Method and apparatus for processing a minute portion of a specimen

Abstract: An image of a specimen which is to be processed is detected by a near-field optical scanning microscope. An image with extremely high resolution for identifying a minute portion of several tens nm is detected. The detected minute portion is processed by, for example, a tunnel current of a scanning tunneling microscope.

Description: The present invention relates to a minute portion processing method and apparatus and a minute portion analytical method and apparatus for performing various processes such as detecting, analyzing, or processing minute portions, wiring or circuit patterns, or foreign particles of a device or material which are several tens nm in diameter, or film-forming, or annealing. As a wiring or circuit pattern of a semiconductor integrated circuit (hereinafter called a LSI) reduces in size to 0.3 µm, 0.2 µm, and then 0.1 µm and is highly integrated, more minute detecting resolution, detection accuracy, correction size, and correction accuracy are required for inspection of defects in the mask pattern, mending or correction of defects, or for detection of defects in a wiring pattern of a LSI and correction of defects. The minimum defect size of a LSI of the 0.3 µm rule, for example, ranges from 0.1 to 0.05 µm, and detecting resolution and correction accuracy for defects in such size are required. In the case of the 0.1 µm rule, the minimum defect size is 0.03 µm, and correction accuracy and detecting resolution for 0.03 µm or less are required. Inspection of minute foreign particles at each stage of the production process of such minute LSI wiring patterns poses problems. Foreign particles mixed in the production process cause a reduction in the yield rate. Therefore, it is required to check wafers for foreign particles by sampling inspection and to analyze the composition of the foreign particles. For a process where many foreign particles are mixed, it is required to recheck the production equipment, materials, chemicals, and others to increase the yielding rate. The minimum size of foreign particles is required to be 0.1 to 0.08 µm for the 0.3 µm rule or 0.03 µm for the 0.1 µm rule in the same way as above. Since those foreign particles are detected on each wafer pattern, not only high resolution but also a high signal-to-noise ratio are required. As to analysis of foreign particles, to define the section of the production process and the cause (equipment, materials, chemicals, operators) where and whereby foreign particles are generated and mixed, a high sensitivity and resolution analysis of foreign particles is required. When foreign particles are particularly minute such as less than 0.1 µm as mentioned above, mean analytical information by a analyzing probe for larger than 0.1 µm contains background information, foreign particles cannot be analyzed independently, and it is extremely difficult to analyze the composition of foreign particles and define the occurrence cause. Therefore, an analyzing probe for 0.1 to 0.08 µm is required for LSIs of the 0.3 µm rule or an analyzing probe for 0.03 µm or less for LSIs of the 0.1 µm rule. The above description is only for LSIs. In the information file field such as magnetic disks, optical disks, magneto-optical disks, and bubble memories or in the fields of thin film transistors (TFT) and image sensors, minuteness and high integration are advanced increasingly, and high accuracy and resolution are required for inspection and correction of defects in patterns and production masks or for detection and analysis of foreign particles in the same way as with LSIs. The minimum rule of LSIs described above is 0.1 µm. When the LSI size decreases below 0.1 µm, the so-called quantum effect (the effect based on the quantum theory) starts to appear gradually and the property as an electron wave appears. As a result, the integration increases much the more. In semiconductor device elements with a wiring width narrower than the 0.1 µm rule, a quantum effect device or an electron wave interference device, wherein the quantum effect is not negated but positively used, is under research and development. This matter is described in detail, for example, in H. Sasaki, "Scattering Suppression and High Mobility Effect of Size-Quantized Electrons in Ultrafine Semiconductor Wire Structures", Japanese Journal of Applied Physics Vol. 19, No. 12, pp. L735 - L738. Devices using this quantum effect are, for example, a quantum ultrafine wire laser and an electron wave interference device. Many devices other than the above two devices have developed. It is important that these devices are operated on condition that they use the electronic quantum effect and the size of major parts such as wires under which the quantum effect can be effectively used should range from 20 nm to several nm. Therefore, it is definite that the wire width will be smaller than that of LSIs, which are developed at present, by one digit, and a technique for forming such wires stably and highly accurately is a necessary problem for next generation LSIs. Techniques for forming such minute patterns are electron beam lithography and X-ray lithography. Assuming that an electronic integrated circuit or optical integrated circuit of a such size is formed, detection or correction of defects in the pattern or mask or detection or analysis of foreign partioles generated during processing are necessary. For wires 20 nm in width (or the device structure), for example, the defect size is 6 nm and hence the detecting resolution, minimum correction size, correction accuracy, and analyzing probe size should be 6 nm or less. Furthermore, for a device structure of 5 nm, the above four values should be 2 nm or less. The pattern inspection, pattern correction, and inspection and analysis of foreign particles during processing, which are necessary for production of highly integrated devices, are described above. There are local detection, analysis, and correction techniques for several µm or less and detection, correction, and analysis techniques by a laser beam conventionally available. The method using an electron beam can focus the beam diameter to from 10 nm to several Å. However, the method requires an acceleration voltage of 1 kV or more or 5 kV or more to obtain a particularly fine probe, and poses various problems such as damage to devices, adhesion of foreign particles or contaminants to devices due to the atmosphere in the chamber, the electron beam with a large spot diameter being spread in a specimen in an area of several µm in diameter, and a reduction in the horizontal and vertical spatial resolution. As to detection, correction, and analysis by an ultrafine focused ion beam (FIB), as indicated in Yamaguchi et al., U.S. Patent No. 4,983,540, "Method of Manufacturing Devices Having Superlattice Structures", and the corresponding European Patent