JPH0126347B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a target for a thermal print head.

There are various facsimile reception and recording methods, but electrostatic recording, thermal recording, inkjet recording, etc. are considered promising when considering future prospects. Among these, the fixed scanning multi-element thermal recording method was developed as a printer technology, and has attracted attention as a new recording method because it does not require processes such as developing and fixing, and does not generate odor gas like discharge breakdown recording. ing.

By the way, there are three types of thermal recording heads: thin-film type, thick-film type, and semiconductor type, and the thin-film type in particular has advantages such as good thermal response and high heat resistance of the film. 1 is constructed as shown in cross section. The heat-sensitive recording head is formed by vacuum evaporating a heating resistor 3 on a ceramic substrate 1 via a heat insulating layer 2, and then forming it into a desired shape by photoetching. Next, a lead wire 4 is provided, and a resistive protective film 5 and an abrasion resistant layer 6 are further provided.
A thin film type thermal head is manufactured by sequentially providing the following.

Here, the heating resistor 3 is formed on the heat insulating layer 2 of the ceramic substrate 1 by sputtering. The targets used for this sputtering include:
For example, the metal tantalum (Ta) is known. A thin film is formed by reactive sputtering in nitrogen gas using this Ta as a target. However, it is difficult to control the film thickness, the reproducibility and uniformity of resistance values deteriorate, and in terms of characteristics, the power density increases, making it easier to break down. As another example, as a sputter target, as shown in _FIG .
A material covered with Ta foil 22 is used.
23 is a cooling metal jig, 24 is packing, 25
is a support stand.

However, this prior art also has the following drawbacks because it uses a target as shown in FIG.

(1) Although the target surface is formed so that the Ta surface and the SiO ₂ surface are made as small a unit as possible, since the unit is still a fairly large area, only the Ta surface can be seen from the Ta surface. _SiO2
Since only Si--O is ejected from the surface, the distribution of sputtering ions becomes uneven, and this influence cannot be avoided on the attached film, resulting in insufficient microuniformity of the distribution of Ta and SiO ₂ . For this reason, it is unsuitable for use as a constant voltage application type, high-speed heat-generating, low-resistance material, and has poor uniformity, resulting in the occasional occurrence of dots that break down in a short period of time.

(2) Ta foil had a higher spatter rate, so it ran out faster and had a shorter lifespan. In particular, the electric field was concentrated at the edges, corners, and protrusions, causing the Ta foil to wear out more quickly.

(3) For the above reasons, the ratio of Ta and SiO ₂ varies both two-dimensionally and three-dimensionally, making it difficult to control and making it difficult to obtain a uniform, high-quality thin film resistor.

In order to further improve this technique, a target was discovered in which tantalum (Ta) and silicon dioxide (SiO ₂ ) powders were mixed in an appropriate ratio and then sintered using a hot press method. This target is Ta
Because SiO ₂ and SiO 2 are uniformly dispersed, the thin film obtained by sputtering is uniform, stable, and high quality. However, as mentioned above, this sintered target is usually manufactured using the hot press sintering method, and since the target is thinner than its area, the same pressure is applied to the entire surface of the sintered body. It is difficult to produce a uniform sintered body that is difficult to coat. In particular, variations in density in each part of the sintered body are unavoidable because the problems of shape and manufacturing method work synergistically. Furthermore, Ta and SiO ₂ are relatively easy to undergo a phase reaction, and TaSi ₂ , Ta ₅ Si ₃ , αTa 2 O ₅ , βTa _{2 O 5} , etc. change depending on the reaction state, which is directly related to the density unevenness in each part of the sintered body. This results in the production of various compounds. When sputtering is performed using a target whose density or constituent phase varies depending on the location, the resistance value, film thickness, etc. of the formed thin film become unstable, resulting in a very low yield as a product.

The present invention was devised in view of this point, and an object of the present invention is to provide a method for manufacturing a sintered target for a thermal print head having a uniform density and the same constituent phase.

In other words, a uniform sintered body is produced by cold molding a mixed powder of Ta and SiO ₂ in an appropriate ratio and then sintering it under pressure in a non-oxidizing atmosphere without applying pressure. be. According to the method of the present invention, no pressure is applied during sintering that causes non-uniformity, so in the hot press sintering method, the density and constituent phases vary greatly depending on the location of the target (for example, the density differs from the average value). (with a variation of ±20%), whereas with the method of the present invention, almost no variation is observed.
Furthermore, the resistance value, film thickness, etc. of the thin film obtained by sputtering using this target are the same as those obtained using the hot press sintering method, but there are no variations that greatly affect the yield of the product, and it is very good. I got good results. Here, the ratio of Ta to _SiO2 is Ta is 50 to 63
A desirable mol % is outside this range, and the resistance value of the sputtered thin film is practically unfavorable.

The present invention will be explained below with reference to Examples.

Example 1 Metallic tantalum (Ta) powder with an average particle size of 2.5 μm
786 g and 214 g of silicon dioxide (SiO ₂ ) powder with an average particle size of 1.2 μm were mixed for 15 hours using a synthetic resin-coated pot and ball. 140mm x 500g of this mixed powder
Cold-formed to 6 mm, then in an argon (Ar) atmosphere.
Sintered at 1400℃ for 5 hours under normal pressure. The porosity of the obtained sintered body was 29%, and the variation in each part of the sintered body was 0.5%.
It was within Furthermore, when the constituent phases were identified by X-ray diffraction, they were found to be Ta, SiO ₂ , TaSi ₂ , Ta ₂ O ₅ , etc., which were the same as those of the hot press sintering method, but no differences were observed in the constituent phases depending on the location. The amounts produced were almost the same. The resistance value, film thickness, etc. of the thin film obtained by sputtering using this sintered body as a target were qualitatively the same as those of the hot press sintering method, but were completely uniform and good results were obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the structure of a thin film thermal head. FIG. 2 is a perspective view showing a conventional example of a sputter target. 1... Ceramic substrate, 2... Heat insulation layer, 3...
Heat generating resistor, 4...Lead wire, 5...Resistor protective film, 6...Abrasion resistant layer.

Claims (1)

[Claims] 1. A method for manufacturing a target for a thermal print head in which a heat generating resistor thin film is formed by sputtering a target containing tantalum and silicon oxide in an argon gas atmosphere. Cold-formed and then heated in non-oxidizing atmosphere at 1100 °C
A method for producing a target for a thermal print head, characterized by pressureless sintering at a temperature of ~1600°C.