JPH06135035A - Fabrication of thermal head - Google Patents

Abstract

PURPOSE:To fabricate a thermal head in which adhesion is enhanced among an electrode film, an underlying film, and a protective film. CONSTITUTION:A resistive film and an electrode film are patterned at first and then the surface, on which a heating resistor 4 and electrodes 5, 6 are formed, is subjected to treatment with an acid containing water by 20vol.% or less or an acid containing any one of phosphate ion, silicate ion, or chromate ion and a protective film is formed thereon. A part of the resistive film is then subjected to dry etching using a halogen based gas and reaction products remaining on the surface of an underlying film 3 or thereabout are removed through wet treatment using an acid or hot water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thermal head.

[0002]

2. Description of the Related Art Thermal heads are used in various recording devices such as facsimiles and word processing printers because they have the advantages of low noise, easy maintenance, and low running cost.

In a thin film type thermal head, for example, alumina is used as a supporting substrate. Then, a glass glaze layer is formed on the surface of the alumina for the purpose of smoothing the surface of the alumina or for the purpose of heat retention.

When a glass glaze layer is formed on the surface of alumina, even if a heating resistor is formed in contact with the glass glaze layer, there is no practical problem when it is used in a normal facsimile or the like.

However, when it is used in a high-speed facsimile machine or a high-definition printing machine, the temperature of the heating resistor becomes high during operation. Therefore, when the glass glaze layer and the heating resistor are in contact with each other, the free components of the glass glaze layer diffuse into the heating resistor, and the resistance value of the heating resistor changes, thereby shortening the life. As a solution to this, a base film having high heat resistance and high insulation is formed in the lower layer of the heating resistor so that free components of the glass glaze layer do not diffuse into the heating resistor. The base film not only prevents free components of the glass glaze layer from diffusing into the heat-generating resistor, but also prevents heat generated by the heat-generating resistor from being directly applied to the heat-resistant resin layer or heat-resisting layer located below it. Performs functions such as supplementing the hardness of the resin layer.

[0006] By the way, a device using a thermal head, such as a facsimile or a word processor, is required to be small in size, low in power and low in price. Therefore, it is desirable that the thermal head be inexpensive and highly efficient.

In response to such a demand, a thermal head has been proposed in which the heat retaining layer is made of a heat resistant resin such as polyimide resin or epoxy resin instead of the glass glaze layer (see Japanese Patent Laid-Open No. 52-100245).

When the heat insulating layer is made of a heat resistant resin, the thermal efficiency is improved and the thermal response is improved as compared with the case where the glass glaze layer is used.

Now, a conventional method of manufacturing a thermal head will be described with reference to FIG. 2, taking a case where the heat insulating layer is made of a heat resistant resin as an example.

FIG. 2 is a partially exploded perspective view showing the main part of the thermal head.

The support substrate 21 is made of SUS, for example. The heat-resistant resin layer 22 is formed on the support substrate 21 with, for example, a polyimide resin.

A base film 23 is formed on the heat resistant resin layer 22 by a sputtering method.

The base film 23 is mainly composed of Si, N,
O, Zr, etc. The base film 23 containing Si, N, O, Zr or the like as a main component has excellent mechanical strength as compared with the Si—O—N type and is suitable for reinforcing the heat resistant resin layer 22.

Next, a resistance film containing Nb, Si, O, etc. as a main component, and an electrode film made of Al, etc. are sequentially formed on the base film 23.

The resistance film and the electrode film are processed by a photo-etching process, the resistance film is formed into a plurality of heating resistors 24, and the electrode film is an individual electrode 25 for individually supplying a current to each heating resistor 24. It is formed on the common electrode 26.

When etching the resistance film, plasma etching using a mixed gas of a fluorocarbon gas and an oxygen gas is also used.

After the heating resistor 24 and the electrodes 25 and 26 are formed, a protective film 27 is formed so as to cover the heating portion of the heating resistor 24 and its periphery. The protective film 27 is made of Si,
It is mainly composed of N, O and Zr.