Application Publication No. 0 317 952, "Device Having Superlattice Structure, and Method of and Apparatus for Manufacturing the Same", an ion beam from a liquid-metal ion source such as gallium can be focused to a spot 30 to 60 nm in diameter using a reduction lens system comprising two static lenses. However, this method requires acceleration energy of 1 keV or more and an acceleration voltage of 20 to 50 kV, and is suited to processing by the sputtering phenomenon because ions collide with a specimen, though it causes damage to the peripheral equipment; that is, a problem that the ion beam processes the specimen surface when the position is detected is imposed. As to this matter, an attempt has been made to minimize the damage processing to a specimen by fetching and reading an image of scanning ion microscopy obtained by one scanning of a focused ion beam (FIB) into an image storage unit, resulting in only a reduction in the above tendency. The focusing limit is possibly about 30 nm due to the magnitude of chromatic aberration by the energy spread of the liquid-metal ion source and the magnitude of effective diameter of the ion source. It is difficult to obtain resolution for a size smaller than 30 nm. Detection techniques using light (a laser beam is included), which have been developed, are essential to detect device patterns or foreign particles. This is because the reflected light intensity, spectrum, absorption rate, and absorption spectrum of patterns or foreign particles are useful for detection as important information. It is difficult, however, to focus light to each time interval of the wave length. In the wave length zone (infrared 1 µm to infrared 0.3 µm) which is useful for the above detection, the spatial resolution limit ranges from 0.1 to 0.2 µm and it is difficult to detect devices 0.1 µm or less in diameter. As an analyzing means, light (a laser beam is included) is a useful means for composition analysis by measuring absorption spectrums of molecular vibration, chemical bond, functional groups, intramolecular or intraatomic electrons, or quasiparticles such as phonon excided plasmor. However, since the spatial resolution is only each time interval of the wave length in the same way as above, it is difficult to correctly analyze foreign particles less than 0.1 µm in diameter. Analytical methods for minute portions, which are known at present, are micro-Auger analysis, scanning ion microspectroscopy (SIMS), energy dispersion X-ray spectroscopy (EDX), and an analytical transmission electron microscope (AEM). The micro-Auger analysis focuses an electron beam extremely finely to irradiate it to a specimen. Since the analysis, however, requires a large current at a low acceleration for analysis, it is not suited to the present object requiring analysis of foreign particles less than 0.03 µm in diameter. In the SIMS, a probe of 0.05 µm to 1 µm can be obtained. A probe of 0.5 µm to 0.05 µm is obtained when a high-intensity ion source such as a liquid-metal ion source is used. However, the SIMS poses various problems such that this is a destructive analysis because a specimen is sputtered by ions and the elements of the specimen are analyzed by mass analysis of secondary ions discharged, the method is suited to element analysis but not to compound status analysis, and the equipment is large and expensive because a high performance mass analysis function is required. In the EDX, the elements of a specimen are analyzed by analyzing X-ray energy discharged from the specimen by irradiating an electron beam. The spatial resolution ranges from 0.5 to 5 µm because electrons are scattered and spread in the specimen. Therefore, the method is not suited to the object of the present invention. In the AEM, a transmission electron microscope is used for analysis, the resolution is high such as several Å, and not only the elements but also the chemical bonding status can be checked. However, the AEM poses problems such that thin specimens are required and it takes much time to prepare such specimens. Some materials may not be always cut into thin pieces. One of the objects of the present invention is to provide a method and apparatus for processing a minute portion and a method and apparatus for analyzing a minute portion for detecting and correcting pattern defects on the surface or in the interior of an element or substrate with a spatial resolution of 20 nm or less and for detecting and analyzing foreign particles so as to solve the above problems. Another object of the present invention is to provide a minute portion processing mehtod and apparatus and a minute portion analytical method and apparatus for performing various processes such as detecting, analyzing, or processing minute portions, wiring or circuit patterns, or foreign particles of a device or material which are several tens nm in diameter, or film-forming, or annealing. According to the present invention, defects in element patterns ranging from several tens nm in diameter to the atomic size are detected, corrected, or analyzed by using a near-field optical scanning microscope with a scanning tunneling microscope combined as a means for detecting, correcting, or analyzing defects in element patterns. The near-field optical scanning microscope (hereinafter may be abbreviated to NOSM) is on the basis of the principle that when an aperture with a diameter of one-several-tenth to one-several-hundredth of the light wave length is placed at a distance equal to the aperture size from an object, light exists only in an area with a diameter equal to the aperture size in the so-called evanescent wave area (a near field) which is emitted from the aperture when intensive light such as a laser beam is irradiated. This matter is described in U. Dürig et al., "Near Field Optical Scanning Microscope", Journal of Applied Physics, Vol. 159, No. 10, pp. 3318 to 3327 (1978). In this case, light exists only in an area equal in diameter to the aperture size. Therefore, when the aperture is made smaller and the distance between the object and the aperture is made close to the aperture size, the resolution is improved. However, it is practically impossible to make the resolution smaller than the penetration depth of light wave into the interior of the aperture material. An aperture material with a shallow penetration depth is a metal. The penetration depth (so-called skin depth) in this case is about 10 nm. When a laser beam is irradiated to an object as a spot of about 10 nm by this method and the reflected light, transmitted light, and scattered light from the object are removed, a spatial resolution of about 10 nm can be obtained. When the object and the aperture are moved relatively by using a piezoelectric actuator in the same way as with the scanning tunneling microscope so as to allow the light to scan the area where the object exists and the distance between the aperture and