JP2003136738A - Circuit board, liquid discharge head, and method for manufacturing these - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board having good step coverage efficiency by a protecting layer and a cavitation resistant film at a wiring edge part, and a liquid discharge head using the same. SOLUTION: A conductive film is patterned to form a conductive film pattern including electrodes. Then, an insulating material is piled onto an entire face and etched to eliminate an unnecessary part. A tilting ease part of the insulating material is formed between electrodes to make a surface shape between the pairing electrodes within a predetermined angle range. Thereafter, a resistance layer is formed on the conductive pattern and the tilting ease part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board provided with an element having a resistance layer, a liquid discharge head, and a method for manufacturing the same, and more particularly to a method for converting electric energy into heat energy and liquid by the heat energy. The present invention relates to a method of manufacturing a circuit board for a liquid ejection head that ejects liquid.

[0002]

2. Description of the Related Art Inkjet recording apparatuses record high-definition images by ejecting ink as minute droplets from a discharge port onto a recording member. At that time, the inkjet recording device converts electric energy into heat energy,
Bubbles are generated in the ink by heat energy. Droplets are ejected from the ejection port at the tip of the liquid ejection head by the action force of the bubbles. The liquid droplets ejected from the ejection port adhere to the recording member to record an image. In general, such a liquid ejection head has a circuit board provided with a plurality of elements each including a heating resistor that converts electric energy into heat energy.

The heating resistor is a heat converter that converts electric energy to generate heat energy. The heating resistor is protected by the upper protective layer so as not to come into contact with the ink.

FIG. 6 is a sectional view showing an example of a heating resistance element of a conventional circuit board for a liquid ejection head. Referring to FIG. 6, the circuit board is made of SiO 2 on a Si substrate (not shown).
_{There is a second} interlayer film 61, and a heating resistor film 62 of TaSiN is formed on the interlayer film 61. Although there is an Al wiring 63 on the heating resistor, there is a portion on the heating resistor film 62 where there is no wiring 63. The portion without the wiring 63 becomes the heat acting portion 64. A protective layer 65 is provided on the heat-generating resistor film 62 and the wiring 63 to protect them from the ink. In the heat acting portion 64, the protective layer 65 is protected from chemical or physical damage due to heat generation. A Ta anti-cavitation film 66 for protection is provided on the protection layer 65.
The wiring 63 is almost vertical.

The circuit board for the liquid discharge head has a plurality of heat generating resistance elements as described above at a high density and enables recording of high-definition images. Each heating resistance element is connected in series with a power transistor (not shown) that controls on / off of the current flowing through the heating resistance element.

FIG. 7 is an equivalent circuit of a circuit board focusing on one heating resistance element. Referring to FIG. 7, the resistance RA of the wiring 63 is provided between the heater voltage VH and the ground potential GND.
L, a resistance RH equivalent to a heating resistance element, and a power transistor TR are connected in series.

By reducing the resistance RAl of the wiring 63, it is possible to reduce the power consumption of the ink jet recording apparatus without lowering the thermal energy generated by the heating resistance element. In order to reduce the value of the resistance RAl, it is effective to increase the film thickness of the wiring 63.

Further, in order to reduce the reciprocating movement of the liquid discharge head and meet the demand for higher speed of the recording apparatus, in recent years, the length of the circuit board has been increased. When the circuit board becomes long, the wiring 63 inevitably becomes long. Since the value of the resistance RAl increases as the length of the wiring 63 becomes longer, it is effective to increase the thickness of the wiring 63 as a measure against this. Currently, the film thickness of the wiring 63 is about 200 nm to 600 nm,
It is considered to be about 1200 nm in the future.

As shown in FIG. 6, since the protective layer 65 and the cavitation resistant film 66 are hard to be formed in the vertical portion, the cavitation resistant film 65 and the protective layer 64 are separated from the ink by the boundary portion 68 with the edge portion 67. And the heating resistor film 62 is further eroded by the heat generation, and a partial cut is likely to occur.