After the various layers and films from the heat-resistant resin layer 22 to the protective film 27 are formed on the support substrate 21 by the above method, a thermal head is assembled through a mounting process.

By the way, as a photoetching process for processing the resistance film and the electrode film, a chemical dry etching (CDE) method is used for the resistance film and a wet etching is used for the electrode film.

A reactive gas such as CF ₄ or O ₂ is used in the CDE method.

Further, plasma ashing using a reactive gas such as CF ₄ or O ₂ is used to remove the photoresist used in the photoetching process.

[0022]

In the conventional method of manufacturing a thermal head, Nb contained in the resistance film and each fluoride of Zr contained in the base film react during the photoetching process, for example, the CDE method for the resistance film. Generated, and some of these substances adhere to the side surface of the electrode.

Further, when etching the electrode film, the substance generated by the reaction between the material of the electrode film and the etching gas may remain in an unstable form.

When the resist is removed by ashing, the ashing gas acts on the exposed surface of the electrode for a certain period of time.

As a result, the ashing gas reacts with the electrode, and a product of the reaction is formed on the electrode surface.

The substances produced in various steps as described above adhere to the electrodes. In addition, reaction products flying from other supporting substrates or chamber walls may adhere to the electrodes. When an unnecessary substance adheres to the electrode, the adhesion between the electrode and the protective film covering the upper part of the electrode becomes weak.

If the resist remains on the electrode, the surface of the electrode remains contaminated unless it is washed or handled properly thereafter.

If the protective film is formed in a state where the surface of the electrode is contaminated, the adhesive force between the electrode and the protective film is weak and a good quality thermal head cannot be obtained.

The adhesion of the reaction product to the electrode and the contamination of the electrode are not limited to those in which the heat insulating layer is formed of the heat resistant resin, but also in those in which the glass glaze layer is formed on the supporting substrate such as alumina. However, the above-mentioned problems are more remarkable in the thermal head in which the heat insulating layer is formed of the heat resistant resin.

It is considered that the cause is that the surface of the electrode film becomes uneven due to the influence of gas released from the heat-resistant resin when forming the electrode film and the unevenness of the surface of the base film. If the electrode film surface has irregularities, reaction products and contaminants are likely to remain correspondingly.

Further, during the photoetching process, for example, the CDE method for the resistance film, a part of the base film under the resistance film is exposed. When the base film is exposed, a substance generated by the reaction of the CDE method, for example, Nb fluoride contained in the resistance film remains on the surface of the base film or is redeposited.

In the layer close to the surface of the base film, a reaction product of the material forming the base film and the etching gas is formed. Of these reaction products, substances such as SiF ₄ having a sufficiently high vapor pressure are gasified and removed. But Z
R-fluoride and the like tend to remain in an unstable form.

If reaction products remain on the surface of the base film or a layer close to the surface, these reaction products affect and weaken the adhesion between the base film and the protective film.

Further, when etching the resistance film, the base film is exposed to plasma even when plasma etching using a mixed gas of a fluorocarbon gas and an oxygen gas is used. As a result, fluoride is generated in the base film, the adhesion between the base film and the protective film deteriorates, and the protective film floats or peels off.
It reduces the quality and yield of the thermal head.

It is an object of the present invention to provide a method of manufacturing a thermal head, in which the adhesion between the protective film and the electrode film or the base film is strengthened.

[0036]

The present invention comprises a step of forming a resistance film and an electrode film on a supporting substrate, a step of patterning the resistance film and the electrode film to form a heating resistor and an electrode, A method of manufacturing a thermal head, comprising a step of forming a protective film so as to cover at least a part of the heating resistor and the electrode, wherein the resistance film and the electrode film are patterned to form the heating resistor and the electrode. The protective film is formed by treating the surface with an acid having a water content of 20 vol% or less or an acid containing any of phosphate ion, silicate ion and chromate ion.