the object is kept almost constant during scanning, the light probe can scan a wide area on the object. By synchronizing a signal, which is obtained by detecting the reflected light, transmitted light, or scattered light from the object during scanning, with the scanning and displaying it on the display, an object image or signal image is obtained and the object can be detected or observed. Element patterns can be detected, pattern defects are detected, or foreign particles on elements are detected using the NOSM. Infrared rays, visible rays, or ultraviolet rays are used as a laser beam, or particularly a dye laser with a wide wave length zone is used. By changing the wave length using an etalon, an absorption spectrum or a reflection spectrum of a portion of about 10 nm of an element or a foreign particle of about 10 nm on an element is obtained and the composition can be analyzed. Only an extremely narrow area of about 10 nm of an element can be heated by a laser beam inputted into the NOSM and various processes such as local annealing of an ion implanted area, local recrystallization of a polycrystalline, and removal processing by local bumping or evaporation can be performed. The aperture and object can be filled with gas or liquid, a laser beam can be irradiated to the object in this state so as to decompose the gas or liquid, and the component is deposited locally on the object so as to locally form a film. A nozzle is installed near a specimen and the opening of a light transmission body of the NOSM, and gas can be sprayed during light irradiation. The above gas is a gas for chemical vapor deposition (CVD) of a metal such as an organometal compound, for example, alkyl metal, metal carbonyl, or metal alkoxide or metal halide. The above gas is a gas for chemical vapor deposition of silicon dioxide such as tetraethoxy silane or diethyl silane, or a gas combined with an oxidizing agent gas such as oxygen or hydrogen peroxide. According to the present invention, the NOSM is combined with the scanning tunneling microscope (hereinafter, may be abbreviated to STM) and the combined equipment is used as specified in 111 to 122 indicated below. The present invention provides a minute portion processing method and apparatus for detecting a minute portion of an element or a substrate by the near-field optical scanning microscope and for processing, film-forming, or annealing the detected minute portion with the scanning tunneling microscope. The STM and STS (scanning tunneling spectrometer) are described in detail, for example, in Y. Kuk and P.J. Silverman, "Scanning Tunneling Microscope Instrumentation", Review of Scientific Instruments, Vol. 60, No. 2, pp. 165 to 180 (1989) or K. Kajimura, et al., "Scanning Tunneling Microscope", Solid Physics, Vol. 22, No. 3, pp. 176 to 186 (1987). Means for partially processing elements and forming films using the STM are described in Yamaguchi et al., U.S. Patent Application Serial No. 07/455,155, filed on December 22, 1989, "Method and Apparatus for Processing a Fine Pattern", and the corresponding European Patent Application Publication No. 0 376 045. 111: The position of an element is detected by the NOSM, and a special part is subjected to processing, film-forming, or annealing by the STM on the basis of the information. 112: The position of an element is detected by the NOSM, and a special part is analyzed by the STM or STS on the basis of the information. 121: The position of an element is detected by the STM, and a special part is subjected to processing, film-forming, or annealing by the NOSM on the basis of the information. 122: The position of a special part is detected by the STM and analyzed by the NOSM. By the above configuration, a minute portion ranging from 20 nm to the atomic size can be detected, processed, film-formed, annealed, or ion-implanted, atoms or molecules can be removed or inserted, or foreign particles or defects can be analyzed. ROMs (read only memory) or RAMs (random access memory) can be directly manufactured. Data can be written into or deleted from a memory device. Defects including foreign particles of 20 nm or less existing on the surface of a wafer or element or in the interior thereof can be detected or analyzed. In the accompanying drawings: Fig. 1 is a basic schematic view of an apparatus for detecting and correcting minute patterns or detecting and analyzing foreign particles using a combination of a NOSM and STM relating to the present invention; Figs. 2(a) to 2(f) are drawings showing an embodiment for preparing a NOSM tip; Figs. 3(a) and 3(b) are drawings showing another embodiment for preparing a NOSM tip; Fig. 4 is a drawing showing a further embodiment for preparing a NOSM tip; Fig. 5 is a drawing showing an embodiment that a NOSM tip and a STM tip are mounted independently to a piezoelectric element; Fig. 6 is a drawing showing an embodiment that a NOSM tip moves up and down according to the uneven surface of a specimen; Fig. 7 is a drawing showing an embodiment that a NOSM tip is mounted on the detection side; Fig. 8 is a drawing showing an embodiment that reflected light from a specimen is detected using a NOSM tip; Fig. 9 is a schematic view showing an embodiment of a minute portion processing apparatus of the present invention; Fig. 10 is a schematic view showing an embodiment of a minute portion processing apparatus of the present invention which is different from the embodiment shown in Fig. 9; Fig. 11 is a drawing showing an embodiment that a tip and an optical system rotate; Figs. 12(a) and 12(b) are drawings showing the atom configuration of the (111) surface of Si which is cut from the front; Fig. 13 is a drawing showing the section of the atom configuration of the (111) surface of Si and the needle tip of a STM; Figs. 14(a) to 14(e) are drawings for explaining an embodiment of the present invention which is applied to a memory device; Figs. 15(a) to 15(c) are drawings for explaining an embodiment that a LB film is formed using the present invention; Figs. 16(a) and 16(b) are drawings showing an embodiment of the present invention that data is stored in a memory device wherein 5 molecules constitute one bit. Next, the present invention will be described in detail on the basis of the embodiments shown in the drawings. Fig. 1 is a basic schematic view of an apparatus for detecting and correcting minute patterns or detecting and analyzing foreign particles using a combination of a NOSM and STM relating to the present invention. In Fig. 1, a specimen, for example, LSI 101 is placed on a specimen table 105 with a pattern portion 101a for detection, correction, or analysis down. An XY scanner 102 is an actuator of the bielectrode type or the bielk type using the piezoelectric effect or the electrostrictive effect, and moves on the specimen table 105 in the X or Y direction with the accuracy of less than 1 nm according to the applied