JP2007160777A - Liquid jet recording head, substrate therefor, and manufacturing method for substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jet recording head which can obtain a good ejection characteristic for a long period of time by suppressing a decrease of coating performance and layer quality even when a layer such as a thermal storage layer formed on a substrate for the liquid jet recording head is thin, and by avoiding effects of particles, and to provide its substrate and its manufacturing method. <P>SOLUTION: The substrate used for the liquid jet recording head which ejects liquid droplets from ejection ports is equipped with a support 1, the thermal storage layer 1b formed on the support 1, heating resistors 2a for generating thermal energy, a pair of electrodes formed on the support 1 to be electrically conductive with the heating resistor 2a, and a protecting layer 4 which covers the pair of electrodes and the heating resistors 2a. The thermal storage layer 1b is comprised of an ECR (electronic cyclotron resonance) sputtering layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid jet recording head that performs recording by discharging a recording liquid from an ejection port using thermal energy, and also relates to a substrate used in the head and a method for manufacturing the same.

  A liquid jet recording method for recording on a recording medium (in many cases, paper) by ejecting and flying droplets of ink or the like from an ejection port using thermal energy is a non-impact recording method. In addition, it has features such as low noise, direct recording on plain paper, and easy color image recording by using multi-color ink, and the structure of the recording device is simple and high density multi-nozzle is achieved. It has the advantage that it can be easily obtained, and can easily obtain a high-resolution and high-speed one, and has been rapidly spreading in recent years.

  FIG. 3 is a vertical sectional view of an essential part of the example of the liquid jet recording head in a plane parallel to the liquid path. As shown in FIG. 3, this liquid jet recording head is generally provided for each of a number of fine ejection ports 7 for ejecting recording liquid such as ink and the ejection ports 7 and communicates with the ejection ports 7. A liquid chamber 6 (not shown) provided in common to each liquid path 6 for supplying a recording liquid to each liquid path 6 and a ceiling portion of the liquid chamber for supplying liquid to the liquid chamber. A liquid supply port (not shown), and a liquid jet recording head substrate 8 having a heating resistor 2a for applying thermal energy to the recording liquid corresponding to each liquid path 6. . The liquid path 6, the discharge port 7, the liquid supply port, and the liquid chamber are integrally formed on the top plate 5.

As shown in FIG. 3, the substrate 8 for a liquid jet recording head is provided with a heating resistance layer 2 made of a material having a volume resistivity of a certain size on a substrate 1. The electrode layer 3 made of a material having good conductivity is laminated. The electrode layer 3 has the same shape as the heat generating resistor layer 2, but a part thereof is missing, and the heat generating resistor layer 2 is exposed in the missing part, and this part becomes the heat generating resistor 2a, that is, the heat generating part. . The electrode layer 3 has two electrodes sandwiching the heating resistor 2a. When a voltage is applied between these electrodes, a current flows through the heating resistor 2a to generate heat. The heating resistors 2 a are formed on the liquid jet recording head substrate 8 so as to be located at the bottoms of the corresponding liquid paths 6 of the top plate 5. Further, the liquid jet recording head substrate 8 is provided with a protective layer 4 so as to cover the electrodes and the heating resistor 2a. The protective layer 4 is provided for the purpose of preventing electrical corrosion and electrical breakdown of the heating resistor 2a and the electrode 3 due to contact with the recording liquid and penetration of the liquid. The protective layer 4 is generally configured using SiO ₂ . Further, an anti-cavitation layer (not shown in FIG. 3) is provided on the protective layer 4. As a method for forming the protective layer 4, various vacuum film forming methods such as a plasma CVD method, a sputtering method, or a bias sputtering method are used.

When silicon is used as the support 1, a heat storage layer made of SiO ₂ is used for the purpose of obtaining better characteristics as the liquid jet recording head substrate 8 so that the heat dissipation and heat storage properties of the support are balanced. Generally, it is provided as the surface of or a part thereof. When the support is a conductor, it is convenient in terms of design and cost to make the heat storage layer also serve as the insulating layer in order to avoid electrical short-circuiting of the wiring. As a method for forming the heat storage layer, a method of thermally oxidizing the surface of the support 1 made of silicon, or various vacuum film forming methods (for example, sputtering, bias sputtering, heat, etc.) on the support 1 are used. There is a method of depositing SiO ₂ by a CVD method, a plasma CVD method, or an ion beam method.

  Further, depending on the configuration of the liquid jet recording head substrate, two layers of wiring may be provided on the substrate in a matrix (a pair of electrodes connected to the heating resistor is one of them). In this case, the wiring layer (electrode) directly connected to the heating resistor layer is a wiring layer farther from the substrate because of the positional relationship with the liquid path. Therefore, the wiring layer closer to the substrate is embedded in the heat storage layer. FIG. 6 is a schematic cross-sectional view showing the configuration of such a liquid jet recording head substrate.

