JP4634992B2 - Position measuring apparatus and positional deviation amount measuring method - Google Patents

Description

  The present invention relates to a position measuring apparatus and a positional deviation amount measuring method, for example, a method for measuring a pattern positional deviation amount of a mask used for extreme ultraviolet (EUV) exposure drawn while variably shaping an electron beam. And an apparatus.

  In recent years, the circuit line width of semiconductors has become increasingly narrower, while large integration has continued. In order to engrave a circuit on a silicon (Si) wafer in a large amount and accurately, an exposure technique for transferring an original image drawn on a mask (also referred to as an original image pattern or a reticle) has been advanced. For example, an optical proximity effect correction technique in which an auxiliary pattern that is not transferred around the original mask pattern is being studied. Alternatively, a modified illumination technique that partially improves the resolution by giving anisotropy to illumination light used for transfer has been studied. Alternatively, an immersion exposure technique that improves the resolution limit by putting a liquid (for example, water or oil) larger than the refractive index of air between the objective lens and the wafer has been studied. As a result, a pattern of 90 nm or less, which is half of the wavelength of the exposure light source 193 nm, can be produced. In particular, in the immersion exposure technique, it is shown that a 45 nm pattern can be exposed from the theoretical refractive index of water. Therefore, it is considered that if an ideal oil is found, it can be achieved by the immersion technique up to a position close to 32 nm.

  However, in such an exposure technique, it is assumed that an auxiliary pattern for correcting the optical proximity effect becomes complicated. The auxiliary pattern is a pattern that is not originally transferred to the wafer but has an effect when an image is formed on the wafer. This auxiliary pattern is formed on the mask. This auxiliary pattern becomes complicated as the influence of the aerial image increases. In addition, a complicated pattern has a great influence on the drawing time when drawing an original picture. In addition, there is a very big problem of how to inspect the drawn pattern.

  In order to solve the above problem, it is considered to shorten the exposure wavelength itself as in the history of lithography so far. The light of 157 nm has been abandoned due to the limitation of the lens material for reduced transfer. Therefore, it is EUV light having a wavelength of 13.4 nm that is considered to be most likely at the present time. Since EUV light is transmitted and absorbed by many objects with light divided into a soft X-ray region, it is no longer possible to form a projection optical system. Therefore, a reflection optical system has been proposed for an exposure method using EUV light.

Therefore, it is proposed that the original mask used is not a method of holding the periphery at three points or four points to transmit transmitted light as in the prior art, but chucks most of the back surface with a flat surface. . Further, in consideration of light attenuation, the system itself is installed in a vacuum chamber. Therefore, it is assumed that an electrostatic chuck is used for fixing an EUV mask.
The specifications of the substrate to be exposed and the electrostatic chuck itself are strictly defined as defined in the SEMI standard (see, for example, Non-Patent Documents 1 to 3).

  Furthermore, the deformation of the substrate during the process of forming the reflective film or the pattern formation process when making an EUV original mask is unpredictable. Therefore, according to Non-Patent Document 3 described above, the holding of the substrate by the electrostatic chuck is indispensable for the drawing device, the position measuring device, and the exposure device (also referred to as a transfer device) for making the original image mask.

FIG. 24 is a conceptual diagram for explaining the operation of a conventional variable shaping type electron beam drawing apparatus.
In a first aperture 410 in a variable shaping type electron beam drawing apparatus (EB (Electron beam) drawing apparatus), a rectangular, for example, rectangular opening 411 for forming the electron beam 330 is formed. Further, the second aperture 420 is formed with a variable shaping opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture 410 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 of the first aperture 410 is deflected by a deflector. Then, the sample 340 mounted on a stage that passes through a part of the variable shaping opening 421 of the second aperture 420 and continuously moves in a predetermined direction (for example, the X direction) is irradiated. . That is, a rectangular shape that can pass through both the opening 411 and the variable shaping opening 421 is drawn in the drawing region of the sample 340 mounted on the stage. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is referred to as a variable shaping method.

  However, it is very difficult to satisfy the shape accuracy specification of the chuck described in the SEMI standard (SEMI P40-1103) and to evaluate the satisfaction. Further, the particle diameter of particles allowed in the EUV mask manufacturing process is 30 nm according to the roadmap of SEMATECH. However, the back surface of the EUV mask is coated with a conductive film such as Cr having good adhesion to glass for electrostatic chucking. In the case of a method such as an electrostatic chuck having a large contact area with the mask, there is a sufficient possibility that the conductive film on the back surface will be peeled off due to friction at the contact portion and become particles.

  Also, if there are particles on the back side of the EUV mask, the EUV mask may be deformed because the back side of the mask does not adhere close to the particles when viewed locally, and the required pattern position accuracy may not be obtained. . Therefore, it is necessary to keep the chuck surface clean at all times, but it is very difficult to maintain and manage it.

  Further, in the exposure apparatus, since the mask is generally used as an original image for sequentially reducing and transferring the image onto the wafer, only the mask that has passed through the final cleaning process is handled. However, in a drawing apparatus at the stage of manufacturing an EUV mask, it is necessary to put an EUV mask coated with a resist, which is a photosensitive agent, into the apparatus as in the case of drawing a pattern on an optical mask. Examples of the optical mask described here include an optical mask used when exposure is performed using light such as ultraviolet rays other than EUV light. The resist applied on the EUV mask, like a normal optical mask, acts as a photosensitive material and causes a chemical reaction to a desired pattern drawn with an electron beam. As a result, only the portion of the pattern that has been altered by irradiation with the electron beam is removed in a later development process (positive type resist) or by removing other than the portion of the irradiated pattern (negative type resist). A resist pattern is drawn. After that, the resist pattern was used as a protective film, and the lower layer of chromium was removed by etching, and the chromium-based metal or tantalum-based metal that would be a light-shielding film was removed by etching. It becomes a mask that allows light to pass through only the points. Thereafter, the resist left as an etching protective film is removed by chemical stripping.

