JPH07314684A - Substrate for recording head and its manufacture - Google Patents

Abstract

PURPOSE:To improve the ink discharge efficiency to the electric power to be consumed by a heating unit, by a method wherein in a sphere other than a heating part of an electricity heat conversion element is not provided with a cavitation-resistant layer and the other sphere is coated with insulation protective film comprised of at least two layers. CONSTITUTION:A part of a layer containing a wiring layer 108 is notched by a selective etching with a heating layer to form a heating part 140 and a heating resistive layer 107 is exposed. Then, a protective layer 1091 of the first layer is accumulated extending over the whole surface, a tantalum film is accumulated extending over the whole surface as a cavitation-resistant layer 112 against ink foaming and as for the caviation-resistant layer 112, only a heating part is left behind and the other sphere is removed. Then, the second protective layer 1092 is accumulated extending over the whole surface, a pattern to open not only the heating part 140 but also a pad part 111 is formed and not only the second protective layer 1092 in the heating part 140 but also the first and second protective layers 1091 and 1092 in the pad part 111 are removed by etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an ink jet recording apparatus in which a plurality of electrothermal converting elements and a plurality of driving functional elements are formed on the same substrate and ink is ejected by thermal energy for recording. The present invention relates to a novel recording head substrate and a method for manufacturing the same.

[0002]

2. Description of the Related Art The present invention forms a flying droplet by utilizing thermal energy, especially in an ink jet recording system,
The present invention provides an excellent effect in an inkjet type recording head and a recording device that perform recording.

Regarding its typical structure and principle, for example, the specifications of US Pat. Nos. 4,723,129 and 4740 are set forth.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal converter arranged corresponding to the sheet or liquid path in which is stored, which corresponds to the recorded information and causes a rapid temperature rise exceeding nucleate boiling. , It is effective because it generates heat energy in the electrothermal converter and causes film boiling on the heat-acting surface of the recording head, resulting in the formation of bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis. Is. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved.

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

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. The present invention also includes configurations using US Pat. No. 4,558,333 and US 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 structure in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and a pressure wave of thermal energy is absorbed. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a configuration in which an opening corresponds to a discharge portion.

Further, as a full line type recording head having a length corresponding to the width of the maximum recording medium which can be recorded by the recording apparatus, a combination of a plurality of recording heads as disclosed in the above-mentioned specification provides the length. The present invention can exert the above-mentioned effects more effectively, although it may have a configuration that satisfies the above requirement or a configuration as one recording head integrally formed.

In addition, by being mounted on the apparatus main body, it can be electrically connected to the apparatus main body and can be supplied with ink from the apparatus main body by a replaceable chip type recording head or the recording head itself. The present invention is also effective when a cartridge-type recording head provided with an ink tank is used.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. If you list these specifically,
Capping means, cleaning means, pressurizing or sucking means for the recording head, preheating means using an electrothermal converter or another heating element or a combination thereof, and a preliminary ejection mode for performing ejection other than recording It is also effective to perform stable recording.

Further, as the recording mode of the recording apparatus, not only the mainstream color such as black is recorded but also the recording head may be integrally formed or a plurality of them may be combined. The present invention is also extremely effective for a device provided with at least one of full colors by color mixing.

In the embodiments of the present invention described above, the ink is described as a liquid, but it is an ink that solidifies at room temperature or below and that softens at room temperature, or is a liquid, or the above-mentioned. In the inkjet method, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. It may be in a liquid form.

[0012] In addition, the temperature rise due to the thermal energy is positively prevented by using it as the energy for changing the state of the ink from the solid state to the liquid state, or the ink is solidified in the left state for the purpose of preventing evaporation of the ink. In some cases, such as ink that is liquefied by applying heat energy according to a recording signal and ejected as a liquid ink, or one that has already started to solidify when it reaches a recording medium. The use of an ink having a property of being liquefied only by heat energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or JP-A-60-71260, a mode in which the porous sheet is opposed to the electrothermal converter in the state of being held as a liquid or solid in the recess or through hole of the porous sheet. May be 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 the one provided integrally or separately as an image output terminal of information processing equipment such as a word processor or a computer, a copying apparatus combined with a reader or the like, May take the form of a facsimile machine having a transmission / reception function.

Conventionally, an ink jet recording apparatus having a recording head in which a plurality of electrothermal converting elements and a plurality of driving functional elements are provided on the same substrate is disclosed in, for example, JP-A-57-728.
No. 67 is proposed.

