JPS6038005B2 - 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 lanthanum 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 made of tantalum nitride, dichrome tin oxide, etc., thick 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 250~250.
It is particularly widely used because it has a relatively high value of 300 mm○ skin and has good controllability in production. However, tantalum nitride is rapidly oxidized at high temperatures of about 300 qC 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
A24) A wear-resistant layer was provided 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 particularly large before and after the mouth, the resistance is about 1000/0. In order to further increase the resistance value, methods such as trimming or thinning the film 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 multilayer wiring, the surface becomes extremely uneven and becomes susceptible to abrasion, resulting in major structural problems. In addition, the large current also causes disadvantages such as the need to increase the capacity of the heating power source, switching circuit, etc. 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 selection of specific resistance up to a high value. The heating resistor consists of oxygen.

In this heating resistor, shelved lanthanum 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 a shelf-shaped lanthanum 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, silicon oxide, magnesium oxide, aluminum oxide, tantalum oxide, or a multilayer structure made of a combination of these, 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 lanthanum shelving and oxygen can be manufactured by either sputtering or electron beam evaporation, and a method for manufacturing by sputtering involves using a lanthanum shelving target in a mixed atmosphere of argon and oxygen. There are methods of sputtering, methods of simultaneously targeting shelf elements and metallic lanthanum, and active sputtering methods of targeting only metallic lanthanum in an atmosphere containing argon, oxygen, and diborane.

When using shelved lanthanum as a target, for example, it can be used as a target by placing the shelved lanthanum in a powder state or pressed state on a quartz dish, etc., but it is possible to use it as a target by placing the shelving lanthanum in a powdered or pressed state on a quartz plate, etc. It is easier to control sputtering if a target is used.

In addition, when shelving elements and metal lanthanum are targeted at the same time, the shelving elements and metal lanthanum can be mixed, or one can be embedded in the other or placed on a part of the surface. In either case, 1×10-Tei on ~ 5 ×
It is best to carry out in a mixed atmosphere of argon and oxygen at 10-ITorr, preferably 1 x 10 - 1 x 10 -
ITorr is good.

In addition, when active sputtering is performed in a mixed atmosphere of argon, oxygen, and diporan using metallic lanthanum as a target, the total gas pressure is 1 × 10-orr to 5 × 10-I.
Tort, preferably lxlo-2rorr~5x10
-2Ton, the partial pressure of diborane is 1 to 1 of the full force in 3
0%, preferably 2-6%.

During any of the above sputtering steps, 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 0.005 to lanthanum.
or more.

If the oxygen content is too low, it will not be effective, and if it is too high, the control of resistivity will be affected and the heat resistance will also deteriorate, so a molybdenum content of 0.01 to 1.0 (atomic ratio) 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 200 to 5,000 F. When manufacturing a heating resistor by electron beam evaporation, tablets are made by pressing lanthanum powder at a pressure of about 100 k9/m or more, and the temperature is kept at a constant temperature in advance at a high vacuum of 1 x 10-4 tons 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 molybdenum by introducing a gas containing oxygen during electron beam evaporation using a needle valve or the like. The thin film heating resistor created in this way is made of shelved lanthanum and oxygen (contains impurities such as C.N.), 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° to 500° 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) 5-inch diameter shelf lantern B6 hot-pressed at 1100 qo [manufactured by Research, USA, purity 99.9]
%] target, a well-cleaned glazed alumina substrate with a glass thickness of 50 mm was heated to 300 oC under an argon pressure of 4 x 10-2 Ton and an oxygen pressure of 3 x 10-3 Ton in a mixed gas atmosphere. High frequency bipolar sputtering was performed.

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 1,200 French skin, and the area resistance was 1,200/mouth. The composition of this film was examined using an ion microanalyzer, and it was found that oxygen was 0.5% of lanthanum.
It contained 18 (atomic ratio). On top of this, titanium 10A,
Aluminum was applied by lrm 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. Further, as a protective layer, one layer of silicon oxide (Si02) and 10 layers of tantalum oxide (Ta205) were continuously sputtered on top of this 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-
1 under the conditions of 2Ton and nitrogen partial pressure of 1×1o-4Torr.
A thermal head B of a tantalum nitride thin film heating resistor with a thickness of 000Δ 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 meters of tantalum oxide (Ta205) were continuously sputtered to form a thermal head base. These thermal heads were subjected to an acceleration test using a rectangular wave of 8 hs at 50 Hz while increasing the power by IW/IW 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 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, and when a protective film is attached, very good heat resistance can be obtained. Ta. (Example 2) Using a 6-inch diameter shelved lanthanum (LaB) target hot-pressed at 130,000 yen, a thoroughly cleaned glazed alumina substrate with a glass thickness of 50 mm was heated at 200 yen.
Heating the substrate to 0.00 and increasing the argon pressure to 4
, high-frequency bipolar sputtering was performed in a mixed gas atmosphere with an oxygen pressure of 4×10 −3 Torr.

