JP3300809B2 - Micromachining method using super-resolution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention condenses light energy in a region on the order of nanometers and obtains a high energy density. The present invention relates to a micromachining method using super-resolution for machining a small area.

[0002]

2. Description of the Related Art As a technique for processing a minute area on the order of nanometers, there is a photoetching method (lithography method). In this method, X
It uses rays, electron beams, or light. In these various lithography methods, it is possible to process a shape on the order of nanometers on a workpiece, but it is necessary to prepare a mask pattern reflecting a processing pattern of each product in advance. Further, in these methods, energy is simultaneously applied to a large area of the workpiece through the designed mask pattern. For this reason, it is suitable for processing a large area finely in a short time, but it is difficult to form a local shape change with good controllability.

[0003] Further, as a technique for processing a similar minute area, there are an electron beam drawing method in which an electron beam is scanned to directly perform processing, and a method in which high-power laser light is condensed by a lens or a mirror. However, the above-mentioned electron beam lithography requires processing in a high vacuum. For this reason, clean fine processing without mixing of impurities can be performed. However, not only is there a restriction that a workpiece is placed in a vacuum chamber for processing, but also a reaction occurs with an atmospheric gas in a processed portion of the workpiece. It is difficult. On the other hand, a high energy density can be obtained even if a high-power laser beam is focused only by an existing optical system. However, with this method of collecting and using high-power laser light, it is possible to focus only on the order of the wavelength of the irradiated laser light, and therefore, it is not possible to perform minute processing on the order of nanometers.

[0004] Further, in machining using a conventional hard tool, it is possible to machine a region of about a micrometer, but it is difficult to machine a minute region of the order of nanometers. Although a minute region can be processed by etching using ions, it is difficult to control the position of the processing, and there is a disadvantage that the processing requires time.

[0005]

The technical problem of the present invention is to use a super-resolution technology of light as a method for obtaining a high energy density in a nanometer-order region, and to condense light to a wavelength or less. Accordingly, it is an object of the present invention to provide a micromachining method capable of machining a minute region on the order of nanometers to micrometer. Another technical object of the present invention is to provide a method for processing a minute region which does not require a mask pattern used in various lithography techniques and which does not require processing in a high vacuum such as an electron beam lithography method. To provide. Another technical problem of the present invention is that, since processing in a high vacuum is not required as described above, a reaction between an atmospheric gas and a processing object is caused to generate a new compound in a minute region. Accordingly, it is an object of the present invention to provide a processing method capable of performing a function imparting processing.

[0006] In order to solve the above-mentioned problems, a micromachining method using super-resolution according to the present invention generates light of a ring mode laser or a laser in which a ring-shaped energy distribution is divided by a resonator, or a hologram. The light is split into an annular shape or a plurality of dots using light, and the light is combined by interference at a light-collecting point on the object to be processed by a condenser lens or mirror to form light with high light-collecting properties and high energy density. It is characterized by processing an image and processing a minute area on the order of nanometers to micrometer.

In the above-mentioned micro-machining method, it is effective to use only the high-strength portion at the center among the ring-shaped interference fringes appearing around the focal point due to interference. However, only the high-strength portion is used. As a method for this, by controlling the coherence of the light, the intensity ratio of the light at the high intensity portion at the center of the interference fringe and the light at the peripheral portion outside the interference fringe is increased, so that the intensity at the peripheral portion does not affect the processing. It is appropriate to have. In the above-described micromachining method, light that is formed into a point or a line at a high energy density can be applied to a stationary processing object or processed by scanning relative to the processing object.

In the above-described micro-machining method according to the present invention, the spatial frequency region of light is divided, and the divided spatial frequency regions are combined to form an image, thereby obtaining an image having a high energy density in a region on the order of nanometers. By using the super-resolution technology described above, it is possible to process a minute region on the order of nanometers to micrometers by condensing light to the wavelength or less. As the energy source, a laser beam having high coherence, a wavelength of several hundred nanometers, and an output of at least 10 mW, preferably several W or more is used. Ring to split the spatial frequency domain of light
It is possible to selectively use a method using light having a shape energy distribution, a method using an annular or a plurality of point lights generated using a hologram, and the like.

In the above-mentioned micro-machining method, interference fringes are observed around the converging point due to light interference. In the processing, a high intensity portion at the center of the interference fringes is used. In the control, at least the energy density at the center is several times the energy density at the periphery,
Desirably, it should be 10 times or more. In coherence control, the wavelength component can be controlled using a wavelength conversion crystal or the like, and the phase component can be controlled by changing the refractive index of a part of a lens or a mirror. In addition to the coherence control, in order to use the high intensity portion at the center of the interference fringe, there is a method of physically cutting off the light in the peripheral portion with a mask or the like.

