JPH07180044A - Sputtering target, substrate film for heating resistor and wear-resistant coating film formed by using the target and thermal printer head using those films - Google Patents

Abstract

PURPOSE:To provide a sputtering target with the generation of particles suppressed at the time of forming a film and a sputtering target capable of relieving the film stress. CONSTITUTION:A first sputtering target is a sintered target obtained by sintering a mixture contg. 1-45 molar % of the oxide of at least one kind of metallic element (Ml element) selected from Al, Cr, Ti, Zr, Hf, Mg and Y and substantially the balance silicon nitride. A second sputtering target is a sintered target formed by sintering a mixture contg. 1-40 molar % of chromium oxide, 0-30 molar % of the oxide of at least one kind of metallic element (M1 element) selected from Al, Ti, Zr, Hf, Mg and Y, where the total amt. is controlled to 1-45 molar %, and substantially the balance silicon nitride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target suitable for forming a base film or a protective film for a heating resistor for a thermal print head, a base film for a heating resistor and an abrasion resistant film formed by using the sputtering target. , And a thermal print head using them.

[0002]

2. Description of the Related Art Thermal heads are widely used in various recording devices such as facsimiles and word processor printers, taking advantage of low noise, low maintenance, low running cost and the like. As such a thermal print head,
A heating resistor layer and a conductor layer to be an individual electrode and a common electrode are sequentially formed on an alumina substrate having a glaze glass layer, and the outermost layer is a protective film for protecting the heating resistor layer and the conductor layer. Was generally formed by forming a coating.

However, in the thermal print head in which the heating resistor layer is directly formed on the glaze glass layer as described above, it is caused by diffusion of impurities and constituent substances at the interface between the glaze glass layer and the heating resistor layer. As a result, there has been a problem in that a remarkable change in resistance value of the heating resistor over time, such as a change over time or a breakage is likely to occur.

Therefore, in order to prolong the service life and reliability of the thermal print head, it has been attempted to form various insulating films on the glaze glass layer as an underlayer of the heating resistor. For example, Japanese Patent Application Laid-Open No. 61-297159 describes that a Si-ON film is used as the underlayer for the heating resistor. By using such a Si-ON based underlayer film, it is possible to prevent the diffusion of impurities and constituent substances between the glaze glass layer and the heating resistor layer, and thus suppress the resistance change rate of the heating resistor. Although possible, when depositing a Si-ON based underlayer by sputtering, particles that become foreign matter such as target crystal grains adhere to the substrate during deposition due to the low target density, and However, there is a drawback that it is difficult to obtain a base film having excellent surface properties and film thickness uniformity.

As described above, if the surface properties and the film thickness uniformity of the heating resistor base film are poor, the thickness of the heating resistor layer formed thereon is extremely small, ie, several hundreds nm or less. As a result, the film thickness of the heating resistor layer becomes non-uniform, and the resistance values of the individual heating resistors tend to vary. This causes a problem that the production yield is lowered and the heating resistor is changed with time. This is due to the material that makes up the target, as described above.
This is because the target used for forming the Si-ON-based underlayer film for the heating resistor is composed of silicon nitride and silicon dioxide, and in some cases, silicon nitride, silicon dioxide, and silicon. With such a material, the sintered target cannot be densified, and particles such as crystal grains of the target that become foreign matter adhere to the substrate during film formation.

In addition to Si-ON materials, silicon nitride or sialon (Si-Al-ON) can be used as a base film for heating resistors.
Have been proposed (see Japanese Patent Laid-Open No. 63-144058).
For example, although a target using sialon can be densified and generation of particles during sputtering can be reduced, compatibility with a heating resistor is poor,
In addition to being inferior to the original function of the underlayer film for heating resistors to prevent the diffusion of impurities and constituent substances, there is a problem that the thermal stress of the film is large and the reliability of the thermal print head is reduced. Was there.

