JPH1016242A - Production of ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recorder of a system preventing the surface oxidation of an Ni metal membrane electrode, drastically enhancing the yield of electrical connection work, also enhanceing the reliability of connection and flying ink liquid droplets to a recording medium by utilizing heat energy. SOLUTION: In the production of an ink jet recorder supplying a pulse current to a heating resistor consisting of a TaSi-O ternary alloy membrane resistor and an Ni metal membrane conductor provided in the vicinity of an ink emitting orifice to rapidly evaporate a part of the ink in an ink liquid passage and emitting liquid droplet like ink from the emitting orifice by the expansion force of the formed air bubble to perform recording, before the thermal oxidation treatment of the heating resistor, the surface of at least an Ni metal membrane electrode for connection among an Ni metal membrane conductor and the Ni metal membrane electrode for the connection with the external circuit connected thereto is preliminarily subjected to gold plating treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method of manufacturing a recording apparatus of the type in which ink droplets fly toward a recording medium using thermal energy.

[0002]

2. Description of the Related Art An ink jet recording apparatus in which a part of ink is rapidly vaporized by pulse heating and ink droplets are ejected from an orifice by the expansion force is disclosed in JP-A-48-9622 and JP-A-54-1982. No. 51837 discloses this.

The simplest method of this pulse heating is to apply a pulse current to a thin film heater. The specific method is described in Nikkei Mechanical, December 28, 1992, p. 58, and in Hewlet.
Published in t-Packard-Journal, Aug. 1988. The basic structure common to these conventional thin film heaters is that a thin film resistor and a thin film conductor are covered with an antioxidant layer having a thickness of about 3 μm, and a thin film is formed thereon for the purpose of preventing cavitation damage of the antioxidant layer. It was intended to cover a Ta metal layer having a thickness of about 0.5 μm.

However, since the ink is pulse-heated through such a thick multilayer protective layer, the input energy required for discharging the ink reaches 15 to 30 μJ / pulse, and most of the energy is applied to the substrate (head). However, there is a major drawback that it is consumed for raising the temperature.

In order to drastically improve this, the present inventor has developed a Ta-Si-O ternary alloy thin film resistor, and thermally oxidizes the Ta-Si-O ternary alloy thin film resistor to form an electric insulating layer having a thickness of about 100 ° on its surface. Invented a method of forming a self-oxidized film having excellent properties and mechanical strength (Japanese Patent Application Nos. 07-43968 and 07-3).
No. 40486). As a result, the energy required for ink ejection is reduced to 2.4 to 2.7 μJ / pulse, and the optimal heating speed range (1 × 10
The ^{8 ~5 × 10 8 ℃ / s} ) can now be easily realized by the heater (see Japanese Patent Application No. 07-285650 by the present inventors).

On the other hand, in order to effectively use a Ta—Si—O ternary alloy thin film resistor having a self-oxidizing film, a thin film metal material for a current-carrying electrode that does not corrode even in ink is indispensable. Ni has been selected as the optimum material (see Japanese Patent Application Laid-Open No. 06-71888).

However, even with a thin film Ni conductor showing excellent corrosion resistance in the ink, it has been found that the thin film Ni conductor on the positive electrode side is easily corroded and has a problem in long-term use. On the other hand, by effectively utilizing the inorganic insulating layer and the organic insulating layer, a heater that can be used for a long time could be realized (Japanese Patent Application No. 07-43968, and 08-1 Ganpei
22091).

[0008]

As a method of manufacturing an ink jet head using a Ta-Si-O ternary alloy thin film resistor having the above-mentioned excellent characteristics, the present inventor has already shown the manufacturing method shown in FIG. The process is applied (see Japanese Patent Application Nos. 07-135185 and 07-320446).

In the process shown in FIG. 3, an ultra-thin self-oxidizing insulating film having excellent cavitation resistance is formed on the surface of the Ta-Si-O ternary alloy thin film resistor by thermal oxidation (11). be able to. At this time, 350 to thermal oxidation
Although heating at a temperature of at least ° C. is required, the surface of the Ni metal thin film conductor is also thermally oxidized at the same time, and the surface of the Ni metal thin film electrode for connection to an external circuit on this extension is also insulated. Therefore, in order to electrically connect to an external circuit,
It was necessary to remove this insulating film by dry etching or the like.