[0010] Further, in the above-mentioned micromachining method, machining in a high vacuum is not required and the atmosphere can be selected. By generating a new compound in a minute region on the order of meters, it is possible to perform a function imparting process. The light having a high energy density obtained in this way is directly irradiated on the object to be processed or scanned on the object to be processed. A method of scanning the object to be processed is also an effective method. At that time, light can be condensed into a point or a line in a region on the order of nanometers and used. For this reason, it does not require a mask pattern used in lithography technology, and does not require processing in a high vacuum unlike the electron beam lithography method, and forms and processes local shape changes with good controllability. It becomes possible.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 conceptually shows an embodiment of a micro-machining method of the present invention for processing a region from a nanometer order to a micrometer order using a super-resolution technique of light. Things. Since processing with light requires a high energy density, the light beam 1 used as an energy source has high energy,
It is desirable to use laser light having a uniform wavelength and phase. In order to obtain super-resolution, the spatial frequency region of light is divided into several light beams 1 by a splitting optical device 2 and condensed at a converging point (processed region) 4 on a processing target 3. It is necessary to combine the divided components by interference to form an image with high light-collecting properties.

Several methods are conceivable for dividing the spatial frequency region of light in the dividing optical device 2. This example is shown in FIGS. 1 and 2A to 2C. FIG. 1 shows a case where a part of an optical device 2 including a lens and a mirror used for light collection is shielded by a light shielding film 2a or the like. FIG. 2A shows a case in which light 11 having a ring-like energy distribution generated by a ring mode laser 10 is used, and FIG.
The light flux 12 is formed into an annular or plural point-like lights 14a,
14B illustrates a case where the image is divided into 14b. These split lights are combined by a condensing lens or a mirror by interference at a converging point 4 on a processing target 3 as shown in FIG. 1, and a plurality of lights are combined as shown in FIG. 2C. The light can be condensed by the optical device 15 including a condensing lens or a mirror.

[0013] In super-resolution, light is split and then combined by interference, so that interference fringes are observed around the focal point. In order to process an extremely small area smaller than the wavelength of light, it is desirable to use only the central high-intensity portion of the interference fringes and cut the rest. To this end, it is effective to increase the intensity ratio between the central portion and the peripheral portion so that the peripheral portion does not affect the processing. Given this intensity ratio, a method of controlling light coherence is suitable. In this coherence control, the wavelength component can be controlled using a wavelength conversion crystal or the like, and the phase component can be controlled by changing the refractive index of a part of a lens or a mirror. In addition, there is a method of physically cutting off light in the peripheral portion by using the mask 5 shown in FIG. The problem when using this mask 5 is that
This is the distance d between the mask 5 and the workpiece 3. This distance d needs to be on the order of the wavelength of the light to be used so that light passing through the mask 5 does not cause diffraction and affect the processing target 3.

Next, embodiments of the present invention will be described more specifically. For example, when a laser beam of 1 W at a wavelength of about 500 nm is condensed by the super-resolution technique, the energy that can be condensed is estimated to be about 1/1000 of the oscillation energy in consideration of the energy loss in the optical system.
The energy of 4 × 10 ⁷ W / cm ² can be applied to a region of about m. This energy density exceeds 1 × 10 ⁶ W / cm ² , which is said to be the energy density required for processing metals and the like.

In order to divide the spatial frequency range of light in order to obtain super-resolution of light, the above-mentioned ring mode laser, a method using light having a ring-shaped energy distribution by a resonator, a hologram, There is a method of using an annular or a plurality of point-like lights generated by using a method, a method of shielding a part of a condenser lens or a mirror, and a method of splitting the light and condensing the light by a plurality of lenses or a mirror. It is effective that the lens or mirror used at this time has a short effective focal length.

When controlling the coherence of light when using the high-intensity portion at the center of the interference fringe observed at the focal point by the super-resolution technique, the energy density at the center is reduced by the energy density at the peripheral portion. By making it several times, desirably ten times or more, the light in the peripheral part does not contribute to the processing. In this coherence control, the wavelength component is a part of the composition, structure, and shape of the wavelength conversion crystal. It is controlled by changing the above. Further, the phase component is controlled by changing the composition, structure, shape, and the like of a part of the lens and the mirror, and changing the refractive index. In addition, there is a processing method in which light in the peripheral portion is physically cut using a metal film or the like.

The high-energy-density light thus obtained is irradiated directly on a processing point on a processing object or while being relatively moved with respect to the processing object. Can increase the peak power per single pulse or increase the amount of energy per unit time, so that it is a more effective processing method with less thermal influence on the peripheral portion of the processing.