voltage by an XY controller 103 on the basis of the power of a ramp generator 106. So as to eliminate the hysteresis of a piezoelectric element or an electrostrictive element or the creep effect, the absolute position is measured by an XY position sensor 104, a negative feedback is applied to the XY controller 103, and the specimen is moved to a correct position. The XY position sensor 104, for example, comprises a light source such as a light emitting diode mounted to the equipment body, a pin hole mounted to the specimen table 105, and a photodetector mounted to the equipment body, and has position detection accuracy of less than 5 nm. In this case, a laser interferometer of the specimen table 105 or a STM, or both of them may be used to measure the position. An output 110 of a light source 109 such as a laser passes through an intermediate optical system 111 connected to an intermediate optical system controller 963, focused by a lens 108, and sent to a NOSM tip 107. The NOSM tip 107 is a quartz glass rod 201 with a tip polished sharply to about 10 nm as shown in Fig. 2(a) and Fig. 2(b) (an enlarged view of the tip) which is deposited with a highly conductive metal thin film 202. When the quartz glass rod is pressed against a flat surface 203, deposited metal 204 at the tip is spread flatwise on the flat surface 203, the deposited metal film 204 at the tip 205 of the glass rod 201 becomes thinner than the so-called skin depth or is removed, causing the glass rod to be exposed. When light is irradiated from the bottom in this state, the light can pass through an extremely narrow area (aperture) of the tip. By doing this, a NOSM tip comprising a sharp tip, an aperture formed at the tip, and an opaque coating around the aperture is formed. The NOSM tip is a needle-shaped light transmission body which is formed so that light passes through only an extremely narrow area of about 10 nm of the tip. The type of the NOSM tip 107 may be different from the type shown in Figs. 2(a) to 2(f). Figs. 3(a) and (b) show another example that a narrow hollow glass tube is melted, lengthened, and cut into pieces. The glasswork technique is required for production. It is possible to produce a tip having a tip portion 302 which is narrow as shown in Fig. 3(a) and an aperture 303 which is narrow such as 10 nm as shown in the same drawing. By depositing a metal thin film on the surface thereof, a NOSM tip 107 can be formed. Since the tip of a NOSM tip formed in this way is sharp, even if the variation range of an uneven surface of a specimen is wide as shown in Fig. 6, the distance between the aperture 303 at the tip and the specimen surface can be kept always at a size nearly equal to the diameter of the aperture 303 by moving the NOSM tip up and down like numerals 107 and 107. The distance between the tip of the NOSM tip 107 and the specimen surface shown in Fig. 1 is controlled by a piezoelectric element 112 in the Z direction and a drive motor 113 in the Z direction. The light 110 from the light source is focused by the lens 108, transmits through the aperture at the tip and the specimen 101, focused by a focusing lens 115, and sent to a detector 116. By measuring the intensity of the detected light at a location with no pattern provided, the distance between the aperture at the tip of the NOSM tip 107 and the specimen surface can be measured. By an instruction provided from a CPU (central processing unit) 952 to a controller 114 on the basis of this intensity, the drive motor 113 in the Z direction or the piezoelectric element 112 in the Z direction can be driven so as to keep the distance constant. Particularly, the distance of the tip is important, and a tunnel current can be used to keep the accuracy at 1 nm or less. A NOSM tip 107, which is pressed and spread, having a minute protrusion 206 at the metal deposited part at the tip thereof as shown in Fig. 2(d) is produced. This protrusion can be formed by pressing the metal film against a flat die with a minute hollow 208 as shown in Fig. 2(e) when pressing a needle to a flat surface as shown in Fig. 2(c). By applying a high voltage to the metal film, for example, by heating it locally by irradiation of a laser beam or power supply after a flat portion is formed as shown in Fig. 2(c), a minute protrusion 206 can be formed as shown in Fig. 2(e). For a NOSM tip 107 of the pipette type shown in Fig. 3(a), a minute protrusion 304 can be formed at the tip in the same way as shown in Fig. 3(b). When the atoms at the tip of the minute protrusion 206 or 304 formed in this way are close to the atoms of the specimen surface and the distance becomes about 2 nm, a tunnel current starts flowing by application of several volts. The needle approaches the specimen by applying several volts between the metal film of the NOSM tip 107 and the pattern of the specimen 101 and stops approaching when a tunnel current is detected. A tunnel current flowing when there is a potential difference of V between a tip, which is at a distance of Z from a surface of a work function , and the surface is expressed by the following equation (3): It = AV Z exp (- BZ  ) where symbols A and B are constants. Therefore, the distance Z can be controlled with extremely high accuracy so as to keep the current It constant. In Fig. 2(f), a minute protrusion 207 is provided at the center of the tip of the NOSM tip 107 in the same way as above. There is an advantage in this case that the distance between the tip and the specimen can be detected immediately by a tunnel current. This provides an advantage that the process by this tunnel current and the optical process by the NOSM can be performed simultaneously or at the same location as described later. Fig. 4 shows another example that a minute protrusion 403 flowing a tunnel current is provided at the center of the tip of the NOSM tip 107 in the same way as in Fig. 2(e). In this case, a glass tip 401 is coated with a metal thin film 402 and pressed against a flat surface so as to spread the tip. Then, a transparent conductive layer 405, for example, SnO 2 or In 2 O 3 is deposited on the spread tip, and pressed against a flat surface with a hollow like 208 so as to spread. By doing this, a protrusion 403 is provided at the location corresponding to the tip 404 of the glass tip 401. There is an advantage that since the tip 107 uses the transparent conductive layer 405, variations in the wave front at the protrusion can be minimized. Particularly, when the refractive index of the transparent conductive layer 405 is made equal to that of the atmosphere between the NOSM tip 107 and the specimen 101, for example, air, variations in the above wave front can be minimized, and the effect of the minute protrusion 403 on the light behavior can be almost eliminated. The tip 404 is an aperture. Fig. 5 shows another embodiment for accomplishing the same object, and the NOSM tip 107 and the STM tip 502 