JP2002011886A - Substrate for inkjet recording head, inkjet recording head, and method for producing substrate for head - Google Patents

Abstract

(57) [Problem] To improve the step coverage of an upper protective film for protecting a heating resistor layer and a pair of electrodes formed on the heat generating resistive layer, and to reduce the thickness of the protective film. SOLUTION: In the substrate for an ink jet recording head, an edge portion of the electrode 4 on the side of the heat acting portion 8 has a vertical surface 4a substantially perpendicular to the surface of the heating resistor layer 3, and an inclined surface continuous from the vertical surface 4a to the electrode upper surface 4c. The portion 4b is formed. Then, a protective layer 5 is formed on the heating resistance layer 3 and the electrode 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for an ink jet recording head and a method for producing the same, a recording head using the substrate, and a recording apparatus having the recording head, and more particularly to a device using a thermal energy generating means as an ink jet source. .

[0002]

2. Description of the Related Art Among various recording methods known at present, it is a non-impact recording method in which almost no noise is generated at the time of recording, high-speed recording is possible, and a special fixing process is performed on plain paper. The so-called inkjet recording method (Inkjet recording method) that enables recording without the need
Is an extremely useful recording method. Regarding the ink jet recording method, various methods have been proposed so far, some of which have been commercialized with improvements, and some of which are still being put to practical use.

In the ink-jet recording method, recording is performed by causing droplets of a recording liquid called ink to fly according to various operating principles and attaching the droplets to a recording material such as paper.

[0004] The present applicant has already proposed a method relating to the ink jet recording method. This method has been proposed in JP-A-52-118798, the basic principle of which is as outlined below. In other words, this ink jet recording method gives a thermal pulse as an information signal to the recording liquid introduced into the working chamber capable of containing the recording liquid, whereby the recording liquid generates a vapor bubble and self-shrinks. In this method, the recording liquid is ejected from a liquid ejection port communicating with the action chamber in accordance with the acting force generated in the process, and is ejected as small droplets, and the droplet is attached to a recording material to perform recording.

In this method, a high-density multi-array structure is easily adapted to high-speed printing and color printing, and the structure of the apparatus is simpler than that of the conventional apparatus. It has the advantages of being able to be designed and mass-produced, and being able to easily make it longer by making full use of the advantages of IC technology and micro-machining technology, which have made remarkable advances in technology and reliability in the semiconductor field. Is a flexible way.

A characteristic recording head of an ink jet recording apparatus used in the above ink jet recording method is provided with a thermal energy generating means for discharging a recording liquid from a liquid discharge port to form flying droplets.

[0007] The thermal energy generating means is used to efficiently apply the generated thermal energy to the recording liquid, and to increase the ON-OFF response speed of the thermal action to the recording liquid.
It is said that it is desirable to provide the recording liquid in direct contact with it.

However, since the above-mentioned heat energy generating means is basically composed of a heat generating resistance layer which generates heat when energized and a pair of electrodes for energizing the heat generating resistance layer, the heat energy generating means has a heat generating resistance. When the layer is in direct contact with the recording liquid, electricity flows through the recording liquid depending on the electric resistance value of the recording liquid, the recording liquid itself is electrolyzed by the flow of electricity through the recording liquid, or generates heat. When the heating layer is energized, the heating resistor layer and the recording liquid react with each other, and the resistance value may change due to corrosion of the heating resistor layer, or the heating resistor layer may be damaged or broken.

For this purpose, conventionally, the heat generating resistance layer is made of an inorganic material having relatively excellent properties as a heat generating resistance material such as an alloy such as NiCr or a metal boride such as ZrB ₂ and HfB ₂ , By providing a protective layer made of a material having excellent oxidation resistance such as SiO ₂ on the heating resistor layer made of the material, the heating resistor layer is prevented from directly contacting the recording liquid,
It has been proposed to solve the above-mentioned problems and improve reliability and durability in repeated use.

In forming such thermal energy generating means for an ink jet recording head,
8 (a plan view of the head base) and FIG. 9 (X-
As shown in the cross-sectional view taken along the line X ′), after the heat generating resistance layer 3 is formed on the desired substrate 1 via the heat storage layer 2, the electrode 4 and the protective layer 5 are sequentially laminated on the heat generating resistance layer 3. In general, the protective layer of such a thermal energy generating means is required to sufficiently perform various functions as a protective layer such as prevention of breakage of the heating resistance layer or short circuit between electrodes as described above. , And uniformly cover the required portions of the heating resistance layer and the electrode without having a layer defect such as a pinhole (cover).
Is required.

In addition, in such an ink jet recording head, as described above, since electrodes are generally formed on the heating resistor layer, a step (step) occurs between the electrode and the heating resistor layer. Since the portion tends to have a non-uniform layer thickness, the layer must be formed so as to sufficiently cover the step (step coverage) so as not to produce an exposed portion. That is, in a state where the step coverage is insufficient (the portion indicated by reference numeral 10 in FIG. 9), the exposed portion of the heat-generating resistive layer comes into direct contact with the recording liquid, so that the recording liquid is electrolyzed, or In some cases, the heat-generating resistance layer reacts to destroy the heat-generating resistance layer. In addition, unevenness of the film quality and the like easily occur in such a step portion, and such unevenness of the film quality causes partial concentration of thermal stress generated in the protective layer due to repetition of heat generation, and cracks ( Cracks)
In some cases, the recording liquid penetrated from the cracks, resulting in the destruction of the heating resistance layer as described above. Furthermore, the recording liquid may enter through the pinhole and break the heat generating resistance layer.

In particular, with regard to step coverage, if the pinholes are more important and step coverage is poor, most heaters are destroyed and reliability is significantly reduced.

Conventionally, in order to solve such a problem, it is generally practiced to increase the thickness of the protective layer to improve step coverage and reduce pinholes.