In the micromachining method using super-resolution, as described above, machining in a high vacuum is not required, and the atmosphere of the machining site is not limited. For this reason, it is possible to cause a reaction between the atmospheric gas and the object to be processed by utilizing the local high-temperature and high-pressure state of the processing site, and to change the composition and structure of the specific portion. For example, when a metal is processed in an oxygen atmosphere, an oxide can be formed only in a light irradiation portion. In other words, in this case, portions having different electric resistance values on the order of nanometers can be formed, and a structure exhibiting a quantum mechanical effect called a quantum wire or a quantum dot can be realized.

The light super-resolution technique used in the above-mentioned processing method has already been applied as a technique for observing a change in light due to a difference in the shape or composition of a minute region. Is not used. For this reason,
An optical system for condensing high-energy-density light on a minute region has not been considered in the past. However, the existing super-resolution utilizing technique can be effectively used in designing an optical system utilizing the super-resolution technique when performing the above-described micromachining method.

Here, the processing by the ordinary condensing optical system and the processing by the super-resolution optical system will be compared. For example, when a laser beam of 1 W at a wavelength of about 500 nm is converged to this wavelength order, a normal condensing optical system is as high as 1 × 10 ⁸ W / cm ² in consideration of energy loss in the optical system. Processing can be performed by obtaining an energy density. However, a region smaller than 500 nm on the order of wavelength cannot be processed with this energy density. On the other hand, when the laser light is condensed by the super-resolution technique, the energy that can be condensed is set to about 1/1000 of the oscillation energy in consideration of energy loss in the optical system, and 4 × 10 ⁷ It is possible to input energy of W / cm ² . This energy density is 1 × 10 ⁶ W / cm, which is said to be necessary for processing metals and the like.
The energy density is higher than the energy density of ² and can be processed in an extremely fine region on the order of nanometers as compared with a normal condensing optical system.

[0021] Then, by processing by this method, a structure having a width of several tens of nanometers and a length on the order of micrometers can be formed. Also,
By reacting with the atmospheric gas in this region, a compound such as an oxide or a nitride can be formed in a part of the processing region. As a result, a structure that exhibits a quantum mechanical effect called a quantum wire or quantum dot can be manufactured.
These are photoelectric conversion elements, single electron elements, quantum wiring,
It can be expected as a structure having functions such as a cooling element and a thermal control element using a quantum dot structure, a photo-nanocatalyst, and an electrocatalyst.

[0022]

The microfabrication method of the present invention described in detail above uses a light super-resolution technology as a method for obtaining light with a high energy density in a minute region on the order of nanometers to micrometer. The first feature is that the light is condensed to the wavelength or less. This makes it possible to obtain a processing method for a minute region which does not require a mask pattern used in various lithography techniques and does not require processing in a high vacuum such as electron beam lithography. In addition, since processing in a high vacuum is not required as described above, the function imparting processing is performed by causing a reaction between the atmospheric gas and the processing object to generate a new compound in a minute region. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a view conceptually showing a reference example of a micromachining method according to the present invention.

FIGS. 2A to 2C are explanatory diagrams of division of a spatial frequency domain of light.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light beam 2 splitting optical device 2 a light-shielding film 3 object to be processed 4 focal point (processed area) 5 mask 10 ring mode laser 11 light 12 light flux 13 optical device 14 a, 14 b light 15 optical device

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-123017 (JP, A)

Claims (5)

(57) [Claims] 1. A laser light having a ring-shaped energy distribution divided by a ring mode laser or a resonator is synthesized by interference at a focal point on a processing object by a condenser lens or a mirror, and has a high light-collecting property. A micromachining method using super-resolution, characterized by forming an image as light with a high energy density and processing a minute area from the nanometer order to the micrometer order. 2. Using a hologram to convert light into a ring or a plurality of rings.
And split the light with a condenser lens or mirror.
Combined by interference at the focal point on the processing object
Imaged as light with high energy density
From nanometer order to micrometer order
A micro-machining method using super-resolution, characterized in that the micro-area is machined . 3. A method according to claim 1, wherein, of the ring-shaped interference fringes appearing around the focal point due to interference, only the high intensity at the center is used for processing. A micromachining method using resolution. 4. The method according to claim 3, wherein the method of using only the high intensity at the center of the interference fringes includes controlling the coherence of the light, and controlling the coherence of the center of the interference fringes at the outer periphery of the high intensity light. A micromachining method using super-resolution, characterized in that the intensity of light in a part is increased and the light in a peripheral part is light having an intensity not affecting processing. 5. The method according to claim 1, wherein a light image formed in a point or a line at a high energy density is applied to a stationary object to be processed, or is scanned relative to the object to be processed. Item 5. A micromachining method using super-resolution according to any one of Items 1 to 4.