JPH07157871A - Sputtering target - Google Patents

Abstract

PURPOSE:To produce a sputtering target small in the compositional deviation between a target and a film, capable of forming a film having a uniform compsn. and high specific resistance and capable of increasing the film forming rate and the adhesion of the film. CONSTITUTION:This is a sintered target contg. at least niobium, silicon and oxygen as constituting elements, and in which the porosity is regulated to the range of 1 to 30%. The sputtering target may furthermore contain carbon, Ta, Fe, Cr, Al, W, Mo, Re, Ru, Ni or the like. By this sputtering target, a film resistor with high specific resistance small in the dispersion of sheet resistance and having high adhesion can be obtd. and is utilized, e.g. as the exothermic resistor 4 of a thermal print head.

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 film resistor.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer recording apparatus using a thermal printer head has been used as a recording apparatus incorporated in a facsimile machine, a copying machine, a ticket vending machine, etc., by taking advantage of low noise, low maintenance and the like. There is. In such a thermal printer head, a cermet thin film, such as a Ta-SiO ₂ resistance film, which can obtain a high specific resistance, has been put into practical use as a heating resistor that generates heat and melts a print medium.

By the way, for the Ta-SiO ₂ cermet resistance film as described above, for example, sputtering film formation using a sintered target containing Ta component and SiO ₂ component or Ta target and SiO ₂ target is used. Although it is formed by multi-source sputter deposition, etc., since the sputtering emission angle between Ta and Si is greatly different, the composition of the target and the film are likely to vary due to the subtle difference in the sputtering conditions, and the film composition can be controlled. There was a problem that it was difficult. Further, because of the above-mentioned reasons, the composition in the film is likely to be non-uniform, so that the sheet resistance in the film is likely to vary, and the reproducibility of the resistance value is poor.

In order to solve such a problem of the conventional cermet-based resistance film, the present applicant has previously used a metal component as a metal component.
We have proposed Nb-SiO _x based sputtering targets and film resistors using Nb (including Nb alloys)
3-811328 gazette). The density of Nb is as small as about 1/2 of Ta, which is close to the sputter emission angle of Si, so the compositional deviation between the target and the obtained film can be made small, and the composition of the obtained film can be made uniform. In addition, it is possible to suppress variations in the sheet resistance value in the film.

The Nb-SiO _x cermet resistance film as described above can be formed by sputtering film formation using, for example, a sintered target containing Nb component and SiO ₂ component. Further, the density of the sintering target is generally a high density close to the theoretical density. However, in sputter film formation using an Nb—SiO _x system sintering target having a theoretical density close to this, there is a problem that it is difficult to obtain a sufficient film formation rate and the film formation efficiency is low.
In addition, Nb-SiO _x formed using a conventional sintering target
The cermet resistance film of the system does not have sufficient adhesion to the film-forming substrate, and may cause a problem that the heating resistor peels off, for example, in a thermal print head, which reduces the printing characteristics and life of the thermal print head. It was a factor.

[0006]

[Problems to be Solved by the Invention] As described above, Nb-S
Although the iO _x cermet resistance film has the advantage that the deviation between the target composition and the film composition can be reduced, and a film resistor having excellent composition and sheet resistance uniformity can be obtained. However, in the conventional sintering target, there have been problems that the film forming speed is slow and the adhesion of the obtained film is insufficient.

The present invention has been made in order to solve such a problem, and it is possible to form a film having a high resistivity with a uniform composition and a small composition deviation between a target and a film, and to form a film. It is an object of the present invention to provide a sputtering target capable of increasing the speed and the adhesion of a film.

[0008]

A sputtering target of the present invention is a sintering target containing niobium, silicon and oxygen as at least constituent elements,
The porosity is characterized in the range of 1 to 30%. In the above sputtering target, carbon is contained as a constituent element, and further, at least one element selected from Ta, Fe, Cr, Al, W, Mo, Re, Ru and Ni is contained as a constituent element. It is characterized by that.

The sputtering target of the present invention contains niobium as a metal component and silicon oxide as a resistance component, and its basic constituent element is Nb-Si-O. Since Nb and Si have similar sputter emission angles, a sputtered film with a small compositional deviation from the target can be obtained. Note that Nb is preferably present in the target in the form of a compound such as an oxide, a silicide, or a carbide.
Thereby, the composition of the obtained film can be made more uniform.

In the sputtering target of the present invention, in addition to the above basic constituent elements, carbon, Ta, Fe, Cr, A
At least 1 selected from l, W, Mo, Re, Ru and Ni
A seed element (hereinafter referred to as M element) can be contained. Carbon and the M element are effective in suppressing the resistance temperature change rate of the sputtered film (film resistor). Carbon can be present in the sputtering target as a simple substance or as silicon carbide, niobium carbide or the like. Further, the M element can be present in the sputtering target in the form of a simple substance, an alloy with Nb, or a compound thereof such as an oxide, a silicide, or a carbide thereof.

