JPS6016082B2 - thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head having a shelved niobium thin film and 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 nichrome, thick film heat generating resistors using silver-palladium and the like, and semiconductor heat generating resistors using CJ-con semiconductor. Among these, thermal heads using thin-film heating resistors have better thermal response, heat resistance, thermal shock resistance, long life, and reliability compared to thick heating resistors, semiconductor heating resistors, etc. It has characteristics such as high. Conventionally, tantalum nitride has been used as a thin film heating resistor because it has relatively excellent heat resistance, high reliability, and a specific resistance value of 250.
It is particularly widely used because it has a relatively high value of ~300r○ and 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
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 not small, and the result was still not fully satisfactory. In particular, as the demand for high-speed thermal heads has increased in recent years, it is necessary to shorten the energizing pulse of the head to color the thermal paper, which requires more power than before, and the heating resistor becomes even hotter. Lifespan becomes shorter. Therefore, there is a demand for a heating resistor with even higher heat resistance. The present invention aims to improve the above points and provide a thermal head having a thin film heating resistor that is resistant to oxidation and has a stable resistance value. The present invention includes a thermal head using niobium, a combination with a protective film covering the heating element, and a method for manufacturing the thin film heating resistor. 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 ceramic glass or grade ceramics. 2 is a thin film heating resistor made of shelved niobium.

Reference numeral 3 denotes an electrical conductor for supplying power to the thin film heating resistor, and is made of a good electrical 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, etc. produced by electron beam evaporation, sputtering, etc., or a multilayer structure consisting of a rough combination of these; This makes it possible to further extend the life of the thermal head. A thin film heating resistor made of shelved niobium can be manufactured by either electron beam evaporation or sputtering.For production by electron beam evaporation, about 100 ml of shelved niobium powder is used.
Press at a pressure of more than kg' to make tablets,
It can be deposited on a substrate that has been kept at a constant temperature in advance under a high degree of vacuum of 1×10-4 Ton or higher.

On the other hand, when manufacturing by sputtering, there are a method of using shelved niobium as a target, a method of using shelved niobium and metal niobium as targets at the same time, and a method of performing active sputtering using only metal niobium as a target. When using shelved niobium as a target, for example, it can be used as a target by placing the shelved niobium in a powdered or pressed state on a quartz plate, etc. It is easier to control sputtering by using a sintered target. In addition, if you want to target shelf elements and metal niobium at the same time, you can mix them together, or embed one in the other or place it on a part of the surface.
It can be carried out. In either case, 1×10-3To
It is best to carry out in an argon atmosphere of n~5×10-ITorr, preferably IXIO-2Ton~1xlo-IT
orr is good. In addition, when performing active sputtering, a single metal such as a metal niobium plate is used as a target in an atmosphere of a mixed gas of argon and diporane, and the gas pressure at that time is the total gas pressure of argon and diborane of 1 × 10 -
rr~5×10-ITorr, preferably 1×10-
At 汀orr~5×10-2Ton, Diporan is 1 of the total pressure.
-10%, preferably 2-6%. Also, during sputtering or electron beam evaporation,
Heating the substrate to 500 qo improves the adhesion of the shelved niobium to the substrate, and also has an effect on the stability of the film. Furthermore, after sputtering or electron beam evaporation, the resistance value can be controlled to the required value by performing heat treatment at a temperature of 200 to 650 0 in vacuum, air, or an atmosphere of argon gas, etc. It also increases stability when used as a fuel, which has an effect on longevity. When the heat treatment temperature is below 200°C, there is very little change in the resistance value, so a long heat treatment time is required.On the other hand, when the heat treatment temperature is above 650°C, the change in resistance value occurs suddenly, and it becomes impossible to use it with substrates such as glass. Due to usage restrictions or difficulty in control, the heat treatment temperature is preferably 200 to 650°C. The shelved niobium thermal head obtained in this way is stable and resistant to oxidation, and while the conventional thermal head using chambered tantalum had a maximum power consumption of 17 to 18 W/boil.
It can be used for power supply of up to 20-21.5W/fence. This is also suitable for a thermal head for high-speed printing, in which a large amount of power is applied to the heating resistor to raise the temperature to a high temperature. Furthermore, the specific resistance value of this shelved niobium thin film resistor can be selected from a wide range from 100 Buddha Q arc to 5 × 1 Pim○, so if you set it to a high resistance value, less current is required to generate heat. The electrode can be made thinner, which simplifies the manufacturing process, and it also has fewer irregularities, making it more resistant to wear. Furthermore, the amount of heat generated by the thin film heating resistor due to the influence of the resistance of the electrode portion can be ignored. Next, it will be explained based on an example. Example 1 Shelved niobium NbB (manufactured by Pentron, USA, 99.8%) hot-pressed at 130 pi on a glazed ceramic substrate that had been thoroughly cleaned in advance
Purity] as a target, high-frequency bipolar sputtering, total argon pressure of 5 x 1 on, substrate heating temperature of 2
A heating element with a thickness of 1000Δ was produced under the conditions of 00:00 and ○. This specific resistance value was about 200〆○㎇, and the area resistance at this time was about 200/mouth. On top of this, 10A titanium,
After aluminum was deposited with an electron beam of 1.5 mm, selective etching was performed to form thermal heads A, . was formed. Then the thermal heads A, . A thin layer of tantalum oxide is applied as a protective layer by electron beam evaporation.
Thermal head A, 2 has aluminum oxide vapor deposited on it, Thermal head A, 3 has aluminum oxide vapor deposited on it to a thickness of 8 mm, Thermal head A, 4 has aluminum oxide vapor deposited on it, 5 mm thick.
and thermal head A in which silicon oxide was deposited on a 1.5-layer thick layer and tantalum oxide was deposited in a two-layer structure with a 6-layer thick layer.
I have prepared 5. For comparison, tantalum was targeted by high-frequency bipolar reactive sputtering, and the total pressure of argon and nitrogen was 8 × 10-2 Torr, and the partial pressure of nitrogen was 1.
Thermal head B, . was created.

