JP2000168088A - Heating resistor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating resistor having a protecting film of a film thickness of 100-500 Å and a high resistance to cavitation damage and electrolytic etching and its manufacture. SOLUTION: An approximately 7000 Å film of a double-layer structure of TaSiO is first formed by a thin film formation technique, on which an electrode film is formed. An electrode pattern of a common electrode 18 and an individual wiring electrode 21 is formed to the electrode film by a photolithographic technique, and a heating element pattern of a 40 μm×40 μm heating part 22 is formed to a resistor film of the double-layer structure. An Si/Ta mole ratio of an upper layer 22b of the resistor film of the double-layer structure is set smaller than an Si/Ta mole ratio of a lower layer 22a. The upper layer 22b including much Ta is oxidized with heat by annealing (heat treatment) for 10 minutes at a substrate temperature of 400 deg.C. In consequence, a 100-500 Åautoxidation protecting layer 22b-1 of a TaSiO film is formed on the heating part 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating resistor which is resistant to cavitation damage and electrolytic corrosion and generates bubbles with high thermal efficiency.

[0002]

2. Description of the Related Art In recent years, ink jet printers have been widely used. The ink jet printers include a thermal jet method in which ink droplets are ejected by the force of air bubbles and a piezo method in which ink droplets are ejected by deformation of a piezoresistive element (piezoelectric element).

[0003] In these methods, a process in which ink as a color material is formed into ink droplets and directly ejected toward recording paper requires a lower printing energy as compared with an electrophotographic system using a toner as a powdery printing material. It is easy to colorize by mixing ink, and it is possible to reduce the size of printing dots, so that high image quality is achieved, the amount of ink used for printing is not wasted, and cost performance is excellent. This is the printing method used.

[0004] The above-mentioned thermal jet system has two configurations depending on the ejection direction of ink droplets. That is, there is a configuration that discharges in a direction parallel to the heating surface of the heating element, and a configuration that discharges in a direction perpendicular to the heating surface of the heating element.

FIGS. 8 (a), 8 (b) and 8 (c) show a structure in which the ink is discharged in a direction parallel to the heating surface of the heating element.
(f) schematically shows a configuration in which the liquid is discharged in a direction perpendicular to the heat generating surface of the heat generating element. Figure (a) or
As shown in FIG. 1D, a heating element 2 is formed on a silicon substrate 1. The heating element 2 is formed on the side of the heating element 2 in FIG. An orifice 4 is formed. The heating element 2 is connected to an electrode (not shown), and the ink 5 is always supplied to the ink flow path where the heating element 2 is provided.

In order to discharge ink droplets from the orifice 4, first, as shown in FIG. 2B or 2E, the heating element 2 is heated by energization according to image information, and Nucleus bubbles are generated, and the nucleus bubbles are united to form a film bubble 6. The film bubble 6 adiabatically expands and grows to push the surrounding ink, whereby the ink 5 'is pushed out from the orifice 4. The pushed ink 5 'is ejected from the orifice 4 toward the paper surface as an ink droplet 7, as shown in FIG. 7 (c) or (f). After that, the grown film bubble is shrunk by the heat of the surrounding ink, and finally the film bubble disappears and waits for the next heating element to be heated. This series of steps is performed instantaneously.

The above-described structure in which ink droplets are ejected in a direction perpendicular to the heat-generating surface of the heat-generating element is called a roof-shooter type thermal ink-jet head, and it is known that power consumption is extremely small. . As a method of manufacturing a thermal ink jet head for full color in this type, a method in which a plurality of heating elements, individual driving circuits, and orifices are collectively formed monolithically by utilizing a silicon LSI forming technique and a thin film forming technique. is there.

According to this method, for example, in the case of a print head having a resolution of 360 dpi (dots / inch), 128 heating elements, drive circuits, and orifices are formed on a substrate having a width of about 10 mm. In the case of 720 dpi, 256 heating elements, drive circuits, and orifices are formed.

Incidentally, the film boiling phenomenon is utilized in the above-mentioned steps (1) to (4). The film boiling phenomenon occurs when an object heated to a high temperature, such as quenching of iron, is immersed in a liquid, and when the surface temperature of the object in contact with the liquid is rapidly increased. The film boiling phenomenon used in the method is based on the latter method of "rapidly increasing the surface temperature of an object in contact with a liquid". In the film boiling phenomenon, a phenomenon that occurs when the bubbles generated in the liquid disappears is called cavitation.