  This resist needs to be applied thinly and uniformly, whether it is an optical mask or an EUV mask. Generally, a resist is made of a polymer film containing carbon as a main component, and a predetermined amount is dropped onto a rotating substrate on which a resist dissolved in a solvent is rotated. It is applied by a spin coating technique for spin coating. At this time, there is a possibility that the resist partially wraps around the side and back of the substrate, but residues and deposits such as resist on the side and back will affect the resist at the necessary locations on the mask surface. It is very difficult to get rid of. Note that after the resist is applied, the resist is baked (pre-baked) at a predetermined temperature in accordance with the type and conditions of the resist mainly for stabilizing and uniforming the sensitivity.

  However, even if the baking process is performed, the resist that is a polymer film has the property of being easily damaged and easily peeled off. In the drawing device, in order to transport the substrate and hold it during drawing, it is handled by avoiding the necessary part of the mask surface and touching only the minimum necessary part. It is easily considered that the resist that wraps around the side surface and the back surface adheres to or peels off from the contact portion and is a major cause of dust generation in the drawing apparatus. In addition, when an electrostatic chuck is used in an EUV mask, most of the back surface of the mask comes into contact with it, so that deposits such as resist remaining on the side surface and the back surface are peeled off and become particles, resulting in electrostatic chucking. It is fully expected to be sucked. Therefore, it becomes difficult to maintain the chuck surface in a clean state. As a result, particles enter between the electrostatic chuck surface and the mask back surface, making it difficult to maintain the mask back surface on an ideal plane.

  Therefore, the backside shape of the substrate is measured during or before drawing while holding the substrate serving as a mask with a drawing apparatus without using an electrostatic chuck, and the pattern position is shifted based on the measured backside shape of the substrate. A pattern drawing method has been proposed in which the amount is calculated and corrected (see, for example, Patent Document 1).

  However, the technique described in Patent Document 1 measures the height position distribution of the back surface facing the surface on which the substrate pattern is formed. When such a method is employed, there is a possibility that the amount of deflection is changed for each substrate in accordance with the tolerance of the substrate, in addition to being affected by the deflection of its own weight when measuring the back surface of the substrate. Alternatively, the amount of deformation may change with the change in the multilayer film characteristic of the EUV mask for each substrate. Therefore, there may be a problem in reproducibility when reproducing a state in which the back surface of the substrate is corrected to an arbitrary aspect or plane by calculation. Further, as a height distribution measuring device, there is a measuring device using an interferometer which is generally used for measuring the flatness of an EUV mask. However, it is very difficult to mount this measuring instrument on a drawing apparatus due to restrictions on the apparatus configuration. Therefore, there is a possibility that the resolution of the mountable measuring instrument is not sufficient.

Then, even if the drawing apparatus can draw, a problem occurs in the position measuring apparatus that measures the position of the drawn pattern. That is, since the mask measured by the position measuring apparatus is also a substrate before final cleaning, there is a possibility that residues such as resist or particles adhered in the process are left. If such an EUV mask is held by the electrostatic chuck, the particles are attracted to the electrostatic chuck. Therefore, it becomes difficult to maintain the chuck surface in a clean state. Furthermore, since the current position measurement device requires highly accurate measurement, it must be installed in a constant temperature chamber in which temperature and humidity are controlled in order to reduce environmental fluctuation. However, since there is no need to operate in a vacuum when measuring the position of the pattern, it is desirable to use it in the atmosphere where handling and management of the apparatus are easy. However, when the electrostatic chuck is used in the atmosphere, there is a great risk that foreign substances present in the environment are actively sucked by static electricity. As a result, particles enter between the electrostatic chuck surface and the mask back surface. Therefore, it becomes difficult to maintain the mask back surface on an ideal plane. As a result, there is a possibility that highly accurate position measurement cannot be performed.
JP 2004-214415 A SEMI P38-1103 SPECIFICATION FOR ABSORBING FILM STACKS AND MULTILAYERS ON EXTREME ULTRAVIOLET LITHOGRAPHY MASK BLANKS SEMI P37-1102 SPECIFICATION FOR EXTREME ULTRAVIOLET LITHOGRAPHY MASK SUBSTRATES SEMI P40-1103 SPECIFICATION FOR MOUNTING REQUIREMENTS AND ALIGNMENT REFERENCE LOCATIONS FOR EXTREME ULTRAVIOLET LITHOGRAPHY MASKS

  As described above, there is a problem that it is very difficult to manufacture the electrostatic chuck itself that satisfies the specifications even when the electrostatic chuck is used to hold the EUV mask in the position measuring apparatus. Even if it becomes possible to use an electrostatic chuck that satisfies the specifications, there are problems such as particle management in the position measurement device. Even if it is possible to use an electrostatic chuck that satisfies the specifications, there are the following problems. That is, with respect to a pattern drawn by data correction without using an electrostatic chuck, the position accuracy of the drawing apparatus could not be evaluated by the electrostatic chuck.

  It is an object of the present invention to provide a method and apparatus for overcoming such problems and measuring the pattern displacement amount of a drawn mask with high accuracy.

