JP4786899B2 - Mask blank glass substrate manufacturing method, mask blank manufacturing method, reflective mask blank manufacturing method, exposure mask manufacturing method, reflective mask manufacturing method, and semiconductor device manufacturing method - Google Patents

Description

The present invention relates to a glass blank manufacturing method, a mask blank manufacturing method, a reflective mask blank manufacturing method, an exposure mask manufacturing method, a reflective mask manufacturing method, and a semiconductor device manufacturing method, In particular, ArF excimer laser (exposure wavelength: 193 nm), F2 excimer laser (exposure wavelength: 157 nm), EUV (Extreme), which are exposure light sources used at 65 nm and 45 nm in semiconductor design rules.
Manufacturing method of mask blank glass substrate, mask blank manufacturing method, reflective mask blank manufacturing method, exposure mask manufacturing using ultra-violet light (exposure wavelength: 13 nm) as an exposure light source The present invention relates to a method, a reflective mask manufacturing method, and a semiconductor device manufacturing method.

In recent years, with the increase in density and accuracy of VLSI devices, the trend toward finer substrate surfaces required for mask blank glass substrates (referred to as glass substrates as appropriate) is becoming more severe year by year. In particular, as the wavelength of the exposure light source becomes shorter, the demand for the shape accuracy (flatness) of the substrate surface has become stricter, and a glass substrate for mask blanks with high flatness has been demanded.
For example, when the exposure light source is an F2 excimer laser, the required flatness of the glass substrate is 250 nm or less, and when the exposure light source is EUV light, it is 50 nm or less. That is, in a rectangular area of 142 mm long × 142 mm wide, a flatness of 50 nm or less is required with a PV value (difference between the maximum height and the minimum height with respect to the reference surface). The reason is that if the flatness of the glass substrate is poor, the dimensional accuracy of the pattern after exposure and transfer is deteriorated.

Conventionally, various precision polishing methods have been proposed for reducing the surface roughness of a mask blank glass substrate manufacturing method.
For example, Patent Document 1 discloses a technique of a precision polishing method in which a substrate surface is polished using a polishing agent mainly composed of cerium oxide and then finish-polished using colloidal silica. When polishing a glass substrate by such a polishing method, a batch-type double-side polishing machine is generally used in which a plurality of glass substrates are set and both surfaces thereof are polished simultaneously.

  According to the precision polishing method, it is theoretically possible to achieve the required smoothness by reducing the average grain size of the abrasive grains. However, since it is affected by mechanical accuracy such as the carrier that holds the glass substrate, the surface plate that sandwiches the glass substrate, and the planetary gear mechanism that moves the carrier, the flatness of the glass substrate that can be stably obtained is limited to about 500 nm. there were.

In recent years, in order to overcome the above limitations, a method for planarizing a glass substrate that performs local processing using plasma etching, a gas cluster ion beam, or a magnetic fluid has been proposed.
For example, in Patent Documents 2, 3, and 4, the surface of a glass substrate surface is measured by measuring the uneven shape of the glass substrate surface and surface-treating the region including the convex portion under the processing conditions corresponding to the convexity of the convex portion. A technique of a flattening method for flattening is disclosed.
In addition, when the flatness of the glass substrate surface is adjusted by plasma etching, gas cluster ion beam, or local processing using magnetic fluid, the surface roughness of the glass substrate surface generally occurs after these local processing. In order to improve surface roughness, it is necessary to polish (finish polishing) the surface of the glass substrate.

As a technique related to the above-described finish polishing, for example, in Patent Document 5, a flat plate is improved by applying a pressing load to the entire guide ring during polishing, in addition to the substrate to be polished, and further, the flat substrate is made stable. There has been proposed a technique of a polishing method for a square substrate that can be easily obtained.
According to this technology, it is possible to suppress the occurrence of scratches by using the same material as the substrate for the guide ring. Also, the guide ring is divided, and an arbitrary portion of the guide ring can be formed according to the substrate shape. By pressing against the polishing cloth, a square substrate with high flatness can be obtained regardless of the shape of the substrate to be polished before polishing.
JP-A 64-040267 JP 2002-316835 A Japanese Patent Application Laid-Open No. 08-293383 US2002 / 0081943A Publication JP 2003-048148 A

However, the technique of the above-described method for polishing a square substrate can achieve a flatness of about 230 nm as described in Patent Document 5, but the flatness of 50 nm, which is a target of the present inventors. There was a problem that it could not be applied to the following glass substrates for mask blanks.
That is, the glass substrate for mask blanks having a flatness of 50 nm or less after local processing needs to be polished (finish polishing) for the purpose of improving the surface roughness. For example, the processing pressure at the time of polishing can be reduced or the polishing time can be reduced. Although the surface roughness of the glass substrate is improved even if the time is set to an extremely short time, there is a problem that the flatness adjusted by folding and local processing is deteriorated.
Further, due to the above problem, there has been a problem that it is not possible to realize further higher density and higher accuracy of the ultimate LSI device.

The present invention has been made in view of the above problems, and in polishing a glass substrate surface subjected to local surface processing for the purpose of improving surface roughness by local surface processing, in the polishing step, the glass substrate While maintaining or improving the flatness of the surface, the surface roughness of the glass substrate surface can be improved, and a method for manufacturing a glass substrate for mask blanks having high flatness and high smoothness, a method for manufacturing mask blanks, and a reflective type It is an object of the present invention to provide a mask blank manufacturing method, an exposure mask manufacturing method, a reflective mask manufacturing method, and a semiconductor device manufacturing method.

In order to achieve the above object, the method for manufacturing a mask blank substrate according to the present invention includes a concavo-convex shape measuring step for measuring a concavo-convex shape on a measured surface of a mask blank glass substrate, and a measurement obtained in the concavo-convex shape measuring step. Based on the result, by performing surface processing on the region including the concavo-convex shape, the flatness control step of controlling the flatness of the surface to be measured to a predetermined reference value or less, and the surface processed When the surface of the glass substrate is pressed against the polishing cloth by the substrate pressing means and the glass substrate is rotated and polished, the polishing amount at each predetermined point on the surface of the glass substrate is constant. A polishing step of setting a pressing force, pressing the glass substrate against a polishing cloth with the pressing force, and polishing the glass substrate.
In this way, the surface roughness of the glass substrate surface can be improved while maintaining or improving the flatness of the glass substrate surface, and high flatness and high smoothness can be realized.

Moreover, the manufacturing method of the substrate for mask blanks of the present invention is a method in which, in the polishing step, the pressing force distribution on the glass substrate has an annular high pressing force band at the center of the glass substrate.
In this way, it is possible to polish the glass substrate having a flatness of several tens of nm while maintaining or improving the flatness.

Moreover, the manufacturing method of the mask blank substrate of the present invention is a method in which, in the polishing step, the substrate pressing means presses each of the regions independently for each of the plurality of regions of the divided glass substrate. .
In this way, the polishing operation can be performed efficiently by the substrate pressing means. In general, the substrate pressing means has a structure in which a pressing force control means is disposed in each region and each pressing force is controlled.