FIGS. 9 (a) and 9 (b) are diagrams schematically showing the process of growth and extinction of bubbles related to the ejection of ink droplets.
FIG. 5A shows the heating element 2 experimentally set in an open pool 8 having a water depth of 1 mm (millimeter), and the process of the growth and extinction of bubbles caused by the heating element 1 from 0 to 6 μs (microsecond).
It is shown for each s. FIG. 2B shows the timing of energizing the heating element 2.

As shown in FIG. 1A, the heating element 2 is heated in 0 to 1 μs, nuclear bubbles grow in 1 to 2 μs, and 2 μs
A bubble for ejecting ink droplets is generated during the period from 3 μs to 3 μs, and the contraction of the bubble has already started at 3 μs. Until the bubble disappears in 6 μs, the arrow a- in FIG.
As shown by 1, a-2 and a-3, cavitation with negative pressure occurs.

The destructive force due to the cavitation acts as a force for peeling the heating element 2 from the installation surface. It is said that the impact force reaches 1000 ton / cm ² in the case of the above-mentioned open pool having a depth of 1 mm.

The area of the heat generating element of the thermal ink jet head is about 40 μm × 40 μm. When converted by this area ratio, the impact force is about 16 kg (kilogram). In order to prevent the occurrence of cavitation damage, as a general method,
It has been practiced to provide a cavitation damage preventing layer on the heating element surface.

FIG. 10 is a diagram schematically showing such a conventional heating element. As shown in the drawing, a Ta-Si-O layer 2a formed on a silicon substrate (not shown) has a heating element 2 sandwiched between a common electrode 9a and an individual wiring electrode 9b.
(A heat generating portion of the Ta-Si-O layer 2a).
On this heating element 2, a self-oxidized film 2b is formed as a cavitation damage preventing layer.

The above-mentioned thermal ink jet head is formed monolithically on a silicon substrate, and the size of the heating element is about 40 μm × 40 μm.
40 μm. On this, a self-oxidized film is formed by thermal oxidation. The thickness of this self-oxide film is several tens of millimeters.
In the case of a monolithic structure, the heating temperature has a limit of about 400 ° C., and it is not possible to increase the heating temperature further to increase the film thickness.

[0016]

However, it has been found that a protective film having a thickness of at least 100.degree. Is required in order to manufacture a thermal ink jet head having higher reliability, that is, a lower damage occurrence rate. . Therefore, the above-mentioned self-oxidized film has a problem that the film thickness is too thin.

For this reason, it has been necessary to form a dedicated protective film using a suitable material other than the self-oxidizing film. As such a dedicated protective film material, silicon oxide (S
iO2), magnesium oxide (MgO), aluminum oxide (AlO3), tantalum oxide (TaO), zirconium oxide (GrO) and the like are known.

The thickness of the protective film is not good if it is too thick. If it is too thick, the heat generating efficiency of the heating element due to the generation of air bubbles is reduced, and the energy loss is increased, which is extremely uneconomical. Therefore, it is desirable that the thickness is at most 500 ° or less, but none of the above protective film materials is practically usable as a protective film at a thickness of 500 ° or less. In addition, there is no report that a film having a thickness of 500 ° or less can be used as a protective film.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances,
An object of the present invention is to provide a heating resistor provided with a protective film having a film thickness of 100 to 500 mm and having strong resistance to cavitation damage and electrolytic corrosion, and a method for manufacturing the same.

[0020]

First, a plurality of heating resistors according to the first aspect of the present invention are provided on a substrate and generate air bubbles at an interface with the supplied ink by generating heat, thereby forming a corresponding nozzle. A heating resistor of a thermal inkjet head for ejecting ink droplets from a hole, wherein the first Ta-Si
And a second Ta-Si layer laminated on the first Ta-Si-O layer and having a Si / Ta molar ratio smaller than the Si / Ta molar ratio of the first Ta-Si-O layer. -O layer and the second
And an oxide layer formed on the Ta-Si-O layer.