In the substrate for a liquid jet recording head shown in FIG. 6, the heat storage layer 402 is formed by being divided into a first heat storage layer 402a and a second heat storage layer 402b. A first heat storage layer 402a made of SiO ₂ is provided on the silicon substrate 401, and a lower wiring 403 that is a first wiring layer is formed on the first heat storage layer 402a. The first heat storage layer 402 a can be formed by thermal oxidation of the silicon substrate 401. The lower wiring 403 is generally made of aluminum, and is provided, for example, for matrix driving of the heat generating portion. On the other hand, the second heat storage layer 402 b is formed on the upper surface of the first heat storage layer 402 a on which the lower wiring 403 is formed so as to cover the lower wiring 403. The second heat storage layer 402b is composed of SiO _2. Further, similarly to the liquid jet recording head substrate shown in FIG. 3, the heating resistor layer 404, the second wiring layer electrode layer 405, and SiN (silicon nitride) are formed on the second heat storage layer 402b. A protective layer 406 and an anti-cavitation layer 407 are provided. Since the second heat storage layer 402b cannot be formed by thermal oxidation due to the presence of the lower wiring 403, it is formed by a plasma CVD method, a sputtering method, a bias sputtering method, or the like, similarly to the protective layer 406.

  Patent Document 1 describes a basic film configuration of a heat storage layer, a heating resistor, wiring, and a protective film in an inkjet head.

Patent Document 2 describes a configuration in which one of the multilayer wirings for driving the electrothermal conversion element in a divided manner is formed in the heat storage layer. An example is described in which a SiO ₂ film is formed by a CVD method as a heat storage layer.
Japanese Patent Publication No. 63-38306 Japanese Patent Application Laid-Open No. 2-125741

As described above, in the liquid jet recording head substrate, a silicon oxide layer typified by a SiO ₂ layer is used as the heat storage layer. These layers can be classified into the following two types.

  (1) A layer that can be formed by thermal oxidation of a support made of silicon (the heat storage layer 1b in FIG. 3 or the first heat storage layer 402a in FIG. 6).

  (2) Layer that cannot be formed by thermal oxidation of silicon (when protective layer 4 in FIG. 3, second heat storage layer 402b and protective layer 406 in FIG. 6, metal, or the like is a support).

  Here, according to this classification, the problem of formation of these layers will be examined.

(1) Layer that can be formed by thermal oxidation: The layer that can be formed by thermal oxidation is preferably formed by thermal oxidation from the viewpoint of cost and film quality of the obtained film. That is, when formed by various conventional vacuum film forming methods, the film thickness may become non-uniform or the film forming speed may be slow, as will be described later. Further, since dust is easily generated during film formation, the dust may be mixed into the film and become a defect having a diameter of several μm, which may cause destruction due to cavitation. Furthermore, there is a possibility that current leaks from the irregular defects and causes an electrical short circuit. There is also a method of forming a layer made of SiO ₂ on the substrate surface without performing a thermal oxidation process by a spin-on-glass method or a dip pulling method. However, by any of these methods, the film quality is poor, and in order to obtain a good film quality, high-temperature heat treatment is necessary or impurity particles are likely to be mixed in the film, and a SiO ₂ layer having a thickness of about 3 μm that is necessary as a heat storage layer. May not be formed.

(2) Layer that cannot be formed by thermal oxidation: In the case of a layer that cannot be formed by thermal oxidation, the SiO ₂ layer is inevitably formed by a vacuum film-forming method such as plasma CVD, sputtering, or bias sputtering. It will be. In this case, an SiO ₂ layer is formed on the wiring layer, the heat generation resistance layer, and the thermal oxidation layer of polycrystalline silicon, and this layer needs to be well formed in the stepped portion. In addition, since a wiring layer or a heating resistance layer may be further formed on the SiO ₂ layer thus formed, it is desirable that the upper surface side of the step portion is flat. Hereinafter, problems in forming the SiO ₂ layer will be described for each of the plasma CVD method, the sputtering method, and the bias sputtering method.

  In the plasma CVD method, the shape of the film is steep at the step portion of the wiring, the film quality at the step portion of the wiring is not necessarily good, and minute irregularities are likely to occur on the surface of the formed film. May occur. First, the fact that the shape becomes steep at the step portion will be described.

FIG. 7A is a cross-sectional view showing the structure of the step portion of the SiO ₂ film 410 formed on the aluminum wiring (thin film) 409 by the plasma CVD method. When the step portion is formed using the plasma CVD method, the step portion is deeply cut as shown by the arrow A in the figure. For this reason, as shown in FIG. 7B, when the thin film 411 is formed on the SiO ₂ film 410 by vapor deposition, sputtering, or the like, the film does not wrap around the A portion, and thus becomes thinner than the flat portion. When a wiring or the like is formed, the current density increases, which may cause heat generation or disconnection. Further, when patterning the wiring formed on the SiO ₂ film 410, if the normal photolithography technique is used, the resist will be lost at the step portion, and a short circuit between the wirings is likely to occur. FIG. 7C is a view of what is shown in FIG. 7B as viewed from the C direction. A film 411 on the SiO ₂ film 410 (shaded portion in FIG. 7) such as an aluminum wiring is formed along the stepped portion. In the resist patterning, since the resist remains in the SiO ₂ coverage portion, the state of extending along the step is shown. This problem is particularly likely to occur in an interlayer film, that is, a SiO ₂ layer sandwiched between a plurality of wiring layers.

