JP2000202384A - Foreign matter removing method and foreign matter removing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously carry out washing process and inspection process in a semiconductor element fabrication process and to improve the productivity by radiating pulsed laser beam while observing the surface of an object to be treated in the case foreign matter is removed from the foreign matter-bearing object by radiating pulsed laser beam. SOLUTION: In order to clean a substrate by removing foreign matter adhering to the substrate to be used for fabricating a semiconductor element, a liquid crystal display element, and the likes, pulsed laser beam 2 is radiated to a substrate 4 from a pulse laser 1 to thermally expand the part of the substrate 4 radiated with the pulsed laser and fine particles are parted from the surface of the substrate 4. At this time, by a scanning electron microscope 6, electron beam radiated out of an electron gun 10 is converged by a lens-barrel 11 and radiated to the substrate 4 and the secondary electrons generated out of the substrate 4 are detected to observe the surface image of the specimen. The pulsed laser light 2 is radiated to the observation point of the surface of the substrate 4 by the microscope 6, so that the situation of removing foreign matter adhering to the surface of the substrate 4 can be displayed on a monitor 9 and whether or not the foreign matter is removed can be confirmed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing foreign substances adhered to a reticle (also referred to as a mask) and a substrate for producing a semiconductor element or a liquid crystal display element and cleaning the same.

[0002]

2. Description of the Related Art In a process for producing a fine circuit pattern of a semiconductor device or a liquid crystal display device, foreign matters adhering to a reticle, a substrate or the like cause defects of the fine circuit pattern. Due to this defect, the functions of the semiconductor element and the liquid crystal display element are impaired, resulting in defective products. At present, foreign matter adhering to a substrate or the like is removed by wet cleaning with a liquid utilizing a chemical effect. In recent years,
A cleaning method with fewer steps than wet cleaning is desired,
Cleaning methods and equipment in dry environments are being developed. As such an apparatus, an apparatus for removing fine particles by irradiating a reticle with a pulsed laser beam is disclosed in Japanese Patent Publication No. 6-9 / 1994.
5510. This device irradiates the surface of the reticle with pulsed laser light to evaporate the fine particles attached to the reticle surface, or to separate the fine particles from the reticle surface by acceleration generated by the rapid thermal expansion of the fine particles or the reticle surface. It is to be removed. Further, when a water film is attached to the surface of the substrate to be cleaned and is irradiated with a laser beam, the effect of the force generated by rapid evaporation of the water on the substrate surface is added, and the removal effect is further increased. The JournalofAppliedPhiy
sicsVol. 71, p3515 (1992).

[0003]

However, in the above-described prior art, it is not possible to confirm whether or not foreign matter has been removed during the cleaning. Therefore, after the cleaning step, a step of checking whether or not the cleaning has been performed reliably is performed. Is required. If it cannot be removed in a single cleaning step, a further cleaning step and an inspection step must be performed, which has the disadvantage that productivity is reduced and costs are increased. The present invention has been made in order to solve the problems of the technology, and an object of the present invention is to provide a foreign matter removing method and a foreign matter removing apparatus capable of simultaneously performing a cleaning step and an inspection step in a dry environment.

[0004]

According to a first aspect of the present invention, there is provided a foreign matter removing method for irradiating a material to which a foreign matter is adhered with a pulse laser beam to remove the foreign matter. A foreign matter removing method is characterized in that a pulsed laser beam is irradiated while observing the surface of the processing material.

In this means, since the state of the surface of the material to be treated is observed while removing foreign matter, there is no need to repeat the cleaning step and the inspection step, thereby increasing the productivity and reducing the element manufacturing cost. Becomes possible. A second means for solving the above problem is that in a foreign matter removing apparatus for removing foreign matter by irradiating a pulsed laser beam to the material to which the foreign matter adheres, a means for observing the surface of the material to be treated is provided. A foreign matter removing apparatus (claim 2).

In this means, since the state of the surface of the material to be treated is observed while removing foreign matter, there is no need to repeat the cleaning step and the inspection step, thereby increasing the productivity and reducing the element manufacturing cost. Becomes possible. A third means for solving the problem is the second means,
The means for observing the surface of the material to be processed is an environmental scanning electron microscope, which is a foreign matter removing device (claim 3).

In this means, since the environment scanning electron microscope is used as the observation optical system, the surface of the material to be processed can be observed well while removing foreign substances.
In addition, since the environmental scanning electron microscope has a high resolution in observation, small foreign matter can be observed with high accuracy.

[0008]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a configuration diagram of a foreign matter removing method and a foreign matter removing apparatus according to an embodiment of the present invention. FIG.
In the figures, 1 is a pulse laser, 2 is a pulse laser beam, 3 is a lens, 4 is a substrate, and 6 is an environmental scanning electron microscope (hereinafter, ESEM). The ESEM 6 includes a substrate holder 5, a laser light introduction window 7, a movable stage 8, a monitor 9,
An electron gun 10, a lens barrel 11 having an electron optical system and the like, and a secondary electron detector 12 are provided.

