JPS62202756A - Thin film type thermal head - Google Patents

Abstract

PURPOSE:To obtain a thin film type thermal head of high heat resistance and resistivity having a long life and an adjustable temperature coefficient, by using a heat resistor containing a high-melting metal, a silicon, a boron, an oxygen, and a nitrogen, as main ingredients. CONSTITUTION:A glaze layer 2 is formed on the surface of a glazed ceramic substrate 1. On the glaze layer 2 a thin film resistance heating element 3 is formed by a sputtering process, and thereon an electric power supplying electrode 4 (Ni, Cr, and Al, etc., especially Al) is formed by deposition or sputtering, and finally thereon a wear resistant protective film 6 (e.g. BP series, Si-O series, Al-Si-O series, etc.) is formed by a sputtering process, etc. The heating resistor 3 is a nitrogen-oxide containing a silicon, a boron, and a high- melting metal M (at east one from among Ti, Mo, W, Hf, Ni, V, Zr, La, Cr, Ta, Fe, and Co). In a thermal head using the above heating resistor, the value of resistance is not varied even with the application of many heat pulses, the heat resistance is enhanced, and, additionally, the values of resistivity and resistance temperature coefficient can be desirably obtained because of the variation to a great extent according to the content of the high-melting metal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thin film thermal head, and more particularly to a thin film thermal head having an improved thin film heating resistor.

[Prior Art and its Problems] Thin-film thermal heads using thin-film heating resistors are widely used as print heads in computers, word processors, facsimile machines, and the like. The thermal head has a large number of resistive heating element dots arranged, and selectively energizes them to generate heat in a desired pattern or character shape, thereby thermally transferring the color material of the printing ribbon to the paper surface. Various resistance heating elements are known or used, but the most commonly used material is Ni.
-Cr 1-a2N, Cr-5i02, Cr-3i, etc.

Although these have excellent properties as resistance heating elements for thermal heads, they also have various drawbacks. Metal-based heating resistors such as alloys have poor heat resistance and oxidation resistance, and when the energy necessary for printing is repeatedly applied, the heat generation causes oxidation of the heating resistor, leading to an increase in resistance value and causing printing problems. This leads to deterioration of characteristics.

In addition, these metal heating resistors undergo large thermal expansion and contraction when placed under rapid thermal cycles due to heat pulses caused by repeated energization, creating large stress between the underlying substrate and the surface wear-resistant protective film. This causes cracks. on the other hand,
In the case of oxides and nitrides such as Ta5i02, their thermal conductivity is low, so they lack heat uniformity within the heating element, resulting in a decrease in printing quality.

In addition, metal-based heating resistors have a small specific resistivity, and even compound-based heating resistors listed in L have a small specific resistance (200 to 300 μΩcm for a 2N, approximately 2000 μΩcm for a 3i02), making it suitable for thermal heads. In order to obtain the required sheet resistance of 1 (around 7 holes), several tens of thin film heating resistors must be realized, and it is difficult to stably manufacture them.The typical manufacturing method is Although well-known semiconductor process technologies such as sputtering, ion blating, and CVD methods are used, process control is difficult when the film thickness is approximately 1,000 layers.In addition, the temperature coefficient of resistance of these heating element materials varies with the component ratio. It is relatively insensitive and difficult to control to a desired value.Furthermore, in metal systems, a reaction occurs between the heating element and the power supply electrode, resulting in defects such as fluctuations in the resistance value of the heating resistor and disconnection. cause the occurrence.

[Objective of the Invention] Therefore, the object of the present invention is to provide a material with high heat resistance, long life, and
It is an object of the present invention to provide a thin film type thermal head using a thin film heating resistor having a large specific resistivity and an adjustable temperature coefficient.

[Summary of the Invention] The present invention is characterized in that a thin film heating resistor contains a high melting point metal, silicon, boron, oxygen, and nitrogen as main components. That is, )1-3i-8-0-
Covered with N-based heating resistor. Here H is a high melting point metal, Ti,
Ha, w 1Hf, Ni, V, Zr, La,
Ta.

At least one selected from Fe, Co and C.

Due to the presence of the high melting point metal, the resistivity of the heating element does not change over a long period of time even with repeated heat pulses, resulting in a stable thermal head. Also, unlike metal-based materials, since it is an oxy-nitride, thermal expansion and contraction are small, and large internal stress due to the difference in thermal expansion coefficient between the upper and lower layers does not occur, and cracks do not occur.

Increasing the concentration of metal, boron nitride, and silicon improves thermal conductivity and improves thermal uniformity, and the presence of sufficient nitrogen stabilizes the properties without fear of oxidation over time. Furthermore, since the specific resistivity and temperature coefficient of resistance change greatly depending on the content of high-melting point metals, controlling the content increases the control range of the characteristics of the thermal head.
It is also possible to easily design a heating element resistance such as μΩcm.

With such a high resistivity, the thickness of the heating element thin film is preferably around 1000, which facilitates film formation.

[Detailed Description of the Invention] The outline of the structure of the thin film type thermal head of the present invention is shown in FIG. In the figure, 1 is a glazed ceramic substrate, on the surface of which a glazed layer 2 is formed. The glaze layer 2 is an oxide corresponding to a porcelain glaze and contains silicon and aluminum oxides, and more preferably also contains the same high melting point metal used in the heating resistor. A thin film resistance heating element 3 of the present invention is formed on the glaze layer 2 by, for example, a well-known sputtering method, and a power supply electrode (Ni, C, etc., in particular) 4 is formed by vapor deposition or sputtering. Finally, a known wear-resistant protective film (
For example, BP series, 5i-0 series, Aj-3i-0 series, etc.)
6 is formed by a sputtering method or the like.

