JPS5817828B2 - Adhesive layer formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an adhesion layer that ensures adhesion between a single crystal substrate such as quartz or sapphire and a metal film.

A particularly preferred field of application of the present invention is the manufacture of thin film magnetic heads, but it can also be applied to other fields, such as wiring processes for ICs and other wiring processes.

To explain thin film magnetic heads, despite their small size, the recording current is relatively large, so the conductor part of the head generates heat, and in order to dissipate this heat, a thin film magnetic head with good thermal conductivity is used. A crystal substrate, such as quartz or sapphire, is used.

However, when a magnetic film (permalloy film) is formed on this single crystal substrate and polished to form a read/write (R/W) gap, the magnetic film peels off from the substrate.

Therefore, attempts have been made to provide a thin adhesion layer of titanium, chromium, molybdenum, or the like between the magnetic film and the substrate in order to increase the adhesion between the magnetic film and the substrate and prevent peeling.

However, even with this attempt, a satisfactory anti-peeling effect could not be obtained.

Therefore, an object of the present invention is to eliminate the above-mentioned peeling of a magnetic film from a single crystal substrate, and also to prevent peeling during manufacturing of a metal film according to the purpose on a predetermined single crystal substrate. It is to form.

Further, another object of the present invention is to provide a single crystal substrate and a metal F: Kyo =
': : = Adhesive layer with adhesion between soil and CD The above purpose is to form an adhesion layer between a single crystal substrate and a metal film by adding aluminum or an aluminum-based alloy onto the substrate. This is achieved by an adhesion layer forming method characterized in that a titanium thin film is formed on this thin film, and the above-mentioned metal film is formed thereon using these thin films as an adhesion layer.

The aforementioned substrate may be a single crystal substrate of quartz, sapphire, or silicon, and a quartz substrate is preferable for the substrate of the thin film magnetic head.

It is preferable to form a thin film of aluminum or an aluminum-based alloy on a predetermined single crystal substrate with a thickness of 0.1 μm or less by sputtering.

It is also possible to use means other than sputtering, such as evaporation or ion blasting.

A, /, -4%C for alloys whose main component is aluminum
There are u alloys, A, and 4-Si alloys, which are hereinafter included in the term aluminum.

The reason why the thickness of the thin aluminum film is set to be 0.1 μm or less is because recrystallization of aluminum that is thicker than this causes unevenness on the surface.

The recrystallization of aluminum here refers to the coarsening of At crystals due to recrystallization-grain growth generated by heat during sputtering, and the higher the temperature and the thicker the film, the more it is accelerated and the roughness of the film surface becomes more severe.

The reason why aluminum can be used for the adhesive layer in the present invention is considered to be as follows.

Generally, the adhesion of a formed film to 8102 (a component of quartz) can be estimated based on the magnitude of the oxide formation energy of the film.

This is because the more negative the oxide formation energy, the more stable the oxide is.

Figure 1 shows the relationship between standard free energy and temperature in the formation of oxides of aluminum, titanium, silicon, and chromium. At the interface (at 0°C), 4/3At+02-2/3A1
203 ΔG"-252kcalSt 02
−= S r +0 ΔGCL: +19
5kca14/3M well S Ic);, =2/3Az2
A reaction of o3+ 81Δbi' -57 kcal can be expected.

That is, the adhesion is increased by reacting oxygen and aluminum of the SiO□ substrate to form an oxide.

On the other hand, similarly in the case of titanium and chromium, 2/3Cr2 o3+ St =S t 02 +4.
/3Cr ΔGL-28kcalTi+SiO□=Ti
A reaction of O□+Si ΔG=-6kcal can occur at each interface.

Therefore, the adhesion strength between the SiO□ substrate and each adhesion layer of aluminum, titanium, and chromium is greater than that of aluminum>titanium>
This is because it can be estimated that aluminum has the highest value of 1 in the order of chromium.

The same would apply to sapphire (A403) substrates.

Furthermore, it is preferable to form a titanium thin film on the aluminum thin film described above to form a two-layer adhesive layer.

The reason for this two-layer structure is that, especially when the magnetic film in a magnetic head is formed on an aluminum thin film adhesion layer, aluminum recrystallizes due to temperature and the surface becomes uneven when the film is thick. In order to prevent the deterioration of the magnetic properties, a titanium thin film is formed on the aluminum thin film as a diffusion prevention film for At at high temperatures. be.

The titanium thin film here is preferably formed by sputtering, but it is also possible to form it by vapor deposition or ion blasting.

The material of the metal film is permanent or roy if it is a magnetic layer of a thin film magnetic head, or tungsten or molybdenum if it is used in a wiring process such as ■C.
Alternatively, copper or the like can be used as long as it is used in the fine wiring process.

These metal films are formed by sputtering, vapor deposition, or ion blasting.

As mentioned above, the advantage of the aluminum thin film adhesion layer is that it is relatively low temperature (around 200°C for sputtering and 30°C for vapor deposition).
It is possible to form a film at a temperature of around 00°C) and ensure strong adhesion.

The present invention will be explained below with reference to experimental examples and examples.

Experimental Example A 500mm thick aluminum thin film was formed on a quartz substrate at 200°C by sputtering, and a 6μm thick Vermilo (N i Fe ) film was then formed on this aluminum thin film at 200°C by sputtering. Formed.

A polishing test was conducted using the sample thus prepared, and it was confirmed that the permalloy film did not peel off.

EXAMPLE A thin aluminum film with a thickness of 500 mm was formed on a quartz substrate at 200°C by sputtering, and a thin film of 500 mm thick was formed on this thin aluminum blade by sputtering in the same manner.
A titanium thin film having a thickness of 0.05 mm was formed at 20'0° C. to form an adhesion layer having a two-layer structure.

Then, a permalloy (NiFe) film having a thickness of 6 μm was formed at 200° C. by sputtering on this titanium thin film.

A polishing test was conducted using the sample thus prepared, and it was confirmed that the permalloy film did not peel off.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the relationship between oxide formation energy and temperature of aluminum, titanium, silicon, and chromium.

Claims (1)

[Scope of Claims] 1. A method for forming an adhesive layer between a single crystal substrate and a metal film, in which a thin film of aluminum or an alloy containing aluminum as a main component is formed on the single crystal substrate, and 1. A method for forming an adhesive layer, which comprises forming a titanium thin film on a substrate, forming an adhesive layer on the thin film, and forming the metal film on the adhesive layer. 2. The adhesive layer forming method according to claim 1, wherein the single crystal substrate is a single crystal of quartz, sapphire, or silicon. 3. The adhesive layer forming method according to claim 1, wherein the material of the metal film is permalloy, tungsten, molybdenum, copper, or gold. 4. The adhesive layer forming method according to claim 1, wherein the thin film of aluminum or an alloy mainly composed of aluminum and the thin film of titanium are formed by sputtering, vapor deposition, or ion blasting. 5. The adhesive layer forming method according to claim 4, wherein the thin film of aluminum or an alloy containing aluminum as a main component has a thickness of 0.1 μm or less.