JP2004318091A - Method eor correcting black defect of mask by applying electrochemical technique to afm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a black defect correction technique which can cleanly correct black defect in fine patterns in black defect correction of a mask without causing the riverbed in black defect correction of the mask, does not exert damage by ion irradiation to the mask surface, is relatively simple in the device to be used without enlarging and enables the relatively simple conduction of the work, and to provide the device capable of executing such technique. <P>SOLUTION: The black defect correction technique of the mask comprises recognizing the position of a black defect section of the mask by an atomic force microscope (AFM), moving the probe of the AFM upward of the black defect position, and removing the black defect by electrochemical reaction in the state of interposing an electrolyte between the probe and the black defect section as both electrodes and further comprises confirming the removal of the black defect by the AFM. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for correcting a black defect in a photomask used for manufacturing a semiconductor, an apparatus for executing the method, an AFM probe used for the apparatus, and a method for manufacturing the same.

  Recent electronic devices such as personal computers and mobile phones have been made smaller and have higher performance largely due to higher density and systematization of LSIs. In the situation where millions of elements or more are packed in a semiconductor chip of only a few millimeters square, the line width for drawing circuit patterns is also on the order of microns to nanometers, and lithography technology development to realize that is required. It is unfolding. Until now, the mainstream of lithography was optical lithography technology.However, the wavelength of light used in response to miniaturization of patterns should be as short as possible, and laser processing with a short wavelength will be used. Due to the problems of optical systems and resists, the response to miniaturization by an optical exposure apparatus is reaching its limit. Therefore, technologies that use electron beams or ultra-short ultraviolet rays as the source of light are promising prospects for replacing light, and photomasks used with these technological trends are becoming finer in pattern. . If a defect is present on the photomask, the defect is transferred to the wafer and causes a decrease in yield. Therefore, before transferring the mask pattern to the wafer, the defect inspection device examines the presence / absence and location of the defect in the photomask. In the case where a defect exists, a defect correction process is performed by a defect correction device before transfer to a wafer. This mask defect correction also requires fine processing as the pattern becomes finer.

  Defect correction of exposure masks used in lithography has also been corrected using laser beams. Currently, however, the etching function of a focused ion beam (FIB) device with excellent processing accuracy and work efficiency has been developed. The mainstream is removal of attached foreign matter (correction of black defects) and addition of missing portions (correction of white defects) using an ion beam-induced deposition function. Conventionally used photomasks are a light shielding film by depositing a binary mask material such as chrome or a halftone phase shift mask material such as MoSiON on a glass such as quartz glass by sputtering, and the mask pattern is used as a light transmittance. In recent years, Levenson-type phase shift masks, which have been dug up to the opposite phase of the glass and have a stronger resolution and depth of focus, are beginning to be put to practical use. . In such a technical situation, the phenomenon of the riverbed at the time of performing the black defect correction by irradiating the ion beam has become a more serious problem. The riverbed is a phenomenon in which when an ion beam is irradiated to a peripheral portion of a defect, ions reflected by the defect are scattered and the substrate around the defect is etched. Further, although the ion beam is finely focused by the optical system, it has a microscopic normal distribution, which also contributes to the riverbed phenomenon that etches the substrate around the defect. Since the riverbed disturbs the phase of the transmitted light due to the difference in height, it adversely affects the transfer result and is a factor of deteriorating the processing quality at the black defect correcting portion. In particular, due to the shortening of the wavelength of the light source of the recent reduction projection exposure apparatus, even a riverbed having a depth that is not a problem in the past has affected the transfer result. Further, in the etching using the FIB, there is also a problem that the material once removed by sputtering is attached again to the glass substrate.

  In view of the problem of the FIB processing such as the riverbed, the present applicant has previously presented Patent Document 1 “Method of correcting black defect of mask”. This means that the tail component of the ion beam and the ion beam scattered at a small angle in the first stage are irradiated only to the inside of the defect area recognized so as not to hit the surrounding glass part, and etching to leave the edge of the defect is performed. Performing a two-step correction procedure of physically shaving only the edge of the defect left in the second step with a hard probe of an AFM fixed to the height of the glass surface to correct the black defect, By combining a defect repair apparatus using an ion beam with an atomic force microscope (AFM), it is possible to repair a black defect without a riverbed with a practical throughput.

  However, in order to perform defect correction by this method, it is necessary to perform FIB processing in a vacuum chamber and then to take it out of the chamber and perform an AFM operation. This operation has a problem that it is a troublesome operation of accurately positioning the probe at the peripheral edge of the remaining defect, scanning the probe, and mechanically shaving the probe.

  In addition, in order to perform defect correction by this method, it is necessary to perform a troublesome operation of accurately positioning the probe position on the peripheral edge of the remaining defect and mechanically shaving it. Therefore, there has been a problem that the work is considerably troublesome. In addition, there is a problem that the mask surface is damaged when an ion beam is scanned to obtain a secondary charged particle image for observing a defective portion, and a FIB drift occurs due to a charge-up phenomenon due to ion beam irradiation, resulting in a positioning failure. There was also the problem that it would be accurate.

  Therefore, the present applicant has conceived of removing the mask defect portion by an electrochemical method since the material thereof is a conductive material such as chromium, and is proceeding with development. The reaction of dissolving the defect material in the electrolytic solution by the electrochemical method does not damage the surrounding glass substrate and can control the reaction rate, so it meets the requirements required in that respect, The problem is to realize a process for removing only a defective portion which is a microstructure by this method. Considering the current state of photomasks, it is necessary to specify a local region of ten to several hundred nanometers to cause a reaction.

  Further, in order to perform defect correction by this method, both functions of a focused ion beam (FIB) device and an AFM are required. Therefore, the size of the device needs to be increased, and the work must be performed by handing the sample to be processed to both devices. No. Even when this is performed by a combined device having both functions, the FIB processing must be performed in a vacuum chamber, and then, the FIB processing must be performed outside the chamber to perform an AFM operation. Moreover, it is a troublesome operation to accurately position the probe at the peripheral edge of the remaining defect and mechanically scrape it. Therefore, there was a problem that neither the device nor the operation was simple. In addition, the mask surface is damaged when the ion beam is scanned to obtain a secondary charged particle image for observing a defective portion, and the positioning becomes inaccurate due to a charge-up phenomenon caused by ion beam irradiation. There was also a problem.

  Therefore, the present applicant is working on conceiving that the material of the mask defect portion is a conductive material such as chromium, which will be removed by an electrochemical method, as will be described later. . The reaction of dissolving the defective material in the electrolytic solution by the electrochemical method does not damage the surrounding glass substrate, so it satisfies the requirements required in that respect, but the problem is the fine structure The purpose of this method is to remove only the defective portion. Considering the current state of photomasks, it is necessary to specify a local region of ten to several hundred nanometers to cause a reaction. In addition, this correction method using an electrochemical reaction has a disadvantage in that a longer processing time is required as compared with etching correction using a conventional FIB apparatus.

  By the way, as an example of performing fine processing using an electrochemical technique, there is a technique disclosed in Patent Document 2, but this technique is intended to form a semiconductor mask pattern itself by an electrochemical technique. . That is, a conductive cantilever having a conductive probe capable of detecting an atomic force generated between the sample and a workpiece, and a displacement generated by the atomic force between the probe and the sample to be processed are detected. Control means for maintaining a constant distance between the probe and the sample in order to maintain the atomic force at a constant level when scanning the sample to be processed; And a means for applying an electric potential between the sample and the probe, comprising a device having an atomic force detecting means, wherein a non-water-containing non- This is a fine processing method for performing fine processing on a sample to be processed by applying a voltage to the probe in the presence of a polar solvent. Although this document mainly discloses a method using a processing method for removing a surface layer by an electrochemical reaction, it is not easy to remove unnecessary regions over the entire mask by this method.

  The present invention proposes a technique for accurately correcting a next-generation mask defect having a fine pattern structure using an atomic force microscope (hereinafter, referred to as an electrochemical AFM) having the electrochemical processing function. However, for that purpose, a local region of ten to several hundreds of nanometers must be specified to cause a reaction. In order to realize a local reaction, the fineness of the electrode facing the defect, the distance between the two, and the amount of charge are important conditions. Therefore, when using a probe of a probe microscope as an electrode, a conductive probe whose tip diameter is sharpened to several to several tens of nanometers is used as an electrode, and this thin electrode is positioned at a close distance of 1 to 100 nanometers. By doing so, a desired local reaction can be realized. However, it is not easy to process the tip diameter of the probe to the order of 1 nanometer and to form a conductive electrode structure only at the tip.

  By using an atomic force microscope (AFM), which is a kind of a probe microscope, an observation image specifying a defect position can be obtained without using a focused ion beam.

The present invention provides a method for producing a suitable probe using the electrochemical AFM and a probe produced by the method. The reaction of dissolving the defective material in the electrolytic solution by the electrochemical method does not damage the surrounding glass substrate, and the reaction rate can be controlled. In this respect, the present invention solves the problem of mask correction using a focused ion beam device. However, in the case of using this method, it is important to realize processing for removing only a defective portion having a fine structure. Since the material of the black defect in the mask is also the material of the mask pattern, if the original mask pattern is removed by this electrochemical method, a new white defect will be created and the defect will not be corrected.
JP-A-2002-214760, Seiko Instruments, "Method of correcting black defect of mask", published on July 31, 2002. JP-A-2002-355799, Hokkaido T.L.O., "Fine processing method and information recording method", published on December 10, 2002. JP-A-7-174542, Seiko Instruments, "Scanning Near-Field Atomic Force Microscope, Probe Used in the Microscope, and Method for Manufacturing Probe", published July 14, 1995.

  The basic problem to be solved by the present invention is that a riverbed cannot be formed in correcting a black defect of a mask, a black defect in a fine pattern can be finely corrected, and the mask surface is not damaged by ion irradiation, In addition, it is an object of the present invention to provide a black defect repairing method that can use a relatively simple apparatus that does not increase in size and that can perform the operation relatively simply, and to provide an apparatus that can execute such a method.

  A further problem to be solved by the present invention is to provide a black defect correction method which can perform local fine correction without a positional deviation due to a charge-up phenomenon, and can perform the operation relatively simply. In addition, it is possible to present a black defect correction method that can perform a local fine correction without affecting the surrounding pattern in the mask black defect correction and that can perform the operation relatively simply, and can execute such a method. It is to provide a device.

  Another object of the present invention is to provide a probe for an electrochemical AFM having a tip diameter on the order of nanometers in order to realize the above method.

  The method of correcting a mask black defect according to the present invention includes the steps of: grasping a position of a black defect portion of a mask by an atomic force microscope; moving a probe of the atomic force microscope above the position of the black defect; Removing the black defect by an electrochemical reaction with the mask black defect portion serving as both electrodes and an electrolyte interposed therebetween, and confirming the removal of the black defect by the atomic force microscope. .

  Further, another method for correcting a mask black defect according to the present invention includes a step of grasping the position of a defective portion of the mask by an observation function of the AFM, a step of applying an insulating resist film on the mask surface, and a step of removing the resist film at the defective portion. Scratching with an AFM probe, moving the electrochemical AFM probe above the defect position, and performing an electrochemical reaction with the probe and the mask black defect as both electrodes and an electrolyte interposed therebetween. And removing the insulating film on the mask surface.

  Further, another method for correcting a mask black defect according to the present invention includes a step of grasping a position of a defective portion of the mask by a scanning microscope, a step of applying an insulating resist film on the mask surface, and a step of applying a resist film of the defective portion. Irradiating with a charged particle beam, moving a probe of the electrochemical AFM above the defect position, and using the probe and the mask black defect portion as both electrodes and interposing an electrolytic solution. The step of removing the black defect by an electrochemical reaction, and the step of removing the insulating film on the mask surface.

  In another method for correcting a mask black defect according to the present invention, any one of an AFM, a scanning ion microscope, and a scanning electron microscope is used as a scanning microscope for obtaining defect position information.

