JPH08267761A - Manufacture of thermal head - Google Patents

Abstract

PURPOSE: To provide a manufacturing method for a thermal head which can print at high speed, and is of low power consumption, and low cost. CONSTITUTION: The manufacturing of a thermal head comprises a first process of forming conductors 3 and 3' on a base across a heating section 2 formed on the given area on an insulation base 1, a second process of forming a resistor provided with a lower layer 4-1 composed of a tantalum nitride coating continuously the heating section 2 and conductors 3 and 3' and an upper layer 4-2 composed of tantalum and a third process of anodizing the whole of the upper layer 4-2, or the whole of the upper layer 4-2 and a part of the lower layer 4-1 of the resistor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thermal head used in an ink jet printer for generating a droplet of ink by heating and adhering the droplet onto a printing paper or the like for recording.

[0002]

2. Description of the Related Art A thermal ink jet method is one of ink jet recording methods in which a small ink droplet is generated and adhered to a recording medium such as paper for recording. The thermal inkjet system produces less noise during operation,
There is an advantage that the recording speed is high and plain paper can be used. Further, since it is possible to make color recording at a low cost, it has recently attracted attention as a personal use.

Thermal heads used in this system are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 1-145158 and 2-515. Regarding this, FIG. 3 shows the structure of the thermal head. This thermal head has a structure in which a resistor (22) is formed on a substrate (21), and conductors (23) and (23 ') are formed on the resistor (22) so as to sandwich a heating portion (26). And
Further, a protective layer (24) made of an insulating film and a cavitation resistant layer (25) made of a metal film are covered therewith.

In the thermal head having the structure shown in FIG. 3, when a pulse voltage is applied to the conductors (23) and (23 '), heat is generated in the heat generating portion (26), and the protective layer (2
4), the ink (not shown) in contact with the anti-cavitation layer (25) is heated to generate bubbles. The pressure of the bubble causes a small droplet of ink to be ejected from a nozzle (not shown) and adhere to a paper (not shown) arranged in the vicinity of the nozzle for recording.

[0005]

Generally, a thermal head used in an ink jet printer is placed in an ink atmosphere. In the thermal head having the structure as shown in FIG. 3, aluminum or copper is used for the conductors (23) and (23 ′), but these are corroded when they come into contact with ink, so the protective layer (24) is , It is necessary to prevent the invasion of ink.

The protective layer (24) is usually formed by sputtering, but the sputtering film is microscopically porous, and it is necessary to increase the film thickness when using the sputtering film as the protective layer. . For example, in the thermal head described in JP-A-1-145158, a SiO ₂ film having a thickness of 1 μm is formed as a protective layer (24) by sputtering, and the above-mentioned JP-A-2-515.
The thermal head described in Japanese Patent Publication No.
_Two films are formed by sputtering twice.

Therefore, in the conventional thermal head, since the protective layer is thick, the heat capacity of the protective layer is large, the thermal response is poor, the printing speed cannot be increased, and the input power must be increased. However, it has a problem that the power consumption is large. Further, the conventional thermal head resistor (22), conductor (23), (23
′), Protective layer (24), anti-cavitation layer (25)
Since the film is formed by sputtering, the sputtering process is required 4 or 5 times. The sputtering process has a problem that the manufacturing cost of the thermal head increases because the equipment and the sputtering target are expensive.

Therefore, the present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a method of manufacturing a thermal head capable of high-speed printing and low power consumption. Another purpose is
It is an object of the present invention to provide a method of manufacturing a thermal head that is low in cost.

[0009]

To achieve this object, a method of manufacturing a thermal head according to the present invention forms a conductor on a substrate by sandwiching a heating portion defined in a predetermined region on an insulating substrate. A first step, a second step of forming a resistor having a lower layer made of tantalum nitride and an upper layer made of tantalum, which continuously covers the heat generating portion and the conductor; It is characterized by including a third step of forming the protective layer by anodizing the entire upper layer, or the entire upper layer and a part of the lower layer. The method of manufacturing a thermal head of the present invention is characterized in that the upper layer of the resistor is formed by bias sputtering.

[0010]

In the present invention, the first step of forming a conductor on the substrate sandwiching the heat generating portion defined in a predetermined region on the insulating substrate, and continuously covering the heat generating portion and the conductor. A second step of forming a resistor having a lower layer made of tantalum nitride and an upper layer made of tantalum, and an entire upper layer of the resistor, or an entire upper layer and a part of the lower layer are anodes. Since the third step of oxidation is performed, the protective layer can be made thinner than the conventional thermal head. Therefore, the thermal capacity of the protective layer is small, the thermal response is good, and the printing speed is high. In addition, the input power is low and the power consumption is low.