The position measurement device according to one embodiment of the present invention includes:
An arrangement portion for arranging a three-point support member for supporting the back surface of the mask substrate at three points, and a vacuum chuck member for vacuum chucking the back surface of the mask substrate;
A stage for placing one of the three-point support member and the vacuum chuck member arranged in the arrangement unit;
A vacuum pump that sucks the substrate through the vacuum chuck member in a state where the vacuum chuck member is placed on the stage;
A recognition unit for recognizing the position of the pattern formed on the substrate supported by the three-point support member placed on the stage and the position of the pattern formed on the substrate vacuum chucked by the vacuum chuck member;
It is provided with.

  By disposing the three-point support member and the vacuum chuck member in the disposition portion, it is possible to select a substrate holding member to be used on the stage. When the vacuum chuck member is selected, the substrate can be vacuum chucked by evacuating and sucking the back surface of the substrate through the vacuum chuck member by a vacuum pump. And the position of the pattern formed on the board | substrate hold | maintained at the selected one of a three-point support member and a vacuum chuck member can be recognized by the recognition part.

Further, in the present invention, the substrate is electrostatically chucked to the electrostatic chuck member in the transfer device when used for exposure with extreme ultraviolet light in the transfer device as a mask used for extreme ultraviolet exposure,
The placement portion is characterized in that a vacuum chuck member is formed in which the area and shape of the suction surface of the vacuum chuck member are matched to the area and shape of the suction surface of the electrostatic chuck member.

  With this configuration, it is possible to make the conditions equivalent to the case of holding with a vacuum chuck and the case of holding with an electrostatic chuck. Therefore, when measuring the position of the pattern corrected so as to be drawn at the same position as when it is corrected to a flat surface as in the case where the back surface of the substrate is held by an electrostatic chuck specified by the SEMI standard, a vacuum is used. If the substrate is placed on the chuck member, it can be confirmed whether or not a pattern is drawn at a desired position on the substrate while being held by the vacuum chuck on the stage as in the case of electrostatic chucking. On the other hand, when measuring the position of a pattern that is not corrected assuming that it is held by an electrostatic chuck specified by the SEMI standard, if the substrate is placed on a three-point support member, it is supported on the stage at three points. It is possible to confirm whether or not a pattern is drawn at a desired position on the substrate while being held by.

  Furthermore, a material harder than the material used for the electrostatic chuck member is used as the material for the vacuum chuck member.

  By using a material harder than the material used for the electrostatic chuck member, the amount of deformation of the vacuum chuck member when chucked can be reduced. As a result, the deformation error can be reduced and it can be brought close to an ideal plane. Therefore, reproducibility at the time of measurement can be improved.

  The position measuring device according to the present invention preferably further includes a control device that controls the suction force of the vacuum pump described above.

  In addition, it is preferable that the position measuring device further includes a gas supply unit that supplies gas via a vacuum chuck member.

  The position measuring device is preferably controlled so that the pressure of the suction surface of the vacuum chuck member is higher than the external pressure using the gas described above when the substrate is peeled from the vacuum chuck member.

  Further, it is preferable that the position measuring device is controlled so as to release gas through the vacuum chuck member when the substrate is not vacuum chucked on the vacuum chuck member.

  The vacuum chuck member preferably has a sensor for detecting the position of the substrate.

  As a sensor, it is preferable to use a capacitance type sensor or an optical sensor.

  The vacuum chuck member preferably includes a first suction mechanism that sucks the central portion of the back surface and a second suction mechanism that sucks the peripheral portion of the central portion when the back surface of the substrate is vacuum chucked.

  When the back surface of the substrate is vacuum chucked, it is preferable to use different suction forces for the first suction mechanism and the second suction mechanism.

  Further, when vacuum-chucking the back surface of the substrate, it is preferable that the peripheral portion is sucked by the second suction mechanism after the central portion of the back surface is sucked by the first suction mechanism.

  Further, the vacuum chuck member preferably has a sensor for detecting that the central portion of the back surface is attracted to the suction surface of the vacuum chuck member.

In addition, a plurality of vacuum chuck members are arranged in the arrangement part,
Each of the plurality of vacuum chuck members preferably has an identification mark.

Further, the positional deviation amount measuring method of one embodiment of the present invention includes:
When measuring the positional deviation amount in order to evaluate the positional accuracy assumed when the pattern transferred to the EUV mask is transferred onto the wafer, the back surface of the mask is planarized by selectively using a vacuum chuck. To correct and measure,
Wherein by selectively using three-point support method in measuring the positional deviation amount of the pattern drawn on the no correction of the mask backside shape for purposes of state management of the drawing device for drawing the EUV mask Measured without correcting the shape of the back surface of the mask to a flat surface .

  Here again, the vacuum chuck member may be formed in accordance with the area and shape of the suction surface of the electrostatic chuck member in which the area and shape of the suction surface of the vacuum chuck member are standardized.

  The vacuum chuck member may be formed of a material harder than the low thermal expansion material used for the electrostatic chuck member.

In addition, the misregistration amount measuring method according to another aspect of the present invention includes:
Based on the three-dimensional shape of the back surface of the substrate when the influence of its own weight is excluded, the pattern displacement amount predicted when the pattern is drawn on the surface of the substrate when the back surface of the substrate is corrected to a flat surface is corrected and drawn. A first misregistration amount measuring step of measuring the misregistration amount of the first pattern by vacuum-chucking the back surface of the substrate using the first pattern formed;
Supporting three points on the back side of the substrate using the second pattern drawn by correcting the amount of positional deviation of the pattern predicted when the pattern is drawn on the surface of the substrate without correcting the back side of the substrate to a flat surface. A second misregistration amount measuring step for measuring a misregistration amount of the second pattern;
It is provided with.