In the first Ta-Si-O layer, the composition may be such that the composition has a molar ratio of Si to Ta of Si / Ta of "0.47 <Si / Ta <0.75". Further, it is preferable that the constitution is such that “25 mol% ≦ O ≦ 40 mol%”. In the second Ta-Si-O layer, for example, in the composition, the molar ratio of Si to Ta, Si / Ta, is "0 <Si / Ta ≦ 0.1".
5 ". Also, the oxide layer has a thickness of 100, for example.
It is configured to be {-500}.

Next, a method for manufacturing a heating resistor according to a fifth aspect is a method for manufacturing a heating resistor for a thermal ink jet head, wherein a first target having a predetermined amount of Si embedded in a Ta plate is used. To form a first Ta-Si
A first sputtering step of forming a -O layer, and the above-described method using a second target in which a smaller proportion of Si than the first target is embedded in a Ta plate on the first Ta-Si-O layer. A second Ta layer is formed on the first Ta-Si-O layer.
A second sputtering step of forming a -Si-O layer;
An annealing step of forming a thermal oxide film in a region to be a heat generating portion on the second Ta-Si-O layer.

The first target has a Si / Ta molar ratio of 1/3, and the second target has a Si / Ta molar ratio of 1/9.
It is preferred that In the first and second sputtering steps, for example, both the degree of vacuum is 1.times.10@-6 Torr or less and the substrate temperature is 15.degree.
0 ° C. to 400 ° C., film formation rate 15 ° / min.
min, in an argon gas atmosphere. Further, the annealing step is a heat treatment at 400 ° C. for 10 minutes, for example, as described in claim 8, and is preferably performed after the wiring pattern is formed on the heat generating portion.

As a result, a heating element having a protective layer that generates bubbles with high energy efficiency and is less susceptible to cavitation damage and electric corrosion is realized.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a diagram showing a full-color thermal inkjet head (hereinafter, simply referred to as a color head) according to an embodiment, and FIG. 1B is a diagram showing a number of such color heads formed on a silicon wafer. It is a figure showing a state. The color head 10 shown in FIG. 1A has a shape in which four single heads 12 (12a, 12b, 12c, 12d) are arranged on a slightly large substrate 11.

In each of the single heads 12, a single nozzle row 13 composed of a number of nozzles (orifices) is formed on an orifice plate 14, and the color head 10 as a whole has four nozzle rows 13 Are formed. These nozzle rows 13 are dedicated to, for example, three colors of yellow (Y), magenta (M), and cyan (C), which are three subtractive primary colors, and black portions of characters and images in order from right to left. Black (Bk) ink to be ejected.

Such a color head 10 has a resolution of approximately 8.5 mm × 19.
128 nozzles x 4 rows = 64 for a chip of size 0mm
0 nozzles and a resolution of 7
In the case of 20 dpi, approximately 8.5 mm × 19.0
256 nozzles x 4 rows = 1280 mm chips
It is possible to form a nozzle.

Then, as shown in FIG. 2B, a large number of such color head substrates (for example, 90 pixels) are divided on one silicon wafer 15 by scribe lines.
(A) or more, and are completed as shown in FIG. 7A through a manufacturing process to be described later, and are individually cut out from the silicon wafer 15.

FIG. 2A is a view showing the first step of the above-mentioned color head 10 manufacturing process. The upper part shows a plan view, the middle part shows an AA 'cross-sectional view of the upper part, The lower section shows an BB 'cross-sectional view of the upper section. FIG. 2 (b)
Shows a step following FIG. 2 (a), and the parts shown in the upper, middle and lower parts thereof correspond to the parts shown in the upper, middle and lower parts of FIG. 2 (a). And FIG. 2 (c)
It is a figure which shows the last process, FIG.1 (a) is expanded and shown in the upper stage. The parts shown in the upper, middle, and lower sections correspond to the upper, middle, and lower sections in FIG. 2A. 2 (a), 2 (b) and 2 (c), for convenience of illustration, 128 or 256 heating elements and orifices are represented by 5 heating elements and orifices. Is shown.

