JP2012040573A - Microprocessing method of sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microprocessing method of a sample which is capable of achieving processing in nanometer order accuracy without damaging the sample regardless of conductive/insulating properties of the sample, superior in efficiency compared with an conventional method, and capable of shortening processing time and simplifying processing.SOLUTION: Under an ultra-high vacuum, a high electric field is formed at a to-be-worked part of the sample having a sample multi-layer film structure, and the to-be-worked part is irradiated with a laser beam 13 to perform photoexcitation field evaporation, thereby performing microprocessing without damaging an atomic structure of the sample. At this time, it is desirable that an electrode having a pinhole 12 acting as a course of a laser beam is used as an electrode 11a for forming the high electric field. It is desirable to irradiate a pulse laser beam through an optical fiber. Further, it is desirable that the pulse laser beam is used as a laser beam.

Description

  The present invention relates to a method for finely processing a sample having a multilayer film structure. More specifically, for the analysis and evaluation of thin-film solar cells and semiconductor devices, the surface of the sample to be analyzed is cleaned, or fine pattern processing with a spatial resolution of nanometer order can be used. The present invention relates to a fine processing method.

  A conventional technique will be described with reference to FIGS.

  FIG. 1 shows a cross section of an analysis sample in which five layers of thin films 102 to 106 are formed on a silicon substrate 101. When component analysis or structural analysis is performed in the depth direction from the surface of the laminated film in this way, the surface is etched at a low speed while etching the surface by irradiating an ion beam 107 such as argon ions, and the surface appears sequentially. A technique of analyzing by irradiating an X-ray, an electron beam, or a visible light laser is known. X-ray photoelectron spectroscopy is used as a method for measuring the energy of electrons emitted by irradiating X-rays, Auger electron spectroscopy is used as a method for measuring Auger electrons emitted by irradiating electron beams, and visible. Raman scattering spectroscopy is known as a method of dispersing scattered light by irradiation with an optical laser.

  In addition, as a method for analyzing a deep portion from a surface covered with a laminated thin film or an upper thin film, a polishing method is known in which an abrasive grain is used to cut an oblique surface. That is, as shown in FIG. 2, the polishing surface 108 having an angle θ with respect to the surface 109 is cut out. In this method, by setting θ to about 1 degree to 0.1 degree, an area of about 50 to 500 times the thickness can be exposed to the polishing surface 108, so that the analysis area can be expanded and analyzed. It is known as a useful method.

  On the other hand, a method of processing a surface by utilizing the fact that atoms are sucked out by an electric field applied to the surface is also known (see, for example, Patent Document 1). That is, as shown in FIG. 3, the needle probe 112 having a tip diameter of the order of several hundreds of nanometers is arranged on the surface to be analyzed, and a positive voltage is applied to the needle probe 112 side with respect to the sample surface. This is a method of processing the surface by releasing the atoms 113 constituting the sample surface to the needle probe 112 side.

JP-A-5-255870

  However, in the method of etching in the vertical direction from the surface by irradiating with an ion beam, there is a problem of damage to the analysis target due to the beam irradiation. That is, when the analysis target is a single crystal, there is a problem in that ions having momentum are incident to make the crystal amorphous, and physical property information such as a crystal structure is lost. Further, even with the polishing method, there has been a problem that mechanical damage to the analysis target such as polishing scratches and local distortions cannot be avoided.

  In this regard, the method using the needle-like probe as described in Patent Document 1 utilizes the fact that atoms are released to the needle-like probe side by the electric field applied to the surface, so that the ion beam irradiation method or polishing is used. Compared to the method, it is possible to process the surface without causing mechanical damage to the surface and to obtain a fresh analytical surface. However, since the atoms constituting the sample surface are moved to the needle probe side, the moved atoms accumulate on the tip of the needle probe as processing is repeated, and the desired electric field strength or distribution cannot be maintained. There was a problem. In addition, there is a problem that the efficiency is low and the area that can be processed at a time is limited to a very small range. Furthermore, since a tunnel current flowing between the needle probe and the sample is used, there is a problem that it is not suitable for processing an insulating sample.

  Therefore, the object of the present invention is to realize processing with nanometer order accuracy without damaging the sample regardless of whether it is a conductive or insulating sample, and it is superior in efficiency and processing time compared to the conventional method. An object of the present invention is to provide a sample microfabrication method that can be shortened and simplified.

  In order to achieve the above object, according to a first aspect of the present invention, in a method for finely processing a sample having a multilayer film structure without damaging the atomic structure, the portion to be processed of the sample is subjected to ultrahigh vacuum. In addition, the present invention provides a sample microfabrication method characterized by forming a high electric field and irradiating a laser beam to cause photoexcitation electric field evaporation.

  According to the above invention, a high electric field is formed on the processed part of the sample having a multilayer film structure, and the laser beam is irradiated to perform photoexcitation electric field evaporation, whereby the atoms constituting the processed part are formed. Can be released at the atomic level from the workpiece and processed in the depth direction of the sample having a multilayer structure with nanometer order accuracy.

  This method will be further described. Under an ultra-high vacuum, when an electric field due to a high electric field is applied to the processed part of the sample and laser light is applied to provide photoexcitation energy, the atoms constituting the processed part are subjected to the processed part. Can give energy to jump out from. That is, photoexcitation electric field evaporation can be performed. At this time, the energy by the high electric field and the laser beam is applied at the atomic level, and thus does not affect the atomic structure of the unapplied portion. Further, since this photo-excited electric field evaporation is induced by laser light in addition to the action of a high electric field, it can also be performed on an insulating sample and can be processed. Furthermore, this photo-excited field evaporation can suppress the electric field strength to a lower level than the case where atoms are evaporated by a high electric field alone. As a result, for example, even when a high electric field is formed with a needle-like electrode, the atoms that have moved as the processing is repeated accumulate on the tip of the needle-like electrode, making it impossible to maintain the desired electric field strength or distribution. You can prevent.