With such a configuration, it is possible to obtain the deformation amount of the surface of the substrate when it is corrected to a flat surface as in the case where the back surface of the substrate is held by an electrostatic chuck specified by the SEMI standard. An electrostatic chuck that defines the back surface of the substrate in accordance with the SEMI standard by measuring the positional deviation amount of the first pattern using the first pattern drawn by correcting the positional deviation amount of the pattern due to the deformation amount. Whether or not a pattern is drawn at the same position as when it is corrected to a flat surface as in the case of holding can be confirmed in a vacuum chucked state . In the other hand, the second deviation amount measurement step, when the substrate back surface as in the case of holding by supporting three points of the substrate back surface is not corrected in a plane without using an electrostatic chuck specified in the SEMI standard, It can be confirmed whether or not a pattern is drawn at a desired position. As a result, it is possible to confirm the validity of the positional deviation correction amount unique to the drawing apparatus.

  Here again, the vacuum chuck member may be formed in accordance with the area and shape of the suction surface of the electrostatic chuck member in which the area and shape of the suction surface of the vacuum chuck member are standardized.

  The vacuum chuck member is preferably formed of a material harder than the material used for the electrostatic chuck member.

According to the present invention, it is possible to confirm a pattern position deviation drawn by a drawing apparatus that does not use an electrostatic chuck by three-point support and to correct a pattern position of a pattern that is corrected assuming that it is held by an electrostatic chuck. Misalignment can also be confirmed. Further, Ru can see the pattern position shift without using the electrostatic chuck. In addition, according to another aspect of the present invention, it is possible to confirm the positional accuracy of both the corrected pattern and the uncorrected pattern assuming the case of holding by an electrostatic chuck.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may be used.

  Hereinafter, in the embodiment, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may be used.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram showing the configuration of the position measuring apparatus according to the first embodiment.
In FIG. 1, a position measurement apparatus 600 includes a housing 602, a pattern position recognition unit 610, a stage 620, a position control system 622, a surface plate 630, a transfer robot 640, a holder 650 as an example of an arrangement unit, a robot control circuit 646, A computer 660, a memory 662, a vacuum pump 680, and a stage control circuit 674 are provided. A pattern position recognition unit 610 such as a CCD camera, a stage 620, a position control system 622, a surface plate 630, a transfer robot 640, and a holder 650 are arranged in the housing 602. A robot control circuit 646, a memory 662, a vacuum pump 680, and a stage control circuit 674 are connected to the computer 660 and are controlled by the computer 660.

Further, the inside of the housing 602 is kept at a constant temperature, and the surface plate 630 has a vibration isolation function. The holder 650 has a plurality of arrangement locations (storage locations). Then, the three-point support member 220 and the first set of the sample 101 placed on the three-point support member 220, or the vacuum chuck member 240 and the vacuum chuck member 240 are placed in a plurality of stages. A second set of samples 101 is stored. The transfer robot 640 has a hand 642 and a main body 644. Then, the transfer robot 640 controlled by the robot control circuit 646 uses the hand 642 to carry out the first set or the second set from the holder 650 and transfer it onto the stage 620. Further, the transfer robot 640 uses the hand 642 to carry out the first set or the second set from the stage 620 and store it in the holder 650.
Here, FIG. 1 shows components necessary for explaining the first embodiment. In addition, the position measurement apparatus 600 may include other necessary configurations.

FIG. 2 is a conceptual diagram showing an example of the configuration of the three-point support member in the first embodiment.
As shown in FIG. 2, three support pins 222 are disposed on the three-point support member 220. Then, the back surface of the sample 101 is supported by the three support pins 222. The support pins 222 are preferably made of a hard material such as ruby or sapphire. By forming the sample 101 with a hard material, deformation of the support pin 222 when the sample 101 is placed can be suppressed. As a result, the error can be reduced. Therefore, the reproducibility is excellent.

FIG. 3 is a conceptual diagram showing an example of the configuration of the vacuum chuck member in the first embodiment.
As shown in FIG. 3, the vacuum chuck member 240 is formed with an adsorption surface so as to adsorb the entire back surface excluding the outer peripheral portion of the sample 101. The specification of the attracting surface is matched with the electrostatic chuck defined in the SEMI standard described above. That is, the area and shape of the suction surface of the vacuum chuck member 240 are formed in accordance with the area and shape of the suction surface of the electrostatic chuck member.

FIG. 4 is a conceptual diagram illustrating an example of a cross section of the electrostatic chuck according to the first embodiment.
FIG. 5 is a conceptual diagram showing an example of a cross section of the vacuum chuck in the first embodiment.
As shown in FIG. 4, the electrostatic chuck member 230 has suction portions 232 formed at a predetermined pitch defined by the SEMI standard. Then, the back surface of the substrate to be the sample 101 is adsorbed to the adsorbing portion 232 and corrected to a flat surface. When the sample 101 is a mask for EUV (Extreme Ultra Violet), it is used for transfer later by a transfer device. In that case, the electrostatic chuck is used by being electrostatically chucked by an electrostatic chuck member defined by the SEMI standard in the transfer apparatus. Therefore, when measuring the EUV mask using the position measuring device 600, it is desirable to reproduce the same state as when held by the electrostatic chuck. Therefore, in the first embodiment, also in the vacuum chuck, as shown in FIG. 5, in the vacuum chuck member 240, the contact surface 244 and the suction part 242 are the same as the suction part 232 at a predetermined pitch specified in the SEMI standard. Form in shape and area. The chuck is sucked by the vacuum pump through the flow path formed in the vacuum chuck member 240 where the opening portion becomes the suction portion 242. Although not shown here, the vacuum pump 680 sucks the substrate through the stage 620 and the vacuum chuck member 240 in a state where the vacuum chuck member 240 is placed on the stage 620. In this way, the sample 101 is adsorbed on the contact surface 244.