Further, according to the present invention, the step of forming an insulating base film on the support substrate, the step of forming a resistance film and an electrode film on the base film, and the resistance film formed on the base film. A step of dry-etching at least a part of the base film with a gas containing a halogen-based gas to expose the underlying film,
Removing the reaction product remaining on or near the surface of the underlying film after dry etching the resistance film by wet treatment with acid or warm water, and at least a part of the underlying film from which the reaction product has been removed And a step of forming a protective film so as to cover the.

Further, according to the present invention, a step of forming a heat-resistant resin layer on a support substrate, a step of forming a base film on the heat-resistant resin layer, a resistance film formed on the base film, and the resistance film In the method of manufacturing a thermal head, the method comprises the steps of etching a heat-generating resistor to form a protective film, and forming a protective film so as to cover at least the heat-generating resistor. It has a step of performing plasma etching with a mixed gas of gases and a step of performing ion bombardment.

[0039]

When the surface of the electrode was treated with various treatment liquids and the adhesion between the electrode and the protective film was examined, the following results were obtained.

(1) When the electrode (mainly composed of Al) is treated with hot water, the adhesive force between the electrode and the protective film decreases. Also,
When the water temperature is high, the adhesive strength is significantly reduced. It is considered that this is because a film of alumina hydrate is formed on the surface of the electrode by the reaction between the electrode and water, and this film weakens the adhesive force between the electrode and the protective film.

(2) When the electrode (mainly composed of Al) is treated with alkali, the adhesive force between the electrode and the protective film decreases.

Although the electrode surface is cleaned by the alkali treatment, a coating film of aluminum hydroxide or alumina hydrate is formed on the surface at this time, and this coating film weakens the adhesion with the protective film. It is thought to be because.

(3) When the electrode (mainly composed of Al) is treated with an acid, the adhesive force between the electrode and the protective film is improved or decreased depending on the treatment conditions.

When hydrochloric acid, nitric acid, sulfuric acid or the like is used, when the water content is less than 20%, the adhesive force tends to be improved when the water content is less than that, and when the water content is larger, the adhesive force tends to be decreased. Indicates.

If the degree of formation of alumina hydrate by the reaction between water in the treatment liquid and Al of the electrode material is greater than the degree of cleaning the electrode surface with acid, the adhesive force is lowered. Inferred. In this case, since the surface of the electrode is cleaned, it is considered that the reaction with water easily proceeds even at low temperature. On the other hand, in the case of an acid having a low water content and a high concentration, a stable oxide film is formed on the surface of the electrode, and as a result,
It is considered that the growth of the hydrate film is suppressed and the adhesion is improved.

(4) An acid containing any one of phosphate ion, silicate ion and chromate ion has a great effect of suppressing the formation of alumina hydrate, and when treated with an acid containing the above ion, the water content may be different. The adhesion between the electrode and the protective film is improved.

It should be noted that the growth of alumina hydrate is promoted at a pH of 7 or more, and does not grow at a pH of 5 or less. Further, many anions suppress the formation of the alumina hydrate coating, but phosphate ions, silicate ions, and chromate ions are said to have a particularly large suppressing effect.

(5) When treated with a mixed acid containing phosphoric acid, acetic acid and nitric acid as main components, the electrode containing Al as a main component is uniformly and stably etched. Therefore, it is suitable as a processing liquid. When treated with a mixed acid, it is considered that the formation of alumina hydrate is suppressed by phosphate ions, the viscosity is reduced by nitric acid, and the Baaer effect of etching by acetic acid functions effectively. Further, when the reaction product on the base film was removed by using several kinds of treatment liquids and the adhesive force between the base film and the protective film was examined, the following results were obtained.

In this case, the inventors of the present invention conducted Auger electron spectroscopy on the base film and the electrode for the sample which was not subjected to any treatment after the photoetching process for the resistance film and the samples which were subjected to several kinds of wet treatment. Law (hereinafter AE
Say S. ) Or X-ray photoelectron spectroscopy (hereinafter referred to as XPS) to analyze substances present on the surface.

After that, each sample was covered with a protective film, and the adhesive force between the base film and the protective film was evaluated.