When the SiO ₂ film is formed by the plasma CVD method, for example, the film quality of the stepped portion as shown by B in FIG. When the formed SiO ₂ film is etched with a hydrofluoric acid-based etchant, the flat part film is etched only at a rate 2 to 4 times that of the SiO ₂ film formed by thermal oxidation, whereas the B part film is Since the denseness is low, etching may occur instantaneously. In such a film portion with low density, cracks are likely to occur due to thermal stress of repeated heating and cooling of the heater (heat generating portion), and the function may be easily lost when used as a protective layer. . In addition, a hydrofluoric acid-based etchant may not be used for patterning of a film laminated on the SiO ₂ film, for example, a HfB ₂ film used for a heating resistance layer or a Ta film used as an anti-cavitation layer. is there.

The minute unevenness on the surface of the SiO ₂ film formed by the plasma CVD method will be described. A film formed by plasma CVD generally tends to generate minute irregularities on the surface even when formed on a flat substrate. Since the uneven shape of the SiO ₂ film also remains on the anti-cavitation layer that is in direct contact with the ink, the starting points of foaming (foaming nuclei) are scattered on the heater surface when the ink is foamed on the heater surface. Thus, the stable film boiling phenomenon is difficult to reproduce and the discharge performance may be adversely affected.

  The sputtering method may cause problems in that the shape of the film is steep at the step portion of the wiring, the film quality of the formed film is not very good, and there are many so-called particles. The steepness at the stepped portion is the same as in the case of the plasma CVD method, and therefore the description is omitted. First, the film quality is described.

When the SiO ₂ film is formed by a normal sputtering method (a method in which a SiO ₂ target is sputtered with Ar gas), a dense film cannot be formed unless the substrate temperature is raised to about 300 ° C. However, when the temperature is raised to about 300 ° C., large hillocks may grow on the aluminum layer used for the wiring. In particular, as shown in FIG. 8, when hillocks are generated at the edge portion of the aluminum wiring 409, the substantial film thickness difference in the SiO ₂ film 410 thereon increases, and the coverage as a film deteriorates. That is, cracks are likely to occur at the step portion, and when the ink comes into contact with the electrode from the crack portion, there is a case where electrolytic corrosion occurs. Further, even if the substrate temperature is raised to 300 ° C., the film quality of the stepped portion is not improved, so that there may be a problem in the same point as the film formed by the plasma CVD method.

As a method of forming a film at a low temperature without deteriorating the film quality, there is a method of sputtering a SiO ₂ target in an atmosphere of Ar and H ₂ , but the film quality of the step portion is not improved, and the film of the step portion Since the shape is the same as in the case of FIG. 7A, the same problem as the film formed by plasma CVD occurs. Further, when H ₂ gas is added, the film forming speed decreases (it is considered that the higher the amount of H ₂ added, the lower the speed), and the processing capacity decreases.

In addition, a target, a shield plate, a shutter plate, and the like are provided in the film formation chamber of the sputtering apparatus, and the structure is complicated compared to the reaction chamber of the plasma CVD apparatus. When an insulating film such as SiO ₂ is formed, spark discharge may occur due to charge up or the like. There may be a problem in that scattering of members due to spark discharge or accumulated dust that cannot be removed by complicated maintenance (cleaning) in the film forming chamber accumulates as particles on the substrate. That is, when such dust is taken into the film, it becomes a defect of several μm, and if a heating resistor is formed on the defect, cavitation breakage may occur during ejection. When the substrate is conductive, current leaks from the defective portion and may be electrically short-circuited. For this reason, it cannot be said that it is easy to increase the reliability and durability of the manufactured recording head.

  The bias sputtering method is a method in which high-frequency power is applied also to the substrate side, and the shape of the stepped portion is smoothed by utilizing the sputtering effect by self-bias. Unlike the sputtering or plasma CVD, the stepped portion is flattened well. Easy to do.

FIG. 9 schematically shows the structure of the step when the SiO ₂ layer 410 is formed on the aluminum wiring 409 by the bias sputtering method. From this figure, compared to the case of the plasma CVD method or the like, It can be seen that the step portion is flattened. However, there may be a problem in that particles are likely to be generated as in the normal sputtering method. Also, bias sputtering may have poor film thickness stability.