  In addition, another method of correcting a mask black defect according to the present invention includes a step of grasping the position of a defective portion of a mask by a scanning microscope function of an FIB apparatus, and irradiating a FIB to a central portion of a defective region excluding a peripheral portion to obtain a vicinity of a glass substrate. Etching, leaving a black defect remaining by an electrochemical reaction with the probe and the mask black defect as both electrodes and an electrolyte interposed therebetween, and removing the defect by an atomic force microscope. Confirming the modification.

  In another method for correcting a mask black defect according to the present invention, before an electrochemical reaction, a step of measuring a tunnel current flowing between the probe and the black defect and setting an appropriate close distance is performed. Adopted.

  The black defect correction method of the present invention specifies a defect correction position from an atomic force microscope image as a first step, and a distance between a conductive probe tip and a conductive mask material as a second step. Is set using a tunnel current, an electrochemical reaction occurs between the black defect portion and the probe, and processing is performed until the glass surface is exposed. The third step is to check whether the correction has been completed using an atomic force microscope.

  The mask black defect repair apparatus of the present invention is a probe of an atomic force microscope having a tip portion as an electrode, a processing cell for storing an electrolyte and a mask as a sample, and the tip portion of the probe and the mask surface. A power supply for applying a predetermined current or a predetermined voltage therebetween, and a mechanism for moving the position of the tip of the probe in the X, Y, and Z directions. It has a processing function to remove by a mechanical reaction. In order to locally limit the electrochemical reaction, the probe was formed of a conductive material and the surface thereof was covered with an insulating material, and only the tip was exposed.

  Another mask black defect correcting apparatus of the present invention includes an AFM probe having only a tip portion as an electrode, a processing cell for storing an electrolyte and a mask as a sample, and a probe tip and a mask surface. A power source for applying a predetermined current or voltage between the probe and a mechanism for moving the position of the tip of the probe in the X, Y, and Z directions. A function of observing the shape of the probe, a function of moving the probe to the position based on the defect position information obtained by the observation, and a function of mechanically removing the resist film on the defect surface, and using a tip electrode of the probe. It has a processing function to remove mask black defects by an electrochemical reaction.

  Another apparatus for correcting a mask black defect according to the present invention has a function of mechanically removing a resist film on a defect surface. A computer is provided which determines a removal area and issues a drive signal to a mechanism for moving the position of the tip of the probe in the X, Y, and Z directions so as to scan the removal area.

  Further, another mask black defect repairing apparatus of the present invention includes an FIB apparatus including a FIB column and a sample stage having at least a three-dimensional driving mechanism in a vacuum chamber, and an AFM probe having only an end portion as an electrode. A processing cell for accommodating an electrolyte and a mask as a sample, a power supply for applying a predetermined current or voltage between the probe tip and the mask surface, and a position of the probe tip in X, Y, and X directions. It has a mechanism for moving in the Z direction, and has an observation function and a processing function of removing a mask black defect by an electrochemical reaction.

  Further, another mask black defect repairing apparatus of the present invention includes an electron beam apparatus including a sample stage having an electron beam column and at least a three-dimensional driving mechanism in a vacuum chamber, and an AFM probe having a tip portion as an electrode. A processing cell for accommodating an electrolytic solution and a mask as a sample; a power source for applying a predetermined current or voltage between the probe tip and the mask surface; , And a mechanism for moving in the Z direction, and has an observation function and a processing function of removing a mask black defect by an electrochemical reaction.

  Further, another mask black defect repair apparatus of the present invention includes a FIB apparatus having a SIM function for grasping a defect position and an etching function by beam irradiation, a probe of an atomic force microscope having a tip portion as an electrode, and an electrolytic solution. A processing cell for accommodating a liquid and a mask as a sample, a power source for applying a predetermined current or a predetermined voltage between the tip of the probe and the mask surface, and a position of the tip of the probe in X, Y, and Z directions. And an electrochemical AFM device having a processing function of removing a mask black defect by an electrochemical reaction based on the defect position information obtained by the FIB device.

  Furthermore, in order to perform minute correction of minute areas, only the tip is made of a sharp conductive material and used as an electrode, and the other part is made of an insulator. The power supply connected between the surface and the surface is capable of supplying a bias voltage and a pulse of a predetermined current or a predetermined voltage, and a mask black defect such as an appropriate close distance between the probe tip and the mask black defect can be set by the STM function. Was adopted in which the electrochemical reaction was locally performed.

  According to another mask black defect correcting apparatus of the present invention, the power supply connected between the tip of the probe and the mask surface can supply a bias voltage and a pulse of a predetermined current or a predetermined voltage. In addition to the processing function to remove defects by electrochemical reaction, it has an STM function to measure and set an appropriate closest distance between the probe and the mask black defect.

  The method of manufacturing a probe for an electrochemical AFM according to the present invention includes a step of roughly processing a plate-shaped cantilever portion and a probe portion projecting from the tip thereof from an SOI silicon wafer by dry etching; A step of advancing oxidation from the surface by thermal oxidation to sharpen the tip, a step of coating the surface of the probe and cantilever with a metal thin film, and an insulating layer except for the tip and the contact hole of the probe. Coating step.

  In another method of manufacturing a probe for electrochemical AFM of the present invention, as a step of roughly processing a plate-shaped cantilever portion and a probe portion protruding from the tip thereof from the SOI silicon wafer, mask patterning and reactive ion implantation are performed. An etching method was adopted.

  In another method of manufacturing a probe for an electrochemical AFM according to the present invention, as a step of covering the tip with the insulating layer except for the tip and the contact hole, the whole is covered with an insulating film, and then the tip with the probe is contacted. A method of removing holes by plasma etching was employed.

  In another method of manufacturing a probe for an electrochemical AFM according to the present invention, as a step of coating the probe tip with an insulating layer except for the contact tip and the contact hole, the entirety is covered with an insulating film, and then the probe tip and a contact are formed. The holes were removed by the FIB etching technique.

  In another method for producing a probe for electrochemical AFM of the present invention, a step of sharpening a hollow glass capillary in a heated state and a step of heating and cooling the sharpened tip a plurality of times to bend in one direction. A step of inserting a metal wire into the capillary, a step of sealing both ends of the capillary with a resin, and a step of sharpening the tip by electrolytic polishing. Further, a step of dip coating the probe that has passed through the step in a molten apiison wax, a step of polishing the back surface of the probe to form a mirror surface, and a step of sputter coating a metal thin film around the mirror surface, And dipping in chloroform to dissolve the Apiezon wax to remove the metal thin film other than the mirror surface.

  The probe for electrochemical AFM of the present invention is formed of a conductive material, and its surface is covered with an insulating material, and only the tip is exposed.

  In the electrochemical AFM probe according to the present invention, the basic structure of the plate-shaped cantilever and the tip protruding from the tip is formed of silicon, and the tip of the cantilever where the tip is formed and the tip are sharpened. A metal film was formed on the silicon surface of the probe thus obtained, and the upper layer of the metal film was covered with an insulating layer except for the sharpened tip and contact hole.

Further, according to another probe for electrochemical AFM of the present invention, a metal wire is inserted into a glass capillary whose tip is sharpened and bent into a hook shape, and the metal wire is exposed at a tip portion and a rear end portion. The metal wire, which is sealed with resin and exposed at the tip, is sharpened to a tip diameter of several hundred nanometers or less.
In addition, in addition to the above-mentioned configuration, another electrochemical AFM probe of the present invention has a flat surface processed on the back surface, and the surface of the surface is coated with a metal thin film to form a mirror surface.

  The method for correcting a mask black defect according to the present invention comprises the steps of: grasping the position of a defective portion of a mask by an atomic force microscope; moving a probe above the defect position; Removing the black defect by an electrochemical reaction with a liquid interposed therebetween, and a step of confirming the defect repair with an atomic force microscope, comprising repairing using a focused ion beam device. Unlike the glass substrate, it does not cause the riverbed phenomenon, the decrease in transmittance, and the charge-up phenomenon on the mask surface. Correction can be performed, and accurate positioning of the corrected portion on the order of nanometers becomes possible.

  According to the method for correcting a mask black defect of the present invention, a step of grasping a position of a defective portion of a mask by an AFM observation function, a step of applying an insulating resist film on a mask surface, and a step of using an AFM probe Scratching; moving the probe of the electrochemical AFM above the defect position; and performing the electrochemical reaction in a state where the probe and the black defect portion of the mask are both electrodes and an electrolytic solution is interposed therebetween. And the step of removing the insulating film on the mask surface, which removes black defects by an electrochemical reaction. Without damaging the glass substrate or normal patterns, and the resist film covers the area other than the defective area, Not to cause an electrochemical reaction in the non-pass. Since the pattern edge from which the defective portion has been removed is finished in a steeply standing form, a photomask with clear pattern boundaries can be provided.

  The mask black defect repairing method of the present invention comprises the steps of: determining the position of a defective portion of a mask by using a scanning microscope; applying an insulating resist film to the mask surface; and irradiating the resist film at the defective portion with a charged particle beam. And moving the probe of the electrochemical AFM above the defect position; and performing the electrochemical reaction in a state where the probe and the black defect portion of the mask are used as both electrodes and an electrolytic solution is interposed therebetween. It consists of a step of removing a defect and a step of removing an insulating film on a mask surface. Since the black defect is removed by an electrochemical reaction, a riverbed phenomenon of processing using a focused ion beam. There is no damage to the glass substrate or normal patterns, and the resist film covers the area other than the defective area, Not to cause an electrochemical reaction in the non-pass. Since the pattern edge from which the defective portion has been removed is finished in a steeply standing form, a photomask with clear pattern boundaries can be provided.

  If the AFM is used as a scanning microscope to obtain defect position information and information is obtained by its observation function, there is no risk of damaging the mask surface as in a scanned image by a charged particle beam, and there is also a problem of charge charging. And the positioning accuracy is high. Further, a scanning ion microscope image can be obtained as necessary by using a focused ion beam for removing the resist, and a scanning electron microscope image can be obtained by using an electron beam for removing the resist.

  The mask black defect repair method of the present invention comprises the steps of: grasping the position of a defective portion of a mask by a scanning microscope function of an FIB apparatus; And removing the remaining black defects by an electrochemical reaction with the probe and the mask black defect portion serving as both electrodes and an electrolytic solution interposed therebetween, and confirming the defect repair with an atomic force microscope It consists of steps. In other words, although the FIB is used in this repair processing, a riverbed cannot be formed by irradiating only the central region of the defect, and all the defects in the portion in contact with the glass substrate surface can be cleaned by being dissolved by an electrochemical reaction. Corrections can be removed. The operation of removing the portion left by the FIB processing without damaging the mask surface by ion irradiation can be performed by the electrolytic processing without burdening the operator as in Patent Document 1. Further, since most of the black defects have been removed by the FIB processing as the first step, the correction processing can be performed in a relatively short correction time.

  In addition, since the tip of the probe of the electrochemical AFM of the present invention is an electrode, a proper close distance between the probe and the mask black defect is measured and set by a function of a tunnel microscope before an electrochemical reaction. It is possible to do.

  In addition, the method for correcting a mask black defect of the present invention, which includes a step of measuring and setting a proper close distance between a probe and a mask black defect by a function of a tunnel microscope before an electrochemical reaction, comprises the steps of: Since an appropriate close distance between the tip of the probe and the surface of the black defect, which is an important requirement for limiting the defect, can be accurately determined by the tunnel current, fine black defects can be finely corrected.

  The mask black defect correcting apparatus of the present invention includes a probe of an atomic force microscope having a tip portion as an electrode, a processing cell for storing an electrolytic solution and a mask as a sample, and a processing cell between the tip portion and the mask surface. And a mechanism for moving the tip of the probe in the X, Y, and Z directions in order to use an observation function as an atomic force microscope. The device used is relatively simple and does not need to be set up in a vacuum chamber, and the work can be performed relatively simply without using a large size.The processing function to remove black mask defects by electrochemical reaction is used. It is possible to provide an apparatus that cleanly corrects a black defect without damaging it.

