JP2006007382A - Method for removing fine particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing fine particles enabling to detect and remove the nano-sized particles adhering to a member used for a microprocessing process. <P>SOLUTION: The method for removing the fine particles 105 adhering to the member 101 used for the microprocessing process comprises a process for controlling a distance between the member and a probe 104 supported by an elastic body 103 based on change of cyclical elastic deformation while cyclically elastic-deforming the elastic body so as to make the probe 104 approach the member, a process for detecting positions of the fine particles adhering to the member based on a distance control amount of the probe, a process for making the probe approach the fine particles adhering to the member based on the result of detecting the positions and removing the fine particles adhering to the member by the probe. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for removing nano-sized fine particles adhering to a member used in a microfabrication process.

Evolution and diversification of lithography technology has progressed, and as emerging lithography technology for exploring new possibilities, Nanoimprint lithography described in Patent Document 1 (hereinafter referred to as nanoimprint lithography), Step and flash imprint lithography described in Patent Document 2 (hereinafter referred to as nanoimprint lithography) Hereinafter, a novel lithography method such as optical nanoimprint lithography) or near-field optical lithography described in Patent Document 3 has been proposed.
These new lithography methods are mainly methods capable of forming a pattern having a size of 100 nm or less, and in any case, a mold or a photomask is 500 nm or less (typically 200 nm or less) with respect to a substrate to be processed or a substrate to be exposed. The information on the mold and mask is transferred to the substrate side.

In addition, an atomic force microscope (hereinafter abbreviated as AFM) has been developed for observing nano-sized fine particles. Using this, a wide variety of observation targets can be observed at a nanoscale resolution from the semiconductor industry to the bio industry. Has been.
The AFM supports a sharp tip with a cantilever that functions as an elastic body, detects elastic deformation of the cantilever due to the force acting between the observation target and the probe, and based on the amount of deformation, determines the shape of the observation target. To observe.
Here, as an elastic deformation detection method,
(1) A contact mode in which the observation object is scanned in two dimensions while contacting the observation object until repulsion occurs.
(2) There is a periodic contact mode in which the cantilever is periodically vibrated and two-dimensional scanning is performed while detecting a change in the periodic vibration state due to a weak force acting between the probe and the observation target.
US Pat. No. 5,772,905 US Pat. No. 6,334,960 US Pat. No. 6,171,730

  However, since molds and photomasks used in (optical) nanoimprint lithography and near-field photolithography as described above are used in close proximity to the substrate to be processed, the nanosize is added to the mold and photomask as the processing process is repeated. Of fine particles may adhere. In such a case, the influence of the adhering portion is transferred to the substrate to be processed, which may cause a processing defect.

  Molds and photomasks for performing nano-size processing are expensive because of their nano-sized structure, and it is desired to develop a technique for removing nano-sized fine particles adhering to the surface. However, it is difficult to detect the attachment position of nano-sized fine particles and it is a more difficult problem to remove, and early realization of an apparatus that solves these problems is required.

  In view of the above problems, an object of the present invention is to provide a fine particle removal method capable of detecting and removing nano-sized fine particles attached to a member used in a microfabrication process.

The present invention provides a fine particle removal method configured as follows.
That is, the method for removing fine particles of the present invention is a method for removing fine particles adhering to a member used in a microfabrication process, wherein a probe supported by an elastic body is elastically deformed while periodically elastically deforming the elastic body. The step of controlling the distance between the member and the probe from the change in the cyclic elastic deformation and bringing it close to the member, and the position of the fine particles attached to the member from the control amount of the distance of the probe And a step of detecting, and based on a result of detecting the position, the probe is brought close to the fine particles attached to the member and the fine particles attached to the member are removed by the probe. It is said.
In the present invention, the step of detecting the position of the fine particles attached to the member is performed by two-dimensionally scanning the probe in the in-plane direction of the member after bringing the probe close to the member. It can be a step of detecting the position of the fine particles adhering to the member from the control amount of the probe during scanning.
Further, in the present invention, the step of removing the fine particles, after detecting the position, stops the periodic elastic deformation of the elastic body, and increases the repulsive force acting on the fine particles of the probe. On the other hand, the step of moving the probe relative to each other to remove the fine particles adhering to the member can be adopted.
In the present invention, the member can be applied to a photomask used in near-field photolithography, a mold used in nanoimprint lithography, or optical nanoimprint lithography.

  ADVANTAGE OF THE INVENTION According to this invention, the removal method of the microparticles | fine-particles which can detect and remove the nanosize microparticles adhering to the member used for a microfabrication process is realizable.