  As described above, the area and shape of the suction surface of the vacuum chuck member 240 are formed in accordance with the area and shape of the suction surface of the electrostatic chuck member specified in the SEMI standard, so that even when held by the vacuum chuck, The conditions can be the same as when held by an electric chuck. Therefore, when measuring the position of the pattern corrected so as to be drawn at the same position as when corrected to a flat surface, such as when the back surface of the substrate serving as the sample 101 is held by an electrostatic chuck specified by the SEMI standard For this, a substrate may be placed on the vacuum chuck member 230. Thereby, it can be confirmed whether or not a pattern is drawn at a desired position on the substrate while being held by the vacuum chuck on the stage 620 as in the case of electrostatic chucking. On the other hand, when measuring the position of a pattern that is not corrected assuming that it is held by an electrostatic chuck defined by the SEMI standard, a substrate may be placed on the three-point support member 220. Thereby, it is possible to confirm whether or not a pattern is drawn at a desired position on the substrate while being held by the three-point support on the stage 620.

  Here, the inventors have corrected the drawing position at the drawing position as described below, so that the pattern position is the same as when the electrostatic chuck is used in the drawing apparatus without using the electrostatic chuck. I found out that the drawing can be corrected. Hereinafter, it demonstrates using drawing.

  First, when drawing an EUV mask, measurement is performed as follows before drawing job registration. That is, the three-dimensional shape of the back surface of the EUV mask substrate is previously excluded from the influence of the mask weight, and only the shape of the back surface unique to the substrate is measured by the flatness measuring instrument. Furthermore, a high-precision measuring device using an interferometer that cannot be incorporated into the drawing device is used for measurement. Thereby, the shape of the mask back surface can be accurately measured.

FIG. 6 is a conceptual diagram for explaining a method of measuring the three-dimensional shape of the back surface of the substrate with the flatness measuring instrument in the first embodiment.
First, in order to measure the three-dimensional shape of the back surface of the substrate before drawing job registration, for example, the substrate to be the sample 101 as shown in FIG. 6 is placed on the base 520 in a vertical state. Then, the entire opposing surface is measured using the interferometer 510 using the interference principle. Thereby, it is possible to measure with high accuracy. As a result, it is possible to measure only the shape of the back surface unique to the substrate with good reproducibility while eliminating the influence of the weight of the mask substrate.

  Based on the measured back surface shape information unique to the substrate, the amount of pattern misalignment is calculated. Then, the misregistration amount obtained as one of the parameters specific to the board at the time of drawing registration is read. Then, the coordinate system of the drawing pattern is converted based on the obtained positional deviation amount. Thereby, the position of the drawing pattern can be corrected so that the pattern is drawn in the coordinate system when it is chucked on an ideal plane. That is, the positional deviation amount can be corrected. As a substrate holding method, a mechanical three-point holding method capable of holding a substrate with high reproducibility is used as an already established technique.

FIG. 7 is a diagram illustrating an example of a three-dimensional shape of the back surface of the substrate in the first embodiment.
As shown in FIG. 7, it can be seen that the back surface of the substrate has not only a deflection due to its own weight but also a unique shape due to imperfections in the polishing process of the surface.

  Then, as a recent calculation step, the drawing apparatus inputs shape distribution data such as a height distribution on the back surface of the substrate measured by the flatness measuring instrument. Then, the shape distribution data of the back surface of the substrate, which becomes the back surface shape information unique to the substrate, is fitted (approximated) with a fourth-order polynomial, for example.

  Then, as an inclination calculation step, a local inclination is obtained from the differential value of the approximated fourth-order polynomial.

Next, as a positional deviation amount calculation step, based on the three-dimensional shape of the back surface of the substrate, the positional displacement amount of the pattern when the pattern is drawn on the surface of the substrate when the back surface of the substrate is corrected to a flat surface (first positional deviation) (Quantity).
FIG. 8 is a diagram showing an example of a fitted three-dimensional shape of the back surface of the substrate in the first embodiment.
The three-dimensional shape distribution on the back surface of the substrate shown in FIG. 7 is fitted with a fourth-order polynomial. Further, partial differentiation is performed for X and Y which are orthogonal to each other. As a result, a local gradient distribution in the X and Y directions is obtained. FIG. 8 shows the obtained distribution.

FIG. 9 is a conceptual diagram for explaining a method of calculating a positional deviation amount in the first embodiment.
In FIG. 9, a local part is extracted and described. The thickness of the substrate to be the sample 101 is T, and the neutral surface without expansion / contraction is defined as the central surface of the substrate. At this time, when the local inclination θ is obtained by the inclination calculation unit 454, if the back surface is corrected to a flat surface as in the case where the back surface is chucked with an electrostatic chuck, the corresponding positional deviation δ (x, y) on the substrate surface. ) Will occur. However, when the mask is in close contact with the electrostatic chuck, a frictional force is generated between the mask and the electrostatic chuck, so the neutral surface is not at the center of the substrate but from the balance of force to the electrostatic chuck surface side. There is a possibility of deviation. In that case, the pattern positional deviation amount δ on the mask surface can be obtained by multiplying the local inclination Δθ by the substrate thickness T and the proportional coefficient k. In this way, it is possible to obtain a distribution of pattern displacement when a pattern is drawn on the surface of the substrate to be the sample 101.