However, increasing the thickness of the protective layer is
Although it contributes to the reduction of step coverage and pinholes, the thicker protective layer hinders the supply of heat to the recording liquid, and causes the following new problems.

That is, the heat generated in the heat generating resistive layer is transmitted to the recording liquid through the protective layer, and the thermal resistance between the heat generating resistive layer and the surface of the protective layer, which is the surface where the heat acts, is considered. Is increased by increasing the thickness of the protective layer, so that it becomes necessary to apply an excessive power load to the heating resistance layer. 1. Power saving is disadvantageous. 2. Unnecessary heat accumulates in the substrate, resulting in poor thermal response. This causes a problem that the durability of the heat-generating resistive layer deteriorates due to excessive power.

Such a problem can be overcome by making the protective layer thinner. However, in the conventional method of forming an ink jet recording head using a film forming method such as sputtering or vapor deposition for forming the layer, a step coverage defect occurs. Because of the above, there is a disadvantage in durability as described above,
It was difficult to make the protective layer thin.

It is also known that during recording with the above-described ink jet recording head, the foaming stability of the recording liquid generally improves as the recording liquid is rapidly heated. That is, an electric signal applied to the thermal energy generating means, generally a rectangular electric pulse, the shorter the pulse width is, the better the foaming stability of the recording liquid is, and thus, the ejection stability of the flying droplet is improved. Is improved, and the recording quality is improved. However, in the conventional ink jet recording head, as described above, the thickness of the protective layer must be increased, so that the thermal resistance of the protective layer becomes large, and it is necessary to generate unnecessary heat by the thermal energy generating means. Because of this, the durability and the thermal responsiveness are degraded, which makes it difficult to shorten the pulse width, and the improvement of the recording quality is naturally limited.

Therefore, in order to solve the above-mentioned problems, as described in JP-A-04-320847, in the etching step of the electrode layer, the etching is performed while the resist is receded, so that the etching cross-sectional shape is tapered. Improvements in the step coverage of the upper protective layer have been proposed.

In Japanese Patent Application Laid-Open No. 04-320848, in the electrode layer etching step, the resist is etched to retreat the pattern and then the etching is repeated halfway, so that the cross-sectional shape is stepped. It has been proposed to improve the step coverage of the upper protective layer by reducing the steps of each step.

[0020]

Problems to be Solved by the Invention Japanese Patent Laid-Open No. 04-3208
In the method described in Japanese Patent Publication No. 47, etching is performed while the resist is receded, but there are the following problems. 1. It was necessary to pay attention to the resist material and baking conditions in order to perform etching while the resist was receded. When the material of the resist changes, the retreat speed changes, and a desired taper angle may not be obtained. Further, when the baking conditions are changed, the resist retreating speed is changed, and a desired taper angle may not be obtained. 2. In order to etch while retreating the resist, it is necessary to strictly control the temperature of the solution of trimethyl hydroxide. When the temperature changes, the ratio of the etching rate of the resist to the etching rate of the electrode material changes, so the desired taper Sometimes corners could not be obtained.

In particular, when the upper protective layer is thinner than the electrode layer, more strict control of the taper angle is required.

In the method described in Japanese Patent Application Laid-Open No. 04-320848, the resist is etched by using a trimethyl hydroxide solution. However, since the etching rate of the resist changes depending on the resist material, the resist material is limited. Therefore, strict control is required because the etching rate of the resist varies depending on the baking conditions of the resist, and strict control etching of the solution temperature of the trimethyl hydroxide solution of the etching solution is required. Further, since the trimethyl hydroxide solution may etch the electrode, the electrode surface may be etched when the resist is etched, and the desired shape may not be obtained.

Accordingly, an object of the present invention is to improve the step coverage of an upper protective film for protecting a heating resistor layer and a pair of electrodes formed thereon, and to reduce the thickness of the protective film. Another object of the present invention is to provide an ink jet recording head using a substrate produced by the method, a method of producing the same, and a recording apparatus having the recording head.

[0024]

In order to achieve the above object, a head substrate according to the present invention comprises a heating resistor layer, at least one pair of electrodes formed separately on the heating resistor layer, and the heating resistor. In a substrate for an inkjet recording head having a layer and a protective film covering the electrode, an edge of the electrode is substantially perpendicular to the surface of the heating resistance layer,
It is characterized by being formed with an inclined portion that is continuous from the vertical surface to the upper surface of the electrode.

Further, the ink jet recording head of the present invention has a liquid discharge port for discharging a recording liquid, a thermal energy generating means for supplying a discharging energy to the recording liquid, and a protective layer covering the thermal energy generating means. And
In the ink jet recording head, wherein the heat energy generating means includes a heating resistor layer and at least a pair of electrodes formed separately on the heating resistor layer, an edge portion of the electrode is formed on a surface of the heating resistor layer. It is characterized by being formed of a surface substantially perpendicular to the surface and an inclined portion continuous from the vertical surface to the upper surface of the electrode.

According to the present invention, there is also provided a method of manufacturing a substrate for an ink jet recording head, comprising the steps of sequentially laminating the heating resistance layer and the conductor layer on the substrate, and patterning the heating resistance layer and the conductor layer. And a step of patterning only the conductor layer on the heating resistance layer to form the electrode, and a step of sputter etching the electrode,
Forming an insulating protective layer so as to cover the electrode and the heating resistor layer.

In this case, it is preferable that the gas of the sputter etch contains argon as a main component.

