JP3658221B2 - Ink jet recording head, head substrate, and method of manufacturing the substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording head that performs recording by discharging ink, the head substrate, a method for manufacturing the substrate, and an ink jet recording apparatus.
[0002]
[Prior art]
The ink jet recording system disclosed in US Pat. No. 4,723,129 or US Pat. No. 4,740,796 can perform high-speed, high-density, high-precision and high-quality recording, and is suitable for colorization and compactification. . A recording head that uses this ink jet recording method and foams ink using thermal energy to eject the ink onto a recording medium has the same heating resistor for foaming the ink and wiring that electrically connects to the heating resistor. In general, the ink jet recording head substrate is formed on the substrate, and nozzles for discharging ink are formed on the substrate.
[0003]
In addition, this inkjet recording head substrate is used in various ways in order to save labor of electric energy input on the one hand, and on the other hand, to prevent mechanical damage caused by ink foaming and a decrease in the life of the substrate due to destruction of the heat generating part due to heat pulses. Ingenuity has been made. In particular, many contrivances have been made for the protective film that protects the heat generating resistor having the heat generating portion located between the pair of wiring patterns from ink.
[0004]
From the viewpoint of heat efficiency, it is advantageous that the protective film has a high thermal conductivity or is thin. On the other hand, a thicker layer is advantageous from the viewpoint of the probability of mechanical damage and film defects accompanying ink foaming. Furthermore, the protective film also serves to protect the wiring connected to the heating resistor from ink, and in terms of thickness, the protective film is further restricted by the purpose of protecting the wiring portion rather than the heating resistor portion.
[0005]
In detail, the surface of the heating resistor is generally very smooth and the protective film thereon can be densely formed. On the other hand, the wiring is generally made of Al, and the surface of the Al is as manufactured. It is easily affected by heat, the surface is relatively uneven, and the thickness of Al is about 500 nm, so the quality of the protective film of the stepped portion tends to deteriorate. In view of the above, the protective film is required to have a certain thickness, in fact, about 1 μm.
[0006]
In order to make the protective film on the heating resistor as thin as possible and stabilize the protective function on the wiring, Japanese Patent Application Laid-Open No. 08-112902 discloses a method of partially thinning the protective film on the heating resistor. Is described. In this method, by reducing only the thickness of the protective film on the heating resistor, it is possible to achieve a reduction in energy input and stabilization of the life.
[0007]
However, in this example, first, the heating resistor and the wiring pattern are formed on the underlying silicon oxide film, then silicon oxide is formed as the first protective film, and then the heating resistor generates heat by patterning. In order to partially remove the protective film on the part and finally form silicon nitride as the second protective film, there are the following problems.
[0008]
The partial protection film is usually removed by wet etching. As the etching solution, if the first protective film is silicon oxide, a hydrogen fluoride-based etching solution is used. The heating resistor is generally made of HfB ₂ or TaN, but these are not damaged by the hydrogen fluoride type etching solution.
[0009]
Here, when the part where the protective film is locally removed is located about several μm inside the heating resistor area of the heating resistor, there is no problem in the manufacturing process, but a relatively small area inside the entire area of the heating part. Therefore, the thermal efficiency is lowered.
[0010]
On the other hand, the quality of the protective film of the first layer formed while covering the step between the wiring and the heating resistor and the underlying substrate may be deteriorated at the step. Therefore, if the first protective layer is removed wider than the heating part of the heating resistor, the vicinity of the step between the heating resistor and the substrate below it will be etched, so along the step part having a relatively poor film quality. As a result, undercutting progresses and voids are generated inside the film, resulting in a problem that the life of the head substrate may be reduced. Here, the reason why the first layer film quality of the stepped portion is deteriorated is that vertical etching is often used for miniaturization as etching of the heating resistor, and the fact that the cross section is substantially 90 ° is also a factor. it is conceivable that. Therefore, in order to eliminate undercut as much as possible, it is necessary to strictly control the etching time of the first protective film.
[0011]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional problems, use the heat generating part of the heat generating resistor as widely as possible, and have a high thermal efficiency and an energy saving structure, but the process management is easy and the life is long, and the head And a manufacturing method of the substrate and an ink jet recording apparatus.