Moreover, the manufacturing method of the mask blank substrate of the present invention is a method in which the polishing cloth pressing means presses the polishing cloth in the vicinity of the outer peripheral portion of the glass substrate in the polishing step.
In this way, since the adverse effect of the restoring force of the polishing pad in the vicinity of the outer peripheral portion of the glass substrate can be reduced, high flatness of the glass substrate can be reliably realized.

Moreover, the manufacturing method of the board | substrate for mask blanks of this invention is based on the uneven | corrugated shape measurement process which measures the uneven | corrugated shape in the to-be-measured surface of the glass substrate for mask blanks, and the measurement result obtained by the said uneven | corrugated shape measurement process. A flatness control step of controlling the flatness of the surface to be measured to a predetermined reference value or less by applying surface processing to the region including the concavo-convex shape, and the glass substrate surface subjected to the surface processing. When the glass substrate is rotated and polished while being pressed against the polishing cloth by the substrate pressing means, the glass substrate is pressed against the polishing cloth so that the pressure distribution on the surface of the glass substrate becomes uniform, and polishing is performed. The cloth pressing means includes a polishing step of polishing the glass substrate while pressing the polishing cloth in the vicinity of the outer peripheral portion of the glass substrate.
Even in this case, the surface roughness of the glass substrate surface can be improved while maintaining or improving the flatness of the glass substrate surface, and high flatness and high smoothness can be realized.

In the mask blank substrate manufacturing method of the present invention, the polishing cloth pressing means presses each outer peripheral region independently for each of a plurality of outer peripheral regions in the vicinity of the outer peripheral portion of the divided glass substrate. As a way to do.
In this way, for example, the adverse effect of the restoring force of the polishing cloth in the vicinity of the center and corners of the side of the rectangular glass substrate can be reduced more accurately, so that the high flatness of the glass substrate can be further ensured. Can be realized.

In order to achieve the above object, the mask blank manufacturing method of the present invention is a mask blank glass substrate manufactured by any one of the mask blank glass substrate manufacturing methods described above. As a method of forming.
In this way, it is possible to manufacture high-quality mask blanks that are excellent in flatness and smoothness and can improve the dimensional accuracy of the pattern after exposure transfer.

Moreover, in order to achieve the said objective, the manufacturing method of the mask for exposure in this invention is a method of patterning the thin film of the mask blank manufactured with the manufacturing method of the said mask blanks, and forming a thin film pattern on the said glass substrate.
In this way, it is possible to manufacture a high-quality exposure mask that is excellent in flatness and smoothness and can improve the dimensional accuracy of the pattern after exposure transfer.

In order to achieve the above object, a method for manufacturing a semiconductor device according to the present invention includes an exposure mask manufactured by the above-described exposure mask manufacturing method, and the exposure mask is formed by lithography using the exposure mask. This is a method for transferring a thin film pattern onto a semiconductor substrate.
In this way, it is possible to manufacture a semiconductor device such as a VLSI device that can realize higher density and higher accuracy than the current level.

  As described above, according to the present invention, when a glass substrate surface subjected to local surface processing is polished for the purpose of improving surface roughness by local surface processing, the flatness of the glass substrate surface is maintained in the polishing step. Alternatively, the surface roughness of the glass substrate surface can be improved while improving, and a glass substrate for mask blanks, a mask blank, an exposure mask, and a semiconductor device having high flatness and high smoothness can be manufactured. In addition, the dimensional accuracy of the pattern after exposure transfer can be greatly improved, and further higher density and higher accuracy of the ultimate VLSI device can be realized.

[Manufacturing method of glass substrate for mask blanks]
FIG. 1: has shown the schematic flowchart figure for demonstrating the manufacturing method of the glass substrate for mask blanks concerning embodiment of this invention.
In the figure, the method for producing a glass substrate for mask blanks of the present invention includes a preparation step (P1) for preparing a glass substrate, an uneven shape measuring step (P2) for measuring the uneven shape on the surface of the glass substrate, and local processing. It has a flatness control step (P3) for controlling the flatness of the glass substrate surface and a polishing step (P4) for finish polishing the glass substrate surface.

<Preparation process>
The preparation step is a step of preparing a glass substrate in which one surface or both surfaces are precisely polished and the surface roughness of the glass substrate is set to a desired surface roughness. The surface roughness is preferably set to 0.4 nm or less in terms of root mean square roughness RMS from the viewpoint of measurement accuracy in the subsequent uneven shape measurement step and processing efficiency in the flatness control step.
In general, the preparation step (P1) includes a rough polishing step for rough polishing both surfaces of a glass substrate, and a precision polishing step for precisely polishing one or both surfaces of the rough-polished glass substrate. Is done. At this time, in the rough polishing process, an abrasive in which cerium oxide having relatively large abrasive grains is dispersed is used, and in the precision polishing process, an abrasive in which colloidal silica having relatively small abrasive grains is dispersed is used. The

The glass substrate is not particularly limited as long as it is used as mask blanks. For example, synthetic quartz glass, soda lime glass, aluminosilicate glass, borosilicate glass, alkali-free glass and the like can be mentioned.
However, in the case of a glass substrate for mask blanks for F2 excimer laser exposure, synthetic quartz glass doped with fluorine is used in order to suppress the absorption of the exposure light source as much as possible.
In the case of a glass substrate for EUV mask blanks, in order to suppress distortion of the transferred pattern due to heat during exposure, it is within the range of about 0 ± 1.0 × 10 ⁻⁷ / ° C., more preferably about 0 ± 0. A glass material having a low coefficient of thermal expansion in the range of 3 × 10 ⁻⁷ / ° C. is used.
Furthermore, since many films are formed on a glass substrate for EUV mask blanks, a glass material with high rigidity that can suppress deformation due to film stress is used. In particular, a glass material having a high Young's modulus of 65 GPa or more is preferable. For example, amorphous glass such as SiO ₂ —TiO ₂ glass or synthetic quartz glass, or crystallized glass on which β-quartz solid solution is deposited is used.

  Here, preferably, after the above-described precision polishing and before measuring the uneven shape of the surface to be measured on the glass substrate, opposite to the surface to be measured (the front surface of the substrate) A surface treatment may be performed on the back surface of the substrate on the side with a solvent containing an acid or an alkali that is corrosive to the glass substrate. In this way, since fine scratches and the like existing on the measured surface and the back surface of the glass substrate can be removed, the uneven shape can be measured with higher accuracy. In addition, the surface treatment can also provide an effect of cleaning the substrate surface, eliminate measurement errors due to contamination, and perform accurate measurement.

<Uneven shape measurement process>
The concavo-convex shape measuring step is a step of measuring the concavo-convex shape (flatness) of the surface to be measured of the glass substrate prepared in the preparation step.
An optical interferometer is usually used for measuring the uneven shape on the surface to be measured of the glass substrate. A typical optical interferometer irradiates and reflects coherent light on the surface to be measured of the glass substrate and interferes with the measuring machine reference surface (front reference surface) to measure the difference in height of the surface to be measured as interference fringes. The phase difference is calculated from (light intensity) and measured.

On the other hand, the features of the present invention will be described with reference to the drawings.
FIG. 2: has shown the schematic for demonstrating the measurement state in the uneven | corrugated shape measurement process of the manufacturing method of the glass substrate for mask blanks concerning embodiment of this invention.
In the figure, a surface shape measurement processing device 2 includes a surface shape measurement device including a wavelength modulation laser light source 21, a CCD camera 22, a front reference surface A, and a rear reference surface D (referred to as surfaces A and D as appropriate). It comprises means 20, a measurement data processing device 26 provided with data analysis means 23, machining amount calculation means 24 and machining condition determination means 25.