FIG. 9 is a sectional view showing a part of the recording head substrate having such a structure.

Reference numeral 101 denotes a semiconductor substrate made of single crystal silicon. A diode constituted by a bipolar transistor 120 as a driving functional element and a heat generating portion 140 are formed above the diode through an interlayer insulating layer 106.

Reference numeral 102 denotes an N-type semiconductor epitaxial layer,
103 is an N-type semiconductor ohmic region having a high impurity concentration, 1
Reference numeral 04 is a P-type semiconductor base region, and 105 is a high-impurity-concentration N-type semiconductor emitter region, which form a bipolar transistor. The base region 104 and the N-type semiconductor ohmic region 103 that is a collector region are common. It operates as a diode by being connected by the electrodes.

Reference numeral 100 is a P-type isolation region for element isolation. The heat storage layer 121 and the interlayer insulating layer 106 are silicon oxide layers, and 122 is an aluminum connection electrode from the isolation region 100 and each part of the transistor.

A heating portion is formed on the upper layer of these regions. First, there is a heating resistance layer 107, a wiring layer 108 made of aluminum or aluminum alloy is further formed, and a silicon oxide or silicon nitride film which is a protective layer 109 formed by plasma CVD or the like is further formed thereon.
Reference numeral 112 is a tantalum layer that acts as a protective layer, and has the purpose of mainly functioning as a cavitation-resistant layer that prevents mechanical wear of the contact surface due to cavitation during ink foaming and defoaming. Reference numeral 111 is a pad opening for making an electrical connection with the recording apparatus.

A main body 1 for a recording head having the above as a main part
30 is configured, and a top plate and a liquid path for introducing and further ejecting ink are formed on the base 130 to configure a recording head.

The recording head of the ink jet recording apparatus is, that is, a specific heating resistance layer 107 selected from a plurality of heating resistance layers 107 is energized by the operation of the diode element by the bipolar transistor 120 according to a control signal from the outside, The ink arranged immediately above the heat generating portion 140 is rapidly heated and foamed, and the ink is ejected onto the recording surface to form a recorded image. Each of the functional elements is a component forming the heart of a recording head in which a plurality of functional elements are precisely formed.

[0022]

In recent years, there have been great demands for downsizing, high-speed operation, energy saving, and cost reduction of such a recording apparatus, and conventional recording head substrates meet these problems. It was not possible to exert sufficient performance.

In particular, for the heat generating section 140, there has been a strong demand for improving the efficiency of ink ejection with respect to the electric power consumed by the heat generating element, as described below, due to its configuration.

That is, in the heat generating section 140,
As described with reference to FIG. 9, the heat storage layer and the interlayer insulating layer are used.
All SiO₂ HfB on layer 106₂ Heat generating resistance layer 10
7 is formed to a thickness of about 1000Å, and on top of this
Aluminum wiring 108 is about 500 to reduce wiring resistance
It is formed with a thickness of 0Å. Therefore the SiO above it ₂ 
The protective layer 109 has a step of at least 5000 Å or more.
Even if there is a difference, it must be covered well,
In order to secure the property, a protective layer thickness of 5000 Å or more is required.
It was. Aluminum wiring, especially for the purpose of cost reduction
When patterning by wet etching,
High purity aluminum is used as the wire material, and P-CV
In the thermal process of forming the protective layer by method D, aluminum
Growth increases, and its height is several thousand Å ~ 1 μm or more
There can be growth of hillocks and whiskers. Therefore trust
In order to secure the property, the protective layer should be at least 10000Å
Was needed. Furthermore, tantalum is on the protective layer 109.
The cavitation resistant layer 112 such as
It is formed with 0Å thickness. Therefore, the heating resistance layer 107
The heat generated in the storage is less than 10,000 Å, which has low thermal conductivity.
Ink is transferred through the protective layer 109 and the tantalum film 112 of several thousand liters.
Therefore, it cannot be said that the heat transfer efficiency is good because
Power consumption in the heating resistor layer 107 due to heat diffusion in the middle path
Ink ejection efficiency is lower than that of
There are obstacles to speeding up and miniaturization of equipment such as heat diffusion to adjacent nozzles.
Was becoming.

