JPS6038001B2 - thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head having a thin film heating resistor made of shelved vanadium and oxygen, and also to a method for manufacturing the same.

A thermal head used for thermal print recording includes a plurality of heating resistors on a substrate having electrical insulation and a smooth surface, such as glass, and an electric conductor for supplying power to the heating resistors. Recording is performed by applying a current to the corresponding heat-generating resistor through an electric conductor to generate heat so as to obtain a necessary thermal pattern according to the information to be recorded, and bringing the heat-generating resistor into contact with the recording medium.

Heat generating resistors used therein include conventional thin film heat generating resistors such as tantalum nitride and dichrome tin oxide, thick film heat generating resistors using silver-palladium, etc., and semiconductor heat generating resistors using silicon semiconductor. Among these, thermal heads using thin film heating resistors have better thermal response, superior heat resistance and thermal shock resistance, longer lifespan, and higher reliability than thick film heating resistors, semiconductor heating resistors, etc. It has the following characteristics.
Conventionally, tantalum nitride has been used for this thin film heating resistor, which has excellent heat resistance, high reliability, and has a specific resistance value of 250 to 3.
It is particularly widely used because it has a relatively high value of 0.00 french ○c and good controllability in manufacturing. However, tantalum nitride is rapidly oxidized at high temperatures of about 30,030° C. or higher, resulting in a rapid increase in its resistance value, which has the disadvantage of deteriorating print density when printing on recording paper.

Generally, silicon oxide (Si02) is used to compensate for this drawback.
) is provided with an oxidation-resistant protective layer of tantalum oxide (T
A2Q) was provided with a wear-resistant layer and used as a thermal head, but the change in resistance when the thermal head was driven for a long time was still not fully satisfactory. In particular, in recent years, the demand for high-speed thermal heads has increased, so it is necessary to shorten the energizing pulse of the head to color the thermal paper, which means that the power consumption is higher than before.
Since the heating resistor becomes even hotter, its life becomes shorter. Therefore, there is a demand for a heating resistor with even higher heat resistance. Also, the sheet resistance of tantalum nitride is usually 500/
Before and after the mouth, "Even if it is made especially large as a thermal head, the resistance value is about 10000/0. In order to further increase the resistance value, methods such as trimming or thinning the film thickness are used, but the manufacturing process is complicated. However, disadvantages may occur, such as damage to the product or an adverse effect on the service life.

In this way, the tantalum nitride thin film heating resistor cannot have a large sheet resistance, so in order to supply enough power to heat the resistor, the current inevitably becomes large, and the resistance value of the electrical conductor becomes a problem. Become.

In other words, since the resistance value of the electrical conductor cannot be ignored compared to the resistance value of the thin-film heating resistor, the amount of heat generated by each resistor will differ due to the difference in the distance between each electrical conductor connected to the resistor, and the recording Differences in density occur in the pattern, resulting in poor recording quality. Furthermore, if the size of the thin film heating resistor is reduced in order to increase the recording density, the sheet resistance value of the thin film heating resistor remains unchanged and only the resistance value of the electrical conductor increases, so power consumption in the electrical conductor becomes a problem. Furthermore, if the thickness of the electrical conductor is made extremely large in order to avoid this, in the case of multi-layer wiring, the surface becomes extremely uneven and becomes susceptible to abrasion, resulting in major structural problems. Also, if the current is large, it is a heating power source,
Inconveniences also arise, such as the need to increase the capacity of switching circuits and the like. The present invention improves the above points and provides a thermal head using a thin film heating resistor that is resistant to oxidation, has a stable resistance value, and allows the specific resistance to be selected up to a high value.
Its feature lies in the heating resistor made of shelved vanadium and oxygen.

In this heating resistor, shelved vanadium and oxygen are mixed on an atomic scale. A detailed description will be given below with reference to the drawings.

FIG. 1 is a sectional view of a main part of an example of the shape of a thermal head applied to the present invention. 1 in the figure is a substrate made of an electrical insulator such as ceramics, glass, or glazed ceramics. 2 is a thin film heating resistor according to the present invention, which is made of shelved vanadium and oxygen.

Reference numeral 3 denotes an electric conductor for supplying power to the thin film heating resistor, and is made of a good electric conductor such as aluminum or gold.