  The object of the present invention is to prevent the influence of particles by suppressing the deterioration of coverage and layer quality even when the layer is thin, such as a heat storage layer formed on a substrate for a liquid jet recording head. Accordingly, it is an object of the present invention to provide a substrate capable of obtaining good discharge characteristics for a long period of time.

  Another object of the present invention is to provide a method suitable for producing such an excellent substrate for a liquid jet recording head.

  Still another object of the present invention is to provide a liquid jet recording head capable of exhibiting good ejection characteristics for a long period of time.

According to the present invention, there is provided a substrate for use in a liquid jet recording head that discharges droplets from an ejection port,
A support, a heat storage layer formed on the support, a heating resistor for generating thermal energy, and a pair of electrodes formed on the support so as to be electrically connected to the heating resistor;
A protective layer covering the pair of electrodes and the heating resistor,
A substrate for a liquid jet recording head is provided, wherein the heat storage layer comprises an ECR sputter layer.

  The heat storage layer may be formed by laminating a plurality of matrix wiring layers formed on a support via an insulating film, and the insulating layer formed on the wiring layer may be an ECR sputter layer.

  The ECR sputter layer may include silicon oxide.

  The ECR sputter layer may include silicon nitride oxide.

According to the present invention, a support, a heat storage layer formed on the support, a heating resistor for generating thermal energy, and a pair formed on the support so as to be electrically connected to the heating resistor. Electrodes,
In a method for manufacturing a substrate for a liquid jet recording head comprising the pair of electrodes and a protective layer covering the heating resistor,
There is provided a method for manufacturing a substrate for a liquid jet recording head, wherein the heat storage layer is formed by an ECR sputtering method.

  In the above method, the heat storage layer is formed by laminating a plurality of matrix wiring layers formed on a support via an insulating film, and the insulating layer formed on the wiring layer is an ECR sputter layer. Can do.

  In the above method, the ECR sputtered layer may include silicon oxide.

  In the above method, the ECR sputtered layer may include silicon nitride oxide.

According to the present invention, the liquid jet recording head substrate described above;
A liquid path for flowing a recording liquid provided corresponding to a heating resistor provided in the liquid jet recording head substrate; and
There is provided a liquid jet recording head having an ejection port that communicates with the liquid path and ejects a recording liquid.

  According to the present invention, in a layer such as a heat storage layer formed on a substrate for a liquid jet recording head, even if the layer is thin, the covering property and the layer quality are prevented from being deteriorated, and the influence of particles is avoided. A substrate capable of obtaining ejection characteristics with a good period is provided.

  In addition, the present invention provides a method suitable for manufacturing such an excellent substrate for a liquid jet recording head.

  Furthermore, the present invention provides a liquid jet recording head that can exhibit good ejection characteristics for a long time.

  An embodiment in which an ECR (electron cyclotron resonance) sputter layer is disposed between the heating resistor and the pair of electrodes and the support will be described. Hereinafter, a layer disposed between the heating resistor and the pair of electrodes and the support is referred to as a lower layer. An example of the lower layer is a heat storage layer. First, a method for forming the lower layer that is the heat storage layer will be described.

  In the present invention, it is difficult to form a lower layer by thermal oxidation, and in order to reduce energy required for foaming while ensuring heat dissipation of the substrate, several μm (for example, 0.1 μm to 5.0 μm) This is particularly effective when it is necessary to provide a lower layer having a thickness of 2).

  As the support, a polycrystalline silicon support, an alumina support without a glaze layer, a ceramic support such as aluminum nitride, silicon nitride, or silicon carbide, or a metal support such as aluminum, stainless steel, copper, or kovar is used. it can.

When forming the lower layer on the support, a conventional vacuum film forming method in the present invention (sputtering, bias sputtering, plasma CVD, etc.) the SiO ₂ instead of forming in the SiO ₂ by ECR sputtering method Form a film.

Even when a film other than SiO ₂ , such as a silicon nitride film, is provided as a lower layer, the film is formed by ECR sputtering.

First, the ECR sputtering method will be described (reference material: Journal of Precision Engineering, Vol. 66, No. 4, 2000, Takao Amazawa, Hideo Oikawa, Shigeru Kanno, Seitaro Matsuo). In the ECR sputtering method, electrons undergo cyclotron motion due to the interaction between a magnetic field (for example, 875 gauss) and a microwave (for example, 2.45 GHz), and the ionization probability of the sputtering gas increases, and for example, 10 ⁻⁵ to 10 ⁻⁴ Torr (10 ^A stable plasma can be obtained under a high vacuum of ⁻³ to 10 ⁻² Pa). The ions in the plasma flow extracted while maintaining the neutrality of the plasma by the gradient magnetic field are accelerated and collided with a negatively biased target arranged on the way and sputtered. The sputtered neutral particles are ionized in the plasma and accelerated in the direction of the substrate together with the plasma flow to form a film.

  At this time, the energy of the plasma flow is, for example, 10 to 30 eV. One of the features of ECR sputtering is that high-quality thin film formation can be improved. The main reason for this is that thin film growth proceeds in the presence of a large amount of energy-controlled ions. .