[0025]

In the present invention, the structure of the protective layer 109 in the prior art is divided into a plurality of layers, and the cavitation-resistant layer is arranged only in the heat generating portion, so that the uppermost protection layer is formed. The layer is not provided on the cavitation resistant layer. With this configuration, it is possible to provide a recording head substrate with high ink ejection efficiency while ensuring high reliability and high yield even if the protective film thickness of the heat generating portion is set to several thousand Å.

[0026]

1 is a sectional view of a recording head substrate according to an embodiment of the present invention. The layer structure below the heat generating portion 140 is formed on the silicon substrate 101 in the same manner as in the prior art by forming the epitaxial layer 102, the isolation region 100, and the driving functional element by the bipolar transistor 120. In the following description, the detailed structure in the driving functional element as shown in FIG. 9 of the conventional example is not directly related to the purpose of the present invention, and therefore the description is omitted.

The features of the present invention are the structure of the heat generating portion 140, the first protective layer 1091 and the second protective layer 1092 which cover the heat generating portion and the driving functional element (bipolar transistor in this example), and the anti-cavitation layer 112. Is located.

The steps of manufacturing the recording head substrate of the present invention will be described below in order with reference to FIGS.

Referring to FIG. A plurality of bipolar transistors 120 and isolation regions 100 are formed on a silicon substrate 101 and an epitaxial layer 102, and an aluminum or aluminum alloy connection electrode 122 is formed from each isolation region and the emitter, base, and collector regions of the transistors. I am doing it. The epitaxial layer 102 and the driving element portion 120 are covered with a thermal oxide film 121 of silicon, and the connection electrode 122
Is formed by opening the thermal oxide film 121 at each connection portion.
Since the thermal oxide film 121 also functions as a heat storage layer for enhancing the heat utilization efficiency below the heat generating portion, it is preferably formed thicker than the driving element portion, for example, 1 to 1.5 μm.
It is suitable for the purpose of the present invention. After that, the interlayer insulating layer 106 is formed with a silicon oxide film to a thickness of about 1 μm by plasma CVD or the like. Then, a part of the interlayer insulating layer 106 is opened to connect to the first-layer aluminum connection electrode 122, and a through hole is formed.

Next, the heating resistance layer 107 and the wiring layer 108 made of aluminum or aluminum alloy are first deposited on the entire surface by sputtering or the like, and then a resist is applied by patterning on the wiring layer including the portion to be the wiring layer by photolithography. After that, the wiring layer and the heat generating resistance layer are left, and dry etching is performed to obtain a shape including a predetermined wiring layer 108. Next, in order to form the heat generating portion 140, the wiring layer 1
A part of the layer having the shape obtained above including 08 is cut out by selective etching with the heat generating layer to expose the heat generating resistance layer 107.

Materials for forming the heating resistance layer include HfB ₂ , ZrB ₂ , Ta, TaN, Ta-Al, and T.
There are materials such as a-Si, Ta-Mo, W, Ta-W, and Ni-Cr. For example, if HfB ₂ or TaN is used, it can be formed with a thickness of about 0.1 μm and a sheet resistance of about 20 Ω / □.

The wiring layer 108 can be selectively etched with a heating resistance layer such as TaN by forming the wiring layer 108 to a thickness of about 0.5 μm if aluminum is used and performing wet etching with an alkaline solution.

Next, referring to FIG. 3, the first protective layer 109 is formed.
1 will be described from the point where a silicon nitride film is deposited and formed on the entire surface by plasma CVD.

Subsequently, a tantalum film is deposited on the entire surface as a cavitation resistant layer 112 against ink foaming by sputtering.

Here, the thickness of the first protective layer 1091 is, for example, about 0.2 to 0.4 μm, and in the heat generating portion, the heat generating resistance layer 107 exposed from below and the tantalum film serving as the upper layer are in the heat generating portion. In the case of forming a thin film so that a short circuit does not occur, the effect which is not intended for the purpose of the present invention becomes larger as described later.

The tantalum film formed on this is an anti-cavitation layer, and its function is about 0.1 to 0.2 μm.
It is formed to a thickness of m.

Next, referring to FIG. 4, the anti-cavitation layer 112 is removed by photolithography and etching, leaving only the heat generating portion and other regions.

Next, referring to FIG. 5, the second protective layer 10
A process of depositing a silicon nitride film to be 92 on the entire surface by plasma CVD will be described. This layer is formed to have a thickness of 0.5 to 1 [mu] m for the purpose of sufficiently covering the steps generated by the formation of the wiring layer 108, the anti-cavitation layer 112 and the like and ensuring the insulation.

