JPH1064862A - Cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device which can prevent the generation of parts that are difficult to be cleaned, even when an object having uneven surface is subject to cleaning, or can clean sufficiently the surface of the object without damaging a thin film or a micro structure that is formed on the object, for example, reticles. SOLUTION: A cleaning device which cleans the surface of an object 201 to be cleaned by removing foreign matters adhered to its surface, is provided with liquid film formation mechanisms 202, 203, 204, 205, 221, 222, and 223 which form liquid films on the surface of the object through dewing, and a pulse light irradiation mechanism which emits a pulse light 210 to the surface. In such a state where the liquid film is formed on the surface by the liquid film formation mechanism, the surface to be cleaned is irradiated with a pulse light through the pulse light irradiation mechanism so as to evaporate the liquid film for removal of the foreign matters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cleaning apparatus for cleaning an object surface such as a wafer surface and a reticle surface in a semiconductor exposure process, for example.

[0002]

2. Description of the Related Art When fine processing such as a circuit pattern is performed on a silicon wafer by lithography, dust (foreign matter) such as fine particles adhered to the surface of the reticle or the wafer greatly hinders the processing and lowers the product yield. The particle size of the dust allowed at this time is a fraction or a tenth of a circuit pattern, and therefore, cleaning them is an important technique.

[0003] As a method of cleaning a reticle or a wafer, there are a method of wiping with a cloth or the like which does not generate dust, and a method of applying ultrasonic vibration in a state of being immersed in a liquid. The product is immersed in a mixed solution of hydrochloric acid, sulfuric acid, hydrofluoric acid, aqueous hydrogen peroxide, ammonium hydroxide and the like. In addition, as a cleaning method using irradiation with pulsed laser light, irradiation with pulsed laser light induces vibration of fine particles adhering to the surface of the object to be cleaned, and a method for removing the particles by reducing the adhesive force, water, or water. A method has also been proposed in which a thin film of water is formed by spraying water vapor on the surface to irradiate a laser beam to instantaneously evaporate water and at the same time peel off fine particles.

In a reticle used in optical lithography, a pellicle, which is a transparent film, is disposed on both sides of a mask pattern at a certain distance in order to eliminate the influence of fine particles adhering during exposure. ing. Since the fine particles adhering to the pellicle form only a blurred image on the imaging surface, the influence on the pattern to be exposed as a result can be reduced.

[0005]

As the minimum line width of a pattern formed on a wafer is reduced, the allowable maximum diameter of attached dust is also reduced. Generally, particles having a smaller diameter are more present and have a larger adhesive force with respect to the mass, so that it is difficult to remove them from the wafer, which is a problem.

Further, when a cleaning object (object) such as a wafer is immersed in the cleaning liquid, the dirt contained in the cleaning liquid adheres, and the dirt once removed is re-adhered. There is a problem that a portion is easily generated. Moreover, when irradiating pulsed laser light to remove attached fine particles, it is more effective to have a liquid film on the surface of the object, so water or water vapor is sprayed immediately before irradiation with the pulsed laser light. When cleaning a thin film or a fine structure formed on an object, there is a possibility that the thin film or the fine structure is destroyed by the spraying,
There is a problem that the control is also complicated.

Further, when lithography is performed using light or an electron beam in a shorter wavelength region than vacuum ultraviolet light in order to further reduce the minimum line width of a pattern, it is difficult to form a thin film using a transparent substance. For this reason, there is a problem that a pellicle cannot be used as a reticle. The effect of the fine particles attached to the reticle affects all patterns using the reticle. Therefore, when performing lithography using light or an electron beam in a shorter wavelength region than vacuum ultraviolet light, cleaning of the reticle is also an important issue.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and problems, and it is intended to prevent the generation of a portion which is difficult to clean even when cleaning the surface of an object having irregularities, and to prevent the formation of the surface on the object. An object of the present invention is to provide a cleaning apparatus which can clean the surface of an object without destroying a thin film or a fine structure, and which can sufficiently clean a reticle, for example.

[0009]

Therefore, the present invention firstly provides a cleaning apparatus for cleaning by removing foreign substances adhering to the surface of an object to be cleaned, wherein a liquid film is formed on the surface by condensation. A liquid film forming mechanism, and a pulse light irradiating mechanism for irradiating pulse light toward the surface to be cleaned, and in a state where a liquid film is formed by the liquid film forming mechanism, a pulse is applied to the surface to be cleaned by the pulse irradiating mechanism. A cleaning device (claim 1), wherein the foreign matter is removed by irradiating light to evaporate the liquid film.

