JPH02112957A - Thermal head and manufacture thereof - Google Patents

Abstract

PURPOSE:To form a fine pattern and to obtain a thin film type thermal head by regulating a resistance value with a ruthenium oxide thin film made of specific element, Ru and O, and plasma etching it in an atmosphere containing at least O with a wiring conductor film made of Au or Al as a mask to develop a fine pattern. CONSTITUTION:A resistance value is regulated with a ruthenium oxide thin film made of one or more types of elements selected from Mn, Co, Cr, In and Mo, Ru and O, and it is plasma etched in an atmosphere containing at least O with a wiring conductor film made of Au or Al as a mask. Oxide having high valence number is formed as a volatile product by the oxygen plasma having high energy, and reactive ion etched with oxygen gas. Since the oxygen gas is employed, detrimental decomposition product is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal head used in a print head of a facsimile or printer, and a method of manufacturing the same.

BACKGROUND OF THE INVENTION Ruthenium oxide resistors are widely used in various electronic devices, such as hybrid electronics, thermal heads, chip resistors, resistor network components, and sensors. These ruthenium oxide resistors are thick film resistors made by mixing inorganic powder containing RuO2 as a main component with glass frit, resin, and solvent, making a paste, and printing and firing the paste. Since these cannot be produced by printing, it is naturally possible to form a pattern, but the pattern width is 1
The limit is approximately 00 μm, and it is impossible to produce a pattern with high accuracy. In addition, these are dispersed thick films using an inorganic binder, and compared to thin films, the resistance characteristics vary widely and the heat dissipation and power durability are inferior.

There are two types of thermal heads: a thin-film type using a thin-film resistor and an original model using a thick-film resistor.Thick-film thermal heads using a ruthenium oxide resistor have lower resolution, They are inferior to thin-film types in terms of performance such as image quality, high speed, and power consumption.

Since thin film resistors are generally manufactured using a vacuum device, it is necessary to form a pattern using a photoreno process and to be able to etch the thin film resistor in order to manufacture a thin film type thermal head.

As with thick films, there are methods to obtain thin films by printing and baking, but the accuracy and reproducibility of patterns can only be obtained on the same level as with thick films. Etching can be broadly divided into wet etching and dry etching. Wet etching is a method of etching using a chemical solution in a liquid bath. Dry etching is a method of etching using neutral gas, gas phase ions, radicals, etc., and a method of etching by turning the gas into plasma is called plasma etching. Thin film resistors have superior properties as resistors compared to thick films, but RuO2 is insoluble in acids and there is no suitable etchant, so ruthenium oxide thin film resistors cannot be wet etched. . As a reported example of dry etching for a ruthenium oxide thin film, plasma etching using oxygen gas (O2) has been found to be effective.

Problems to be Solved by the Invention However, the RuO2 thin film has a resistivity of about 500 μΩ·α, and in order to be used in a thermal head, it is necessary to add additives to increase the resistance value. Si.

When resistivity is increased by adding mulch, (a, Ba, etc.), the etching rate decreases when the composition ratio of 1 to Ru exceeds 10 at%. Therefore, it is an object of the present invention to provide a ruthenium oxide thin film resistor that can control the resistance value over a wide range and a patterning method for the same, and to provide a ruthenium oxide thin film resistor with excellent characteristics. The aim is to create a thin-film thermal head using thin films.

Means to solve problems In order to solve the above problems, the present invention provides Mn.

The resistance value is adjusted by making a ruthenium oxide thin film made of one or more elements selected from Co, Cr, In, Mo, Ru and 0, and it is used for wiring made of MU or MU. A thermal head is produced by plasma etching a fine pattern using a conductor pattern as a mask in an atmosphere containing at least O.
It is.

Effect: By using the above composition and etching method, the resistance value of the ruthenium oxide thin film can be controlled over a wide range, a fine pattern can be formed, and a thin film type thermal head can be manufactured.

Example Examples of the present invention will be described below.

That is, the present invention adjusts the resistance value by forming a ruthenium oxide thin film consisting of one or more elements selected from In, Go, Cr, In, and Mo, Ru, and 0, and then The method is characterized in that plasma etching is carried out in an atmosphere containing at least 0 using a wiring conductor film made of E as a mask.

Table 1 below shows the relationship between the sheet resistance and the composition ratio when one of Mn, Co, and Or is added to Ru to form a binary oxide. 100Ω/mouth ~ 300m1/mouth (film thickness is 5
00 persons) sheet resistance values have been obtained. The sheet resistance value required for the thin film resistor used in a thin film type thermal head varies depending on the use of the thermal head, but is 100 Q/mouth to 3. It can be seen that the required resistance value can be obtained by using the above-mentioned additives.