(1) After the photo-etching process, a base film (a glass glaze layer having alumina as a supporting substrate and having a glass glaze layer formed on the surface thereof; the same applies to the following [Function]). There is a considerable amount of F on the surface. It is considered that F is the element contained in the resistance film, the base film, or the electrode film, which forms fluoride by the CDE method or the ashing step and remains as it is, or the element which has been once removed is attached again.

(2) When treated with acid or warm water, the F concentration on the surface of the base film is lowered. It is considered that this is because the fluoride is dissolved or decomposed and removed by the treatment with acid or warm water.

(3) The lower the F concentration on the surface of the base film and the electrode, the better the adhesion between the base film and the protective film.

Therefore, unstable reaction products such as fluorides can be removed or reduced from the surface of the base film by the above treatment, and the adhesion between the base film and the protective film is improved.

When the resistance film is plasma-etched with a mixed gas of a fluorocarbon-based gas and an oxygen gas, ion bombardment is performed thereafter. Therefore,
The fluorine compound generated in the base film during plasma etching can be removed or reduced, the adhesion between the base film and the protective film is enhanced, and the adhesive force with the protective film is improved.

Ion bombardment is known as a cleaning method immediately before forming various films. However, in the manufacturing process of the thermal head, if the ion bombardment is performed immediately before forming the protective film, it will cause deterioration of the heating resistor and deterioration of the resistance value distribution. For this reason, ion bombardment is performed after plasma etching of the resistance film and before the step of etching the electrode film exposing the heating resistor.

It is desirable that the ion bombardment is performed by exchanging only the etching gas immediately after the plasma etching of the resistance film.

As described above, according to the method of manufacturing the thermal head of the present invention, unstable reaction products and contaminants remaining on the electrodes and the base film can be removed, and the electrodes, the base film and the protective film can be removed. The factor that weakens the adhesive force of can be suppressed.

As a result, the protective film can be covered in a state where the electrode and the base film are clean, and good adhesion between the electrode and the base film and the protective film can be obtained.

[0060]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIG. 1, taking as an example the case where the electrode surface is treated with a mixed acid.

First, 1 is a supporting substrate made of a Fe--Cr alloy, and a heat-resistant resin layer 2 is formed on the supporting substrate 1 using an aromatic polyimide resin having a siloxane bond to a thickness of about 20 μm.

The support substrate 1 is not limited to the Fe-Cr alloy, and other metals or nonmetals can be used. The material of the heat resistant resin layer 2 is not limited to the aromatic polyimide resin. The heat resistant resin layer 2 is usually 10 μm to 40 μm
However, the thickness is not limited to this range.

The heat-resistant resin layer 2 is, for example, a polyamic acid varnish prepared by dissolving polyamic acid in an organic solvent.
It is formed by a method of coating on and baking.

There are various methods for applying the polyamic acid varnish, and for example, the spin coating method is used.

The firing of the polyamic acid varnish is performed at 90 ° C. for 60 minutes and 180 ° C. for 60 minutes in a dry nitrogen gas atmosphere.
Min., 450 ° C., 60 min.

Next, a base film 3 containing Si, O, N, and Zr as main components is formed on the heat-resistant resin layer 2 by using a sputtering method.

In this case, the target used is a powder of Si ₃ N ₄ and ZrO ₂ with a mol ratio of 9: 1, to which a small amount of a sintering additive is added, mixed, and hardened and sintered by hot pressing. To be done.

The support substrate 1 on which the heat-resistant resin layer 2 is formed is kept at 250 ° C. in the chamber and degassed for 1 hour, and then the base film 3 is formed. The degree of vacuum in the chamber at this time is 5 to 8 × 10 ⁻⁴ Pa.

The thickness of the base film 3 is about 3 μm, the lower layer 2 μm is in an Ar atmosphere, and the upper layer 1 μm is 10% O _2.
In an Ar atmosphere, sputtering is performed at a gas pressure of 2 × 10 ⁻¹ Pa.

The material of the base film 3 and its forming method are not limited to the above.

On the base film 3, Nb-SiO ₂
A system resistance film is formed by the sputtering method.