When this thin film was analyzed by X-ray diffraction, it was found to be Ta2N. Further, the specific resistance value was 240〆○ arc, and the area resistance value at this time was 240/mouth. Next, the thermal heads B, .
A tantalum oxide protective layer with a thickness of 6mm thick was provided by sputtering on B, 2, and a silicon oxide film with a thickness of 11.5mm was applied.
Further, a tantalum oxide film with a thickness of 6 rm was provided on it.
A sample B3 having a layered structure including a protective layer was prepared. For these prepared thermal heads, s with a pulse width of 6
Apply a repeated voltage of 50Hz and increase the supplied V power by 3
The resistance side rate, etc. when increasing IWatt/Iso at 0 minutes and performing a thigh test xlo.

(%) measurement results are shown in Figure 2.

Here, R is the resistance value before the test, and ΔR is the change in resistance value. Shelved niobium thin film heating resistors A, . are tantalum nitride thin film heating resistors B, . Approximately 1. Can supply electricity to Fang Moss. or,
By providing a protective layer, the power that can be combined per unit area is greatly improved.
, 2) Even when using only one protective layer of aluminum oxide (A, 3) and magnesium oxide (A, 4), the thermal head & 3 of the tantalum nitride thin film heating resistor with two protective layers is almost the same. Comparable results were obtained and were much better than thermal head B, 2, which was a tantalum nitride thin film heating resistor with one protective layer. Further, thermal heads A and 5, which have two protective layers of silicon oxide and tantalum oxide on shelved niobium, have been further improved.
This increase in the maximum power supply means that in the case of constant power driving, deterioration of the heating resistor due to heat generation phenomenon is reduced. Normally, the power supplied when transmitting thermal energy to thermal recording paper varies depending on the contact pressure, but is approximately 11 to 14 W/W.
In the case of a tantalum nitride thin film heating resistor, a two-layer protective layer such as a combination of silicon oxide and tantalum oxide is essential, whereas in the case of a niobium oxide thin film heating resistor, a tantalum nitride thin film heating resistor It can be seen that printing is sufficient with just one protective layer such as tantalum, aluminum oxide, magnesium oxide, etc., and that the life span is further extended when two protective layers are used. Example 2 The same thermal heads A, . Thermal head 2 is sputtered with tantalum oxide to a thickness of 6A as a protective layer, Thermal head 3 is sputtered with aluminum oxide to a thickness of 8mm, Thermal head 4 is sputtered with magnesium oxide to a thickness of 5Aw Thermal head A teeth were prepared by sputtering a two-layer protective layer of 1.5 μm of silicon oxide and then 6 μm of tantalum oxide.