  The black defect correcting apparatus of the present invention includes an AFM probe having only a tip portion as an electrode, a processing cell for storing an electrolyte and a mask as a sample, and a predetermined gap between the tip portion and the mask surface. The probe comprises a power source for applying a current or a voltage, and a mechanism for moving the position of the tip of the probe in the X, Y, and Z directions. The probe is basically configured only as an electrochemical AFM device. A function of observing the shape of the sample surface by two-dimensional scanning, and a function of moving the probe to the position based on defect position information obtained by the observation, and mechanically removing the resist film on the defect surface, The present invention also has a processing function of removing a mask black defect by an electrochemical reaction using a tip electrode of a probe, and can realize a mask black defect repair method having the above-described effect.

  Also, the position information of the defect area obtained by the observation function is stored, the resist film removal area is determined based on the stored information, and the position of the tip of the probe is set in the X, Y, and Z directions so as to scan the removal area. By providing a computer that issues a drive signal to the mechanism for moving the resist film, the function of mechanically removing the resist film on the defect surface can be easily exhibited.

  An FIB apparatus comprising an FIB column (or an electron beam column) in a vacuum chamber and a sample stage having at least a three-dimensional drive mechanism in a method of covering an area other than the defect area with an insulating resist film so as not to come in contact with the electrolytic solution. (Or an electron beam device), an AFM probe having only the tip portion as an electrode, a processing cell containing an electrolyte and a mask as a sample, and a predetermined current between the tip portion of the probe and the mask surface. Alternatively, a book having a power supply for applying a voltage and a mechanism for moving the position of the probe tip in the X, Y, and Z directions, and having an observation function and a processing function for removing a mask black defect by an electrochemical reaction. When the mask black defect correcting apparatus of the present invention is used, a probe of an atomic force microscope having a fine tip at the tip is used as a probe of the electrochemical AFM, and the tip of the probe and the mask surface are used. Pulse current between Or the fact that a power supply that applies a pulse voltage is combined with a method that covers the area other than the defect area with an insulating resist film and does not come in contact with the electrolytic solution. It can be modified into a photomask with clear boundaries.

  The mask black defect repair apparatus of the present invention includes a FIB apparatus having a SIM function for grasping a defect position and an etching function by beam irradiation, a probe of an atomic force microscope having a tip as an electrode, and an electrolyte and a sample. A processing cell for accommodating the mask, a power source for applying a predetermined current or a predetermined voltage between the probe tip and the mask surface, and a mechanism for moving the position of the probe tip in the X, Y, and Z directions. And a combination with an electrochemical AFM device having a processing function of removing a mask black defect by an electrochemical reaction based on the defect position information obtained by the FIB device. The correction method can be performed smoothly.

  In addition, the mask black defect repairing apparatus of the present invention, which employs a probe in which only the tip portion is formed of a sharp conductive material to form an electrode and the other portion is made of an insulator, employs an electrochemical reaction region. It is effective to narrow down narrowly.

  Further, the power supply connected between the tip of the probe and the mask surface can supply a bias voltage and a pulse of a predetermined current or a predetermined voltage, and has a processing function of removing a mask black defect by an electrochemical reaction. In addition, the mask black defect repairing apparatus of the present invention having the STM function can measure and set an appropriate shortest distance between the probe and the mask black defect, and can perform electric processing by using a pulse to perform electric processing. The chemical reaction region can be effectively narrowed and narrow, and a fine correction process can be performed.

  In addition, by forming the probe from a conductive material and covering the surface with an insulating material so that only the tip is exposed, the mask black defect repair apparatus of the present invention locally limits the electrochemical reaction. The black defect of the fine structure can be corrected cleanly.

  Further, the power supply connected between the tip of the probe and the mask surface is capable of supplying a bias voltage and a pulse of a constant voltage. In addition to a processing function of removing a mask black defect by an electrochemical reaction, a probe is provided. The mask black defect repair apparatus of the present invention having an STM function for measuring and setting an appropriate close distance between the needle and the mask black defect does not require a large structural change, and combines the functions of the AFM and the STM. The mask black defect of the structure can be corrected and processed cleanly.

  The method of manufacturing a probe for an electrochemical AFM according to the present invention includes a step of roughly processing a plate-shaped cantilever portion and a probe portion projecting from the tip thereof from an SOI silicon wafer by dry etching; A step of advancing oxidation from the surface by thermal oxidation to sharpen the tip, a step of coating the surface of the probe and cantilever with a metal thin film, and an insulating layer except for the tip and the contact hole of the probe. Since the method comprises the step of coating, a probe for an electrochemical AFM having a tip diameter of a nanometer order can be provided, whereby the electrochemical reaction region can be locally limited.

  The step of roughly processing the plate-shaped cantilever portion and the probe portion projecting from the tip thereof from the SOI silicon wafer is performed by mask patterning and reactive ion etching, so that a steep columnar body preferable as a probe structure can be formed. Can be formed.

  The method for producing a probe for electrochemical AFM of the present invention includes a step of sharpening a hollow glass capillary in a heated state, a step of heating and cooling the sharpened tip a plurality of times to bend in one direction, and a step of bending the inside of the capillary. Since it consists of a process of inserting a metal wire into the device, a process of sealing both ends of the capillary with resin, and a process of sharpening the tip by electrolytic polishing, it is required as a probe for electrochemical AFM. It is possible to provide a fine electrode facing a sample surface having a tip diameter on the order of nanometers.

  Further, a step of dip coating the probe having undergone the step described in claim 19 in molten apiezon wax, a step of polishing a back surface of the probe to form a mirror surface, and a step of forming a metal thin film around the mirror surface. The method for producing a probe for an electrochemical AFM according to the present invention, comprising a step of performing sputter coating and a step of immersing in chloroform and dissolving an apiezone wax to remove a metal thin film other than a mirror surface, comprises a probe for an AFM. The mirror surface of the required displacement detection mechanism can be formed as a reflection surface only on the specified flat surface, so that the structure can be made simple and no malfunction occurs.

  In the electrochemical AFM probe according to the present invention, the basic structure of the plate-shaped cantilever and the tip protruding from the tip is formed of silicon, and the tip of the cantilever where the tip is formed and the tip are sharpened. A metal coating is formed on the silicon surface of the needle, and the upper layer of the metal coating is covered with an insulating layer except for the sharpened tip and contact hole. Is attached to the electrochemical AFM to correct the mask black defect, the riverbed cannot be formed, the black defect in the fine pattern can be corrected neatly, and the black defect of the mask which does not damage the mask surface by ion irradiation. Allow modification. The probe for an electrochemical AFM of the present invention has a structure in which the tip of the probe is formed of a conductive material and can be connected to an external terminal via a lead contact hole of a metal film, and thus can be used as a probe for a tunnel microscope. can do.

  In addition, since the tip of the probe of the electrochemical AFM of the present invention is an electrode, a proper close distance between the probe and the mask black defect is measured and set by a function of a tunnel microscope before an electrochemical reaction. It is possible to do.

  In the electrochemical AFM probe of the present invention, a metal wire is inserted into a glass capillary whose tip is sharpened and bent into a hook shape, and the metal wire is exposed at the tip and the rear end. The metal wire, which is sealed with resin and exposed at the tip, is sharpened to a diameter of a few hundred nanometers or less. It is possible to realize the removal processing of an extremely local region such as several tens to several hundreds of nanometers. Moreover, since it uses an electrochemical reaction, riverbed cannot be performed unlike the conventional defect correction using a focused ion beam device, and even a black defect in a fine pattern can be corrected neatly. It is possible to correct a black defect of a mask without causing damage by irradiation.

  The present invention has been started with the intention of eliminating various effects caused by ion beam irradiation used for defect correction in the trend of miniaturization of a photomask and short wavelength trend of a light source used for lithography as described above. For that purpose, it is basically sufficient if defect correction without using a focused ion beam can be performed. That is, it is necessary to present a method capable of performing fine processing accurately and efficiently instead of defect correction using a focused ion beam. In other words, it is required that the black defect of the mask be removed relatively quickly and cleanly without damaging the surrounding glass substrate. Therefore, assuming that a conductive material such as chromium is used as the material of the defective portion, the inventors have conceived of removing the conductive material by an electrochemical method. The method of removing defective materials by dissolving them in an electrolytic solution by the electrochemical method does not damage the surrounding glass substrate and can control the reaction rate, so it meets the requirements required in that respect. . However, in the case of using this method, it is important to realize processing for removing only a defective portion having a fine structure. Since the material of the black defect in the mask is also the material of the mask pattern, if the original mask pattern is removed by this electrochemical method, a new white defect will be created and the defect will not be corrected. Considering the current state of photomasks, it is necessary to specify a local region of ten to several hundred nanometers to cause a reaction. In order to realize a local reaction, the fineness, distance and charge amount of the electrode facing the defect are important conditions. Thus, the present invention has conceived of using a probe of a probe microscope as an electrode. The tip is sharpened from several nanometers to several tens of nanometers and a conductive probe is used as an electrode. By positioning this thin electrode at a close distance of 1 to 100 nanometers, a desired local reaction can be realized.

  Patent Document 3 discloses an example in which fine processing is performed using a probe of a probe microscope as an electrode and an electrochemical method. This technique is intended to form a semiconductor mask pattern itself by this method. That is, a conductive cantilever having a conductive probe capable of detecting an atomic force generated between the sample and a workpiece, and a displacement generated by the atomic force between the probe and the sample to be processed are detected. Control means for maintaining a constant distance between the probe and the sample in order to maintain the atomic force at a constant level when scanning the sample to be processed; Between the sample to be processed and the probe, in the presence of a non-polar solvent containing water, This is a fine processing method for performing fine processing on a sample to be processed by applying a voltage to the probe. This document mainly proposes a processing method for removing a surface layer by an electrochemical reaction. However, it is not easy to remove unnecessary regions over the entire mask by this method. The present invention uses this electrochemical technique for correcting black defects on a mask. Moreover, this technique is applied to precision machining of an extremely local area, and a practical technique at that time is presented.

  With reference to FIG. 1, a description will be given of microelectrolytic machining which is the basis of the present invention. In the figure, reference numeral 1 denotes an AFM probe which also serves as a working electrode, 2 denotes a cantilever, and 3 denotes a holder which supports the working electrode. Reference numeral 4 denotes a processing cell in which an electrolytic solution is stored. A sample is placed in this electrolytic solution, and a defect correction process is performed here. Reference numeral 5 denotes an optical displacement detector that detects the amount of displacement of the AFM cantilever, 7 denotes a PZT scanner that drives the machining electrode holder 3 in a three-dimensional (XYZ) direction, and 6 denotes machining via the PZT scanner 7. A Z-axis stage for roughly adjusting the position of the electrode holder 3 in the Z direction, and 8 is a base on which the processing cell 4 is mounted. This processing device basically has a processing function and an observation function, and each operates under the computer 10. In order to perform electrochemical operation as the former processing function, the sample side is used as one electrode, the probe at the tip of the cantilever is used as the other electrode, and the sample is not in contact with the sample in the electrolytic solution of the processing cell 4. The reference electrode 9 in the state is arranged, and the lead wire L1 from the probe electrode, the lead wire L2 from the sample side electrode, and the lead wire L0 from the reference electrode are drawn out and connected to the terminal of the galvanostat 11 for processing. This reference electrode 9 is for detecting a ground potential. The electrochemical reaction does not depend solely on the relative potential difference between the two electrodes, but on the absolute potential of each electrode. In order to measure this absolute potential, a reference electrode 9 is provided. The galvanostat 11 controls an electrochemical reaction with a constant current. Further, the latter observation function includes an AFM controller 12 to which drive position information of the PZT scanner 7 and displacement information of the cantilever 2 detected by the optical displacement detector 5 are input, and controls the operation as the AFM.

