JPS6038007B2 - 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 titanium 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 electrical 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 and contacting the recording medium so as to obtain the necessary heat pattern according to the information to be recorded. It is. 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 heating resistors, semiconductor heating resistors, etc. It has the following characteristics. Conventionally, tantalum nitride has been used as a thin film heating resistor, which has excellent heat resistance, high reliability, and has a specific resistance value of 250 to 300 rQ.
It is particularly widely used because it has a relatively high value of c and good manufacturing controllability. However, tantalum nitride has about 3000
At high temperatures of 0 or higher, 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. Particularly in recent years, as the demand for high-range thermal heads has been increasing, it is necessary to shorten the duration of 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 opening, it will only be about the same as the looQ opening.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 feature lies in the heating resistor made of titanium shelving and oxygen.

In this heating resistor, shelved titanium 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 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 titanium shelving 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, 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 titanium shelved and oxygen can be manufactured by either sputtering or electron beam deposition. There are methods such as sputtering a target, a method using rigidity and titanium metal as targets at the same time, and a method using active sputtering using only titanium metal as a target in an atmosphere containing argon, oxygen, and diborane.

When titanium shelving is used as a target, it can be used as a target by depositing the titanium shelving in powder or pressed form on a quartz plate, for example, but it is possible to use it as a target by placing titanium shelving 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 using shelf elements and metallic titanium as targets at the same time, this can be done by mixing the shelf elements and metallic titanium, or by embedding one in the other or arranging 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-torr to 1 x 10-I
Torr is good.

In addition, when active sputtering is performed using metallic titanium as a target in a mixed atmosphere of argon, oxygen, and diborane, the total gas pressure is 1 × 10-2 TOrr to 5 × 10-I
Ton, preferably 1×10-2 Torr to 5×10-
2Ton, in which the partial pressure of diborane is 1 to 1 of the total pressure.
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 0.00% to that of molybdenum.
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 specific resistance and the heat resistance will deteriorate, so 0.01 to 1.0 (atomic ratio) of titanium is appropriate, and 0.05 ~0.6 is more preferable,
0.1-0.3 is most preferred. The specific resistance value of the heat generating resistor created in this way is 200 cm~5000 cm
You can select up to . When manufacturing a heating resistor by electron beam evaporation, approximately 100 k9/g of shelved titanium powder is used.
Press with more than average pressure to make tablets 1×10-
It can be deposited on a substrate that is kept at a constant temperature in advance under a high degree of vacuum of 4 tons or more. 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 into the electron beam deposition using a needle valve or the like. The thin film heating resistor created in this way is made of titanium shelving 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.

Furthermore, 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, allowing freedom in designing electrode patterns such as matrix wiring. Furthermore, by heating the substrate to 20,000 to 500oC 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) Shelf titanium TiB2 with a diameter of 5 inches hot pressed at 1100 qo [manufactured by Sanyiwa Chemical Co., Ltd., Ti68.70%, B
30.72%], a thoroughly cleaned glazed alumina substrate with a glass thickness of 50 m is
Increase the argon pressure to 4×1 while heating the substrate to
, high-frequency bipolar sputtering was performed in a mixed gas atmosphere at an oxygen pressure of 3×10-3 Ton.

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 looOA○, and the area resistance was 1000/mouth. When we investigated the composition of this waist using an ion microanalyzer, we found that the oxygen content was 0.2 that of titanium.
It contained 6 (atomic ratio). On top of this, titanium 10A and aluminum were deposited by lAm electron beam evaporation, and a thermal head pattern having a resolution of 4 lines/side was formed by selective etching, and this was designated as thermal head A. Furthermore, silicon oxide (Si02) is added as a protective layer on top of this.
, tantalum oxide (Ta205) was continuously deposited by sputtering for 10 rms to form a thermal head. For comparison,
Targeting tantalum by high-frequency bipolar reactive sputtering, the total pressure of argon and nitrogen is 8×10-2.
Tom, 10 under the condition that the nitrogen partial pressure is 1 x 1o-4 Torr.
A thermal head B of a tantalum nitride thin film heating resistor with a thickness of 00A was fabricated.