4 is a protective layer for the thin film heating resistor and electric conductor, for example, silicon oxide, magnesium oxide, aluminum oxide, tantalum oxide, or a multilayer structure made of a combination of these, which is manufactured by electron beam evaporation, sputtering, etc., is used. This makes it possible to further extend the life of the thermal head. The thin film heating resistor of the present invention made of shelved vanadium and oxygen can be manufactured by either sputtering or electron beam evaporation. A method of sputtering sputtering, a method of targeting shelf elements and metal vanadium at the same time, a method of sputtering metal vanadium alone, a method of sputtering argon, oxygen,
There is a method of performing active sputtering in an atmosphere containing diborane. When using shelved vanadium as a target, for example, it can be used as a target by placing the shelved vanadium in a powdered or pressed state on a quartz dish, etc., but it can be used as a target by placing the shelved vanadium in a powdered or pressed state on a quartz plate or the like. It is easier to control sputtering by using a target that has been adjusted.

In addition, when shelving and metal vanadium are targeted at the same time, the shelving and metal vanadium can be mixed, or one can be embedded in the other or placed on a part of the surface. In either case, 1×10-juice orr~
It is best to carry out in a mixed atmosphere of argon and oxygen at 5×lo-ITorr, preferably 1×10-Tom to 1×1
0-ITorr key is good. In addition, when active sputtering is performed using metal vanadium as a target in a mixed atmosphere of argon, oxygen, and diborane, the total gas pressure is 1×1.
Gebiorr~5×10-ITon, preferably 1×10
-2rorr to 5x10-2 Tom, in which the partial pressure of diborane is 1 to 10% of the total pressure, preferably 2 to 6%.

During any of the above sputtering processes, by selecting the oxygen partial pressure in the atmosphere from 0.1 to 10%, oxygen is added to the heating resistor at an atomic ratio of 0.00% to that of vanadium.
5 or more can be contained.

If the oxygen content is too low, it will not be effective, and if it is too high, it will be difficult to control the resistivity and the heat resistance will deteriorate, so 0.01 to 1.0 (atomic ratio) of vanadium is appropriate. ．．
05 to 0.6 is more preferable, and 0.1 to 0.3 is most preferable. The specific resistance value of the heating resistor thus prepared can be selected from 150 Q arc to 5000 F arc. When manufacturing a heating resistor by electron beam deposition, a tablet is made by pressing magnetized vanadium powder at a pressure of about 100 kg/water or more, and the temperature is kept at a constant temperature in advance at a high vacuum of 1 x 10-4 Torr or more. It can be deposited on a substrate.

At this time, the oxygen content in the heating resistor can be adjusted to 0.005 to 1.0 (atomic ratio) of vanadium by introducing a gas containing oxygen into the fin beam vapor deposition using a needle valve or the like. can. The thin film heating resistor created in this way is made of shelved vanadium and oxygen (contains C.N., etc. as impurities), and if the specific resistance value is set high, even if the resistance value of the electrode part is high to some extent. This makes the manufacturing process easier, and by making the electrode thinner, the wear resistance is improved due to fewer surface irregularities.

In addition, since the voltage drop at the electrode portion is negligible, uneven color density due to uneven heating of the thin film heating resistor is also reduced, and electrode patterns such as matrix wiring can be designed more freely. Furthermore, by heating the substrate to 200 qo to 500 qo during sputtering or electron beam evaporation, the adhesion between the substrate and the thin film heating resistor is improved, which is effective in improving the stability of the film.

Next, an explanation will be given based on an example.

(Example 1) Using a 5-inch diameter magnetized vanadium VB target (manufactured by Research Corporation, USA, purity 99%) hot-pressed at 1100 qo, a thoroughly cleaned glazed alumina substrate with a glass thickness of 50 mm was heated at 300°C. While heating the substrate, the argon pressure was 4×10-2T, the oxygen pressure was 3×10-3T.
High frequency bipolar sputtering was performed in a mixed gas atmosphere.