  According to a second aspect of the present invention, in the first aspect of the present invention, an electrode provided with a pinhole is disposed opposite to a region including the processed portion of the sample, and a voltage is applied between the electrode and the sample. In addition to forming a high electric field, the laser beam is irradiated through the pinhole, the optical path of the pinhole and the laser beam is aligned, and the sample is processed while moving both relative to the sample. A fine processing method is provided.

  According to the above invention, the electrode provided with the pinhole is disposed opposite to the region including the processed part of the sample, and a high electric field is formed by applying a voltage between the electrode and the sample. The laser beam is irradiated through the pinhole, the optical path of the pinhole and the laser beam is aligned, and the processing is performed while moving both relative to the sample. It is easy to control the range, and processing can be performed with high positional accuracy in the plane direction of the sample. Further, since the laser beam is irradiated through the pinhole, even if atoms emitted from the processed portion of the sample adhere to the electrode, it is possible to prevent a laser output decrease due to the atom attachment.

  According to a third aspect of the present invention, in the second aspect of the present invention, the sample deposited on the electrode by applying a voltage in the opposite direction between the portion of the sample that is not the processed portion and the electrode in the process of processing. A microfabrication method of a sample for removing atoms is provided.

  According to the above invention, even if atoms emitted from the processed portion of the sample adhere to the electrode, the attached atoms are removed by applying a reverse voltage at a portion that is not the processed portion, thereby obtaining a desired electric field. Strength or distribution can be maintained. Thereby, it is possible to stably process a wider range for a long time.

  According to a fourth aspect of the present invention, in the second aspect, a conductive dummy plate is provided in addition to the sample, and a voltage in a direction opposite to the above is applied between the dummy plate and the electrode in the process of processing. A sample microfabrication method for removing sample atoms deposited on the substrate is provided.

  According to the above invention, even if atoms emitted from the processed part of the sample adhere to the electrode, the attached atoms are removed by applying a reverse voltage with the conductive dummy plate to obtain a desired electric field strength or Distribution can be maintained. Thereby, it is possible to stably process a wider range for a long time.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, a high electric field is formed between the sample and the electrode, and a laser beam is irradiated to a processed portion of the sample to perform photoexcitation electric field evaporation. The present invention provides a microfabrication method for a sample to be applied.

  According to the above invention, the portion to be processed of the sample is irradiated with pulsed laser light to cause photoexcitation electric field evaporation, so that stronger photoexcitation energy can be imparted. Thereby, even if a sample is insulating, it can be processed by performing photoexcitation electric field evaporation. Moreover, the electric field intensity for performing photoexcitation electric field evaporation can be suppressed low. As a result, for example, even when a high electric field is formed with a needle-like electrode, the atoms that have moved as the processing is repeated accumulate on the tip of the needle-like electrode, making it impossible to maintain the desired electric field strength or distribution. You can prevent.

  According to a sixth aspect of the present invention, in the fifth aspect, an optical element is introduced on the optical path of the pulse laser, and the fineness of the sample irradiated to the processing portion of the sample by manipulating the polarization characteristics and the polarization direction of the pulse laser. A processing method is provided.

  According to the above invention, for example, by manipulating the polarization direction of a linearly polarized pulse laser, the direction of the electric field electrically applied between the electrode and the sample is aligned with the polarization direction of the laser beam, thereby processing the laser beam. Efficiency can be increased. Further, by manipulating the polarization characteristics of the pulse laser, for example, linearly polarized light and circularly polarized light, it is possible to manipulate the processed part and processed shape of the sample.

  According to a seventh aspect of the present invention, in the fifth or sixth aspect, the electrode is made of a transparent material having no absorption near the wavelength of the pulse laser beam, and the pulse laser beam is transmitted through the electrode. A fine processing method of a sample to be irradiated is provided.

  According to the above invention, since the laser beam can be irradiated from the outside of the electrode through the electrode made of a transparent material, the degree of freedom is provided at the installation position of the laser beam irradiation means, and the position of the laser irradiation position is also improved. Control becomes easy.

  According to an eighth aspect of the present invention, in the seventh aspect of the present invention, a plurality of electrodes for applying a voltage to the sample are placed facing a plurality of processed surfaces of the sample, and the plurality of samples are fixed while the sample is fixed. A fine processing method of a sample to be processed on a processing surface is provided.

  According to the above invention, by changing the electrode to which the voltage is applied and operating the position of the laser irradiation source, a plurality of different sample surfaces can be processed while the sample is fixed.

  According to a ninth aspect of the present invention, in any one of the fifth to eighth aspects of the present invention, there is provided a microfabrication method of a sample that scans the irradiation position of the pulsed laser beam and processes it into a predetermined pattern.

  According to the above invention, since the processing is performed by scanning the irradiation position of the pulse laser beam, it can be processed with high positional accuracy in the plane direction of the sample. As a result, the cleaning of the sample surface and the formation of a fine pattern can be performed with accuracy on the order of nanometers in the depth direction of the sample, and can be performed with accuracy on the order of micrometers in the direction of surface formation of the sample. .

  According to a tenth aspect of the present invention, in any one of the fifth to ninth aspects of the present invention, there is provided a microfabrication method for a sample that is irradiated with pulsed laser light through an optical fiber.

  According to the above invention, since the pulse laser beam is irradiated through the optical fiber, the position of the laser irradiation source can be easily operated, and it becomes easier to process a plurality of different sample surfaces while fixing the sample.

  An eleventh aspect of the present invention provides the sample microfabrication method according to the tenth aspect, wherein an electrode coated on the optical fiber is used to form a high electric field between the sample and the electrode.

