JPH03248861A - Sputter target and abrasion resistant film as well as thermal head, which are utilizing it - Google Patents

Abstract

PURPOSE:To obtain stable sputter target by a method wherein the sputter target is constituted of a material containing the predetermined amount of at least one kind (excluding a case in which only zirconium oxide is contained) selected from titanium oxide, zirconium oxide and hafnium oxide and a balance is silicon oxide substantially. CONSTITUTION:The oxide of IVa group metal of Ti, Zr and Hf, which are contained in silicon nitride sputter target, improves the toughness of a sputter film obtained and increases the stability of composition of the target itself whereby a sputter rate is improved and the deterioration of the sputter rate due to the kind of sputter gas is prevented. The content of the sputter target is preferably within the range of 1mol%-40mol% as the total amount of oxide of the IVa group metal. When the content of the oxide of IVa group metal is less than 1mol%, the strength of an obtained sputter film is not sufficient while the content of the same exceeds 40mol%, the IVa group metal is readily separated out as a metallic constituent and there is possibility to invite the deterioration of the insulating property of the sputter film. One kind or more than two kinds of the oxides of the IVa group metal can be used by mixing them; however, the independent use of zirconium oxide should be excluded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a sputter target suitable for forming a protective film used in thermal heads, contact sensors, etc., and a wear-resistant sputter target formed using the sputter target. The present invention relates to a wear-resistant coating and a multi-head using this wear-resistant coating as a protective coating.

(Prior Art) Thermal heads have come to be widely used in various recording devices such as facsimiles and word processor printers due to their advantages such as low noise, low maintenance, and low running costs. On the other hand, various electronic devices are required to be smaller, lower in price, and lower in power consumption, and thermal heads are also desired to be small, inexpensive, and highly efficient.

As a thermal head that satisfies such demands, a thermal head using a resin having excellent heat resistance and low thermal diffusivity, such as polyimide resin, as a heat insulating layer is attracting attention.

The thermal head using a heat-resistant resin as the heat insulating layer described above has, for example, a structure as shown below.

That is, in the above thermal head, a heat insulating layer made of polyimide resin or the like is provided on a metal substrate, and a heating resistor layer, an individual electrode, and a conductive layer serving as a common electrode are sequentially formed on this heat insulating layer. -ON% S13 N
4. It is constructed by coating with a protective film made of StC or the like.

As the above-mentioned protective film, an anti-oxidation film and a wear-resistant film may be provided as separate layers, or an adhesive layer may be provided as necessary. In addition, in order to protect the heat insulating layer from ashing processing, etc., to facilitate resistance value control during the formation of the resistance layer, and to further improve wire bonding properties, a layer of 5i02, SIN% StC, etc. is used between the heat insulating layer and the heating resistor layer. A base layer is also provided.

It has been confirmed that such a thermal head can sufficiently withstand the operation of the thermal head in terms of heat resistance and bonding force. However, as a result of running tests incorporating this thermal head into devices such as facsimile machines, we found that
Abnormal resistance value changes were observed during running, and many phenomena were observed that affected printing.

A detailed investigation of the singular point that caused such an abnormal change in resistance revealed that foreign matter such as dust caught between the thermal head and the thermal paper caused cracks in the thermal head's protective film. It has been found that a singularity occurs when a crack reaches the heating resistor. Moreover, when a conventional alumina substrate with a glazed glass layer is used as a high-resistance substrate, or when a metal substrate with a glass layer is used as a high-resistance substrate, this phenomenon occurs even with a thermal head having the same other configurations. The present inventors found that this phenomenon was not observed and was unique to the case where a resin was used as the heat-retaining layer.

This is because when a glass layer is used as a heat insulating layer, the glass layer has high hardness and only deforms to the same extent as the protective film, which prevents local deformation of the protective film.
Resins such as polyimide have high elasticity and deformability that is significantly greater than that of the protective film, so when a localized concentrated load is applied to the protective film, the heat insulating layer made of resin will deform significantly.
This is thought to be because the protective film cannot follow this deformation and breaks.

For this reason, various protective film materials have been studied, but Ta205 and 5i02 have poor hardness, and
j3N 4.5j CSAI203 etc. have poor toughness,
The inventors of the present invention have found that both of them are susceptible to cracking and cannot withstand practical use.

On the other hand, as a protective film material that can prevent the occurrence of boat fishing rack,
High hardness and high toughness 5t-
Sialon membranes mainly composed of AI-0-N are attracting attention.

However, the above-described sialon film has a problem in that the sputtering rate is low when sputtering is performed in an Ar atmosphere, and A1 is likely to precipitate as a metal component in this atmosphere, resulting in a decrease in insulation properties.