The principle of the method for removing fine particles in the embodiment of the present invention will be described with reference to FIG.
In FIG. 1, 101 is a photomask, 102 is a mask pattern, 103 is a cantilever, and 104 is a probe.
As shown in FIG. 1, a mask pattern 102 formed on a photomask 101 is two-dimensionally scanned in the in-plane direction of the photomask 101 with a probe 104 supported by a cantilever 103 that is an elastic body. .
At this time, the cantilever 103 is vibrated in the normal direction of the photomask 101 surface. In this state, the tip of the probe 104 is brought close to the distance on which the van der Waals force acts on the surface of the photomask 101. Due to the approach of this distance, the vibration state (amplitude and phase) of the cantilever 103 changes under the influence of the van der Waals force. The vibration state is detected, and the position in the photomask surface normal direction of the support portion 107 of the cantilever 103 that supports the probe 104 with respect to the photomask 101 is adjusted so that the vibration state becomes constant. The shape of the irregularities on the surface of the photomask 101 can be detected from the position adjustment amount of the support portion 107 during two-dimensional scanning.
Here, as a method of detecting the amplitude of the vibration in order to detect the vibration state of the cantilever, an optical lever method, an optical interferometer, an electrostatic sensor, or the like can be used.

Here, as an example, a method for detecting the vibration state of the cantilever using the optical lever method and removing the fine particles will be described.
In order to detect the vibration state of the cantilever by the optical lever method, first, a surface opposite to the mask pattern 102 side of the cantilever 103 is irradiated with a laser, and the laser beam reflected by the cantilever 103 is reflected into a two-part sensor (not shown) To introduce. This two-divided sensor is composed of two photodiodes, and the laser light is introduced into the two diodes so as to be substantially uniform.
Next, by applying vibration to the cantilever 103, the stage 106 is driven so that the tip of the probe 104 approaches the surface of the photomask 101 while the cantilever 103 is elastically deformed periodically. When the surface of the cantilever 103 bends, the reflection of the laser light changes, and the proportion of light introduced into the two photodiodes of the two-divided sensor changes. The vibration state is detected by the amount of change in reflection of light due to the amount of deflection, the distance between the probe 104 and the surface of the photomask 101 is controlled, and the probe 104 supported by the cantilever 103 is formed on the photomask 101. After approaching the mask pattern 102, the cantilever 103 is scanned two-dimensionally.
By detecting the vibration state, the position is adjusted so that the vibration state of the cantilever 103 due to the influence of van der Waals force during the two-dimensional scanning becomes constant. As a shape different from the above, fine particles 105 such as dust and contamination existing on the surface of the photomask 101 are detected.

Next, after detecting the fine particles 105, the stage 106 is driven to control the tip of the probe 104 to be at the position of the fine particles 105, and then the vibration of the cantilever 103 is stopped. Further, the support portion 107 of the cantilever 103 is driven in a direction approaching the surface of the photomask 101 to increase the repulsive force acting between the probe 104 and the fine particles 105.
Thereafter, the stage 106 is driven in the in-plane direction of the photomask 101, the tip of the probe 104 is moved relative to the photomask 101, the fine particles 105 are peeled off from the photomask 101 by the mask probe 104, and moved. Remove.

At this time, the magnitude of the repulsive force acting between the probe 104 and the fine particles 105 depends on the magnitude of the adhesion force of the fine particles 105 to the photomask 101, but is generally between 10 ⁻⁷ N and 10 ⁻⁴ N. is there. For example, when the elastic constant in the elastic deformation of the cantilever 103 is 10 N / m, a repulsive force of 10 ⁻⁵ N is applied by bringing the support 107 of the cantilever 103 into contact with the photomask 101 and then bringing it closer to 1 μm. Can be made.
In the present embodiment, the description has been given by taking a cantilever that supports one probe as an example, but the concept of the present invention is not limited to this, and supports at least one probe. There may be at least one cantilever. In the case of using a plurality of probes or a plurality of cantilevers, a plurality of fine particles can be removed at the same time, and the fine particle removal throughput can be improved.

It is a figure explaining the principle of the removal method of the microparticles | fine-particles in embodiment of this invention.

Explanation of symbols

101: Photomask 102: Mask pattern 103: Cantilever 104: Probe 105: Fine particle 106: Stage 107: Support part

Claims (4)

A method for removing fine particles adhering to a member used in a microfabrication process,
The probe supported by the elastic body is controlled to be close to the member by controlling the distance between the member and the probe from the change of the periodic elastic deformation while periodically elastically deforming the elastic body. Process,
Detecting a position of fine particles attached to the member from a control amount of the probe distance;
Based on the result of detecting the position, bringing the probe close to the fine particles attached to the member, and removing the fine particles attached to the member by the probe;
A method for removing fine particles, comprising:   In the step of detecting the position of the fine particles attached to the member, after the probe is brought close to the member, the probe is two-dimensionally scanned in the in-plane direction of the member, and the probe in the two-dimensional scanning is scanned. 2. The method for removing fine particles according to claim 1, wherein the method is a step of detecting the position of the fine particles attached to the member from a control amount.   The step of removing the fine particles, after detecting the position, stops the periodic elastic deformation of the elastic body and increases the repulsive force acting on the fine particles of the probe to move the probe relative to the member. The method for removing fine particles according to claim 1, wherein the fine particle adhering to the member is removed.   The method for removing fine particles according to any one of claims 1 to 3, wherein the member is a photomask used in near-field photolithography, a mold used in nanoimprint lithography, or optical nanoimprint lithography. .

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