JP2001223176A - Laser irradiation device and laser irradiation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem concerning very inferior reproducibility of radiation energy which is caused by instability, change of condition with time, nonlinearity of an optical element, etc., in a laser irradiation device. SOLUTION: A laser irradiation device is provided with at least a device oscillating a laser having a specified wavelength, a device changing the output of a laser light, an optical device controlling a laser light to be in a desired shape, and a device having a structure which introduces a laser light on a surface of a substrate while the substrate is held in a vacuum or an atmosphere substituted by specified gas. In the laser irradiation device, a means measuring laser energy in the vicinity of the surface of the substrate, a means analyzing the measured laser energy and a means which adjusts the output of a laser light on the basis of the analized laser energy are installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser irradiating apparatus and a laser irradiating method, and more particularly to crystallization and activation of a semiconductor thin film, formation of a thin film and fine processing using a strong light such as an excimer laser. The present invention provides a laser irradiation device and a laser irradiation method that can be performed, stabilizing the performance and improving the yield of thin film transistors formed on a glass substrate such as a liquid crystal display device, fine processing of a transparent conductive thin film, II-VI system It significantly contributes to the stabilization of performance of a light emitting device or the like using a compound semiconductor thin film.

[0002]

2. Description of the Related Art In recent years, a thin film transistor (TFT) liquid crystal display, which is widely used as a monitor of a personal computer or a display of a car navigation system, uses glass as a substrate, so that a TFT array is formed at 600 ° C. or higher. High temperature manufacturing process cannot be used. Therefore, a method such as a plasma CVD method or a normal pressure CVD method capable of forming a thin film at a low temperature is used for forming a semiconductor thin film or an insulating film.

In recent years, TFTs using polycrystalline silicon as a semiconductor thin film in place of conventional amorphous silicon have been developed for improving the performance of the TFT. As one method of forming polycrystalline silicon, an amorphous silicon film or a microcrystalline silicon film is crystallized by irradiating a laser beam absorbed by a semiconductor thin film, or is implanted into a part of the formed polycrystalline silicon film. Technologies using laser light have been developed, such as activating impurities and removing and modifying defects in a polycrystalline silicon film.

Further, a part of a transparent conductive thin film formed on a glass substrate is irradiated with laser light to remove the transparent conductive thin film, and is used as a counter electrode of a liquid crystal display device. Processing technology has also been developed. Furthermore, in the production of a light-emitting element using a II-VI compound such as ZnS or ZnSe, a ZnS or ZnSe pellet serving as a base material is evaporated in a vacuum by irradiating a laser beam with laser light, and is placed at an opposite position. Technology for depositing thin films on substrates has also been developed.

[0005] The above-mentioned technologies are all technologies that utilize heating, melting, or evaporation of a target material by irradiating a laser beam, such as an excimer laser beam, which is absorbed by the target material. Yes, select the wavelength to be used according to the target substance. The laser irradiation equipment used for such technology generally includes a laser oscillator that oscillates a laser of a specific wavelength, an output controller that controls the output of the laser light, an optical system that controls the transmittance of the laser light, and a laser light. An optical system for controlling a desired shape, an apparatus having a structure for introducing a laser beam to the surface of the substrate while maintaining the substrate in a vacuum or an atmosphere replaced with a specific gas, and the like.

[0006]

The conventional laser irradiation apparatus controls the energy of the laser light to be irradiated by keeping the output of the laser oscillator or the transmittance of the laser light in the optical system constant. However, in practice, the energy of the laser beam applied to the object is: (1) a change in transmittance due to a temperature change, a change over time, deterioration, etc. of an optical element used in an optical system for controlling the transmittance of the laser; Deviation in transmittance due to non-linearity of the optical element used in the optical system that controls the transmittance of the laser. (3) Due to factors such as cloudiness of optical components such as reflective mirrors and laser light introduction windows, and changes in transmittance due to dirt. Not always stable. Therefore, if the irradiation energy is changed frequently, if the device is used continuously for a long time, if the intervals between use are irregular, or if the temperature or humidity of the environment in which the device is used changes greatly, the irradiation Energy reproducibility becomes very poor. As a result, for example, in the case of a polycrystalline silicon TFT used for a liquid crystal display device, the variation in characteristics between substrates or lots becomes large, and in some cases, the yield is reduced. In the case of fine processing of a transparent conductive thin film, etc., variations in processing dimensions may occur, and in the case of evaporating a base material and depositing it on an opposing substrate, it may cause variations in film quality and film thickness.