[0010] The present invention is also directed to a second aspect, wherein the liquid film forming mechanism comprises: a cooling mechanism for cooling the object to be cleaned; a temperature / humidity control mechanism in a space for accommodating the object to be cleaned; And a gas introduction mechanism for introducing a dew-condensation material gas into the cleaning device. Further, the present invention provides a cleaning apparatus according to claim 2, wherein the liquid film forming mechanism further includes a mechanism for heating the object to be cleaned and / or a mechanism for controlling the temperature and humidity of the gas. (Claim 3) "is provided.

Further, the present invention provides a liquid film forming mechanism having a liquid film detecting mechanism for detecting an amount or a film thickness of a liquid film formed on a surface to be cleaned to be irradiated with the pulse light. The cleaning device according to claims 1 to 3 (claim 4) "is provided. Further, the present invention provides a fifth aspect of the present invention: "a cleaning apparatus according to any one of claims 1 to 4, wherein a foreign substance detection mechanism for detecting foreign substances attached to the surface of the object to be cleaned is provided." I do.

In the sixth aspect of the present invention, there is provided a cleaning apparatus according to any one of claims 1 to 5, further comprising an irradiation position adjusting mechanism for adjusting an irradiation position of the pulse light on the surface to be cleaned. Item 6) is provided.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cleaning apparatus according to the present invention includes a liquid film forming mechanism for forming a liquid (eg, water or alcohol) film by condensation on a surface of an object to be cleaned, and irradiates pulse light toward the surface. A pulse light irradiating mechanism for irradiating the surface of the object to be cleaned with pulse light by the pulse light irradiating mechanism in a state where the liquid film is formed on the surface of the object by the liquid film forming mechanism. The foreign matter can be effectively removed by evaporating the reticle, so that, for example, the reticle can be sufficiently washed.

Since the liquid film forming mechanism according to the present invention forms a liquid film due to dew condensation on the surface of the object to be cleaned, the liquid film is formed even when the surface to be cleaned has irregularities (for example, microstructure irregularities). It is possible to remove (clean) foreign substances by irradiating pulsed light effectively by forming the entire surface without leakage. Further, the liquid film forming mechanism according to the present invention forms a liquid film due to dew condensation on the surface of the object to be cleaned (forms it very statically), so that a thin film or a fine structure formed on the surface of the object to be cleaned is formed. A liquid film can be formed on the thin film or the fine structure without destroying the particles, and the foreign matter can be effectively removed (cleaned).

That is, according to the cleaning apparatus of the present invention, it is possible to prevent the occurrence of portions that are difficult to clean even when cleaning the surface of an object having irregularities, and to prevent the thin film and the fine structure formed on the object from being destroyed. The surface of the object can be cleaned, for example, the reticle can be sufficiently cleaned. Further, according to the cleaning apparatus of the present invention, there is no need to immerse the object to be cleaned in the cleaning liquid, so that there is no risk of contamination by fine particles and the like contained in the cleaning liquid, and there is very little risk of redeposition of the fine particles once removed. .

A component of a liquid (for example, water) film formed on the surface of an object to be cleaned (for example, a Si wafer) is a pure liquid (for example, pure water) generated by dew condensation, and therefore does not contribute to contamination. . Furthermore, since the dew condensation material (for example, water) may be supplied as steam, it is not necessary in a large amount, the supply is easy, and the control of the entire cleaning apparatus is simple.

The liquid film forming mechanism according to the present invention includes, for example, a cooling mechanism for cooling an object to be cleaned, a temperature and humidity control mechanism in a space for accommodating the object to be cleaned, and / or a dew condensation material in the space. A device having a gas introduction mechanism for introducing gas can be used (claim 2). FIG. 1 shows an example of a cleaning apparatus provided with such a cooling mechanism and a temperature and humidity control mechanism as a partial configuration diagram in the vicinity of a laser beam irradiation position.

A Si wafer 101 which is an example of an object to be cleaned
Is placed on the base 102. The base 102 is the cooler 1
03, and the Si wafer 101 is also cooled by cooling the base 102. Here, the base 102 and the cooler 103 constitute a cooling mechanism according to the present invention. When the temperature of the Si wafer 101 decreases, a water film is formed on the wafer surface due to dew condensation. Here, the temperature and humidity in the space in which the Si wafer is stored (or in the peripheral space of the Si wafer) can be controlled by a temperature and humidity control mechanism. The amount and thickness of water adhering to the wafer surface (the amount and thickness of the formed water film) can be controlled.