The sputtering target of the present invention includes the Nb-Si-O system, the Nb-Si-OC system, and the Nb-M system as described above.
-Si-O system, Nb-M-Si-OC system and other sintered targets have a porosity in the range of 1 to 30%. Such a relatively low density sintered body is used as the target. By doing so, the film formation rate can be improved, and since the film formation rate can be controlled by the target density (porosity), it is possible to improve the deposition energy of sputtered particles and further optimize the deposition energy. Becomes
By these, the adhesive force of the film can be increased, and further, the film having the optimum adhesive force can be obtained. Furthermore, the film composition and the sheet resistance can be made uniform.

That is, the porosity of the sintered target is 30%.
On the contrary, when the film thickness exceeds the above, the film formation rate decreases, and the frequency of occurrence of particles and the like increases, and when the brazing material is joined to the backing plate, the brazing material penetrates into the sintering target and deteriorates the film characteristics. Occurs. On the other hand, when the porosity of the sintering target is less than 1%, it is not possible to sufficiently obtain the superiority of the film forming rate as compared with the sintering target in the vicinity of the theoretical density, and the film adhesion and the film composition It is not possible to obtain effects such as homogenization. Further, if the porosity of the sintering target is less than 1%, thermal stress cracking due to the difference in thermal expansion from the backing plate is likely to occur. The more preferable porosity of the sintering target is in the range of 3 to 20%. Here, the porosity referred to in the present invention means that the polished surface of the sintered body is S at a magnification of 300 times.
Percentage of pore (hole) area observed when observing 20 or more places with EM or optical microscope. Porosity = (total area of pores) / (observed area) x 100 (%) Is.

The sputtering target of the present invention can be manufactured, for example, as follows.

First, the constituent elements of the target are determined in consideration of the intended use of the sputtering target, etc., and the starting material is selected accordingly. As the niobium starting powder, besides niobium powder, niobium alloy powder, niobium oxide powder, niobium oxide alloy powder, niobium silicide powder, niobium silicide alloy powder, niobium carbide powder, niobium carbide alloy powder, or the like can be used. As the niobium alloy, an alloy of niobium and M element or the like can be used. When carbon is included in the target, carbon powder, silicon carbide powder, or niobium carbide powder or niobium carbide alloy powder as described above is used as a starting material. Further, when the M element is contained, not only the above-mentioned alloy powder with niobium but also a simple powder of the M element, an alloy powder between the M elements, or the like can be used as a starting material.

Then, the above-mentioned respective starting powders and the silicon oxide powder are mixed so as to have a desired composition ratio to prepare a raw material mixed powder. The composition ratio of the silicon oxide powder (including the raw material that functions as a resistance component such as carbon or silicon carbide when it is used) in this raw material mixed powder is 15 to 85.
It is preferably in the range of mol%. Resistance component powder is 85mo
When it exceeds 1%, the obtained sintered body becomes brittle, the uniformity of the obtained sputtered film deteriorates, and the resistance change rate during sputtering increases, so that the resistance value of the obtained sputtered film is controlled. Becomes difficult, and variations in sheet resistance increase. On the other hand, if the content of the resistance component powder is less than 15 mol%, the specific resistance of the obtained sputtered film is lowered and the effect as a resistor is reduced. The composition ratio of carbon-containing powder such as carbon or silicon carbide is preferably in the range of 0.05 to 10 mol%. If the composition ratio of the carbon-containing powder is less than 0.05 mol%, it is not possible to sufficiently control the resistance temperature change rate,
Further, when it exceeds 10 mol%, the obtained sintered sputtering target becomes porous, the variation in the sheet resistance of the sputtered film, that is, the film resistor increases, and the etching property deteriorates. Further, it is preferable that the content of M element is 50 mol% or less.

Next, the above raw material mixed powder is formed into a sintered body having a desired shape by an atmospheric pressure sintering method, an atmosphere pressure sintering method, a hot pressing method, etc. By controlling the sintering conditions at this time, The porosity of the sintered body is in the range of 1 to 30%. For example,
When applying the hot press method, it depends on the pressing force,
It is preferable to sinter at a temperature in the range of 1300 to 1400 ° C.
If the sintering temperature is less than 1300 ° C, the porosity becomes too large, and if it exceeds 1400 ° C, the sintered density becomes too close to the theoretical density, and cracks and the like are likely to occur.
Further, the porosity can be increased by suppressing the applied pressure. Further, the porosity can also be increased by using a powder having a relatively large particle size as the starting powder, for example, a powder having an average particle size of 40 μm or more.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 First, Nb powder having an average particle size of 40 μm and an average particle size of 40 μm
And a silicon oxide powder sufficiently dried with Nb: SiO in a molar ratio.
_The ingredients were blended so as to be ₂ = 47: 53 and mixed in a ball mill replaced with an inert gas for about 30 hours. Next, this mixed powder was heated to 150 kg / cm ² in an Ar atmosphere using a hot press machine.
While applying the pressure of 1, the reaction sintering was performed at 1325 ° C. for 5 hours. The porosity of the obtained sintered body was 5%. After this,
121 × 381 × the obtained sintered body by diamond grinding
It was processed to 7 mm and further bonded to a backing plate to obtain a sputtering target.