[0007]

According to a first aspect of the present invention, there is provided a laser irradiation apparatus for realizing the stability of energy of a laser beam applied to a substrate surface. With the configuration of this device, it is possible to measure the energy of the laser irradiation unit whenever necessary, and analyze the measured laser energy and feed it back to laser light output control to calibrate to the desired optimum energy It is possible to do. As a result, stable laser irradiation can always be performed even when the use conditions, environment, and irradiation energy of the laser are changed, and the reliability and stability of the device can be improved.

According to a second aspect of the present invention, there is provided a laser irradiation apparatus which realizes stability of energy of a laser beam applied to a substrate surface. With the configuration of this device, it is possible to measure the energy of the laser irradiation unit whenever necessary, and analyze the measured laser energy and feed it back to laser light transmittance control to obtain the desired optimum energy. Calibration becomes possible. As a result, stable laser irradiation can always be performed even when the use conditions, environment, and irradiation energy of the laser are changed, and the reliability and stability of the device can be improved.

According to a third aspect of the present invention, there is provided a method for constantly and stably irradiating a substrate surface with a laser beam having a desired energy. According to the laser irradiation method of the present invention, immediately before the laser irradiation, in the vicinity of the irradiation part, while changing the output of the laser light while measuring the energy of the laser light, after calibrating the output to the desired laser energy, The output is fixed and the substrate surface is irradiated with a laser. By using such a method, it is possible to always perform stable laser irradiation even when the conditions of use, environment, and irradiation energy of the laser are changed, and to reduce variations in device characteristics between substrates or lots. Thus, the reliability and stability of the device can be improved.

A laser irradiation method according to a fourth aspect of the present invention realizes a method of stably irradiating a substrate surface with laser light having a desired energy at all times. According to the laser irradiation method of the present invention, in the vicinity of the irradiated part immediately before laser irradiation, the transmittance of the laser optical system was changed while measuring the energy of the laser light, and the transmittance was calibrated so that the desired laser energy was obtained. After that, the transmittance of the laser optical system is fixed and the substrate surface is irradiated with laser. By using such a method, it is possible to always perform stable laser irradiation even when the conditions of use, environment, and irradiation energy of the laser are changed, and to reduce variations in device characteristics between substrates or lots. , Device reliability,
Stability can be improved.

[0011]

(Embodiment 1) A laser irradiation apparatus according to an embodiment of the present invention will be described with reference to FIG.

This apparatus comprises a laser oscillator, a laser output control device, an optical system I having a mechanism for changing the transmittance of laser light, and an optical system I for shaping the laser light into a desired shape.
I, a vacuum chamber provided with a laser light introduction window for introducing laser light while holding the substrate in a vacuum or a predetermined gas atmosphere, a power meter for measuring the output of laser light, position control of the substrate and the power meter, power A main component is a control PC (or PLC) that takes in the output of the meter and controls the laser output control device to obtain the desired output. The power meter is provided with a shutter for preventing fogging due to adhesion of evaporant generated slightly during substrate processing.

According to the configuration of the present apparatus, it is possible to directly measure the energy of the laser beam on the substrate surface at any time. Furthermore, even if energy fluctuations occur on the surface of the irradiated substrate due to aging of optical components constituting the optical system, changes in transmittance characteristics due to temperature, and fogging of the optical components, which have been problems in the past, the state is measured each time Then, an appropriate irradiation energy can be obtained by feeding back to the output of the laser beam. As a result, laser usage conditions, environment,
It was possible to always perform stable laser irradiation even when the irradiation energy was changed, and it was possible to improve the reliability and stability of the device.

(Embodiment 2) A laser irradiation apparatus according to a second embodiment of the present invention will be described with reference to FIG.

This apparatus comprises an optical system I having a laser oscillator, a laser output control device, a transmittance control device for changing the transmittance of laser light, an optical system II for shaping the laser light into a desired shape, and a substrate being evacuated. Vacuum chamber with laser light introduction window and measurement window for introducing laser light, power meter for measuring laser light output, substrate position control, power meter Control PC (or PLC) that controls the transmittance control device to take in the output and obtain the desired output
Is the main component. The measurement window is provided with a shutter for preventing fogging due to adhesion of evaporative substances that are slightly generated during substrate processing.