are mounted to the piezoelectric actuator 112 in the Z direction. By doing this, the distance between the tip and the specimen 101 can be measured and controlled by measuring a tunnel current in the STM tip 502. As described later, the process by the STM can be performed at the same location of the specimen as the process by the NOSM by moving the specimen table 105 and the tip relatively by the distance between the tips of the NOSM tip 107 and the STM tip 502. In the method described above with reference to Fig. 1, the light of the NOSM 107 is irradiated to one side of the specimen 101, and the transmitted light is focused by the lens 115 and detected by a detector 116 such as a photomultiplier. Numeral 117 indicates a recorder and 118 an image memory. The tested intensity can be displayed on the recorder 117 or the display of the image memory 118 in synchronization with the output of the ramp generator 106 or of the position sensor 104. The results can be outputted to the CPU 952. To detect the transmitted light in the above case, a specimen is required to transmit light like a photo-mask. Device elements such as LSI wafers are opaque specimens, and it is required to use the reflected light for the NOSM for them as shown in Fig. 8. In this case, the output of the light source 109 such as a laser passes through the intermediate optical system 111, is reflected off of a half mirror 805, focused by the focusing lens 108, passes through an aperture 807 at the tip of the NOSM tip 107, and is reflected off of the surface of the specimen 101a. The reflected output passes through the aperture 807, the lens 108, and the half mirror 805 and is detected by the detector 116 such as a photomultiplier. Since the reflected light can be detected in this case, the specimen 101a may be opaque. For an opaque specimen, the reflected light can be detected by this method. The other points are the same as those specified in Fig. 1. For the transmitted light, a method that the NOSM tip 107 is mounted on the opposite side to the light source 109 for the specimen 101 as shown in Fig. 7 can be used. In this case, the light from the light source 109 such as a laser passes through the intermediate optical system 111 and is focused by the focusing lens 108 so as to form a minute spot 708 on the specimen 101 on the NOSM tip side. The transmitted light passes through the aperture at the tip of the NOSM tip 107, is focused by the lens 115, and detected by the detector 116. The other points are the same as those specified in Fig. 1. Fig. 9 shows an example of a system for detecting, correcting, or analyzing a device element relating to the present invention. The equipment is placed on a vibration-proof table 901. A main unit 902 of a NOSM and/or a STM is installed in a vacuum chamber 900 which is evacuated highly or ultra-highly by an exhaust system such as a turbo-molecular pump 902b or an ion pump 902c, and a laminated vibration-proof rubber sheet 903 or a spring is used for preventing vibration. An XY stage is mounted on a vibration-proof plate 904 comprising laminated rubber and driven by a drive motor 906. A specimen 101 is attached to a holder 909 on a loading mechanism installed in a load chamber 908. The load chamber 908 is evacuated by a rotary pump 911, and the above holder 909 is transported to an XY stage 913 which is moved to the P position with a gate valve 912 open. The gate valve 912 is closed thereafter, the XY stage 913 is moved to the Q position, and the operation such as detection, processing, or analazing is performed. In this case, it is required to stop pumps, which generate vibration, such as the rotary pump 911 and the turbo-molecular pump 902b for rough evacuation. On the basis of a preliminary information file 951 for design data and field test data, a CPU 952 issues an instruction to an XY stage control system 953 so as to move the XY stage 913 so that the area of the specimen 101 requiring detection, correction, or analysis comes almost right under a NOSM tip and/or a STM tip 107. In this case, the distance of a mirror 922 on the XY stage 913 can be measured with high accuracy by a laser length measuring machine 917 through a polarizing prism 918 and a window 919 of the vacuum chamber. A SEM 915 is installed so that the vicinity comes in sight. A SEM controller 915a observes the tip 107 and the specimen 101 as SEM images, and their positions can be checked and adjusted more accurately. From data of SEM images from the SEM controller 915a, the CPU 952 can position the desired minute portion using the target mark, pattern, foreign particle, stain, scratch, or defect on the specimen 101 as a mark. Although not described in detail in the drawing, a drive mechanism 916 of the STM tip and/or NOSM tip 107 in the Z direction comprises a rough mechanism 113 with a long stroke and a highly accurate piezoelectric drive mechanism 112. When the SEM controller 915a connected to the SEM 915 is observing the tip 107 and the specimen 101 as SEM images, the above rough mechanism 113 allows the tip 107 to approach (move to) the specimen 101 and the piezoelectric drive mechanism 916 in the Z direction adjusts the position finely. The detected quantity of the reflected light from the specimen 101 which passes through the NOSM tip and/or STM tip 107 and the detected value of the tunnel current are calculated from an amplifier and comparator 956 and the CPU 952 adjusts the distance between the tip 107 and the specimen 101 with high accuracy. As to the SEM, a bias voltage is applied to the NOSM or STM tip 107 by a bias power source 957, the current flowing between the tip 107 and the specimen 101 is amplified by the amplifier and comparator 956, and compared with the output of a reference voltage source 959 which is fixed beforehand. The difference is amplified and supplied to a drive controller 954 of the piezoelectric element in the Z direction so as to drive the piezoelectric element in the Z direction, and the distance between the specimen surface and the tip can be kept at a predetermined fixed value with high accuracy. A piezoelectric element 920 in the XY direction is driven by a drive controller 955 of the piezoelectric element in the XY direction, the specimen is scanned in the XY direction by an XY scanner 102, and the corresponding drive voltage in the Z direction is displayed on the display. By doing this, the resolution ranging from nm to the atomic size can be displayed on a display and recorder 958. A method that the specimen 101 is driven in the XY direction with the height in the Z direction kept constant and an obtained change in the tunnel current is displayed on the display 958 can be used. Next, the output of a laser resonator 109 driven by a laser resonator power controller 960 passes through an intermediate optical system 111 controlled by an intermediate optical system controller 963, passes through a window 965 of the vacuum