According to the present invention, there is also provided a method of manufacturing a substrate for an ink jet recording head as described above, wherein a step of sequentially laminating the heating resistance layer and the conductor layer on the substrate and a step of patterning the heating resistance layer and the conductor layer Patterning only the conductor layer on the heating resistance layer to form the electrode; and forming an insulating protective layer so as to cover the electrode and the heating resistance layer. In the step of patterning only the conductor layer on the layer, a resist pattern is formed on the conductor layer, the conductor layer is partially etched by dry etching while the resist is receded, and the electrode is formed by performing wet etching. Is formed.

In the step of patterning only the conductor layer on the heat-generating resistance layer, it is more preferable that the dry etching is performed partway and then the wet etching is performed after the treatment with a polymer removing solution.

(Operation) In the invention as described above, the edge of the electrode formed on the heating resistor layer has a vertical surface substantially perpendicular to the surface of the heating resistor layer, and a slope continuous from this vertical surface to the upper surface of the electrode. And a part. That is, since the corner portion of the step formed by the heating resistor layer and the electrode is cut off, the step coverage of the protective layer is improved. In addition, the length of the vertical surface of the electrode with respect to the surface of the heating resistor layer can be reduced, so that the protective layer can be made thinner.

However, since the change in the distance between the electrodes is smaller than that in the case where the edge portion is formed only by the inclined portion, the heating resistance value between the electrodes is stabilized. In addition, only the slanted portion creates a very thin portion on the electrode,
In the shape as described above, a certain thickness or more is secured, and the durability is improved.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings as necessary.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
(A) is a plan view of the vicinity of a thermal energy generating means of the head, and (B) is a plan view of X-ray in (A). FIG. 3 shows a cross-sectional view taken along line X ′.

In the substrate for an ink jet recording head shown in FIG. 1, the edge of the electrode 4 on the side of the heat acting portion 8 has a vertical surface 4 a substantially perpendicular to the surface of the heat generating resistance layer (electrothermal converter) 3. And an inclined portion 4b continuous from the vertical surface 4a to the electrode upper surface 4c. Reference numeral 8 denotes a heat acting portion that supplies power to the heat generating portion of the heat generating resistance layer 3 formed between the electrodes 4 and transmits the generated heat to the recording liquid.

According to this configuration, the heating resistance layer 3 and the electrode 4
Because the corner of the step due to is shaved off,
The step coverage of the protective layer 5 is improved. In addition, the length of the vertical surface of the electrode 4 with respect to the surface of the heating resistance layer 3 can be reduced, so that the thickness of the protective layer 5 can be reduced.

However, the change in the distance between the electrodes is smaller than that in the case where the edge portion is formed of only the inclined portion, so that the heating resistance between the electrodes 4 is stabilized. Moreover, a very thin portion is formed on the electrode 4 only with the inclined portion, but a certain thickness or more is secured in the above shape,
The durability is improved.

In order to manufacture a recording head substrate having such a shape, a heating resistor layer and a conductor layer are formed in this order on a substrate of a desired material (generally, various shapes) such as glass, ceramics or plastic. Film. next,
After applying a resist and patterning the resist using a photolithography (hereinafter, referred to as photolithography) technique, the heating resistance layer and the conductor layer corresponding to the portion where the resist is missing are etched into a desired pattern.

Further, a new resist is applied, the resist is patterned by using the photolithography technique, and only the conductor layer corresponding to the portion where the resist is missing is etched to expose the heating resistor layer. Since only the conductor layer is etched,
It is important that the etching has a selectivity with respect to the heating resistance layer. It is also important to select an etching method that does not damage the heating resistor layer. Therefore, a wet etching method is generally employed. Here, in order to optimize the shape of the step formed by the edge of the electrode formed by etching the conductor layer and the surface of the heating resistor layer and to optimize the step coverage of the upper protective layer, the upper corner of the electrode must be formed. It is important that it has a tapered shape. This is because, when the upper protective layer is formed when the upper part of the electrode remains at the corner, a film is deposited around the corner, and the quality of the protective layer covering the lower part of the negative electrode deteriorates or cracks occur. Or occur.

Therefore, after the conductor layer is wet-etched, the resist is peeled off, and the upper corner portion of the electrode can be tapered by sputter-etching the electrode pattern. If a sputter etch containing argon as a main component is used, only the corners of the pattern can be etched because of the physical etching, and as a result, only the upper corners of the electrodes can be etched without damaging the heating resistance layer.

The amount of etching to be sputter-etched may be any amount as long as the upper corner of the electrode is slightly tapered.
It can be set according to the etching conditions.

As described above, at least one set of thermal energy generating means including at least one pair of electrodes for applying a voltage pulse (electric signal) to the heating resistor is completed. Then, an upper layer serving as a protective layer is formed on the thermal energy generating means.

Hereinafter, an example of a method of forming a head base according to the present embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view of FIG.
The process drawing seen in the X 'line section is shown.

First, as shown in FIG. 2A, an insulator (such as an oxide) is formed as a heat storage layer 2 on a desired substrate 1 by a thermal oxidation method or a CVD method. Then, the heat generating resistance layer 3 is formed on the heat storage layer 2 by using a vacuum evaporation method or a sputtering method. Next, the electrode 4 is formed on the heating resistance layer 3.
Is formed on the heating resistor layer 3 by using a vacuum evaporation method, a sputtering method, or the like. Then, although not shown, after applying the resist, the resist is patterned by using a well-known photolithography technique, and the conductor layer and the heat generating resistive layer corresponding to the resist missing portion are etched.

Next, after the resist is peeled off and a new resist is applied, a resist corresponding to the heat acting portion 8 is formed by using a photolithographic technique in order to obtain the heat acting portion 8 as shown in FIG. After opening the portion, the conductor layer 4 'is wet-etched to obtain the electrode 4 having a desired pattern.

Next, after the resist is stripped, as shown in FIG. 2C, a sputter etch (also referred to as reverse sputtering) is performed so that only the upper corner portion of the edge of the electrode 4 on the side of the heat acting portion 8 is formed. To make the corners tapered. In other words, the fact that the etching rate at the corners is higher than that of the other parts during sputter etching is used.