In order to improve the step coverage of the heat acting portion 64 due to the protective layer 65 or the like, the protective layer 65 or the like may be thickened. However, since the protective layer 65 and the like serve as a thermal resistance when the thermal energy is transferred to the ink, if the protective layer 65 is thick, it is necessary to increase the driving power, and the frequency characteristic is deteriorated due to the heat conduction delay. . Therefore, lower power consumption and higher performance of the liquid ejection head are hindered.

As another circuit board of the liquid discharge head, there is a circuit board in which this point is improved.

FIG. 8 is a sectional view showing an example of another conventional heating resistor element on a circuit board. In FIG. 8, as in the case of FIG. 6, the heating resistor film 62 is provided on the interlayer film 61, and the wiring 8 is provided on the heating resistor film 62 in the portion other than the heat acting portion 82.
There is one. However, in FIG. 8, the edge portion 85 is not perpendicular to the film surface of the heating resistor film 62 but has a taper shape having a predetermined angle.

According to this circuit board, the step coverage of the heat acting portion 82 due to the protective layer 83 and the anticavitation film 84 is also improved. If the taper angle is set within an appropriate range, it becomes difficult for the heating resistor film 62 to be partially cut,
The durability of the liquid ejection head is improved.

An example of a method of forming a circuit board as shown in FIG. 8 is as follows. First, an Al material layer to be wiring is deposited on the heating resistor film 62, patterned by dry etching, and then a mask photoresist. (Positive resist containing novolac resin as a main component) is applied, the mask photoresist in the portion to be etched is removed, and the opening is opened. Then, the material layer is etched while retreating the mask photoresist with an alkaline solution containing tetra-methyl-ammonium-hydroxide (hereinafter referred to as TMAH) as a main component while retreating the mask photoresist.

Then, in the region where the mask photoresist has receded, the material layer becomes a slope having a predetermined angle, and the edge portion 85 of the wiring 81 is not vertical but tapered.
After that, after removing the mask photoresist, a protective layer or a cavitation resistant film may be formed.

As another method of forming a wiring having a tapered edge portion, there is a method of etching the Al material layer while removing the mask photoresist. In this method, the etching solution gradually enters under the mask photoresist to form a tapered shape.

[0017]

A method of forming the edge portion 95 of the wiring 91 in a taper shape while retreating or peeling the mask photoresist is to reduce the thickness of the wiring 91, that is, the thickness of the material layer. Up to about 600 nm,
This is an effective method capable of forming a good taper. However, it becomes difficult to form a proper taper as the material layer becomes thicker. Therefore, this method may not be able to cope with an increase in the film thickness of the wiring 91 in the future.

It is an object of the present invention to provide a circuit board having a good step coverage due to a protective layer or an anti-cavitation film at the edge portion of the wiring, and a liquid discharge head using the same.

[0019]

In order to achieve the above object, a method of manufacturing a circuit board according to the present invention is a method of manufacturing a circuit board in which an element having a pair of electrodes facing each other at a predetermined interval is formed. In order to form a conductive film pattern including the electrodes, and a second step of forming a slope relaxation portion of an insulating material between the paired electrodes. Characterize.

The second step may include a step of depositing the insulating material on the entire surface and a step of etching the insulating material to remove unnecessary portions.

[0021] It is preferable that the tilt relaxing portion is a pair of tilt relaxing walls having slopes descending from the respective electrodes toward the facing electrodes.

It is preferable that the method further includes a third step of forming a resistance layer on the conductive pattern and the slope relaxation portion.

The inclination relaxing portion has an inclined surface that descends from each of the electrodes in the direction of the opposing electrode, and the angle range of the inclined surface is 5
It is preferably 0 degrees or less.

The method of manufacturing a liquid discharge head according to the present invention is the method of manufacturing a liquid discharge head in which electric energy is converted into heat energy by a heating resistor and the heat energy is used to discharge a liquid. It is characterized by including a step of preparing a circuit board manufactured by the method for manufacturing a circuit board described above, and a step of forming a discharge port for discharging a liquid corresponding to the element of the circuit board.