The material of the resistance film may be another material such as Ta-SiO ₂ system.

After forming the resistance film, annealing is performed in a vacuum heating furnace. Annealing is from room temperature to 450 ° C 1
The temperature was raised over a period of time, and the temperature was maintained at 450 ° C. for 30 minutes, followed by furnace cooling. During this time, the degree of vacuum in the heating furnace was on the order of 10 ⁻⁴ Pa.

Next, an Al electrode film serving as an individual electrode was sequentially formed by a sputtering method, and an Al electrode film serving as a common electrode was sequentially formed by a vacuum deposition method.

Other materials such as Al alloy can be used as the material of the electrode film.

After forming the resistance film and the Al electrode film, a photoetching process was performed to form the heating resistor 4, the individual electrode 5 and the common electrode 6. In this case, the photoetching process was performed in two stages.

First, the electrode film and the resistance film between the bits during printing are sequentially etched, and then the electrode film above the heat generating portion is removed to expose the heat generating portion of the heat generating resistor 4. . At this time, a mixed acid composed of phosphoric acid, acetic acid and nitric acid is used for etching the electrode film.

The CDE method was used for etching the resistance film. For example, CF ₄ and O ₂ are used as introduction gases,
The ratio is 7: 3.

After etching by the CDE method, the resist in the first stage was removed by ashing with a mixed gas of 5% CF ₄ —O ₂ and subsequent ashing with O ₂ . The ashing with the mixed gas is necessary to remove the resist-altered film by CDE.

The resist on the second stage was removed with a stripping solution.

After the above photo-etching process, carbon and fluorine, Nb of the resistance film material, etc. were detected from the surface of the electrode, and it was confirmed by AES or XPS surface analysis that the electrode surface was considerably contaminated. It was

After the photo-etching process, phosphoric acid,
A wet treatment with a mixed acid consisting of acetic acid and nitric acid was performed.
At this time, the treatment temperature was changed to 30 to 50 ° C. and the treatment time was changed to 20 to 200 seconds under different conditions.

Further, for the comparison of the characteristics, a sample not subjected to the wet treatment was also manufactured at the same time.

The wet-treated sample was immediately rinsed with a pure water shower and dried. AES and XPS
It was confirmed by the surface analysis by the method that the amount of fluoride on the electrode surface was decreased according to the conditions of the wet treatment.

After the wet treatment with mixed acid, the protective film 7 was formed so as to cover most of the electrodes 5 and 6 and the heating portion of the heating resistor 4.

The protective film 7 was formed by the same sputtering method as the base film 3. The target used was the same as that used for forming the base film 3.

The supporting substrate 1 on which the electrodes 5 and 6 and the heating resistor 4 are formed is kept at 250 ° C. in the chamber,
After degassing for 1 hour, the protective film 7 is formed.
The thickness is about 3 μm, and 2 μm of the lower layer is 10% O ₂ -A.
The sputtering was performed in an r atmosphere and 1 μm in the upper layer portion in an Ar atmosphere at a gas pressure of 2 × 10 ⁻¹ Pa.

After forming the protective film 7, each sample was subjected to boiling in boiling water, followed by tape peeling test and scratch test using a scratch tester.

As a result, it was confirmed that the adhesion between the electrode and the protective film was improved by the wet treatment with mixed acid.

Each thin film from the heat resistant resin layer to the protective film was formed on the supporting substrate by the above method, and the thermal head was completed through the subsequent mounting steps.

Next, the completed thermal head is heated to a temperature of 6
A bias voltage of 24 V was applied to the common electrode side under conditions of 0 ° C. and humidity of 90%, and a long-term environment resistance test was performed. As a result, in the case of the wet treatment with mixed acid, the protective film did not peel off and was stable for a long time. On the other hand, in the case where the wet treatment with mixed acid was not performed, the protective film on the electrode was partially peeled off, and the resistance value of the heating resistor constituting the print bit in the vicinity thereof was abnormal.

