JP2825209B2 - Manufacturing method of thin film thermal head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin film thermal head used in a thermal printer.

[Conventional technology]

It has a plurality of heating resistors arranged in a line, and by selectively energizing any one of the heating resistors, the thermal recording paper is partially colored or the ink on the ink ribbon is partially melted. Thermal heads that perform printing by transferring the data to recording paper and printing are widely known. In such thermal heads, thin-film thermal heads are overwhelmingly used than thick-film thermal heads.

The above-described thin-film thermal head and its manufacturing method are:
Generally, as shown in FIG. 2, a glaze layer 2 made of glass or the like for heat storage is laminated on an insulating substrate 1 made of alumina or the like by baking or the like. On the glaze layer 2, so that a plurality of heat-generating resistor 3 made of a bad Ta-SiO ₂ having conductivity, aligned in a straight line by performing etching photolithography after being totally laminated Is formed. A common electrode 4A and an individual electrode 4B for supplying electricity to each heating resistor 3 are formed on the upper surface on both sides of each heating resistor 3, respectively, and are provided between the common electrode 4A and the individual electrode 4B. The heat-generating resistor 3 at the portion exposed in FIG. 3 is a heat-generating dot 3A that actually contributes to printing. The glaze layer 2, the heating resistor 3, the common electrode 4A, and the individual electrodes 4B
Is covered with a protective layer 5.

In the above-described thermal transfer printer using the conventional thin-film thermal head, the thin-film thermal head is pressed against the recording paper via the ink ribbon, and the individual electrodes 4B corresponding to the desired heating resistor 3 based on predetermined print information. , The heating resistor 3 generates heat, and the ink of the ink ribbon is partially melted and transferred to the recording paper, whereby a predetermined printing can be performed on the recording paper.

[Problems to be solved by the invention]

When the heating resistor 3 is formed on the glaze layer 2 described above, conventionally, a material such as Ta—SiO ₂ is formed on the glaze layer 2 by sputtering in a vacuum chamber. In this case, the electric resistance value of the heating resistor 3 varies from one production lot to another. This was mainly due to the fact that the atmosphere during film formation slightly fluctuated for each production lot. That is, since O atoms are dissociated from H ₂ O molecules adsorbed on the inner wall of the vacuum chamber during film formation and are taken into the heating resistor layer, the desired resistance value of the heating resistor 3 can be reduced. Misalignment has occurred.

As one of the methods for reducing the variation in the electric resistance value of the heating resistor 3 for each manufacturing lot, an undercoat layer made of an electrically insulating material is formed on the glaze layer 2 before forming the heating resistor layer. It is possible to film. By doing so, most of the O atoms dissociated from the inner wall of the vacuum chamber during sputtering are taken into the undercoat layer, so that the ratio of the heat generating resistor 3 itself affected by the O atoms is reduced. Therefore, it is possible to reduce the variation of the electric resistance value between the production lots.

However, in order to prevent the variation of the electric resistance value of the heating resistor 3 by forming the undercoat layer on the glaze layer 2 before forming the heating resistor layer, it is necessary to use the undercoat layer and the undercoat layer. If the interface between the heating resistor 3 and the heating resistor 3 becomes insufficient, and if the electrodes 4A and 4B are energized with a high voltage, the insulation of the undercoat layer may be destroyed. Furthermore, a sputter target for the undercoat layer must be used, and the process is complicated.

Further, as another method for preventing variation in the electric resistance value of the heating resistor 3 for each manufacturing lot, it is conceivable to form the heating resistor layer thickly over a sufficient time.
By doing so, the above-mentioned O atoms are almost taken into the lower part of the heat generating resistor 3, so that the heat generating resistor 3 and the upper part through which a large amount of current flows are hardly affected by the O atoms. Variations in the electrical resistance value of the heating resistor 3 between them can be reduced.

However, in this case, since the thickness of the heating resistor layer is large, patterning of the heating resistor 3 is difficult, and the adhesion is deteriorated due to an increase in stress in the film of the heating resistor layer.
There is a problem such as an increase in the throughput time in the manufacturing process, and therefore, the upper limit of the thickness of the heating resistor layer has been determined naturally.

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned problems of the prior art, and efficiently and stably prevents a variation in the electric resistance value of a heating resistor from one production lot to another in a simple production process. It is an object of the present invention to provide a method for producing the same.