(Leaving space below) Table 1 oo: 300MΩ/or more Various apparatuses are used for plasma etching, but in this example, as shown in FIG. 12 (cathode) and 14 (anode)), and a reactive ion etching apparatus (high frequency power frequency 13, seMHz) having a configuration in which an object to be etched 13 is placed on the cathode 12 is used. In addition,
15 is a sample stage, 16 is an insulator, 1A is a high frequency power supply, 18
1 is a gas supply system, and 19 is an exhaust system. Additionally, reactive ion etching has the following characteristics.

(2) Etching occurs due to physical effects as ions are accelerated by the ion sheath on the cathode.

■ There is less undercutting because the ions have directionality.

(2) Since a reactive gas is used, the selectivity for masks and substrates is higher than in sputter etching using an inert gas.

The etching mechanism of dry etching is basically divided into three types: physical reaction, chemical reaction, and physicochemical complex reaction. In the case of reactive ion etching, etching progresses through a physicochemical complex reaction. In this example, Mn, Co
This method is based on the discovery that a ruthenium oxide thin film consisting of one or more elements selected from Cr, In, and Mo, Ru, and 0 can be reactively etched by oxygen gas (02). . Comparison of etching rates for binary oxide thin films of oxygen gas and argon, Ru-Mn-0°Ru-co-0, and Ru-0r-0 (composition ratio of additives to Ru is 50 at%) under the following conditions: The results are shown in Figures 2 (!L) to (C). Flow rate: 10SOCII.

Pressure crab 0.1 torr, high frequency chamber crab 100
W, electrode temperature: 20'C, electrode spacing = 70ff. As shown in FIG. 2, the etching rate using oxygen gas is higher than that using argon gas. The species generated in oxygen plasma are o2, o5. o, o", o2+, o"(#
indicates activation). Of these, 02+ and 0+ contribute to the S-sickling effect, and their ionization cross section and sputtering rate are both smaller than that of argon. Therefore, the reason why the etching rate of oxygen gas is higher than that of argon is thought to be due to the chemical reaction between the above-mentioned composite oxide and oxygen radicals or ions, producing volatile products, and it is not etching due to a mere sputtering effect, but reactive etching. This shows that ion etching is occurring. It is known that RuO, RuO2, Ruρ5, and RuO4 exist in ruthenium oxide, but among these, RuO4 has a boiling point of 40. It is the substance that has the lowest O'C and is easily vaporized. However, since this is a reaction in a high-energy plasma, other volatile products related to Ru include Ru02 (
x≧3). Mn.

Regarding Co and Or, since these are transition metals, there are several oxides with different valences, and among these, oxides with higher valences are formed as volatile products by high-energy oxygen plasma. Conceivable. FIG. 3 shows the change in etching rate depending on the composition. Etching conditions were oxygen gas flow rate: 2°sccm, pressure crab 0.1 torr.
r, high frequency crab 100W, electric temperature: 20°
There is little increase or decrease in etching rate due to changes in Co composition,
Etching is possible regardless of the composition ratio. In semiconductor processes, fluorine-based gases such as CF4, C;
Plasma etching using chlorine-based gases such as etching is widely used.

When these gases are decomposed, they produce toxic fluorine and chlorine radicals, so expensive exhaust gas treatment equipment is required. However, since the etching method of the present invention uses oxygen gas, it has the advantage that no harmful decomposition products are produced.

Although Mn, Go, and Or are used as additives in the above examples, similar effects can be obtained by using other volatile oxide-forming metal elements, such as Mo and In. be able to.

Specific examples will be described below.

(Example 1) As shown in FIG. 4a, a so-called glazed alumina substrate 53 in which a glass glaze layer 62 is formed on an alumina substrate 61 is coated with Ru − 500 by RF sputtering using a RuO2/MnO2 sintered body as a target. M n
-0 thin film heating resistor 64 (composition ratio Ru75Mn250)
(ILt%), and after sequentially laminating a wiring conductor film 56 made of Au on this, the wiring conductor film 66 is patterned by a photolithography process to obtain a wiring pattern 56 as shown in FIG. Ta. The net resistance value of the thin film heating resistor 66 is 1. It was OokΩ/mouth. Using this wiring pattern 66 as a mask, the oxygen gas flow rate is 20 BOOm,
Etching was performed using the reactive ion etching apparatus under the conditions of a pressure of 0.1 torr, a high frequency power of 160 W, and an etching time of 1 S to obtain a thin film heat generating resistor pattern 57 as shown in FIG. 4C.

When the etching amount of the glass glaze layer 62 and the wiring conductor film 55 was examined under the same etching conditions, both were found to be 3o.
It was less than 8 and could be ignored.