  The present invention uses the above apparatus. In the first stage, the drive position information of the PZT scanner 7 and the displacement information of the cantilever 2 detected by the optical displacement detector 5 are obtained, and the observation function as an AFM is used to detect and specify the black defect position on the sample surface. I do. The defect position information obtained from the observation result is stored in the computer 10, and the second-stage black defect correction is executed based on the stored information. First, the driving of the PZT scanner 7 is controlled based on the previous defect position information so that the probe 1 is located at the black defect portion. The galvanostat 11 for processing is operated in a state where the defect region and the tip of the probe 1 are opposed to each other, and a gap between the conductive mask material and the conductive tip opposed via the electrolytic solution. A voltage is applied to cause an electrochemical reaction to dissolve black defects in the electrolyte. The electrolytic solution is not particularly limited, but an acid or an alkali which strongly reacts with the sample is avoided. In the electrochemical processing, since the target is a fine black defect on the mask, the probe 1 serving as the processing electrode has a fine electrode structure, and the distance to the black defect serving as the counter electrode is also an appropriate short distance. is important. Therefore, in the present invention, the entire probe 1 is not made of a conductive material, and only the tip portion is made of a conductive material. Further, the Z-axis stage 6 is controlled so as to be located at an appropriate close distance, and the position of the machining electrode holder 3 in the Z direction is adjusted. In the present invention, a region where an electrochemical reaction is performed by a fine electrode structure (tip diameter of several to several tens of nanometers) and an appropriate close distance (one to several hundred nanometers) is locally (ten to ten to several nanometers). (Several hundred nanometers). As a result, it is possible to realize a fine processing in which only the black defect portions that need to be removed are processed. This reaction is continued until the glass surface is exposed. However, unlike the ion beam processing, even when the glass surface is exposed, the portion does not react, so that the glass substrate is not damaged. As a final third step, it is confirmed whether the correction has been completed by the original observation function of the AFM. This is basically the same as the observation operation in the first stage, but it is to confirm whether the defect found at the beginning is removed by this observation. At that time, it is not always necessary to obtain an image of the entire mask, and the image may be confirmed by local scanning only in the vicinity of the initially detected defect area.

  In addition, the present invention has been started with a view to eliminating various effects caused by ion beam irradiation used for defect correction in the trend of finer photomasks and shorter wavelengths of light sources for lithography as described above. For that purpose, basically, it is only necessary to be able to perform defect correction without using a focused ion beam. However, instead, a method capable of executing fine processing accurately and efficiently must be presented. In other words, it is required that the black defect of the mask be removed relatively quickly and cleanly without damaging the surrounding glass substrate.

  Under such circumstances, the present applicant has conceived of performing a correction to remove black defects by an electrochemical reaction, and in order to cause an electrochemical reaction only in a fine defect portion, an electrode opposed to the defect portion. The use of an atomic force microscope (AFM) probe has been studied. In order to form a finer electrode in the process, the base of the probe is made of an insulator, and only the tip of the probe is made of a conductive material to form a fine electrode. With the black defect part as one electrode, the fine electrode at the tip of the probe is opposed to the optimal close distance via the electrolyte, a predetermined current or voltage is applied, and the black defect is placed in the electrolyte by an electrochemical reaction. Is to dissolve. In this specification, this probe is referred to as a probe for electrochemical AFM. In this series of researches, the applicant of the present invention has proposed a method of removing only black defects by an electrochemical reaction without affecting a normal pattern of a mask to be processed, by using a resist (insulating) film on the entire mask surface. Then, the surface is exposed except for the resist at the defective portion, and a probe for electrochemical AFM is positioned at the position of the defective portion to remove the black defect by an electrochemical reaction. Was obtained. In short, a normal pattern or a region of a glass substrate is protected by being covered with a resist film, and an electrochemical reaction is caused only in a defect portion whose surface is exposed.

  1 shows an embodiment of the present invention. In this embodiment, the AFM function is provided with a function as a scanning tunneling microscope (STM), so that an appropriate close distance between the defect surface and the tip of the probe is measured and the separation distance is easily set. Since the probe of the present invention has an electrochemical action, the tip of the probe 1 is an electrode, and the lead wire L1 to the outside is connected, so that it can be used as it is as an STM. Use configuration. Hereinafter, a method of performing the black defect correction in the present embodiment will be described in chronological order along the flowchart of FIG. FIG. 3 shows a model of a black defect to be corrected. The upper part is a plan view near the black defect, and the lower part is a sectional view thereof. The position of this black defect is detected in step 1 by the normal AFM observation function of two-dimensional scanning. In step 2, the PZT scanner 7 is driven based on the defect position information obtained here to move the probe 1 above the defect position. The probe microscope functioning as the AFM in step 3 is caused to function as the STM. That is, as shown schematically in FIG. 4, a low bias voltage is applied from the power supply 11 'between the mask black defect portion and the electrode at the tip of the probe. A tunnel current flows between the two due to the bias voltage. The Z-axis stage is driven so that the separation distance between the two becomes an appropriate close distance while the tunnel current is measured by the STM control means 12 '. Perform positioning. In step 4, the probe 1 is caused to function as a processing electrode. Therefore, a pulse current (or pulse voltage) is applied from the power supply 11 'between the tip electrode portion of the probe 1 and the mask. In this embodiment, a conductive probe is formed, its surface is coated with an insulating material, and only the tip is exposed. Here, a pulse current (or pulse voltage) is used instead of applying a constant current or a constant voltage using a galvanostat. The reason for this is that when a constant current or a constant voltage is used, there is a gap between the electrode and the electrolyte. When an electric double layer is formed over the entire electrode surface and the electrochemical reaction area is widened, when this pulse current (or pulse voltage) is used, an AC element acts and the electric double layer is formed at the tip. This is because the concentration is concentrated and the electrochemical reaction region becomes narrow. In step 5, a predetermined amount of the mask material in a narrow area centered on the tip of the probe is dissolved in the electrolyte by a predetermined amount in an electrochemical reaction. Incidentally, the electrolytic solution used here is an aqueous solution of NaCl, and this electrochemical reaction is as follows.

Black defect surface _{^{Cr → Cr 2 + + 2e -}} → Cr 3 + + 3e -
Probe side electrode 2H + + 2e ⁻ → H ₂ ↑
FIG. 5 schematically shows the operation mode at this time. That is, a pulsed voltage is applied between the mask and the electrode at the tip of the probe from the pulse power supply 11 ', and a local electrochemical reaction occurs at the defective portion. In step 6, the probe 1 scans the defect area two-dimensionally, and the operations of steps 4 and 5 are repeatedly performed over the entire defect area.

  When one processing at all the points of the defect area is completed, the Z stage 6 is driven by the amount ΔZ corresponding to the thickness of the mask material removed by the single processing in step 7 to displace the probe 1 downward. Then, the defect surface and the position of the probe tip are set again to an appropriate close distance. FIG. 6 schematically shows an operation mode at this time. The Z-axis stage is displaced by ΔZ in the Z direction in response to a command from the control means (AFM controller 12), and the amount of displacement is detected by a displacement detector and fed back to the control means. Note that this position control mechanism is the same for the positioning in the X and Y directions by the PZT scanner 7. In step 8, it is determined whether or not the tip of the probe has reached the glass substrate surface based on the displacement of ΔZ, and if it has not yet reached that position, the process returns to step 4 and the electrochemical processing is repeated. When the tip of the probe reaches the glass substrate, the black defect has already been removed, and the processing is terminated here. In step 9, the sample surface after processing is observed by the AFM function to confirm that the black defect has been corrected and removed. The black defect correcting operation according to the method of the present invention is completed through the above steps.

  Next, the procedure of the black defect repair of the present invention will be described with reference to the flowchart shown in FIG. First, in step 1, the position of a defect on the mask surface is ascertained. A microscope image is obtained by the observation function of the AFM, and positional information of the defective portion is stored. The defect is, for example, a black defect adjacent to a normal pattern as schematically shown in the upper plan view of FIG. In step 2, a resist film is applied to the entire mask surface as shown in the upper side view of FIG. At this time, the resist material needs to be an insulating material. In step 3, as shown in the middle of FIG. 8, the AFM probe is carried to the defect position, scanned corresponding to the defect area, and the resist film in the defect area to be processed is scratched, that is, mechanically scratched and removed. The resulting state is shown in the lower part of FIG. The drive of the sample stage is controlled based on the defect position information of the AFM probe, and the position of the tip of the probe is aligned with the defect. The region to be exposed is preferably slightly smaller than the defect region as schematically shown in the figure. Techniques for removing the resist film include etching using a focused ion beam and electron exposure using an electron beam. In such a case, a focused ion beam apparatus and an electron beam apparatus must be separately prepared. The present invention can process all the steps using only the electrochemical AFM apparatus.

  In Step 4, the defect is corrected and processed by the electrochemical reaction of the electrochemical AFM device in the processing cell containing the electrolytic solution. First, the probe for the electrochemical AFM is driven and controlled above the defect position based on the defect position information. Then, since the surface of the black defect has been exposed in the previous process, the surface of the black defect and the tip of the probe face each other at a short distance via the electrolytic solution as shown in FIG. In order to concentrate the electrochemical reaction locally, the diameter of the counter electrode (the conductive member at the tip of the probe), the distance between the surface of the black defect and the tip of the probe, and the way of applying electric charges are important factors. In the present invention, as a probe for electrochemical AFM, a probe whose base is an insulating member, which has a conductive structure only at the tip, and whose tip is sharpened is used. Further, the distance is measured by detecting a tunnel current in a state in which a bias voltage is applied between both electrodes, and the separation distance is set to an optimum close distance by performing Z-direction control or the like.

The present invention is characterized in that the other region is covered with a resist film in order to cause this electrochemical reaction only at the defective portion. Since this resist film is insulative, no electrochemical reaction occurs at that portion, and a local reaction occurs between the surface of the black defect and the probe tip electrode. In step 5, the separation distance between the two is set to an appropriate close distance, and a pulse current or pulse voltage is applied. Here, the reason why the pulse is used without using the constant current or the constant voltage is that the electric double layer formed on the electrode surface of the probe tip does not spread over the whole but concentrates on the tip portion, thereby narrowing the reaction region. In step 6, the black defect portion is dissolved in the electrolytic solution by an electrochemical reaction. In this case, the dissolution proceeds in a conical shape as shown in FIG. The electrochemical reaction, as described above,
Black defect surface _{^{Cr → Cr 2 + + 2e -}} → Cr 3 + + 3e -
Tip electrode 2H + + 2e ⁻ → H ₂ ↑
Therefore, chromium in the black defect portion is ionized and dissolved in the electrolytic solution, and water is decomposed at the probe side electrode to generate hydrogen gas.

  In step 7, it is checked whether or not the conical hole has reached the glass substrate. If not, the process proceeds to step 8 and the probe is displaced in the Z direction by the depth melted by one pulse processing. Returning to step 5, the operations up to step 6 are repeated. In this case, as shown in the partial view in the lower right circle in FIG. 10, the defective portion melts in a conical shape, and the tip of the conical shape reaches the glass substrate surface by several repeated reactions. Then, melting rapidly proceeds to push open the glass surface at the bottom of the hole, and the edge of the pattern is sharply finished. This phenomenon is a remarkable phenomenon in the method of the present invention in which a resist coating is applied. Finishing the pattern steeply means clearing the boundary as a photomask, which is an extremely preferable phenomenon. Incidentally, when this angle was measured, it was about 85 °. It is understood that the reason why the edge is formed when the resist film is formed is that the normal pattern area is covered with the resist, so that the electrochemical reaction is completely suppressed without contact with the electrolytic solution. You. Since the potential to the defective portion is supplied via the normal pattern, in the case of a large black defect having a large area of the defective portion, it is preferable to start processing from the outer portion not in contact with the normal pattern. This is because supply of electric charge becomes troublesome when a black defect is separated from a normal pattern and becomes an isolated form.

  At the time when the glass substrate is exposed, the correction processing is completed. In step 9, the resist film is removed, and the mask surface is entirely exposed. The processed mask is detected and imaged by detecting the uneven shape by the original AFM function, and it can be confirmed that the black defect has been removed.

  In addition, the present invention has started with an object to remove various effects caused by ion beam irradiation used for defect correction in the trend of miniaturization of a photomask and short wavelength of a light source of lithography as described above. For that purpose, basically, it is only necessary to be able to perform defect correction without using a focused ion beam. However, instead, a method capable of executing fine processing accurately and efficiently must be presented. In other words, it is required that the black defect of the mask be removed relatively quickly and cleanly without damaging the surrounding glass substrate.