On the other hand, also as a protective film for the above-mentioned thermal print head, the above-mentioned Si-ON-based film, silicon nitride film,
Although it has been attempted to use a sialon film or the like, for example, a Si-ON-based film has insufficient hardness as a protective film, and a silicon nitride film or a sialon film has a large film stress as described above. However, there was a problem that the durability was insufficient. It is particularly desired that the protective film of the thermal print head has excellent durability, but if the stress in the film is large, peeling or the like easily occurs, and sufficient durability cannot be obtained. Also, regarding the protective film of the thermal print head, if particles adhere to the substrate during film formation and the surface properties of the film and the uniformity of the film thickness are deteriorated, durability and reliability are deteriorated.

[0008]

As described above, in the conventional thermal print head, due to the fact that particles are likely to be generated during the sputtering film formation, the surface property and the film thickness are not uniform. Since it is difficult to obtain a ground film, there is a problem that the film thickness of the heating resistor layer becomes non-uniform, and individual resistance values of the heating resistors tend to vary. Further, the protective film has a problem that sufficient durability cannot be obtained due to the large stress of the film.

The present invention has been made in order to solve such a problem, and is a sputtering target suitable for producing an underlayer film for a heating resistor and an abrasion resistant film in which generation of particles during film formation is suppressed. Another object of the present invention is to improve the durability of the heating resistor underlayer film having excellent surface properties and film thickness uniformity by reducing the film stress. Another object of the present invention is to provide a wear-resistant coating and a thermal print head using the coating, which has excellent printing characteristics and reliability.

[0010]

[Means and Action for Solving the Problems] The first sputtering target in the present invention is Si-M1-ON (M1 is A
More specifically, it contains at least one metal element selected from l, Cr, Ti, Zr, Hf, Mg and Y (excluding the combination of Si-Al-ON) as a main constituent element. 1 to 45mo of an oxide of at least one metal element (M1 element) selected from Al, Cr, Ti, Zr, Hf, Mg and Y.
It is characterized in that it is obtained by sintering a mixture containing in the range of 1% and the balance substantially consisting of silicon nitride. Further, the heating resistor underlayer film of the present invention is a heating resistor underlayer film formed by sputtering using the above sputtering target, wherein Si-M1-ON (however, a combination of Si-Al-ON Is included as a main constituent element.

The second sputtering target in the present invention is Si-Cr-ON or Si-Cr-M2-ON (M2 is
At least 1 selected from Al, Ti, Zr, Hf, Mg and Y
A metal element of a seed) is contained as a main constituent element, more specifically, chromium oxide in a range of 1 to 40 mol%,
An oxide of at least one metal element (M2 element) selected from Al, Ti, Zr, Hf, Mg and Y in the range of 0 to 30 mol% is added to the total of the chromium oxide and the oxide of the M2 element. It is characterized in that a mixture is contained in an amount of 1 to 45 mol% and the balance is substantially composed of silicon nitride, which is obtained by sintering. The wear-resistant coating of the present invention is a wear-resistant coating formed by sputtering using the sputtering target, containing Si-Cr-ON or Si-Cr-M2-ON as a main constituent element. It is characterized by doing.

The thermal print head according to the present invention has the following features. That is, an insulating support base, a heating resistor base layer provided on the insulating support base, a heating resistor layer provided on the heating resistor base layer, and on the heating resistor layer. And a conductor layer for supplying power to the heating resistor provided in the first thermal print head.
The heat-generating resistor underlayer is formed of the heat-generating resistor underlayer film of the present invention, and a second thermal print head is characterized in that the protective film is formed of the abrasion-resistant film of the present invention. In the third thermal print head, the underlayer for the heating resistor is formed by the underlayer film for the heating resistor according to the present invention, and the protective film is provided with the abrasion resistance according to the present invention. It is characterized by being composed of a coating.

First, the underlayer film for a heating resistor of the present invention will be described. The underlayer film for heat-generating resistors of the present invention comprises at least one metal element (M1 element) selected from Al, Cr, Ti, Zr, Hf, Mg and Y in a silicon nitride-based sintering target.
By including the oxide of 3 to 45 mol% as the amount in the raw material mixture, the density of the sintering target can be easily improved, and the film containing the oxide of the M1 element (however, Si- (Except Al-ON combination) is based on the finding that it is possible to effectively prevent the diffusion of impurities and constituent substances between the heating resistor layer and the glaze glass layer. .