Finally, as shown in FIG. 2D, for example, Si ₃ N ₄ , S ₃
A protective layer 5 made of a desired material such as iO ₂ , SiON, Ta ₂ O ₅
It is formed by vacuum evaporation, sputtering, CVD, or the like.

The protective layer 5 does not need to be made of a single material. For example, the cavitation resistance (the contact resistance of the protective layer 5 caused by bubbles generated by driving the thermal energy generating means) is improved. For the purpose of, for example, a plurality of configurations made of two or more types of materials may be used.

Thus, the head substrate shown in FIG. 1B is produced.

FIG. 4 is a diagram showing a completed state of an example of an ink jet recording head obtained by applying the head substrate of the present invention. Reference numeral 21 denotes a liquid discharge port for discharging a recording liquid.

In the ink jet recording head shown in this figure, after the thermal energy generating means having the above-mentioned protective layer is formed on the substrate 1, the working chamber corresponding to each of the thermal energy generating means and the working chambers are provided. This is obtained by joining a top plate 16 having a groove formed for providing a communicating liquid discharge port 21 as shown in FIG. In FIG. 3, a portion indicated by reference numeral 17 is a groove for forming a liquid flow path where an action chamber is provided, and a portion indicated by reference numeral 19 is a common groove for supplying a recording liquid to the liquid flow path 17. A groove that becomes a liquid chamber.

A liquid supply pipe 20 as shown in FIG. 4 is connected to the common liquid chamber 19 as necessary, and a recording liquid is introduced from outside the head through the liquid supply pipe 20. Also, top plate 1
When joining 6, it is desirable that sufficient alignment be performed so that each of the thermal energy generating means corresponds to each of the liquid flow paths 17.

Although not particularly described above, the formation of the liquid discharge ports and the liquid flow paths is not necessarily performed by using the grooved plate as shown in FIG. Or the like. Further, the present invention is not limited to a multi-array type ink jet recording head having a plurality of liquid discharge ports as described above, and is of course applicable to a single array type ink jet recording head having one liquid discharge port. You can do it.

In producing such an ink jet recording head, in the head base as illustrated in FIG. 9, layer defects such as pinholes are liable to occur in the protective layer 5 as described above. In order to easily form a portion, the thickness of the protective layer must be increased more than necessary (normally, 1.5 times or more of the electrode thickness). However, in the present embodiment, the conductor layer is wet-etched to form an electrode, the resist is peeled off, and then the electrode pattern is sputter-etched to form a tapered upper corner portion of the electrode edge portion. Layer defects such as non-uniform film quality which cause pinholes and cracks can be eliminated.

Further, by optimizing the shape of the step between the electrode edge portion and the surface of the heating resistor layer, the problem associated with increasing the thickness of the protective layer 5 for the purpose of improving the step coverage is eliminated, and power saving is achieved. Needless to say, an inkjet recording head having high durability and high-speed thermal responsiveness can be provided. By the way, in the present embodiment, the thickness of the protective layer was not more than 1 time of the electrode thickness.

Further, since the shape of the electrode edge portion can be strictly controlled by being strictly etched by sputter etching, a protective layer having a good step coverage can be formed on the electrode even with a protective layer thinner than the electrode.

Further, in the present embodiment, the above-mentioned heat generating resistance layer, electrode and upper layer are formed by using well-known materials, respectively.
For example, it is formed using a known film forming method such as a sputtering method such as high frequency (RF) sputtering, a chemical vapor deposition (CVD) method, and a vacuum evaporation method without any particular limitation.

In addition, any method can be used for the sputter etching of the electrode as long as the sputter etching conditions can be set, and the RIE method is often used.

Further, since the etching gas species is used for physical etching, an inert gas is required, and an argon gas is generally used.

(Second Embodiment) As in the above-described embodiment, to produce the substrate for an ink jet recording head shown in FIG. 1, first, a substrate made of a desired material such as glass, ceramics, or plastic is used. Then, a heating resistance layer and a conductor layer are formed. Next, the resist is patterned using the photolithography technique, and the heat generating resistance layer and the conductor layer are etched to form a desired pattern. Next, an electrode is formed by patterning the resist using the photolithography technique and etching only the conductor layer. After that, an upper protective layer is formed.In order to optimize the shape of the step between the electrode edge portion and the heating resistor layer and to optimize the step coverage of the upper protective layer, the upper corner portion of the electrode edge portion is tapered. As mentioned above, it is important that

In the present embodiment, in order to taper the upper corner portion of the electrode edge portion, first, the conductive layer is etched so as to have a tapered cross section while the resist is receded by dry etching. Next, without stripping the resist, wet etching was performed on the conductor layer partially etched to form an electrode. By doing so, it is possible to etch only the electrode layer without damaging the heating resistance layer while keeping the upper corner of the electrode tapered. The reason why the electrodes were finally formed by wet etching is the same as in the first embodiment.

The amount of etching for dry etching is sufficient if the taper is sufficient and the heating resistance layer is not exposed to dry etching. Preferably, the etching amount is at least half the thickness of the conductor layer serving as an electrode and the remaining electrode layer is at least 500 mm. What is necessary is just to set so that it may etch.

Further, if wet etching is performed as it is after dry etching, an etching hole having a sectional shape as shown in FIG. When the upper protective layer is formed, the shape becomes as shown in FIG. 6B, and a portion where step coverage is deteriorated, that is, a portion 14 of the protective layer having poor film quality is generated.

The reason for such a shape is that a polymer resulting from the dry etching gas is formed on the exposed portion of the electrode during the dry etching, and thereafter the etching of the portion does not progress in the wet etching. This results in an etched hole having a cross-sectional shape as indicated by reference numeral 13.