Example 2 A resistance film and an Al electrode film for an electrode are formed, and then a photoetching process is performed,
The process is the same as that of the first embodiment until the heating resistor 4, the individual electrode 5, and the common electrode 6 are formed. Heating resistor 4 and electrode 5,
The description up to the formation of 6 will be omitted because it is the same as that of the first embodiment.

In the second embodiment, with respect to the sample in which the heating resistor 4, the individual electrode 5, and the common electrode 6 are formed, fuming nitric acid, hydrochloric acid, nitric acid, sulfuric acid, acetic acid, nitric acid + acetic acid, sulfuric acid + acetic acid, or another acid is used. Wet treatment was performed at several concentrations.
The processing temperature is 25 to 50 ° C., and the processing time is 20 to 20.
It is in the range of 0 seconds. After that, a protective film was formed in the same manner as in Example 1.

As a result, it was confirmed that the adhesive strength was improved when treated with an acid having a water content of about 20% or less. A thermal head that was stable even after long-term operation was obtained.

(Embodiment 3) A resistance film and an Al film for electrodes are formed, and then a photo-etching process is carried out to form the heating resistor 4, the individual electrodes 5, and the common electrode 6 in the same manner as in Embodiment 1. Is. Therefore, the description up to this point is the same as that of the first embodiment and will not be repeated.

In Example 3, the sample on which the heating resistor 4, the individual electrode 5 and the common electrode 6 were formed was wet-treated with an acid having various water contents including any one of phosphoric acid, silicic acid and chromic acid. The processing temperature was 25 to 50 ° C., and the processing time was 20 to 200 seconds. Then, a protective film was formed in the same manner as in Example 1.

As a result, it was confirmed that the adhesive strength was improved. A thermal head that was stable even after long-term operation was obtained.

(Embodiment 4) The heat retaining layer 4 is formed by replacing the heat-resistant resin layer with a glass glaze layer and except for the structure in which the resistance film is directly formed on the glass glaze layer.
The process up to the formation of the individual electrode 5 and the common electrode 6 is the same as in the first embodiment. Further, a protective film was formed in the same manner as in Example 1, and these prototypes were evaluated in the same manner as in Examples 1 to 3. As a result, an increase in adhesion was confirmed. A thermal head that was stable even after long-term operation was obtained.

(Embodiment 5) A resistance film and an Al electrode film for an electrode are formed, and then a photoetching process is performed,
The process is the same as that of the first embodiment until the heating resistor 4, the individual electrode 5, and the common electrode 6 are formed. Therefore, the description up to this point is the same as that of the first embodiment and will not be repeated. However, the CDE method for etching the resistive film is not limited to the usual 70 seconds, but 1
It was performed under three conditions of 00 seconds and 130 seconds.

After the CDE method, the resist in the first step is 5%
It was removed by ashing with a mixed gas of CF ₄ —O ₂ and subsequent ashing with O ₂ . Note that the ashing with the mixed gas is necessary to remove the resist-altered film by the CDE method.

The resist on the second stage was removed with a stripping solution.

After the photoetching process described above, it is found that a considerable amount of fluoride is formed on the surface of the base film.
It was confirmed by ES and XPS surface analysis.

Further, as the time of the CDE method increased, the amount of fluoride also increased.

After the photo-etching process, phosphoric acid,
Wet treatment was performed with a mixed acid consisting of acetic acid and nitric acid. At this time, the temperature of the treatment liquid was changed in the range of 30 to 50 ° C., and the treatment time was changed in the range of 20 to 200 seconds. A sample without wet treatment was also manufactured as a trial for the comparison of characteristics.

The wet-treated sample was immediately rinsed with a pure water shower and dried. Here, Table 1 shows the relationship between the trial production conditions of the sample (CDE time, treatment liquid temperature ... liquid temperature, treatment time) and the adhesive force between the base film / protective film.

[0106]

[Table 1] The wet treatment is effective if it is performed at some stage after the CDE method and before the formation of the protective film. It was confirmed by surface analysis of AES and XPS that the amount of fluoride on the surface of the base film and the surface of the electrode was reduced according to the treatment conditions by the wet treatment.

