JPS5824040B2 - Method for forming insulating layer of crossover wiring part in thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for forming an insulating layer in a crossover wiring section in a thermal head.

Conventionally, in the multilayer wiring section of thin film devices such as line-tod type thermal heads that have high-temperature heating elements on the same substrate, a lower layer conductor is first formed on an insulating substrate by film technology such as vapor deposition or sputtering, and then the entire multilayer wiring area is formed. A polyimide film that covers the insulating layer is baked at 200 to 300°C for about 2 hours, and a photoresist is applied on top of it to expose the part where the lower layer conductor and the upper layer conductor are connected. After partially dissolving the polyimide film and removing the photoresist, the upper layer conductor is formed.

Such conventional methods have problems such as the long time it takes to bake the polyimide film, and the fact that pinholes are frequently generated in the polyimide film when it is etched, causing short circuits between conductors. was there.

An object of the present invention is to eliminate the above-mentioned problems, and the purpose is to form an insulating layer with a 5102 film in a method for forming an insulating layer in a crossover wiring section in a thermal head having high-temperature heating elements on the same substrate. Then, a mask for partial elution of the 8102 film for interconnection between conductors in the multilayer wiring region of the crossover wiring section was formed into a two-layer film structure of the NiCrAu film and the photoresist film formed on the S + 02 film. The present invention can be achieved by providing a method for forming an insulating layer of a crossover wiring portion in a thermal head characterized by the following.

The present invention will be explained below with reference to the drawings.

FIG. 1 is an explanatory diagram of the manufacturing process of the multilayer wiring of the crossover wiring section in the thermal head according to the present invention, and FIG. , In figure b, an insulating layer of SiO2 film 3 is formed by sputtering to a thickness of about 1 to 2 μm covering the entire multilayer wiring area of substrate 1, and in figure 0, Ni is formed on the SiO2 film 3.
A Cr-Au film is deposited, and the above N i Cr-Au film is deposited in figure d.
A photoresist film 6 with conductor connection parts 5 exposed is applied on the film 4, and the N exposed from the photoresist film 6 is shown in figure e.
The iCr-Au film 4 is dissolved away with an etching solution, and then f
In the figure, the S r 02 film 3 exposed from the two-layer mask consisting of the photoresist film 6 and the NiCr-Au film 4 was heated with HF.
After removing the photoresist film 6 as shown in figure g, the upper layer conductor 7 is formed as shown in the figure below. The conductor 7 is joined.

The differences between these processes and the conventional process are as follows: (1) Elimination of polyimide film formation, firing, and partial etching steps (2) Addition of SiO□ film sputtering and partial etching steps (3) NiCr-Au Film vapor deposition and partial etching steps are added, and for multilayer wiring sections, the number of manufacturing steps is reduced because firing of the polyimide film is no longer required, but the number of manufacturing steps is increased.

However, 8102 as an anti-oxidation layer and a NiCr-Au film as a conductor base are widely used in element parts other than multilayer wiring parts of thin film devices, such as thermal resistance elements, which have relatively high heat generation elements. If you use the same process as those,
The number of processes for thin film devices is often reduced rather than increased.

The two-layer mask consisting of the NiCr--Au film 4 and the photoresist film 6 is sufficiently protected even when the relatively thick SiO□ film is removed by the HF-based etching solution.

Next, as an embodiment of the present invention, a case where the present invention is applied to a line tod type thermal head will be described.

FIG. 2 is an explanatory diagram of the circuit of a line-tod type thermal head used in facsimile machines, etc., and a resistor 9 that instantaneously heats up to 200 to 400°C is connected in series with a diode 8. The diodes 8 are arranged in parallel at a density of ~10, forming a diode array of several diode arrays, one end of which is connected to the group terminal 10, and one end of the resistor 9 is connected to the select terminal by cross-over wiring other than the conductor connection point 12. 11.

In such a thermal head, a film is formed on an alumina substrate, but when the present invention is applied to the crossover wiring part, the formation of the film 3 at 8102 in FIG.
It can be formed simultaneously with the i02 insulating film, and the NiCr-A shown in FIG.
The u film can also be simultaneously deposited when forming conductors other than the crossover wiring portion.

As a result, the manufacturing process and manufacturing man-hours are reduced, and short-circuit failures between conductors are greatly reduced, and the effects are extremely significant.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a method for manufacturing multilayer wiring according to the present invention, and FIG. 2 is an explanatory diagram of a circuit of a line-top type thermal head to which the present invention is applied. 1... Insulating substrate, 2, 2'... Lower layer conductor, 3... 5i02 film, 4... Ni
Cr-Au film, 6... Photoresist film, 7
...... Upper layer conductor.

Claims (1)

[Claims] 1. In a method for forming an insulating layer in a crossover wiring section in a thermal head having high-temperature heating elements on the same substrate, an insulating layer is formed with a 5IO2 film, and the above-mentioned method for connecting conductors in a multilayer wiring area of the crossover wiring section is provided. SiO
A method for forming an insulating layer in a crossover wiring section in a thermal head, characterized in that a mask for partial elution of the □ film has a two-layer structure of a NiCr-Au film formed on the SiO □ film and a photoresist film.