When sputtering was performed for 5 minutes at a sputtering rate of 200 A/min and an input power of 3.0 W/min, a thin film heating resistor with a thickness of 1000 A was obtained. The specific resistance was 1200 mm, and the area resistance was 1200/mouth. When the composition of this film was investigated using an ion microanalyzer, oxygen was found to be 0% of vanadium.
．． It contained 23 (atomic ratio). 1 mountain of titanium A on this
, aluminum was applied by lAm electron beam evaporation, and a thermal head pattern with a resolution of 4 lines/side was formed by selective etching, and this was designated as thermal head A. Furthermore, 1 layer of silicon oxide (Si02) is applied as a protective layer on top of this.
Tantalum oxide (Ta205) was continuously laminated by sputtering and thermally deposited. For comparison, tantalum was targeted by high-frequency bipolar reactive sputtering, and the total pressure of argon and nitrogen was 8 × 10
-2 Tom, 1 under the condition that the nitrogen partial pressure is 1 x 10-4 Ton.
A thermal head B of a tantalum nitride thin film heating resistor with a thickness of 000 Å was fabricated. This tantalum nitride thin film heat generating resistor had a specific resistance of 260 mm and an area resistance of 260 mm. For the thermal head B, silicon oxide (Si02) was further applied as a protective film, and tantalum oxide (1Am) was applied as a protective film.
10 m of Ta205) were continuously laminated by sputtering to form a thermal head &. These thermal heads were subjected to an acceleration test using a rectangular wave of 8 hs at 50 Hz while increasing the power of IW/Kyo every 30 minutes.

The results are shown in FIG. As is clear from the figure, it was found that the thermal head having the thin film heating resistor produced by the manufacturing method according to the present invention could withstand high applied power and had little change in resistance at high temperatures. In other words, while it is surprising that the comparative example can be used without a protective film, the thermal head according to the present invention can be put into practical use without a protective film, and when a protective film is attached, very good heat resistance can be obtained. Ta. (Example 2) Using a 6-inch diameter shelved vanadium (V&) target hot-pressed at 1300 oo, a thoroughly cleaned glazed alumina substrate with a glass thickness of 50 m was heated to 20 and 0. Argon pressure 4×10-orr,
High-frequency bipolar sputtering was performed in a mixed gas atmosphere with an oxygen pressure of 4×10-3 Ton.

When sputtering was performed for 3 minutes at a sputtering rate of 200 A/min and an input power of 3.0 W/min, a thin film heating resistor of the present invention having a film thickness of 600Δ was obtained. The specific resistance was 2300 rQ, and the area resistance was 3900/mouth. 1 vanadium on top of this
0△, 1 mm of aluminum was applied by electron beam evaporation, a thermal head pattern with a resolution of 4 lines/side was formed by selective etching, and on top of this, silicon oxide (Si02) was added as a protective layer with 2 peaks of oxidation. Aluminum (AI
203) was continuously laminated for 5 rms by sputtering to create a thermal head. When this thermal head was subjected to the same acceleration test as in Example 1, results similar to those of the thermal head were obtained.

(Example 3) A target was prepared by using a large number of 1/4 inch diameter boron plates bonded together on a 6 inch diameter metal vanadium slope so that the surface area ratio of metal vanadium to shelving was approximately 1:2. Using.

500 thoroughly cleaned glazed ceramic substrates
The substrate was heated to 0.degree. C., argon pressure: 3×10-2Ton, oxygen pressure 2×LO-T orr, and RF. Sputtering was performed using two electrodes.
When sputtering was carried out for 8 minutes at a sputtering rate of 100 A/min, a thin film heating resistor with a film thickness of 800 A, a specific resistance of 1000 peaks, and a sheet resistance of 1250/hole was obtained. After evaporating titanium at 10A and aluminum using a 1F electron beam, a thermal head pattern having a resolution of 4 lines/side was formed by selective etching. Next, as a protective film, a mirror layer of magnesium oxide (Mg0) loAm was formed by sputtering.
When this thermal head was subjected to the same acceleration test as in Example 1, the resistance change rate was ±2 up to 21.5W/fence.
%, very good results were obtained compared to thermal heads using tantalum nitride.

(Example 4) A metal vanadium plate with a diameter of 6 inches was used as a target.