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. Specific resistance is 2100 Buddha Q skin,
The sheet resistance was 350Q/mouth. On top of this, 10△ vanadium and aluminum were attached using a 1〆m electron beam Aoi bonding.
A thermal head pattern with a separation of 4 lines/rib was formed by selective etching, and on top of this, 2 m of silicon oxide (SiO2) and 2 m of aluminum oxide (N) were added as a protective layer.
203) was continuously applied as a seed layer by sputtering for 5 meters 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 large number of brazed 1'4 inch diameter boron plates were placed on a 6 inch diameter metal lantern plate, and the surface area ratio was as follows:
A target with a shelf element ratio of approximately 1:2 was used.

500 thoroughly cleaned glazed ceramic substrates
The substrate was heated to R. 0.00 and the argon pressure: 3 x 1 orr oxygen pressure was 2 x 10-3 Ton. F. Sputtering was performed using two electrodes. 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 1040 French Q, and a sheet resistance of 1300/hole was obtained. After evaporating titanium at 10△ and aluminum using a lAm electron beam, a thermal head pattern having a resolution of 4 lines/skin was selectively etched. Next, 10 mm of magnesium oxide (Mg0) was deposited as a protective film 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 23W/fence.
Within a range of 100 to 100%, very good results were obtained compared to a thermal head using tantalum nitride.

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

400 thoroughly cleaned glazed ceramic substrates
The substrate was heated to zero, and active sputtering was performed in an atmosphere of a mixed gas of argon, diborane, and oxygen. The total pressure of argon diborane + oxygen is 3.5 x 10-2 Torr
, diborane partial pressure was 1.5 × 10-4 Torr, oxygen partial pressure was 1 × 10-4 Torr, and 10% by high-frequency bipolar sputtering.
A film thickness of 00A was applied. The sheet resistance was 500/mouth (specific resistance value was 500 peaks Q skin). After evaporating vanadium at 100 A and gold at 1 Am using an electron beam, selective etching was performed to form a thermal head pattern with a resolution of 4 lines/layer. Next, aluminum oxide (N203) loAm was formed as a protective film 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 22.5 W/shore. This example also gave much better results than the thermal head using tantalum nitride in the comparative example. (Example 5) Tablets were made by pressing powdered lanthanum at a pressure of 100 kg/c or more, and the tablets were placed on a glazed ceramic substrate that had been thoroughly cleaned in advance, heated to 30,000 yen, and vacuumed to a degree of vacuum of 2 x 10-5 Torr. After that, the vacuum level is 5 x 10-6 while introducing dry air with a needle valve.
Electron beam evaporation was performed to a thickness of 1000A at Torr.

The area resistance was about 700/mouth (specific resistance value was about 700 French c). Next, 10A of titanium and 1.5m of aluminum were deposited on top of this using an electron beam, and a pattern with a resolution of 4 lines/side was formed by selective etching. A thermal head was fabricated by continuously applying a seed layer of tantalum oxide (Ta205) by sputtering for 10 mm. When this thermal head was subjected to the same acceleration test as in Example 1,
Good results similar to those obtained with the thermal head were obtained.

When the composition of this waist was examined using an ion microanalyzer, it was found that it contained 0.15 (atomic ratio) of oxygen compared to lanthanum.

BRIEF DESCRIPTION OF THE DRAWINGS 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.

younger brother l figure 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 lanthanum boride and oxygen. A thermal head characterized by comprising: 2. Oxygen content in the heating resistor is 0.0 that of lanthanum.
005 (atomic ratio) or more. 3. Oxygen content in the heating resistor is 0.0 that of lanthanum.
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 lanthanum 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 lanthanum boride. 11. The manufacturing method according to claim 8 or 9, wherein lanthanum metal 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 lanthanum metal. 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 lanthanum 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.