Hereinafter, referring to FIGS. 2 (a), (b) and (c),
A method of manufacturing the color head 10 will be described first from a basic manufacturing method. First, as a step 1, a drive circuit and its terminals are formed by an LSI forming process and a passivation film having a thickness of 1 to 2 μm is formed on each substrate partitioned on a silicon wafer of 4 inches or more. A contact hole is formed in the terminal and an unnecessary portion of the passivation film is removed.

Next, in step 2, a heating resistor film for forming a heating element made of Ta—Si—O is formed to a thickness of 4000 ° by using a thin film forming technique such as a sputtering technique. An electrode film for forming individual wiring electrodes is formed. This electrode film is made of W-Al (or W-
Au, a barrier metal film made of Ti, W-Si), etc.
It is preferable to form a multi-layer structure in which electrode films are laminated. Then, the electrode film (and the barrier metal film if a barrier metal film is formed) is formed by photolithography.
A wiring portion pattern is formed, and a square exposed portion of, for example, approximately 40 μm × 40 μm is formed on the heating resistor film. Thereby, a fine pattern of the heating element (heating section) is formed.

FIG. 2A shows a state immediately after the steps 1 and 2 are completed. That is, a drive circuit 16 and its terminals 17 (see FIG. 1A) are formed on the substrate 11, and a common electrode 18 (18a, 18b), a common electrode power supply terminal 19 (see FIG. 1A), Individual wiring electrode 21,
Many heating elements 22 are formed.

Subsequently, in step 3, the individual heating elements 2
After forming a partition member made of an organic material such as photosensitive polyimide to a height of about 20 μm by coating to form an ink path corresponding to 2, and patterning this,
30 minutes to 60 minutes, optionally 2 hours, 300 ° C. to 40
Curing (dry curing, baking) by applying heat of 0 ° C. is performed, and a 10 μm-high partition wall made of the photosensitive polyimide after curing is formed and fixed on the substrate 11.

Further, in step 4, a groove-like ink supply path is formed on the surface of the substrate 11 by wet etching or sand blasting, and an ink supply hole communicating with the ink supply path and opening on the lower surface is formed. I do.

FIG. 2B shows a state immediately after Steps 3 and 4 are completed. That is, a groove-shaped ink supply path 23 and a cylindrical ink supply hole 24 are formed,
The common electrode 18 (18) located on the left side of the ink supply path 23
a), a portion where the individual wiring electrode 21 on the right side is disposed, and between each heating element 22, a partition wall 25 (25, 25).
-1, 25-2) are formed. This partition 25
If the portion 25-1 on the individual wiring electrode 21 is a comb body,
A portion 25-2 extending between the heating elements 22 has a shape corresponding to the teeth of a comb.

As a result, the fine individual ink paths in which the heating elements 22 are located at the roots between the teeth are formed by the number of the heating elements 22 using the teeth of the comb as partition walls. By changing the length of the teeth of the comb, the conductance of the flowing ink changes, and the interference between the ink flowing in adjacent individual ink paths is also affected.

Thereafter, in step 5, an orifice plate of a film of polyimide having a thickness of 10 to 30 μm is coated on one side with a very thin thermoplastic polyimide as an adhesive, for example, to a thickness of 2 to 5 μm. The ink path formed by the partition wall 25 is covered with the uppermost layer of the laminated structure, thereby forming a fine individual ink path and a common ink path. Then, pressure is applied while heating at 200 to 300 ° C. to fix the orifice plate. Subsequently, a thickness of 0.5, such as Ni, Cu or Al, is formed on the orifice plate surface.
A metal film having a thickness of about 1 μm is formed.

Further, in step 6, the metal film on the orifice plate is patterned to form a mask for selectively etching the polyimide, and then the orifice plate is subjected to the above-mentioned etching by a helicone wave etching device or the like. A plurality of nozzle holes (orifices) are formed at a time by making holes of 40 μmφ to 20 μmφ according to the metal film mask.

FIG. 2C shows a state immediately after the completion of the steps 5 and 6. That is, on the uppermost layer of the substrate 11, the orifice plate 14 coated with a thermoplastic polyimide 26 on one surface is laminated so as to cover the entire area except for the drive circuit terminal 17 and the common electrode power supply terminal 19, thereby forming the above-described ink. The passage is covered with a pit-shaped individual ink passage 28 having a height corresponding to the thickness of the partition wall 25 of 10 μm.
Are formed, and the common ink path 2 having a height of 10 μm connects the individual ink path 28 and the ink supply path 23 described above.
9 are formed.