400 thoroughly cleaned glazed ceramic substrates
The substrate was heated to qC and active sputtering was performed in a mixed gas atmosphere of argon, diborane, and oxygen. The total pressure of argon + diborane + oxygen is 3.5 × 10-5 Ton,
Diborane partial pressure is 1.5 x 10-4 Tort, oxygen partial pressure is 1
×10-4Ton with high frequency 2-pole sputtering 1000△
A film thickness of . The sheet resistance was 500/mouth (specific resistance value was 500 FQ). 10 vanadium on top of this
After evaporating 0A and gold using a 1F electron beam, a thermal head pattern with a resolution of 4 lines/layer was formed by selective etching. Next, aluminum oxide (N2
03) loAm was laminated by sputtering.

When this thermal head was subjected to the same acceleration test as in Example 1, the resistance change rate was 2% up to 21W/masu.
It was within This example also gave much better results than the thermal head using kenka tantalum in the comparative example. (Example 5) A tablet was made by pressing shelved vanadium powder at a pressure of 100k9/carp or more, and the tablet was placed on a glazed ceramic substrate that had been thoroughly cleaned in advance, and the substrate was heated at 300 pm and evacuated to a vacuum level of 2 x 10-6 Ton. After straining, the vacuum level is 5 x 10-6T while introducing dry air with a needle valve.
The film was deposited using an electron beam to a thickness of 1000A.

The area resistance was about 700/mouth (specific resistance value was about 700 French skin). Next, after depositing titanium at 10 A and aluminum at 1.5 m by an electron beam using an electron beam, a pattern with a resolution of 4 lines/side was formed by selective etching, and silicon oxide (Si02) was deposited at 1 m by an electron beam. A thermal head was fabricated by continuously depositing tantalum oxide (Ta205) in a thickness of 10 m by sputtering. When this thermal head was subjected to the same acceleration test as in Example 1, good results similar to those of the thermal head were obtained.

When the composition of this film was examined using an ion microanalyzer, it was found that 0.16 (atomic ratio) of oxygen and vanadium was contained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an example of the shape of a thermal head according to the present invention. FIG. 2 is a characteristic diagram showing the effects of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Thin film heating resistor, 3... Electric conductor, 4... Protective layer. Chrysanthemum Diagram 2

Claims (1)

[Scope of Claims] 1. A thermal head having a substrate, a heating resistor formed on the substrate, and an electric conductor for supplying power to the heating resistor, in which the heating resistor is made of vanadium boride and oxygen. A thermal head characterized by comprising: 2 The oxygen content in the heating resistor is 0 of vanadium.
．． 005 (atomic ratio) or more. 3 The oxygen content in the heating resistor is 0 of vanadium.
．． 01 to 1.0 (atomic ratio). 4. The thermal head according to claims 1 to 3, wherein the heating resistor is covered with a silicon oxide thin film. 5 Claim 1 having a tantalum oxide protective film
The thermal head according to items 1 to 4. 6. The thermal head according to claims 1 to 4, which has a protective film of aluminum oxide. 7. The thermal head according to claims 1 to 4, which has a protective film of magnesium oxide. 8. A method for manufacturing a thermal head, characterized in that a heating resistor made of vanadium boride and oxygen is manufactured by sputtering. 9. The manufacturing method according to claim 8, wherein sputtering is performed in a mixed gas containing argon and oxygen. 10. The manufacturing method according to claim 8 or 9, wherein the sputtering target is hot-pressed vanadium boride. 11. The manufacturing method according to claim 8 or 9, wherein metal vanadium and boron are arranged so as to be targeted simultaneously. 12. The manufacturing method according to claim 8, wherein sputtering is performed in a mixed gas containing argon, oxygen, and diborane. 13. The manufacturing method according to claim 12, which targets metal vanadium. 14. The manufacturing method according to claims 8 to 13, wherein sputtering is performed while heating the substrate at 200°C to 500°C. 15. A method for manufacturing a thermal head, characterized in that a heating resistor made of vanadium boride and oxygen is manufactured by electron beam evaporation. 16. The manufacturing method according to claim 15, wherein electron beam evaporation is performed while introducing a gas containing oxygen. 17 Claim 15 or 16 in which electron beam evaporation is performed while heating the substrate at 200°C to 500°C
Manufacturing method described in section.