It is an object of the present invention to prevent oxidation of the surface of a Ni metal thin film electrode, dramatically improve the yield of electrical connection work, and improve the reliability of connection.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to provide an ink liquid by applying a pulse current to a heating resistor composed of a Ta-Si-O ternary alloy thin-film resistor and a Ni metal thin-film conductor provided in the vicinity of an ink discharge port. In a method of manufacturing an ink jet recording apparatus in which a part of ink in a path is rapidly vaporized and droplet ink is ejected from the ejection port by the expansion force of the bubble to perform recording, the heating resistor is subjected to thermal oxidation treatment. This is achieved by performing gold plating on at least the surface of the Ni metal thin film electrode for connection among the Ni metal thin film electrodes for connection between the Ni metal thin film conductor and an external circuit connected thereto.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a heating resistor according to the present invention.

Although the details of the structure and the manufacturing method of the ink jet print head will be omitted, the heating resistor to which the present invention is applied is a so-called thermal ink jet print regardless of whether it is a top heater type or a side heater type. It is common to heads and is applicable to both types.

First, an SiO ₂ heat insulating layer 2 having a thickness of about 2 μm is formed on the surface of a Si substrate 1. This SiO ₂ heat insulating layer 2
The Si substrate 1 may be formed by thermal oxidation,
As shown in FIG. 1A, a SiO ₂ layer 2 having a multilayer structure formed when a driver circuit 14 is formed on the same Si substrate 1.
May be used. In the latter case, the SiO ₂
An approximately 1 μm thick S is formed on the layer 2 by a plasma CVD method.
In general, an i-nitride film is formed as a passivation film. However, it is disclosed in the patent application of the inventor that this SiO ₂ / Si ₃ N ₄ two-layer film may be used as the heat insulating layer 2. This is as described in the invention (Japanese Patent Application No. 07-320446).

Hereinafter, a description will be given of an example of a head integrated with a driver circuit.

On the Si substrate 1 having the heat insulating layer 2,
As shown in (b), the Ta—Si—O ternary alloy thin film 6 and N
i metal thin films 7 are sequentially laminated by a sputtering method,
As shown in (c), the heating resistor 8 and the bonding pad 11 having a predetermined shape are formed by photoetching.

The thickness of each of the heating resistor 8 and the conductor 9 is about 0.5.
1 μm and about 0.5 μm, and the heating resistor shape is, for example, 50 μm.
m □ and the resistance value of the heating resistor 8 are slightly different depending on the composition ratio of the Ta—Si—O ternary alloy thin film.
0Ω. The composition ratio of the ternary alloy thin film studied here is 64% ≦ described in Japanese Patent Application No. 07-340486.
Ta ≦ 85%, 5% ≦ Si ≦ 26%, 6% ≦ O ≦ 15%
The range was centered.

The Ta—Si—O ternary alloy thin film 6 has a thickness of 3
A material that forms an extremely thin insulating self-oxidizing film with excellent mechanical strength of about 100 ° on its surface by thermal oxidation treatment at 50 ° C or higher, and has a sufficiently long operating life even when pulsed in electrolyte ink. Becomes For this reason, conventionally, FIG.
This thermal oxidation treatment was performed at the stage (c). However, since the surface of the Ni thin film of the bonding pad 11 was thinly oxidized in the batch treatment, it was necessary to selectively remove the oxide film by dry etching or the like. Alternatively, at the stage (c), a driving signal is applied from the bonding pad 11 and the thin film heater is pulse-heated in an oxidizing atmosphere to oxidize only the resistor. However, this has a problem in productivity, and batch processing has been desired.

Therefore, at the stage (c), the Au plating 12 was applied only to the surface of the Ni metal thin film, and thereby a method capable of performing a batch thermal oxidation treatment was developed. That is, (c)
Of the Ni thin film on the substrate is Au-plated. If, for example, HGS-100 manufactured by Hitachi Chemical Co., Ltd. is used as the replacement gold plating solution,
Au with a thickness of about 500mm only on the surface (including the side) of the Ni thin film
Can be plated. This is further immersed in an electroless Au plating solution to reduce the thickness of the Au plating to 1000 to 1500 °.
Or make it thicker. For this electroless Au plating solution, for example, HGS-2000 manufactured by Hitachi Chemical Co., Ltd. can be used.

Since the substituted Au plating adheres only to the Ni surface and the electroless Au plating adheres only to the Au surface, as shown in FIG. 1D, all of the surfaces of the Ni thin films 7, 9, and 9 'are removed. Au plating 12 is applied and does not adhere on the thin film heater 8. When this substrate is thermally oxidized at about 400 ° C.,
As shown in FIG. 1 (e), the surface of the thin film heater 8 is about 10
Since it is covered with the thermal oxide insulating film 13 having a thickness of 0 °, all the thin film surfaces (including the side surfaces) on the substrate are covered with Au or the thermal oxide insulating film.