For this reason, after the dry etching, the polymer is removed with a polymer removing agent containing dimethyl sulfoxide as a main component, and then wet-etched, so that an etching hole having a sectional shape as shown in FIG. An etching hole having a sectional shape as shown in FIG. 5D is obtained.

As described above, at least one set of thermal energy generating means including at least one pair of electrodes for applying a voltage pulse to the heating resistor is completed. Then, an upper layer serving as a protective layer is formed on the thermal energy generating means.

Hereinafter, an example of a method of forming a head base according to the present embodiment will be described with reference to FIG. FIG. 5 is a cross-sectional view of FIG.
The process drawing seen in the X 'line section is shown.

First, as shown in FIG. 5A, an insulator (such as an oxide) is formed as a heat storage layer 2 on a desired substrate 1 by a thermal oxidation method or a CVD method. Then, the heat generating resistance layer 3 is formed on the heat storage layer 2 by using a vacuum evaporation method or a sputtering method. Next, the electrode 4 is formed on the heating resistance layer 3.
Is formed on the heating resistor layer 3 by using a vacuum evaporation method, a sputtering method, or the like. Then, although not shown, after applying the resist, the resist is patterned by using a well-known photolithography technique, and the conductor layer and the heat generating resistive layer corresponding to the resist missing portion are etched.

Next, in order to remove the resist and obtain a thermal energy generating means, a resist 6 having a desired pattern is newly formed on the conductor layer 4 'as shown in FIG. 5B.

Next, as shown in FIG. 5C, the conductive layer 4 'is etched partway while the resist 6 is receded by dry etching, so that the side surfaces of the etching holes are tapered.

Next, a immersion treatment is carried out with a polymer removing liquid containing dimethyl sulfoxide as a main component to remove the polymer (not shown) attached to the etching hole.

Next, as shown in FIG. 5D, the remaining conductor layer is wet-etched to expose the heating resistor layer 3 and to form the electrode 4. Then, the resist 6 is removed.

Finally, as shown in FIG. 5D, at least one pair of spaced-apart electrodes 4 is formed on the heat-generating resistance layer 3 and one or more thermal energy generating means is provided with, for example, Si ₃ N
₄ , a protective layer 5 made of a desired material such as SiO ₂ , SiON, Ta ₂ O ₅ or the like.
Is formed using vacuum evaporation, sputtering, CVD, or the like.

As in the first embodiment, the protective layer 5 does not need to be made of a single material. For example, for the purpose of improving cavitation resistance, the protective layer 5 may have a plurality of structures made of two or more materials. Good thing.

Further, an ink jet recording head is prepared by using the head substrate having the above-mentioned energy generating means. For this recording head, for example, the one described in the first embodiment can be applied (see FIGS. 3 and 4). In producing such a recording head, the head base as illustrated in FIG. As described above, since layer defects such as pinholes are likely to occur in the protective layer 5, and particularly in step 10, an exposed portion is likely to occur. Above) had to do. However, in this embodiment, in order to form an electrode, the conductor layer is first etched so that the cross section becomes tapered halfway while the resist is receded by dry etching, and then the wet etching is performed without removing the resist. Thus, since the electrodes are formed, it is possible to eliminate the above-mentioned layer defects such as non-uniformity of the film quality which cause the generation of pinholes and cracks in the protective layer.

Further, in some cases, after the dry etching, the polymer is removed with a polymer remover containing dimethyl sulfoxide as a main component, thereby eliminating poor etching due to the adhesion of the polymer and preventing the formation of a portion of the protective layer having poor quality. Can be prevented.

Further, according to the method of the present embodiment, the head substrate shown in FIG. 1B is formed, but in such a shape, the corner of the step formed by the heating resistor layer 3 and the electrode 4 is cut off. The step coverage of the protective layer 5 is improved because of the bent shape. In addition, the length of the vertical surface of the electrode 4 with respect to the surface of the heating resistance layer 3 can be reduced, so that the thickness of the protective layer 5 can be reduced. However, the change in the distance between the electrodes is smaller than that in the case where the edge portion is formed only by the inclined portion, so that the heating resistance value between the electrodes 4 is stabilized. Moreover, a very thin portion is formed on the electrode 4 only by the inclined portion, but the shape as described above secures a certain thickness or more, and the durability is improved.

That is, by optimizing the shape of the step between the electrode edge portion and the surface of the heating resistor layer, the problem associated with increasing the thickness of the protective layer 5 for the purpose of improving the step coverage is eliminated, and power saving is achieved. Needless to say, an inkjet recording head having high durability and high-speed thermal responsiveness can be provided. By the way, in the present embodiment, the thickness of the protective layer was not more than 1 time of the electrode thickness.

Further, since the etching can be strictly performed by dry etching, a protective layer having good step coverage can be formed on the electrode even if the protective layer is thinner than the electrode.

Further, in the present embodiment, the above-mentioned heating resistance layer, electrode and upper layer are each made of a known material,
For example, it is formed using a known film forming method such as a sputtering method such as high frequency (RF) sputtering, a chemical vapor deposition (CVD) method, and a vacuum evaporation method without any particular limitation.

In addition, any method may be used as long as the etching conditions for forming a tapered shape can be set for the dry etching of the electrode, and the ECR method or the RIE method is often used.

The etching solution for the wet etching of the electrode may be a general etching solution, for example, a mixture of nitric acid, phosphoric acid and acetic acid is often used.

The polymer removing agent is generally a polymer removing agent containing dimethyl sulfoxide as a main component, but other polymer removing agents may be used.

[0083]

Next, the above embodiment will be described in more detail.

Example 1 The first embodiment will be described with reference to materials and numerical values.