[0012]
[Means for Solving the Problems]
The inkjet recording head of the present invention protects a heating resistor that forms a heating portion on a substrate, wiring that is electrically connected to the heating resistor, and the heating resistor and the wiring. An ink jet recording head having an ink path communicating with an ejection port for ejecting ink on an ink jet recording head substrate having a protective film provided therefor, wherein the protective film includes the heating resistor and the heating resistor. A first layer protective film covering the wiring, and an opening formed on the first layer protective film with a material different from the first layer protective film and corresponding to the heat generating portion of the heat generating resistor; A second layer protective film made of an inorganic material, and a third layer protective film of the same material system as the first layer protective layer covering the second layer protective film and the first layer protective film exposed from the opening; , Including.
[0013]
In addition, the inkjet recording head substrate of the present invention includes a heating resistor layer provided on a silicon substrate and a pair formed on the heating resistor layer with a portion serving as a heating portion being spaced apart. a wiring layer electrically connected to a substrate for an ink jet recording head having a protective film covering said wiring layer on said heat generating resistor layer and the heat generating resistor layer, said protective film, said A first layer protective film covering the heating resistor layer and the wiring layer; and a step formed on an end of the wiring layer and the heating resistor layer from above the one layer protective film ; a second layer protective film provided so as to have a opening at a position corresponding to the section, said the two-layer protective film, said first layer protecting film through the opening, a third stacked in contact with the It has a layer protecting film; wherein said first layer protecting film third layer protective film and the same first A silicon compound, and wherein the second layer protective film is composed of a large etching rate material than the etch rate of the a different second silicon compound first silicon compound and the first silicon compound To do.
[0014]
The method for producing a substrate for an ink jet recording head according to the present invention includes a heating resistor layer provided on a silicon substrate and a pair of heating resistors layered on the heating resistor layer with a portion serving as a heating portion being separated. A method for manufacturing an ink jet recording head substrate, comprising: a wiring layer electrically connected to a body layer; and a protective film covering the heating resistor layer and the wiring layer on the heating resistor layer , the heating resistor layer and forming a first layer protecting film made of the first silicon compound covering said interconnection layer, from the top of the first layer protecting film, the heat generating resistor and the end of the wiring layer covers the step portion is formed in the layer, so as to have an opening at a position corresponding to the heating unit, first of the first greater etch rate than the etch rate of the silicon compound and the first silicon compound Unlike 2 silico Forming a second layer protective film made of a compound,
And having said second layer protecting film and said first layer protecting film through the opening, and a step of laminating a third layer protective film consisting of the first silicon compound in contact with the .
[0015]
In addition, an ink jet recording apparatus of the present invention includes the above ink jet recording head and a member for mounting the ink jet recording head.
[0016]
In the present invention as described above, since the first layer protective film covers the heating resistor and the wiring, the step difference at the corners of the heating resistor and the wiring pattern is alleviated. Therefore, the film quality of the second layer protective film formed thereon is improved, and even if the second layer protective film is etched, overetching does not substantially proceed along the stepped portion.
[0017]
The third layer protective film of the same material system as the first layer protective film is combined with the first layer protective film remaining on the heat generating part to form a protective film for the heat generating part, while on the wiring, the first layer protective film and A protective film having at least a three-layer structure is formed on the second protective film. As described above, since the film is formed by being divided into a plurality of layers, even if there is a defect somewhere in the protective film of one layer, the probability that a defect will occur somewhere in the entire protective film having a multi-layer structure is extremely high. Can be small.
[0018]
As described above, according to the present invention, it is possible to provide an ink jet recording head, a head substrate, a method for manufacturing the substrate, and an ink jet recording apparatus that combine energy saving, life stability, and process management simplicity.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The inkjet recording head according to the present invention protects a heating resistor that forms a heating portion on a substrate, wiring that is electrically connected to the heating resistor, and the heating resistor and wiring on the heating resistor. And an ink path that communicates with an ejection port for ejecting ink, on a substrate for an inkjet recording head having a protective film. The protective film is a first layer protective film that covers the heating resistor and the wiring, and a portion that is formed on the first layer protective film with a material different from that of the first layer protective film and that corresponds to the heating portion of the heating resistor. A third layer of the same material system as the first layer protective layer covering the second layer protective film made of an inorganic material having an opening in the first layer protective film and the second layer protective film and the first layer protective film exposed from the opening And a protective film.