FIG. 10 is a diagram showing an example of the positional deviation amount distribution of the pattern on the surface of the substrate in the first embodiment.
As shown in FIG. 10, it is possible to obtain the distribution of the pattern position shift amount on the substrate surface that is generated only from the shape of the back surface unique to the substrate by the above-described calculation.

  Then, as a coefficient calculation step, a coefficient (first coefficient) of an approximate expression (first approximate expression) indicating a positional deviation correction amount for correcting the positional deviation amount is obtained based on the obtained positional deviation amount. Calculate. The approximate expression of the positional deviation correction amount in the first embodiment can be expressed by the following expressions (1-1) and (1-2).

Based on the positional deviation amount of the positional deviation amount distribution obtained in FIG. 10, a grid correction amount (positional deviation correction amount) drawn by cubic polynomial fitting is obtained. Then, the coefficients (a ₁₀ , a ₁₁ ,... A ₁₉ ) and the formula (1-2) shown in the formula (1-1) necessary when approximating the cubic polynomial in the X direction and the Y direction are approximated. The coefficients (b ₁₀ , b ₁₁ ,... B ₁₉ ) in the Y direction shown in FIG. If such a coefficient is used as a parameter, it is possible to correct the amount of misalignment based on the amount of deformation inherent to the substrate, excluding its own weight, in the drawing apparatus. The polynomial coefficient obtained here is added to the coefficient of the cubic polynomial used when normal back surface correction is not performed, as will be described later, and is used for drawing the corresponding substrate.

  Here, in the drawing apparatus, when holding the substrate by holding three points to clamp three places as will be described later, a positional deviation or XY stage at the time of pattern drawing caused by deformation caused by deflection of the sample 101 as a mask substrate due to its own weight. System-specific misalignment of the system, such as running error and mirror error for position measurement. Therefore, a coefficient (second coefficient) of an approximate expression (second approximate expression) indicating a position shift correction amount for correcting a position shift unique to the coordinate system of the system is prepared as a default value. The approximate expression of the positional deviation correction amount unique to this system can be expressed by the following expressions (2-1) and (2-2).

As described above, in the drawing apparatus, the EUV mask substrate to be the sample 101 is held in the horizontal direction by the three clamps without using the electrostatic chuck, so that the deformation due to the deflection of the sample 101 serving as the drawing mask substrate due to its own weight. Misalignment occurs when the pattern is drawn. In addition, the system-specific misalignment as described above occurs. Therefore, in order to correct such a positional deviation, a grid correction amount (a positional deviation correction amount) drawn by fitting the cubic polynomials of Formula (2-1) and Formula (2-2) is obtained in advance. Then, the coefficients (a _s0 , a _s1 ,..., A _s9 ) and the formula (2-2) shown in the formula (2-1) necessary when approximating the cubic polynomial in the X direction and the Y direction are approximated. The coefficients in the Y direction (b _s0 , b _s1 ,..., B _s9 ) shown in FIG. A coefficient (second coefficient) of the approximate expression (second approximate expression) indicating the amount of misalignment correction is stored as a default value.

  As described above, the approximate expressions shown in Expression (2-1) and Expression (2-2) are based on the pattern displacement amount (second) when the pattern is drawn on the surface of the substrate without correcting the back surface of the substrate to a flat surface. The positional deviation correction amount for correcting the positional deviation amount).

  Then, as the adding step, using the coefficient (second coefficient) of the approximate expression (second approximate expression) shown in Expression (2-1) and Expression (2-2), the first coefficient is added to the second coefficient. Add coefficients. The approximate expression of the positional deviation correction amount after the addition can be expressed by the following expressions (3-1) and (3-2).

By adding the coefficients of the third-order polynomial according to the approximate expressions shown in Expressions (3-1) and (3-2), the positional deviation correction amount inherent to the substrate, which excludes its own weight from the positional deviation correction amount inherent to the system, is obtained. In addition, a misregistration correction amount can be obtained.
In the first embodiment, a case where a cubic polynomial is used as an approximate expression indicating the amount of misalignment correction for correcting the misalignment inherent in the coordinate system of the system of the electron beam drawing apparatus is taken as an example. However, a polynomial having an order of 4th order or higher may be used. At that time, a polynomial for fitting a three-dimensional shape distribution representing the back surface shape of the EUV mask in accordance with the order of the approximate expression indicating the positional deviation correction amount for correcting the positional deviation amount inherent in the coordinate system of the drawing apparatus system. Is approximated by a quintic polynomial when the approximate expression indicating the positional deviation correction amount for correcting the positional deviation correction amount for correcting the positional deviation amount inherent in the coordinate system of the drawing apparatus system is a quartic polynomial. Is preferred.

FIG. 11 is a conceptual diagram illustrating a configuration of the drawing apparatus according to the first embodiment.
In FIG. 11, a variable shaping type EB drawing apparatus 100, which is an example of a charged particle beam drawing apparatus, includes an electron column 102, a drawing chamber 103, an XY stage 105, an electron gun 201, an illumination lens 202, a 1 aperture 203, projection lens 204, deflector 205, second aperture 206, objective lens 207, and deflector 208, and a drawing data processing circuit 322, deflection control circuit 320, calculator 450, memory 462, as control units A memory 324 and a hard disk (HD) device 326 as an example of a magnetic disk device are provided. A deflection control circuit 320, a computer 450, a memory 324, and an HD device 326 are connected to the drawing data processing circuit 322. In addition, a memory 462 is connected to the computer 450. The HD device 326 stores the coefficients of the approximate expressions (2-1) and (2-2) as the default value 328 described above. Approximation formulas (2-1) and (2-2) are not shown in the drawing because of a positional deviation when a pattern is drawn due to deformation caused by deflection due to the weight of the sample 101, which is a mask substrate, and the running of the XY stage 105. A positional deviation correction amount for correcting a positional deviation inherent in the coordinate system of the system such as a mirror error for position measurement is shown.