chamber 900, and is reflected off of a half mirror 805, focused by an objective lens 108, and irradiated to a minute area on the specimen surface by the NOSM tip 107. The reflected light from the specimen 101 passes through the NOSM tip 107, then passes through the objective lens 108, the half mirror 805, and the window 969 of the vacuum chamber, and is detected by a detector 116 and amplified by an amplifier 971. Since the reflectivity of the specimen 101 is almost constant at any location, the output of the reflected light is amplified by the amplifier and comparator 956 and compared with the voltage of the reference voltage source 959 which is preset. The difference is supplied to the drive power source 954 of the piezoelectric element in the Z direction so as to keep the distance between the specimen 101 and the NOSM tip 107 in the Z direction almost constant. By doing this, a STM image or a NOSM image is detected by the STM tip 502 or the NOSM tip 107, a high resolution image at a necessary location is obtained with reference to the data file, which is stored in the preliminary information file 951 once again, or other data such as SEM images, and a minute portion in the desired range from 20 nm to the atomic size can be detected, processed, annealed, or analyzed by the STM, STS, or NOSM. The equipment shown in Fig. 9 is equipped with a mechanism for charging gas around the specimen. Gases which can be used are as follows: (1) Gases for chemical vapor deposition (CVD) of a metal (a) Alkyl metal: M(CnH2n+1)m, for example, Al(CH 3 ) 3 , Al(C 2 H 5 ) 3 , Al(C 4 H 9 ) 3 , Cd(CH 3 ), Cd(C 2 H 5 ) 2 (b) Metal carbonyl: M(CO)n, for example, Mn(CO) 6 , W(CO) 6 (c) Metal alkoxide: M(OCnH2n+1)m, for example, Ta(OC 2 H 5 ) 5 (d) Metal halide: MX, for example, WF 6 , WCl 6 (2) Gases for CVD of oxide film or nitride film TEOS (Tetra etoxy silane), DES (Diethyl silane), oxidizing gas, nitriding gas, O 2 , N 2 O 2 , H 2 O 2 (3) Gases for CVD of semiconductor materials or impurity materials SiH 4 , A 6 H 3 , PH 3 , Ga(CH 3 ), Ga(C 2 H 5 ) 3 , In (CH 3 ) 3 , H 2 Se, H 2 S, Zn(C 2 H 5 ) 2 (4) Assist gases for dry etching F 2 , Cl 2 , XeF, ArF One of these gases, which is gaseous at normal temperature, for example, F 2 or Cl 2 is taken out from a cylinder 980 via a valve 984. In this case, the above gas can be mixed with dilution gas separately contained in a cylinder 983 by a gas mixer 990. A solid, which is sublimed at normal temperature, for example, Mo(CO) 6 is sublimed in a box 987 beforehand. In this case, a heater 989 mounted to the box 987 can be used so as to accelerate sublimation by heating. Carrier gas contained in a cylinder 981 is fed to the cylinder 987 via a valve 984 so as to transport gas from the solid. Furthermore, a liquid, which is liquefied at normal temperature, for example, trymethylaluminum Al(CH 3 ) 3 is supplied into a bubbling container 988 from a cylinder 982 via a valve 984 and bubbled by carrier gas such as N 2 , which is separately fed, so as to allow a part of the liquid material to be dissolved in the carrier gas as vapor. The dissolved gas is transported with the carrier gas. These gases can be used independently or a plurality of gases can be mixed by the mixer 990 before starting use. Finally, these gases are supplied to the vacuum chamber 900 via a flow regulating valve 991 and ejected to the specimen 101 and its vicinity from a gas guide nozzle 992 mounted to the lens tube of the SEM 915. In Fig. 9, the intermediate optical system 111 can be used together with various optical systems shown below when necessary. (1) Lenses and mirrors for adjusting the optical axis direction or the beam diameter (2) A polarizing filter or polarizer for fixing or changing the polarizing direction or a ND filter for adjusting the intensity (3) A wave length selection filter for selecting a special wave length from a multi-wave laser such as an ion laser or from a laser with a wide wave length zone such as a dye laser (4) An optical system for reducing the coherence of the laser resonator used (5) Others Fig. 10 shows an embodiment wherein a focused ion beam-processing system (FIB apparatus), a tilt mechanism of the specimen stage, and a tilt mechanism of the NOSM and/or STM tip are added to the equipment shown in Fig. 9. A focused ion beam column 1079 other than the one shown in Fig. 9 may be used as a vacuum chamber 900. The column focuses an ion beam from a high-intensity ion source 1074 such as a liquid-metal ion source by electrostatic lenses 1075 and 1077 to a narrow beam and irradiates it to the specimen 101. Particularly by using a combination of the first electrostatic lens 1075 and the second electrostatic lens 1077, the ion beam can be focused to a spot 60 nm to 30 nm in diameter on the specimen surface. Numeral 1076 indicates an eight-pole electrode serving as an anastigmat and a deflector, which corrects the astigmatism of the beam or polarizes the beam. Numeral 1078 indicates a deflector electrode, which polarizes the beam together with the eight-pole electrode 1076. A minutely focused ion beam can be sputtered by irradiating it to an extremely narrow area. By detecting secondary electrons or secondary ions generated from an irradiated specimen by a secondary charged particle detector 1083 such as a channel plate, a specimen image which is similar to a SEM image or an image of scanning ion microscopy (SIM image) can be obtained. In this case, the processing is progressed simultaneously with observation. Therefore, by minimizing the scanning count for observation by storing images in an image storage unit 1082 by one scanning, images for processing during observation can be minimized. Numeral 1080 indicates an ion source controller and 1081 an electrode controller which is connected to a CPU 952. The image storage unit 1082 is also connected to the CPU 952. The tilt mechanism of the specimen stage is a concentric tilt mechanism which minimizes the displacement of the beam caused by the rotation whose center is the position where the beam is irradiated. The tilt mechanism comprises a mount 1071c, whereto a gear 1073 is mounted, and a stage 1071d which are installed on the XY stage 913 using supports 1071a and 1071b. The gear 1073 rotates round an axis perpendicular to the paper, where Fig. 10 is drawn, centering at the beam irradiation point A on the specimen 101 according to a signal from the controller 955 (shown in Fig. 9) and the power by a vacuum motor, and can stop at an optional angle. By doing this, it is possible to observe an image or irradiate a beam at an optional angle. Even when the XY stage 913 moves to the position Q of the NOSM and/or STM tip and the SEM, it rotates by the tilt mechanism and can be opposite to the SEM or the NOSM and/or STM tip at an optional angle. When the specimen is to be exchanged at the specimen exchange position P, the specimen table 105 is required to be