  According to the invention, the electrode coated on the optical fiber is used to form a high electric field between the sample and the electrode. Therefore, the electric field range and the irradiation position of the pulsed laser beam can be easily aligned, and photoexcitation electric field evaporation is performed. It becomes easy to control the position and range, and processing can be performed with high positional accuracy in the plane direction of the sample.

  According to a twelfth aspect of the present invention, in the tenth or eleventh aspect of the present invention, there is provided a sample microfabrication method in which a plurality of optical fibers are used to simultaneously process a plurality of locations.

  According to the above invention, a plurality of locations on the sample can be processed simultaneously.

  A thirteenth aspect of the present invention is the process according to any one of the first to twelfth aspects, wherein the workpiece is processed by the processing laser or another laser irradiated coaxially with the processing laser while processing the sample. A microfabrication method of a sample for measuring a Raman spectrum is provided.

  According to the above invention, the sample can be analyzed and evaluated by Raman scattering spectrum measurement while revealing a fresh analysis surface of the sample.

  In a fourteenth aspect of the present invention, in any one of the first to thirteenth aspects, a high voltage pulse is applied between the processed portion of the sample and the electrode to form a high electric field, and at the same time, It is intended to provide a fine processing method of a sample that irradiates a laser beam and performs photoexcitation electric field evaporation.

  According to the above invention, a high voltage pulse is applied between the processed part of the sample and the electrode to form a high electric field, and at the same time, the processed part is irradiated with laser light to cause photoexcitation electric field evaporation. As a result, the atoms constituting the workpiece can be released from the workpiece at an atomic level and processed in the depth direction of the sample having the multilayer structure with nanometer order accuracy.

  According to a fifteenth aspect of the present invention, in the fourteenth aspect of the present invention, there is provided a fine processing method of a sample to be irradiated by changing the beam diameter of the laser beam in accordance with the size and the processing speed of a processed part.

  According to the said invention, it becomes easy to adjust the size and processing speed of a to-be-processed part.

  According to a sixteenth aspect of the present invention, in the fourteenth or fifteenth aspect of the present invention, there is provided a microfabrication method for a sample in which the electrode has a flat or needle shape.

  According to the above invention, when the electrode has a flat plate shape, a high electric field is formed over a relatively wide range corresponding to the flat plate electrode. Processing at an arbitrary position on the sample surface can be performed by sequentially moving the position. In addition, when the electrode has a needle shape, a strong high electric field is formed in a relatively narrow range corresponding to the needle shape electrode, so that a high voltage pulse can be applied efficiently.

  According to a seventeenth aspect of the present invention, in the first aspect of the present invention, a plurality of needle-like electrodes are arranged facing a region including the processed portion of the sample, and laser light is applied to the processed portion of the sample. In addition, a high electric field is formed between the needle-shaped electrode and the sample, and photo-excited electric field evaporation is performed to process the processed portion of the sample into an uneven shape, and then a high voltage is applied to the sample. Thus, the present invention provides a microfabrication method for a sample in which electric field evaporation is performed on the convex portion of the sample processed into a concavo-convex shape.

  According to the above invention, after the processed portion of the sample is processed into a concavo-convex shape by performing photoexcitation electric field evaporation, a high voltage is applied to the sample, and the atoms constituting the convex portion are formed in the formed convex portion. By evaporating the electric field, the convex portion can be removed and flattened, and the sample surface can be thinned.

  According to an eighteenth aspect of the present invention, in the first aspect of the present invention, a plurality of needle-like electrodes are arranged facing a region including the processed portion of the sample, and laser light is applied to the processed portion of the sample. In addition, a high electric field is formed between the needle-shaped electrode and the sample, and photo-excited electric field evaporation is performed to process the processed portion of the sample into an uneven shape, and then a high voltage is applied to the sample. In addition, the present invention provides a sample microfabrication method that irradiates a laser beam to cause photo-excitation electric field evaporation to occur on a convex portion of a sample processed into a concavo-convex shape.

  According to the above-described invention, the processed portion of the sample is processed into a concavo-convex shape by performing photoexcitation electric field evaporation, and a high voltage is applied to the sample, and the processed portion is irradiated with laser light. By performing photoexcitation electric field evaporation of the atoms constituting the convex portion in the convex portion, the convex portion can be removed and flattened, and the sample surface can be made thin. Moreover, since photoexcitation electric field evaporation induced by laser light is performed, the surface of the sample can be thinned regardless of whether the sample is conductive or insulating.

  According to a nineteenth aspect of the present invention, in the seventeenth or eighteenth aspect of the present invention, after processing the processed portion of the sample into a concavo-convex shape, the needle-like electrode is arranged so as to face the side surface of the convex portion of the processed portion, The present invention provides a microfabrication method for a sample in which a high electric field is formed between the sample and the electrode, and electric field evaporation is performed on the side surface of the convex portion.

  According to the above-described invention, after the processed portion of the sample is processed to be uneven by performing photoexcitation electric field evaporation, the high electric field is directed to the side surface of the formed convex portion, and the atoms constituting the side surface of the convex portion Is evaporated from the electric field, the volume of the convex portion can be reduced from the side surface, and the convex portion can be easily removed and flattened.

  According to a twentieth aspect of the present invention, in the seventeenth or eighteenth aspect of the present invention, after processing the processed portion of the sample into a concavo-convex shape, the needle-like electrode is arranged so as to face the side surface of the convex portion of the processed portion, Provided is a sample microfabrication method for forming a high electric field between the sample and the electrode and irradiating the side surface of the convex portion with a laser beam to perform photoexcitation electric field evaporation on the side surface of the convex portion. To do.

  According to the above-described invention, the processed portion of the sample is processed to be uneven by performing photoexcitation electric field evaporation, and then a high electric field and laser light are directed to the side surface of the formed convex portion, and the side surface of the convex portion As a result of the photoexcitation electric field evaporation, the volume of the convex portion can be reduced from the side surface, and the convex portion can be easily removed and flattened. Moreover, since photoexcitation electric field evaporation induced by laser light is performed, the surface of the sample can be thinned regardless of whether the sample is conductive or insulating.

