JPS6038009B2 - 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 niobium 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. A device is installed in which a current is passed through the corresponding heat-generating resistor through an electric conductor to generate heat in order to obtain the necessary heat pattern according to the information to be recorded, and the record is recorded by contacting the recording medium. be. 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 300 μm.
It is particularly widely used because it has a relatively high value of c and good manufacturing controllability. However, tantalum nitride is about 300o
At high temperatures above 1000 yen, it is rapidly oxidized and its resistance value increases rapidly, which has the disadvantage of deteriorating the 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/
Even if the thermal head is made especially large before and after the mouth, the resistance value is about 1000/mouth, and 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.

As described above, the tantalum nitride thin film heating resistor cannot have a large sheet resistance, so in order to supply enough power to heat the resistor, a large current is inevitably required, and the resistance value of the electric conductor becomes a problem.

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 characteristic feature is a heating resistor made of shelved niobium and oxygen.

In this heating resistor, shelved niobium and oxygen coexist 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 niobium and oxygen.

Reference numeral 3 denotes an electric conductor for supplying power to the thin film heating resistor, which 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, a multilayer structure made of silicon oxide, magnesium oxide, aluminum oxide, tantalum oxide, or a combination of these, manufactured by electron beam evaporation, sputtering, etc., is used. The life of the thermal head can be further extended. The thin film heating resistor of the present invention made of shelved niobium and oxygen can be manufactured by either sputtering or electron beam evaporation.The sputtering method uses a shelved niobium target in a mixed atmosphere of argon and oxygen. There are methods such as sputtering using niobium as a target, a method using niobium metal as a target at the same time, and a method using active sputtering using only niobium metal as a target in an atmosphere containing argon, oxygen, and diborane. When using shelved niobium as a target, for example, it can be used as a target by placing shelved niobium in a powdered or pressed state on a quartz plate, etc., but it is possible to use it as a target by placing shelved niobium in a powdered or pressed state on a quartz plate, etc. It is easier to control sputtering by using a target.

In addition, when using shelving element and metallic niobium as targets at the same time, it can be carried out by mixing the side element and metallic niobium, or by embedding one in the other or disposing one on a part of the surface. In either case 1×10-汀orr〜5×10
-ITorr in a mixed atmosphere of argon and oxygen, preferably 1 x 10- or on to 1 x 10-IT
orr is good. In addition, targeting metal niobium,
When performing active spartering in a mixed atmosphere of argon, oxygen, and diborane, the total gas pressure is 1 x 10-2 Ton ~
5×10-ITon, preferably 1×10-2Tom~
5×10 −2 Ton, in which the partial pressure of diborane is 1 to 10%, preferably 2 to 6% of the total pressure.

During any of the above spuckling processes, by selecting the oxygen partial pressure in the atmosphere from 0.1 to 10%, it is possible to make the heating resistor contain oxygen in an atomic ratio of 0.005 or more compared to niobium. can. 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 specific resistance and the heat resistance will deteriorate, so 0.01 to 1.0 (atomic ratio) of niobium is appropriate, and 0.05 -0.6 is more preferable, and 0.6 is more preferable.
1 to 0.3 is most preferred. The specific resistance value of the heating resistor thus prepared can be selected from 100 peaks ○c to 5000 squares Q arc. When manufacturing a heating resistor by electron beam evaporation, tablets are made by pressing shelved niobium powder at a pressure of about 100 k9/m or more, and a 1×10-4 T.
It can be deposited on a substrate that has been kept at a constant temperature in advance at a high degree of vacuum (on or higher). At this time, the oxygen content in the heating resistor is reduced to zero by introducing oxygen-containing gas into the electron beam evaporation using a needle valve or the like.
．． 005 to 1.0 (atomic ratio). The thin film heating resistor created in this way is made of shelved niobium 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, surface irregularities are reduced and wear resistance is improved.

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, heating the substrate to 200 to 50,000 degrees Celsius during sputtering or electron beam evaporation improves the adhesion between the substrate and the thin film heating resistor, which is effective in improving the stability of the film.

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

(Example 1) Using a target of 5-inch diameter shelved niobium Nb horse (manufactured by Pentron, USA, purity 99.8%) hot-pressed at 1100 qo, thoroughly cleaned glass with a thickness of 50 m
A glazed alumina substrate of
- High frequency bipolar sputtering was performed in a mixed gas atmosphere at -3 Torr.

When sputtering was carried out 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 film thickness of 1000 A was obtained. The specific resistance was 700 f/fox, and the area resistance was 700/mouth. When the composition of this film was examined using an ion microanalyzer, the oxygen content was 0.22% of that of tantalum.
(atomic ratio) included. On top of this, titanium 10A and aluminum were deposited by lAm electron beam evaporation, and a thermal head pattern having four decomposition holes per side was formed by selective etching, and this was designated as thermal head A. Furthermore, silicon oxide (Si02) was added as a protective layer on top of this to a thickness of 1 Am.
Ten meters of tantalum oxide (Ta205) was continuously deposited by sputtering to form a thermal head. For comparison, tantalum was targeted by high-frequency bipolar reactive sputtering, and the total pressure of argon and nitrogen was 8 × 10-2 T.
on, 1000 at a nitrogen partial pressure of 1×10-4Ton.
A thermal head B of a tantalum nitride thin film heating resistor having a thickness of A was fabricated.