This is a conductor for wiring and wires; the same result was obtained even if the pattern 65 was mulled. In the present invention, etching is performed using oxygen plasma, so it is preferable that the etching mask be resistant to etching by oxygen plasma and oxidizable. In the present invention, Au and silica, which are used as conductor films for wiring, can be used as masks as long as they meet these conditions, so they have the advantage of high process efficiency. That is, it can be said that by using the ruthenium oxide thin film heating resistor and etching method according to the present invention, the heating resistor 65 can be etched with a high selectivity. Further, the undercut was 0.5 μm or less, which was negligible. Next, unnecessary portions of the wiring pattern 66 were removed by a photolithography process, and a wear-resistant film was formed using S-G. Its configuration is shown in FIG. 61 is an alumina substrate, 62 is a glass glaze layer, 63a and 63b are conductive films for wiring, 64 is a thin film heating resistor, and 65 is an abrasion-resistant protective film. Note that for convenience of explanation, the wear-resistant protective film 65 is not partially formed in the drawing.

The thin film heating resistors 64 were arranged at a density of 8 pieces/H, and the resistance value variation was within ±1 inch.

When a thin film thermal head having a similar structure is fabricated by wet etching using T i C/S 102 as the conventional thin film heating resistor 64, the resistance value variation is within ±10%. A thermal head made using a ruthenium-based thin film heating resistor and an etching method is far superior.

In addition, both pulse width 1m5eC, pulse period 10m'&
We compared the durability by applying continuous pulses.

Comparing the power per unit area (breakdown power, unit W/-) of the thin film heating resistor that gives a resistance value variation of 10% when 6" pulses are applied 104 times, the thermal head according to the example of the present invention has a power of 70 W/-. -, which was a big improvement from the conventional type's 40W/-.Also, the Ru-Go
-Cr-0 thin film, Ru-In-0 thin film, Ru-Mo-0
Thin film (・/- resistance value is 1.05 kv, 1.
When using 26kfL/11.1Okv as the heating resistor, the resistance value variation is within 1%, and the breaking power is 70W/, J, 64W/x, n, and e7w/, respectively.
Almost the same performance as - was obtained. This is considered to be because the thermal head according to the present invention uses an oxide resistor and therefore has excellent environmental stability such as oxidation resistance. By using the ruthenium oxide resistor and the etching method of the present invention, it was possible to fabricate a thermal head having a ruthenium oxide thin film resistor with high and low resistance values, which was previously impossible to fabricate.

In this embodiment, the thin film heating resistor is formed by RF sputtering method 1-, but it goes without saying that the present invention is effective even when it is manufactured by reactive vapor deposition or thermal decomposition of an organic metal.

Effects of the Invention According to the present invention, it is possible to provide a thermal head using a ruthenium oxide thin film heating resistor having a high resistance value, which was previously impossible to manufacture.

[Brief explanation of the drawing]

Figure 1: Schematic diagram of beam active ion etching device.
Figure 2 is a diagram comparing the relationship between etching time and etching amount for acid deposition and argon, Figure 3 is a diagram showing changes in etching rate depending on composition ratio, and Figure 4 is a pattern of a thin film heating resistor of a thermal head. FIG. 5 is a schematic diagram showing the coating process, and FIG. 5 is a diagram showing the configuration of a thin film type thermal head. 51... Alumina substrate, 62... Glass glaze layer, 53... Glazed alumina substrate, 54 Ru-M n-0 thin film heating resistor, 56...
... Conductor film for wiring, 66... Patterned conductor for wiring, 67... Patterned Ru-Mn-0 thin film heating resistor. Name of agent: Patent attorney Shigetaka Awano and 1 other person +t
-Ji history 12.14...Electrode +3-・Fuetsu+Nu 15...-Final scale 16-・Zetsuw & Yon-・ Ink mat Recitation 18-・Gas compensation thread Figure 3 ( s/m1n) IC0 (αtI/1) /? (jlko 7'TT ru shi secret 70 original, original
Paper β (roni 1-1-di- alumina substrate glass urea support layer urea support door alumina cover temporary shoulder M-P low m body r-book koshii soru yorisu 1 with turn 11-1・p・&mo・・− 63b・- 1...- Otsu 5゛Alumina substrate version Karasurashi-i1 ＆! 熟F＠设杀 (No. 11) Arrangement @滓jun (1!ll'l phone number) Book IgI contract I+!Low Foil wear resistance story 1 Figure ≠

Claims (2)

[Claims] (1) A ruthenium oxide thin film formed on a substrate having at least an electrically insulating surface and consisting of one or more elements selected from Mn, Co, Cr, In, and Mo, Ru, and O. A thermal device comprising a heating resistor, a wiring conductor film made of Au or Al for energizing the thin film heating resistor, and a wear-resistant protective film for protecting the thin film heating resistor and the wiring conductor film. head. (2) A ruthenium oxide thin film heating resistor made of one or more elements selected from Mn, Co, Cr, In, and Mo and Ru and O is placed on a substrate whose surface at least has electrical insulation properties. After forming an Au or Al thin film thereon, it is etched into a predetermined shape by a photolithography process to form a wiring conductor film, and using this wiring conductor film as a mask, plasma etching is performed in an atmosphere containing at least O, A method of manufacturing a thermal head, comprising forming a pattern of the thin film heating resistor.