The problem that this person 1 precipitates is 5% to 10% in Ar.
Although this can be improved by adding a certain amount of O2 or N2, the sputtering rate further decreases, causing an increase in cost.

(Problems to be Solved by the Invention) As mentioned above, in a thermal head, by using a resin having a low thermal diffusivity such as polyimide resin as a heat insulating layer, it has excellent thermal efficiency, can be bent, and can be easily miniaturized. On the other hand, since the resin layer is soft, there is a large difference in the amount of deformation between the resin layer and the protective film when local stress is applied to the protective film due to entrainment of dust, etc. There is a problem in that when cracks occur and reach the heating resistor, the resistance value becomes abnormal and the printing performance deteriorates.

Such problems occur not only in thermal heads but also in solid-state devices such as fully contact type sensors.

The present invention was made to address these conventional problems, and it is possible to form a highly reliable protective film that does not generate cracks even when local stress is applied, and has a long lifespan. To provide a stable sputtering target that causes almost no change in target composition and sputtered film properties over time, a wear-resistant coating formed using the same, and a thermal head with excellent printing performance stability. The purpose is

[Structure of the Invention] (Means for Solving the Problems) That is, the first sputter target in the present invention is made of at least one selected from titanium oxide, zirconium oxide, and hafnium oxide (however, in the case of using only zirconium oxide, (excluding) 1m.

The second Suba/Ivy target contains 1 mol% of at least one selected from titanium oxide, zirconium oxide, and hafnium oxide. ~
40 mol%, and 0.05 mol% to 10 mol% of at least one selected from yttrium oxide and aluminum oxide (excluding the use of zirconium oxide alone in the case of yttrium oxide alone),
It is characterized in that the remainder essentially consists of silicon nitride.

Further, the wear-resistant coating of the present invention is a wear-resistant coating made of a sputtered film formed using the above sputter target, and is characterized in that at least a part of its structure is in an amorphous state.

Sarani, the thermal head of the present invention includes a support base having a heat-resistant resin layer, a heating resistor layer disposed on the heat-resistant resin layer, and a heating resistor layer provided on the heating resistor layer. A thermal head having an electrode conductor layer for power supply and a protective film for protecting the heating resistor and the electrode conductor layer is characterized in that the protective film is constituted by the above-described wear-resistant coating.

The IVa group metal oxides of Ti, Zr and Hf' contained in the first silicon nitride sputtering target are:
By increasing the toughness of the resulting sputtered film and increasing the compositional stability of the target itself, it improves the sputtering rate and prevents the sputtering rate from decreasing due to the type of sputtering gas, and its content is IV
1IIlo1% to 40 as the total amount of oxides of group a metals
The range is mol%.

If the content of these IVa group metal oxides is less than 1 mol%, the resulting sputtered film will not have sufficient strength, while if it exceeds 40 mol%, the IVa group metal will tend to precipitate as a metal component, and the sputtered film will have insufficient strength. This may lead to a decrease in insulation properties. A more preferable content is 5 mol%
It is in the range of ~20 mol%.

The above IVa group metal oxides can be used alone or in combination of two or more, but the present invention excludes the use of zirconium oxide alone.

In addition, yttrium oxide and aluminum oxide contained in the second silicon nitride-based sputtering target can be used in combination with the above-mentioned IVa group metal oxide to further enhance the above-mentioned effects and to make the target itself easier to manufacture. The total content of yttrium oxide and aluminum oxide is 0.05 m
It ranges from ol% to lomol%.

Further, the content of the IVa group metal oxide in this second sputter target is in the range of 1 mol% to 40rIlo1%, similar to the above first sputter target, and the content of yttrium oxide and aluminum oxide is in the range of 1 mol% to 40rIlo1%, as in the above-mentioned first sputter target. It is determined by considering the content of oxides of group IVa metals, but the more preferable content is 0.
．． It is in the range of 3 mol% to 1 mol%.

The reasons for limiting the contents of yttrium oxide and aluminum oxide are as follows.

That is, if their content is less than 0.05 mol%, the strength improvement effect of the resulting sputtered film will not be sufficient;
On the other hand, if it exceeds 10 mol %, Y and AI tend to precipitate as metal components, which may lead to a decrease in the insulation properties of the sputtered film.

The above effects can be obtained by containing at least one of yttrium oxide and aluminum oxide, but it is more preferable to contain both of them. Note that the present invention excludes the use of zirconium oxide alone in the case of yttrium oxide alone.

The specific composition of the sputter target of the present invention is as follows:
For example, the compositions shown in Table 1 are exemplified.

(The following is a blank space) 1 2 The sputter target of the present invention is produced by a sintering method such as a normal pressure sintering method, an atmosphere pressure sintering method, a hot press method, or a HIP method, for example, like a normal ceramic sintered body. be done.