  Under such circumstances, the present applicant has conceived of performing a correction to remove black defects by an electrochemical reaction, and in order to cause an electrochemical reaction only in a fine defect portion, an electrode opposed to the defect portion. The use of an atomic force microscope (AFM) probe has been studied. In order to form a finer electrode in the process, the base of the probe is made of an insulator, and only the tip of the probe is made of a conductive material to form a fine electrode. Using the black defect as one electrode, the fine electrode at the tip of the probe is opposed to the optimal close distance via the electrolyte, and a predetermined current or voltage is applied to dissolve the black defect in the electrolyte by electrochemical reaction. It is to let. In this specification, this probe is referred to as a probe for electrochemical AFM. In this series of researches, the applicant of the present invention has proposed a method of removing only black defects by an electrochemical reaction without affecting a normal pattern of a mask to be processed, by using a resist (insulating) film on the entire mask surface. Then, the surface is exposed except for the resist at the defective portion, and a probe for electrochemical AFM is positioned at the position of the defective portion to remove the black defect by an electrochemical reaction. Was obtained. In short, a normal pattern or a region of a glass substrate is protected by being covered with a resist film, and an electrochemical reaction is caused only in a defect portion whose surface is exposed.

  Next, with reference to the flowchart shown in FIG. 11, a description will be given of a modification procedure of the black defect correction of the present invention. First, in step 1, the position of a defect on the mask surface is ascertained. A microscope image is obtained by an observation function of a scanning electron microscope (SEM), a scanning ion microscope (SIM), or a scanning AFM, and positional information of a defective portion is stored. The defect is, for example, a black defect adjacent to a normal pattern as schematically shown in the upper plan view of FIG. In step 2, a resist film is applied to the entire mask surface as shown in the upper side sectional view of FIG. At this time, the resist material needs to be an insulating material. When an electron beam is used, an electron beam resist is used. In step 3, the focused charged particle beam is irradiated as shown in the middle part of FIG. 12, and the resist film in the defect area to be processed is removed as shown in the lower part of FIG. The focused ion beam or electron beam is used as the focused charged particle beam, and the sample stage is driven and controlled for any one of the lens barrels based on the defect position information, and the beam irradiation position is aligned with the defect. I do. The resist film at the defective portion is removed by beam irradiation.If a focused ion beam is used, a method of sputter etching or gas assist etching is used.If an electron beam is used, the resist is exposed to an electron beam and developed and removed. The surface of the black defect is exposed by a gas assisted etching method. The region to be exposed is preferably slightly smaller than the defect region as schematically shown in the figure. The operation at this time is an operation in the vacuum chamber of the charged particle beam device.

  In Step 4, the sample is transferred from the vacuum chamber into the processing cell of the electrochemical AFM apparatus, and the defect is corrected. First, the probe for the electrochemical AFM is driven and controlled above the defect position based on the defect position information. Then, since the surface of the black defect has been exposed in the previous process, the surface of the black defect and the tip of the probe face each other at a short distance via the electrolytic solution as shown in FIG. In order to concentrate the electrochemical reaction locally, the diameter of the counter electrode (the conductive member at the tip of the probe), the distance between the surface of the black defect and the tip of the probe, and the way of applying electric charges are important factors. In the present invention, as a probe for electrochemical AFM, a probe whose base is an insulating member, which has a conductive structure only at the tip, and whose tip is sharpened is used. Further, the distance is measured by detecting a tunnel current in a state in which a bias voltage is applied between both electrodes, and the separation distance is set to an optimum close distance by performing Z-direction control or the like.

  The present invention is characterized in that the other region is covered with a resist film in order to cause this electrochemical reaction only at the defective portion. Since this resist film is insulative, no electrochemical reaction occurs at that portion, and a local reaction occurs between the surface of the black defect and the probe tip electrode. In step 5, the separation distance between the two is set to an appropriate close distance, and a pulse current or pulse voltage is applied. The reason why a pulse is used without using a constant current or a constant voltage is that the electric double layer formed on the surface of the tip electrode of the probe does not spread over the whole but concentrates on the tip, thereby narrowing the reaction region. In step 6, the black defect portion is dissolved in the electrolytic solution by an electrochemical reaction. In this case, the dissolution proceeds in a conical shape as shown in FIG. That is, chromium in the black defect portion is ionized and dissolved in the electrolytic solution, and the probe-side electrode decomposes water to generate hydrogen gas.

  In step 7, it is checked whether or not the conical hole has reached the glass substrate. If not, the process proceeds to step 8 and the probe is displaced in the Z direction by the depth melted by one pulse processing. Returning to step 5, the operations up to step 6 are repeated. In this case, as shown in the partial view in the lower right circle in FIG. 10, the defective portion melts in a conical shape, and the tip of the conical shape reaches the glass substrate surface by several repeated reactions. Then, melting rapidly proceeds to push open the glass surface at the bottom of the hole, and the edge of the pattern is sharply finished. This phenomenon is a remarkable phenomenon in the method of the present invention in which a resist coating is applied. Finishing the pattern steeply means clearing the boundary as a photomask, which is an extremely preferable phenomenon. Incidentally, when this angle was measured, it was about 85 °. It is understood that the reason why the edge is formed when the resist film is formed is that the normal pattern area is covered with the resist, so that the electrochemical reaction is completely suppressed without contact with the electrolytic solution. You. Since the potential to the defective portion is supplied via the normal pattern, in the case of a large black defect having a large area of the defective portion, it is preferable to start processing from the outer portion not in contact with the normal pattern. This is because supply of electric charge becomes troublesome when a black defect is separated from a normal pattern and becomes an isolated form.

  At the time when the glass substrate is exposed, the correction processing is completed. In step 9, the resist film is removed, and the mask surface is entirely exposed. The processed mask is detected and imaged by detecting the uneven shape by the original AFM function, and it can be confirmed that the black defect has been removed.

  In addition, as described above, the present invention aims at eliminating various effects caused by ion beam irradiation used for defect correction in the trend of miniaturization of photomasks and shorter wavelengths of light sources for lithography as described above. Was done. For that purpose, basically, it is only necessary to be able to perform defect correction without using a focused ion beam. However, instead, a method capable of executing fine processing accurately and efficiently must be presented. In other words, it is required that the black defect of the mask be removed relatively quickly and cleanly without damaging the surrounding glass substrate. Therefore, assuming that a conductive material such as chromium is used as the material of the defective portion, the inventors have conceived of removing the conductive material by an electrochemical method. The reaction of dissolving the defective material in the electrolytic solution by the electrochemical method does not damage the surrounding glass substrate, so it satisfies the requirements required in that respect, but the problem is the fine structure The purpose of this method is to remove only the defective portion. Since the material of the black defect in the mask is also the material of the mask pattern, if the original mask pattern is removed by this electrochemical method, a new white defect will be created and the defect will not be corrected. Considering the current state of photomasks, it is necessary to specify a local region of ten to several hundred nanometers to cause a reaction. In order to realize a local reaction, structural conditions such as the fineness and distance of an electrode facing a defect and the amount of charge given between the two electrodes are important conditions. Thus, the present invention has conceived of using a probe of a probe microscope as an electrode. It is intended to use a probe whose tip is sharpened to several to several tens of nanometers and made conductive. By positioning this thin electrode at a close distance of 1 to 100 nanometers, a desired local reaction can be realized.

  The black defect repairing process using this electrochemical reaction does not cause the riverbed phenomenon, and enables fine processing of fine structures by adopting the above-mentioned structure as an AFM probe. However, there is a disadvantage that the time required for the correction processing is longer than that of the conventional method using the FIB apparatus. Therefore, in the present invention, it has been conceived that processing of a region where the riverbed phenomenon does not occur is performed by etching using FIB, and only processing of the remaining portion is performed by this electrochemical reaction. This is the same as Patent Document 1 in that a region where the riverbed phenomenon does not occur is processed by FIB etching. In view of the fact that the riverbed phenomenon is caused by the fact that the ions irradiated on the defective portion hit the glass substrate surface in the vicinity where the ions were repelled, or that the ion beam has a normal distribution and its skirt hits the nearby glass substrate surface, the defect By processing only the central portion excluding the peripheral edge of the region, the occurrence of the riverbed phenomenon can be avoided. This idea is the same as in the above-mentioned document 1, but in the present invention, the center portion to be processed is also left near the glass substrate. This is because if the surface of the glass substrate is etched by FIB, the glass substrate is inevitably damaged. Defects left by the FIB processing including this part are removed by an electrochemical reaction. Since most of the black defects have already been removed by the FIB processing, the time required for this processing is not so long.

  In the following correction processing method of the present invention, first, a FIB apparatus is used as a first step, a microscope image of a mask is obtained, defect position information is fetched and stored, and the FIB apparatus removes the center of the defect area except for the peripheral edge. Most of the parts are etched. Thereafter, as a second stage, the remaining black defects are electrochemically electrolytically treated using the apparatus shown in FIG. Next, the procedure of the black defect repair will be described with reference to the flowchart shown in FIG. First, in step 1, the position of a defect on the mask surface is ascertained. A microscope image is obtained by an observation function of a scanning ion microscope (SIM), and positional information of a defective portion is stored. The defect is, for example, a black defect adjacent to a normal pattern as schematically shown in the upper plan view and the side sectional view of FIG. In step 2, as shown in the middle part of FIG. 14, a focused ion beam (FIB) is irradiated to the defect region to remove black defects by etching. In this case, it is important that the irradiation area avoids the peripheral edge of the defect area and also leaves the vicinity of the glass substrate in the center area of the defect to be irradiated so as not to be etched. The reason why the peripheral portion is not irradiated with the FIB is to avoid the riverbed phenomenon, and the reason that the portion near the glass substrate is left is to prevent the FIB from being damaged by the FIB. As an etching technique, sputter etching or gas assisted etching can be used. The above operation is the first stage process performed by the FIB device.

  In step 3, the mask, which is a sample to be processed, is transferred to an electrolytic processing apparatus (hereinafter, referred to as an electrochemical AFM apparatus) for performing processing by an electrochemical reaction, and the subsequent second stage processing is executed. In step 3, as shown in the lower part of FIG. 14, the tip of the electrochemical AFM tip is moved to the XY two-dimensional position of the periphery of the remaining black defect without performing FIB irradiation in the previous step 2. This position is positioned farthest from a normal pattern. This is because supply of electric charge becomes difficult when this portion becomes an isolated region by processing. Since the separation distance between the black defect and the probe tip electrode when performing the electrolytic processing affects the region in which the electrochemical reaction occurs, it is important to set an appropriate close distance. In step 4, an appropriate close distance is set. In the present invention, it is appropriate to set a position in the Z direction while measuring a tunnel current by applying a bias voltage between the two. In step 5, a predetermined current or a predetermined voltage pulse is applied between the two positions, and the remaining black defects are dissolved in the electrolytic solution by an electrochemical reaction. The reason why a pulse is used without using a constant current or a constant voltage is that the electric double layer formed on the surface of the tip electrode of the probe does not spread over the whole but concentrates on the tip, thereby narrowing the reaction region. Electrolytic processing of the black defect left in step 6 is performed, and chromium in the black defect portion is ionized and dissolved in the electrolytic solution, and water is decomposed at the probe side electrode to generate hydrogen gas. If the defect area is large, steps 5 and 6 are repeated while driving the PZT scanner 7 to raster-scan the probe 1 in the XY directions in a direction gradually approaching the normal pattern.