This tantalum nitride thin film heating resistor has a specific resistance of 260mm.
The area resistance was 260/mouth. Thermal head B
, silicon oxide (Si02
) and 10 m of tantalum oxide (Ta205) were continuously sputtered into a bran layer to form a thermal head &. An acceleration test was performed on these thermal heads while increasing the power of the AHS rectangular wave at 50 Hz by IW/fence every 3 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 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 to practical use without a protective film, and when a protective film is attached, very good heat resistance is obtained. (Example 2) Using a 6-inch diameter shelved titanium (CrB2) target hot-pressed at 1300 oo, a thoroughly cleaned glazed alumina substrate with a glass thickness of 50 mm was heated to 200 mm.
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 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 600 A was obtained. Specific resistance is 1900 mountain Q skin,
The sheet resistance was 310Q/mouth. On top of this, 10△ vanadium and 1△ aluminum were applied by electron beam evaporation.
A thermal head pattern with a separation of 4 wires/sail was formed by selective etching, and on top of this, 2 mm of silicon oxide (Si02) and 2 mm of aluminum oxide (N) were added as a protective layer.
203) was continuously laminated by sputtering to form 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 in which a large number of sintered 1/4 inch diameter boron plates were placed on a 6 inch metal titanium plate so that the surface area ratio of metal titanium to shelf element was approximately 1:2. was used.

500 thoroughly cleaned glazed ceramic substrates
The substrate was heated to R.C. under an argon pressure of 3×10-2 Tom and an oxygen pressure of 2×10-3 Ton. F. It sputtered on two poles. When sputtering was carried out for 8 minutes at a sputtering rate of 100 A/min, a thin film heating resistor having a film thickness of 800 Δ, a specific resistance value of 920 AQ, and a sheet resistance of 1150 N was obtained. After evaporating titanium and aluminum using an IWM electron beam, a thermal head pattern with a resolution of 4 lines per side was formed by selective etching. Next, 10 m 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 22W/ground.
Within a range of 100 to 100%, very good results were obtained compared to a thermal head using tantalum nitride.

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

Thoroughly cleaned glazed ceramic substrate
The substrate was heated to ℃ and active sputtering was performed in an atmosphere of a mixture of alcon, diborane, oxygen, and a mixed gas. The total pressure of argon + diborane + oxygen is 3.5 x 10-2 Torr
, diborane partial pressure is 1.5×10-4 Torr, oxygen partial pressure is 1×104 Ton, and 1000△ by high-frequency bipolar sputtering.
A film thickness of . The sheet resistance was 430/mouth specific resistance was 430rQ (skin). 10 vanadium on top of this
After evaporating gold with a lAm electron beam, a thermal head pattern with a four-line/side resolution was formed by selective etching. Next, aluminum oxide (mountain 2) was applied as a protective film.
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 within 2% up to 22.5 W/min. This example also gave much better results than the thermal head using tantalum nitride in the comparative example. (Example 5) 100k9 shelved titanium powder
A tablet is made by pressing it with a pressure higher than that of carp, and it is placed on a glazed ceramic substrate that has been thoroughly cleaned in advance. The substrate is heated to 30,000 psi and evacuated to a degree of vacuum of 2 x 10-6 tons, and then vacuumed while introducing dry air with a needle valve. It was deposited by electron beam to a thickness of 1000A at 5×10-6Ton.

The area resistance was about 580/mouth (specific resistance value was about 580 fcc). Next, titanium (10△) and aluminum (1.5 mm) were deposited using an electron beam, and then a pattern with a resolution of 4 lines/side was formed by selective etching, and then silicon oxide (Si02) was deposited at 1 mm (1 mm). A thermal head was fabricated by continuously sputtering 10 meters of tantalum oxide (Ta205). When this thermal head was subjected to the same acceleration test as in Example 1,
Good results were obtained that were similar to those of the thermal head.

When the composition of this film was examined using an ion microanalyzer, it was found that it contained 0.18 (atomic ratio) of oxygen to chromium.

[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. Little brother l 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 composed of titanium boride and oxygen. A thermal head characterized by comprising: 2 The oxygen content in the heating resistor is 0.0 that of titanium.
05 (atomic ratio) or more. 3 Oxygen content in the heating resistor is 0.0 of titanium.
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 titanium 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 titanium boride. 11. The manufacturing method according to claim 8 or 9, in which titanium metal and boron are arranged so as to be targets 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 titanium 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 titanium 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.