[0020]
In the present invention, the material of the second layer protective film is formed of a material different from that of the first layer protective film mainly for manufacturing reasons. Usually, since the opening of the second layer protective film is formed by etching, the second layer protective film is preferably formed of a material that is more easily etched than the first layer protective film. That is, it is preferable to select a material such that the etching rate of the second layer protective film material is higher than that of the first layer protective film material, and in particular, the selectivity (the etching rate of the second layer protective film material / the first layer covering film). The etching rate of the material is preferably 10 or more, and more preferably 20 or more.
[0021]
In the present invention, the first layer protective film and the third layer protective film are made of the same material system mainly from the viewpoint of adhesion strength between the films in the opening of the heat generating portion. Here, the second layer protective film is formed of a material different from that of the first layer protective film and the third layer protective film as described above, but from the same material system as the first layer protective film and the third layer protective film. It is preferable to become. The “same material system” is particularly preferably a material containing silicon. As such a material, it is preferable that the first layer protective film and the third layer protective film are formed of silicon nitride and the second layer protective film is formed of silicon oxide.
[0022]
It is preferable to form the second layer covering film with silicon oxide containing boron or phosphorus because the difference in etching rate from the silicon nitride film can be further increased. In the present invention, the thickness of the first protective film is usually 0.01 to 0.5 μm, preferably 0.01 to 0.1 μm. The film thickness of the second layer protective film is usually 0.3 to 1.5 μm, preferably 0.5 to 1.0 μm. The film thickness of the third layer protective film is usually 0.1 to 1.0 μm, preferably 0.1 to 0.5 μm.
[0023]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[0024]
(Example 1)
FIG. 2 is a schematic top view showing the main part of the ink jet recording head substrate of the present invention. FIG. 1 is a schematic side cross-sectional view taken along the one-dot chain line X1-X2 in FIG.
[0025]
As shown in FIGS. 1 and 2, a silicon oxide film is formed as a heat storage layer 12 on a Si substrate 11, and an Al layer as a heating resistor layer 13 and a wiring 14 is formed in a predetermined pattern shape on the silicon oxide film. Is formed. A portion of the heating resistor layer 13 in the gap between the pair of wirings 14 becomes a heating portion 20.
[0026]
A silicon nitride layer is formed as the first layer protective film 15 so as to cover the heat generating resistor layer 13 and the wiring 14, a silicon oxide layer is formed as the second layer protective film 16 having an opening on the heat generating portion 20 of the heat generating resistor layer, As the third protective film 17, a silicon nitride film, and further a Ta film of the anti-cavitation film 18 mainly for protection from impact and cavitation destruction during foaming and defoaming are formed in order.
[0027]
A method for manufacturing an ink jet recording head substrate having this structure will be described with reference to FIGS. 3 and 4A to 4G.
[0028]
As shown in FIG. 3A, a silicon oxide film serving as a heat storage layer 12 as a base of the heating resistor is formed on the Si substrate 11 by thermal oxidation, sputtering, CVD, or the like.
[0029]
Next, as shown in FIG. 3B, the TaN layer 13a to be the heating resistor layer 13 is about 100 nm thick on the heat storage layer 12 by reactive sputtering, and the Al layer 14a to be the wiring 14 is 500 nm thick by sputtering. To form.
[0030]
Next, the Al layer 14a is wet-etched by photolithography, and the TaN layer 13a is reactive-etched. The cross-sectional shape is as shown in FIG. 3C (see FIG. 1 for the planar shape). The wiring 14 and the heating resistor layer 13 are formed. In the heat generating portion 20, the Al layer 14a is removed and the heat generating resistor layer 13 is exposed, and heat is generated when a current is passed through the wiring pattern 14.
[0031]
Next, as shown in FIG. 3D, a silicon nitride film is formed to a thickness of 200 nm as the first layer protective film 15, and a silicon oxide film 16a to be the second layer protective film 16 is formed to a thickness of 500 nm by the CVD method. .