The heating resistor 3 is made of silicon, boron, and high melting point gold JFmM (1,) to, W, In1, V, according to the present invention.
, lr.

It is a nitride-oxide containing at least one of La, Cr, Ta, Fe, and Co). What is particularly important in the present invention is the inclusion of boron. The action of this high melting point metal differs depending on the type, but regardless of whether it is used alone or in any combination, the resistivity and temperature coefficient of resistance of the heating resistor are 107 to 102 μΩcm and -15OO to +so, respectively.
It fluctuates widely in the oppm/'C range. Therefore, by selecting a specific refractory metal content, a heating element with a desired resistivity and temperature coefficient can be designed.

For example, if one with a resistivity of 104 μΩcm is selected, the film thickness can be 1000 Å or more. Generally, high melting point metals are 10~
It can be selected within a range of 60 wt%. This point will be specifically illustrated in Examples. B, Si, 0, and N form a heat-resistant and oxidation-resistant substance, and by changing their ratio, the resistivity can be changed while maintaining heat resistance. For example Sl o, 34B0.06
0.15 NO, 33 Resistivity >>1°7μΩcm-
Temperature coefficient < -1500pl)Itl/℃, but when the content of high melting point metal M is 10wt% or more, it is 107μ
It is possible to obtain Ωcm or less and -100ppm/'C or more.

) 1. If the glaze layer 2 containing at least two of Si, B, 0, and N is selected, the heating resistor of the present invention will fit well on the surface of the underlying substrate, and the difference in coefficient of thermal expansion will be reduced, which is preferable. . It would be even more convenient if the same applies to the wear-resistant protective layer 6.

The heating resistor of the present invention can be manufactured particularly by a sputtering method. For example, solid powder having a desired composition ratio is produced in advance, it is compressed into pellets, and this is used as a target and Ar is used as a sputtering gas, and if necessary, 02 gas, N2 gas, etc. Ions are bombarded with a target, and the released ions or atoms are deposited on a substrate. The film composition can be adjusted by changing the pellet composition and sputtering conditions.

Example composition H0x ”' 0.34 80.06 00.15
1-6mT targeting No. 33 pet
Using orr Ar as sputtering gas, the target
A heating resistor having the above composition was manufactured by adjusting the conditions of substrate distance 60 mm, RF power 1 to 10 W/Cm', and substrate temperature 200 to 400°C, and further A! A thermal head was created by sequentially depositing electrodes and a protective film. Note that the substrate surface layer and the protective layer contained a small amount of No in addition to Si and 8. The following tests were conducted on the obtained thermal head.

Pulse width 0.3 msec for sample x = 0.12,
Figure 2 shows the rate of change in resistance when a heat pulse with a period of 1 msec was applied. Further, the resistivity and temperature coefficient of resistance depending on the MO content are shown in FIG. In addition, as control samples, a conventional D2N heating resistor A and a Zr-3i heating resistor C were used.
The results of the heat resistance pulse test are also shown in Figure 2.

B in FIG. 2 shows a thermal head using a heating resistor according to the present invention.

[Operation and Effect] As can be seen from Fig. 2, the present invention) to-3i-8-0
The thermal head using the -N non-heat generating resistor B has good heat resistance as the resistance value does not change even if a large number of heat pulses are applied.

When a certain number of heat pulses are exceeded in the conventional heating resistors A (Za2N) and C (Zr-3i), the change in resistance becomes large.

As can be seen from FIG. 3, the resistivity and temperature coefficient of resistance of the heating resistor of the present invention vary greatly depending on the content of the high melting point metal. Therefore, these values can be designed to desired values by adjusting the content of the high melting point metal.

The improvement in heat resistance is thought to be due to the uniformity of the temperature distribution within the plane of the heating element and the reduction in the coefficient of thermal expansion.

Also, on the surface layer of the underlying substrate and/or the wear-resistant protective layer)
If a material containing O, Si, B, O, and t4 is used, the mutual compatibility will be improved, the adhesion will be improved, the material will be resistant to thermal shock, etc., and the occurrence of cracks, peeling, etc. will be suppressed. Further, the heating resistor of the present invention has excellent chemical resistance and is hardly affected by alkali or moisture.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of a thermal head, FIG. 2 is a graph showing a heat resistance test of a thermal head using the heating resistor of the present invention and a conventional example, and FIG. 3 is a graph showing heat generation in the thermal head of the present invention. It is a graph showing the relationship between a high melting point metal contained in a resistor, resistivity, and resistance temperature coefficient.

Claims (1)

[Scope of Claims] 1. A heating resistor thin film containing a high melting point metal, silicon, boron, oxygen, and nitrogen as main components is provided on a thermal base substrate, and a wear-resistant protective film is formed on its surface, Furthermore, a thin film type thermal head has a power supply electrode connected to the resistor. 2. High melting point metal is Ti, Mo, W, Hf, Ni, V, Z
2. The thermal head according to item 1, which is selected from the group consisting of r, La, Cr, Ta, Fe, and Co. 3. The thermal head according to item 1 or 2, wherein the surface layer of the base substrate is a glaze containing at least three of silicon, boron, O, N, and a high melting point metal. 4. The thermal head according to any one of items 1 to 3, wherein the wear-resistant protective film contains at least two of silicon, boron, O, N, and a high melting point metal. 5. The thermal head according to any one of items 1 to 4 above, wherein the power supply electrode is an Al single layer.