When the energy of ions incident on the substrate is about 50 eV or more, the ions enter the substrate, the atoms constituting the substrate are knocked out, or defects are generated in the substrate. May cause problems. On the other hand, when the film is formed only with thermal energy as in the vapor deposition method, the energy of the incident particles is on the order of as low as 0.1 eV, and migration may not be sufficiently performed on the substrate surface. On the other hand, in ECR sputtering, the energy of irradiated ions can be controlled to a suitable value by changing the pressure or the like. The atoms that reach the substrate surface are given energy suitable for thin film growth, migrate on the surface, and can remain in a stable position. As a result, the compound thin film can be expected to have a high bonding force that is chemically stable. Further, since the pressure during film formation is low, contamination such as unnecessary reaction products in CVD does not occur. For example, when the target is Si, an Ar gas is used to form an Si film, an Ar + O ₂ gas is an SiO ₂ film, and an Ar + N ₂ is an Si ₃ N ₄ film. Therefore, the stoichiometry is comparable to the bulk material. Unlike CVD using SiH ₄ gas, a hydrogen-free film can be obtained. Therefore, the stoichiometry is comparable to the bulk material. In addition, it has excellent environmental compatibility without using any dangerous gas.

That is, it is possible to form a film that is closer to the bulk in terms of stoichiometry than that of plasma CVD or general sputtering and has excellent environmental compatibility.
Thus, since ECR plasma provides an ideal thin film growth environment, it is possible to form a thin film that is close to the physical properties of the bulk and is excellent in denseness and smoothness. Regarding the smoothness of the ECR thin film, the unevenness of the film is at the atomic level. For example, when comparing the EFM film and a general RF sputtered film with an AFM (image by atomic force microscope) of Al ₂ O _{3 having} a thickness of 100 nm, the maximum roughness R _max of the ECR film is about 0.48 nm. On the other hand, the maximum roughness of the RF sputtered film is about 5.3 nm.

  Furthermore, since most of the thin film containing the compound does not require any special substrate heating, it can be used for various purposes that dislike high temperature processes. Further, the ECR sputtering method is a beam method, and the coverage can be improved by arranging the substrate in an oblique direction with respect to the ion flow.

Next, an example of the configuration of an ECR sputtering apparatus suitable for forming the lower layer (heat storage layer) will be described with reference to FIG. The entire apparatus is evacuated to a high vacuum by an exhaust pump (not shown) connected to an exhaust port 321. A microwave of 2.45 GHz is introduced into the plasma chamber 314 from the microwave waveguide 413, and Ar is introduced from the first gas inlet 315. At this time, if an ECR (electron cyclotron resonance) condition is established by adjusting the magnetic force of the coil 312 provided around the outer portion of the plasma generation chamber 314, high-density and highly-active plasma is generated in the plasma chamber 314. . The plasmaized gas moves to the sample chamber 317. At this time, when RF (high frequency voltage) of 13.56 MHz is applied to the target 320, sputtering is performed, and O ₂ is introduced from the second gas introduction port 316 provided in the sample chamber 317, thereby being installed in the sample chamber 317. A SiO ₂ film (heat storage layer) is laminated on a substrate (support) 319 placed on the substrate holder 318 formed.

For example, an electrode layer 3 and a heating resistor layer 2 as shown in FIGS. 1A and 1B are formed on the SiO ₂ (heat storage layer) layer 1b of the substrate 1 shown in FIG. The substrate 8 for the liquid jet recording head can be obtained by patterning into a shape to form the heating resistor 2a and further providing the protective layer 4 as necessary.

  The shape of the heating resistor and the configuration of the protective layer 4 are not limited to those illustrated. Next, for example, as shown in FIG. 3, a liquid path 6, a discharge port 7 and, if necessary, a liquid chamber (not shown) are formed on the substrate 8 for the liquid jet recording head. A head can be formed.

  The structure of the liquid jet recording head is not limited to that shown in the figure.

  For example, the example shown in FIG. 3 has a configuration in which the direction in which the liquid is discharged from the discharge port and the direction in which the liquid is supplied to the location where the heat generating portion of the heat energy generator in the liquid path is provided are substantially the same The present invention is not limited to this, and can be applied to, for example, a liquid jet recording head in which the two directions are different from each other (for example, substantially perpendicular).

  The basic structure of the liquid jet recording / recording head in the present invention may be the same as a known one (except that a liquid jet recording head substrate having a layer formed by ECR sputtering is used). Therefore, it can be manufactured without changing the manufacturing process (except for forming the above layer by ECR sputtering).

