JPH07132629A - Thermal head and production thereof - Google Patents

Abstract

PURPOSE:To provide a thermal head equipped with heating resistors good in oxidation resistance at high temp. even when a protective layer having oxidation resistance is not applied and showing a long life and high reliability. CONSTITUTION:In a thermal head wherein a heat insulating layer 2 is formed on the surface of a substrate 1 and a plurality of heating resistors 3 and the individual electrodes 4b and common electrodes 4a connected to the heating resistors 3 are formed to the end parts of the substrate 1, each of the heating resistors 3 is formed from a membrane composed of Si-Mo-O.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film type thermal head for thermal recording, and more particularly to a thermal head having a heating resistor having good oxidation resistance and long life, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a thermal head mounted on a thermal printer, a plurality of heating resistors are linearly arranged on a substrate, and one of the heating resistors is selectively energized sequentially according to desired printing information. By heating the portion (dot) that contributes to the central part of the heating resistor in the longitudinal direction, the thermal recording paper is colored in the thermal printer, and the ink of the ink ribbon is partially melted in the thermal transfer printer and transferred to the plain paper. Then, it is designed to print.

The thermal head is classified into a thin film type and a thick film type according to the method of forming the heating resistor. As the thin-film heating resistor, tantalum nitride, which is composed of a nitride of tantalum and a protective layer of an oxide having oxidation resistance formed thereon, is the most common and is extremely stable and changes with time. It is well known that it exhibits the property of being low. However, this tantalum nitride is approximately 300 ° C.
Since it also has the property of being oxidized in the above and lacks oxidation resistance, the heating resistor of the thermal head is covered with a protective layer having excellent oxidation resistance such as silicon oxide, and tantalum pentoxide is also added. Etc. was coated with a wear resistant layer.

[0004]

However, the protective layer for preventing the thermal head formed in this way from being oxidized has a problem that the film thickness becomes thick and the number of manufacturing processes increases. When the thickness of the layer is reduced, there is a problem in that the probability of microcracks in the protective layer during printing increases and the printing life is shortened due to oxidation of the heating resistor.

Further, the resistivity of the heating resistor is approximately 200 to 3
Since it is as small as about 00 μΩ-cm, in order to obtain a desired dot resistance value as a thermal head, the film thickness thereof should be about 30.
It is desirable to make the thickness as thin as 0 angstrom, but when the thermal head is operated for a long time, the change in resistance value due to the thickness of the oxide layer on the surface of the heating resistor cannot be ignored due to the heat generated by itself. There was a point.

As a thermal head provided with a heating resistor using tantalum nitride, a thermal head using a refractory metal silicide, carbide, boride or the like as a heating head has been improved. Sho 52-10994
No. 7, but the thermal head described in this publication does not always give satisfactory results.
Since an increase in resistance value due to oxidative deterioration at high temperatures is unavoidable, it has been indispensable to coat with a protective layer having oxidation resistance in order to provide long life and high reliability for high speed recording.

The present invention provides a thermal head provided with a heating resistor having good oxidation resistance at high temperature, long life and high reliability without providing a protective layer having oxidation resistance, and a method for manufacturing the same. The purpose is to provide.

[0008]

In order to achieve the above object, the thermal head of the present invention has a heat insulating layer formed on the surface of a substrate, and a plurality of heat generating resistors are provided at the end of the substrate, and a heat generating resistor for each of them. In a thermal head having an individual electrode and a common electrode connected to a resistor, the heating resistor is formed of a thin film of Si-Mo-O.

According to a second aspect of the present invention, there is provided a method of manufacturing a thermal head in which a heat insulating layer is formed on a surface of a substrate, a plurality of heating resistors are provided at an end of the substrate, and individual electrodes connected to the heating resistors. 2. The thermal head according to claim 1, wherein the thermal head comprises a common electrode and a common electrode.
i and a sputtering target composed of approximately 15 to 25 mol% of Mo, and an O ₂ gas flow rate of approximately 1 to 10%.
O ₂ reactive sputtering is performed within the range of
It is characterized in that a Mo—O thin film is formed, and high-temperature heat treatment is performed in an oxidizing atmosphere to form a heating resistor.