  In step 7, it is checked whether the black defect has been removed and the glass substrate has been reached. If not, the process proceeds to step 8 and the probe is displaced in the Z direction by the depth melted by one pulse processing. Returning to step 5, the operations up to step 6 are repeated. In the melting mode at this time, the peripheral portion of the defect region melts in a V-shape, and the V-shaped tip reaches the glass substrate surface by several repeated reactions. The black defect left at the bottom of the center hole rapidly dissolves so as to push open the glass surface when the layer is as thin as several nm, but when a certain thickness remains, the probe 1 is raster-shaped. Dissolves in the process of scanning. FIG. 15 schematically shows where the black defect is dissolved and disappears cleanly. In step 9, as the third step, the observation function of the AFM is used to scan the mask surface to take a surface shape image and confirm that the black defect has been corrected and removed. Thus, a series of operations according to the present invention is completed.

  The FIB apparatus for performing the first step is an apparatus for performing the defect repair method of the present invention, but there is basically no significant difference from the conventional FIB apparatus for mask repair. However, based on the defect position information grasped by this apparatus, the FIB is irradiated so as to avoid the periphery of the defect area, and the central part of the defect to be irradiated is operated so that the vicinity of the glass substrate is not etched. It is necessary to have a function to transmit information to the electrochemical AFM device that performs the second stage operation. The former can be dealt with by preparing software for executing an indexing operation and a drive control based on the result, and the latter can be controlled by providing an export / import function between the control unit of the FIB device and the electrochemical AFM device. This can be handled by using a personal computer form common to both devices as a unit.

  As for the electrochemical AFM device for performing the second stage operation, as a basic configuration, an AFM probe having a tip portion as an electrode, a processing cell for storing an electrolyte and a mask as a sample, the probe tip portion and a mask A power supply for applying a predetermined current or a predetermined voltage between the probe and a surface; and a mechanism for moving the position of the tip of the probe in X, Y, and Z directions, and a mask based on defect position information obtained by the FIB apparatus. It is necessary to have a processing function to remove black defects by an electrochemical reaction. Then, in order to realize fine electrolytic processing, an AFM probe having only a tip portion formed of a sharp conductive material as an electrode and an other portion formed of an insulator is used. In such a probe structure, the probe is formed of a conductive material, and the tip other than the tip is covered with an insulator, or a thin conductive wire is inserted into an insulating capillary to expose the tip and sharpen the tip. It can be produced by a technique.

  The power supply connected between the tip of the probe and the mask surface is capable of supplying a bias voltage and a pulse of a constant current or a constant voltage. By measuring the tunnel current generated therebetween, it becomes possible to measure and set an appropriate short distance when an electrochemical reaction occurs. An STM function can be provided in addition to the AFM function. In addition, by providing a function of supplying a pulse of a predetermined current or a predetermined voltage, the electrochemical reaction region can be locally limited as described above.

  Now, as described above, the applicant of the present application has studied to eliminate various effects caused by ion beam irradiation used for defect correction in the trend of finer photomasks and shorter wavelengths of light sources for lithography. Has been advanced. Assuming that a conductive material such as chromium is used as the material of the defective portion, the inventors have conceived of removing the conductive material by an electrochemical method. The purpose of this invention is to realize a process for removing only a defective portion which is a microstructure. Considering the current state of photomasks, it is necessary to specify a local region of ten to several hundred nanometers to cause a reaction. In order to cause the electrochemical reaction to be locally restricted, the fineness and distance of the electrode facing the defect and the amount of charge are important conditions. In order to realize a local reaction that does not affect a normal mask pattern, it is necessary to insulate the tip of the probe of a sharp probe microscope other than the tip of the tip. In other words, the present invention described below is a technical idea of how to reduce the exposed area of the probe tip serving as the counter electrode and achieve sharpening.

  This electrolytic processing uses the above-described apparatus, and obtains the driving position information of the PZT scanner 7 and the displacement information of the cantilever 2 detected by the optical displacement detector 5 as a first step, and performs an observation function as an AFM on the sample surface. The position of the black defect is detected and specified. Defect position information obtained from this observation result is sent from the observation computer to the processing computer, and black defect correction is executed as a second step. First, the driving of the PZT scanner 7 is controlled based on the previous defect position information so that the probe 1 is located at the black defect portion. The galvanostat 11 for processing is operated in a state where the defect region and the tip of the probe 1 are opposed to each other, and a gap between the conductive mask material and the conductive tip opposed via the electrolytic solution. A voltage is applied to cause an electrochemical reaction to dissolve black defects in the electrolyte. The electrolytic solution is not particularly limited, but an acid or an alkali which strongly reacts with the sample is avoided. In the electrochemical processing, since the target is a fine black defect on the mask, the probe 1 serving as the processing electrode has a fine electrode structure, and the distance to the black defect serving as the counter electrode is also an appropriate short distance. It becomes important. The Z-axis stage 6 is controlled so as to be located at an appropriate close distance, and the Z-direction position of the machining electrode holder 3 is adjusted. In the present invention, a region where an electrochemical reaction is performed by a fine electrode structure (tip diameter of several to several tens of nanometers) and an appropriate close distance (one to several hundred nanometers) is locally (ten to ten to several nanometers). (Several hundred nanometers). As a result, it is possible to realize a fine processing in which only the black defect portions that need to be removed are processed. This reaction is continued until the glass surface is exposed. Unlike the ion beam processing, even if the glass surface is exposed, the portion does not react, so that the glass substrate is not damaged. As a final third step, it is confirmed whether the correction has been completed by the original observation function of the AFM. This is basically the same as the first-stage observation operation. This observation confirms that the defects initially found have been removed by this observation.

  Next, a method of manufacturing a probe for an electrochemical AFM according to the present invention will be described according to the procedure with reference to a flowchart shown in FIG.

  Step 1: As a material, an SOI wafer substrate in which an insulating layer is sandwiched in the center and an upper and lower silicon layer is sandwiched is used, and its surface is subjected to mask patterning with silicon dioxide (SiO 2) as shown in FIG.

  Step 2: Dry etching is performed on the silicon substrate that has not been covered with the mask by reactive ion etching (RIE) using plasma ions on the silicon substrate on which the mask patterning has been performed. Since this processing is RIE using SF6 gas, etching proceeds in the depth direction of the silicon layer, and at the same time, the lower portion of the mask is also under-etched. As a result, the mask is covered with the mask as shown in FIG. The remaining silicon is left in a steep columnar shape. In the present invention, this portion is referred to as a probe portion, and a portion etched into a wide thin layer is referred to as a cantilever. In this step, the basic structure is roughly machined.

Step 3: When the dry etching process is completed, the SiO ₂ mask is removed as shown in FIG. This is done with normal chemical treatments.

Step 4: Next, the thermally processed silicon is subjected to a thermal oxidation treatment. As shown in FIG. 17D, while the silicon is heated, the silicon gradually oxidizes into SiO ₂ from the surface, but the silicon region which is not oxidized at the probe portion protruding into a columnar shape has a core region. It narrows into a part, and its tip part remains sharpened. This sharpening realizes the formation of a tip having a nanometer-order tip diameter required as a probe for an electrochemical AFM, and is an important point of the present invention.

  Step 5: Subsequently, when the oxidized silicon layer is removed by a chemical treatment, the silicon left in the core portion appears as a sharpened probe as shown in FIG.

Step 6: A large number of silicon probes to be processed are formed in a matrix array on a silicon wafer, and the individual silicon probes formed in this step are separated and processed. This processing is a conventional method of coating the resist film, exposing it to light, and removing the silicon at the boundary portion by etching, and is separated independently on the insulating layer SiO ₂ as shown in FIG. Through the above steps, the processing of the silicon which is the basic structure of the probe is completed.

  Next, an electrode structure at the tip of the probe necessary as a probe for electrochemical AFM and a lead structure for supplying electric charges to the electrode are formed.

Step 7: First, as shown in FIG. 17g, a resist is applied to the boundary between the independently separated silicon probes where the insulating layer SiO ₂ is exposed.

  Step 8: A metal coating is applied to the silicon surface including the probe with the periphery of each probe surrounded by the resist. For example, platinum Pt is used as a metal material. However, since it has poor affinity with silicon, first, a thin titanium film is coated as an S8A underlayer, and a platinum Pt thin film suitable as an S8B electrode material or a lead member is formed thereon. Coating. The state of the probe at this time is such that the metal is coated on both the silicon surface exposed on the surface and the resist surface as shown in the sectional view of FIG.

  Step 9: When the resist material around each probe is removed at the stage where the metal thin film has been coated, as shown in FIG. It has become.

Step 10: A SiO ₂ thin film as an insulating film is formed on the entire surface of the probe in this state by a chemical vapor deposition (CVD) technique. The state at this time is shown in a sectional view in FIG.

  Step 11: Subsequent to formation of the insulating film, a resist film is applied on the upper layer, and patterning is performed for forming a contact hole near the end opposite to the partial probe serving as a cantilever. This contact hole is a hole for connecting a power supply lead to the tip of the probe serving as an electrode of the electrochemical AFM and an external terminal. The state at this time is shown by k in FIG.

Step 12: In order to realize a structure in which only a small area at the tip of the probe is exposed as a metal electrode, first, the resist film covering the tip of the probe is exposed to O ₂ plasma as shown in FIG. To remove.

Step 13: Following the removal of the resist film at the tip of the probe, the insulating film SiO ₂ in the region of the tip and the contact hole is removed by fluorocarbon (CF ₄ or C ₂ F ₆ ) plasma. The configuration at this time is shown in FIG.

  Step 14: After removing the resist covering the probe as the uppermost layer, the probe is entirely covered with the insulating layer as shown in FIG. 18n, and the tip of the probe and the contact hole are removed. Only the region has the insulating layer removed and the metal thin film is exposed. The above is the step of forming the microelectrode at the tip of the probe as the electrochemical AFM probe.

  Step 15: Finally, in order to form the back surface of the probe, unnecessary portions of the silicon layer and the insulating layer on the back surface are removed. For this purpose, first, a mask as shown by O in FIG. 18 is formed for silicon etching.

  Step 16: Following formation of the mask, unnecessary portions of silicon are removed by alkali etching on the back surface. The silicon is left by the mask in the boundary area between the rear end of the cantilever, which is the holding section when the probe is attached to the AFM, on the opposite side to the probe section, and the adjacent independent probe. The configuration at this time is shown in p of FIG.

Step 17: Next, etching using hydrofluoric acid is performed to remove the insulating layer SiO ₂ . The insulating layer SiO ₂ is a buried oxide film of an SOI wafer substrate, which is a material, and individual probes are separated separately by removing the insulating film. The probe manufactured in the above steps is shown in q of FIG. On the probe side surface, the conductive material is exposed only at the sharpened probe tip and the contact hole provided at the base of the cantilever, the other is covered with an insulating material, and the silicon layer on the back surface It is in an exposed state.

  AFM probes generally form a mirror on the back of the cantilever to detect displacement. Since this probe is not only used for the electrochemical reaction but also has a function as a normal AFM, it is preferable to form a mirror in terms of displacement detection. However, it is not preferable to arrange a metal film near the probe in order to locally limit the electrochemical reaction region. Therefore, in the case of the present invention, the silicon surface is used as a mirror surface without forming a metal mirror surface on the back surface of the cantilever near the probe.

Next, the above-mentioned modified manufacturing method is shown in FIG. 19 as a method for manufacturing a probe for an electrochemical AFM of the present invention. The steps from step 1 to the patterning of the mask to the formation of the insulating film in step 10 are the same as those shown in the flowchart of FIG. Step 11 is a flowchart of FIG. 16 in that the removal of the insulating film at the tip portion of the probe and the contact hole region is performed by sputter etching or gas-assisted etching using a focused ion beam (FIB) apparatus without using plasma etching. Is different from That is irradiated while scanning the S11AFIB the pattern area of the contact hole to remove the insulating layer of SiO ₂ that portion. Thereafter, the tip of the S11B probe is irradiated with an ion beam to remove the insulating layer SiO ₂ at that portion. Then, the operation from step 15 onward in FIG. 16 is executed on and after step 12 to produce a probe for an electrochemical AFM of the present invention.