[0032]
Next, using a photolithography method, the silicon oxide film 16a on the heat generating portion 20 of the heat generating resistor is partially etched using a hydrogen fluoride solution to form the second layer as shown in FIG. A protective film 16 is formed. At this time, a step 30 is formed.
[0033]
Next, as shown in FIG. 4F, silicon nitride is formed as a third layer protective film 17 to a thickness of 300 nm using a CVD method.
[0034]
Next, as shown in FIG. 4G, Ta as the anti-cavitation film 18 is formed to a thickness of 200 nm by a sputtering method.
[0035]
Finally, the Ta film and the first to third layer protective films are etched by photolithography to expose the electrode pads by the Al electrodes necessary for connection to the external power source, thereby manufacturing the main part of the substrate for the ink jet recording head. To complete.
[0036]
As a result of assembling an ink jet head using the ink jet recording head substrate thus manufactured and confirming its performance, power saving and a long life could be achieved.
[0037]
(Example 2)
An ink jet recording head was manufactured in the same manner as in Example 1 except that silicon oxide doped with boron or phosphorus was used as the second layer protective film. As a result, the etching rate with respect to the hydrogen fluoride solution was increased, and the selectivity with respect to silicon nitride as the material of the first layer protective film was further increased. As a result, damage to the first layer protective film that occurs during etching of the second layer protective film is reduced, so that the second layer protective film can be further thickened. Therefore, the wiring layer can be more reliably protected while saving power.
[0038]
In the above embodiment, an integrated circuit for driving the heating resistor may be built in the same Si substrate as in US Pat. No. 4,429,321. In this case, the integrated circuit portion is preferably covered with the first layer protective film, the second layer protective film, and the third layer protective film, similarly to the wiring portion.
[0039]
(Other examples)
Hereinafter, an inkjet head and an inkjet apparatus to which the inkjet head substrate of the present invention can be applied will be described. FIG. 5 is a schematic partially broken perspective view showing such an ink jet head. An inkjet head including an electrothermal transducer 1103, a wiring 1104, a liquid path wall 1105, and a top plate 1106 formed on a substrate 1102 through a semiconductor process such as etching and vapor deposition sputtering is shown. .
[0040]
The recording liquid 1112 is supplied from a liquid storage chamber (not shown) through the liquid supply pipe 1107 into the common liquid chamber 1108 of the head 1101. In the figure, reference numeral 1109 denotes a liquid supply pipe connector. The liquid 1112 supplied into the common liquid chamber 1108 is supplied into the liquid passage 1110 by a so-called capillary phenomenon, and is stably held by forming a meniscus on the discharge port surface (orifice surface) at the front end of the liquid passage.
[0041]
Here, when the electrothermal transducer 1103 is energized, the liquid on the surface of the electrothermal transducer is heated suddenly, bubbles are generated in the liquid path, and the liquid is discharged from the discharge port 1111 by the expansion and contraction of the bubbles. A droplet is formed.
[0042]
FIG. 6 is a schematic perspective view showing a main part of an ink jet apparatus to which the present invention is applied. The carriage HC that engages with the spiral groove 5005 of the lead screw 5004 that rotates via the driving force transmission gears 5011 and 5009 in conjunction with forward and reverse rotation of the drive motor 5013 has a pin (not shown), and is in the direction of the arrow. Is reciprocated. Reference numeral 5002 denotes a paper pressing plate that presses the paper against the platen 5000 in the carriage movement direction. Reference numerals 5007 and 5008 denote home position detecting means for confirming the presence of the carriage lever 5006 in this region by a photocoupler and switching the rotation direction of the motor 5013 and the like.
[0043]
Reference numeral 5016 denotes a member that supports a cap member 5022 that caps the front surface of the recording head. Reference numeral 5015 denotes suction means for sucking the inside of the cap, and performs suction recovery of the recording head through the cap opening 5023. Reference numeral 5017 denotes a cleaning blade, and reference numeral 5019 denotes a member that enables the blade to move in the front-rear direction, and these are supported by a main body support plate 5018. Needless to say, the blade is not in this form, and a known cleaning blade can be applied to this example. Reference numeral 5012 denotes a lever for starting suction for suction recovery. The lever 5012 moves with the movement of the cam 5020 engaged with the carriage, and the driving force from the drive motor is controlled by a known transmission means such as clutch switching. The
[0044]
These capping, cleaning, and suction recovery are configured so that desired processing can be performed at their corresponding positions by the action of the lead screw 5004 when the carriage comes to the home position side region. Any operation can be applied to this example as long as the operation is performed. The apparatus includes a drive signal supply unit for driving an energy generating element that generates energy used to eject ink.