  In the electron barrel 102, an electron gun 201, an illumination lens 202, a first aperture 203, a projection lens 204, a deflector 205, a second aperture 206, an objective lens 207, and a deflector 208 are arranged. . An XY stage 105 is arranged in the drawing chamber 103. On the XY stage 105, the sample 101 is sandwiched and held at three positions by a clamp 210. An alignment chamber 104 is connected to the drawing chamber 103, and alignment (positioning) and constant temperature processing of the sample 101 are performed before being transferred to the drawing chamber 103.

  Within the computer 450, there are various functions such as a recent calculation unit 452, a tilt calculation unit 454, a positional deviation amount calculation unit 456, a coefficient calculation unit 458, and an addition unit 460. The computer 450 receives shape distribution data on the back surface of the mask from the flatness measuring device 500 serving as an external device. The drawing data processing circuit 322 receives information including data indicating whether it is for EUV mask or a normal light mask other than EUV.

  In FIG. 11, the components necessary for explaining the first embodiment are described. For the variable shaping type EB drawing apparatus 100, other necessary configurations may be included. In FIG. 11, the computer 450, which is an example of a computer, executes processing of each function such as a recent calculation unit 452, a tilt calculation unit 454, a positional deviation amount calculation unit 456, a coefficient calculation unit 458, and an addition unit 460. However, this is not a limitation. You may implement by the hardware by an electric circuit. Alternatively, it may be implemented by a combination of hardware and software. Alternatively, a combination of such hardware and firmware may be used.

  An electron beam 200 that is an example of a charged particle beam emitted from the electron gun 201 illuminates the entire first aperture 203 having a rectangular hole, for example, a rectangular hole, by an illumination lens 202. Here, the electron beam 200 is first formed into a rectangle, for example, a rectangle. Then, the electron beam 200 of the first aperture image that has passed through the first aperture 203 is projected onto the second aperture 206 by the projection lens 204. The position of the first aperture image on the second aperture 206 is controlled by the deflector 205. Thereby, a beam shape and a dimension can be changed. Then, the electron beam 200 of the second aperture image that has passed through the second aperture 206 is focused by the objective lens 207. On the other hand, the light is deflected by the deflector 208. And it irradiates the desired position of the sample 101 on the XY stage 105 arrange | positioned so that a movement is possible. The deflection voltage of the deflector 208 is controlled by the deflection control circuit 320.

FIG. 12 is a conceptual diagram illustrating an example of a substrate holding state in the first embodiment.
As shown in FIG. 12, on the XY stage 105, three places of the sample 101 serving as a substrate are clamped and held by a clamp 210.
FIG. 13 is a conceptual cross-sectional view showing an example of a state of substrate holding in the first embodiment.
The clamp 210 includes an upper surface reference piece 212 and a clamp pin 214. The same axis is clamped and clamped from above and below by point contact with the upper surface reference piece 212 from the front surface side of the sample 101 and with the clamp pin 214 from the rear surface side of the sample 101. By clamping the sample 101 at three locations, the contact with the substrate is limited to a minimum location, and particle collection like an electrostatic chuck can be prevented. Therefore, the cleanliness of the clamp point can be maintained. In addition, by holding at three points on the back surface of the substrate, it is possible to make it less susceptible to errors on the back surface of the substrate than in the case of holding the surface like an electrostatic chuck. As a result, errors are small and reproducibility is excellent.

  However, when the EUV mask is the sample 101, if a pattern is drawn on the sample 101 in such a state, the back surface of the substrate is corrected to a flat surface as in the case of chucking with an electrostatic chuck specified by the SEMI standard. Absent. For this reason, if the sample 101 applied to the exposure apparatus chucked by the electrostatic chuck is used as a mask, the position of the pattern exposed on the wafer or the like is shifted. For example, when the size of the substrate serving as the sample 101 is 152.4 mm square, an electrostatic chuck chucks at least a 142 mm square region in the center. That is, an area of at least 142 mm square in the central portion on the back surface of the substrate is corrected to a flat surface. Therefore, when the correction positional deviation amount is calculated as described above and a pattern added to the default value is used as a parameter, a pattern is drawn on the sample 101, or the chuck is chucked by an electrostatic chuck specified by the SEMI standard. The position where the electron beam 200 is irradiated can be corrected so that a pattern is drawn at a predetermined position with the back surface of the substrate corrected to a flat surface.

  Processing of each function such as the recent calculation unit 452, the inclination calculation unit 454, the positional deviation amount calculation unit 456, the coefficient calculation unit 458, and the addition unit 460 will be described below.

  First, as the above-described recent calculation process, the computer 450 inputs shape distribution data such as the height distribution of the back surface of the substrate measured by the flatness measuring device. The input shape distribution data may be stored in the memory 462. Then, the recent calculation unit 452 reads the shape distribution data of the back surface of the substrate, which is the back surface shape information unique to the substrate, from the memory 462, and fits (approximates) the shape distribution with, for example, a fourth-order polynomial.

  Next, as the above-described gradient calculation step, the gradient calculation unit 454 obtains a local gradient from the approximated differential value of the fourth-order polynomial.