A metal film 31 is formed on the upper surface of the orifice plate 14, and a nozzle hole (orifice) 32 for discharging ink is formed in a portion corresponding to the heating element 22 by dry etching. In this manner, a single head 12 having one row of nozzle holes 32 is formed, and four of them are connected in series to form a full-color nozzle shown in FIG.
A thermal inkjet head (color head) 10 is completed on a silicon wafer 15 (see FIG. 1B).

The mask metal film is made of Ni, C
By using u, Al, or the like, a selectivity of approximately 100 between the resin and the metal film can be obtained. Therefore, 20 to 40 μ
1 μm for dry etching of polyimide film
It is sufficient to form a mask with the following metal film.

As described above, it is possible to monolithically configure the color head 10 composed of four rows of single heads according to the above-described manufacturing method, and the positional relationship of each row is also determined by today's semiconductor manufacturing technology. It is possible to place them accurately.

The processing up to this point is performed in the state of a wafer.
Finally, as a step 7, a cutting is performed along a scribe line using a dicing saw or the like, divided into individual units, die-bonded to a mounting board, connected to terminals, and used as a practical unit of a color head. 10 is completed.

In the color head 10, when printing, each heating element 22 is selectively energized in accordance with print information.
Instantaneous heat generation causes a film boiling phenomenon, and the heating element 2
Ink droplets are ejected from the nozzle holes 32 corresponding to No. 2.
In such a thermal inkjet head, ink droplets are ejected in a substantially spherical shape having a size corresponding to the diameter of the nozzle hole,
It is printed on paper with a diameter approximately twice as large.

In the meantime, the basic manufacturing method has been described in the manufacturing process of the color head 10 described above. However, as a feature of the present embodiment, in addition to the above-described basic manufacturing method, the heating element 22 is formed. Special ingenuity is elaborated. By this measure, air bubbles are generated with high energy efficiency, and a heating element having strong resistance to cavitation damage and electrolytic corrosion is obtained.
Hereinafter, this will be described.

FIG. 3 shows a heating element 2 formed in step 2 of manufacturing the color head 10 according to the present embodiment.
It is a figure which shows the shape of No. 2 typically. It should be noted that FIG.
2 (a), (b) and (c), the same parts as those shown in FIGS. 2 (a), (b) and (c) ) and (c).

In the manufacturing of the thermal ink jet head (color head) according to the present embodiment, first, in the above-mentioned step 2, as shown in FIG. 3, a resistor made of Ta-Si-O having a thickness of about 7000 A body film is formed in a two-layer structure. Further, an electrode film is formed thereon, and the common electrode 1 is formed on the electrode film by photolithography.
8 and an electrode pattern of the individual wiring electrode 21 are formed, and a heating element pattern of the heating section 22 of 40 μm × 40 μm is formed on the resistor film having the two-layer structure.

The Ta-S layer under the two-layered resistor film is used.
i-O layer 22a (first Ta-Si-O layer) and upper T
In the a-Si-O layer 22b (second Ta-Si-O layer), the upper Ta-Si-O layer 22b is lower than the lower Ta-Si-O layer 22b.
The ratio of Si is smaller than that of the Si—O layer 22a. That is, when the molar ratio of Ta to Si is expressed as Ta / Si (the same applies hereinafter), “Ta / Si in the upper layer”> “Ta / Si in the lower layer”.

The following method is used to form this structure. That is, the lower first layer 22a uses a target in which a predetermined amount of Si is embedded in a Ta plate (for example, a molar ratio of Ta: Si =
3: 1) After the inside of the vacuum layer was evacuated to 1 × 10 ⁻⁶ Torr or less, a predetermined amount of argon gas was introduced, and the substrate temperature was reduced to 15 × 10 ⁻⁶ Torr.
After the film is formed at a temperature of 0 ° C. to 400 ° C., preferably about 200 ° C., and at a film forming rate of 15 ° / min to 40 ° / min, preferably about 20 ° / min, the film is formed more slowly than usual to a thickness of about 3600 °. The second layer 22b is formed on the first layer 22a by another target (for example, T
a: Si = 9: 1), a film having a smaller ratio of Si than the film of the first layer 22a is formed to a thickness of about 3400 ° continuously under the same conditions as the first layer 22a. Is formed.
In this step, the composition of the obtained Ta—Si—O film can be changed by changing the sputtering power. Thereafter, a wiring pattern is formed.