[0010]

According to the above-described thermal head of the present invention, since the Si-Mo-O thin film is formed as the heating resistor, it has a sufficiently large resistivity of 1 to 70 mΩ-cm. Body thickness of about 2000-50
Within the range of 00 angstrom, it is possible to easily design from low resistance to high resistance. In addition, in the manufacturing method, since high-temperature heat treatment is performed in an oxidizing atmosphere in advance, it is possible to completely ignore the effect of oxidation of the surface protective layer of the heating resistor that is generated by heat generation by itself, and ensure thermal stability. You can

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view showing the structure of the thermal head of the present invention.

Insulating substrate 1 such as ceramic substrate
A heat insulating layer 2 made of glass or the like is formed on the upper surface of the substrate 1. On the upper surfaces of the substrate 1 and the heat insulating layer 2, a plurality of heating resistors 3 are linearly formed by sputtering. Also, a common electrode 4a connected to each heating resistor 3 is laminated on one side of the upper surface of the heating resistor 3, and each heating resistor 3 is independently energized on the other side of the upper surface. The individual electrodes 4b are stacked. Therefore, the dots 3a, which generate heat when energized and contribute to printing, are formed in the central portion of each heating resistor 3 in the longitudinal direction. Furthermore,
On the upper surfaces of the heat retaining layer 2, the heating resistor 3, the common electrode 4a and the individual electrode 4b, the heating resistor 3 and the electrodes 4a,
A protective layer 5 for protecting 4b is formed, and this protective layer 5 covers all surfaces of the electrodes 4a, 4b except the terminal portions.

Next, the heating resistor 3 in the present embodiment.
The manufacturing method of will be described.

First, the heat retaining layer 2 formed on the upper surface of the substrate 1.
75-85 mol% Si on the surface of
Using a sputtering target composed of mol% Mo, O ₂ gas flow rate within the range of approximately 1 to 10%
₂ Reactive sputtering is performed to form a Si-Mo-O thin film. Then, the Si—Mo—O thin film is subjected to high temperature heat treatment in an oxidizing atmosphere to forcibly oxidize the surface. By doing so, it is possible to form the heat generating resistor 3 in which the oxidation resistance at high temperature and the resistance value are further stabilized.

Next, the operation of this embodiment will be described.

Si-Mo with O ₂ flow rate of 1 to 10%
Heating resistor consisting of -O thin film, when it was heat-treated at a high temperature, generally of Cermet resistors (Ta-SiO ₂₎ Whereas for resistivity reduced by annealing effect, resistivity Conversely increases Characteristically, the O ₂ gas flow rate is 10
%, The characteristic is that the fluctuation of the resistivity due to the heat treatment is small and the reproducibility is excellent. However, when the O ₂ gas flow rate is further increased to 10% or more, the resistivity of Si—Mo—O shows a sharp increasing tendency,
It has been found that in this region, the variation in resistivity due to film formation and heat treatment becomes extremely large and the reproducibility is poor, so that it is not suitable for forming a heating resistor of a thermal head. This is proved by the next experiment.

FIG. 2 is a graph showing the results of measuring the resistivity with respect to the flow rate of O ₂ gas while changing the composition ratio of Si and Mo.

First, in a mixed gas of Ar and 5% or 10% O ₂ , the composition ratio of Si and Mo is 75:25 mol%.
A heating resistor was formed by reactive sputtering using the sputtering target
When heat treatment is performed for 3 hours in the oxidizing atmosphere of
Line), the resistivity thereof is approximately 2 mΩ-cm, and the film thickness, which was conventionally about 300 Å for tantalum nitride, can be increased about 10 times to about 3000 Å.

