JPS59169872A - Thermal head and manufacture thereof - Google Patents

Abstract

PURPOSE:To eliminate the need for a protecting film against fluoric acid and simplify the construction of a thermal head, by forming a thermal head in such a manner that a tantalum resistor is directly formed on a substrate coated with glass or quartz, and a wiring conductor is connected to the resistor. CONSTITUTION:On an alumina substrate 1 having a coating layer 2 of glass or quartz, a tantalum resistor thin film 4 and a wiring conductor thin film 5 are formed. Thereafter, a photoresist pattern is formed by a photoetching using an ordinary photoresist, whereby the wiring conductor 5 is etched into a stripe shape. The tantalum resistor thin film 4 is etched by a plasma etching using a gas containing fluorine atoms. The thickness of the coating layer 2 of glass or quartz is generally 20-100mum. Materials for the tantalum resistor thin film 4 include Ta-SiO2 cermet and Ta-Si cermet.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head for heat-sensitive recording and a method for manufacturing the same, and particularly relates to a thermal head using a resistor material containing tantalum atoms as a heating resistor material employed in a thin film thermal head. It concerns the structure of and its manufacturing method.

Conventionally, tantalum compounds and tantalum mixtures, which have excellent heat resistance, power resistance, etc., have been used as resistor materials for thin film thermal heads. This heat generating resistor thin film is formed on a glass or alumina substrate coated with glass or quartz (hereinafter referred to as glazed) using a vacuum evaporation method or a sputtering method, and is formed into the desired shape using an ordinary photolithographic etching method. formed into a pattern. Etching of tantalum resistor thin films has been carried out using a solution containing hydrofluoric acid. At this time, since hydrofluoric acid also corrodes the glaze (glass or quartz) of the glass or glazed alumina substrate, the fluoride The entire protective film for the fluoride cable acid protection IL was made of a thin film material that would not be corroded by hydrogen acid.

For example, a conventionally used thermal head will be explained step by step based on the drawings.

FIG. 1 is a perspective view showing the state of a conventional thermal head after forming a wiring conductor thin film. In the figure, ftl is an alumina substrate, and (2) is a glaze layer formed on the lamp alumina substrate. +11 and (2) are called glazed alumina substrates. The thickness of the glaze layer (2) is about 20 to 10°pm,
It has the function of controlling the heat generated by the heating resistor and the role of making the substrate surface smooth. The thinner the glaze layer (2) is, the better the printing speed of the thermal head is. A substrate protection film for preventing hydrofluoric acid is formed on this glazed alumina substrate. Tantalum oxide is used as the hydrofluoric acid prevention film (3). This tantalum oxide film, for example, tantalum oxide (Ta205), is sputtered using an argon (A) target total RF sputtering system.
r) Formed on a glazed alumina substrate by sputtering in scum or argon (Ar), oxygen (02) gas.

Alternatively, tantalum (Ta) is sputtered using a PC or RF sputtering device to form a tantalum film on a glazed alumina substrate, and then heat treated in the atmosphere at 600'C for 5 to 10 hours to form tantalum oxide (Ta205). Formed into. The film thickness of this certain plate protective film (3) is, for example, 400
-1000A. A tantalum-based resistor thin film (4) is formed on the substrate guarantee film (3). An example of the material for the tantalum-based resistor thin film is tantalum nitride.

Ta-81C++ Cermet+ TaSi'f
x There is somewhere. Next, on the resistor thin film (4), a conductor thin film (5) which will become the wiring conductor of the heating resistor is formed using a vacuum evaporation method or a sputtering method.

Then, the conductor thin film 114 (51) and the resistor thin film (4) are formed into a desired pattern using ordinary photolithographic etching technology.A perspective view of the thermal head after etching is shown in Fig. 2. Thereafter, a wear-resistant film (7) is placed above the heating resistor (4) to prevent wear caused by sliding with the thermal recording paper (not shown).This state is shown in the cross-sectional view of Fig. 3.Also, when an anti-oxidation film f61 for preventing oxidation of the heating resistor (4) is provided between the heating resistor (4) and the wear-resistant film (7). It can be used as a protective film such as an antioxidant film (6j, wear-resistant film (7)
B1Ox, 5iaNa, 81C, Ta2O3, etc. are used, and they can be processed by vacuum vaporization method, sputtering method,
Arike Plasma CV D (Chemical Va
-pour deposition) method.