In this example, the liquid jet recording head shown in FIG. 4 was prepared as follows.

Referring to FIG. 2, first, a thermal oxidation thermal storage layer 2 made of SiO ₂ having a thickness of 5 μm was formed on a substrate 1 made of Si. Then, a heating resistance layer 3 made of HfB ₂ was formed to a thickness of 1300 ° by a sputtering method. Next, on the heating resistance layer 3, an Al conductor layer 4 'serving as the electrode 4 is formed.
Was formed to a thickness of 6000 ° by sputtering (FIG. 2).
(A)). Then, the resist is patterned by using a well-known photolithography (photolithography) technique, and the conductor layer 4 ′ and the heating resistor layer 3 are etched.

Next, in order to obtain thermal energy generating means, a desired resist pattern is formed on the conductor layer 4 'and etched to obtain an electrode 4 (see FIG. 2B).

Next, as shown in FIG. 2 (c), by performing a sputter etch using an argon gas using an RIE apparatus, only the corner at the upper edge of the electrode 4 is scraped off, and the corner is tapered. To

In the steps up to this point, the size of the heat acting portion 8 is 30 μm in width × 150 μm in length, and the resistance value including the electrode 4 is 100 μm.
Thermal energy generating means having a circuit pattern of Ω was formed on the substrate.

In this embodiment, as shown in FIG. 4, the input side electrode 12 is an individual electrode so that each of the thermal energy generating means can be selectively heated.
1 is a common electrode for simplifying the electrode configuration.

Next, as shown in FIG. 2D, an upper layer 5 made of SiO ₂ was formed on the thermal energy generating means to a thickness of 0.3 μm using an RF sputtering apparatus.
The forming conditions are RF power; 1 kW, pressure; 1 × 10 ⁻³ Torr.
Performed in

Then, in order to improve the cavitation resistance of the first protective layer 5, a second protective layer (not shown) made of Ta is formed on this protective layer 5 by using the same RF sputtering apparatus as described above. A substrate having a thickness of 5000 mm and comprising two protective layers was obtained. The protective layer thus obtained had good step coverage and was free from layer defects such as pinholes.

After the top plate 16 (material: glass) having the grooves shown in FIG. 3 described above is sufficiently aligned with the substrate on which the protective layer is formed as described above, the substrates are joined.
A liquid supply pipe 20 was further connected thereto to complete a liquid jet recording head as shown in FIG.

In FIG. 3, the liquid flow path 17 (width 40 μm)
m, a height of 40 μm) and a groove serving as the common liquid chamber 19 were formed by cutting the top plate 16 using a micro cutter. Also,
In FIG. 4, the individual electrode 12 and the common electrode 11
A lead substrate (not shown) having electrode leads for applying a desired pulse signal from outside the head is provided, and recording is performed based on the signal.

The ink jet recording head thus prepared has (1) reduced power consumption, (2) improved thermal responsiveness, and (3) driving with a shorter pulse width than the conventional one. , An improvement in performance such as good durability was observed. Further, based on the foaming stability by driving the short pulse, the ejection stability of the recording liquid was improved, and the recording quality was improved. Further, the printing durability was good.

(Example 2) Next, the second embodiment will be described with reference to materials and numerical values.

In this example, the liquid jet recording head shown in FIG. 4 was prepared as follows.

Referring to FIG. 5, first, a thermal oxidation thermal storage layer 2 made of SiO ₂ having a thickness of 5 μm was formed on a substrate 1 made of Si. Then, a heating resistance layer 3 made of HfB ₂ was formed to a thickness of 1300 ° by a sputtering method. Next, on the heating resistance layer 3, an Al conductor layer 4 'serving as the electrode 4 is formed.
Was formed to a thickness of 6000 ° by sputtering (FIG. 5).
(A)). Then, the resist is patterned by using a well-known photolithography (photolithography) technique, and the conductor layer 4 ′ and the heating resistance layer 3 are etched.

Next, as shown in FIG. 5B, a resist 6 having a desired pattern is formed on the conductor layer 4 'in order to obtain thermal energy generating means.

Next, using an ECR etcher, a mixed gas of BCl ₃ , Cl ₂ and O ₂ was used as an etching gas as shown in FIG.
As shown in (c), while the resist 6 is being receded, the conductor layer 4 ′ is formed.
Is etched by 0.3 μm, and the side surface of the etching hole is tapered.

Next, immersion treatment is carried out with a polymer removing solution SST-A1 (manufactured by Tokyo Ohka) containing dimethyl sulfoxide as a main component to remove the polymer adhered to the etching holes.

Next, as shown in FIG.
The remaining 0.3 μm conductor layer 4 ′ is wet-etched using a mixture of nitric acid, phosphoric acid and acetic acid as an etching solution without stripping. Thereafter, the resist 6 is stripped.

In the steps so far, the size of the heat acting portion 8 is 30 μm in width × 150 μm in length, and the resistance value including the electrode 4 is 100 μm.
Thermal energy generating means having a circuit pattern of Ω was formed on the substrate.

In this embodiment, as shown in FIG. 4, the input side electrode 12 is an individual electrode so that each of the thermal energy generating means can be selectively heated.
1 is a common electrode for simplifying the electrode configuration.

Next, as shown in FIG. 5D, an upper layer 5 made of SiO ₂ was formed to a thickness of 0.3 μm on the thermal energy generating means using an RF sputtering apparatus.
The forming conditions are RF power; 1 kW, pressure; 1 × 10 ⁻³ Torr.
Performed in

Thereafter, in order to improve the cavitation resistance of the first protective layer 5, a second protective layer (not shown) made of Ta is formed on this protective layer 5 by using the same RF sputtering apparatus as described above. A substrate having a thickness of 5000 mm and comprising two protective layers was obtained. The protective layer thus obtained had good step coverage and was free from layer defects such as pinholes.