The first sputtering target in the present invention is suitable for forming the underlayer film for the heating resistor as described above. Here, if the amount of the M1 element oxide in the raw material mixture is less than 1 mol%, it is not possible to sufficiently improve the density of the sintering target, and at the same time, the effect of preventing diffusion of impurities and constituent substances of the obtained film is obtained. Is reduced. In addition, the amount of the M1 element oxide in the raw material mixture is
When it exceeds 45 mol%, the original properties of the obtained silicon nitride-based film are deteriorated, and the compressive stress of the film is increased to easily cause peeling or the like. The specific sintering density of the first sputtering target is preferably 75% or more. In the sputtering target of the present invention, such a sintering density can be obtained by a normal atmospheric pressure sintering method, an atmospheric pressure sintering method. Method, hot press method, etc. In addition, the raw material mixture used for producing the sputtering target may satisfy the above range as a ceramic composition,
An organic binder or the like can be used as in the case of manufacturing a normal sintered body.

Among the oxides of the M1 element described above, particularly Ti and Z
Oxides of r, Hf, Mg and Cr (M1 'element) are excellent in preventing diffusion of impurities and constituents, and Al and Y (M1 ″)
The oxide of the (element) greatly contributes to the improvement of the density of the sintered target. Although the density of the sintered target can be improved by using the M1 ′ element oxide alone, it is more preferable to use a mixture of the M1 ′ element oxide and the M1 ″ element oxide. Is M in the range of 1 to 20 mol%
It is preferable to use an oxide of 1 ′ element and an oxide of M1 ″ element in the range of 1 to 30 mol% mixed with silicon nitride so that the total amount is in the above range. Of these, Cr, Ti, Zr, and Hf exert a great effect on the stress reduction of the film, so by using these oxides alone or in combination with other oxides, It is possible to improve the adhesion to the resistor layer and the glaze glass layer.

By using the high-density sintered target as described above, it is possible to suppress the generation of particles during film formation, and thus the heating resistance of the present invention which is excellent in surface properties and film thickness uniformity. A base film for body is obtained. The heating resistor base film of the present invention has excellent surface properties and film thickness uniformity, is chemically and thermally stable, and further contains an oxide of the M1 element to provide good impurities and constituent substances. It has a diffusion preventing effect.
However, the use of Al oxide alone does not provide sufficient effect of preventing diffusion of impurities and constituents, and is therefore excluded from the scope of the present invention.

Next, the abrasion resistant coating of the present invention will be described. The wear resistant coating of the present invention is formed in a silicon nitride based coating.
By containing Cr, it is possible to significantly reduce the stress of the film and improve the sliding characteristics, and it is based on the finding that durability can be significantly improved by these. It is a thing.

The second sputtering target in the present invention is for obtaining such an abrasion resistant coating, and has a ceramic composition in the raw material mixture of 1 to 40.
Chromium oxide in the range of mol% and Al, T in the range of 0 to 30 mol%
It contains an oxide of at least one metal element (M2 element) selected from i, Zr, Hf, Mg and Y in the range of 1 to 45 mol% as the total amount of chromium oxide and the oxide of M2 element. .

If the amount of the above chromium oxide in the raw material mixture is less than 1 mol%, the effect of reducing the film stress and the sliding characteristics cannot be sufficiently obtained, and if it exceeds 40 mol%,
The original characteristics of the silicon nitride-based film, such as mechanical strength, are reduced. Further, even when chromium oxide is used alone, the density of the sintered target can be improved, but in order to improve the density more easily, M2
It is preferable to mix and use elemental oxides in a range of 30 mol% or less. However, if the amount of the oxide of the M2 element in the raw material mixture is too large, the stress of the film increases, so the content is set to 30 mol% or less.

Further, among the oxides of the M2 element, the oxides of Al and Y (M2 'element) particularly contribute to the improvement of the density of the sintered target, and hence their use is desirable. In this case, the raw material composition is as follows: chromium oxide in the range of 3-40 mol%, oxide of M2 'element in the range of 1-20 mol%, 0-30 mol%
Oxides of M2 elements other than M2 'of 1% or less as the total amount
It is preferable that the mixture is contained in the range of 3 to 45 mol% and the balance is substantially composed of silicon nitride. Further, the total amount of chromium oxide and the oxide of the M2 element is set in the range of 1 to 45 mol% for the same reason as the above-mentioned first sputtering target.