[0009] A pulse laser beam 2 from a pulse laser 1 is condensed by a lens 3 and irradiated on a substrate 4. Substrate 4
Is mounted on the substrate holder 5, and the substrate holder 5 is mounted on the movable stage 8. The movable stage 8 can move the substrate 4 two-dimensionally, and the substrate 4 is moved to the observation position of the ESEM 6. The pulse laser beam 2 is adjusted so as to be applied to an observation position on the substrate surface. The ESEM 6 is provided with a laser light introduction window 7 so that the observation position can be irradiated with the pulse laser light 2. The introduction window 7 is preferably transparent to the wavelength of the pulse laser 1. The laser 1 has a wavelength of 2.5 μm to 10 μm (Er: YAG
When a laser or a CO2 laser is used, it is preferable to use anhydrous synthetic quartz or zinc selenide. ES
The observation image of the surface of the substrate 4 at the EM 6 is displayed on the monitor 9.

The operation of the foreign matter removing method and the foreign matter removing apparatus having the above-described configurations will be described. When the substrate 4 is irradiated with the pulse laser beam 2 from the pulse laser 1, the irradiated portion of the substrate 4 undergoes rapid thermal expansion. At this time, the fine particles attached to the surface of the substrate 4 are given an acceleration and separate from the surface of the substrate 4. The ESEM 6 is a type of a scanning electron microscope that narrows an electron beam emitted from an electron gun 10 by a lens barrel 11 and irradiates the substrate 4 with the electron beam, detects secondary electrons generated from the substrate 4 and observes a surface image of a sample. However, unlike a normal scanning electron microscope, the sample surface can be observed not in a high vacuum (about 10 ^-3 to 10 ^-4 Pa) but in a water vapor atmosphere (about 200 to 500 Pa). The minute foreign matter adhering to the surface of the substrate 4 is displayed on the monitor 9. Since the ESEM 6 does not use a detector that is sensitive to light as in a normal scanning electron microscope, it is possible to irradiate the sample with light during observation. By irradiating the pulsed laser light to the observation position on the substrate surface in the ESEM 6, the state of removing the foreign matter attached to the substrate surface is displayed on the monitor 9, and it is possible to confirm whether or not the foreign matter has been removed. it can. Since the substrate 4 can be moved two-dimensionally by the movable stage 8, the removal operation can be performed while observing foreign substances in the entire region of the substrate surface. ESEM6 can observe a sample in a water vapor atmosphere, so by lowering the temperature of the sample,
The sample surface can be dewed. Also in the present invention, the effect of removing foreign substances can be improved by cooling the substrate and irradiating the substrate with the film of the adsorbed water and irradiating the substrate with a pulsed laser beam. As described above, in the configuration of the present invention, it is possible to simultaneously perform the removal of the foreign matter and the inspection. In the present invention, the means for observing the substrate surface is ES
Although EM was used, other means may be used as long as the laser irradiation does not affect the observation of the substrate surface 4.

As the pulse laser 1, an excimer laser such as a KrF laser, an ArF laser, and a XeCl laser, a YAG laser, and a nitrogen laser can be used. Since these lasers are hardly absorbed by water, a water film is usually formed on the substrate surface and foreign matter is not removed, so that the inside of the ESEM 6 may be at a high vacuum as usually used. When a water film is formed on the above-mentioned substrate surface to improve the effect of removing foreign substances, a wavelength (about 2.5 μm to 10 μm) having absorption in water, such as a carbon dioxide laser or an Er: YAG laser, is used. It is preferable to use The intensity of the pulse laser beam 2 is desirably such that the surface of the substrate 4 is not destroyed, and may be several hundred mJ / cm 2 per pulse.

In this embodiment, an ESEM is used as an observation means.
Was used. As observation means, ESEM
However, other observation means can be used as long as the required resolution is obtained. For example, an optical microscope can be used. However, when an optical microscope is used, the light for cleaning may obstruct the observation of the removal of foreign matter. In such a case, it may be configured to observe the light through a filter that cuts the wavelength to be cleaned.

[0013]

As described above, according to the foreign matter removing method and foreign matter removing apparatus of the present invention, the cleaning step and the inspection step can be performed simultaneously in the manufacturing steps of the semiconductor element and the liquid crystal display element, so that the productivity is improved. Higher and lower costs.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a particle removing device according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pulse laser 2 ... Pulse laser light 3 ... Lens 4 ... Substrate 5 ... Substrate holder 6 ... Environmental scanning electron microscope (ESEM) 7 ... Laser light introduction window 8 ... Movable stage 9 ... Monitor 10 ... Electron gun 11 ... Barrel 12 Secondary electron detector

Claims (3)

[Claims] In a foreign matter removing method for removing a foreign matter by irradiating a pulsed laser beam to a material to which a foreign matter adheres, the pulsed laser light is irradiated while observing the surface of the material to be treated. A method for removing foreign matter, comprising: 2. A foreign matter removing apparatus for removing foreign matter by irradiating a pulsed laser beam to a material to which the foreign matter has adhered, comprising means for observing the surface of the material to be treated. . 3. A foreign matter removing apparatus according to claim 1, wherein said means for observing the surface of said workpiece is an environmental scanning electron microscope.