After the wet treatment with the above mixed acid, a protective film was formed.

The protective film was formed by the same sputtering method as that for the base film. The target used was the same as that for forming the base film.

The supporting substrate on which the electrodes and the like were formed was kept at 250 ° C. in the chamber and degassed for 1 hour, and then a protective film was formed to a thickness of about 3 μm. 2μ in the lower layer
m is 10% O ₂ -Ar atmosphere, and 1 in the upper layer
μm was formed by sputtering in an Ar atmosphere at a gas pressure of 2 × 10 ⁻¹ Pa.

After forming the protective film, each sample was subjected to boiling in boiling water, and then a tape peeling test and a scratch test using a scratch tester were conducted to evaluate the adhesive force between the base film and the protective film. The results are shown in Table 1.

After forming the protective film, the mounting process is followed by
Completed Maruhead.

Next, the completed thermal head is heated to a temperature of 6
It was subjected to a long-term environment resistance test under the conditions of 0 ° C. and humidity of 90%. As a result, in the prototypes having the cross mark in Table 1, the protective film on the base film floated or peeled off, and the resistance value of the heating resistor bit in the vicinity of the peeled off was abnormal. There were no problems with other prototypes.

Example 6 A resistance film and an Al electrode film for an electrode are formed, and then a photoetching process is performed,
The process is the same as that of the first embodiment until the heating resistor 4, the individual electrode 5, and the common electrode 6 are formed. Therefore, the description up to this point is the same as that of the first embodiment and will not be repeated. 25 to 50 per sample after photoetching process
Wet treatment was carried out by using treatment liquids such as nitric acid, sulfuric acid, phosphoric acid, acetic acid, nitric acid + acetic acid, sulfuric acid + acetic acid, phosphoric acid + acetic acid, etc. at different temperatures. After that, a sample was experimentally manufactured by the same method as that of the above-mentioned embodiment.

As a result, the adhesive force between the electrode and the protective film deteriorated under some conditions, but the adhesive force between the base film and the protective film improved under any condition.

(Embodiment 7) A resistance film and an Al electrode film for an electrode are formed, and then a photoetching process is performed,
The process is the same as that of the first embodiment until the heating resistor 4, the individual electrode 5, and the common electrode 6 are formed. Therefore, the description up to this point is the same as that of the first embodiment and will not be repeated. 40 to 10 per sample after photoetching process
Wet treatment was performed by using warm water of 0 ° C. and changing treatment time. After that, a sample was experimentally manufactured by the same method as that of the above-mentioned embodiment. As a result, the adhesive strength of the protective film on the electrode deteriorated under some conditions, but the adhesive strength between the base film and the protective film improved under all conditions.

(Embodiment 8) A case where a base film having Si, N, O and Zr as a main component is formed on a supporting substrate having a heat insulating layer formed of a glass glaze layer and a resistance film is formed thereon. A sample was manufactured in the same manner as in the above example.

Further, a resistance film was directly formed on the glass glaze layer, and thereafter, a sample was manufactured by a method similar to that of the above embodiment. As a result of evaluating these prototypes in the same manner as in the above examples, it was confirmed that the adhesion between the glass glaze layer and the protective film was increased by the wet treatment.

Example 9 A heat resistant resin layer 2 is formed on a supporting substrate, and S is sputtered on the heat resistant resin layer 2.
Since the structure for forming the base film 3 containing i, O, N, and Zr as the main components is the same as that of the first embodiment, the description thereof will be omitted.

In the present embodiment, as a target for forming the undercoat film 3, a target was used in which powders of Si ₃ N ₄ and ZrO ₂ having a mol ratio of 4: 1 were mixed and hardened and sintered by hot pressing. An Nb—SiO ₂ -based heating resistor 4, an individual electrode 5 made of Al, and a common electrode 6 were formed on the base film 3. Materials other than those mentioned above can be used for the heating resistor 4 and the electrodes 5 and 6, and various forming methods thereof can be used.

Next, a protective film 7 was formed so as to cover most of the electrodes 5 and 6 and the heating resistor 4. The protective film 7 is coated by the same sputtering method as the base film 3,
The target used was the same as the base film 3.