The sputter target of the present invention obtained by such a sintering method has a sintered density of 60% to 95% of the theoretical density.
It is preferable to set it as the range of. This is because the sputtering rate can be improved by making the sintering density relatively low. Furthermore, if the sintered density is less than 60% of the theoretical density, the brazing filler metal used for bonding with the backing plate will easily penetrate into the sintered body and the workability will decrease, and if it exceeds 95%, the sputter rate will be reduced. This is because not only does this lead to a decrease in the performance of the backing plate, but also thermal stress cracking is likely to occur due to the difference in thermal expansion with the backing play 1.

Further, the wear-resistant coating of the present invention is made of a sputtered film formed using the above-described sputtering target of the present invention, and at least a portion of its structure is amorphous.

Such an amorphous sputtered film exhibits excellent toughness and high hardness, making it suitable as a wear-resistant coating.

The composition of the wear-resistant coating of the present invention is the same as that of the above-mentioned target, but the composition ratio differs depending on sputtering conditions and so on, and therefore does not necessarily match.

The above-mentioned wear-resistant coating is formed by sputtering using the sputter target of the present invention under normal sputtering conditions. An inert gas is used as the sputtering gas, but argon gas containing about 5% to 10% of oxygen and nitrogen is used to prevent Group A metals, Y, AI, etc. from precipitating as metal components. It is preferable.

The above-mentioned wear-resistant coating has high hardness, excellent film breaking strength, and excellent adhesion to the adherend substrate, and is therefore suitable as a protective film for thermal heads, contact type sensors, and the like.

The thermal head of the present invention uses the above-mentioned wear-resistant coating of the present invention]4 as a protective film of a thermal head that uses a resin layer made of polyimide resin or the like as a heat insulating layer. Note that the above-mentioned wear-resistant coating also functions as an oxidation-preventing film for the heating resistor layer and the electrode conductor layer.

(Function) The sputter target of the present invention contains silicon nitride as a main component, and oxides of group IVa metals, yttrium oxide, aluminum oxide, and the like.

Here, when sputtering is performed using a sputter target having such a composition, the high hardness of the sputtered film mainly composed of silicon nitride is maintained, and the metal components such as IVa group metals and Y1A+ are sputtered. Since it is appropriately dispersed in the film, the toughness of the sputtered film is greatly improved, giving it excellent wear resistance and preventing the occurrence of cracks. In addition, the sputter target of the present invention has a high sputter rate, and even when Ar gas containing 02 or N2 is used as the sputter gas, the sputter rate hardly decreases, so the sputter target has excellent properties in a short time. A membrane is obtained.

Further, the sputtered film formed using the above sputter target is in an amorphous state and has increased toughness, so that a high quality wear-resistant coating can be obtained.

Furthermore, by using this wear-resistant coating as a protective film for a thermal head that has a resin heat-insulating layer, cracks in the protective film that occur due to the deformability of the resin layer are prevented, so it can be used stably for a long period of time. A thermal head capable of

(Example) Examples of the present invention will be described below.

Example 1 T with an average particle size of 0.03 μm was added so that 5 mol% of TiO2 was contained in Si3N4 powder with an average particle size of 0.5 μm.
Add iO2 powder and mill in ethanol by ball milling.
After mixing and dispersing for 2 hours, the mixture was dried to produce a raw material powder.

Next, the raw material powder was hot-press sintered in an N2 atmosphere at 1775° C. for 2 hours, and then diamond-cut to obtain a sputter target with a diameter of 203 mm and a thickness of 8 mm.

Using the sputtering target thus obtained, 6 Then, a protective film for the thermal head was formed.

FIG. 1 is a diagram showing the structure of the thermal head used in this example, which is manufactured, for example, by the method shown below.

First, for example, a thickness of 0.5 m containing 18% by weight of Cr.
After leveling the metal substrate 1 made of a Pe alloy of about m,
After cutting to specified dimensions and scraping, degrease and wash in an organic solvent, and immerse in dilute sulfuric acid maintained at 50°C to 70°C to remove the oxide layer formed on the surface and clean the surface. Activation treatment is performed to microscopically destroy.

Next, the polyamic acid is adjusted to a predetermined viscosity using a solvent such as N-methyl-2-pyrrolidone, and the metal substrate is
250° C. for 1 hour at 50°C, 30 minutes at 80°C, then 30 minutes at 120°C using a baking furnace.
℃ for 1 hour and 450℃ for 1 hour to remove the solvent component and proceed with the dehydration cyclization reaction to form a film. form.

7 Next, using 5iHn gas, N2 gas, SiH4 gas, and CH4 gas on the heat insulating layer 2, the substrate temperature was set to 150.
SiN is continuously deposited by plasma CVD at temperatures between ℃ and 300℃.
A base layer 3 consisting of a layer 31 and a Si0 layer 32 is formed.