By using the above-mentioned sintered target containing chromium oxide as an essential component, the film stress is reduced and the abrasion resistant coating of the present invention, which has improved sliding characteristics, that is, Si-Cr-ON. Alternatively, a wear resistant coating containing Si-Cr-M2-ON as a main constituent element can be obtained. Such a wear-resistant coating film having a low film stress has excellent adhesion to the film-forming substrate, and thus the durability can be significantly improved. Further, since chromium oxide also contributes to the improvement of the sliding property of the film, it is possible to improve the durability of the wear resistant film also from these points. Further, since the second sputtering target can be easily densified with chromium oxide or an oxide of the M2 element, the surface properties and the film thickness are uniform as in the above-mentioned underlayer film for heating resistors. It is possible to improve the sex. Therefore, also from these points, the durability of the abrasion resistant coating is improved. The above Si-Cr
The film containing -ON or Si-Cr-M2-ON as a main constituent element is also useful as a base film for a heating resistor as described above.

Next, the thermal print head of the present invention will be described.

The first thermal print head according to the present invention uses the above-described base film of the present invention as a base layer for a heating resistor. This underlayer film for heating resistors is
As described above, since the surface properties and the uniformity of the film thickness are excellent, it is possible to make the film thickness of the heating resistor layer formed thereon uniform. As a result, it is possible to suppress variations in the resistance value of each heating resistor, and since the underlayer film has excellent chemical and thermal stability, it is possible to prevent the heating resistor from changing over time. The manufacturing yield is also improved. Further, it is possible to effectively prevent the diffusion of impurities, constituent substances, and the like between the heating resistor layer and the glaze glass layer, so that it is possible to suppress the resistance change rate of the heating resistor.

Further, the second thermal print head is
The wear-resistant coating of the present invention described above is used as the protective film. As described above, this protective film has low film stress, excellent hardness and abrasion resistance, and excellent surface properties and film thickness uniformity, which significantly improves the durability and reliability of the thermal printhead. Can be improved. Furthermore, since the above-mentioned protective film has a low coefficient of friction during sliding, damage to the recording paper can be reduced. The third thermal print head is a combination of the first thermal print head and the second thermal print head.

[0025]

EXAMPLES Examples of the present invention will be described below.

Example 1 First, an example of the first sputtering target and the heating resistor base film of the present invention will be described.

Si ₃ N ₄ powder having an average particle size of 1 μm or less,
Various metal oxide powders were added at the composition ratios shown in Table 1, and these were mixed for 72 hours with a ball mill using ethanol as a dispersion medium, and then dried and granulated. Next, these granulated powders were respectively sintered at a maximum temperature of 1750 ° C. while applying a maximum pressure of 25 MPa. After that, each of the obtained sintered bodies was ground into a shape having a diameter of 5 inches and a thickness of 5 mm, and these were joined to a cooling plate made of copper to obtain a sputtering target.

Each of the sputtering targets thus obtained was sputter-deposited on a glass substrate with an RF output of 2 kW in Ar gas. The characteristics of these sputtered films and sputtering targets were evaluated as follows. First, the porosity of each sintering target was determined by electron microscope observation after sputtering. Further, in order to evaluate the flatness of the film, a base film was formed to a thickness of 500 nm on a 50 mm square glass substrate, and the number of particles of 500 nm or more in the film was measured by a particle counter.

The comparative examples in Table 1 are films formed by sputtering using a conventional sputtering target under the same conditions, and the same evaluations as those of the above-mentioned examples were performed.

[0030]

[Table 1] As is clear from Table 1, the sputtering target of the present invention maintains a high density even after sputtering, and any film formed using such a target has excellent surface flatness. It was

Example 2 Next, an example of the second sputtering target and wear resistant coating of the present invention will be described.