As described above, the lower layer 22b is used as the upper layer 22b.
A film in which the ratio of Si is smaller than that of a and the ratio of Ta is larger is formed, and then annealing (heat treatment) is performed at 400 ° C. for 10 minutes to thermally oxidize the film. Due to this thermal oxidation, the self-oxidation protection layer 22b-1 of the TaSiO film
It is formed with a thickness of not less than 00 ° and not more than 500 °. In the above annealing step, since the composition ratio of Ta of the upper layer 22b is large, even if the annealing temperature is about 200 ° C., the time is 1 hour.
If it takes 0 minutes or more, a sufficiently thick oxide film can be obtained.

Generally, an oxide film of Ta—Si—O is formed as shown in FIG.
As shown in FIG. 1, even though the thin film is thin, it shows strong resistance to cavitation damage and electrolytic corrosion, but remains unsatisfactory in terms of reliability as a thermal ink jet head.

However, when the thickness is 100 mm or more as described above, it can be said that the resistance to cavitation damage and electrolytic corrosion is sufficient even in consideration of the reliability as a thermal ink jet head. The lower layer and the second layer are formed of Si
Are different from each other only in the content ratio of Ta-Si.
Since it is an -O layer, it has excellent adhesion, and is almost integrated after film formation. In this respect, the heat generating portion 22 can maintain a favorable state in terms of thermal efficiency and the like.

In this case, since the portion of the upper layer other than the self-oxidized film has a high Ta content, the resistivity is small and sufficient heat cannot be obtained by itself, but in the present invention, the lower layer has a large resistivity. Since the Ta-Si-O layer is provided, sufficient heat generation can be obtained from the entire heating resistance film.

FIGS. 4 (a) and 4 (b) show the state of the surface by X-ray photoelectron spectroscopy (ESCA) in order to examine the change in the chemical bonding state before and after the heat treatment (annealing) of the Ta-Si-O film. It is a figure showing the result of measurement. Heat treatment at 400 ° C 10
Minutes. FIG. 9A shows measurement data before the heat treatment. The horizontal axis indicates the binding energy from “34” to “20”, and the vertical axis indicates the measurement count value from “0” to “1000”.
"0". FIG. 9B shows the measurement data after the heat treatment. The horizontal axis indicates the binding energy from “34” to “20” in the same manner as described above, and the vertical axis indicates the measurement count value from “0” to “14000”. To the top.

As shown in FIG. 2A, before the heat treatment, T
A 4f peak of a alone and a 4f peak showing the same bond as Ta ₂ O ₅ are observed. Then, as shown in FIG. 2B, after the heat treatment, the 4f peak of Ta alone disappears, and
The intensity of the 4f peak indicating the ₂ O ₅ -like bond was 4% before heat treatment.
It was confirmed that the peak was stronger than the f peak (shown by a thick solid line in FIG. 4B).

FIGS. 5 (a) and 5 (b) also show Ta-Si
FIG. 9 is a diagram showing a result of measuring a surface state by X-ray photoelectron spectroscopy (ESCA) in order to examine a change in a chemical bonding state before and after a heat treatment of an —O film. FIG. 5A shows measurement data before the heat treatment, and the horizontal axis represents the binding energy of “1”.
10 to 94, and the vertical axis indicates the measurement count value from 0 to above 5000. FIG. 9B shows the measurement data after the heat treatment. The horizontal axis indicates the binding energy from “110” to “9” in the same manner as described above.
4 ”, and the vertical axis indicates the measurement count value from“ 0 ”to“ 6000 ”.

As shown in FIG. 7A, before heat treatment, S
The signal from the 2P orbit of i is Ta-Si and TaSiOx
And SiOx. And the same figure
As shown in (b), after the heat treatment, a bond equivalent to that of an oxide film having good insulating properties such as SiO ₂ was not formed at the peak of Si, and it was confirmed that the Si peak did not change much.