Finally, a pattern for opening the heat generating portion 140 and the pad portion 111 is formed by photolithography, and in the heat generating portion 140, the second protective layer 109 is formed.
2. In the pad portion (111), the first and second protective layers (1091, 1092) are removed by etching. For this purpose, for example, RIE (Riactive Ion Etchin
g) CHF ₃ 30S as an etching gas by using the device
Introduce CCM and O ₂ 15 SCCM, gas pressure 10P
a, if the etching is performed with an RF power of 800 W, the ratio of the etching rate of plasma silicon nitride to the etching rate of tantalum, that is, the so-called selection ratio can be set to about 20. 2 silicon nitride protective layer 1
A portion of 092 can be removed as desired.

As described above, in the recording head substrate of the present invention, the arrangement of each layer in the main part is configured as described above. Therefore, in the heating portion, the protective coating on the heating resistance layer 107 is the first protective layer. 1091 and anti-cavitation layer 1
The total thickness of 12 is 0.3 to 0.6 μm, which is reduced to 1/4 to 1/2 of the conventional thickness of 1.1 to 1.2 μm. The first protective layer 1091 and the second protective layer 1092 on the first protective layer 1091 are sufficiently covered with a thickness of 0.5 to 1.0 μm, and the steps of the wiring layers are also sufficiently covered. Furthermore, if at least one of these two protective layers is made of a silicon nitride film, it is also excellent in the blocking property of sodium ions, so that the protective film can have ink resistance. Further, by forming the protective film with at least two layers, the possibility of through-holes occurring in the protective film due to pinholes generated during the manufacturing process is reduced, which contributes to improvement in product yield.

Further, in the heat generating portion where the wear of the element due to cavitation is the most severe, since it is covered with the tantalum film as in the conventional case, the element life due to the ink ejection does not have an effect that is inferior to the conventional case, but rather as described later. Ejection efficiency is improved as a result of improved thermal efficiency, and thus the applied power is reduced, so that the life tends to be longer.

Further, by using the cavitation resistant layer 112 as an etch stop layer for the upper protective layer, the protective coating of the heat generating portion can be controlled to a constant thickness, and variations in element characteristics can be suppressed. . Compared with the prior art, the number of steps of forming the protective film is increased once, but the number of steps of pattern formation by photolithography and etching is not increased, and the effect on cost increase is slight.

According to the constitution of the present invention, the protective layer 1 for the heat generating portion is formed.
091 is 3000 Å, and the cavitation resistant layer 112 is
The recording head with 2000 Å has a conventional protective layer 109
Is 10,000 Å and the anti-cavitation layer 112 is 200
Compared to the case of 0 Å, the power consumption for ink ejection could be reduced to about 60%.

Although the constitution of the present invention has been sufficiently clarified by the above description, the improvement of the present invention will be shown by showing an embodiment in which some modifications are combined.

In the embodiment of the present invention shown in FIG. 6, the anti-cavitation layer 1 is provided corresponding to each of the plurality of heat generating portions.
12 and the opening of the second protective layer 1092 are provided respectively. This is to secure the thickness of the protective film on the adjacent wiring layer for current circulation and improve reliability. In each heat generating portion, only the opening of the second protective layer or both the opening and the cavitation resistant layer may be formed inside the heat generating resistance layer exposed portion. in this case,
Since the step due to the heating resistance layer having a thickness of about 0.05 to 0.1 μm is covered by not only the thin first protective layer but also the thick second protective layer, the reliability can be further improved.

The present invention can also have a structure as shown in FIGS. 7 and 8. FIG. 7 is a sectional view in that case, and FIG. 8 is a plan view of the vicinity of the heat generating portion. In this example, the wiring layer 123 for current flow is formed below the heating resistance layer 107 and the wiring layer 108 with the interlayer insulating layer 106 interposed therebetween. By arranging in this way, the wiring space is reduced, so that it is possible to increase the integration degree of the heat generating portion.

In this example, since there is no wiring layer adjacent to the heat generating portion, the openings for the cavitation resistant layer 112 and the second protective layer 1092 that are common to the plurality of heat generating portions can be provided. As a result, it is not necessary to take a pattern alignment margin in the direction in which the heat generating portions are arranged, and there is a possibility that the degree of integration can be improved.