According to the configuration of the present apparatus, it is possible to measure the energy of the laser beam on the substrate surface at any time, though indirectly. Furthermore, even if energy fluctuations occur on the surface of the irradiated substrate due to aging of optical components constituting the optical system, changes in transmittance characteristics due to temperature, and fogging of the optical components, which have been problems in the past, the state is measured each time Then, an appropriate irradiation energy can be obtained by feeding back to the output of the laser beam. As a result, it became possible to always perform stable laser irradiation even when the use conditions, environment, and irradiation energy of the laser were changed, thereby improving the reliability and stability of the device.

(Embodiment 3) A laser irradiation apparatus according to another embodiment of the present invention will be described with reference to FIG.

This apparatus comprises an optical system I having a laser oscillator, a laser output control device, a transmittance control device for changing the transmittance of laser light, an optical system II for shaping the laser light into a desired shape, and a substrate being evacuated. Vacuum chamber with laser light introduction window for introducing laser light inside, or in a predetermined gas atmosphere, power meter for measuring laser light output, power meter for laser light just before laser light introduction window Control PC that controls the reflection mirror that reflects the light, the position of the substrate, and the control of the transmittance control device that takes in the output of the power meter and obtains the desired output.
(Or PLC) is the main component. The reflection mirror is attached to the reflection mirror moving mechanism so as to be movable at the time of irradiating the substrate.

According to the configuration of the present apparatus, it is possible to measure the energy of the laser beam on the substrate surface at any time, though indirectly. Furthermore, even if energy fluctuations occur on the surface of the irradiated substrate due to aging of optical components constituting the optical system, changes in transmittance characteristics due to temperature, and fogging of the optical components, which have been problems in the past, the state is measured each time Then, an appropriate irradiation energy can be obtained by feeding back to the output of the laser beam. As a result, it became possible to always perform stable laser irradiation even when the use conditions, environment, and irradiation energy of the laser were changed, thereby improving the reliability and stability of the device.

(Embodiment 4) A laser irradiation apparatus according to a third embodiment of the present invention will be described with reference to (FIG. 1) and (FIG. 4).

After placing the substrate on the substrate holder, the power meter is first moved to the laser irradiation position. After oscillating the laser and warming up for a certain period of time, measure the output of the laser at the irradiation position and send the data to the control PC. Calculate the laser energy on the substrate irradiation surface with the control PC. Calculate the difference from the laser energy preset on the control PC. If the difference is out of the predetermined range, the output setting of the laser output control device is changed. The output of the power meter is measured, and when the laser energy falls within a predetermined range, the output setting is fixed at the value at that time. The measurement of the output of the power meter is continued for a certain period of time, and if the output is not out of the predetermined range, the output setting is fixed. If the value is out of the predetermined range, the process is repeated again to determine the output setting. The laser irradiation on the substrate is started immediately with the output setting kept as it is.

When the energy to be applied to the substrate is changed, or when the laser irradiation is interrupted due to the replacement of the substrate or the like, the above steps are repeated as necessary. By using such a method, when the conditions with different irradiation energies are mixed, when the time intervals of the substrates to be processed are not uniform, or when the substrate is processed, the laser is generated by the deposition of a small amount of evaporation from the substrate. The laser output can be calibrated each time, even if the light introduction window gradually becomes cloudy, for example, which has been the cause of the variation in the energy of the laser light applied to the substrate surface and the change over time. As a result, the reliability and stability of the device can be improved.

(Embodiment 5) A laser irradiation apparatus according to a fourth embodiment of the present invention will be described with reference to (FIG. 2) and (FIG. 5).