After the top plate 16 (material: glass) having the above-described groove as shown in FIG. 3 is sufficiently aligned with the substrate on which the protective layer is formed as described above, it is joined.
A liquid supply pipe 20 was further connected thereto to complete a liquid jet recording head as shown in FIG.

In FIG. 3, the liquid flow path 17 (width 40 μm)
m, a height of 40 μm) and a groove serving as the common liquid chamber 19 were formed by cutting the top plate 16 using a micro cutter. Also,
In FIG. 4, the individual electrode 12 and the common electrode 11
A lead substrate (not shown) having electrode leads for applying a desired pulse signal from outside the head is provided, and recording is performed based on the signal.

The ink jet recording head thus prepared has (1) a reduction in power consumption, (2) an improvement in thermal responsiveness, and (3) a drive with a shorter pulse width than the conventional one. , An improvement in performance such as good durability was observed. Further, based on the foaming stability by driving the short pulse, the ejection stability of the recording liquid was improved, and the recording quality was improved. Further, the printing durability was good.

(Other Embodiments) Next, FIG. 7 is a schematic diagram showing an example of the configuration of an ink jet recording apparatus on which the above-described recording head is mounted. The head cartridge 601 mounted on the ink jet recording apparatus 600 shown in FIG.
And a liquid ejection head (see FIG. 4) formed by using the substrate shown in FIG. 1 for ejecting ink for print recording, and an ink tank for holding liquid supplied to the liquid ejection head. .

As shown in FIG. 7, the head cartridge 601 engages with the spiral groove 606 of the lead screw 605 which rotates via the driving force transmission gears 603 and 604 in conjunction with the forward and reverse rotation of the drive motor 602. Is mounted on a carriage 607. The head cartridge 601 is moved by the power of the drive motor 602 to the carriage 60.
7 is reciprocated along the guide 608 in the directions of arrows a and b. The inkjet recording apparatus 600 includes a recording medium transport unit (not shown) that transports a printing paper P as a recording medium that receives a liquid such as ink discharged from the head cartridge 601. The paper pressing plate 610 of the print paper P conveyed on the platen 609 by the recording medium conveying means presses the print paper P against the platen 609 in the moving direction of the carriage 607.

In the vicinity of one end of the lead screw 605, photocouplers 611 and 612 are provided. The photocouplers 611 and 612 are
07, the photocouplers 611 and 6
This is a home position detecting means for confirming the presence in the area No. 12 and switching the rotation direction of the drive motor 602. In the vicinity of one end of the platen 609, a support member 613 that supports a cap member 614 that covers the front surface of the head cartridge 601 having the discharge port is provided. In addition, an ink suction unit 615 that sucks ink that has been idly discharged from the head cartridge 601 and accumulated inside the cap member 614 is provided. The ink suction unit 615 performs suction recovery of the head cartridge 601 through the opening of the cap member 614.

The ink jet recording apparatus 600 has a main body support 619. The moving member 618 is attached to the main body support 619 in the front-rear direction,
It is supported so as to be movable in a direction perpendicular to the direction of movement 07. The cleaning blade 617 is attached to the moving member 618. Cleaning blade 6
Reference numeral 17 is not limited to this form, and may be another form of a known cleaning blade. Further, the ink suction means 6
15 is provided with a lever 620 for starting suction in the suction recovery operation by the lever 15. The lever 620 moves with the movement of the cam 621 engaging with the carriage 607, and the driving force from the driving motor 602 switches the clutch. The movement is controlled by a known transmission means such as the like. An ink jet recording control unit for giving a signal to a heating element provided in the head cartridge 601 and controlling the driving of each mechanism described above is provided on the recording apparatus main body side.
It is not shown in FIG.

In the ink jet recording apparatus 600 having the above-described configuration, the head cartridge 601 reciprocates over the entire width of the print sheet P with respect to the print sheet P conveyed on the platen 609 by the recording medium conveying means. When a drive signal is supplied from a drive signal supply unit (not shown) to the head cartridge 601 during this movement, ink (recording liquid) is ejected from the liquid ejection head unit to the recording medium in accordance with the signal, and recording is performed. Done.

The present invention provides an excellent effect particularly in an ink jet recording head and a recording apparatus in which a flying droplet is formed by utilizing thermal energy and recording is performed among the ink jet recording methods.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or liquid path in which This is effective because it generates heat energy in the electrothermal transducer, causing film boiling on the heat-acting surface of the recording head, and as a result, it is possible to form bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis. It is. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, The present invention also includes a configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which a heat acting portion is arranged in a bending region.

In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, or absorbs pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461, which discloses a configuration in which an opening corresponds to a discharge unit.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above specification. The present invention can exhibit the above-mentioned effects more effectively, though it may be either a configuration that satisfies the above requirements or a configuration as a single recording head that is formed integrally.

In addition, the print head is replaceable with a print head of a replaceable chip type, which can be electrically connected to the main body of the apparatus or supplied with ink from the main body of the apparatus. The present invention is also effective when a cartridge type recording head provided with an ink tank is used.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like provided as components of the printing apparatus of the present invention since the effects of the present invention can be further stabilized. If you list these specifically,
Capping means, cleaning means, pressurizing or suction means for the printhead, preheating means using an electrothermal transducer or another heating element or a combination thereof, and a preliminary ejection mode for performing ejection other than recording Is also effective for performing stable recording.

Further, the recording mode of the recording apparatus is not limited to a recording mode of only a mainstream color such as black, and may be a single recording head or a combination of a plurality of recording heads. The present invention is also extremely effective for an apparatus provided with at least one of full colors by color mixture.

