JPH0637096A - Annealing method for thin film - Google Patents

Abstract

PURPOSE:To provide a method for improving characteristics by applying a pulselike electric energy to a circuit formed of a thin film material. CONSTITUTION:A pulselike electric energy is applied between terminals of an electronic component by an aging unit composed of a DC power source 1 and an oscillator 12 for generating a signal for controlling a voltage applying time, and the film is heat treated by utilizing a small Joule heat generated by the film itself. Since the heat generation of the film itself is used, its purpose is performed by the small energy, and hence a large-scale facility is not required, and an effect is obtained in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film annealing method for improving the characteristics of a thin film circuit.

[0002]

2. Description of the Related Art There are many electronic parts such as semiconductors and sensors that are processed into various types of thin films to exhibit desired functions, and vapor phase epitaxy is generally used for forming thin films. .

In the thin film formed by the vapor phase growth method, micro defects generated by various factors are aggregated in the film, and its function is often not sufficiently exhibited due to disturbance such as stress generation. In such a case, after the thin film is formed, or after the subsequent processing step, stress relaxation and defect recovery processing are usually performed by heat treatment called annealing.

For the conventional annealing treatment, large-scale equipment such as an atmosphere furnace or a vacuum furnace is generally used. When operating these furnaces, a large-scale furnace itself needs to be heated and cooled, so that the time required for one process is long and the operating cost is high. In particular, gas replacement to keep the atmosphere constant and vacuum exhaust to prevent reaction of the film required large-scale auxiliary equipment such as gas introduction equipment and exhaust equipment.

An example thereof is shown in FIG. FIG. 5 is a schematic diagram of a magnetic film annealing apparatus called an annealing method in a rotating magnetic field.

In the figure, 1 is a substrate, 2 is a diffusion pump,
3 is a rotary pump, 4 is a heater, 5 is a magnet, and 6 is a motor.

To prevent the magnetic film from deteriorating, 10 ^-6 (Tor
After evacuating to a high vacuum of r) order, the substrate on which the magnetic thin film is formed is heated by a heater to about 400 ° C., the heating is stopped for a certain period of time to keep the temperature of the entire substrate uniform, and the substrate is naturally cooled to room temperature. . During evacuation and heating during this process, a magnet provided outside the vacuum vessel is fixed and a DC magnetic field is applied,
During cooling, the magnet is rotated by a motor to cool in a rotating magnetic field. As can be seen from this example, in addition to the need for exhaust equipment and a rotating magnetic field application device, it took about 2 hours to perform one process for heating and cooling in vacuum.

[0008]

SUMMARY OF THE INVENTION As described above, the present invention is to simplify the equipment and time required for annealing for enhancing the function of a thin film.

[0009]

In order to solve the above-mentioned problems, the present invention applies pulsed electric energy to a thin film and uses the heat generated by the thin film itself to perform annealing.

[0010]

When pulsed electric energy is applied to the thin film forming a part of the component, the thin film portion has a small cross-sectional area, so that even a small amount of energy causes heat generation and the thin film itself reaches a temperature sufficient for annealing. However, this amount of heat is so small that it is immediately dissipated to the substrate and protective film, so that the temperature of the entire component hardly rises, but the thin film itself is the heat source and the most efficient Since heat can be used, an annealing effect can be obtained even with a slight heat generation. In this case, the effect is enhanced especially when the heat is generated in a concentrated manner within a short time. Therefore, how to concentrate and apply the electric energy in a short time becomes a problem.

[0011]

EXAMPLES Among the electronic parts having the above-mentioned problems, one of the most remarkable effects of the present invention is as follows.
The present invention will be specifically described using a magnetic sensor (hereinafter referred to as an MR sensor) that utilizes the magnetoresistive effect of a ferromagnetic thin film.

A Ni-Fe (20 wt%) material was formed into a thin film of 0.1 μm on a substrate 18 by a vacuum evaporation method, and after forming a magnetic sensitive portion 16 having a line width of 15 μm by a photolithography technique,
A protective film is formed and cut into elements to separate the terminals 17a, 17
By connecting b and 17c, the MR sensor shown in FIG. 3 was manufactured. Between the terminals (between 17a-17b, 17b-17c
Pulse) was applied by the aging circuit shown in FIG.

FIG. 1 is a conceptual diagram of an aging device composed of a capacitor 15, a relay 14 for switching both ends of the capacitor 15 to a DC power supply 11 and an MR sensor 13, and an oscillator 12 for generating a signal for controlling the relay 14. so,
A pulse having a waveform as shown in FIG. 2 is applied between the terminals of the MR sensor 13 by a control signal from the oscillator.

The application conditions are: (1) voltage: 600 (V), energy: 0.4 (m)
J) (2) Voltage: 600 (V), Energy: 1.3 (m
J) (3) Voltage: 600 (V), Energy: 1.8 (m
J) (4) Voltage: 600 (V), Energy: 3.6 (m
J) (5) Voltage: 600 (V), Energy: 5.4 (m
J).

The rate of change in resistance (Δρ / ρ) was measured before and after applying the pulse under each condition, and the degree of improvement in characteristics was evaluated by the rate of change.

The characteristics of the embodiment are shown in FIG. The rate of change in resistance increases with the applied energy density, indicating the annealing effect of the method according to the present invention. (5) in the examples
On the contrary, the change rate is decreased under the condition of 1. However, this phenomenon occurs even in the conventional method shown in FIG. 5 when the heating temperature is too high. From this tendency, the present invention has the same mechanism as the conventional method. It is considered that the annealing effect is exhibited in.

[0017]

As described in the above embodiments, according to the present invention, pulsed electric energy is applied to a thin film circuit which constitutes an electronic component to generate heat instantaneously, so that only a thin film can be formed with a small amount of energy. Can be heated. Therefore, not only the processing time can be shortened as compared with the conventional method, but also a large-scale equipment is not required and an industrially excellent annealing method is provided.

Although the effect of the present invention has been described in detail in the present invention by using the MR sensor, the effect of the present invention is not limited to the MR sensor, but an electronic component formed by a fine thin film circuit such as a thin film resistor or semiconductor. Also in the above, similar effects can be obtained with respect to the characteristics improved by the secondary annealing treatment.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a pulse applying device for carrying out the present invention.

FIG. 2 is an applied pulse waveform diagram used in the present invention.

FIG. 3 is a schematic diagram of an MR sensor.

FIG. 4 is a characteristic diagram showing the effect of the present invention.

FIG. 5 is a schematic view showing an annealing device in a rotating magnetic field by a conventional method.

[Explanation of symbols]

 11 DC power supply 12 Oscillator 13 MR sensor 14 Relay 15 Capacitor 16 Magnetically sensitive part 17a, 17b, 17c Terminal 18 Board

Claims (2)

[Claims] 1. A method of annealing a thin film, characterized in that pulsed electric energy is applied to both ends of a thin film circuit having a desired shape formed on a substrate. 2. The thin film annealing method according to claim 1, wherein the thin film is a magnetic material.