liquid supply port 12, the flow path pattern 7 is removed, and further, the flow path forming member 9 is heated at 200 ° C. for 1 hour, An ejection head was obtained (see FIG. 2B).

  In the case of the prior art, the protective film filling space 8 of the present invention is not formed in the flow path pattern 7. Therefore, the diagram corresponding to FIG. 2A of the present invention is as shown in FIG.

  In addition, as shown in Table 1, when the manufacturing method provided with the protective film filling space of the present example is compared with the conventional manufacturing method, the patterning failure due to the protective film destruction is obtained by using the manufacturing method of the example. It was confirmed that the occurrence of was suppressed.

It is explanatory drawing which shows the manufacturing method of the liquid discharge head of this invention. It is explanatory drawing which shows the manufacturing method of the liquid discharge head of this invention.

Explanation of symbols

1 Substrate 2 Recording element (electrothermal conversion element)
DESCRIPTION OF SYMBOLS 3 Back surface protective film 4 Protective layer 5 Cavitation protective film 6 Adhesion layer 7 Flow path pattern 8 Protective film filling space 9 Flow path component 10 Discharge port 11 Etching protective film 12 Ink supply port

Claims (7)

On the upper surface of the silicon substrate, a discharge port for discharging the liquid, a flow channel communicating with the discharge port, a recording element for discharging the liquid from the discharge port, and an opening on the lower surface of the silicon substrate to the flow channel A liquid discharge head having a liquid supply port communicating therewith,
Forming a recording element on a silicon substrate;
Forming a first protective film covering the recording element;
Forming a dissolvable solid layer occupying a portion to be a flow path on the first protective film;
Forming a flow path forming member covering the solid layer;
Forming a discharge port at a position of the flow path forming member facing the recording element;
Removing a region of the solid layer located under the discharge port to form a through-hole that reaches the first protective layer;
Forming a second protective film that covers the flow path forming member and fills the inside of the through hole;
Forming an etching mask on the lower surface of the silicon substrate;
Etching from a surface that is not protected by the etching mask, and forming a liquid supply port that reaches the solid layer through the first protective film from the lower surface of the silicon substrate;
Removing the second protective film;
Removing the solid layer from the silicon substrate via the liquid supply port and the discharge port;
And a step of curing the flow path forming member.   The method of manufacturing a liquid discharge head according to claim 1, wherein a diameter of the discharge port is larger than a diameter of the through hole. The diameter of the through hole is (y × (0.5) ^1/2 ) μm or more and (y−2x) μm or less, where y μm is the diameter of the discharge port and x μm is the positional accuracy of the mask aligner used. The method of manufacturing a liquid ejection head according to claim 2, wherein the liquid ejection head is provided.   The method for manufacturing a liquid discharge head according to claim 1, wherein the solid layer is made of a positive photosensitive material.   The method for manufacturing a liquid discharge head according to claim 2, wherein the solid layer is made of polymethylisopropenyl ketone.   The method for manufacturing a liquid discharge head according to claim 1, wherein the flow path forming member is formed of a cationic polymerization compound of an epoxy resin.   The method of manufacturing a liquid ejection head according to claim 1, wherein the second protective film is a cyclized rubber-based coating material.

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