JPS61137302A - Thin film type thermal head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thin film heating resistor for a thin film thermal head used for thermal recording printing.

BACKGROUND TECHNOLOGY In general, a thermal head used for thermal print recording is provided with a plurality of heating resistors and an electrode for supplying power to the heating resistors on an insulating substrate. By supplying electric power, Joule heat is generated, thereby performing printing and recording.

As the heating resistor used for these, thin film heating resistors have good thermal response, can achieve high resolution, have excellent heat resistance,
It is the best in terms of long life and high reliability.

As a conventional thin film resistor, for example, Japanese Patent Application Laid-Open No. 52-143
As stated in No. 841, Ta-E3i alloy etc. have excellent heat resistance.

However, in order to achieve high-speed thermal printing recording using recent thermal heads, it is necessary to perform printing using short printing pulses of several S + It is necessary to generate a temperature of 400°C or more. In addition, high power
Unless the resistance value of the thin film heating resistor is increased, the current will inevitably increase, resulting in the following two problems. One is that the resistance value of the electrode that supplies power to the thin film heating resistor cannot be ignored with respect to the resistance value of the thin film heating resistor, so the difference in the length of the electrode causes the difference in the resistance of each thin film heating resistor. The amount of heat generated is different, causing a density difference in the recorded pattern, and especially when the resolution is increased, power consumption in the electrode becomes a problem. In order to avoid this, it is conceivable to make the thickness of the electrode extremely large, but this would cause a major structural inconvenience. Another problem is that the capacity of the drive system, such as the heating power source and the switching circuit, must be increased.

From the above points, a thin film heating resistor must have two minimum requirements: high temperature stability and the ability to realize a high resistance value.

From these points, considering the Ta-8l alloy, the T
A-8T alloy has a relatively stable heat resistance region as small as 200 to 260 μΩ-1 in specific resistance. Therefore, if you want to obtain a large resistance value, for example, L/W = 2 (L is a The dot length of the heating resistor (W is the dot width) is 500
In order to obtain a resistance value of Ω (recent technological trends require a higher resistance value), the film thickness is extremely thin, around 100A, and control during manufacturing is extremely difficult, and the film quality is It also becomes unstable. To avoid this, the Ta
It is possible to increase the resistance value by increasing the thickness of the -3i alloy, forming a pattern in a meandering shape, etc., and increasing the length of the pattern, but when achieving high resolution, this method is difficult to achieve due to manufacturing issues. Extremely difficult.

Furthermore, the Ta-8t alloy does not have sufficient heat resistance during short pulse width driving, and therefore the Ta-3L alloy is sufficient in terms of the high speed and high heat resistance required for thermal heads. It wasn't.

Problems to be Solved by the Invention As mentioned above, the Ta-8L alloy, which is the material for the thin film heating resistor of the conventional thermal head, does not have sufficient characteristics to make the thermal head faster and more heat resistant. does not have. From this point of view, the present invention aims to increase the speed of the thermal head,
The object of the present invention is to provide a thin-film thermal head equipped with a thin-film heating resistor that has high resistance, high specific resistance, excellent high-temperature stability, and high heat resistance necessary for high heat resistance. In particular, a thin film type thermal head is constructed using titanium carbide as the transition metal carbide.

Function The titanium carbide in the above structure is hard, has a high melting point, and is chemically stable, but has a specific resistance of 200 μΩ.
-α is not necessarily large, so by mixing it with silicon and silicon oxide, a thin film heating resistor with high specific resistance, excellent high temperature stability, high heat resistance, and small resistance fluctuation can be created. A thin film type thermal head can be constructed.

Embodiment FIG. 1 shows the basic configuration of a thin film type thermal head according to the present invention. A thin film heating resistor 2 made of a transition metal carbide, silicon, or silicon oxide is formed on an electrically insulating substrate 1 by a thin film forming technique such as sputtering, and a heat generating resistor 2 made of a transition metal carbide, silicon, or silicon oxide is formed on the electrically insulating substrate 1. After forming the electrode 3, a pattern is formed using photolithography technology, and a protective film 4 made of an insulating material, a semiconductor, etc. (exists to prevent contact wear). In this example, titanium carbide using titanium carbide and silicon are used as the transition metal carbide.

A thin film heating resistor made of silicon oxide will be described. The thin film heating resistor made of titanium carbide, silicon, or silicon oxide (hereinafter abbreviated as TiC-8l-8i02) can be easily formed using, for example, conventional sputtering technology. FIG. 2 shows the sputtering target used in this example as an example of the sputtering target.

51076 on the 160φ TiC target S, which is approximately 2 of the occupied area of the 5i02 plate 6 considering the sputtering rate.
A St 2 plate 7 having twice the occupied area is placed, and the ratio of the combined area of the SiO□ plate 6 and the 81 plate 7 to the area of the Tic target 60 is 20% and 30%, respectively.

1.5X10-2T by Ar gas instead of ao%
orr, RF power 400W, substrate temperature 5001? : High frequency sputtering was performed to form the Tic-3L-8io2 thin film heating resistor on the electrically insulating substrate 1. FIG. 3 shows the Tic obtained by the above method.
-3i-8in2 The specific resistance and temperature coefficient of resistance of the thin film heating resistor are shown. On the horizontal axis, S! What is the target area ratio of the 02 plate 6 and the Si plate 7? ll (However, SiO□
(The area occupied by the plate 6 is approximately half that of the Si plate 7) The vertical axis shows the specific resistance and the temperature coefficient of resistance.