For example, SiO ₂ is used as the heat storage layer (for example, _{2 to} 2.8 μm), and HfB ₂ is used as the heating resistor (the heating resistance layer) (for example, 0.02 to 0.2 μm). 5 μm) for Ti, Al, Cr, etc., and upper protective layer (first protective layer) (for example 0.5-2 μm) for SiO ₂ , SiN, etc. for the second protective layer (for example 0.3-0. 6 μm) may be Ta, Ta ₂ O ₅ or the like, and the third protective layer may be photosensitive polyimide or the like.

The first to third protective layers referred to here have a three-layered protective layer. The first protective layer is made of an inorganic material that is relatively excellent in electrical insulation, thermal conductivity, and heat resistance, such as an inorganic oxide such as SiO ₂ or an inorganic nitride such as Si ₃ N ₄ . The second protective layer is sticky, has relatively high mechanical strength, and has adhesion and adhesion to the first protective layer, for example, when the first layer is formed of SiO ₂ Is made of a metal material such as Ta. The third protective layer is provided on the main surface of the substrate that may come into contact with the liquid in the liquid flow path including the common liquid chamber portion, and its main role is to prevent liquid permeation and liquid resistance. Furthermore, by providing the electrode wiring part behind the common liquid chamber so as to cover the electrode wiring part, it is possible to prevent the electrode wiring part from being damaged or disconnected during the manufacturing process of the electrode wiring part.

By laminating the layers used for the liquid jet recording head substrate by the ECR sputtering method,
A high-quality layer with a very small deviation from the stoichiometric ratio can be formed even with a thin film, and a film having physical properties very close to those of a bulk material can be formed. Then, the shape and film quality of the wiring step portion are good, and the surface shape can be made gentle. Further, since the film can be formed at a low temperature, the lower wiring is not adversely affected such as generation of hillocks, the flatness of the film is very high, and the range of selection of the manufacturing process is wide. The film (layer) used in a portion close to the liquid (recording liquid) can eliminate almost any dust or the like. Therefore, it is easy to form a layer with few defects and high withstand voltage. As a result, a liquid jet recording head substrate that can withstand long-term use without fear of short-circuiting is obtained, and a highly durable liquid jet recording head capable of stable ejection, high reliability, and high-quality printing is obtained. be able to.

  Further, even when a support such as a polycrystalline body or a metal is used, a heat storage layer (lower layer) having good flatness can be formed.

  In the liquid jet recording head substrate of the present invention, an ECR sputtered layer can be provided for electrical insulation.

  In the substrate for a liquid jet recording head of the present invention, the ECR sputter layer can be disposed between the heating resistor and the pair of electrodes and the support. In the method for producing a substrate for a liquid jet recording head according to the present invention, a layer can be formed by ECR sputtering on the support side from the heating resistor and the pair of electrodes.

  The substrate for a liquid jet recording head according to the present invention may further include a wiring layer between the ECR sputtered layer and the support, separately from the electrodes.

  In the substrate for a liquid jet recording head according to the present invention, the ECR sputtered layer may contain silicon oxide. In the method for manufacturing a substrate for a liquid jet recording head according to the present invention, the layer formed by the ECR sputtering method may contain silicon oxide.

[Example 1]
A substrate for a liquid jet recording head having the layer structure shown in FIG. 6 was prepared, and using this base, a top plate was provided as shown in FIG. 2 to form discharge ports and liquid passages, thereby preparing a liquid jet recording head. .

  As a manufacturing method, a liquid flow path pattern was formed on a substrate by a dry film, and a top plate was bonded onto the substrate using an adhesive. As a material for the top plate, for example, glass can be used. After the substrate and the top plate are bonded together, an inkjet head is produced that cuts perpendicularly to the top plate and the substrate, and uses this cut surface as the face surface to eject ink horizontally to the heating resistor. It becomes possible to do.

First, thermally oxidized SiO ₂ was formed on a silicon substrate (silicon wafer) as a support by introducing oxygen by a bubbling method. The temperature is 1150 ° C. and the time is 12 hours. As shown in FIG. 6, this is referred to as a first heat storage layer 402a.

  On this, a lower wiring 403 which is a first wiring layer is formed. The lower wiring 403 is generally made of aluminum, and is provided, for example, for matrix driving of the heat generating portion.

After the lower wiring was formed on the first heat storage layer, SiO _{2 serving} as the second heat storage layer 402b was formed thereon using the above-described ECR sputtering apparatus. For the ECR sputtering apparatus, AFTEX-7800L (trade name) manufactured by NTT TIF Corporation was used. The film forming conditions are argon 40 sccm, oxygen 7 sccm, film forming pressure 1.51 × 10 ^−0.1 Pa, microwave power 500 W, power applied to the target 500 W, and 26 A applied to the coil forming the magnetic field. did. At this time, the film formation rate is about 100 Å / min, and the formed film thickness is 350 nm. Further, at the time of film formation, as shown in FIG. 4, the film was formed while tilting the substrate by 30 ° with respect to the ion flow and rotating the substrate.

  The second heat storage layer 402 b is formed on the upper surface of the first heat storage layer 402 a on which the lower wiring 403 is formed so as to cover the lower wiring 403.