From the above, the oxidation in the Ta—Si—O film is
It is considered that the reaction proceeds mainly around the Ta atom. For this reason, if a film rich in Ta is formed, thermal oxidation is expected to proceed more. Therefore, a film-forming experiment in which the ratio of Si / Ta was changed was performed.

FIG. 6 shows that the composition of Ta—Si—O is different.
4 is a table showing the resistivity (mΩcm) before and after annealing with different types of samples (Ta-Si-O films). The figure shows the sample numbers, the compositions of the samples of these sample numbers before annealing (the ratio of Ta, Si, and O, mol%), the resistivity before annealing and the resistivity after annealing (mΩcm), and the film forming apparatus. ID, analysis method, and Si / Ta molar ratio are shown.

The formation of the films of Sample Nos. 1 and 2
A C sputtering device was used. This device is shown in Table A
It is written. A target in which a predetermined amount of Si was embedded in a Ta plate was used as a target. 1 × 10 in vacuum layer
After evacuation to ^-6 Torr or less, a predetermined amount of argon gas was introduced, and splattering was performed. The substrate temperature is about 200 ° C., and the film formation rate is about 20 ° / min. The composition was changed by changing the sputtering power.

The films shown in Sample Nos. 3, 4 and 5 were formed using a DC magnetron buttering apparatus. This device is denoted by B in the table. The target used was a Ta plate on which a predetermined amount of Si chips had been placed. The substrate temperature changes, and the deposition rate is about 100 ° / m.
in. The composition was changed by changing the ratio of Si in the target.

After the annealing treatment after the film formation, the thickness of the oxide film of each of the sample Nos. 1 and 2 was about 50 °, and was a surface oxide film having a thickness equivalent to that of the conventional one. In addition, it was possible to measure the sheet resistance of the four-probe method even after annealing, and it was found from this point that a good oxide film was not formed.

The sample of sample number 3 is a target of Ta alone. Ta is crystallized, which is different from other films targeting TaSi. It is considered that the TaSiO film shows good resistance to cavitation damage due to amorphous, and thus the sample of sample number 3 is excluded. All samples other than this sample were amorphous before and after annealing.

The films of Sample Nos. 4 and 5 could not be measured for the sheet resistance by the four-probe method even after annealing, and it was found that the films were excellent oxide films. FIG. 7 is a diagram showing an analysis result in the depth direction of Auger photoelectron spectroscopy of the sample of sample number 4 described above. In this figure, the horizontal axis represents the sputtering time in minutes, and the vertical axis represents the concentration of the film composition. From the figure, it is clear that an oxide film having a thickness of about 200 ° is formed. Further, experiments have shown that the film thickness can be increased by increasing the proportion of Ta.

[0065]

As described above in detail, according to the present invention, a heating resistor film made of Ta-Si-O for forming a heating portion has a lower layer and a lower composition ratio of Si than the lower layer. Due to the two-layer structure of the upper layer, an oxide film formed on the upper Ta-Si-O film by heat treatment can be formed to a thickness of 100 mm or more, and therefore, a heating resistor having strong resistance to cavitation damage and electrolytic corrosion. A highly reliable thermal inkjet head having a film can be produced.

[Brief description of the drawings]

FIG. 1A is a diagram showing a full-color thermal inkjet head according to an embodiment, and FIG. 1B is a diagram showing a state in which a number of substrates (chips) are formed on a silicon wafer.

2A is a plan view and a sectional view showing a first step of manufacturing a thermal inkjet head, FIG. 2B is a plan view and a sectional view showing a next step, and FIG. 2C is a plan view showing a last step. FIG.

FIG. 3 is a diagram schematically illustrating a shape of a heating element formed in the thermal inkjet head according to the embodiment.

FIGS. 4A and 4B are diagrams (part 1) showing the results of measuring the change in the chemical bonding state of a Ta—Si—O film before and after heat treatment by X-ray photoelectron spectroscopy (ESCA).

5 (a) and 5 (b) are diagrams (part 2) showing the results of measuring the change in the chemical bonding state of the Ta-Si-O film before and after the heat treatment by X-ray photoelectron spectroscopy (ESCA).