These thermal heads were subjected to the same test as in Example 1 to measure the rate of change in resistance. As a result, the power limit per unit area at which the rate of resistance change rapidly increases is 2
The results were very good: 18.5w/fence for A23, 19.0w/ground for A23, 19.0w/ground for A pine, and 21.5w' for A turbidity. Better results were obtained when the protective layer was prepared by sputtering than by electron beam evaporation. Example 3 Shelved niobium NbZ [manufactured by Pentron, USA, purity 99.8%
] Powder was pressed at 100 k9/carp or more to make a tablet, and the tablet was placed on a glazed ceramic substrate that had been thoroughly cleaned in advance at a substrate heating rate of 30 mm and a vacuum level of 5 x 10 mm.
The film was deposited using an electron beam to a thickness of 800 Å.

This specific resistance value was approximately 0〃○〇, and the area resistance at this time was approximately 800/mouth. Next, after evaporating titanium at 10A and aluminum at 1.5R using an electron beam,
A putter with a resolution of 4 pieces/sail by selective etching.
The thermal heads C, . And so. These thermal heads C, . By electron beam evaporation as a protective film,
Thermal head C has tantalum oxide deposited to a thickness of 6mm, thermal head C3 has aluminum oxide deposited to a thickness of 8mm, thermal head C4 has magnesium oxide deposited to a thickness of 5mm, and silicon oxide 1. The same test as in Example 1 was conducted using a thermal head C, 5 in which a two-layer structure of 5 mm and 6 mm of tantalum oxide was deposited.
As a result, the limit values of power per unit area at which the resistance change rate increases rapidly are C, . Then 11.5w' is disgusting.
16.5W/K for C.2, 17.0W/K for C.3, C. 17.5w/ground for 4, 18.5w/ground for C,5
It was a pleasure.

The shelved niobium heating resistor produced by electron beam evaporation in this example was also much better than the tantalum nitride heating resistor. Example 4 Thermal heads C, . A protective layer was formed by sputtering on the thermal head C22 of tantalum oxide 6mm, thermal head C23 of aluminum oxide 8mm, thermal head C23 of magnesium oxide 5mm, silicon oxide 1.5mm and then oxidized. A thermal head C25 having a two-layer structure of tantalum of 6 cm was prepared.

These thermal heads were subjected to the same test as in Example 1, and the rate of change in resistance was measured.

As a result, the power limit values per unit area at which the rate of resistance change rapidly increases are 17.5 w/K for C Shigeru and 17.5 W/K for C2, respectively.
3 is 18.5w'co, C24 is 18.5w'co, C
In 25, it was 20w/. Example 5 A 6 inch diameter metal niobium plate was used as a target.

400q of thoroughly cleaned glazed ceramic plate
Active sputtering was performed in an argon/diborane mixed gas atmosphere by heating the substrate to 100 ℃. The pressure of argon + diborane is 3.5 x 10-orr, and the diborane partial pressure is 1
．． 700 by high frequency bipolar sputtering with 5×10-4 Tom
The film thickness was set to A. This specific resistance value was 1050〆○, and the area resistance at this time was 1500/mouth. After evaporating vanadium at 100A and gold using an LR skin electron beam, a thermal head pattern having a resolution of 4 lines/rib was formed by selective etching. Next, 10 μm of aluminum oxide (AI203) was deposited as a protective film by sputtering. When the same acceleration test as in Example 1 was performed on this thermal head W, the resistance change rate was within ±2% up to 18.0 W/rail. This example also gave much better results than the thermal head using tantalum nitride in the comparative example. Example 6 A target was used in which a large number of phosphorous 1/4 inch diameter boron plates were placed on a 6 inch diameter metal niobium plate so that the surface area ratio of metal niobium to shelf element was approximately 1:2. there was.