After the formation of the second heat storage layer, the cross-sectional shapes of the lower layer wiring 403 and the second heat storage layer 402b (particularly, the stepped portion due to the lower wiring) were observed, as shown in FIG. 7 (a) and FIG. 7 (b). The shape was not like that shown in FIG. FIG. 9 shows a state in which the SiO ₂ layer 410 is formed on the aluminum wiring 409 by the bias sputtering method. When the film was formed by the ECR sputtering film forming method, the generation of particles was very small as compared with the case of using the bias sputtering method, which was a practically very preferable level.

In addition, after the second heat storage layer (SiO ₂ ) is formed by ECR sputtering, the surface level difference of the portion where the wiring is not formed is measured using a stylus type roughness meter. It was as follows, and a significant difference from that before film formation was not recognized.

  Experimentally, a thermolabel was attached to the substrate surface, and the substrate temperature during ECR sputtering film formation was measured, and it was confirmed that the temperature was 150 ° C. or lower. Also, no hillock phenomenon was observed in the lower wiring 403 made of aluminum.

Next, a heating resistance layer (20 μm × 100 μm, film thickness 0.16 μm, wiring density 16 Pel) made of HfB ₂ by general sputtering is formed on the second heat storage layer, and an electrode layer made of Al by electron beam evaporation ( A film thickness of 0.6 μm and a width of 20 μm) was formed.

After that, a pattern was formed with a resist, and then wet etching was performed using this as a mask to form the heating resistance layer 404 and the electrode layer 405 with the same pattern as the pattern shown in FIG. A mixed solution of phosphoric acid: nitric acid: acetic acid: water = 16: 1: 2: 1 was used for wet etching of Al, and a mixed solution of hydrofluoric acid and nitric acid was used for etching of HfB ₂ . Thereafter, the resist was peeled off, and a pattern of Al and HfB ₂ was completed. That is, the electrodes 3a and 3b are connected to the respective heating resistors 2a apart from each other. At this time, 256 heating resistors were provided side by side. The damage of the second heat storage layer 402b due to ECR sputtering formed in the lower layer of the HfB ₂ film was extremely small.

Next, a protective layer 406 (thickness 2 μm) made of SiO ₂ and an anti-cavitation layer 407 (0.5 μm) made of Ta are both formed on the upper part of the portion where the electrode and the heating resistor are formed by a general sputtering method. Thus, a substrate for a liquid jet recording head was obtained.

  A liquid path 6 and a liquid chamber (not shown) as shown in FIG. 3 are formed on the above-described substrate for a liquid jet recording head by a dry film, a top plate is bonded with an adhesive, and finally a slicer is cut. Thus, the surface forming the discharge port surface was cut to obtain a liquid jet recording head.

  A discharge durability test was performed on 1000 liquid jet recording heads thus prepared.

A printing signal of 1.1 Vth and a pulse width of 10 μs is applied to each heating resistor to discharge liquid from each discharge port, and the number of cycles of the electrical signal until the heating resistor is disconnected is measured and its durability is evaluated. did. The head has 256 heat generating resistors per head, and when one of the heat generating resistors is disconnected, the head is cut off for testing. The results obtained are as shown in Table 1. In other words, in 99.8% of the 1000 heads, liquid ejection of 10 ⁹ times or more was successfully performed.

[Comparative Example 1]
1000 liquid jet recording heads were prepared in the same manner as in Example 1 except that the second heat storage layer (SiO ₂ , film thickness: 350 nm) was formed by plasma CVD instead of ECR sputtering, and discharge durability was achieved. The test was conducted.

The film formation temperature of plasma CVD is 200 ° C., the pressure at the time of film formation is 2.0 torr (270 Pa), and the gas is SiH ₄ : N ₂ O = 200 sccm: 6000 sccm.

  After the formation of the second heat storage layer, the cross-sectional shapes of the lower layer wiring 403 and the second heat storage layer 402b were observed, and the shape was as shown in FIG.

When over-etching was performed during HfB ₂ (heating resistance layer) etching and the cross-sectional shape was measured, the film corresponding to the portion B in FIG. 7A was etched due to low density.

  The results obtained by the discharge durability test are as follows.

When the cause was investigated by disassembling the broken head with a pulse number of 1 × 10 ⁷ or less, a crack was generated in the portion corresponding to the portion B shown in FIG. Ink penetrated from the cavitation layer, and the lower wiring 403 was corroded.

[Example 2]
A liquid jet recording head was prepared and evaluated in the same manner as in Example 1 except that the etching of HfB ₂ (heating resistance layer) was dry etching using a chlorine-based gas. There was little damage on the second heat storage layer. When an endurance test was performed, the same result as in Example 1 was obtained.