Further, the circuit board of the present invention is a circuit board in which an element having a pair of electrodes facing each other at a predetermined interval is formed, and a tilt relaxing portion of an insulating material is formed between the pair of electrodes. It is characterized by being.

In the liquid discharge head of the present invention, the electric energy is converted into heat energy by the heat generating resistance element,
In the liquid ejection head for ejecting a liquid by using the thermal energy, an inclination relaxation part of an insulating material is formed between a pair of electrodes of the heating resistance element facing each other at a predetermined interval. And

Therefore, the circuit board manufactured by the method of the present invention has the step coverage of the protective layer and the cavitation resistant film due to the formation of the inclination relaxing portion.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION A method of manufacturing a circuit board according to the present invention comprises:
In the process of forming the heat acting portion, the step coverage of the protective layer and the cavitation resistant film of the heat acting portion is improved. This method is especially effective when the wiring has a large film thickness.

The step coverage is the degree of whether or not the protective layer or the like covers and protects the heating resistor film and the wiring with a sufficient thickness. If there is a portion with poor step coverage, it is necessary to deposit a thick protective layer as a whole in order to form a protective layer having a sufficient thickness, which deteriorates heat transfer efficiency and heat transfer rate. . If the step coverage is uniform and good as a whole, it is possible to manufacture a recording head having high heat transfer efficiency, low power consumption, high heat transfer speed and high-speed operation, and high durability.

One embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining a method of manufacturing a circuit board according to one embodiment of the present invention. A method of forming the heat generating resistance element characteristic of this aspect will be described.

First, on a Si substrate 11, for example, BP
SG (Boro-Phospho-Silicate-
An insulating layer 12 of glass) and a heat storage layer 13 of silicon oxide (P-SiO) formed by plasma CVD are deposited in this order, and wiring 14 of aluminum (Al-Cu) containing copper is formed (FIG. 1A). ). The wiring 14 is formed, for example, by depositing a conductive film of Al—Cu on the entire surface and then patterning it by dry etching or the like.
The edge portion 15 of the wiring 14 is substantially perpendicular to the film surface of the heat storage layer 13.

For example, the thickness of the insulating layer 12 is 700 nm, the thickness of the heat storage layer 13 is 1200 nm, and the wiring 1
The film thickness of 4 is 1200 nm.

FIG. 2 is a top view of the substrate in the state of FIG. In the part that becomes the heating resistance element, 2
The two wirings 14 face each other and are patterned so as to connect the heating resistance element to another element (not shown) or an electrode (not shown).

Next, P-Si is applied to the edge portion 15 of the wiring 14.
The inclined relaxation wall 16 of O is formed (FIG. 1 (B)). The edge portion 15 is provided with an inclination relaxing wall 16 having a shape that is inclined in the direction of the wiring 14 facing the edge portion 15. As a result, the surface shape between the wirings 14 facing each other becomes gentle. Figure 3
[FIG. 2] is a view of the substrate in the state of FIG.

Next, a heat generating resistor film 17 is deposited so as to cover the heat storage layer 13, the wiring 14 and the inclined relaxation wall 15 (FIG. 1C). The thickness of the heating resistor film 17 is, for example,
It is amorphous TaSiN of 30 nm to 80 nm.

Next, a protective layer 18 of silicon nitride (P-SiN) is deposited on the heating resistor film 17 by plasma CVD if necessary (FIG. 1 (D)). As an example, the thickness of the protective layer 18 is 300 nm to 800 nm.

Next, if necessary, a cavitation resistant layer 19 of Ta is deposited on the protective layer 18 by a sputtering method so as to cover the heat generating portion (FIG. 1 (E)). As an example, the thickness of the anti-cavitation layer is 230 nm.

FIG. 4 is a diagram for explaining a method of forming the inclined relaxation wall 16. Referring to FIG. 4, FIG.
A method of forming the inclined relaxation wall 16 of (B) will be described.