[Means for solving the problem]

In order to achieve the above object, a method for manufacturing a thermal head according to claim 1 of the present invention is a method for manufacturing a thin film thermal head in which a heating resistor having two layers, an upper layer and a lower layer, is formed by sputtering. A sputter using Ar gas using the same kind of material and a sputter target having the same composition ratio, and when forming the lower heating resistor, when forming the upper heating resistor. Sputter deposition with a larger sputter gas pressure than
During the sputtering, while dissociating the H ₂ O molecules adsorbed on the inner wall of the vacuum chamber of the sputtering apparatus, O atoms generated by the dissociation are introduced into the film of the lower heating resistor, and then the upper layer is heated. It is characterized in that the heating resistor is formed by sputtering thicker than the lower heating resistor.

Further, the method for manufacturing a thermal head according to claim 2 comprises:
The material of the sputter target is Ta and SiO ₂ .

Further, the method of manufacturing a thermal head according to claim 3 is a method of manufacturing a thin-film thermal head in which a heating resistor having two layers, an upper layer and a lower layer, is formed by a sputtering method. Sputtering using an Ar gas using a sputtering target having a sputtering gas pressure greater than when the lower heating resistor is formed than when the upper heating resistor is formed. During the sputtering, H atoms adsorbed on the inner wall of the vacuum chamber of the sputtering apparatus were dissociated, and O atoms generated by the dissociation were taken into the film of the lower heating resistor while dissociating H ₂ O molecules. Later, the upper thermal resistor is sputter-deposited thicker than the lower thermal resistor.

Furthermore, a method of manufacturing a thermal head according to claim 4 is characterized in that the material of the sputter target is Ta and SiO ₂ .

(Operation)

According to the thermal head manufactured by the method of manufacturing a thin film thermal head of the present invention having the above-described configuration, the variation in the electric resistance value due to the change in the atmosphere in the vacuum chamber during the film formation between the manufacturing lots is: It will be absorbed by the lower layer film formation. That is, the sheet resistance of the upper layer is
Assuming that R ₁ , the sheet resistance of the lower layer is R ₂ , and the rate of change of the electric resistance between the production lots is α, the combined sheet resistance R of the upper and lower layers of the heating resistor is R = (1 + α) R ₁ R ₂ / [R ₁ + (1 + α) R ₂ ]. In the present invention, in particular, since R ₁ <R ₂ , R ≒ R ₁ , and the combined area resistance value R is not much affected by the rate of change in the electrical resistance value in the production lot.

〔Example〕

Hereinafter, the present invention will be described with reference to embodiments shown in the drawings. The same components as those of the above-described conventional device are denoted by the same reference numerals in the drawings, and description thereof will be omitted.

FIG. 1 shows an embodiment of a method of manufacturing a thin-film thermal head according to the present invention, in which a glaze layer 2 formed on an insulating substrate 1 has a lower layer 3a formed on the glaze layer 2. And a heating resistor 3 including an upper layer 3b formed on the lower layer 3a. Of these, the lower layer 3a is for stabilizing the atmosphere in the vacuum chamber at the time of sputtering, and the lower layer 3a is about 500 mm in this embodiment.
Is formed. The upper layer 3b formed on the lower layer 3a is a main heat generating layer that generates heat when energized,
The upper layer 3b is formed to a thickness of about 2500 ° which is about 5 times that of the lower layer 3a.

The formation of the lower layer 3a and the upper layer 3b is performed by sputtering, respectively.
And the formation of the lower layer 3a.

First, the sputtering of the lower layer 3a is performed by setting the target to Ta-SiO ₂ ,
Sputtering gas Ar (pressure 6 × 10 ¹ Pa), RF power 1.6KW
Perform as On the other hand, in the sputtering of the upper layer, the target was made of the same material and composition ratio of Ta—SiO ₂ as in the lower layer 3a, the sputtering gas was Ar (pressure 1 × 10 ⁻¹ Pa),
The RF power is set to 1.6 KW and is performed on the lower layer 3a. After that, a plurality of heating resistors 3 having a predetermined shape are formed by etching or the like.

When the lower layer 3a and the upper layer 3b are formed under such conditions, the specific resistance of the lower layer 3a is about 60 mΩ-cm, and the specific resistance of the upper layer 3a is about 30 mΩ-.
cm. Therefore, the sheet resistance of the lower layer 3a is about 10 times that of the upper layer 3b, and when the thermal head is driven,
More than 90% of the input power is consumed in the upper layer 3b.