  According to the present invention, a high electric field is formed on a processed portion of a sample having a multilayer film structure, and laser excitation is performed to cause photoexcitation electric field evaporation. Thus, atoms constituting the processed portion are formed. Can be released at the atomic level from the workpiece and processed in the depth direction of the sample having a multilayer structure with nanometer order accuracy. At this time, the energy by the high electric field and the laser beam is applied at the atomic level, and thus does not affect the atomic structure of the unapplied portion. Further, since this photo-excited electric field evaporation is induced by laser light in addition to the action of a high electric field, it can also be performed on an insulating sample and can be processed. Furthermore, this photo-excited field evaporation can suppress the electric field strength to a lower level than the case where atoms are evaporated by a high electric field alone. As a result, for example, even when a high electric field is formed with a needle-like electrode, the atoms that have moved as the processing is repeated accumulate on the tip of the needle-like electrode, making it impossible to maintain the desired electric field strength or distribution. You can prevent.

It is explanatory drawing explaining the method of etching from the surface to a perpendicular direction by irradiating an ion beam as a prior art. It is explanatory drawing explaining the grinding | polishing method which grinds to an inclined surface using an abrasive grain as a prior art. It is explanatory drawing explaining the method of processing a surface using the fact that an atom is sucked out by the electric field applied to the surface as a prior art. It is a figure which shows the 1st of embodiment of this invention, The electrode which makes the needle shape provided with the pinhole is arrange | positioned, (a) is the state by which the atom of a sample surface is discharge | released to the electrode side by photoexcitation electric field evaporation. Explanatory drawing, (b) is explanatory drawing of the state which removes the sample atom deposited on the electrode. It is a figure which shows the 2nd of embodiment of this invention, and the thing which provided the several pinhole in the electrode which makes a flat form is arrange | positioned, (a) is discharge | released the atom of a sample surface to the electrode side by photoexcitation electric field evaporation (B) is an explanatory view of a state in which sample atoms deposited on the electrode are removed. It is a figure which shows 3rd of embodiment of this invention, and is a layout drawing of the electrode installed in multiple numbers facing the some to-be-processed surface of a sample. It is a figure which shows the 3rd of embodiment of this invention, and the electrode for applying a voltage to a sample is installed with two or more facing the some to-be-processed surface of a sample, (a) is one sample surface photoexcited. Explanatory drawing of the state before the process processed by electric field evaporation, (b) is an explanatory view of the state after the process of (a), (c) is the state before the process by which another sample surface is processed by photoexcitation electric field evaporation (D) is explanatory drawing of the state after the process of (c). It is a figure which shows the other state of the 3rd Embodiment, and is explanatory drawing of the state which has arrange | positioned the electrode so that the whole sample may be enclosed. It is a figure which shows 4th of embodiment of this invention, In the state which scans the irradiation position of a pulse laser beam and processes it into a predetermined pattern, (a) is explanatory drawing of the state before a process, (b) is after a process It is explanatory drawing of the state of. It is a figure which shows 5th Embodiment of this invention, (a) is explanatory drawing of the state before a process in the state which processes a sample by photoexcitation electric field evaporation using the electrode coated by the optical fiber, (b) These are explanatory drawings of the state after processing. It is a figure which shows 6th of embodiment of this invention, and is explanatory drawing of the state which processes a sample by photoexcitation electric field evaporation using the electrode which makes flat form. It is a figure which shows the 7th of embodiment of this invention, and is explanatory drawing of the state which processes a sample by photoexcitation electric field evaporation using the electrode which makes a needle shape. It is a figure which shows the 8th of embodiment of this invention, opposes the area | region containing the to-be-processed part of a sample, arrange | positions the acicular electrode which consists of a plurality of things, and applies a laser beam to the to-be-processed part of a sample. It is explanatory drawing of the state which irradiates and processes a to-be-processed part by uneven | corrugated shape by light excitation electric field evaporation. In the eighth embodiment, the processed portion of the sample is processed into a concavo-convex shape along the shape of a plurality of needle-shaped electrodes (a) Before and after (b) processing It is. In the 8th Embodiment, it is explanatory drawing of the state which is applying the high electrolysis to the sample processed into the uneven | corrugated shape, and electric field evaporation generate | occur | produces in a convex part. In the 8th Embodiment, it is explanatory drawing of the state of the sample after processing.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. Although the description thereof is omitted in the following embodiments, the present invention is performed in a processing chamber equipped with a decompression means such as a rotary pump, a scroll pump, a turbo molecular pump, an ion pump, and the order of 10 ⁻⁸ Pa or less. It is necessary to carry out under ultra high vacuum. In addition, the “high electric field” in the present invention means a high electric field that can be processed in combination with laser light, and it depends on the processing object and the characteristics of the laser light used, but it is about several V / nm. Means a high electric field.

  First, a first embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, as shown in FIG. 4A, a sample in which five layers of thin films 102 to 106 are formed on a silicon substrate 101 is used as a sample having a multilayer structure. Specific examples of the sample having a multilayer structure include a thin film solar cell and a semiconductor element.