The resistor thin film (4) is formed into an L-repattern using a photolithographic etching technique using a conventional photosensitive resin. The resistor thin film (41fK: had been removed).

Therefore, as shown in Figure 4, which is a cross-sectional view of the thermal head after etching when there is no substrate protection film (substrate protection film).
If 3) is not present, the glaze on the glazed alumina substrate will be corroded. Therefore, the characteristics of the thermal head deteriorate, and the protective films such as the anti-oxidation film (6) and the wear-resistant film tend to crack during use, resulting in a shortened lifespan of the thermal head.

) Note that when unnecessary portions of the resistor thin film (4) were removed using a hydrofluoric acid solution, the glaze layer (2) was corroded by about 5 to 20 μm in the absence of a substrate protective film.

As mentioned above, conventional thermal heads use a hydrofluoric acid solution for patterning tantalum resistor thin films.
To protect the substrate, a hydrofluoric acid-preventing substrate protective film was required between the glaze layer and the tantalum resistor thin film. For this reason, the number of steps in manufacturing the thermal head has increased. In addition, since a hydrofluoric acid solution is used, there are problems such as poor work safety and waste liquid treatment.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and includes a substrate fully coated with glass or quartz,
By having a tantalum-based resistor formed directly on this substrate and a wiring conductor connected to this resistor, there is no need for a protective film against hydrofluoric acid on the substrate, so a thermal head with a simple configuration can be realized. can get. Further, a tantalum-based resistor is formed on the substrate, a mask of a desired shape is formed on the resistor, and the tantalum-based resistor is selectively etched using gas plasma containing fluorine atoms, using the entire mask. In particular, even without a protective film, there is less erosion of the glass or quartz on the substrate, less side etching, and improved selective etching accuracy and reproducibility of the resistor.Furthermore, since no hydrofluoric acid solution is used, the work is easy. The purpose is to provide a complete manufacturing method that has good performance and no problems such as waste liquid treatment.

Hereinafter, a thermal head according to an embodiment of the present invention will be described with reference to FIG. 5, which is a perspective view of the vicinity of the tantalum heating resistor section. For example, a +11 H substrate, in this case an Id alumina substrate, (2) a glass or quartz covering layer (hereinafter referred to as a glaze layer) formed on a C substrate +1+, [+1 and (2) an insulating substrate] Made of glazed alumina substrate. (4) is a setantalum resistor, and (5) is a wiring conductor. The glaze layer (2) may be formed on the entire surface of the care alumina substrate [11] or only in the vicinity of the tantalum resistor (4).

The thickness of the glaze layer is important for the thermal responsiveness and thermal conductivity of the tantalum-based resistor (4), and is determined depending on the required characteristics of the thermal head, but is usually 20 to 1.
00/1m.

A tantalum resistor thin film (4) is formed on this glazed alumina substrate. Examples of the tantalum-based resistor thin film (4) include Ta-8i02 cermet, Ta-8i cermet, tantalum nitride, boride, and carbide.

There are silicides, oxides, etc.

A wiring conductor (5) is formed on the tantalum resistor thin film (4) by appropriately employing a vacuum evaporation method, a sputtering method, or the like. It is difficult to use as a wiring conductor (5), for example, Ti,
Cr, Pt, Au, A40u or 0r-A/
,, 0r-Au.

C! r-Ano Or, Or -Au-Cr, Cr-
These metal multilayer structures such as Cu and Cr-Cu-0r are used.

Next, a method for manufacturing a thermal head according to the present invention will be explained with reference to the drawings. Figure 6 shows the thermal head after conductor etching and stripe formation, and Figure 7 shows the thermal head after plasma etching. In FIG. 1, (8) is a half-odd resist.

As described above, after the tantalum resistor (4) and the wiring conductor thin film (61) have been completely formed on the substrate, a photoresist pattern is formed by the photolithographic etching method used on a normal photoresist, and the wiring conductor (5) is formed. Etching, wiring, wire conductor (6
) are formed as shown in Figure 6. Next, by plasma etching using a gas containing fluorine atoms, the tantalum resistor thin film (4) is etched as shown in FIG.

Gases containing fluorine atoms include, for example, OFt, C01
Fa.

CClF2. Alternatively, if a gas containing fluorine atoms mixed with an inert gas or oxygen gas is introduced into a reduced pressure plasma etching device to generate plasma,
The tantalum resistor thin film (4) reacts with the bagasse plasma to vaporize and evaporate, completing the etching. In the case of a tantalum-based resistor having a plasma etching time td of 5000 A, the etching was performed in, for example, 5 to 10 minutes, with almost no erosion of the underlying glaze layer, although it varied depending on the composition of the material 2 and the plasma generation conditions.