According to such an embodiment, the lower layer 3a and the upper layer 3b constituting the heating resistor 3 are formed by first forming the lower layer 3a and then forming the upper layer 3b. 3
Dissociation of O atoms in the H ₂ O molecules adsorbed on the inner wall of the vacuum chamber during sputtering, which causes a variation in the electric resistance value of, is almost performed during the formation of the lower layer 3a and is taken in Will be. By the way, over 90% of the input power when driving the thermal head is consumed in the upper layer 3b, and in the lower layer 3a, less than 10% of the input power is consumed. Even if it is taken in, it does not significantly affect the overall electric resistance value of the heating resistor 3.

Therefore, it is possible to form the heating resistor 3 in which the electric resistance value does not vary between manufacturing lots.
For example, the variation of the electric resistance value of the heating resistor 3 between the manufacturing lots, which was about ± 10.0% in the past, can be reduced to about ± 5.4%.

Moreover, since the lower layer 3a and the upper layer 3b are formed of the same material, there is no problem in the adhesion between the lower layer 3a and the upper layer 3b, and both the lower layer 3a and the upper layer 3b are formed by a single sputter target. Since it is formed, the manufacturing process can be simplified.

Note that the present invention is not limited to the above-described embodiments, and various modifications can be made as necessary.

For example, in the above-described embodiment, the same material is used up to the composition ratio, and the power consumption in the upper layer 3b is increased by increasing the thickness of the upper layer 3b from the lower layer 3a. By changing only the composition ratio in the same manner, it is possible to make the lower layer 3a electrically higher in resistance than the upper layer 3b so that the electric resistance value of the heating resistor 3 does not vary between manufacturing lots. As an example, the material of the upper layer 3b and lower 3a of the heating resistor 3 and Ta-SiO _2, Ta and the ratio of the upper layer 3b of SiO ₂ 1: While a 1, the lower layer 3a is 2: 3 As a result, the electric resistance value of the lower layer 3a can be increased.

〔The invention's effect〕

As described above, according to the method of manufacturing a thin-film thermal head according to the present invention, the thin-film thermal head is efficiently and stably prevented in a simple manufacturing process so as to prevent the variation of the electric resistance value of the heating resistor in each manufacturing lot. It has an excellent effect that a thermal head can be manufactured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a thin film thermal head according to the present invention, and FIG. 2 is a longitudinal sectional view showing a conventional thin film thermal head. 1 ... insulating substrate, 2 ... glaze layer, 3 ... heating resistor, 3A ... heating dot, 3a ... lower layer, 3b ... upper layer, 4A ...
... common electrode, 4B ... individual electrode, 5 ... protective layer.

Claims (4)

(57) [Claims] In a method of manufacturing a thin film thermal head in which a heating resistor composed of an upper layer and an upper layer is formed in the order of a lower layer and an upper layer by sputtering, a sputter target having the same material and the same composition ratio is used. Used, sputtering using Ar gas, when forming the lower layer heating resistor, by sputtering with a larger sputter gas pressure than when forming the upper layer heating resistor ,
During the sputtering, while dissociating the H ₂ O molecules adsorbed on the inner wall of the vacuum chamber of the sputtering apparatus, O atoms generated by the dissociation are introduced into the film of the lower heating resistor, and then the upper layer is heated. A method for manufacturing a thin film thermal head, wherein a heating resistor is formed by sputtering to be thicker than the lower heating resistor. 2. The method according to claim 1, wherein the material of the sputter target is Ta and SiO ₂ . 3. A method of manufacturing a thin-film thermal head in which a heating resistor consisting of two layers, an upper layer and a lower layer, is formed in the order of a lower layer and an upper layer by sputtering, wherein sputter targets having the same kind of material and different composition ratios are used. In the sputtering using Ar gas, when forming the lower heating resistor, by sputtering with a larger sputtering gas pressure than when forming the upper heating resistor,
During the sputtering, while dissociating the H ₂ O molecules adsorbed on the inner wall of the vacuum chamber of the sputtering apparatus, O atoms generated by the dissociation are introduced into the film of the lower heating resistor, and then the upper layer is heated. A method for manufacturing a thin film thermal head, wherein a heating resistor is formed by sputtering to be thicker than the lower heating resistor. 4. The method according to claim 3, wherein the material of the sputter target is Ta and SiO ₂ .