Also, straight line 8. Straight line 9 represents the temperature coefficient of resistance and specific resistance immediately after sputtering at a substrate temperature of SOO°C, and straight line 10. The straight lines 11 each have a diameter of 660 after sputtering.
These are the temperature coefficient of resistance and specific resistance after vacuum heat treatment at ℃ for 2 hours. As is clear from the figure, SOO~660C
There is almost no variation in resistivity between 20 to 30%, the variation in temperature coefficient of resistance is small, and it has high temperature stability.
00μΩ-α, resistance temperature coefficient is 11oO~-160p
pw'deq is about 10 times the resistivity of conventional Ta-3i alloy, and the temperature coefficient of resistance is slightly higher than Ta-3i alloy.
The properties of the 3i alloy are significantly improved in the positive direction, and therefore compared to the Ta-5i alloy. By the way, after forming a thermal head with the structure shown in Figure 1, continuous pulses were applied to it with a pulse width of 1 m5 ec and a pulse period of 10 m8110, and when the pulse was applied 8 x 104 times,
The applied power (singing) (referred to as rupture power) that gives a resistance value fluctuation of +10% is shown for the TiC-5t-3iO2 thin film heating resistor and the Ta-3i alloy thin film heating resistor.
It is as shown in Table 1 below.

From the table, it is clear that the TiC-3i-3in2 thin film heating resistor is significantly improved in terms of heat resistance compared to the Ta-8i alloy thin film heating resistor.

In addition, Fig. 4 shows an example of resistance change characteristics with a pulse width of 1
m5ec pulse period 20 maec applied power 64W/
It shows the resistance change rate when continuous pulses are applied at j. The horizontal axis represents the number of pulse applications, and the vertical axis:
Represents the rate of change in resistance.

Curve 12 is Ta-8i alloy thin film heating resistor 9 curve 13
are the resistance change characteristics of the T i C-8i-3i02 thin film heating resistor of the present invention, and for comparison, curve 14 is made of titanium carbide and silicon oxide (hereinafter referred to as TiC-8i
(referred to as n2) shows the resistance change characteristics of the #film heating resistor,
Curve 16 is composed of titanium carbide and silicon (hereinafter referred to as TiC3
(referred to as i) shows the resistance change characteristics of the thin film heating resistor.

From the same figure, the Ta-5i alloy thin film heating resistor shows a sudden change in resistance in the negative direction with a relatively fast number of pulses, and this causes excessive power input (due to grain growth of Ta-3t, etc.). 17) K
In contrast, the T i C-8i-8io2 thin film resistor.

T50-3t02 Thin film heating resistor, Tic-3i
All of the thin film heating resistors can be said to have significantly improved resistance change characteristics and good heat resistance, but among them, the TIC-3i-S i02 thin film heating resistor has the best characteristics. I can say it. This can be explained as follows.

From curve 142 and curve 16, the resistance change of the T1C-8i02 thin film heating resistor is displaced in the negative direction (the annealing effect is considered to be dominant), and the resistance change of the Tic-3i thin film heating resistor is displaced in the positive direction. (It is thought that oxidation or thermal aggregation of St is dominant) Therefore, the TiC-8i-3in2 thin film heating resistor is
By mixing IC3i and S102 in an appropriate ratio, the properties of both Tic-3L and TiC-3iOθ cancel each other out, resulting in good properties.

In this way, the thin film heating resistor composed of titanium carbide, silicon, and silicon oxide has high resistivity and excellent high temperature stability.
Because it has high heat resistance and small resistance fluctuations, thin-film thermal heads using it can easily accommodate higher speeds and higher heat resistance. In this example, titanium carbide is used as the transition metal carbide, but other transition metal carbides having a high melting point such as zirconium carbide and nitride carbide may also be used.

Even if vanadium carbide, niobium carbide, tantalum carbide, molybdenum carbide, tungsten carbide, etc. are used,
These include silicon because they are hard, have high temperature stability, and are chemically stable.

A similar effect can be obtained by appropriately mixing silicon oxide to form a thin film heating resistor.

Effects of the Invention As described above, the present invention provides a thin film heat generating device which has high resistivity, high thermal stability, and small resistance fluctuation, and is composed of an appropriate mixture of transition metal carbide, silicon, and silicon oxide. This is a thin film type thermal head equipped with a resistor, which makes it possible to easily support higher speed and higher heat resistance of the thermal head, and its industrial value is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a basic structural diagram of a thin film type thermal head according to the present invention, and FIGS. FIG. 7 is a shape diagram, a resistivity and resistance temperature coefficient characteristic diagram, and a resistance change rate characteristic diagram. 2...Transition metal carbide and silicon in the present invention. Thin film heating resistor made of silicon oxide. Name of agent: Patent attorney Toshio Nakao and one other person
...J-sha...! &4nL Shasaka Figure 1? 10. Thin J! Capsule 9? ! , string 3
...7t Yang 4... Izuki-j! λ1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A thin-film thermal head characterized by comprising a thin-film heating resistor made of a transition metal carbide, silicon, and silicon oxide. (2) The thin film type thermal head according to claim 1, wherein the transition metal carbide is a titanium carbide.