horizontal. It is desirable to indicate the stage, mount, uniaxial stage, or specimen, which is at the position Q or P, with broken lines. However, solid lines are used so that the units can be clearly recognized. The specimen table 105 is required to be horizontal. In Fig. 10, the support 1071d is a uniaxial stage which can move on the mount 1071c fixed to the gear 1073 so as to move the specimen 101. Even when the support 1071d moves, the height of the ion beam irradiation position is left unchanged, and there is no need to change the beam focus when the stage 1071d moves or the gear 1073 rotates. The NOSM and/or STM tip shown in Fig. 10 is characterized in that the tip has a mechanism that it rotates round the end point of the tip. The mechanism will be described in detail hereunder. As shown in Fig. 11, a lens tube 1100, which has a rotation axis located at the same level as the surface of the specimen 101 and is supported so that it can freely rotate, is installed on a base 1112 mounted on the vibration-proof plate 904. A gear 1113 is mounted on the side of said lens tube 1100, and a gear 1114, which is engaged with the gear 1113, is mounted to the output axis of a drive motor 1115. The main unit 902 of the NOSM and/or STM having the NOSM and/or STM tip 107 and 502 is mounted at the tip of the above lens tube 1100. The main unit 902 of the NOSM and/or STM has a drive mechanism 916 (112, 113) comprising a combination of a rough mechanism 113 with a long stroke and a piezoelectric drive mechanism 112 with high precision in the Z direction. The lens tube 1100 comprises a mirror 1110, a lens 108, and two mirrors 1111. A half mirror 805 is positioned at the center of the rotation axis of the lens tube 1100 via a mirror 1116. A fixing means for fixing the lens tube 1100 to the base 1112, that is, the vibration-proof plate 904 after rotating the lens tube 1100 so as to control the rotation of the NOSM and/or STM tip 107 and 502, which is not shown in the drawing, is provided. Next, the technique, which is applied to the above embodiment, will be described. Figs. 12(a) and 12(b) and Fig. 13 show the atom configuration of the (111) surface of Si, and the correct (7x7) structure has been made clear by the STM for the first time. Figs. 12(a) and 12(b) show the atom configuration which is cut from the front, and Fig. 13 shows a sectional view on the line AB. The so-called reconstructed layer near the surface comprises dimers (Z corpus quantum), stacking faults, and absorption atoms. The atom configuration of the dimer layer is almost the same as that of the (111) lattice plane of crystal, and three dimers are formed along each side of two triangles of sub-unit cells. Each angle contains a vacancy of atom. The dimer gap is longer than the general Si-Si bond length by 9%. Si atoms of the stacking fault layer are at the C position in the sub-unit cell on the left and at the B position on the right. As to absorption atoms, there are six absorption atoms in a sub-unit cell and their positions are fixed. Absorption atoms can be separated and read by the STM so as to configure an extremely high density memory device. As shown in Fig. 12(b), for example, a diamond-shaped cell (unit cell) can be expressed by polar coordinates (m,n) using symbols m and n which indicate the numbers of cells on the axes, which intersect at 60°, between the cell and the same reference point O. One unit cell contains 12 absorption atoms. By determining the coordinates as 1, 2, and 3 in the P axis direction and 1, 2, and 3 in the Q axis direction sequentially starting at the lower left vertex in the lower left sub-unit cell and by determining the coordinates as 1 , 2 , and 3 in the P axis direction and 1 , 2 , and 3 in the Q axis direction sequentially starting at the upper right vertex in the upper right sub-unit cell, all absorption atoms can be specified by (i,j) (|i| ≦ 3, |j| ≦ 3, |i+j| ≦ 4). Therefore, every absorption atom on the Si surface of the (7x7) structure of a perfect (111) plane can be specified by (m,n,i,j) (m, n, i, and j are integers except 0, and |i| ≦ 3, |j| ≦ 3, |i+j| ≦ 4). The needle tip of the STM approaches the Si surface as shown in Fig. 13 and keeps a predetermined distance of δ to the absorption atom H 1 at the particular coordinates (m 1 , n 1 , i 1 , j 1 ) by detecting an image and tunnel current, and then advances by a predetermined distance of δ' in the Z direction. By doing this, a hole is formed at the location of the H 1 atom by plastic deformation. Next, the needle tip is pulled up, and then moves to the next position (m 2 , n 2 , i 2 , j 2 ), keeps the predetermined distance δ to the H 2 atom by detecting the tunnel current in the same way, and then advances by the predetermined distance δ' in the Z direction so as to form a hole at the location of the H 2 atom. By repeating this operation, a hole can be formed at the location of the absorption atom H k at the particular coordinates (m k , n k , i k , j k ) so as to create a ROM (read only memory). A method that the needle approaches to a predetermined distance from the atom H k , the tunnel current is increased by increasing the applied voltage, and the absorption atom is given large energy and separated from the Si surface may be used. Since the absorption atom is not subject to plastic deformation in this case, a method that SiH 4 is reversely decomposed and Si is deposited may be used for separating the absorption atom and giving a Si atom in the hole. By this method, a RAM (random access memory) for writing or erasing data in or from the (111) surface of Si can be configured. Furthermore, by flowing a tunnel current in a reactive gas (F 2 , Cl 2 , etc.), Si atoms can be changed to stomatal materials, volatilized, and eliminated. The technique mentioned above uses the atom configuration (7x7) of the (111) surface of Si as a memory device. An optional crystal face such as Si (110) may be used instead of Si (111), and the technique may be used for another element or molecule configuration. Figs. 14(a) to 14(e) show embodiments of another memory device. A LB film (Langumuir-Blodgett's film) is formed on a substrate, for example, a glass substrate or a Si substrate. As shown in Fig. 15(a), for example, a glass substrate is subjected to the hydrophobic processing by (CH 3 ) 3 SiOH, and as shown in Figs. 15(b) and 15(c), a LB film is formed on the glass substrate using a long chain compound such as carboxylic acid or carboxylic acid alkali. When one LB film is formed, (CH 2 ) n COOH is uniformly bonded to a layer as shown in Fig. 14(a). It is assumed that 1 bit is allocated to each molecule and the bits are all 0. The STM detects the molecules one by one, and a large STM current is flowed in a molecule at a specified location so as to dissociate the bond with the substrate and eliminate the molecule. This state is assumed as 1. By doing this, data is written into the memory as shown