Next, using the above sputtering target, a heating resistor for a thermal print head and a thermal print head using the same were manufactured as follows. First, as shown in FIG. 1, for example, Cr is 18 wt%
The metal substrate 1 made of an Fe alloy having a thickness of about 0.5 mm is leveled, cut to a predetermined size, deburred, and then dipped in dilute sulfuric acid kept at 50 to 70 ° C to form on the surface. The oxides that have been formed are removed, and at the same time, an activation treatment for micro-roughening the surface is performed.

Next, polyamic acid is prepared to have a predetermined viscosity by using a solvent such as N-methyl-2-pyrrolidone, coated on the metal substrate 1 to have a predetermined film thickness, and heat-treated using a baking furnace. The heat insulating layer 2 made of a polyimide resin is formed by applying a dehydration cyclization reaction while removing the solvent component to form a film.
Was formed.

Next, a SiN layer 31 and a SiC layer 32 were formed as a base layer 3 on the heat insulating layer 2 by the plasma CVD method. Next, the heating resistor layer 4 is formed on the underlayer 3 by using the above-mentioned sputtering target, and Al
Forming an electrode conductor layer made of, and patterning by etching to provide an opening to be the heat generating portion 5,
The individual electrode 6 and the common electrode 7 were formed. After that, the protective film 8 was formed so as to cover at least the heating portion 5.

In forming the heating resistor layer 4, the sputtering target of the above-described embodiment was used, and the film resistor was formed to a thickness of 100 nm by high frequency McNetron sputtering with an output of 2 kW in an inert gas atmosphere. Was formed into a film to prepare a thermal print head.

In this way, the following characteristic evaluation was performed using the thermal print head. First, the film formation rate when forming the film resistor was calculated from the film formation time and the film thickness. In addition, the presence or absence of cracks due to thermal stress of the sputtering target during formation of the film resistor was determined. Further, the variation in sheet resistance of the film resistor was measured, and the adhesive force to the substrate was evaluated.

As a result, the film formation rate was as good as 50 nm / min, the target did not crack, and the variation in the sheet resistance of the film resistor was 4.5%, which was a good value. Also, the adhesive force between the film and the substrate can be measured with a cutter on a 12 × 12 mm film sputtered on a glaze alumina substrate.
When 1 × 1 mm 144 cross-cut lines were inserted and a peeling test was conducted using an adhesive tape, the peeling area was 1% or less and the adhesive strength was excellent.

Examples 2 to 16 Using each of the mixed powders whose compositions are shown in Table 1, a sputtering target was prepared in the same manner as in Example 1. Using each of these sputtering targets, a thermal print head was produced under the same conditions as in Example 1, and the film resistor was evaluated in the same manner. The results are shown in Table 2. Incidentally, the adhesive force between the film and the substrate, the peeling area in the peeling test described above is 1% or less ○, peeling area is more than 1% 50
% Or less was marked as Δ, and peeled area exceeding 50% was marked as x.

In Comparative Examples 1 and 2 in the table, sputtering targets having a porosity outside the range according to the present invention were used, and the same evaluation results are shown.

[0027]

[Table 1]

[Table 2] As is clear from Table 1, the sputtering targets according to the respective examples are excellent in film forming rate, and the obtained film resistors (heating resistors) have little variation in sheet resistance and are excellent in adhesive force. It greatly contributes to the improvement of the characteristics of the thermal print head.

[0028]

As described above, according to the sputtering target of the present invention, the film formation rate can be improved, and the composition and sheet resistance are excellent in uniformity, and the adhesion ratio is high. It is possible to form the resistance film with good reproducibility. Therefore, it is possible to stably provide a film resistor that is useful as a heating resistor of a thermal printer head.

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view showing the configuration of a thermal printer head manufactured in an embodiment of the present invention.

[Explanation of symbols]

 1 ... Metal substrate 2 ... Insulating layer made of polyimide resin 3 ... Underlayer 4 ... Heating resistor layer 5 ... Heating part 6 ... Individual electrode 7 ... Common electrode 8 ... Protective film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumiyuki Kawashima 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa, Ltd.

Claims (3)

[Claims] 1. A sputtering target containing niobium, silicon and oxygen as at least constituent elements and having a porosity in the range of 1 to 30%. 2. The sputtering target according to claim 1, wherein the sintering target further contains carbon as a constituent element. 3. The sputtering target according to claim 1, wherein the sintering target further contains Ta, Fe,
A sputtering target containing at least one element selected from Cr, Al, W, Mo, Re, Ru and Ni.