After irradiating the laser beam 110, a water film is formed on the surface of the Si wafer by dew condensation to form a water film of an amount or thickness capable of removing the adhered particles (foreign matter) more effectively or most effectively. When the light 110 is irradiated, attached particles (foreign matter) are effectively removed together with the evaporation of water. The liquid film forming mechanism according to the present invention is provided with a heating mechanism for the object to be cleaned and / or the gas so that the temperature of the object to be cleaned can be quickly controlled or the controllability of the formation of the liquid film is improved. It is preferable to further include a temperature / humidity control mechanism (claim 3).

As described above, the amount and thickness of the liquid film formed on the surface of the object to be cleaned can be controlled by the cooling temperature and the cooling time of the object to be cleaned by the cooling mechanism. In order to form a liquid film of an amount or thickness capable of effectively or most effectively removing adhered particles (foreign matter), the liquid film forming mechanism according to the present invention is formed on a surface to be cleaned. It is preferable that a liquid film detecting mechanism for detecting the liquid film amount or liquid film thickness is provided.

It is preferable that the cleaning apparatus of the present invention is provided with a foreign substance detecting mechanism for detecting foreign substances attached to the surface of the object to be cleaned, in order to more accurately prevent the generation of residual cleaning. Further, the cleaning apparatus of the present invention includes an irradiation position adjusting mechanism for adjusting (changing) the irradiation position of the pulse light on the surface to be cleaned so that the object to be cleaned can be efficiently and completely cleaned. Preferably, it is provided (claim 6).

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

[0023]

FIG. 2 is a schematic structural view of a cleaning apparatus according to this embodiment. The Si wafer (an example of the object to be cleaned) 201 is the base 2
02. The base 202 includes a heat radiating member 204.
The cooling is performed by a Peltier element 203 (an example of a cooler) that is in contact with the substrate, and the Si wafer 201 is also cooled by cooling the base 202.

The temperature of the substrate 202 is measured by a thermocouple 205 (an example of a temperature measuring device), and the output of the thermocouple 205 is input to a substrate temperature control unit 221. The substrate temperature control section 221 also controls the Peltier element 203 so that the temperature of the substrate can be adjusted. Here, the Peltier element 203, the thermocouple 205, and the substrate temperature control unit 221 that are in contact with the substrate, the heat radiating member 204 constitute a cooling mechanism and a heating mechanism according to the present invention.

The substrate 201 is placed in an airtight container 220, and the humidity and temperature inside the container 220 are measured by the temperature / humidity measuring unit 223 and simultaneously controlled by the temperature / humidity control unit 222. I have. Here, the temperature and humidity measurement unit 223 and the temperature and humidity control unit 222 constitute a temperature and humidity control mechanism according to the present invention.

When the substrate 202 is cooled by the Peltier element 203 and the temperature of the Si wafer 201 is lowered, a film of water is formed on the surface of the wafer due to dew condensation. Since the temperature and humidity in the container 220 are controlled, the Si
The amount and thickness of water adhering to the surface can be controlled by the temperature of the wafer 201 and the cooling time. Further, in the present embodiment, a water film thickness detector (an example of a liquid film detection mechanism) 224
The amount or thickness of the water film that can detect the amount of water adhering to the surface, and more effectively or most effectively remove the adhering particles (foreign matter) when pulsed light is irradiated Can be formed.

In this way, after dew condensation on the surface of the Si wafer enough water to remove the adhered particles more effectively or most effectively when irradiating the laser light 210, the pulse laser light 210 is applied. Irradiate. The pulse laser beam 210 is output light of a KrF excimer laser, and has a time width of 20 ns and an energy per square centimeter of 200 mJ. Dirt such as fine particles attached to the surface of the Si wafer 201 is removed by the pulsed laser light 210.

The laser beam 210 can scan the Si wafer 201 by changing the angle of the reflecting mirror 211, and can irradiate the entire surface or almost the entire surface of the Si wafer 201 (an example of an irradiation position adjusting mechanism). After or during the irradiation of the laser light 210, the S
The fine particles remaining on the surface of the i-wafer 201 are detected by a fine particle detector (an example of a foreign matter detection mechanism) 225, and the formation of a water film and the cleaning by irradiation with the laser beam 210 are continued until the fine particles are no longer detected.