First, the wiring 14 formed on the heat storage layer 13
By plasma CVD so as to cover the edge portion 15 of
An as-deposited film 41 of —SiO is deposited (FIG. 4A).
The as-deposited film 41 of P-SiO has a thickness of
Should be sufficient to form As an example, the film thickness of the as-deposited film 41 is 300 nm while the film thickness of the wiring 14 is 1200 nm.

Next, the as-deposited film 41 in the other portions is removed (etched back) by anisotropic etching, leaving the portion covering the edge portion 15 to form the inclined relaxation wall 16 (FIG. 2).
(B)). The edge auxiliary wall 16 is left so that a slope from the upper surface of the wiring 14 to the upper surface of the heat storage layer 13 is formed. It is desirable that the slope has an angle of 50 degrees or less with respect to the film surface of the heat storage layer 13, but if the slope is formed even if it does not fall within this range, the step coverage is improved. For this etch back, for example, CF ₄ gas is used. The inclined surface does not necessarily have to be a flat surface, and may be a complex flat surface that is bent upward or downward, or may be a curved surface that is convex upward or downward.

In the circuit board on which the heating resistance element is formed as described above, the protective layer 18 and the anti-cavitation film 1 are formed because the inclined relaxation wall 16 is formed on the edge portion 15.
9 and the like may be deposited not on the vertical portion but on the slope, so that the step coverage is high, and it is difficult for the heating resistor film 17 to be partially cut due to the erosion by the ink. The head can be realized.

Here, an example is shown in which the inclination relaxing wall 16 having a shape that descends in the direction of the opposing wiring 14 is formed separately at the edge portion 15 of each wiring 14, but the present invention has this shape. It is not limited to.

FIG. 5 is a diagram for explaining a method of manufacturing a circuit board according to another aspect of the present invention. In FIG. 5, a P-SiO tilt relaxation portion 51 is formed instead of the tilt relaxation wall 16 in FIG. The inclination relaxing portion 51 is not separated between the opposing wirings 14 and is integrally formed.

The method of forming the inclination relaxing portion 51 of FIG.
It is similar to that shown in FIG. 2, and after depositing the as-deposited film of P-SiO by plasma CVD, unnecessary portions of the as-deposited film are removed by etching (etchback). At this time, some as-deposited film should be left. Good.

In the case of FIG. 5, the inclination relaxing portion 5 is provided on the edge portion 15.
Since the protective layer 18 and the cavitation-resistant film 19 are formed on the slope instead of on the vertical portion, the step coverage is high and the heating resistor is eroded by the ink. It is possible to realize a recording head with high durability in which part of the film 17 is unlikely to be cut.

This means that in FIG.
6 is formed, the as-deposited film 4 between the wirings 14 facing each other is formed.
It also means that it is not necessary to completely remove 1 by etching back.

The film thickness of each layer used here is an example, and the present invention is not limited thereto. In particular,
The present invention is effective when the film thickness of the wiring 17 is thick.
You may use it in the case of 00 nm or less.

Although the heating resistor film 17 is formed on the wiring 14 here, the heating resistor film 17 may be formed under the wiring 14.

An example of the method of manufacturing the inkjet recording head substrate of this embodiment will be described. The production of the inkjet recording head substrate of this embodiment is carried out by well-known steps except the formation of the heat acting portion which is the feature of the present invention.

First, a silicon oxide film is formed on a P-type silicon substrate, N-type impurity ion implantation and thermal diffusion,
By removing the silicon oxide film by photolithography or the like, a transistor which is a driving element for driving the ink jet recording head and various Al electrodes connected to the transistor are formed. In this state, various electrodes are exposed on the upper part.

Next, the insulating layer 12 and the heat storage layer 13 are formed by the sputtering method or the CVD method. And
The insulating layer 12 and the heat storage layer 13 on the electrodes that require electrical connection are removed by photolithography to form through holes. Next, a material layer of Al is deposited on the electrodes having the through holes and the heat storage layer 13 and patterned to form the wiring 14.