  In the surface shape measurement processing apparatus 2, a glass substrate 1 for mask blanks having a measured surface B and a back surface C (abbreviated as surfaces B and C as appropriate) between the surface A and the surface D is set. Is done. At this time, in order to identify each interference fringe, the distance between the surfaces A and B is L1, the plate thickness of the glass substrate 1 (the distance between the surfaces B and C) is T, and the distance between the surfaces C and D is When L2 is set and the distance between the surfaces A and D is L3, the glass substrate 1 is set so that each distance is different, that is, L1 ≠ T ≠ L2 ≠ L3.

  The surface shape measuring means 20 uses the wavelength modulation laser light source 2 as a light source, irradiates the glass substrate 1 for mask blanks with the wavelength modulation laser, and changes the wavelength of the wavelength modulation laser minutely. When the wavelength-modulated laser is irradiated, interference fringes on the surface (A + B) (interference fringes generated by interference between the reflected light from the surface A and the reflected light from the surface B), and the interference fringes on the surface (A + C) Group, surface (A + D) interference fringe group, surface (B + C) interference fringe group, surface (B + D) interference fringe group, surface (C + D) interference fringe group, and these interference fringe groups are CCD cameras. 22 is read.

  The data analysis means 23 receives the image data of each interference fringe group from the CCD camera 22, detects the difference in frequency of each interference fringe group by Fourier transform technology, and separates each interference fringe group. That is, it has a function of separating the interference fringe group on the surface (A + B) and the interference fringe group on the surface (C + D) from the plurality of interference fringe groups.

The data analysis means 23 can calculate the height difference of the surface to be measured B from the phase difference of the interference fringe group on the surface (A + B), and measure the uneven shape of the surface to be measured B. In this embodiment, since the rear reference plane D is provided, the data analysis unit 23 separates the interference fringe group on the surface (C + D), and determines the back surface from the phase difference of the interference fringe group on the surface (C + D). The difference in height of C can be calculated and the uneven shape of the back surface C can be measured. These measurement results do not include, for example, measurement errors due to reflected light from the back surface C of the glass substrate 1 or measurement errors due to striae inside the glass substrate 1, so that the flatness control process in the next process is processed. The conditions can be accurately determined. As a result, the flatness can be controlled with extremely high accuracy, and a glass substrate for mask blanks having high flatness can be manufactured.
In addition, the measured surface flatness can be calculated from the uneven shape measurement data of the measured surface B, and the back surface flatness can be calculated from the uneven shape measurement data of the back surface C.

  The data analysis means 23 can separate the interference fringe group of the surface (A + D) with the glass substrate 1 removed, and can calculate L3 from the phase difference of the interference fringe group of the surface (A + D). L1 and L2 can be calculated from the interference fringe group on the surface (A + B) and the interference fringe group on the surface (C + D), respectively. Here, since the distances L1, L2, and L3 are measured with extremely high accuracy, the thickness T (= L3-L1-L2) of the glass substrate 1 at an arbitrary measurement position can be easily and accurately calculated. Further, a variation in plate thickness (appropriately referred to as plate thickness variation (TTV) as appropriate) can be calculated from the plate thickness T at each measurement position. In addition, the uneven | corrugated shape and board thickness dispersion | variation of the to-be-measured surface B and the back surface C of the glass substrate 1 can be calculated | required substantially simultaneously.

  The measurement results of the uneven shape and the plate thickness variation of the glass substrate 1 are stored in a recording medium (not shown) such as a computer, and then the processing amount calculation means 24 uses the measurement results and a predetermined reference set in advance. It is compared with a value (required flatness, variation in plate thickness), and the difference is calculated for each predetermined region (for example, a region of 5 mm length × 5 mm width) of the measurement target surface B of the glass substrate 1. That is, the machining allowance is set according to the heights of the convex portions of the measured surface B and the back surface C of the glass substrate 1. This difference (machining allowance) is a necessary machining amount for each predetermined region in local surface machining.

The processing condition determination means 25 determines the processing conditions so that the required processing amount can be efficiently removed by the local processing machine 27. That is, by dividing the required processing amount by the processing amount per unit time by the spot of the local processing machine 27, the spot residence time is calculated, and subsequently the spot residence time at each position is calculated for the entire surface to be processed, Determine work feeding schedule efficiently.
Thus, according to the surface shape measurement processing apparatus 2, the measurement of the glass substrate 1 is performed based on the measurement results regarding the uneven shape of the measurement surface B and the back surface C of the glass substrate 1 and the variation in the thickness of the glass substrate 1. The surface B and the back surface C can be efficiently processed, and a glass substrate for mask blanks having both high flatness and a high level of parallelism (for example, 50 nm PV or less) can be manufactured. .
In addition, you may perform said arithmetic processing in any of an uneven | corrugated shape measurement process or a flatness control process.

<Flatness control process>
In the flatness control step, the flatness of the surface to be measured in the glass substrate is less than or equal to a predetermined reference value by performing surface processing on the region including the concavo-convex shape based on the measurement result obtained in the concavo-convex shape measuring step. It is a process to control.
The surface processing is performed according to processing conditions set for each predetermined region on the surface to be measured of the glass substrate. As described above, this processing condition is the difference between the uneven shape of the measured surface of the glass substrate measured by the optical interferometer and the preset flatness reference value (necessary processing amount for local surface processing). Set based on.

  The parameters of the processing conditions vary depending on the local processing machine 27, but are set so that the removal amount increases as the convexity of the convex portion increases. For example, when the processing method of local surface processing is ion beam or plasma etching, the higher the convexity of the convex portion, the slower the moving speed of the ion beam or plasma generating housing, or Control to increase the intensity of the beam or plasma.

  In addition, there is MRF (Magneto Rheological Finishing) as a processing method for local surface processing. MRF is a method in which polishing abrasive grains contained in a magnetic fluid are brought into contact with a workpiece (glass substrate) with the aid of a magnetic field, and the residence time of the contact portion is controlled to perform polishing locally. is there. In this polishing process, the longer the convexity of the convex part, the longer the residence time of the contact part by the abrasive grains. Further, the smaller the convexity of the convex part, the shorter the residence time of the contact part by the abrasive grains is controlled.

3A and 3B are schematic diagrams for explaining a processing state by the MRF processing method in the flatness control step of the present embodiment, where FIG. 3A is a front sectional view and FIG. 3B is a side sectional view.
In this figure, according to the MRF processing method, polishing abrasive grains (not shown) contained in a magnetic fluid 41 containing iron (not shown) are used for mask blanks which are workpieces with the aid of a magnetic field. The glass substrate 1 is brought into contact with the glass substrate 1 at high speed and the residence time of the contact portion is controlled to perform local polishing. That is, a mixed liquid (magnetic polishing slurry 4) of the magnetic fluid 41 and the polishing slurry 42 is put into the disc-shaped electromagnet 3 that is rotatably supported, and the tip thereof is used as a local processing polishing spot 5 to be removed. The convex portion 13 is in contact with the polishing spot 5. In this manner, the magnetic polishing slurry 4 is distributed along the magnetic field on the disk, the polishing slurry 42 is distributed on the glass substrate 1 side, and the magnetic fluid 41 is distributed on the magnet 3 side. Flowing. A part of this state is used as a polishing spot 5 for locally polishing, and is brought into contact with the surface of the glass substrate 1, whereby the convex portion 13 is locally polished and controlled to a flatness of several tens of nm.