in Fig. 14(b). This reading is performed by the STM in the same way. Figs. 14(a) to 14(e) show sectional views, though the molecules are spread on a two-dimensional plane. In Fig. 14(c), two LB films are formed. In this case, (CH 2 ) n COOH and HOOC(CH 2 ) n are hydrophilic radicals and hydrogen-bonded. By flowing a large current in a HOOC(CH 2 ) n molecule at a specified location by detection of the STM, the hydrogen bonded section can be separated so as to eliminate the upper layer of HOOC(CH 2 ) n . Fig. 14(e) shows an example that the memory device is used as a multi-value memory. By using a method that a current, which flows in (CH 2 ) n COOH-HOOC(CH 2 ) n at a specified location by the STM tip, changes in magnitude depending on an change in the applied voltage, the bond between the upper layer of molecules and the lower layer of molecules is dissociated, and whether or not to separate the bond between the lower layer of molecules and the substrate can be selected. By allocating 0, 1, or 2 to each bit on the assumption that the former is 1 and the latter is 2, a three-value memory can be configured. Fig. 16 shows an example that a memory device is configured by allocating a bit to 5 molecules (5 x 5 = 25 molecules on a plane). Light is irradiated to specified molecules in bit units by the NOSM, those molecules are eliminated by melting evaporation or photo-chemical dissolution, and data is recorded as shown in Fig. 16(a). In Fig. 16(b), the above multi-value memory is used. Although 1 bit is allocated to 5 x 5 = 25 molecules in the same way, two LB films are used and 1 or 2 is written by selecting whether only the molecules on the upper film are subject to melting evaporation by controlling the intensity of the light which is irradiated by the NOSM or the molecules on the lower film are also subject to melting evaporation. O is indicated at locations where nothing is eliminated in the same way. By measuring the height by the STM or detecting the intensity of the transmitted light or the reflected light or spectrums by the NOSM, the value 0, 1, or 2 of each bit can be read. The bond can be dissociated selectively by changing the light wave length instead of the above technique for changing the light intensity. By selecting a specified wave length from the output of a multi-wave argon laser or the output of a dye laser with a wide spectrum width using a wave length selection filter by Fabry- verot etalon or an absorption wave length selection filter and selecting whether the bond between the molecules on the upper layer of the two-layer molecular structure and the molecules on the lower layer is to be dissociated or the bond between the molecules on the lower layer and the substrate is to be dissociated, 1 or 2 can be written. As described above, the present invention obtains good results that a minute portion ranging from 20 nm to the atomic size can be detected, processed, film-formed, annealed, or ion-implanted, atoms or molecules can be removed or inserted, or foreign particles or defects can be analyzed. Furthermore, the present invention obtains good results that a ROM or RAM can be directly configured and data can be written in or erased from a memory device. Furthermore, the present invention obtains good results that defects including foreign particles of 20 nm or less existing on the surface or in the interior of a wafer or device element can be detected or analyzed.

Claims: A method for processing a minute portion of an element or substrate of a device (101) comprising the step of detecting an image of said minute portion by means of near-field optical scanning microscope (NOSM) with a tip (107) having an aperture (105, 303, 404, 807) through which light can be emitted onto said minute portion to detect an image therefrom, characterized by the further steps of controlling, preferably keeping constant, the distance between said minute portion and tip (107) by controlling a minute-movement mechanism (112) in accordance with the image detected by said near-field optical scanning microscope, and subjecting said minute portion to at least one step of processing, film forming or annealing by means of a scanning tunneling microscope (STM) with a tunnel current flowing between a tip ( 206, 207, 304, 405, 502), preferably formed on the tip (107) of said near-field optical scanning microscope, and said minute portion. A method according to claim 1, characterized by preceding steps of detecting a relative displacement of said minute portion and said tip (107) by means of a scanning electron microscope (SEM) (915) according to a scanning electron microscope image, created by observing said minute portion, and positioning roughly said minute portion to the tip (107) of said near-field optical scanning microscope by means of a rough-movement mechanism (113) in accordance with the detected relative displacement. A method according to claim 1, characterized in that data relating to said minute portion is written on a memory device. An apparatus for processing a minute portion of an element or substrate of a device (101) comprising a near-field optical scanning microscope (NOSM) with a tip (107) having an aperture (205, 303, 404, 807) through which light can be emitted onto said minute portion to detect an image therefrom, characterized in that the apparatus further comprises means for controlling, preferably keeping constant, the distance between said minute portion and tip (107), said means controlling a minute-movement mechanism (112) in accordance with the image detected by said near-field optical scanning microscope, and a scanning tunneling microscope (STM) with a tunnel current flowing between a tip (206, 207, 304, 405, 502), preferably formed on the tip (107) of said near-field optical scanning microscope, and said minute portion for subjecting said minute portion to at least one step of processing, film forming or annealing. An apparatus according to claim 4, characterized in that the apparatus further comprises a scanning electron microscope (SEM) (915) for detecting a relative displacement of said minute portion and tip (107) according to a scanning electron microscope image, created by observing said minute portion, and means for positioning roughly said minute portion to the tip (107) of said near-field optical scanning microscope, said means controlling a rough-movement mechanism (113) in accordance with the detected relative displacement. An apparatus according to claim 4, characterized in that the apparatus further comprises means for writing data relating to said minute portion on a memory device.

Inventors: KOHNO MAKIKO, NAKATA TOSHIHIKO, NOGUCHI MINORI, YAMAGUCHI HIROSHI, KOHNO, MAKIKO, NAKATA, TOSHIHIKO, NOGUCHI, MINORI, YAMAGUCHI, HIROSHI, KOHNO, MAKIKO, OF NO.203 SUTOOKU-HAIMU
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1991
Main classification: G02B21
IPC codes: H01J37, G01Q70, G01Q60, G01Q30