[0045]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an ink jet recording head, a head substrate, a method for manufacturing the substrate, and an ink jet recording apparatus that have both energy saving, life stability, and ease of process management. it can.
[Brief description of the drawings]
FIG. 1 is a schematic sectional side view showing an example of a substrate for an ink jet recording head of the present invention.
FIG. 2 is a schematic top view showing an example of a substrate for an ink jet recording head of the present invention.
FIG. 3 is a schematic cross-sectional side view illustrating a manufacturing process of an ink jet recording head substrate of the present invention.
4 is a schematic cross-sectional side view showing the manufacturing process of the ink jet recording head substrate of the present invention, following FIG. 3. FIG.
FIG. 5 is a schematic partially broken perspective view showing a main part of the ink jet recording head of the present invention.
FIG. 6 is a schematic perspective view showing a main part of the ink jet recording apparatus of the present invention.
[Explanation of symbols]
11 Si substrate 12 Thermal storage layer (silicon oxide)
13 Heating resistor 13a TaN layer 14 Wiring pattern 14a Al layer 15 First layer protective film (silicon nitride)
16 Second layer protective film 16a Silicon oxide film 17 Third layer protective film (silicon nitride)
18 Anti-cavitation film (Ta)
20 Exothermic part 30 Step

Claims (7)

A heating resistor layer provided on the silicon substrate; a wiring layer laminated on the heating resistor layer with a portion serving as a heating portion being separated; and the heating layer electrically connected to the heating resistor layer; a protective film covering the resistor layer and the wiring layer on the heat generating resistor layer, a substrate for an ink jet recording head having,
The protective film is
A first layer protective film covering the heating resistor layer and the wiring layer ;
From the top of the first layer protecting film, covering a step portion formed at an end of the wiring layer and the heating resistor layer, a second that is provided so as to have a opening at a position corresponding to the heating unit A layer protective film;
Said second layer protecting film and said first layer protecting film through the opening, and a third layer protective film laminated in contact with,
Have
The first layer protective film and the third layer protective film are made of the same first silicon compound, and the second layer protective film is a second silicon compound different from the first silicon compound, An ink jet recording head substrate comprising a material having an etching rate higher than that of one silicon compound . 2. The ink jet recording head substrate according to claim 1, wherein the first silicon compound is silicon nitride and the second silicon compound is silicon oxide . 2. The ink jet recording head substrate according to claim 1, wherein the first silicon compound is silicon nitride, and the second silicon compound is made of silicon oxide containing boron or phosphorus . Wherein on the third layer protective film, an ink jet recording head substrate according to any one of claims 1 to 3, characterized in that anti-cavitation film is further provided. 5. The inkjet recording head substrate according to claim 4, wherein the cavitation-resistant film is made of tantalum . 6. An ink jet recording head, comprising: an ink jet recording head substrate according to claim 1, wherein an ink path communicating with an ejection port for ejecting ink is provided on the ink jet recording head substrate . A heating resistor layer provided on the silicon substrate; a wiring layer laminated on the heating resistor layer with a portion serving as a heating portion being separated; and the heating layer electrically connected to the heating resistor layer; A protective film covering the resistor layer and the wiring layer on the heating resistor layer , and a method for manufacturing an ink jet recording head substrate,
Forming a first layer protective film made of a first silicon compound covering the heating resistor layer and the wiring layer ;
The first silicon is formed so as to cover a step portion formed by an end of the wiring layer and the heating resistor layer from above the first layer protective film and to have an opening at a position corresponding to the heating portion. a compound forming a second layer protective film made of the second silicon compound of greater etch rate than the etch rate of the first silicon compound Unlike,
Laminating a third layer protective film made of the first silicon compound in contact with the second layer protective film and the first layer protective film through the opening;
A method for producing a substrate for an ink jet recording head, comprising:

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