500 thoroughly cleaned glazed ceramic substrates
Heating the substrate to ℃ and argon pressure;
R. F. Sputtering was performed using two electrodes. Sputtering rate is 100A/
When sputtered for 8 minutes, a thin film heating resistor with a film thickness of 800 A, a specific resistance value of 960 μm, and an area resistance of 1200/hole was obtained. On top of this, 10A titanium,
After the aluminum was deposited using an LR electron beam, a thermal head pattern with a four-head suppression resolution was formed by selective etching. Next, as a protective film, tantalum oxide (Ta2
05>10 mountain surfaces were 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 17.5W/pine, which was much better than the thermal head using tantalum nitride. It was done. Example A shelved niobium powder was placed on a 75-inch diameter quartz dish to serve as a target.

High frequency bipolar sputtering was performed on the thoroughly cleaned glazed ceramic substrate at a substrate heating time of 200 pm and an argon partial pressure of 5 x 10-2 Ton. Sputter rate 100A'm
After 9 minutes of sputtering at in, the specific resistance value was 315rQ.
At this time, a shelved niobium thin film heating resistor with a sheet resistance value of 350/mouth was obtained. After evaporating titanium at 100A and gold at 1Aw using an electron beam, selective etching was performed to form a thermal head pattern with a resolution of 4 lines/rib.
Next, when heat treated in air at 550° C. for 1q hours, the resistance value of the heating resistor increased from 350/port to 950/port. Magnesium oxide (M) was sputtered as a protective film on this heating resistor to a thickness of 8 mm to obtain thermal heads ○ and 2. For comparison, thermal heads D, . We also prepared The third graph shows the resistance change rate measurement results when a rectangular wave with a ratio of 14W and 14W for 6 seconds at 50Hz was continuously applied to these thermal heads.
As shown in the figure.

The number of applied pulses is D, . The resistance change rate is about 10
%, whereas D,2 was about 7%, and the heat treatment reduced the resistance change and stabilized it.

Example 8 When the heat treatment in Example 7 was changed to 65,000 in Ar for 2 hours, the resistance changed from 350' to 310/in.

Here, 8r of magnesium oxide (Mg0) was sputtered as a protective film to obtain thermal heads D and 3.

Here, the same durability test as in Example 7 was conducted.

The results are shown in FIG. 3, and better results were obtained than in Example 7, and the resistance change rate was about 5% even when the number of pulse applications was 1×1.

[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. FIGS. 2 and 3 are characteristic diagrams showing the effects of the present invention. 1...
...Substrate, 2...Thin film heating resistor, 3...
...Electric conductor, 4...Protective layer. Back - Figure 2 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. A thermal head featuring: 2. The thermal head according to claim 1, wherein the heating resistor is covered with a silicon oxide thin film. 3 Claim 1 having a tantalum oxide protective film
The thermal head according to item 1 or 2. 4. The thermal head according to claim 1 or 2, which has a protective film of aluminum oxide. 5. The thermal head according to claim 1 or 2, which has a protective film of magnesium oxide. 6. A method for manufacturing a thermal head, comprising manufacturing a boride thin film on a substrate by electron beam evaporation. 7. The manufacturing method according to claim 6, wherein electron beam evaporation is performed while heating the substrate at 200°C to 500°C. 8. The manufacturing method according to claim 6 or 7, wherein heat treatment is performed at 200°C to 650°C after electron beam evaporation. 9. A method for manufacturing a thermal head, comprising manufacturing a heating resistor of a thin niobium boride film on a substrate by sputtering. 10. The manufacturing method according to claim 9, wherein the sputtering target is hot-pressed niobium boride. 11. The manufacturing method according to claim 9, in which active sputtering is performed in a mixed gas atmosphere of argon and diborane using niobium metal as a target. 12. The manufacturing method according to claim 9, wherein metal niobium and boron are arranged so as to be targets at the same time. 13 1×10^-^3Torr~5×10^-^1T
The manufacturing method according to claim 9, 10, or 12, wherein the puttering is performed in an argon atmosphere. 14. The manufacturing method according to claims 9 to 13, wherein sputtering is performed while heating the substrate at 200°C to 500°C. 15. The manufacturing method according to claims 9 to 14, wherein heat treatment is performed at 200°C to 650°C after sputtering.