In the present invention, the reason why the thickness of the Au plating 12 is increased as described above is that Ni and Au mutually diffuse by a distance of several hundreds of degrees by a thermal oxidation treatment at about 400 ° C. This is to prevent diffusion to the surface.

FIG. 2 shows a process of forming an ink jet device on the heater circuit integrated heater substrate (Si wafer substrate) thus formed by a thin film process. Here, FIG. 1 (a) shows a part of the cross section of the wafer after the process of FIG. 2 (8) is completed, and the thin film heater 8 and the bonding pad 11 do not correspond one-to-one, but are n heaters. On the other hand, about 6 pads correspond.

In the present invention, the introduction of the Au plating step immediately before the thermal oxidation step can be achieved by (1) batch thermal oxidation of the heating resistor, and (2) formation of ink grooves without Al coating. (The hydrazine aqueous solution is used for the etching for forming the ink groove. However, since the Ni thin film is dissolved by this, it is covered with an Al film to prevent this. This Au plating process causes (12) in FIG. , (1
(3) and (15) could be eliminated) (3) Au plating step of the bonding pad was eliminated (already plated with Au), (4) Low resistance of Ni thin film conductor (1/2 to 1/2)
(1/3)).

Of course, even in the case of a conductor plated with Au, the positive electrode is easily eroded in the electrolyte ink as in the case of the Ni conductor, whereas a thin inorganic insulating layer and an organic insulating material are used. As described above, the problem can be solved by the measure of covering the material layer.

When the produced head was filled with the aqueous ink and printed, the operation showed no change from the initial state even after the ejection of 100 million dots or more of ink. The applied power required for ink ejection is
About 2μJ / dot (2W × 1μ) with 400 dpi nozzle
Needless to say, it has a feature that is as small as s) and about 10 times smaller than that of the conventional head.

Since the cost of the Au plating process is proportional to the product of the plating area and the plating thickness, it is not always necessary to perform Au plating except for the Ni thin film of the bonding pad 11. In this case, a Ni thin film that does not require plating is coated with a resist, and only the bonding pad portion may be Au-plated. Similarly, a plating process may be performed including a common Ni thin-film conductor to reduce line resistance.

Also, due to the mutual diffusion of Au and Ni due to the heat treatment, Ni is deposited on the surface of the substituted Au plating film alone, and this is easily oxidized and passivated. Therefore, the substitution A
Add electroless Au plating for thickening on the u plating film,
The total thickness must be at least 1000-1500 °. By doing so, the workability of connection with the external circuit (connection yield, connection strength, etc.) becomes complete,
It goes without saying that the reliability is also greatly improved. Further, the rationalization of the entire head manufacturing process contributes to improving the manufacturing yield of the head and further reducing the manufacturing cost.

[0028]

[Effect of the Invention] Immediately before the thermal oxidation treatment step, the Ni thin film Au
By performing the plating process, (1) batch thermal oxidation treatment of the heating resistor is possible (2) ink grooves can be formed without Al coating treatment (3) Au plating process of the bonding pad of the prior art is entirely performed (4) Low resistance of Ni thin film conductor with large line resistance (1)
(5) The yield of connection to an external circuit and the improvement of reliability were achieved, and the improvement of the manufacturing yield of the head and the reduction of the manufacturing cost were also achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a heater substrate showing an example of the present invention in the order of steps.

FIG. 2 is a flowchart illustrating a head manufacturing process according to an example of the invention.

FIG. 3 is a flowchart showing a conventional head manufacturing process.

[Explanation of symbols]

1 is a Si substrate, 2 is a SiO ₂ layer, 3 is a driver circuit A
l wiring, 4 is a through hole for bonding pad, 6
Is a Ta-Si-O ternary alloy thin film, 7 is a Ni metal thin film, 8
Is a heating resistor, 9, 9 'are wiring conductors, 10 is a connecting portion, 1
1 is a bonding pad, 12 is an Au plating film, 13
Denotes a self-oxidized film, and 14 denotes a device portion of the driver circuit.

Claims (1)

[Claims] 1. A Ta-Si provided near an ink discharge port.
A part of the ink in the ink liquid path is rapidly vaporized by applying a pulse current to a heating resistor composed of a -O ternary alloy thin film resistor and a Ni metal thin film conductor, and the expansion force of the bubble causes the liquid to flow out of the discharge port. In the method of manufacturing an ink jet recording apparatus for discharging and recording ink droplets, the Ni metal thin film conductor is connected to an external circuit connected to the Ni metal thin film conductor before the heating resistor is thermally oxidized. A method for manufacturing an ink jet recording apparatus, characterized in that at least the surface of a connecting Ni metal thin film electrode is subjected to gold plating.