Examples of plasma etching apparatuses suitable for carrying out the present invention include parallel plate electrode type plasma etching apparatuses and cylindrical type plasma etching apparatuses.

Parallel plate electrode type plasma etching equipment includes, for example, DFiA-5032 manufactured by Nikkei Anelva Co., Ltd., and 011J-2120A manufactured by Japan Vacuum Technology Co., Ltd., and cylindrical type plasma etching equipment such as manufactured by Tokyo Ohka Kogyo Co., Ltd. There is OPM-600.

As shown in FIG. 7, after plasma etching the tantalum resistor thin film, the photoresist can be easily removed using oxygen gas plasma.

Next, using an ordinary photoresist, the wiring conductor in the portion to become the tantalum heat generating resistor is removed by photolithographic etching as shown in FIG.

A protective film such as an anti-oxidation film or an abrasion-resistant film such as 5in2.5isNt, Sin, Ta*05, etc. is formed on the tantalum-based heating resistor and in the area where it comes into contact with the thermal recording paper using a sputtering method. One heating element of the head is created.

A desired number of tantalum heating resistor elements are formed on the alumina substrate, and a driving circuit for the tantalum heating resistor elements may also be mounted.

8th National Disaster This is a configuration diagram showing a cylindrical plasma etching apparatus according to the present invention. In the figure, (9) is a plasma reaction vessel, tlol fl vacuum pump, (llllU high frequency power supply, (121 is a high frequency electrode, 1131 is a gas cylinder,
(141 is a gas flow meter.

A plasma reaction vessel (9) made of glass or quartz is charged with a K etching sample, and the vacuum pump (10) is fully operated so that the reaction vessel is maintained at a predetermined degree of vacuum.

When the high frequency power source (11) is activated to apply a bright frequency electric field to the high frequency electrodes f121vc arranged around the cylindrical reaction vessel, low temperature gas plasma is generated inside the reaction vessel (9) by glow discharge. Etching gas is supplied from a gas cylinder (13) and VC is adjusted by a gas flow meter (I4)K so that the pressure within the reaction chamber is at a desired level.

The surface of the sample to be processed is exposed to low-temperature gas plasma for a certain period of time, and after the desired portion of the resistor thin film on the surface of the sample to be processed has been etched, the high frequency power supply and vacuum evacuation are stopped.
Take out the processed sample from the reaction container. Photoresist is
Either positive type or negative type photosensitive resin may be used.

The pressure of the reaction vessel that generates low-temperature gas plasma is 10 m.
In the range from Torr to about 10 TOrr, around 0.5 TOrr is the worst. 13.56MHz applied at this time
Appropriate high frequency power u is about 1ooW to 5ooW.

Next, examples will be presented.

Example 1 T as a tantalum resistor on a glazed alumina substrate
4000A of a-8iOs+cermet was formed. Ta
-EliOQ cermet was formed using Ta and 8102 mosaic target iRF magnetron sputtering method. A target occupying an area ratio of 25 of the Ta-ke target was used.

Further, as a wiring conductor, Cr was formed at 200A, and then At was formed at 1 .mu.m on the Ta-8iO2 cermet using a DC magnetron sputtering method.

Next, photoresist manufactured by Tokyo Ohka Kogyo ○FPR-8
After forming a photoresist pattern using ordinary photolithography using A00, A
tf etching and further cerium ammonium nitrate.
Or was etched using a perchloric acid solution. After that, a cylindrical plasma etching apparatus O manufactured by Tokyo Ohka Kogyo Co., Ltd.
Gas plasma etching of Ta-8i02 cermet was performed using PM-1000. C as an etching gas
When F4 +02 (+, %)'c was used, the pressure inside the reaction vessel was set to 5 Torr, and RF power of 250 wk was applied, the Ta-8i02 cermet was etched in about 3 minutes. At this time, the thickness of the photoresist is 0.
The erosion of the glaze layer of the glazed alumina substrate was less than 500A. However, the side etching lj of the glaze layer under the heating resistor was 171 m or less, which was good. The photoresist was removed using the same cylindrical type 1 plasma etching apparatus by applying 02 gas I Torr K and RF power of 500 W for 10 minutes. Subsequently, the portion that would become the heating resistor was removed using the same photolithographic etching method as Or and Atf, to form the heating resistor of the thermal head and its lead electrode. The thermal head thus produced was of good quality.