This tantalum nitride thin film heating resistor has a specific resistance of 260F.
The area resistance of the skin was 260/mouth. Thermal head B
, silicon oxide (Si02
) and 10 m of tantalum oxide (Ta205) were continuously laminated by sputtering to form a thermal head &. An acceleration test was performed on these thermal heads while increasing the power of &hs square waves at 50Hz every 30 minutes by lw/hs.

The results are shown in FIG. As is clear from the figure, it was found that the thermal head having a thin film heating resistor produced by the manufacturing method according to the present invention can withstand high applied power and has little change in resistance at high temperatures. In other words, while the comparative example is difficult to put into practical use without a protective film, the thermal head according to the present invention can be put into practical use without a protective film.
When a protective film was attached, very good heat resistance was obtained.
(Example 2) Using a 6-inch diameter shelved niobium target hot-pressed at 1300 oo, thoroughly cleaned glass with a thickness of 5
200 glazed alumina substrates of 0 French m were heated to 0, and the argon pressure was 4 x 10-2 Tom and the oxygen pressure was 4 x
High frequency bipolar sputtering was performed in a mixed gas atmosphere of 10-3 tons.

The sputtering rate was 200 μm/min, and the input power was 3. Sputtering was carried out for 3 minutes using a sail/metal method, and a thin film heating resistor of the present invention having a film thickness of 600△ was obtained. The specific resistance was 1300 shipboard Q skin, and the sheet resistance was 2150/0. 1 vanadium on top of this
0A aluminum was attached by lAm electron beam deposition, a thermal head pattern with a resolution of 4 lines/rib was formed by selective etching, and on top of this a protective layer of silicon oxide (SiQ) and aluminum oxide (AI2Q) were formed.
) was continuously sputtered into a thin layer of 5 m to create a thermal head. 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.

(Example 3) A target in which a large number of sintered 1'4 inch diameter boron plates were placed on a 6 inch diameter metal niobium plate so that the surface area ratio of metallic niobium to shelf elements was approximately 1:2. was used.

500 thoroughly cleaned glazed ceramic substrates
The substrate was heated to
At an oxygen pressure of 2×10-3 Tom, R. F. It sputtered on two poles. When sputtering was performed 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 value of 600 Q, and a sheet resistance of 750/hole was obtained. After evaporating titanium (10A) and aluminum (1 m) using an electron beam, selective etching was performed to form a thermal head pattern with a resolution of 4 lines/side. Next, as a protective film, 10 m of magnesium oxide (Mg0) was deposited by sputtering. When this thermal head was subjected to the same acceleration test as in Example 1, the resistance change rate was within ±2% up to 22.5W/fence, which was very good compared to the thermal head using tantalum nitride. The results were obtained.

(Example 4) A 6 inch diameter metal niobium plate was used as a target.

Thoroughly cleaned glazed ceramic substrate
The substrate was heated to 0.degree. C., and active sputtering was performed in an atmosphere of a mixed gas of argon, diborane, and oxygen. The total pressure of argon, diborane, and oxygen is 3.5 x 10-2 Tom, and the partial pressure of diborane is 1.5 x 10-4 Tor; the oxygen partial pressure is 1 x
High frequency 2-pole sputtering iron 1000A at 10-4 Torr
A film thickness of . The sheet resistance was 300/mouth (specific resistance value was 300 French). Add 100 vanadium on top of this.
A. After gold was deposited using a lAm electron beam, a thermal head pattern with a four-line/side resolution was formed by selective etching. Next, aluminum oxide (AI2) was used as a protective film.
03) A seed layer was formed using sputtering. When this thermal head was subjected to the same acceleration test as in Example 1, the resistance change rate was within 2% up to 21 W/ground.
This example also gave much better results than the thermal head using tantalum nitride in the comparative example. (Example 5
) A tablet is made by pressing shelved niobium powder at 100 k9/h or more, and it is placed on a glazed ceramic substrate that has been thoroughly cleaned in advance, heated to 300 qo, evacuated to a vacuum level of 2xlo-6 Torr, and then dried air is blown with a needle. Vacuum level 5×10-6To while introducing with valve
It was deposited by electron beam to a thickness of 1000A at rr.

This area resistance is approximately 400/mouth (specific resistance value is approximately 400)
○Skin). Next, on top of this, 10A titanium and aluminum]. After vapor deposition with a 5mm electron beam and selective etching to form a pattern with a resolution of 4 lines/side, 1Am of silicon oxide (Sj02) and 101m of tantalum oxide (Ta205) were continuously sputtered. layered to create a thermal head. 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 0.20 (atomic ratio) of oxygen and niobium 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. East map Figure 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 niobium boride and oxygen. A thermal head characterized by comprising: 2 The oxygen content in the heating resistor is 0.0 of niobium.
05 (atomic ratio) or more. 3 The oxygen content in the heating resistor is 0.0 of niobium.
The thermal head according to claim 1, wherein the atomic ratio is 1 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 niobium 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 niobium boride. 11. The manufacturing method according to claim 8 or 9, wherein metal niobium and boron are arranged so as to be targeted at the same time. 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 niobium. 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 niobium 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. The manufacturing method according to claim 15 or 16, wherein electron beam evaporation is performed while heating the substrate at 200°C to 500°C.