In this embodiment, the entire surface of the Si wafer is cleaned by scanning the laser beam. However, the base on which the Si wafer is placed is placed on a stage, and the entire surface of the Si wafer is cleaned by moving the wafer. May be performed. In addition, the pulsed laser light is converted to KrF
Although the output is an excimer laser, the wavelength is not limited to this, and another pulsed laser beam may be used.

In addition, not only water vapor but also vapor such as alcohol may be contained in the container to form a liquid film on the wafer surface. Further, the pressure in the container is not limited to the atmospheric pressure, and may be pressurized or reduced as long as a liquid film is formed by condensation.
In the present embodiment, the base is cooled by the Peltier element (an example of a cooler), but the cooler is not limited to this. However, in order to quickly control the temperature of the substrate, it is preferable that the substrate includes not only a cooler but also a heater. In the case of a Peltier element, both heating and cooling can be performed by changing the direction of current flow.

[0031]

As described above, according to the cleaning apparatus of the present invention, it is possible to suppress the generation of portions that are difficult to clean even when cleaning the surface of an object having irregularities, and to reduce the thin film formed on the object. It is possible to clean the surface of the object without destroying the microstructure. For example, the reticle can be sufficiently cleaned.

Further, according to the cleaning apparatus of the present invention, there is no need to immerse the object to be cleaned in the cleaning liquid, so that there is no risk of contamination due to fine particles contained in the cleaning liquid, and there is no risk of reattachment of the fine particles once removed. Very little. The component of the liquid (for example, water) film formed on the surface of the object to be cleaned (for example, a Si wafer) is a pure liquid (for example, pure water) generated by dew condensation, and does not contribute to contamination.

Further, since the dew condensation material (for example, water) may be supplied as steam, it is not required in a large amount, the supply is easy, and the control of the entire cleaning apparatus is simple.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of the present invention;
FIG. 4 is a partial configuration diagram of a cleaning device provided with a cooling mechanism and a temperature and humidity control mechanism in the vicinity of a laser beam irradiation position.

FIG. 2 is a schematic configuration diagram of a cleaning apparatus according to an embodiment.

[Explanation of symbols]

 101, 201 Si wafer (an example of an object to be cleaned) 102, 202 Substrate 103 Cooler 203 Peltier element (an example of a cooler or a heater) 104, 204 Heat dissipation member 110, 210 Laser light (an example of pulsed light) 205 Thermocouple (Example of Temperature Measuring Device) 211 Movable Mirror (for Laser Light Scanning) 212 Laser Light Injection Window 221 Substrate Temperature Controller 222 Temperature and Humidity Controller 223 Temperature and Humidity Measuring Unit 224 Water Thickness Detector (Example of Liquid Film Detection Mechanism) ) 225 Particle detector (an example of a foreign substance detection mechanism)

Claims (6)

[Claims] 1. A cleaning apparatus for performing cleaning by removing foreign matter adhering to a surface of an object to be cleaned, comprising: a liquid film forming mechanism for forming a liquid film by condensation on the surface; A pulse light irradiation mechanism for irradiating light, and in a state where the liquid film is formed by the liquid film forming mechanism, the surface to be cleaned is irradiated with pulse light by the pulse irradiation mechanism to evaporate the liquid film. A cleaning device for removing the foreign matter. 2. The liquid film forming mechanism includes: a cooling mechanism for cooling the object to be cleaned; a temperature and humidity control mechanism in a space for accommodating the object to be cleaned; and / or a dew condensation material gas introduced into the space. The cleaning device according to claim 1, further comprising a gas introduction mechanism. 3. The cleaning apparatus according to claim 2, wherein the liquid film forming mechanism further includes a heating mechanism for the object to be cleaned and / or a temperature and humidity control mechanism for the gas. 4. The liquid film forming mechanism according to claim 1, further comprising a liquid film detecting mechanism for detecting an amount or a film thickness of the liquid film formed on the surface to be cleaned to be irradiated with the pulse light. Item 5. The cleaning device according to any one of Items 1 to 3. 5. The cleaning apparatus according to claim 1, further comprising a foreign substance detection mechanism for detecting a foreign substance attached to a surface of the object to be cleaned. 6. The cleaning apparatus according to claim 1, further comprising an irradiation position adjusting mechanism for adjusting an irradiation position of the pulse light on the surface to be cleaned.