Si ₃ N ₄ powder having an average particle size of 1 μm or less,
Various metal oxide powders were added at the composition ratios shown in Table 2, and these were mixed, dried and granulated under the same conditions as in Example 1. Next, these granulated powders were sintered under the same conditions as in Example 1, and a sputtering target was produced in the same manner.

Using each of the sputtering targets thus obtained, a film having a film thickness of 3 μm was sputter-deposited on a glass substrate by RF output in Ar gas. The characteristics of these sputtered films were evaluated as follows. First, the hardness of the film was measured using a Knoop hardness meter. In addition, using a Si substrate, the film stress was calculated from the amount of warpage and the film thickness before and after film formation. In addition, the film formed on the glass substrate has a thickness of 1 mm
Lattice-like cells were provided at intervals with a cutter, and a peeling test was performed using an adhesive tape, and the adhesion of the film was evaluated from the number of peelings. The results are shown together in Table 2.

[0034]

[Table 2] As is clear from Table 2, the film formed by using the sputtering target of the present invention has high hardness suitable for an abrasion resistant film and has low film stress, and therefore has excellent adhesion. It turns out that

Example 3 Next, an example of the first thermal print head of the present invention will be described.

First, as shown in FIG. 1, an alumina substrate 1 having a glass glaze layer 1a on its surface was used as an insulating support substrate, and each sputtering target obtained in Example 1 was used on the glass glaze layer 1a. In the Ar + O ₂ mixed atmosphere, the underlayer film 2 for heating resistors having a film thickness of about 100 nm was formed by the high frequency magnetron sputtering method. A Ta-SiO ₂ heating resistor layer 3 having a film thickness of about 50 nm was formed on the base film 2, and an electrode conductor layer 4 made of Al and having a thickness of 1.5 μm was formed. Next, the heating resistor layer 3 and the electrode conductor layer 4 were patterned by etching to form a common electrode, individual electrodes and a heating portion 5. After this,
A protective film 6 made of Ta ₂ O ₅ having a thickness of 3 μm is formed on the uppermost portion, and the desired thermal print head 7 is formed.
Got

Further, as a comparative example of the present invention, a thermal print head having the same structure as that of the above-mentioned example except that a base film is formed under the same conditions using a SiAlON-based sintered target and a SiON-based sintered target, A thermal print head having the same structure as that of the above-described example except that the base film 2 was not used was produced.

To each of the thermal print heads according to these examples and comparative examples, a pulse of energy of 0.15 J / dot was continuously applied to the heating resistor under the conditions of a pulse width of 0.8 ms and a repetition period of 2 ms. The resistance change rate of the heating resistor was measured. Table 3 shows the rate of resistance change when the number of pulses applied is 10 ⁸ .

[0039]

[Table 3] As is clear from Table 3, all of the thermal print heads using the underlayer film for heating resistors of the present invention have a small rate of resistance change. Therefore, it is possible to obtain stable printing characteristics for a long period of time.

Embodiment 4 Next, an embodiment of the second thermal print head of the present invention will be described.

As in Example 3, an alumina substrate having a glass glaze layer on its surface was used, and a Ta-SiO ₂ heating resistor layer having a film thickness of about 50 nm was formed on the glass glaze layer by a high frequency magnetron sputtering method. Further, an electrode conductor layer made of Al and having a thickness of 1.5 μm was formed. Then, the heating resistor layer and the electrode conductor layer were patterned by etching to form a common electrode, individual electrodes and a heating portion.
After that, each of the sputtering targets obtained in Example 2 was used to form a protective film having a thickness of 3 μm on the uppermost part by a high frequency magnetron sputtering method in an Ar atmosphere. Obtained.

As a comparative example of the present invention, the protective film is formed under the same conditions by using a SiAlON-based sintered target, a SiON-based sintered target and a Ta ₂ O ₅ -based sintered target, respectively. A thermal print head having the same structure as that of the example was manufactured. The friction coefficient of the protective film of each thermal print head according to these examples and comparative examples was measured. The friction coefficient was measured by using a scratch tester having a friction coefficient measuring function, applying a constant load with a diamond indenter on each protective film, and sliding at a constant speed. Table 4 shows the measurement results.