[0011]

Embodiments of the present invention will be described with reference to the drawings. [Embodiment 1] A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a process diagram showing a method of manufacturing a thermal head according to the present invention, and FIG. 2 is a plan view of a thermal head manufactured by the method of FIG. In FIG. 1A, aluminum is sputtered on a silicon substrate (1) having a thermal oxide film of 1.35 μm on its surface to a thickness of 0.
A film having a thickness of 5 μm is formed, and the conductors (3) and (3) in the region surrounded by the broken line in FIG.
′) Is formed.

Next, a lower layer (4-1) of a resistor made of tantalum nitride having a thickness of 0.11 μm is formed on the conductors (3) and (3 ') by sputtering, and further thereon. After depositing an upper layer (4-2) of a resistor made of tantalum having a thickness of 0.12 μm by sputtering, a conductor (3)
Then, a resistor pattern (6) surrounded by a solid line in FIG. 2 is formed by a photolithography method so as to continuously cover the heat generating part (2) (FIG. 1B).

Next, a voltage of 165 V is applied in a 0.1% by volume phosphoric acid aqueous solution with the lower layer (4-1) and the upper layer (4-2) of the resistor as anodes, and the upper layer of the resistor ( 4-2) and part of the lower layer (4-1) are anodized to form 0.3 μm tantalum oxide as a protective layer.
1 μm tantalum nitride remains as the resistor (4) (FIG. 1 (c)).

Since the thermal head manufactured by the manufacturing method of this embodiment uses the tantalum anodic oxide film as the protective layer,
The film quality is dense, and the film thickness can be made smaller than that of the protective layer formed by sputtering in the conventional example. Therefore, 20kH
It can be driven at a high speed of z or higher, and high-speed printing becomes possible. Also, the input power required to generate bubbles is 70
The power consumption is low, which is about 0 W / mm ² . Furthermore, the number of times of sputtering film formation is three times, that is, the conductors (3) and (3 ′), the lower layer (4-1) and the upper layer (4-2) of the resistor, and the layers are anodized and protected. The upper layer (4-
Since the film thickness of 2) is thin, the sputtering time is short and the cost is lower than that of the conventional example.

[Second Embodiment] Next, a second embodiment of the present invention will be described. The upper layer of the anodizing resistor (4-
Except that the tantalum in 2) is formed by bias sputtering, it is manufactured in the same manner as in the first embodiment. Since the protective layer formed by anodizing tantalum formed by bias sputtering has a more dense film quality than the protective layer formed by anodizing a normal sputtering film as in the first embodiment, The film thickness can be reduced to 0.25 μm. As a result, power consumption is 650 W / mm
It can be reduced to about ² .

[0016]

As described above, the method of manufacturing a thermal head according to the present invention includes the first step of forming a conductor on the insulating substrate by sandwiching a heat generating portion defined in a predetermined region. A second step of forming a resistor having a lower layer made of tantalum nitride and an upper layer made of tantalum for continuously covering the heat generating portion and the conductor, and the entire upper layer of the resistor, or Since it is composed of the third step of anodizing all of the upper layer and a part of the lower layer, the thickness of the protective layer can be reduced, which results in low power consumption and high-speed printing. A thermal head with low cost can be provided. In addition, since the upper layer of the resistor is formed by bias sputtering, the power consumption can be further reduced.

[Brief description of drawings]

FIG. 1 is a process drawing showing an example of the present invention.

FIG. 2 is a plan view for explaining an embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional example of a thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Heating part 3, 3'conductor 4 Resistor 4-1 Lower layer 4-2 Upper layer 5 Protective layer 6 Resistor pattern 21 Substrate 22 Resistor 23, 23 'Conductor 24 Protective layer 25 Cavitation resistant layer

Claims (2)

[Claims] 1. A first step of forming a conductor on the substrate while sandwiching a heat generating portion defined in a predetermined region on an insulating substrate, and tantalum nitriding for continuously covering the heat generating portion and the conductor. A second step of forming a resistor having a lower layer made of a material and an upper layer made of tantalum; and a protective layer by anodizing all of the upper layer of the resistor or all of the upper layer and part of the lower layer. A method of manufacturing a thermal head, comprising a third step of forming a. 2. The method of manufacturing a thermal head according to claim 2, wherein the upper layer of the resistor is formed by bias sputtering.