Further, the etching of the resistance film forming the heating resistor 4 is carried out by reactive ion etching (RI) using a mixed gas of CF ₄ gas 70% and O ₂ gas 30%.
Then, the resist was peeled off by ashing by switching to a gas of O ₂ 100%. Furthermore, Ar100
% Gas was used and ion bombardment was performed. Ion bombardment was carried out for 5 minutes under the conditions of 4.0 × 10 ^-1 Pa and 0.35 W / cm ² . After that, a sample was experimentally manufactured by the same method as that of the above-mentioned embodiment.

The sample obtained in this example and the sample obtained in the prior art were cut by a cutter knife to about 1 mm.
After scratching to a size of 1, the adhesive strength of the protective layer was evaluated by a method of peeling with an adhesive tape. As a result, no peeling was observed in the sample of this example. Samples obtained by the prior art showed 1-5% delamination. The etching amount of the base film by the ion bombardment was measured and found to be 100 to 150 angstroms.

The same heat insulating layer having a glass glaze layer was manufactured by the same method and evaluated, and the same good result was obtained.

Although CF ₄ gas is used for etching the resistance film and Ar gas is used for the ion bombardment in this embodiment, C _n gas such as C ₂ H ₆ and C ₃ H ₈ is used for etching the resistance film.
The H _m based gas, also ionic Bomba - the He in de, Ne, K
It is also possible to use r, Xe or Rn gas.

[0125]

According to the method of manufacturing a thermal head of the present invention, it is possible to provide a highly reliable thermal head with improved adhesion between the protective film and the electrodes or the base film.

Further, the present invention is particularly effective for a thermal head using a heat-resistant resin in which the adhesive force of the protective film is likely to be unstable.

[Brief description of drawings]

FIG. 1 is a view for explaining an embodiment of the present invention and is a partially exploded perspective view showing a main part of a thermal head.

FIG. 2 is a view for explaining a conventional example, and is a partially exploded perspective view showing a main part of a thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Support substrate 2 ... Heat-resistant resin layer 3 ... Underlayer film 4 ... Heating resistor 5 ... Individual electrode 6 ... Common electrode 7 ... Protective film

Continuation of the front page (72) Inventor Teruaki Teruki, 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Stock Company Toshiba Horikawa-cho Factory

Claims (3)

[Claims] 1. A step of forming a resistance film and an electrode film on a supporting substrate, a step of patterning the resistance film and the electrode film to form a heating resistor and an electrode, and a step of forming the heating resistor and the electrode. In the method of manufacturing a thermal head, which comprises a step of acid-treating the surface, and a step of forming a protective film so as to cover at least a part of the heating resistor and the electrode, the acid used for the acid treatment is
A method of manufacturing a thermal head, which is an acid having a water content of 20 vol% or less, or an acid containing any of phosphate ions, silicate ions, and chromate ions. 2. A step of forming an insulating base film on a supporting substrate, a step of sequentially forming a resistance film and an electrode film on the base film, and at least the resistance film formed on the base film. A step of dry-etching a part of the base film by dry etching with a gas containing a halogen-based gas; and a step of forming a protective film so as to cover at least a part of the base film exposed by the dry etching. In the method of manufacturing a thermal head, the base film is made of a material containing Zr, and after the step of exposing the base film by the dry etching and before the protective film forming step, the surface of the base film or Z remaining near the surface
A method of manufacturing a thermal head, comprising a step of removing a reaction product containing r by a wet treatment with an acid or warm water. 3. A step of forming a heat-resistant resin layer on a supporting substrate, a step of forming a base film on the heat-resistant resin layer, a resistance film formed on the base film, and etching the resistance film to generate heat. In a method of manufacturing a thermal head, which comprises a step of forming a resistor and a step of forming a protective film so as to cover at least the heating resistor, the resistive film is a mixed gas of a fluorocarbon-based gas and an oxygen gas. And a step of performing ion bombardment, and a method of manufacturing a thermal head.