Example 2 Ta-Eli cermet i 3000A was formed as a tantalum resistor on a glazed alumina substrate.

It was formed by RF sputtering using Ta-8i cermet IdTa and a mosaic target No. 81.

Thereafter, a thermal head was manufactured in the same manner as in Example 1, and a good one was obtained.

If gas plasma etching is also applied to the Cr and kl wiring conductors, the entire process can be performed using dry etching without using a solution, which not only enables highly accurate, uniform, and reproducible patterning, but also eliminates the problems associated with conventional waste liquid treatment. ,
Improves work efficiency.

Furthermore, when At is used as a wiring conductor for a tantalum-based resistor thin film, A/-! Since it is hardly corroded by l-jl- based gas plasma, it can also be used as a mask for tantalum based resistor thin films.

As explained above, the present invention is constructed to include a substrate covered with glass or quartz, a tantalum-based resistor formed directly on the substrate, and a wiring conductor connected to the resistor. Since there is no need for a hydrofluoric acid retaining film on the substrate, a thermal head with a simple structure can be obtained. or,
A tantalum-based resistor is formed on the above substrate, a mask of a desired shape is formed on this resistor, and the tantalum-based resistor is formed using the entire mask. Thermal head kff is fabricated by selective etching using gas plasma containing fluorine atoms.
Even without a protective film, there is less corrosion of the glass or quartz on the substrate, less side etching, better precision and reproducibility of selective etching of the resistor, and no need to use hydrofluoric acid solution sound, making the work easier. This has the effect of improving performance and eliminating problems such as waste liquid treatment.

[Brief explanation of drawings]

Figures 1 and 2 show a conventional thermal head in the order of steps; Figure 1 is a perspective view showing the state after wiring conductors are formed; Fig. 3 is a cross-sectional view showing the state with a protective film attached, Fig. 4 is a cross-sectional view showing the state after resistor etching by conventional method KL without a substrate protective film, and Fig. 5 is a thermal head of the present invention. FIG. 6 and FIG. 7 are perspective views showing an embodiment of the present invention, and FIGS.
FIG. 6 is a perspective view after forming conductor stripes, FIG. 7 is a perspective view after resistor etching, and FIG. 8 is a configuration diagram showing a cylindrical plasma etching apparatus according to the present invention. In the figure, [IN''j: substrate, in this case an alumina substrate, (2) a glass or quartz coating layer, (3) a substrate strip, a protective film, (4) a tantalum resistor, (5) is the wiring conductor,
(9) is a plasma reaction vessel, TIO+ fl vacuum pump, [+11] high frequency power supply, (12I frequency control electrode, (
+31fi gas cylinder, (14) is a gas flow meter. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Makoto Kuzuno - Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Procedural amendment (voluntary) 2. Name of the invention Thermal head and its manufacturing method 3. Amendment Relationship with the case of a person who does Column 6 of Detailed Description of the Invention, Details of Amendment (1) "Thermal head" in line 9 of page 2 of the specification is corrected to "thermal head." (2) Correct rpcJ on page 4, line 7 to "DC". (3) rccj? on page 9, line 10? F2J is called “CCl
Corrected to 2F2J. that's all

Claims (1)

[Scope of Claims] (1) A thermal head comprising a glass-clad quartz-covered substrate, a tantalum-based resistor formed directly on the substrate, and a wiring conductor connected to the resistor. (2) The thermal head according to claim 1, wherein the substrate is an alumina substrate. )3) The tantalum resistor is Ta-8iOa cermet. 2. The thermal head according to claim 1, which is one of Ta-8i cermet, tantalum carbide, tantalum nitride, tantalum boride, tantalum silicide, and tantalum carbide. (4) A tantalum-based resistor is entirely formed on a substrate covered with glass or quartz, a mask of a desired shape is formed on this resistor, and the mask is applied to make the tantalum-based resistor contain all fluorine atoms. A method for manufacturing a thermal head that performs selective etching using gas plasma. (5) The method for manufacturing a thermal head according to claim 4, wherein the substrate is an alumina substrate. (6) The tantalum resistor is Ta-F3102 cermet. Manufacture of a thermal head according to claim 4 or 5, which is any one of Ta-8i cermet, tantalum carbide, tantalum nitride, tantalum boride, tantalum silicide, and tantalum oxide. Method.