In this MRF processing method, unlike the conventional polishing method, since the polishing spot 5 is always flowing, there is no deterioration in processing accuracy due to wear of the processing tool or shape change, and the glass substrate 1 is pressed with a high load. Since there is no need, there is an advantage that there are few latent scratches and scratches in the surface displacement layer.
In the MRF processing method, when the glass substrate 1 is moved while the polishing spot 5 is in contact, the moving speed of the glass substrate 1 is controlled according to the processing allowance (required processing amount) set for each predetermined region. Therefore, the removal amount can be easily adjusted.

  As the polishing slurry 42 mixed with the magnetic fluid 41, a slurry in which fine abrasive particles are dispersed in a liquid is used. The abrasive particles are, for example, silicon carbide, aluminum oxide, diamond, cerium oxide, zirconium oxide, manganese oxide, colloidal silica, and the like, and are appropriately selected according to the material of the workpiece, the processed surface roughness, and the like. These abrasive particles are dispersed in a liquid such as water, an acidic solution, or an alkaline solution to form an abrasive slurry 42 and mixed with the magnetic fluid 41.

The local processing method by plasma etching is a local processing method in which a plasma generating housing is positioned above a surface portion to be removed and an etching gas is allowed to flow to etch the removed portion. That is, when an etching gas is flowed, neutral radical species generated in the plasma collide isotropically with the surface to be measured of the glass substrate, and this portion is etched. On the other hand, since no plasma is generated in the portion where the plasma generating casing is not located, the etching gas is not etched even if it contacts.
When the plasma generating casing is moved on the glass substrate, the removal amount is adjusted by controlling the moving speed and plasma intensity of the plasma generating casing in accordance with the required processing amount of the surface to be measured of the glass substrate.

  The plasma generation housing has a structure in which a glass substrate is sandwiched between electrode pairs. A plasma is generated between the substrate and the electrode by a high frequency, and radical species are generated by passing an etching gas therethrough, or an etching gas is guided. There is a system in which plasma is generated by oscillation of microwaves through a tube, and a flow of generated radical species collides with a surface to be measured of a glass substrate.

  The etching gas is appropriately selected according to the material of the glass substrate. For example, a halogen compound gas or a mixed gas containing a halogen compound is used. Specifically, tetrafluoromethane, trifluoride methane, hexafluoride ethane, octafluoride propane, decafluorobutane, hydrogen fluoride, sulfur hexafluoride, nitrogen trifluoride, carbon tetrachloride, tetrafluoro Examples include silicon fluoride, trichlorochloromethane, and boron trichloride.

The local processing method by ion beam (gas cluster ion beam irradiation) is a gaseous substance at normal temperature and normal pressure, for example, oxide, nitride, carbide, rare gas substance, or a mixed gas thereof (the above substances are appropriately used). The gas cluster of these substances is formed using a gas cluster ion beam that is ionized by electron irradiation to the solid, while controlling the irradiation area as necessary. This is a local processing method for irradiating the surface (glass substrate surface).
A cluster is usually composed of a group of several hundred atoms or molecules, and even if the acceleration voltage is 10 kV, each atom or molecule is irradiated as an ultra-slow ion beam of several tens eV or less, so that it is extremely low. The glass substrate surface can be treated with damage.

When this measurement surface of a glass substrate is irradiated with this gas cluster ion beam, the molecules or atoms that make up the cluster ions and the atoms on the surface to be measured collide in multiple stages, and reflected molecules or atoms that have lateral motion components. Give rise to Thereby, selective sputtering occurs at the convex portion of the surface to be measured of the glass substrate, and the surface to be measured can be flattened. This flattening phenomenon can also be obtained from the effect of preferentially sputtering atoms present on a surface or grain having a weak binding force by energy concentratedly applied to the surface to be measured of the glass substrate.
In addition, about the production | generation of gas cluster itself, as already well-known, it can produce | generate by ejecting the gas of a pressurization state in a vacuum device through an expansion type nozzle. The gas cluster generated in this way can be ionized by irradiation with electrons.
Examples of the gaseous substance include oxides such as CO ₂ , CO, N ₂ O, NOx, and CxHyOz, and rare gases such as O ₂ , N ₂ , Ar, and He.

The flatness required for the glass substrate for the mask blank is determined according to the wavelength of the exposure light source used in the mask blank, and the flatness control standard in the flatness control process is determined according to the required flatness. The value is determined.
For example, in the case of a mask blank glass substrate for F2 excimer laser exposure, the flatness control reference value is 250 nm or less, and in the case of an EUV mask blank glass substrate, the flatness control reference value is 50 nm or less for local processing. Is called.

<Polishing process>
The polishing step is a step of polishing the glass substrate surface for the purpose of improving the surface roughness generated on the glass substrate surface in the above-described unevenness control step. Therefore, it is preferable to carry out by a polishing method in which the surface roughness is improved while maintaining or improving the flatness created by local surface processing.

4A and 4B are schematic views for explaining a polishing state in the polishing step of the present embodiment, wherein FIG. 4A is a longitudinal sectional view, and FIG. 4B is an EE sectional view.
In the figure, a polishing apparatus 6 is provided with a polishing cloth 61, a polishing surface plate 62 rotatably supported, a plurality of pressing bodies 63 and a plurality of pressing control means 64 arranged in a matrix, and an elastic body. 65 and an abrasive cloth pressing body 66, and includes a substrate pressing means 67 that is rotatably supported. Further, the polishing cloth pressing body 66 is composed of pressing bodies having various shapes according to the outer shape of the glass substrate 1 and is disposed around the glass substrate 1. Although not shown, each pressing force is controlled. The

The feature of the present invention is that when the polishing step after the unevenness control step is performed by rotating the glass substrate 1 while pressing the surface of the glass substrate 1 subjected to surface processing against the polishing cloth 61 by the substrate pressing means 67. The pressing force is set for each point so that the polishing amount at each predetermined point on the surface of the glass substrate 1 is constant, and the glass substrate 1 is pushed against the polishing cloth 61 for each point with the set pressing force. This is to polish the glass substrate 1.
For example, in the present embodiment, the pressing force of the pressing body 63 a arranged in a rectangular ring shape is increased so that the pressing force distribution on the glass substrate 1 has an annular high pressing force band at the center of the glass substrate 1. As a way to do. In this way, it is possible to polish the glass substrate 1 having a flatness of several tens of nm while maintaining or improving the flatness.
Further, in the polishing step, the pressing body 63 presses each region independently for each of the plurality of regions of the divided glass substrate 1, so that the polishing operation can be performed efficiently.