  In FIG. 4A, the sample surface of the sample having the multilayer film structure is formed by the thin film 106, and this is the processed portion of the sample. Then, a needle-like electrode 11a provided with a pinhole 12 is arranged opposite to the region including the processed portion, and a high electric field is formed by applying a voltage between the electrode 11a and the sample. It is supposed to be. Further, the laser beam 13 is irradiated through the pinhole 12. By aligning the optical path of the pinhole 12 (electrode 11a) and the laser beam 13 and moving both relative to the sample, a high electric field is formed at an arbitrary position of the processed portion of the sample, Laser light can be irradiated, and the above-described photoexcitation electric field evaporation can be performed. That is, when a voltage is applied and the electrode side is negatively charged and the sample side is charged positively, an electric field is formed between the electrode samples, and atoms constituting the thin film 106 on the sample surface are released to the electrode side by photoexcitation electric field evaporation. Processing can be performed. At this time, the processing depth can be changed by the voltage value, the laser irradiation time, or the voltage application time. Therefore, while changing the voltage or changing the laser moving speed, the optical path of the pinhole 12 (electrode 11a) and the laser beam 13 is aligned, and both of them are moved relative to the sample, so that clean and damaged It is possible to expose an analysis surface having no shape in an arbitrary shape. Since the pinhole 12 can also serve as a means for narrowing the laser beam, it can be used to contribute to adjusting the intensity and distribution of the laser irradiation of the sample to be processed. Separately, a lens may be provided before or after passing through the pinhole 12 on the path of the laser light to adjust the beam diameter of the laser light.

  FIG. 4B shows an embodiment in the case where the sample atoms deposited on the electrodes are removed in the first embodiment. For example, when a needle-like electrode is used, as shown in FIG. 4A, atoms that have moved during repeated processing are deposited on the tip of the needle-like probe, and the desired electric field strength or Distribution may not be maintained. In such a case, a sample atom deposited on the electrode can be removed by applying a voltage in the opposite direction to the above in the course of processing. That is, when the electrode 11a is moved to a non-processed surface other than the sample surface and then the electrode side is charged positively and the sample side is negatively charged, an electric field opposite to that when processing the sample is formed between the electrode samples. Is done. Thereby, atoms attached to the surface of the electrode 11a move to the sample side. In this case, if the laser beam 13a is glazed from a laser irradiation means (not shown) and the electrode is widely irradiated, atoms attached to the surface of the electrode 11a can be moved more efficiently to the sample side by photoexcitation electric field evaporation. it can. In this case, as shown in FIG. 4B, a conductive dummy plate 14 is provided in addition to the sample, and a voltage in the opposite direction to that during processing is applied between the dummy plate and the electrode during the processing, You may make it remove the sample atom deposited on the electrode. As described above, by removing and cleaning the sample atoms deposited on the electrodes, it is possible to stably process a wider range for a long time.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the second embodiment, the electrode 11b having a flat plate shape as the seven electrodes is provided with a plurality of pinholes 12. Then, a plurality of laser beams are irradiated to the processed portion of the sample through the plurality of pinholes 12 provided. In addition, a high electric field can be distributed along the shape of the electrode 11b having a flat plate shape. In addition, by irradiating a plurality of laser beams simultaneously, photoexcitation electric field evaporation can be performed over a wide range of the sample surface. . By such an aspect, it is possible to process over a wide range of the sample surface at a time. If necessary, as shown in FIG. 5B, the sample atoms deposited on the electrode can be removed and cleaned in the same manner as the embodiment described in FIG. 4B.

  Next, a third embodiment of the present invention will be described with reference to FIGS.

  In the third embodiment, as shown in FIG. 6, a rectangular parallelepiped sample 21 is set in a processing chamber (not shown) adjusted to a high vacuum. Further, in the processing chamber, a plate-like electrode 22 is arranged to face one side surface of the sample, and a plate-like electrode 23 is arranged to face the other side surface. Although there is no limitation on the shape of the sample, it is preferably a single layer or laminated thin film sample that has been processed to a size of the order of μm in advance.

  As shown in FIG. 7A, a voltage is applied between the electrode 22 and the sample 21 to form a high electric field E between the opposing surfaces of the sample 21. In this state, as shown in FIG. 7 (b), the laser beam irradiation means (not shown) irradiates the processed portion 22a with pulsed laser light to perform photoexcitation electric field evaporation, and emit atoms from that portion. Thus, the sample surface can be processed into a concave shape.

  Further, as shown in FIG. 7C, a voltage is applied between the electrode 23 and the sample 21 to form a high electric field E between the opposing surfaces of the sample 21. In this state, the surface of the sample is processed into a concave shape by irradiating the laser beam irradiation means to the processing portion 23a with a laser beam irradiation means (not shown) to cause photoexcitation electric field evaporation and releasing atoms from the portion. be able to.

  In this way, by changing the electrode to which the voltage is applied from the electrode 22 to the electrode 23, it is possible to process a plurality of processed surfaces of the sample while the sample 21 is fixed. At this time, it goes without saying that the position of the irradiation source of the pulse laser beam can be arbitrarily changed by operating the position of the laser irradiation source by a laser beam irradiation means (not shown) or by using another laser irradiation source (not shown). Moreover, when applying a voltage, it is preferable that a voltage is applied only to a sample and one of the electrodes, and all electrodes to which no voltage is applied are grounded. Thereby, the change of the electrode which applies a voltage can be performed reliably.

  As the type of pulsed laser light to be used, one having a nanosecond, picosecond, or femtosecond pulse width can be appropriately selected according to the characteristics of the sample and the applied high electric field. Further, an optical element or a polarizing plate may be introduced on the optical path of the pulse laser, and the processed portion of the sample may be irradiated by manipulating the polarization characteristics and the polarization direction of the pulse laser. According to this, for example, by manipulating the polarization direction of a linearly polarized pulse laser, the direction of the electric field electrically applied between the electrode and the sample is aligned with the polarization direction of the laser beam, thereby processing efficiency. Can be increased. Further, by manipulating the polarization characteristics of the pulse laser, for example, linearly polarized light and circularly polarized light, it is possible to manipulate the processed part and processed shape of the sample.