In the embodiment of the present invention described above,
Although the first and second protective layers are made of a silicon nitride film and the anticavitation layer is made of tantalum, it will be further explained that the same effect can be obtained with other material configurations.

For example, the first protective layer may be a SiO film formed by plasma CVD or atmospheric pressure CVD, PSG (phospho-silicate g).
The second protective layer may be a silicon nitride film formed by plasma CVD as a lass film or a SiON film.

Further, it is possible to use a Ta-N film formed by reactive sputtering or the like for the cavitation resistant layer. In this case, it is possible to remove the second protective film by wet etching using, for example, buffered hydrofluoric acid by utilizing that the Ta-N film is not easily etched by hydrofluoric acid.

[0051]

The recording head substrate of the present invention having the above-described structure brings about the following effects. (1) It is possible to secure a high reliability and a high yield, and yet to make the thickness of the protective layer of the heat generating portion as thin as several thousand Å. (2) It becomes possible to reduce the power consumption, for example, when the thickness of the protective layer including the cavitation-resistant layer on the heat generating portion is 5000Å, the power consumption can be reduced to about 60% as compared with the conventional one. (3) Although the film forming process is increased by one process as compared with the conventional one, the photolithography process and the etching process are not increased and the cost increase can be suppressed. (4) By improving the efficiency of power consumption related to ink ejection, power consumption is reduced and therefore the life of the substrate is extended.

[Brief description of drawings]

FIG. 1 is a sectional view of a recording head substrate of the present invention.

FIG. 2 is a diagram illustrating a process of manufacturing a recording head substrate of the present invention.

FIG. 3 is a diagram illustrating a process of manufacturing a recording head substrate of the present invention.

FIG. 4 is a diagram illustrating a process of manufacturing a recording head substrate of the present invention.

FIG. 5 is a diagram illustrating a process for manufacturing a recording head substrate of the present invention.

FIG. 6 is a plan view of the vicinity of a heat generating portion of the recording head substrate of the present invention.

FIG. 7 is a sectional view of another example of the recording head substrate of the present invention.

FIG. 8 is a plan view of the vicinity of a heat generating portion of another example of the recording head substrate of the present invention.

FIG. 9 is a sectional view of a conventional recording head substrate.

[Explanation of symbols]

 100 Isolation Region 101 Silicon Substrate 102 Epitaxial Layer 106 Interlayer Insulating Layer 107 Heating Resistance Layer 108 Wiring Layer 109 Protective Layer 1091 First Protective Layer 1092 Second Protective Layer 112 Cavitation Resistant Layer 120 Bipolar Transistor 121 Thermal Oxidation Film 140 Heat Generation Section

Claims (6)

[Claims] 1. In a substrate for an ink jet recording head in which a plurality of electrothermal conversion elements and a plurality of driving functional elements are formed on the same substrate, an upper layer is provided on a region other than a heat generating portion of the electrothermal conversion element. 2. A recording head substrate, characterized in that a conductive anti-cavitation layer is not formed in, and is covered with at least two layers of an insulating protective film on other regions. 2. The recording head substrate according to claim 1, wherein the anti-cavitation layer is made of tantalum, and at least one of the insulating protective layers is made of silicon nitride. 3. The recording head substrate according to claim 1, wherein the anti-cavitation layer is made of tantalum nitride, and at least one of the insulating protective layers is made of silicon nitride. 4. A method of manufacturing a recording head substrate in which a plurality of electrothermal conversion elements and a plurality of driving functional elements are formed on the same substrate, wherein (1) the first protective layer is an insulating protective film. Depositing on a substrate, (2) depositing a conductive anti-cavitation layer on the upper layer, (3) forming a pattern so as to leave the anti-cavitation layer on at least the heat generating region of the electrothermal conversion element, (4) A step of depositing a second insulating protective layer on the cavitation-resistant layer, and (5) at least the second insulating protective layer on the heating portion region is removed by etching using the cavitation-resistant layer as an etch stop layer. A method of manufacturing a recording head substrate. 5. The method of manufacturing a recording head substrate according to claim 4, wherein the anti-cavitation layer is made of tantalum and at least one of the first and second insulating protective layers is made of silicon nitride. . 6. The anti-cavitation layer is made of tantalum nitride, and at least one of the first and second insulating protective layers is made of silicon nitride.
A method for manufacturing a recording head substrate according to item 1.