The substrate pressing means 67 can reduce the adverse effect of the restoring force of the polishing cloth 61 near the outer periphery of the glass substrate 1 because the polishing cloth pressing body 66 presses the polishing cloth 61 near the outer periphery of the glass substrate 1. And high flatness of the glass substrate 1 can be realized with certainty.
Here, it is preferable that the polishing pad pressing body 66 preferably presses each outer peripheral region independently for each of a plurality of outer peripheral regions in the vicinity of the outer peripheral portion of the divided glass substrate 1. In this way, for example, the adverse effect of the restoring force of the polishing pad 61 in the vicinity of the center and corners of the side of the rectangular glass substrate 1 can be reduced more accurately. Can be more reliably realized.

  More preferably, the pressing body 63 and / or the polishing cloth pressing body 66 are controlled so that the pressing force of the glass substrate 1 against the polishing cloth 61 can be controlled in each region divided according to the unevenness shape whose flatness is controlled. It is preferable to pressurize each of the plurality of divided areas independently. In this way, the flatness obtained in the flatness control step can be further improved.

As the polishing apparatus 6 used in the polishing process, for example, a processing apparatus having a function of controlling the pressing force in a divided region from the back surface of the glass substrate 1 is used.
In setting the pressing force distribution, the pressing force distribution is set according to the uneven shape of the glass substrate 1, and specifically, a large pressing force is set for the convex portion and a small pressing force is set for the concave portion. Also, a special pressure distribution that does not break the flat shape may be set.
Furthermore, in the present embodiment, the glass substrate 1 is flattened as much as possible in the flatness control step, and the polishing process is performed so as not to break the flat shape, but the idea is changed and the polishing characteristics of the polishing apparatus 6 are changed. Accordingly, a method of controlling the flat shape of the glass substrate 1 in the flatness control step and realizing excellent flatness at the stage of polishing by the polishing apparatus 6 may be adopted.

As described above, according to the method for manufacturing a glass substrate for mask blanks according to the present embodiment, the polishing step is performed to polish the glass substrate surface subjected to local surface processing for the purpose of improving surface roughness by local surface processing. The surface roughness of the glass substrate surface can be improved while maintaining or improving the flatness of the glass substrate surface, and high flatness and high smoothness can be realized.
The present invention is not limited to the above-described embodiment. For example, in the polishing step, the substrate pressing unit 67 may remove the glass substrate 1 from the polishing cloth 61 so that the pressing force distribution on the glass substrate 1 is uniform. The glass substrate 1 may be polished while the polishing cloth pressing means 66 presses the polishing cloth 61 near the outer periphery of the glass substrate 1. Even if it does in this way, the surface roughness of the glass substrate 1 can be improved, maintaining or improving the flatness of the glass substrate 1. FIG.

[Manufacturing method of mask blanks]
Next, an embodiment of a method for manufacturing a mask blank according to the present invention will be described.
This mask blank manufacturing method includes the steps of manufacturing the glass substrate 1 by the above-described mask blank glass substrate manufacturing method, and a thin film that becomes a mask pattern (transfer pattern) on the main surface of the manufactured glass substrate 1. Forming the step.
By the way, mask blanks are classified into transmissive mask blanks and reflective mask blanks. The mask blank of this embodiment can be applied to any mask blank, and a thin film to be a transferred pattern is accurately formed on the glass substrate 1. A resist film may be formed on the thin film.

Mask blanks are classified into transmissive mask blanks and reflective mask blanks. In any mask blanks, a thin film to be a transferred pattern is formed on the glass substrate 1. A resist film may be formed on the thin film.
In addition, the thin film formed on the transmissive mask blank is a thin film that causes an optical change with respect to the exposure light (light emitted from the exposure light source) used when transferring to the transfer target. For example, the exposure light And a phase shift film that changes the phase difference of exposure light.

As a light shielding film, in general, a Cr film, a Cr alloy film that selectively contains oxygen, nitrogen, carbon, and fluorine in Cr, a laminated film thereof, a MoSi film, and a MoSi alloy that selectively contains oxygen, nitrogen, and carbon in MoSi Examples thereof include films and laminated films thereof.
As the phase shift film, in addition to the SiO ₂ film having only the phase shift function, a metal silicide oxide film, a metal silicide nitride film, a metal silicide oxynitride film, and a metal silicide oxycarbide having a phase shift function and a light shielding function Examples thereof include a film, a metal silicide oxynitride carbide film (metal: transition metal such as Mo, Ti, W, and Ta), a halftone film such as a CrO film, a CrF film, and a SiON film.

In the reflective mask blank, a laminated film including a reflective multilayer film (multilayer reflective film) and a light absorber film (absorber layer) to be a transferred pattern is formed on the glass substrate 1.
As the light reflecting multilayer film, Ru / Si periodic multilayer film, Mo / Be periodic multilayer film, Mo compound / Si compound periodic multilayer film, Si / Nb periodic multilayer film, Si / Mo / Ru periodic multilayer film, Si / Mo / Materials such as a Ru / Mo periodic multilayer film and a Si / Ru / Mo / Ru periodic multilayer film are used.

As the light absorber film, Ta or Ta alloy (for example, a material containing Ta and B, a material containing Ta, B and N), Cr or Cr alloy (for example, at least one of nitrogen, oxygen, carbon and fluorine in Cr) Material with two elements added).
The transmission type mask blank uses g-line (wavelength: 436 nm), i-line (wavelength: 365 nm), KrF (wavelength: 246 nm), ArF (wavelength: 193 nm), F2 (wavelength: 157 nm) as an exposure light source. In the reflective mask blank, EUV (for example, wavelength: 13 nm) is used as an exposure light source.
In addition, the above-mentioned thin film can be formed by sputtering methods, such as DC sputtering, RF sputtering, and ion beam sputtering, for example.

  Thus, according to the mask blank manufacturing method of the present embodiment, the flatness and smoothness are excellent, and the dimensional accuracy of the pattern after exposure transfer can be improved.

[Exposure Mask Manufacturing Method]
Next, an embodiment of a transfer mask manufacturing method according to the present invention will be described.
The transfer mask manufacturing method includes a step of manufacturing a mask blank with a resist film by the above-described mask blank manufacturing method, and a resist pattern forming step of forming a desired resist pattern on the resist film through drawing / development processing, etc. And a thin film pattern forming step of forming a thin film pattern on a glass substrate for mask blanks by masking the resist pattern and etching away the thin film.

  In a photomask which is a transmission type transfer mask, a desired resist pattern is formed on the resist film of the photomask blank in which a light-shielding film and a resist film are formed on a mask blank glass substrate through drawing / development processing, etc. Thereafter, the light shielding film is removed by etching using this resist pattern as a mask, and finally the resist film is removed to obtain a photomask in which the light shielding film pattern is formed on the glass substrate for mask blanks.

  In addition, in the halftone phase shift mask that is a transmissive transfer mask, the resist film of the halftone phase shift mask blank in which a halftone film, a light-shielding film, and a resist film are formed on a mask blank glass substrate is used. After forming a desired resist pattern through drawing / development processing, etc., this resist pattern is used as a mask to remove the light-shielding film, and a light-shielding film pattern is formed. Using this light-shielding film pattern as a mask, halftone film is etched By removing the resist film and the light-shielding film at the end, a halftone phase shift mask in which a halftone film pattern is formed on the glass substrate for mask blanks is obtained.