Next, the P-SiO as-deposited film 21 is deposited and then etched back to form the edge auxiliary wall 16. Next, the heating resistor film 17, the protective layer 18, and the cavitation resistant film 19 are deposited in this order, and if necessary, each film is partially removed to form a pad for bonding. The base is completed.

A liquid discharge head can be manufactured by forming discharge ports on the circuit board thus obtained. Specifically, a nozzle wall, a top plate, or the like may be provided on the circuit board to form an ejection unit including an ejection port and an ink flow path.

[0055]

The circuit board manufactured by the method of the present invention has the step relaxation property of the protective layer and the cavitation resistant film due to the formation of the inclination relaxing portion, and the liquid discharge head using the circuit board is It has excellent durability.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method for manufacturing a circuit board according to one embodiment of the present invention.

FIG. 2 is a diagram of the substrate in the state of FIG. 1A as viewed from above.

FIG. 3 is a diagram of the substrate in the state of FIG. 1B as viewed from above.

FIG. 4 is a diagram for explaining a method of forming an inclined relaxation wall.

FIG. 5 is a diagram illustrating a method for manufacturing a circuit board according to another aspect of the present invention.

FIG. 6 is a cross-sectional view showing an example of a heating resistance element of a conventional circuit board for a liquid ejection head.

FIG. 7 is an equivalent circuit of the circuit board focusing on one heating resistance element.

FIG. 8 is a cross-sectional view showing an example of a conventional heating resistor element on another circuit board.

[Explanation of symbols]

11 board 12 Insulation layer 13 Heat storage layer 14 wiring 15 Edge 16 Inclined wall 17 Heating resistor film 18 Protective layer 19 Anti-cavitation film 41 As Depot Membrane 51 Inclination relaxation section

Continued front page    (72) Inventor Genzo Monma             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2C057 AF65 AF93 AF99 AG83 AG91                       AP32 AP34 AP53 AQ02 BA03                       BA13

Claims (8)

[Claims] 1. A method for manufacturing a circuit board, wherein an element having a pair of electrodes facing each other with a predetermined interval is formed, wherein a conductive film is patterned to form a conductive film pattern including the electrodes. A method of manufacturing a circuit board, comprising: a step; and a second step of forming a slope relaxation portion of an insulating material between the pair of electrodes. 2. The circuit board according to claim 1, wherein the second step includes a step of depositing the insulating material on the entire surface and a step of etching the insulating material to remove unnecessary portions. Production method. 3. The method for manufacturing a circuit board according to claim 1, wherein the tilt relaxing portion is a pair of tilt relaxing walls having slopes that descend from the respective electrodes toward the facing electrodes. 4. The method of manufacturing a circuit board according to claim 1, further comprising a third step of forming a resistance layer on the conductive pattern and the inclination relaxing portion. 5. The method for manufacturing a circuit board according to claim 1, wherein the inclination relaxing portion has a sloped surface that descends from each of the electrodes in the direction of the opposing electrode, and the angle range of the sloped surface is 50 degrees or less. 6. A method for manufacturing a liquid ejection head, wherein electric energy is converted into heat energy by a heating resistor, and the liquid is ejected by using the heat energy, according to any one of claims 1 to 5. And a step of preparing a circuit board manufactured by the method for manufacturing a circuit board, and a step of forming a discharge port for discharging a liquid corresponding to the element of the circuit board. Head manufacturing method. 7. A circuit board on which an element having a pair of electrodes facing each other with a predetermined space formed is formed, and a tilt relaxing portion of an insulating material is formed between the pair of electrodes. Circuit board. 8. A liquid ejection head for converting electric energy into heat energy by a heating resistance element and ejecting a liquid by using the heat energy, wherein a pair of the heating resistance elements are opposed to each other at a predetermined interval. A liquid discharge head, wherein an inclination-relieving portion made of an insulating material is formed between the electrodes.