  With reference to FIG. 20, a description will be given of the black defect correction processing by the apparatus using the electrochemical AFM probe manufactured in this manner. A model of a black defect to be corrected is shown in a plan view and a sectional view in the upper part of FIG. This is a form in which a pattern material such as chromium is attached to a glass substrate adjacent to a normal pattern. The position of this black defect is detected in step 1 by the normal AFM observation function of two-dimensional scanning. In step 2, the PZT scanner 7 is driven based on the defect position information obtained here to move the probe 1 above the defect position. This state is shown in the middle part of FIG. In step 3, the Z-axis stage is driven to position the probe 1 such that the distance between the tip of the probe 1 and the sample surface is set to an appropriate close distance. For example, a probe microscope functioning as an AFM is caused to function as an STM. That is, while measuring the tunnel current flowing between the tip portion of the probe 1 and the sample surface, the Z-axis stage is driven so that the distance between the two becomes an appropriate close distance, thereby positioning the probe 1. In step 4, the probe 1 is caused to function as a processing electrode. Therefore, a predetermined current or voltage is applied from the power supply 11 ′ between the tip electrode portion of the probe 1 and the mask. In step 5, a predetermined amount of the mask material in a narrow area around the tip of the probe is dissolved in the electrolytic solution by an electrochemical reaction by a predetermined amount. That is, for example, a pulsed current or voltage is applied between the mask and the electrode at the tip of the probe from the power supply 11 ', and a local electrochemical reaction occurs at the defective portion. In step 6, the probe 1 is scanned, and the operations in steps 4 and 5 are executed at each point in all the defect areas.

  When one processing at all the points of the defect area is completed, the Z stage 6 is driven by the amount ΔZ corresponding to the thickness of the mask material removed by the single processing in step 7 to displace the probe 1 downward. Then, the defect surface and the position of the probe tip are set again to an appropriate close distance. The operation mode at this time, that is, the probe scanning is schematically shown in the lower part of FIG. The Z-axis stage is displaced by ΔZ in the Z direction in response to a command from the control means (AFM controller 12), and the amount of displacement is detected by a displacement detector and fed back to the control means. Note that this position control mechanism is the same for the positioning in the X and Y directions by the PZT scanner 7. In step 8, it is determined whether or not the tip of the probe has reached the glass substrate surface by the displacement of ΔZ. If the tip of the probe has not yet reached that position, return to step 4 and repeat the electrochemical machining. When the tip of the probe reaches the glass substrate, the black defect has already been removed, and the processing is terminated here. In step 9, the sample surface after processing is observed by the AFM function to confirm that the black defect has been corrected and removed. The black defect correcting operation according to the method of the present invention is completed through the above steps.

  In addition, as described above, the applicant of the present invention has studied to eliminate various effects caused by ion beam irradiation used for defect repair in the trend of finer photomasks and shorter wavelengths of light sources for lithography. did. Assuming that a conductive material such as chromium oxide is assumed as the material of the defective portion, the inventors have conceived of removing the material by an electrochemical method. The purpose of this invention is to realize a process for removing only a defective portion which is a microstructure. Considering the current state of photomasks, it is necessary to specify a local region of ten to several hundred nanometers to cause a reaction. In order to cause the electrochemical reaction to be locally limited, the fineness, distance, and charge amount of the electrode facing the defect are important conditions, and local reactions that do not affect the normal mask pattern In order to realize the above, it is necessary to further sharpen the tip of a sharp probe microscope. That is, the present invention is a technical idea of how to realize the sharpening of the tip of the probe serving as the counter electrode.

  The following electrolytic processing uses the above-mentioned apparatus, and obtains the drive position information of the PZT scanner 7 and the displacement information of the cantilever 2 detected by the optical displacement detector 5 as a first step, and uses the observation function as an AFM to obtain the sample surface. The upper black defect position is detected and specified. The defect position information obtained from the observation result is stored in the storage means in the computer 10, and the second-stage black defect correction is executed based on the stored information. First, the driving of the PZT scanner 7 is controlled based on the previous defect position information so that the probe 1 is located at the black defect portion. The galvanostat 11 for processing is operated in a state where the defect region and the tip of the probe 1 are opposed to each other, and a gap between the conductive mask material and the conductive tip opposed via the electrolytic solution. A voltage is applied to cause an electrochemical reaction to dissolve black defects in the electrolyte. The electrolytic solution is not particularly limited, but an acid or an alkali which strongly reacts with the sample is avoided. In the electrochemical processing, since the target is a fine black defect on the mask, the probe 1 serving as the processing electrode has a fine electrode structure, and the distance to the black defect serving as the counter electrode is also an appropriate short distance. It becomes important. The Z-axis stage 6 is controlled so as to be located at an appropriate close distance, and the Z-direction position of the machining electrode holder 3 is adjusted. In the present invention, an area where an electrochemical reaction is caused by a fine electrode structure (tip diameter of several to several tens of nanometers) and an appropriate close distance (one to several hundred nanometers) is locally (ten to ten to several nanometers). (Several hundred nanometers). As a result, it is possible to realize a fine processing in which only the black defect portions that need to be removed are processed. This reaction is continued until the glass surface is exposed. However, unlike the ion beam processing, even when the glass surface is exposed, the portion does not react, so that the glass substrate is not damaged. As a final third step, it is confirmed whether the correction has been completed by the original observation function of the AFM. This is basically the same as the observation operation in the first stage, but it is to confirm whether the defect found at the beginning is removed by this observation. At that time, it is not always necessary to obtain an image of the entire mask, and the image may be confirmed by local scanning only in the vicinity of the initially detected defect area.

  Next, a method for producing a probe for an electrochemical AFM of the present invention, which is different from the above, will be described according to the procedure.

  Step 1. A metal wire of φ50 μm such as tungsten: W or platinum: Pt is reduced in diameter by electrolytic polishing and processed to about φ10 μm in advance.

  Step 2. A hollow glass capillary (φout is 120 μm and φin is 75 μm) as shown in FIG. 21A is irradiated with a laser as shown in FIG. To obtain two sharpened glass capillaries. The right side of the figure shows a sketch of a microscope image. The original photomicrograph was sketched because it was not halftone if it was a binary image. The lower part is an enlarged view of the tip.

  Step 3. Heating and cooling are repeated by irradiating a laser beam from one side to the tip of the glass capillary thus obtained as shown in FIG. This causes the tip of the glass capillary to be bent in one direction as shown in FIG. The microscope image sketch is shown on the right. The sharpened tip serves as a probe and the straight tube serves as a cantilever, and constitutes an AFM probe.

  Step 4. As shown in FIG. 23, the metal wire prepared and prepared in the step 1 is passed through a glass capillary having a sharpened tip with a bent shape.

  Step 5. With the metal wire inserted into the glass capillary, the tip and the end of the glass capillary are sealed with an epoxy resin.

  Step 6. After the sealing step, the tip of the probe is electrolytically polished, and the exposed end of the metal wire is sharpened. A microscope image sketch of the tip is shown in the upper part of FIG. The exposed tip of the metal serves as a counter electrode during the electrochemical reaction.

  The above-described steps are for producing a configuration as a probe of the AFM having an electrochemical processing function according to the present invention. Subsequently, a mirror is formed on the back surface of the cantilever in order to provide an AFM original displacement detection function. The method will be described step by step.

  Step 7. The glass probe that has been subjected to step 6 is immersed in a molten Apiezon wax to perform dip coating.

  Step 8. A part of the back surface of the probe which becomes the cantilever to which the dip coating is applied is mechanically polished to form a flat mirror surface. By this processing, the coating of the Apiezon wax is removed only in this portion. The state at this time is illustrated on the left side of FIG. 24, and a microscope image sketch of the rear surface of the probe on which a mirror surface is formed is illustrated on the right side. The lower part is a partially enlarged view.

  Step 9. A thin film of titanium Ti (t75 nm) / gold Au (t50 nm) is formed by sputtering around a flat mirror surface on the back surface of the probe, and the mirror surface is coated. The microscope image sketch at that time is shown in the upper right part of FIG.

  Step 10. The probe after step 9 is immersed in a chloroform solution to dissolve the apiezone wax. By this processing, the thin film sputtered on the surface other than the mirror surface can be removed together with the apiezone wax. This is to prevent the laser light from being reflected in an area other than the flat mirror surface, which may cause noise in optical displacement detection. A microscope image sketch of the probe subjected to this processing is shown in the lower right part of FIG.

  Note that a processing method similar to the above Steps 2 and 3 and Steps 8 and 9 is also disclosed in Patent Document 2 “Scanning Near-Field Atomic Force Microscope, Probe Used in the Microscope, and Probe Manufacturing Method”. This is basically to have both the function of the AFM and the function of an optical near-field microscope. The glass material used for the probe is not a capillary as in the present invention, but a core and a cladding. It is an optical fiber consisting of, similar to the method of sharpening the rod-shaped glass material and bending the tip, and the process for forming a mirror surface on the back of the cantilever as a function as an AFM is only partially similar. belongs to.

  Through the above steps, a probe for an electrochemical AFM according to the present invention as shown in FIG. 26 is manufactured. The tip portion of the glass capillary is bent into a hook shape and sharpened, and this portion serves as a probe portion of a probe microscope, and the straight tube portion of the glass capillary serves as a cantilever portion. A fine metal wire such as platinum is penetrated into the capillary, and the tip diameter of the thin metal wire exposed on the probe side is sharpened to the order of nanometers to form the tip portion of the probe. The base of the probe is made of glass, which is an insulating material, and the exposed tip of this thin metal wire is the tip of the probe, so an extremely small electrode can be formed and the electrochemical reaction can be locally performed. It is effective in getting up. The probe for electrochemical AFM according to the present invention has an electrochemical processing function in addition to an observation function and a distance detection function as an AFM or a scanning tunneling microscope (STM). In other words, the tip can receive the interatomic force acting between it and the sample surface to detect the shape of the sample surface, and a bias voltage is applied between the tip facing the sample surface at a close distance. The distance between the two can be accurately detected from the tunnel current flowing through the electrode, and the electrode acts as an electrode for electrolytic processing by applying a voltage with the electrolyte interposed between the sample surface and this tip. It can cause an electrochemical reaction in a limited manner.

  In addition, a mirror surface is formed on the back surface of the glass capillary straight tube portion serving as a cantilever, and constitutes a part of a displacement detection mechanism as an AFM.

  With reference to FIG. 27, a description will be given of the black defect correction processing by the apparatus using the electrochemical AFM probe manufactured as described above. The upper part of FIG. 27 shows a model of a black defect to be corrected in a plan view and a sectional view. This is a mode in which a pattern material such as Cr adheres to a glass substrate adjacent to a normal pattern. The position of this black defect is detected in step 1 by the normal AFM observation function of two-dimensional scanning. In step 2, the PZT scanner 7 is driven based on the defect position information obtained here to move the probe 1 above the defect position. This state is shown in the middle part of FIG. In step 3, the Z-axis stage is driven to position the probe 1 such that the distance between the tip of the probe 1 and the sample surface is set to an appropriate close distance. For example, while the probe microscope functioning as the AFM functions as the STM, the tunnel current flowing between the two is measured, and the Z-axis stage is driven so that the separation distance between the two becomes an appropriate close distance, thereby positioning the probe 1. I do. In step 4, the probe 1 is caused to function as a processing electrode. Therefore, a predetermined current or voltage is applied from the power supply 11 ′ between the tip electrode portion of the probe 1 and the mask. In step 5, a predetermined amount of the mask material in a narrow area around the tip of the probe is dissolved in the electrolytic solution by an electrochemical reaction by a predetermined amount. That is, for example, a pulsed current or voltage is applied between the mask and the electrode at the tip of the probe from the power supply 11 ', and a local electrochemical reaction occurs at the defective portion. In step 6, the probe 1 is scanned, and the operations in steps 4 and 5 are executed at each point in all the defect areas.