  Further, as shown in FIG. 8, the electrode 24 may be disposed so as to surround the entire sample 21. In this case, the optical path of the laser beam is blocked by the electrode, and it is difficult to process the target portion. Therefore, it is preferable that the electrode 24 is made of a transparent material that does not absorb near the wavelength of the pulse laser beam, and the pulse laser beam is irradiated through the electrode. According to this, it is possible to process a portion that is behind the electrode when viewed from the optical path of the laser beam. Examples of transparent materials that do not absorb near the wavelength of pulsed laser light include ITO (indium tin oxide; tin-doped indium oxide) and organic polymer materials.

  Next, a fourth embodiment of the present invention will be described with reference to FIG.

  In the fourth embodiment, the irradiation position of the pulse laser beam is scanned and processed into a predetermined pattern. That is, the optical fiber 26 serves as a laser beam irradiation means, and is installed so as to be able to scan the sample 25 surrounded by the electrode 27 having a flat plate shape. The position of the optical fiber 26 can be precisely controlled, for example, by attaching an xyz stage with a piezo element attached to a holder that holds the optical fiber, forming a high electric field between the sample and the electrode 27, By irradiating pulsed laser light from the optical fiber 26 to perform photoexcitation electric field evaporation, the sample surface can be cleaned and a fine pattern can be formed with a precision of nanometer order in the depth direction of the sample. It becomes possible to carry out with accuracy of micrometer order in the surface formation direction. As described above, it is needless to say that the position of the irradiation source of the pulse laser beam can be arbitrarily changed by operating the position of the laser irradiation source by the optical fiber 26 or using another laser irradiation source (not shown). In this case, since the pulse laser beam is irradiated through the optical fiber 26, the position of the laser irradiation source can be easily operated. Further, as the material of the electrode 27, not only a metal but also ITO (indium tin oxide; tin-doped indium oxide), an organic polymer material, or the like is used as a transparent material that does not absorb near the wavelength of the pulse laser beam. Can do.

  Further, a plurality of optical fibers corresponding to the optical fiber 26 can be used to simultaneously process a plurality of locations.

  FIG. 9 shows an example in which the corner of the sample is processed into a concave shape. In this case, as described above, an optical element or a polarizing plate is introduced on the optical path of the pulse laser, so that the polarization of the pulse laser is changed. By manipulating the characteristics and the polarization direction, for example, by adjusting the angle and position of the optical fiber 26 so that the polarization direction of the linearly polarized pulse laser is orthogonal to the electrode facing the processing surface, Since the edge shape is spherical, the corner portion of the sample is easy to be inclined.

  Next, a fifth embodiment of the present invention will be described with reference to FIG.

  In the fifth embodiment, an electrode 29 coated on the optical fiber 28 is used to form a high electric field between the sample and the electrode. That is, the optical fiber 28 coated with the electrode 29 is installed so as to be able to scan the sample 25 and serves as a laser beam irradiation means and also serves as an electrode. The electrode 29 is made of a conductive material that can be coated. For example, an organic conductive polymer film, a metal vapor deposition film, etc. can be illustrated. The position of the optical fiber 28 coated with the electrode 29 can be precisely controlled, for example, by attaching an xyz stage with a piezo element attached to a holder that holds the optical fiber, and between the sample and the electrode 29. By forming a high electric field and irradiating pulsed laser light from the optical fiber 28 to perform photo-excited electric field evaporation, the sample surface is cleaned and a fine pattern is formed with a precision of nanometer order in the depth direction of the sample. In addition, it is possible to carry out with accuracy of micrometer order in the surface formation direction of the sample. As described above, it is needless to say that the position of the irradiation source of the pulse laser beam can be arbitrarily changed by operating the position of the laser irradiation source by the optical fiber 28 or using another laser irradiation source (not shown). In this case, since the pulse laser beam is irradiated through the optical fiber, the position of the laser irradiation source can be easily operated. As the material of the electrode 29, not only a metal but also ITO (indium tin oxide; tin-doped indium oxide) or an organic polymer material is used as a transparent material having no absorption near the wavelength of the pulsed laser beam. Can do.

  Further, a plurality of optical fibers corresponding to the optical fiber 28 coated with the electrode 29 can be used to simultaneously process a plurality of locations.

  FIG. 10 shows an example in which the corner portion of the sample is obliquely processed. In this case, as described above, an optical element or a polarizing plate is introduced on the optical path of the pulse laser, and the polarization characteristics of the pulse laser are shown. And by manipulating the polarization direction and adjusting the angle and position of the optical fiber 28 so that the circularly polarized light is incident, for example, the edge shape of the portion excavated by processing becomes planar, so the corner portion of the sample is inclined. Easy to process.

  Next, a sixth embodiment of the present invention will be described with reference to FIG.

  In the sixth embodiment, as shown in FIG. 11, a thin plate-shaped sample 31 is set in a processing chamber (not shown) adjusted to an ultrahigh vacuum. In the processing chamber, an electrode 32a having a flat plate shape is disposed to face one side surface of the sample. Further, a high voltage pulse power source 33 for applying a voltage between the sample 31 and the electrode 32a is disposed and connected between the sample 31 and the electrode 32a. FIG. 11A shows a state seen from the side surface, and FIG. 11B shows a state seen from the upper surface.

  Here, the high voltage pulse power source 33 applies a negative high voltage pulse to the electrode 32a so that the sample 31 does not evaporate in the electric field. Simultaneously with the application of the high voltage pulse, the sample surface is irradiated with laser light 34 from a laser light irradiation means (not shown). Then, only the sample surface 35 irradiated with the laser reaches the evaporation electric field by the photoelectric field of the laser beam, and the sample surface is processed by electric field evaporation. Thereafter, it is possible to process an arbitrary position on the sample surface by sequentially moving the irradiation position of the laser beam. FIG. 11C shows the shape of the processed part as viewed from above.

  The laser beam 34 may be irradiated while changing its beam diameter. Thereby, it becomes easy to adjust the size and processing speed of a to-be-processed part.

  Next, a seventh embodiment of the present invention will be described with reference to FIG.