  In a reflective mask, which is a reflective transfer mask, drawing / development is performed on the resist film of the reflective mask blank in which a light reflective multilayer film, a light absorber film, and a resist film are formed on a mask blank glass substrate. After forming a desired resist pattern through processing, etc., the light absorber film is etched away using this resist pattern as a mask, and finally the resist film is removed, whereby the light absorber film pattern is formed on the light reflecting multilayer film. A reflection type mask in which is formed is obtained.

  Thus, according to the method for manufacturing an exposure mask according to the present embodiment, the flatness and smoothness are excellent, and the dimensional accuracy of the pattern after exposure transfer can be improved.

[Method for Manufacturing Semiconductor Device]
Next, an embodiment of a semiconductor device manufacturing method according to the present invention will be described.
In this semiconductor manufacturing apparatus manufacturing method, an exposure mask is manufactured by the above-described exposure mask manufacturing method, and a thin film pattern of the exposure mask is transferred onto a semiconductor substrate by lithography using the exposure mask. As a way to do. At this time, the semiconductor substrate has a conductive film to be a circuit pattern and a resist film, and the transfer mask is reduced and exposed to about 1/4 or 1/5 times so that a desired circuit pattern is formed into a resist film. The semiconductor device in which a desired circuit pattern is formed on the semiconductor substrate can be obtained by patterning the conductive film using the resist film as a mask.
In this way, it is possible to manufacture a semiconductor device such as a VLSI device that can realize higher density and higher accuracy than the current level.

[Examples and Comparative Examples]
Hereinafter, embodiments of the present invention will be described with reference to a glass substrate for EUV mask blanks (hereinafter referred to as a glass substrate), an EUV reflective mask blank, and an EUV reflective mask manufacturing method as examples. It is not limited to.

(Example 1)
Using a double-side polishing apparatus, a SiO ₂ —TiO ₂ -based glass substrate (size is approximately 152.) which is polished stepwise with cerium oxide abrasive grains or colloidal silica abrasive grains and surface-treated with a low concentration of silicic acid. 4 mm × about 152.4 mm and a thickness of about 6.35 mm). The surface roughness of the obtained glass substrate was about 0.15 nm in terms of root mean square roughness (RMS) (measured with an atomic force microscope).

Irregular shapes (surface morphology, flatness) and TTV (plate thickness variation) on the front and back surfaces (measured surface and back surface) of this glass substrate were measured with a wavelength shift interferometer using a wavelength-modulated laser (measurement area of about 148 mm). X about 148 mm).
As described above, this wavelength shift interferometer has a difference in height of the measurement surface from the interference fringes between the reflected light reflected from the measurement surface and the back surface of the glass substrate and the measuring machine reference surface (front reference surface). Is calculated as a phase difference, the frequency difference of each interference fringe is detected, and the interference fringe with the measuring machine reference surface (front reference surface) by the reflected light reflected from the measured surface and the back surface of the glass substrate is separated. The uneven shape of the surface to be measured is measured. In this example, a measuring machine reference surface (rear reference surface) was further provided on the back surface side of the glass substrate, and the uneven shape on the back surface of the glass substrate and the thickness variation of the glass substrate were also measured.

As a result, the flatness of the measured surface and the back surface of the glass substrate was about 290 nm (convex shape). The flatness refers to the PV value (difference between the maximum value and the minimum value) calculated by defining the reference plane by the method of least squares with the measured surface as a reference.
The measurement results of the concavo-convex shape (surface morphology, flatness) of the measurement surface of the glass substrate by the wavelength shift interferometer are stored in a computer as height information with respect to the reference plane for each measurement point, and glass for EUV mask blanks. Compared to the reference value 50 nm (convex shape) of the measured surface flatness required for the substrate, the reference value 50 nm (convex shape) of the back surface flatness, and the reference value 50 nm of TTV (plate thickness variation), the difference (required processing amount) ) Was calculated on a computer.

Next, the processing conditions of the local surface processing according to the required processing amount were set for each processing spot shape region in the glass substrate surface.
Using a dummy substrate in advance, the dummy substrate is processed with spots without moving the substrate for a certain time in the same way as in actual processing, and the shape is the same as the apparatus for measuring the uneven shape of the measured surface and the back surface. It measured with the measuring machine and calculated the processing volume of the spot per time unit. Then, the scanning speed for raster scanning the glass substrate was determined according to the required processing amount obtained from the spot information and the uneven shape information of the glass substrate. For example, the processing amount is large in a portion where the scanning speed is slow, and the processing amount is small in a portion where the scanning speed is fast.

  According to the set processing conditions, the measured surface flatness, back surface flatness, and TTV (plate thickness variation) of the glass substrate by the MRF (magneto-rheological fluid) processing method using the substrate finishing device with magnetic fluid manufactured by QED. ) Was subjected to local surface processing so that the surface shape was adjusted to be equal to or less than the above reference value.

  When the uneven shape (surface form, flatness) of the measured surface and the back surface of the glass substrate after performing shape adjustment by local surface processing by MRF is measured, the flatness of the measured surface and the back surface is about 40 to 50 nm. TTV (plate thickness variation) was also 50 nm or less, which was good. Moreover, when the surface roughness of the to-be-measured surface and the back surface of the glass substrate was measured, the root-mean-square roughness RMS was about 0.37 nm, which was a state rougher than the surface roughness before local surface processing by MRF. became.

  Next, for the front and back surfaces of the glass substrate 1, the glass substrate 1 is set in a single-sided single wafer polishing machine capable of controlling the intentionally set pressing force distribution (8 × 8 matrix) shown in FIG. went.

The polishing conditions were as follows.
Processing liquid: alkaline aqueous solution (NaOH) + abrasive (concentration: 2 wt%),
pH: 11
Abrasive: colloidal silica, average particle size: about 70 nm
Polishing platen rotation speed: 1-50rpm
Polishing plate rotation speed: 1-50rpm
Retainer ring load: 500-5000gf
In-plane pressure: 0 to 0.5 kgf / mm ²
Region E (see FIG. 5): 0.3 to 0.5 kgf / mm ²
Region F: 0.15 to 0.30 kgf / mm ²
Region G: 0.05 to 0.15 kgf / mm ²
Area H: 0 to 0.05 kgf / mm ²
Polishing time: 1 to 10 minutes Thereafter, the glass substrate was washed with an alkaline aqueous solution (NaOH) to obtain a glass substrate for EUV mask blanks.

In addition, the above-mentioned processing surface pressure is locally applied so that the processing amount is constant at each point with respect to the uneven shape (convex part) of the surface of the glass substrate, taking into account the processing performance of the movement by rotation. This is a polishing condition for maintaining or flattening the concavo-convex shape (surface shape) adjusted by the MRF under the condition of applying pressure to the polishing.
Thereafter, the glass substrate was washed with an alkaline aqueous solution (NaOH) to obtain a glass substrate for EUV mask blanks.

  When the flatness, TTV (plate thickness variation), and surface roughness of the obtained glass substrate were measured with the above-described measuring apparatus, the surface flatness was about 30 nm, the backside flatness was about 30 nm, and the TTV (plate thickness). The variation was about 50 nm or less, which was better than the surface shape before the polishing step and was favorable. Moreover, the surface roughness of the front and back surfaces was about 0.13 nm in terms of root mean square roughness RMS, and the rough state of the glass substrate surface before the polishing step could be improved.