Next, when a heating resistor is formed by reactive sputtering using a sputtering target having a composition ratio of 85:15 mol%, and the same heat treatment is performed (line B in the figure), the resistance The rate is almost 70
It became mΩ-cm, and it became easy to make the dot resistance value a high resistance of 1000Ω or more.

That is, the heat-generating resistor made of the Si-Mo-O thin film has a small variation in the resistivity due to film formation and heat treatment in the region where the O ₂ gas flow rate is 1 to 10% and is excellent in reproducibility. It is suitable for forming the heating resistor, and by changing the composition ratio of Si and Mo, it is possible to obtain an arbitrary value in the range of about 1 to 70 mΩ-cm. That is, according to the present embodiment, it is possible to obtain a resistivity much higher than that of the metal nitride which has been widely used for the heating resistor of this type conventionally.

Since the amount of O ₂ added to the film of the heating resistor can be continuously and easily controlled by changing the flow rate ratio of Ar and O ₂ introduced during sputtering, the resistance of the heating resistor is reduced. The rate can be controlled easily.

The processing of the deposited film is (CF ₄ + O
₂ ) Reactive ion etching (RI
E) or chemical dry etching (CDE), the material is suitable for a thermal head having excellent fine workability. Further, the heating resistor of the present invention has a temperature coefficient of resistance ( Since the TCR is smaller than that of a cermet type (for example, Ta-SiO ₂ ), it is suitable as a heating resistor for a thermal head in that respect as well.

By using the heating resistor thus formed, the oxidation-resistant protective layer for preventing oxidation, which has been conventionally required, can be omitted, and the manufacturing process of the thermal head can be shortened. Further, since the protective layer can be easily thinned, there is an advantage that the thermal efficiency in printing can be improved. Further, by performing high temperature heat treatment in an oxidizing atmosphere, it is possible to prevent deterioration of characteristics at high temperatures,
Therefore, it is possible to configure a thermal head having high reliability even in high-speed recording.

The present invention is not limited to the above embodiment, but can be modified as necessary.

[0026]

As described above, since the thermal head of the present invention is constructed and operates, the oxidation-resistant protective layer, which has been conventionally required, can be omitted, and the manufacturing process of the thermal head can be shortened. In addition, since the protective layer can be easily thinned, there is an advantage that the thermal efficiency in printing can be improved. Further, according to the manufacturing method of the present invention, since the heat generating resistor is formed by performing high temperature heat treatment, there is no deterioration of characteristics at high temperature, and therefore a thermal head having high reliability and long life in high speed recording can be provided. Produce an effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a thermal head of the present invention.

2 is a graph showing the results of measuring the resistivity with respect to the O ₂ gas flow rate by changing the composition ratio of Si and Mo of the heating resistor of the embodiment of FIG.

[Explanation of symbols]

 1 substrate 2 heat insulation layer 3 heating resistor 3a dot 4a common electrode 4b individual electrode 5 protective layer

Claims (2)

[Claims] 1. A thermal head comprising a heat insulating layer formed on the surface of a substrate, and a plurality of heating resistors formed at the end of the substrate, and individual electrodes and common electrodes connected to the heating resistors. In the thermal head, the heating resistor is formed of a thin film of Si-Mo-O. 2. A thermal head comprising a heat insulating layer formed on the surface of a substrate, and a plurality of heating resistors formed at the end of the substrate, and individual electrodes and common electrodes connected to the heating resistors. In the above, a sputtering target composed of approximately 75 to 85 mol% of Si and approximately 15 to 25 mol% of Mo was used, and O ₂ reactive sputtering was performed at an O ₂ gas flow rate in the range of approximately 1 to 10%. -O
2. The method of manufacturing a thermal head according to claim 1, wherein a thin film is formed and a high temperature heat treatment is performed in an oxidizing atmosphere to form a heating resistor.