FIG. 6 is a table showing the resistivity (mΩcm) before and after annealing of five types of samples (Ta-Si—O films) having different compositions of Ta—Si—O.

FIG. 7 is a diagram showing a result of Auger photoelectron spectroscopy analysis of a sample of sample No. 4 in a depth direction.

FIGS. 8A, 8B, and 8C are views showing a configuration in which ejection is performed in a direction parallel to a heating surface of a heating element of an ink jet head, and FIGS.
(e), (f) is a figure which shows the thing of a structure which discharges in the direction perpendicular | vertical to the heating surface of a heating element.

FIGS. 9A and 9B are diagrams schematically showing the process of growth and disappearance of cavitation bubbles related to ejection of ink droplets.

FIG. 10 is a diagram schematically showing a thin oxide film layer of a conventional heating element.

[Explanation of symbols]

Reference Signs List 1 silicon substrate 2 heating element (heating element) 2a Ta-Si-O layer 2b self-oxidized film 3 orifice plate 4 orifice 5 ink 5 'extruded ink 6 film bubble 7 ink droplet 8 open pool 9a common electrode 9b individual wiring electrode Reference Signs List 10 Thermal inkjet head 11 according to one embodiment 11 Substrate (chip) 12 (12a, 12b, 12c, 12d) Monocolor head 13 Nozzle row 14 Orifice plate 15 Silicon wafer 16 Drive circuit 17 Terminal 18 (18a, 18b) Common electrode 19 Common electrode power supply terminal 21 Individual wiring electrode 22 Heating element 23 Ink supply path 24 Ink supply hole 25 (25, 25-1, 25-2) Partition 26 Thermoplastic polyimide 28 Individual ink path 29 Common ink path 31 Metal film 32 Nozzle Hole (orifice)

Claims (8)

[Claims] 1. A heating resistor of a thermal inkjet head, which is provided on a substrate and generates air bubbles at an interface with supplied ink by generating heat to discharge ink droplets from a corresponding nozzle hole. And a first Ta-Si-O layer laminated on the first Ta-Si-O layer.
Si / Ta smaller than the Si / Ta molar ratio of the Si—O layer
A heat generating resistor comprising: a second Ta-Si-O layer having a molar ratio; and an oxide layer formed on the second Ta-Si-O layer. 2. The composition according to claim 1, wherein the first Ta—Si—O layer has a composition wherein the molar ratio of Si to Ta, Si / Ta, is “0.47 <S
2. The heating resistor according to claim 1, wherein i / Ta <0.75 and "25 mol% ≤O≤40 mol%". 3. The composition according to claim 2, wherein the second Ta—Si—O layer has a composition wherein the molar ratio of Si to Ta, Si / Ta, is “0 <Si / T”.
3. The structure according to claim 1, wherein a ≦ 0.15.
The heating resistor as described. 4. The oxide layer has a thickness of 100-500.
The heating resistor according to claim 1, 2 or 3, wherein Å. 5. A method for manufacturing a heating resistor of a thermal inkjet head, comprising: using a first target having a predetermined amount of Si embedded in a Ta plate, forming a first Ta-Si-O layer on a substrate. A first sputtering step of forming a first target and a second target in which a smaller percentage of Si than the first target is embedded in a Ta plate on the first Ta—Si—O layer. Second on the Ta-Si-O layer
A second sputtering step of forming a Ta-Si-O layer, and an annealing step of forming a thermal oxide film in a region serving as a heat generating portion on the second Ta-Si-O layer. Manufacturing method of resistor. 6. The Si / Ta mole ratio of the first target is 1/3, and the Si / Ta mole ratio of the second target is 1/3.
The method according to claim 5, wherein the molar ratio is 1/9. 7. The first and second sputtering steps both have a degree of vacuum of 1 × 10 ⁻⁶ Torr or less, a substrate temperature of 150 ° C. to 400 ° C., and a film forming rate of 15 ° / min.
7. The method according to claim 5, wherein the heating is performed at 40 [deg.] / Min in an argon gas atmosphere. 8. The manufacturing of a heating resistor according to claim 5, wherein the annealing step is a heat treatment at 400 ° C. for 10 minutes, and is performed after a wiring pattern is formed on the heating section. Method.