(Example 2)
Next, the polishing conditions in the polishing step after the local surface processing in Example 1 described above are performed only by adjusting the load of the polishing pad pressing body 66, and the pressing force distribution in the substrate surface is made uniform. Similarly, a glass substrate for EUV mask blanks was produced. In addition, the conditions of the local surface processing were adjusted so as to be the same as those in Example 1 with respect to the flatness and TTV (plate thickness variation) of the front and back surfaces of the glass substrate before the polishing process (after the local surface processing). .
The flatness of the front and back surfaces of the glass substrate after MRF processing was about 50 nm, and the TTV (plate thickness variation) was about 50 nm or less.

The polishing conditions were as follows.
Processing liquid: alkaline aqueous solution (NaOH) + abrasive (concentration: 2 wt%),
pH: 11
Abrasive: colloidal silica, average particle size: about 70 nm
Polishing platen rotation speed: 1-50rpm
Polishing plate rotation speed: 1-50rpm
Retainer ring load: 500-5000gf
In-plane pressure: 0.01 kgf / mm ²
Polishing time: 1 to 10 minutes Thereafter, the glass substrate was washed with an alkaline aqueous solution (NaOH) to obtain a glass substrate for EUV mask blanks.

  When the flatness, TTV (plate thickness variation), and surface roughness of the obtained glass substrate were measured by the above-described measuring apparatus, the front and back flatness was about 50 nm, and the TTV (plate thickness variation) was about 50 nm or less. Thus, the state of the surface shape before the polishing step was maintained, which was good. Further, the surface roughness of the front and back surfaces was about 0.13 nm in terms of root mean square roughness RMS, and the rough state of the glass substrate surface before the polishing step could be improved.

(Comparative example)
A glass substrate for EUV mask blanks was produced in the same manner as in Example 1 except that the polishing step was performed by single-sided single-wafer polishing with a retainer ring. The polishing conditions for single-sided single wafer polishing were as follows.
Processing liquid: alkaline aqueous solution (NaOH) + abrasive (concentration: 2 wt%),
pH: 11
Abrasive: colloidal silica, average particle size: about 70 nm
Polishing platen rotation speed: 1-50rpm
Polishing plate rotation speed: 1-50rpm
Processing pressure: 0.1-10 kPa
Polishing time: 1 to 10 minutes Thereafter, the glass substrate was washed with an alkaline aqueous solution (NaOH) to obtain a glass substrate for EUV mask blanks.

When the flatness, TTV (plate thickness variation), and surface roughness of the obtained glass substrate were measured by the above-described measuring apparatus, the surface roughness was a good root mean square roughness RMS of about 0.15 nm. However, the flatness of the front and back surfaces was about 250 nm to 500 nm, which was worse than the state before single-sided single-wafer polishing and before the shape adjustment by local surface processing. The TTV (plate thickness variation) was about 2 to 3 μm.
As a result, it was not possible to obtain a glass substrate that satisfies the specifications required for a glass substrate for EUV mask blanks.

  Next, as shown in FIG. 6, an Si film (film thickness: about 4.2 nm) and an Mo film are formed on the glass substrate 201 obtained by the above-described Examples 1 and 2 and the comparative example by DC magnetron sputtering. After stacking about 40 cycles (film thickness: about 28 nm) as a cycle, a Si film (film thickness: about 11 nm) was formed to form a multilayer reflective film 202. Next, by the same DC magnetron sputtering method, a chromium nitride (CrN) film (film thickness: about 30 nm) is used as the buffer layer 203 on the multilayer reflective film 202, and a TaBN film (film thickness: about 60 nm) is used as the absorber layer 204. It formed and the EUV reflective mask blanks 200 were obtained.

  The obtained EUV reflective mask blanks were measured for flatness, surface roughness, and thickness variation (TTV). In Example 1, the thickness was about 30 nm, about 0.13 to 0.17 nm, and about 50 nm, respectively. In Example 2, it was about 50 nm, about 0.13-0.17 nm, and about 50 nm, and in the comparative example, it was about 100-150 nm, about 0.13 nm, and about 200 nm.

Next, by using this EUV reflective mask blank 200, an EUV reflective mask 200a having a pattern for a 16 Gbit DRAM having a design rule of 0.0 μm was manufactured.
First, a resist for electron beam irradiation (not shown) was applied and formed on the EUV reflective mask blanks 200, developed by drawing with an electron beam, and a resist pattern (not shown) was formed.
Using this resist pattern as a mask, the absorber layer 204 was dry-etched with chlorine to form an absorber layer pattern 204a on the buffer layer 203.

Further, the resist pattern remaining on the absorber layer pattern 204a was removed with hot sulfuric acid.
Thereafter, the buffer layer 203 was dry-etched with a mixed gas of chlorine and oxygen according to the absorber layer pattern 204 a to form the buffer layer pattern 203 a on the multilayer reflective film 202. Thus, the buffer layer pattern 203a / absorber layer 204a was formed on the multilayer reflective film 202 to obtain an EUV reflective mask 200a.

Next, a method for transferring a pattern by EUV light to a semiconductor substrate with a resist using the EUV reflective mask 200a will be described.
FIG. 7 is a schematic diagram for explaining a pattern transfer method using a reflective mask according to an example and a comparative example of the present invention.
In the figure, a pattern transfer apparatus 100 includes a laser plasma X-ray source 101, an EUV reflective mask 101, a reduction optical system 102, and the like. The reduction optical system 102 is configured by using the X-ray reflection mirror 103, and the pattern reflected by the EUV reflection mask 200a is reduced to about ¼. Since the wavelength band of 13 to 14 nm is used as the exposure wavelength, it was set in advance so that the optical path was in vacuum.

In this state, EUV light obtained from the laser plasma X-ray source 101 is incident on the EUV reflective mask 200a, and the light reflected here is incident on the resist-coated semiconductor substrate via the reduction optical system 102. Transcribed.
In other words, the light incident on the EUV reflective mask 200a is absorbed and not reflected by the absorber layer in a portion having the absorber layer pattern, while the light incident on the portion without the pattern of the absorber layer is multi-layered. Reflected by the reflective film. In this way, the pattern formed by the reflected light from the EUV reflective mask 200 a is transferred to the resist layer on the semiconductor substrate 110 via the reduction optical system 102.

  Using the EUV reflective mask 200a made of the glass substrate obtained in Examples 1 and 2 and the comparative example, pattern transfer was performed on the semiconductor substrate 110 by the pattern transfer method described above. As a result, EUV reflection according to Examples 1 and 2 was performed. It was confirmed that the accuracy of the mold mask 200a was 16 nm or less, which is the required accuracy of the 0.07 μm design rule. On the other hand, the accuracy of the EUV reflective mask 200a according to the comparative example could not satisfy the required accuracy of the 0.07 μm design rule of 16 nm or less.