[0043]

[Table 4] As is clear from Table 4, all the protective films using the wear resistant coating of the present invention have a low friction coefficient. From this result and the evaluation result of Example 2, it is clear that the thermal print heads of this Example both have good durability.

Embodiment 5 Next, an embodiment of the third thermal print head of the present invention will be described.

Thermal print heads were produced in the same manner as in Example 3 and Example 4, using the sintered targets for the base film and the sintered targets for the protective film whose combinations are shown in Table 5. The rate of change in resistance of these thermal print heads and the coefficient of friction of the protective film were measured in the same manner as in Example 3 and Example 4. The measurement results are also shown in Table 5.

[0046]

[Table 5]

[0047]

As described above, according to the present invention, a base film for a heating resistor having excellent surface properties and film thickness uniformity, and
It is possible to stably provide a wear-resistant coating having low film stress and excellent sliding characteristics. Therefore, the thermal print head using the underlayer film for heat generating resistors and the abrasion resistant film (protective film) with such durability can stably obtain excellent printing performance over a long period of time. Becomes

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main configuration of a thermal print head according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... Alumina substrate 1a ... Glass glaze layer 2 ... Heating resistor base film 3 ... Heating resistor layer 4 ... Electrode conductor layer 5 ... Heating part 6 ... Protective film 7 ... Thermal print head

Claims (11)

[Claims] 1. Si-M1-ON (M1 is Al, Cr, Ti, Zr, Hf,
A sputtering target containing at least one metal element selected from Mg and Y (excluding the combination of Si-Al-ON) as a main constituent element. 2. An oxide of at least one metal element (M1 element) selected from Al, Cr, Ti, Zr, Hf, Mg and Y.
A sputtering target, which is obtained by sintering a mixture containing 1 to 45 mol% and the balance substantially consisting of silicon nitride. 3. An underlayer film for a heating resistor formed by sputtering using the sputtering target according to claim 1, wherein Si-M1-ON (excluding a combination of Si-Al-ON) is used. A base film for a heating resistor, which is contained as a main constituent element. 4. A sputtering target containing Si—Cr—ON as a main constituent element. 5. Si-Cr-M2-ON (M2 is Al, Ti, Zr, Hf, Mg
And at least one metal element selected from Y) as a main constituent element. 6. Chromium oxide in the range of 1-40 mol%, 0-
An oxide of at least one metal element (M2 element) selected from Al, Ti, Zr, Hf, Mg and Y in the range of 30 mol%,
As the total amount of the chromium oxide and the oxide of the M2 element
A sputtering target, which is obtained by sintering a mixture containing 1 to 45 mol% and the balance substantially consisting of silicon nitride. 7. A wear-resistant coating film formed by sputtering using the sputtering target according to claim 4, wherein Si-Cr-ON is contained as a main constituent element. . 8. A wear-resistant coating film formed by sputtering using the sputtering target according to claim 5, wherein Si-Cr-M2-ON is contained as a main constituent element. Film. 9. An insulating support base, a heating resistor base layer provided on the insulating support base, a heating resistor layer provided on the heating resistor base layer, and the heating resistor. A thermal head comprising a conductor layer for supplying power to the heating resistor provided on a body layer, wherein the underlayer for the heating resistor comprises the underlayer for the heating resistor according to claim 3. The thermal head is characterized by 10. An insulating support base, a heating resistor layer disposed on the insulating support base, and a conductor layer provided on the heating resistor layer for feeding power to the heating resistor. A thermal head comprising a protective film for protecting the heating resistor layer and the conductor layer, wherein the protective film is formed of the abrasion resistant coating according to claim 7 or 8. head. 11. An insulating support base, a heating resistor base layer provided on the insulating support base, a heating resistor layer provided on the heating resistor base layer, and the heating resistor. In a thermal head comprising a conductor layer for supplying power to a heating resistor provided on a body layer and a protective film for protecting the heating resistor layer and the conductor layer, the underlayer for the heating resistor is defined by: A thermal head comprising the underlayer film for a heating resistor according to claim 3 and the protective film comprising the abrasion resistant film according to claim 7 or 8.