  When one processing at all the points of the defect area is completed, the Z stage 6 is driven by the amount ΔZ corresponding to the thickness of the mask material removed by the single processing in step 7 to displace the probe 1 downward. Then, the defect surface and the position of the probe tip are set again to an appropriate close distance. The operation mode at this time, that is, the probe scanning is schematically shown in the lower part of FIG. The Z-axis stage is displaced by ΔZ in the Z direction in response to a command from the control means (AFM controller 12), and the amount of displacement is detected by a displacement detector and fed back to the control means. Note that this position control mechanism is the same for the positioning in the X and Y directions by the PZT scanner 7. In step 8, it is determined whether or not the tip of the probe has reached the glass substrate surface based on the displacement of ΔZ, and if it has not yet reached that position, the process returns to step 4 and the electrochemical processing is repeated. When the tip of the probe reaches the glass substrate, the black defect has already been removed, and the processing is terminated here. In step 9, the sample surface after processing is observed by the AFM function to confirm that the black defect has been corrected and removed. The black defect correcting operation according to the method of the present invention is completed through the above steps.

FIG. 1 is a diagram showing a basic configuration of an apparatus for executing a method of correcting a mask black defect according to the present invention. 5 is a flowchart illustrating an operation of the embodiment of the present invention. FIG. 3 is a diagram illustrating a structure of a mask black defect that is an object of the present invention. FIG. 4 is a diagram showing a mode in which the apparatus of the present invention measures a distance between a tip of a probe and a black defect by an STM function. FIG. 3 is a view showing a mode in which the apparatus of the present invention causes an electrochemical reaction in which a probe tip portion and a black defect serve as both electrodes. It is a figure explaining the mechanism which moves a probe in X, Y, and Z directions in correction processing of the present invention. 5 is a flowchart illustrating an operation of the embodiment of the present invention. The top plan view is a diagram illustrating the structure of the mask black defect that is the subject of the present invention, the top cross-sectional view is a diagram showing a state where a resist film is applied, and the middle stage is a state where the resist film on the surface of the defect is scratched by a probe The lower part is a view showing a state where the resist film at the defective portion is removed. It is a figure which shows the form which positions an electrode for electrochemical AFM above a black defect position, and causes an electrochemical reaction. FIG. 4 is a view showing a form in which the defect portion is dissolved by an electrochemical reaction in which the probe tip and the black defect become both electrodes in the apparatus of the present invention. 5 is a flowchart illustrating the operation of the present invention. The upper plan view is a diagram illustrating the structure of a mask black defect that is an object of the present invention, the upper cross-sectional view is a diagram illustrating a state in which a resist film is applied, and the middle diagram is a diagram illustrating a state in which a defect is irradiated with a charged particle beam. The lower part is a view showing a state where the resist film at the defective portion is removed. 5 is a flowchart illustrating an operation of the embodiment of the present invention. FIG. 3 is a diagram illustrating a structure of a mask black defect that is an object of the present invention and a repair form thereof. It is a figure showing the state where the black defect was removed by processing by the tip for electrochemical AFM of the present invention. 4 is a flowchart illustrating a process for producing a probe for an electrochemical AFM of the present invention. It is a figure which shows the form in each process of the first half which produces the probe for electrochemical AFM of this invention. It is a figure which shows the form in each process of the latter half of producing the probe for electrochemical AFM of this invention. 5 is a flowchart illustrating another embodiment of a process for producing a probe for an electrochemical AFM of the present invention. It is a figure explaining black defect correction processing by a micro electrolytic processing device using a probe for electrochemical AFM of the present invention. FIG. 3 is a diagram showing a sharpened form of a glass capillary as a material of the probe of the present invention. It is a figure which shows the bending process form of a glass capillary. It is a figure explaining the form which inserts a metal wire in a glass capillary. FIG. 3 is a diagram illustrating a form in which a plane serving as a mirror surface of a probe is formed. FIG. 3 is a diagram illustrating an embodiment in which a mirror surface of a probe is coated with a metal thin film. FIG. 3 shows a completed probe for an electrochemical AFM of the present invention. It is a figure explaining black defect correction processing by an electrolytic processing device using a probe for electrochemical AFM of the present invention.

Explanation of reference numerals

Reference Signs List 1 AFM probe 2 Cantilever 3 Processing electrode support holder 4 Processing cell 5 Optical displacement detector 6 Z-axis stage 7 PZT scanner 8 Base 9 on which processing cell 4 is mounted 9 Reference electrode 10 Computer 11 Processing 12 AFM controller 12
L1 Lead wire from probe electrode L2 Lead wire from sample side electrode L0 Lead wire from reference electrode

Claims (23)

  Grasping the black defect portion position of the mask by an atomic force microscope; moving the probe of the atomic force microscope above the black defect position; and using the probe and the mask black defect portion as both electrodes. A method for correcting a mask black defect, comprising the steps of: removing the black defect by an electrochemical reaction with an electrolyte interposed; and confirming the removal of the black defect by the atomic force microscope.   Grasping the position of the defective portion of the mask by the observation function of the AFM, applying an insulating resist film on the mask surface, scratching the resist film of the defective portion with a probe of the AFM, Moving the probe of the electrochemical AFM, removing the black defect by an electrochemical reaction in a state where the probe and the mask black defect portion are used as both electrodes and an electrolytic solution is interposed therebetween, and insulating the mask surface. Removing the film.   Grasping the position of the defective portion of the mask by a scanning microscope, applying an insulating resist film on the mask surface, removing the resist film of the defective portion by irradiating a charged particle beam, Moving the probe of the electrochemical AFM above the defect position, and removing the black defect by an electrochemical reaction in a state where the probe and the mask black defect portion are both electrodes and an electrolytic solution is interposed therebetween; Removing the insulating film from the mask surface.   4. The method according to claim 3, wherein the scanning microscope for obtaining the defect position information uses one of an AFM, a scanning ion microscope, and a scanning electron microscope.   A step of grasping the position of a defective portion of the mask by using a scanning microscope function of the FIB apparatus; a step of irradiating the central portion of the defect region excluding the peripheral portion with the FIB to perform etching while leaving the vicinity of the glass substrate; A method for repairing a mask black defect, comprising the steps of: removing a black defect remaining by an electrochemical reaction in a state where a portion is used as both electrodes and an electrolytic solution is interposed; and confirming the defect repair by an atomic force microscope.   6. The method according to claim 1, wherein a step of measuring a tunnel current flowing between the probe and the black defect and setting a proper short distance before the electrochemical reaction is performed. .   A probe of an atomic force microscope having a tip portion as an electrode, a processing cell containing an electrolyte and a mask as a sample, and applying a predetermined current or a predetermined voltage between the tip portion of the probe and the mask surface. It has a power supply and a mechanism for moving the position of the tip of the probe in the X, Y, and Z directions, and has an observation function as an atomic force microscope and a processing function for removing a mask black defect by an electrochemical reaction. A mask black defect repair apparatus characterized by the above-mentioned.   AFM probe having only the tip portion as an electrode, a processing cell for storing an electrolyte and a mask as a sample, a power supply for applying a predetermined current or voltage between the tip portion and the mask surface, A mechanism for moving the position of the tip of the probe in the X, Y, and Z directions, a function of observing the shape of the sample surface by two-dimensional scanning of the probe, and a defect obtained by the observation. A function of moving the probe to the position based on the position information and mechanically removing the resist film on the surface of the defect, and a processing function of removing a mask black defect by an electrochemical reaction using the tip electrode of the probe. A black defect correcting apparatus for a mask, comprising:   The function of mechanically removing the resist film on the defect surface is to store the position information of the defect region obtained by the observation function, to determine the resist film removal region based on the stored information, and to scan the removal region. 9. The apparatus according to claim 8, further comprising a computer for issuing a drive signal to a mechanism for moving the position of the needle tip in the X, Y, and Z directions.   A FIB device comprising a FIB column and a sample stage provided with at least a three-dimensional drive mechanism in a vacuum chamber, an AFM probe having only the tip portion as an electrode, and a processing cell for storing an electrolyte and a mask as a sample. A power source for applying a predetermined current or voltage between the tip of the probe and the mask surface, and a mechanism for moving the position of the tip of the probe in the X, Y, and Z directions. A black defect correcting apparatus having an observation function and a processing function of removing a mask black defect by an electrochemical reaction.   An electron beam apparatus including a sample stage having an electron beam column and at least a three-dimensional drive mechanism in a vacuum chamber, an AFM probe having an electrode at the tip, and a processing cell for storing an electrolyte and a mask as a sample. A power supply for applying a predetermined current or voltage between the tip of the probe and the mask surface, and a mechanism for moving the position of the tip of the probe in the X, Y, and Z directions. A black defect correcting apparatus having an observation function and a processing function of removing a mask black defect by an electrochemical reaction.   A FIB device having a SIM function for grasping a defect position and an etching function by beam irradiation, a probe of an atomic force microscope having a tip portion as an electrode, a processing cell for storing an electrolyte and a mask as a sample, A power supply for applying a predetermined current or a predetermined voltage between the tip of the probe and the mask surface, and a mechanism for moving the position of the tip of the probe in the X, Y, and Z directions are provided by the FIB apparatus. A mask black defect repair apparatus comprising a combination with an electrochemical AFM apparatus having a processing function of removing a mask black defect by an electrochemical reaction based on defect position information.   The power supply connected between the probe tip and the mask surface is capable of supplying a bias voltage and a pulse of a predetermined current or a predetermined voltage, and in addition to a processing function of removing a mask black defect by an electrochemical reaction, 13. The mask black defect correcting apparatus according to claim 7, further comprising an STM function for measuring and setting an appropriate shortest distance between the probe and the mask black defect.   A step of roughly processing a plate-shaped cantilever portion and a protruding probe portion from the tip thereof from the SOI silicon wafer by dry etching, and oxidizing silicon from the protruding probe portion from the surface by thermal oxidation to form a tip thereof. Producing a probe for electrochemical AFM, comprising: a step of sharpening a portion, a step of coating a metal thin film on the surface of the probe and the cantilever, and a step of coating the probe tip and a contact hole with an insulating layer except for a contact hole. Method.   15. The probe for electrochemical AFM according to claim 14, wherein the step of roughly processing the plate-shaped cantilever portion and the probe portion projecting from the tip thereof from the SOI silicon wafer is performed by mask patterning and reactive ion etching. Production method.   The step of coating the insulating layer except for the probe tip and the contact hole is to cover the entire surface with an insulating film and then remove the probe tip and the contact hole by a plasma etching technique. 3. The method for producing a probe for electrochemical AFM according to item 1.   16. The step of coating with an insulating layer except for the tip of the probe and the contact hole, after covering the whole with an insulating film, removing the tip of the probe and the contact hole by FIB etching. 3. The method for producing a probe for electrochemical AFM according to item 1.   A step of sharpening the hollow glass capillary in a heated state, a step of heating and cooling the sharpened tip a plurality of times to bend in one direction, a step of inserting a metal wire into the capillary, and both ends of the capillary. A method for producing a probe for an electrochemical AFM, comprising a step of sealing a portion with a resin and a step of sharpening a tip portion by electrolytic polishing.   19. A step of dip-coating a probe having undergone the step of claim 18 in molten Apiezon wax, a step of polishing a back surface of the probe to form a mirror surface, and sputter-coating a metal thin film around the mirror surface. A method for producing a probe for electrochemical AFM, comprising the steps of: immersing in chloroform and dissolving apiezone wax to remove a metal thin film other than a mirror surface.   A probe for an electrochemical AFM, wherein the probe is formed of a conductive material, the surface of which is covered with an insulating material, and only a tip portion is exposed.   The basic structure of the plate-shaped cantilever and the tip protruding from the tip is formed of silicon, and the silicon surface of the tip of the cantilever where the tip is formed and the tip of which is sharpened are coated with a metal coating. The electrochemical AFM probe has a structure in which an insulating layer is formed on an upper layer of the metal film except for a sharpened probe tip and a contact hole.   A metal wire is inserted into a glass capillary whose tip is sharpened and bent into a hook shape, and the metal wire is exposed and sealed with resin at the tip and rear ends, and the metal wire is exposed at the tip. Is a probe for electrochemical AFM characterized in that the tip diameter is sharpened to several hundred nanometers or less.   23. The probe for an electrochemical AFM according to claim 22, wherein a flat surface is machined on the back surface, and the surface of the surface is coated with a metal thin film to form a mirror surface.

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