As mentioned above, about the manufacturing method of the glass substrate for mask blanks of this invention, the manufacturing method of mask blanks, the manufacturing method of reflective mask blanks, the manufacturing method of the mask for exposure, the manufacturing method of a reflective mask, and the manufacturing method of a semiconductor device Although the preferred embodiment has been described and described, a method for manufacturing a glass substrate for mask blanks according to the present invention, a method for manufacturing a mask blank, a method for manufacturing a reflective mask blank, a method for manufacturing an exposure mask, and a method for manufacturing a reflective mask The method and the semiconductor device manufacturing method are not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the present invention.
For example, instead of the substrate pressing means 67 described above, a structure in which the glass substrate 1 is pressed against the polishing cloth 61 with a pressing mold (not shown) formed with unevenness so as to generate a pressing force according to each region. It may be a thing.
The polishing cloth pressing body may also have a structure in which the pressure is not controlled for each of a plurality of outer peripheral regions in the vicinity of the outer peripheral portion of the divided glass substrate.

As described above, a method for manufacturing a glass substrate for mask blanks, a method for manufacturing a mask blank, a method for manufacturing a reflective mask blank, a method for manufacturing an exposure mask, a method for manufacturing a reflective mask, and a semiconductor device In the manufacturing method, the manufacturing object is a glass substrate for mask blanks, a mask blank, a reflective mask blank, an exposure mask, a reflective mask, and a semiconductor device, but is not limited to this, for example, extremely excellent It can utilize suitably also for the board | plate material which requires flatness and smoothness.

The schematic flowchart figure for demonstrating the manufacturing method of the glass substrate for mask blanks concerning embodiment of this invention is shown. The schematic for demonstrating the measurement state in the uneven | corrugated shape measurement process of the manufacturing method of the glass substrate for mask blanks concerning embodiment of this invention is shown. It is the schematic explaining the processing state by the MRF processing method in the flatness control process of this embodiment, (a) is front direction sectional drawing, (b) has shown side surface sectional drawing. It is the schematic explaining the grinding | polishing state in the grinding | polishing process of this embodiment, (a) is a longitudinal cross-sectional view, (b) has shown EE sectional drawing. The schematic for demonstrating the processing surface pressure distribution of the glass substrate in Example 1 of this invention is shown. It is the schematic explaining the manufacturing method of the reflective mask concerning the Example and comparative example of this invention, (a) is an expanded sectional view of a reflective mask blank, (b) is an expanded sectional view of a reflective mask. Show. The schematic diagram explaining the pattern transfer method by the reflective mask concerning the Example and comparative example of this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass substrate for mask blanks 2 Surface shape measurement processing apparatus 3 Electromagnet 4 Magnetic polishing slurry 5 Polishing spot 6 Polishing apparatus 13 Convex part 20 Surface shape measurement means 21 Wavelength modulation laser light source 22 CCD camera 23 Data analysis means 24 Processing amount calculation means 25 processing condition determining means 26 measurement data processing device 41 magnetic fluid 42 polishing slurry 61 polishing cloth 62 polishing surface plate 63, 63a pressing body 64 pressing control means 65 elastic body 66 polishing cloth pressing body 67 substrate pressing means 100 pattern transfer apparatus 101 laser Plasma X-ray source 102 Reduction optical system 103 X-ray reflection mirror 110 Semiconductor substrate 200 EUV reflection type mask blanks 200a EUV reflection type mask 201 Glass substrate 202 Multilayer reflection film 203 Buffer layer 203a Buffer layer pattern 204 Absorber layer 204a Absorber layer Turn A front reference surface B measured surface C backside D rear reference plane E region F region G region H region

Claims (13)

A concavo-convex shape measuring step for measuring the concavo-convex shape on the surface to be measured of the glass substrate for mask blanks,
Flatness control for controlling the flatness of the surface to be measured to be equal to or lower than a predetermined reference value by performing surface processing on the region including the uneven shape based on the measurement result obtained in the uneven shape measuring step. Process,
When polishing the glass substrate by rotating the glass substrate while pressing the glass substrate surface subjected to surface processing against the polishing cloth by the substrate pressing means, the polishing amount at each predetermined point on the glass substrate surface is constant. And setting a pressing force for each point, a polishing step of polishing the glass substrate by pressing the glass substrate against a polishing cloth with the pressing force,
I have a,
The method of manufacturing a glass substrate for mask blanks , wherein the polishing step has a distribution of pressing force on the glass substrate having an annular high pressing force band at a central portion of the glass substrate. 2. The manufacturing of a glass substrate for mask blanks according to claim 1, wherein in the polishing step, the substrate pressing unit presses each of the regions independently for each of a plurality of divided regions of the glass substrate. Method. The method for producing a glass substrate for mask blanks according to claim 1 or 2 , wherein in the polishing step, a polishing cloth pressing means presses the polishing cloth in the vicinity of the outer peripheral portion of the glass substrate. The said uneven | corrugated shape measurement process measures each uneven | corrugated shape of a to-be-measured surface and the back surface of the said glass substrate, and plate | board thickness dispersion | variation, The glass substrate for mask blanks in any one of Claims 1-3 characterized by the above-mentioned. Production method. The uneven shape measuring step includes
Irradiation of a wavelength-modulated laser onto the surface to be measured of the glass substrate, minutely changing the wavelength of the wavelength-modulated laser, and interference fringes between the reflected light reflected from the surface to be measured and the back surface of the glass substrate, respectively, and the front reference surface Detecting the difference in the frequency of fluctuation, eliminating interference by reflected light from the back surface of the glass substrate, and using the reflected light reflected from the measured surface of the glass substrate, the unevenness of the measured surface on the glass substrate Measure the shape
5. The unevenness shape of the back surface of the glass substrate is measured using a rear reference surface set on the back surface side of the glass substrate, and the plate thickness variation of the glass substrate is further measured. The manufacturing method of the glass substrate for mask blanks in any one. In the flatness control step, the back surface is flattened by applying surface processing to a region including the back surface uneven shape based on the measurement result of the back surface uneven shape obtained in the uneven shape measurement step. The method for manufacturing a glass substrate for mask blanks according to claim 4 or 5, wherein the degree is controlled to be equal to or less than a predetermined reference value. The flatness control step performs surface processing on the glass substrate by any one of an MRF processing method, a plasma etching method, or an ion beam method. The manufacturing method of the glass substrate for mask blanks of crab. A method for producing a mask blank, comprising: forming a thin film to be a mask pattern on a glass substrate for a mask blank produced by the method for producing a glass substrate for a mask blank according to any one of claims 1 to 7 . The light absorption which forms a multilayer reflective film on the glass substrate for mask blanks manufactured with the manufacturing method of the glass substrate for mask blanks in any one of Claims 1-7, and becomes a mask pattern on the said multilayer reflective film A method for producing a reflective mask blank, comprising forming a body film. A reflective mask blank manufactured by the reflective mask blank manufacturing method according to claim 9, wherein a light absorber film is patterned to form a light absorber film pattern on the glass substrate. Production method. A method for producing an exposure mask, comprising: patterning a thin film of a mask blank produced by the method for producing a mask blank according to claim 8 to form a thin film pattern on the glass substrate. An exposure mask is manufactured by the method for manufacturing an exposure mask according to claim 11, and the thin film pattern of the exposure mask is transferred onto a semiconductor substrate by lithography using the exposure mask. A method for manufacturing a semiconductor device. A reflective mask is manufactured by the reflective mask manufacturing method according to claim 10, and the light absorber film pattern of the reflective mask is transferred onto a semiconductor substrate by lithography using the reflective mask. A method of manufacturing a semiconductor device.

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