  In the seventh embodiment, as shown in FIG. 12, a thin plate-shaped sample 31 is set in a processing chamber (not shown) adjusted to an ultrahigh vacuum. In the processing chamber, an electrode 32b having a needle shape is disposed opposite to one side surface of the sample. In addition, a high voltage pulse power source 33 that applies a voltage between the sample 31 and the electrode 32b is disposed and connected between the sample 31 and the electrode 32b. FIG. 12A is a state seen from the side surface, and FIG. 12B is a state seen from the upper surface.

  Here, the high voltage pulse power source 33 applies a negative high voltage pulse to the electrode 32b so that the sample 31 does not evaporate in the electric field. Simultaneously with the application of the high voltage pulse, the sample surface is irradiated with laser light 34 from a laser light irradiation means (not shown). Then, only the sample surface 35 irradiated with the laser reaches the evaporation electric field by the photoelectric field of the laser beam, and the sample surface is processed by electric field evaporation. Thereafter, it is possible to perform processing at an arbitrary position on the sample surface by sequentially moving the needle-like electrode 32b and the irradiation position of the laser light in synchronization. FIG. 12C shows a state where the shape of the processed portion is viewed from above.

  The laser beam 34 may be irradiated while changing its beam diameter. Thereby, it becomes easy to adjust the size and processing speed of a to-be-processed part.

  As described in the sixth or seventh embodiment, in the present invention, a method for processing a surface using electric field evaporation itself by application of a voltage, such as a processing method using a conventional STM probe, is used. In contrast, atoms are emitted from the workpiece by being induced by a photoelectric field of laser light. Therefore, processing can be performed at the atomic level without damaging the sample regardless of whether it is a conductive or insulating sample. In addition, workability is less likely to deteriorate due to changes in electrode shape.

  Next, an eighth embodiment of the present invention will be described with reference to FIGS.

  In the eighth embodiment, as shown in FIG. 13, a thin plate-like sample 41 is set in a processing chamber (not shown) adjusted to an ultra-high vacuum. A plurality of needle-like electrodes 45 are arranged opposite to each other. Further, a laser beam 43 is radiated from an optical fiber 42 serving as a laser beam irradiating means to a region including a portion to be processed of the sample 41.

  FIG. 14A shows a state before processing in which no voltage is applied to the electrode 45. Further, FIG. 14B shows a state after processing with voltage applied. In these figures, the electrode 45 is disposed in proximity to both surfaces of the thin plate-like sample 41 so that both surfaces can be processed. That is, when a voltage is applied to the electrode 45 in the state shown in FIG. 14A and a high electric field is formed between the opposing sample surfaces, the high electric field is distributed along the comb shape of the electrode 45. Therefore, when the laser beam 43 shown in FIG. 13 is further irradiated, the above-described photoexcitation electric field evaporation is performed, and atoms are emitted from the surface of the sample 41 along the comb shape of the electrode 45. it can. Thereby, the part from which the atom was emitted becomes concave, and the part from which the atom has not been emitted becomes convex. At this time, the electrode 45 may be moved up and down with respect to the sample direction in order to form this shape uniformly in the processed portion of the sample. Moreover, you may change the voltage applied for every acicular electrode of the electrode 45. FIG. By repeating this operation in the plane direction of the sample, the processed portion of the sample can be processed into an uneven shape.

  Next, as shown in FIG. 15, a high voltage pulse power source 46 is connected to the sample 41a processed into a concavo-convex shape, and a high voltage pulse 46a of about several V / nm is applied to the sample. Thereby, in the convex part of the sample processed into the uneven shape, atoms of the convex part are ionized and discharged from the sample 1 by electric field evaporation. As a result, as shown in FIG. 16, a sample 41b having a flat surface is obtained. In this way, the sample can be thinned.

  In another aspect of the eighth embodiment, the sample 41a (FIG. 15) processed into a concavo-convex shape is applied with the high-voltage pulse and irradiated with laser light to be processed into a concavo-convex shape. It is also possible to cause photoexcitation electric field evaporation to be performed on the protrusions. In this case, in the convex part of the sample processed into a concavo-convex shape, the atoms of the convex part are ionized and emitted from the sample 41a by photoexcitation electric field evaporation. Thereby, the convex part can be removed and flattened, and the sample surface can be thinned. Moreover, since photoexcitation electric field evaporation induced by laser light is performed, the surface of the sample can be thinned regardless of whether the sample is conductive or insulating.

  In still another aspect of the eighth embodiment, the needle-like electrode is arranged so as to face the side surface of the convex portion of the sample 41a (FIG. 15) processed into a concavo-convex shape, and between the sample and the electrode. It is also possible to form a high electric field and cause electric field evaporation to be performed on the side surface of the convex portion. According to this, the volume of the convex portion can be reduced from the side surface, and it becomes easy to remove the convex portion and flatten it. Further, the needle-like electrode is arranged so as to be directed to the side surface of the convex portion of the sample 41a (FIG. 15) processed into a concavo-convex shape, and a high electric field is formed between the sample and the electrode and laser light is irradiated. Thus, photoexcitation electric field evaporation can be performed on the side surface of the convex portion. According to this, photoexcitation electric field evaporation induced by laser light is performed, so that the surface of the sample can be thinned regardless of the conductive / insulating sample.

  If the sample is thinned by the method as described above, it is easier to form a clean thin film surface than the method using other elements that cause contamination or the method using physical means. Become. In addition, the cleaning of the sample surface and the formation of a fine pattern can be performed with accuracy on the order of nanometers in the depth direction of the sample, and can be performed with accuracy on the order of micrometers on the surface formation direction of the sample.