After the substrate is placed on the substrate holder and evacuated, hydrogen gas is introduced from a gas inlet to adjust the pressure to a predetermined value.
The substrate holder driving mechanism is operated so that the laser light emitted from the optical system II passes through the laser light introduction window and the measurement window and enters the power meter. After oscillating the laser at a constant output and warming up, measure the output of the laser measured with a power meter and send the data to the control PC. Calculate the laser energy on the substrate irradiation surface with the control PC. Calculate the difference from the laser energy preset on the control PC. If the difference is out of the predetermined range, the control unit controls the transmittance control mechanism of the laser light incorporated in the optical system I to change the transmittance. The output of the power meter is measured, and when the laser energy falls within a predetermined range, the transmittance setting is fixed to the value at that time. The measurement of the output of the power meter is continued for a certain period of time, and if it does not deviate from a predetermined range, the transmittance setting is fixed. When the value is out of the predetermined range, the process is repeated again to determine the transmittance setting. With the transmittance set as it is, laser irradiation to the substrate is started immediately.

When irradiating the substrate, the shutter on the measurement window is closed to prevent the measurement window from fogging due to evaporation generated slightly from the laser irradiation surface.

When the energy applied to the substrate is changed, or when the laser irradiation is interrupted due to the replacement of the substrate or the like, the above steps are repeated as necessary. By using such a method, when the conditions with different irradiation energies are mixed, when the time intervals of the substrates to be processed are not uniform, or when the substrate is processed, the laser is generated by the deposition of a small amount of evaporation from the substrate. The laser output can be calibrated each time, even if the light introduction window gradually becomes cloudy, for example, which has been the cause of the variation in the energy of the laser light applied to the substrate surface and the change over time. As a result, the reliability and stability of the device can be improved.

[0027]

According to the laser irradiating apparatus and the laser irradiating method of the present invention, it is possible to always perform stable laser irradiating even when the use condition, environment and irradiation energy of the laser are changed. , Stability can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a schematic configuration of a laser irradiation apparatus according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating a schematic configuration of a laser irradiation apparatus according to a second embodiment of the present invention.

FIG. 3 is a conceptual diagram showing a schematic configuration of a laser irradiation apparatus according to a third embodiment of the present invention.

FIG. 4 is a conceptual diagram showing a schematic system flow of a laser irradiation method according to a fourth embodiment of the present invention.

FIG. 5 is a conceptual diagram showing a schematic system flow of a laser irradiation apparatus according to a fifth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Output control device 3 Optical system I 4 Optical system II 5 Laser introduction window 6 Substrate 7 Substrate holder 8 Driving device 9 Exhaust system 10 Gas introduction port 11 Flow controller 12 Power meter 13 Shutter 14 Control PC (PLC)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihisa Taketomi 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 5F052 AA02

Claims (4)

[Claims] An apparatus for oscillating a laser having a specific wavelength,
A device for changing the output of the laser light, an optical device for controlling the laser light to a desired shape, and a structure for introducing the laser light to the substrate surface while holding the substrate in a vacuum or in an atmosphere replaced with a specific gas A laser irradiation device having at least a device having: a means for measuring laser energy in the vicinity of the substrate surface; a means for analyzing the measured laser energy; and a means for adjusting the output of laser light based on the analyzed laser energy. A laser irradiation device, comprising: 2. An apparatus for oscillating a laser having a specific wavelength,
An optical device for controlling the transmittance of the laser light to a desired value,
A laser irradiation device having at least an optical device for controlling a laser beam into a desired shape, and a device having a structure for introducing a laser beam onto the substrate surface while holding the substrate in a vacuum or in an atmosphere replaced with a specific gas. At
A laser irradiation apparatus comprising: means for measuring laser energy in the vicinity of the substrate surface; means for analyzing the measured laser energy; and means for adjusting the transmittance of laser light based on the analyzed laser energy. 3. A method for modifying a thin film by irradiating the substrate surface with a thin film having a property of absorbing laser light in a vacuum or in an atmosphere replaced with a specific gas with the laser light. Immediately before laser irradiation on
Changing the laser output until the desired energy is obtained while measuring the laser energy in the vicinity of the substrate in advance, fixing the laser output when the desired energy is obtained, and irradiating the laser to the substrate surface. Laser irradiation method. 4. A method for modifying a thin film by irradiating the substrate surface with a thin film having a property of absorbing laser light in a vacuum or in an atmosphere replaced with a specific gas with the laser light, Immediately before laser irradiation on
The transmittance is changed in the laser optical system until the desired energy is obtained while measuring the laser energy in the vicinity of the substrate in advance, and when the desired energy is obtained, the transmittance of the optical system is fixed, and the laser irradiation on the substrate surface is performed. Performing a laser irradiation.