[Comparative Example 2]
A liquid jet recording head was prepared and evaluated in the same manner as in Comparative Example 1 except that chlorine-based gas was used and HfB ₂ (heating resistance layer) was etched by dry etching. Again, damage was caused at the site corresponding to part B in FIG. 7 (a), and no improvement was observed in the results of the durability test.

[Comparative Example 3]
A liquid jet recording head was prepared and evaluated in the same manner as in Comparative Example 1 except that the substrate temperature during plasma CVD film formation was raised to 300 ° C. in order to improve the film quality of the stepped portion.

However, hillocks as shown in FIG. 8 have occurred at the edge of the aluminum wiring located under the plasma CVD-SiO ₂ . When the durability test was conducted, the results deteriorated. When the broken head was disassembled and examined, hillocks occurred, so that the coating coverage as a film deteriorated in the portion where the substantial film thickness step in the SiO ₂ film above it increased, and cracks occurred in the step part. From this crack, it was found that the ink contacted the electrode and electrocorrosion occurred.

  The liquid jet recording head of the present invention can be used in an ink jet printer or the like.

(A) is a schematic plan view of an example of a substrate for a liquid jet recording head, and (b) is a schematic cross-sectional view taken along line X-X ′. It is a cross-sectional schematic diagram which shows the structural example of the support body used for formation of a base | substrate. FIG. 4 is a schematic vertical sectional view of a plane including a liquid path, as an example of a liquid jet recording head. It is a schematic diagram which shows the structural example of the ECR sputtering apparatus which inclined and arrange | positioned the board | substrate. It is a schematic diagram which shows the basic structural example of an ECR sputtering apparatus. 3 is a schematic cross-sectional view of an example of a substrate for a liquid jet recording head. FIG. (A) is a schematic diagram showing the cross-sectional shape of the SiO ₂ layer when there is a step in the aluminum wiring, (b) is a schematic diagram showing the cross-sectional shape when a thin film is further laminated on the SiO ₂ layer, (c) Is a schematic diagram showing the planar shape. It is a schematic view showing a cross-sectional shape of the SiO ₂ layer in the case where there is a hillock of an aluminum wiring. It is a schematic view showing a cross-sectional shape of the SiO ₂ layer in the case where there is a step of the aluminum wiring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 1b Heat storage layer 2 Heat generating resistive layer 2a Heat generating resistive element 3 Electrode layer 3a, 3b Electrode 4 Protective layer 5 Top plate 6 Liquid flow path 7 Discharge port 8 Liquid jet recording head substrate 312 Coil 314 Plasma chamber 315 First Gas inlet 316 Second gas inlet 317 Sample chamber 318, 323 Substrate holder 319, 322 Substrate 320 Target 321 Exhaust port 413 Microwave waveguide 401 Silicon substrate 402 Thermal storage layer 402a First thermal storage layer 402b Second thermal storage layer 403 Lower wiring 404 Heating resistance layer 405 Electrode layer 406 Protective layer 407 Anti-cavitation layer 409 Aluminum wiring 410 SiO ₂ thin film 411 Thin film

Claims (9)

A substrate used in a liquid jet recording head that discharges liquid droplets from a discharge port,
A support, a heat storage layer formed on the support, a heating resistor for generating thermal energy, and a pair of electrodes formed on the support so as to be electrically connected to the heating resistor;
A protective layer covering the pair of electrodes and the heating resistor,
A substrate for a liquid jet recording head, wherein the heat storage layer is an ECR sputter layer.   The heat storage layer is formed by laminating a plurality of matrix wiring layers formed on a support via an insulating film, and the insulating layer formed on the wiring layer is an ECR sputtered layer. A substrate for a liquid jet recording head.   The liquid jet recording head substrate according to claim 1, wherein the ECR sputtered layer contains silicon oxide.   The liquid jet recording head substrate according to claim 1, wherein the ECR sputtered layer contains silicon nitride oxide. A support, a heat storage layer formed on the support, a heating resistor for generating thermal energy, and a pair of electrodes formed on the support so as to be electrically connected to the heating resistor;
In a method for manufacturing a substrate for a liquid jet recording head comprising the pair of electrodes and a protective layer covering the heating resistor,
A method of manufacturing a substrate for a liquid jet recording head, wherein the heat storage layer is formed by an ECR sputtering method.   6. The heat storage layer is formed by laminating a plurality of matrix wiring layers formed on a support via an insulating film, and the insulating layer formed on the wiring layer is an ECR sputtered layer. Manufacturing method for a liquid jet recording head.   The method for manufacturing a substrate for a liquid jet recording head according to claim 5, wherein the ECR sputter layer contains silicon oxide.   The method for manufacturing a substrate for a liquid jet recording head according to claim 5, wherein the ECR sputter layer contains silicon nitride oxide. The substrate for a liquid jet recording head according to claim 1;
A liquid path for flowing a recording liquid provided corresponding to a heating resistor provided in the liquid jet recording head substrate; and
A liquid jet recording head having an ejection port which communicates with the liquid path and ejects a recording liquid.

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