Next, a heating resistor layer 4 made of Ta-8i02 and an electrode conductor layer made of AI are formed and patterned by wet etching or dry etching so that openings that will become heating parts 5 are provided, and individual electrodes 6 and A common electrode 7 is formed.

After that, so that the heat generating part 5 is at least covered,
A protective film 8 is formed by sputtering. The thickness of the protective film 8 is usually 1 μm to 7 μm, preferably 2 μm to 4 μm.

Then, in forming the protective film 8, using the sputtering target of this example, high-frequency magnetron sputtering was performed at 2 kW in Ar gas containing 5% O2.
A protective film 8 was formed by sputtering under the following output conditions, and the thermal head of this example was obtained.

8 Using the thermal head obtained in this way, characteristics evaluations were performed not shown below.

■ Hardness was measured using an ultra-fine Knoop hardness tester for thin films.

(2) Membrane destruction strength was measured using a scratch tester equipped with a sensor that detects AE (acoustic emission) generated at the time of membrane destruction.

In addition, the sputtering rate when forming the protective film was measured. These results are shown in Table 2.

Examples 2 to 20 Sputter targets having the compositions shown in Table 2 were prepared under the same conditions as in Example 1, and protective films 8 were formed in the same manner as in Example 1 using these sputter targets. A thermal head was obtained for each. The starting material for the sputter target is Z with an average particle size of 0.03 μm.
rO2 powder, average particle size 0.03. HfO2 powder of cz m, average particle size 1. ．． 0μm Y2O3 powder, average particle size 0
．． 1 μm Al2O3 powder was used in each case.

] 9 The characteristics of these thermal heads were evaluated in the same manner as in Example 1. The results are also shown in Table 2.

Comparative Examples 1 to 4 Si3N, 4 (Comparative Example 1), 5iON (Comparative Example 2), l
5i02/Ta205 (Comparative Example 3), Si3
Sputter targets made of N4-10wt%Al203 (Comparative Example 4) were prepared, and a thermal head having a protective film formed using these targets was manufactured under the same conditions as in Example 1, and its characteristics were compared to Example 1. Measurement was carried out under the same conditions as 1.

The results are shown in Table 2 together with the results of Examples.

(The following is a blank space) 1 As is clear from the above results, the protective film formed using the sputter target of the present invention had excellent strength, and was able to prevent the occurrence of cracks even when resin was used as the heat insulating layer. .

Furthermore, the sputtering target of the present invention has a high sputtering rate, making it possible to reduce costs in the protective film forming process.

Further, even after film formation over a long period of time, there was no change in the composition of the target or the characteristics of the sputtered film.

Although this embodiment describes a thermal head, the sputter target of the present invention is not limited to the above-mentioned thermal head, but can also be used to form a protective film for a thermal head using an Al2O3 substrate, or a protective film for a magneto-optical disk. It is also effective for

[Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a sputtered film with high hardness and high toughness, thereby making it possible to provide a highly reliable wear-resistant coating. In addition, a thermal head using this wear-resistant coating as a protective film can suppress cracks in the protective film, and therefore can exhibit stable and excellent printing performance.

Further, since the sputter target of the present invention has excellent compositional stability, etc., it also has an excellent sputtering rate, and thereby costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a thermal head using the wear-resistant coating of the present invention as a protective film. 1...Metal substrate, 2...Heat insulation layer, 3.
... Base layer, 4 ... Heat generating resistor, 5 ...
... Heat generating part, 6 ... Individual electrode, 7 ...
...Common electrode, 8...Protective film.

Claims (4)

[Claims] (1) Contains 1 mol% to 40 mol% of at least one selected from titanium oxide, zirconium oxide, and hafnium oxide (excluding the case of zirconium oxide alone), and the remainder consists essentially of silicon nitride sputter target. (2) 1 mol% to 40 mo of at least one selected from titanium oxide, zirconium oxide, and hafnium oxide
1% and at least one selected from yttrium oxide and aluminum oxide (excluding the use of zirconium oxide alone in the case of yttrium oxide alone) 0.0
5 mol % to 10 mol %, and the remainder substantially consists of silicon nitride. (3) A wear-resistant film comprising a sputtered film formed using the sputter target according to claim 1 or 2, characterized in that at least a part of its structure is in an amorphous state. (4) a supporting base having a heat-resistant resin layer; a heating resistor layer disposed on the heat-resistant resin layer; and an electrode conductor layer provided on the heating resistor layer for supplying power to the heating resistor; A thermal head comprising a protective film for protecting the heat generating resistor and the electrode conductor layer, wherein the protective film is constituted by the wear-resistant coating according to claim 3.