In the embodiments of the present invention described above,
Although the ink is described as a liquid, it is an ink that solidifies at room temperature or lower, and softens at room temperature, or is a liquid, or in the inkjet method described above, the ink itself is heated to 30 ° C or more and 70 ° C or less. Generally, the temperature is adjusted within the range and the temperature is controlled so that the viscosity of the ink is in the stable ejection range. Therefore, it is sufficient that the ink is in a liquid state when the use recording signal is applied.

In addition, the temperature rise due to the thermal energy is positively prevented by using the energy of the state change from the solid state to the liquid state of the ink, or the ink is solidified in a standing state for the purpose of preventing the evaporation of the ink. Either ink may be used, or in any case, the ink may be liquefied by application of heat energy according to the recording signal and ejected as a liquid ink, or may already start to solidify when reaching the recording medium. The use of an ink having a property of being liquefied for the first time by thermal energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or Japanese Patent Application Laid-Open No. 60-71260, in which the porous sheet is opposed to the electrothermal converter while being held in a liquid or solid state in the concave portions or through holes of the porous sheet. It is good. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as a form of the recording apparatus according to the present invention, in addition to one provided as an image output terminal of an information processing apparatus such as a word processor or a computer as an integrated or separate apparatus, a copying apparatus combined with a reader, A facsimile apparatus having a transmission / reception function may be employed.

[0127]

As described above, according to the present invention, the edge portion of the electrode formed on the heating resistor layer has a vertical surface substantially perpendicular to the surface of the heating resistor layer and a vertical surface extending from this vertical surface to the upper surface of the electrode. It is possible to provide a head base formed of a continuous inclined portion. That is, since the corners of the steps formed by the heating resistance layer and the electrodes are cut off, the step coverage of the protective layer is improved. In addition, the length of the vertical surface of the electrode with respect to the surface of the heating resistor layer can be reduced, so that the protective layer can be made thinner.

However, since the change in the distance between the electrodes is smaller than that in the case where the edge portion is formed only by the inclined portion, the heating resistance value between the electrodes is stabilized. In addition, only the slanted portion creates a very thin portion on the electrode,
In the shape as described above, a certain thickness or more is secured, and the durability is improved.

By applying such a substrate for a recording head to a recording head, the printing durability is not deteriorated.
Not to mention the power saving of the inkjet recording head,
It is possible to increase the speed of thermal response, improve durability, improve ejection stability, improve recording quality, and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a substrate for an inkjet recording head obtained by a method according to a first embodiment of the present invention.

FIG. 2 is a process chart for explaining a head substrate forming method according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a top plate having a liquid flow path and a liquid chamber forming groove used in an example of an ink jet recording head obtained by applying the head substrate of the present invention.

FIG. 4 is a diagram showing a completed state of an example of an ink jet recording head obtained by applying the head substrate of the present invention.

FIG. 5 is a process chart for explaining a head substrate forming method according to a second embodiment of the present invention.

FIG. 6 is a diagram for explaining an etching failure due to polymer adhesion.

FIG. 7 is a diagram illustrating a configuration example of a recording apparatus on which the inkjet recording head of the present invention is mounted.

FIG. 8 is a plan view of a conventional substrate for an inkjet recording head.

9 is a sectional view taken along line X-X 'of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Heat storage layer 3 Heating resistance layer 4 Electrode 4 'Conductive layer 4a Vertical surface 4b Inclined part 4c Upper surface 5 Upper protective layer 6 Resist 8 Heat acting part 10 Step part 11 Common electrode 12 Individual electrode 16 Groove plate 17 Ink channel 19 Common liquid chamber 20 Ink supply pipe 21 Discharge port

Claims (6)

[Claims] 1. An ink jet recording head substrate comprising: a heating resistor layer; at least a pair of electrodes formed separately on the heating resistor layer; and a protective film covering the heating resistor layer and the electrodes. An ink-jet recording head substrate, wherein an edge portion of the electrode is formed of a surface substantially perpendicular to the surface of the heating resistor layer and an inclined portion continuous from the vertical surface to the upper surface of the electrode. . 2. A liquid discharge port for discharging a recording liquid, a thermal energy generating means for supplying a discharging energy to the recording liquid, and a protective layer covering the thermal energy generating means, In an ink jet recording head, wherein the energy generating means includes a heating resistor layer and at least a pair of electrodes formed apart from each other on the heating resistor layer, the edge of the electrode is positioned with respect to the surface of the heating resistor layer. An ink jet recording head, comprising: a substantially vertical surface; and an inclined portion continuous from the vertical surface to the upper surface of the electrode. 3. The method according to claim 1, wherein the heating resistance layer and the conductor layer are sequentially laminated on the substrate, and the heating resistance layer and the conductor layer are patterned. A step of patterning only the conductor layer on the heating resistance layer to form the electrode; a step of sputter etching the electrode; and forming an insulating protection layer to cover the electrode and the heating resistance layer. And a step of forming a substrate for an ink jet recording head. 4. The method according to claim 3, wherein the sputter etching gas contains argon as a main component. 5. The method according to claim 1, wherein the heating resistance layer and the conductor layer are sequentially laminated on the substrate, and the heating resistance layer and the conductor layer are patterned. A step of patterning only a conductor layer on the heating resistance layer to form the electrode; and a step of forming an insulating protective layer so as to cover the electrode and the heating resistance layer. Forming a resist pattern on the conductor layer in the step of patterning only the conductor layer on the resistance layer,
A method for producing a substrate for an ink jet recording head, characterized in that the conductor layer is partially etched by dry etching while the resist is receded, and then the electrodes are formed by performing wet etching. 6. The step of patterning only the conductor layer on the heat-generating resistor layer, wherein after performing dry etching halfway, the wet etching is performed after processing with a polymer removing liquid.
3. The method for producing a substrate for an ink jet recording head according to item 1.