On the other hand, in another aspect of the present invention, the Raman spectrum of the part to be processed may be measured by a processing laser or another laser irradiated coaxially with the processing laser while processing the sample. Good. Laser light for this purpose includes pulse lasers with nanosecond, picosecond, or femtosecond pulse widths for the above processing, as well as cw lasers in the ultraviolet to near infrared region, such as He-Ne lasers and Ar ⁺ lasers. Etc. can be used. A known system may be used as an optical measurement system arranged for observing the scattered light. According to this, analysis evaluation of a sample can be performed by Raman scattering spectrum measurement while revealing a fresh analysis surface of the sample.

11a, 11b, electrode 12 pinhole 13, 13a laser beam 14 conductive dummy plate 21, 25 sample 22, 23, 24, 27, 29 electrode 22a, 23a processed part 26 optical fiber 28 optical fiber 31 coated with electrode sample 32a , 32b electrode 33 high voltage pulse power supply 34 laser light 35 sample surface 41, 41a, 41b irradiated with laser beam 42 optical fiber 43 laser light 45 electrode 46 high voltage pulse power supply 46a high voltage pulse 101 silicon substrate 102-106 thin film 107 ion Beam 108 Polishing surface 109 Sample surface 112 before polishing Needle-shaped probe 113 Atom E constituting sample surface High electric field

Claims (20)

  In a method of finely processing a sample having a multilayer film structure without damaging its atomic structure, a high electric field is formed on the processed portion of the sample and the laser beam is irradiated under an ultrahigh vacuum. Then, a microfabrication method for a sample, characterized in that photoexcitation electric field evaporation is performed.   An electrode provided with a pinhole is arranged opposite to the region including the processed part of the sample, and a high electric field is formed by applying a voltage between the electrode and the sample, and a laser is passed through the pinhole. The sample microfabrication method according to claim 1, wherein processing is performed while irradiating light, aligning optical paths of the pinhole and laser light, and moving both relative to the sample.   3. The microfabrication method for a sample according to claim 2, wherein a voltage in a direction opposite to the above is applied between a portion of the sample that is not a part to be processed and the electrode in the course of the processing to remove sample atoms deposited on the electrode. .   The sample according to claim 2, wherein a conductive dummy plate is provided in addition to the sample, and a voltage in a direction opposite to the above is applied between the dummy plate and the electrode to remove sample atoms deposited on the electrode during the processing. Fine processing method.   The microfabrication method for a sample according to any one of claims 1 to 4, wherein a high electric field is formed between the sample and the electrode, and a laser beam is applied to the processing portion of the sample to perform photoexcitation electric field evaporation.   The sample microfabrication method according to claim 5, wherein an optical element is introduced on an optical path of the pulse laser, and the workpiece is irradiated by manipulating the polarization characteristics and the polarization direction of the pulse laser.   The sample microfabrication method according to claim 5 or 6, wherein the electrode is made of a transparent material having no absorption near the wavelength of the pulsed laser beam, and the pulsed laser beam is irradiated through the electrode.   The sample according to claim 7, wherein a plurality of electrodes for applying a voltage to the sample are disposed opposite to the plurality of processing surfaces of the sample, and the sample is processed with respect to the plurality of processing surfaces while the sample is fixed. Fine processing method.   The microfabrication method for a sample according to any one of claims 5 to 8, wherein the irradiation position of the pulse laser beam is scanned and processed into a predetermined pattern.   The microfabrication method for a sample according to any one of claims 5 to 9, wherein pulsed laser light is irradiated through an optical fiber.   The microfabrication method for a sample according to claim 10, wherein a high electric field is formed between the sample and the electrode using an electrode coated on the optical fiber.   The sample microfabrication method according to claim 10 or 11, wherein a plurality of optical fibers are used to simultaneously process a plurality of locations.   The sample according to any one of claims 1 to 12, wherein a Raman spectrum of a workpiece is measured by a processing laser or another laser irradiated coaxially with the processing laser while processing the sample. Fine processing method.   14. The method according to claim 1, wherein a high voltage pulse is applied between the processed portion of the sample and the electrode to form a high electric field, and at the same time, the processed portion is irradiated with laser light to perform photoexcitation electric field evaporation. The microfabrication method of the sample as described in any one.   The sample microfabrication method according to claim 14, wherein irradiation is performed by changing a beam diameter of the laser beam in accordance with a size and a processing speed of a workpiece.   The sample microfabrication method according to claim 14 or 15, wherein the electrode has a flat plate shape or a needle shape.   A plurality of needle-shaped electrodes are arranged facing the region including the processed portion of the sample, and the processed portion of the sample is irradiated with laser light, and the needle-shaped electrode and the sample are After forming a high electric field between them and performing photo-excited electric field evaporation to process the processed part of the sample into a concavo-convex shape, a high voltage is applied to the sample to The microfabrication method for a sample according to claim 1, wherein field evaporation is performed.   A plurality of needle-shaped electrodes are arranged facing the region including the processed portion of the sample, and the processed portion of the sample is irradiated with laser light, and the needle-shaped electrode and the sample are After forming a high electric field between them and performing photoexcited electric field evaporation to process the processed part of the sample into an uneven shape, a high voltage is applied to the sample and laser light is irradiated to process the sample into an uneven shape. The microfabrication method for a sample according to claim 1, wherein photoexcited electric field evaporation is performed on the convex portion of the sample.   After processing the processed portion of the sample into a concavo-convex shape, the needle-like electrode is arranged to face the side surface of the convex portion of the processed portion, and a high electric field is formed between the sample and the electrode, The microfabrication method for a sample according to claim 17 or 18, wherein electric field evaporation is performed on a side surface of the convex portion.   After processing the processed portion of the sample into a concavo-convex shape, the needle-shaped electrode is arranged to face the side surface of the convex portion of the processed portion, and a high electric field is formed between the sample and the electrode, 19. The microfabrication method for a sample according to claim 17 or 18, wherein photoexcitation electric field evaporation is performed on a side surface of the convex portion by irradiating a side surface of the convex portion with laser light.