  Next, as the above-described misregistration amount calculation step, the misregistration amount calculation unit 456 is configured to draw a pattern on the front surface of the substrate when the back surface of the substrate is corrected to a flat surface based on the three-dimensional shape of the back surface of the substrate. Is calculated (first positional deviation amount).

  Next, as the coefficient calculation step described above, the coefficient calculation unit 458 is an approximate expression (first approximate expression) indicating a position shift correction amount for correcting the position shift amount based on the obtained position shift amount. The first coefficient is calculated.

  Next, as the addition step described above, the adding unit 460 adds the expression (1-1) and the expression (1) to the coefficient (second coefficient) of the approximate expression indicated by the expressions (2-1) and (2-2). The first coefficient of the approximate expression shown in -2) is added. As described above, the approximate expression (second approximate expression) represented by Expression (2-1) and Expression (2-2) is obtained when a pattern is drawn on the surface of the substrate without correcting the back surface of the substrate to a plane. A misregistration correction amount for correcting the pattern misregistration amount (second misregistration amount) is shown. The coefficient parameter serving as the second coefficient is stored in the HD device 326 as the default value 328 of the drawing device. Therefore, the addition unit 460 reads the default value 328 from the HD device 326 via the drawing data processing circuit 322, and adds the coefficient (first coefficient) obtained by the coefficient calculation unit 458.

  Then, as the drawing step, the drawing unit 150 approximates Expression (3-1) and Expression (3-2) indicating the amount of misalignment correction using the added value (third coefficient) obtained as a result of the addition. A pattern is drawn on the surface of the substrate to be the sample 101 using the electron beam 200 based on the positional deviation correction amount obtained by the equation (third approximate equation). That is, the drawing data processing circuit 322 outputs information on the positional deviation correction amount obtained by the approximate expression indicating the positional deviation correction amount using the coefficient obtained as a result of the addition to the deflection control circuit 320. A deflection voltage controlled by the deflection control circuit 320 is applied to the deflector 208 to deflect the electron beam 200 and irradiate a predetermined position.

FIG. 14 is a diagram illustrating an example of a positional deviation correction amount distribution for correcting deformation when the weight of the first embodiment is excluded.
FIG. 15 is a diagram showing an example of the pattern position distribution of the EUV mask drawn by performing the positional deviation correction in the first embodiment.
16 is a diagram showing a distribution obtained by subtracting the distribution shown in FIG. 14 from the distribution shown in FIG.
As shown in FIG. 16, since the distribution is not widened or narrowed, it has a shape close to a square. Therefore, the predicted misregistration correction amount shown in FIG. Is effective.

  As described above, by adding the coefficient (first coefficient) obtained by the coefficient calculation unit 458 to the default value 328, even when drawing is performed without using the electrostatic chuck, the electrostatic chuck is used. It is possible to correct the position. In other words, even if the EUV mask substrate serving as the sample 101 is held in the horizontal direction by the three clamps 210 and is drawn by the variable shaping type EB drawing apparatus 100, the position is corrected when the electrostatic chuck is used. be able to.

  As described above, the inventors have found that the drawing apparatus can correct the position when the electrostatic chuck is used without using the electrostatic chuck. Therefore, the position measurement apparatus according to the first embodiment evaluates the position accuracy of the drawing apparatus and the position accuracy of the pattern shape on the wafer held by the electrostatic chuck in the exposure apparatus.

  In such a position measuring apparatus, when a position assumed when the pattern provided on the EUV mask is transferred onto the wafer is measured, a vacuum chuck is selectively used for measurement, and the EUV mask is drawn. When measuring the position of a pattern drawn for the purpose of state management and drawing accuracy management of the drawing apparatus to be used, measurement is performed by selectively using a normal three-point support method.

  The operation of the position measurement apparatus 600 when measuring the position assumed when the pattern provided on the EUV mask is transferred onto the wafer will be described. First, the transfer robot 640 uses the hand 642 to carry out the second set by the vacuum chuck described above from the holder 650 and transfer it onto the stage 620. Then, the second set is placed on the stage 620. Then, with the vacuum chuck member 240 placed on the stage 620, the vacuum chuck member 240 is evacuated and sucked by the vacuum pump 680 via the stage 620. Thereby, the sample 101 placed on the vacuum chuck member 240 is sucked through the vacuum chuck member 240, and is sucked and chucked by the vacuum chuck member 240. In this state, the pattern provided on the EUV mask is recognized and imaged by the pattern position recognition unit 610 while the stage 620 is moved in the X and Y directions by the stage control circuit 674. Then, the captured image is sent to the computer 660 together with position information controlled by the position control system 622. Then, the position of the pattern provided on the EUV mask is measured from the captured image and position information. By measuring the position of the pattern provided on the EUV mask, the amount of displacement from the desired position can be measured under the same conditions as when chucking with an electrostatic chuck.

  Next, the operation of the position measurement apparatus 600 when measuring the position of a pattern drawn for the purpose of state management and drawing accuracy management of a drawing apparatus that draws an EUV mask will be described. The transport robot 640 uses the hand 642 to carry out the first set supported by three points from the holder 650 and transport it onto the stage 620. Then, the first set is placed on the stage 620. In the three-point support member 220, the sample 101 is simply placed on the three-point support member 220, and in this state, the stage 620 is moved in the XY direction by the stage control circuit 674 while the pattern position recognition unit 610 uses it for EUV. The pattern provided on the mask is recognized and imaged. Then, the captured image is sent to the computer 660 together with position information controlled by the position control system 622. Then, the position of the pattern provided on the EUV mask is measured from the captured image and position information. If the pattern provided on the EUV mask is drawn without correction of the back surface shape for the purpose of state management and drawing accuracy management of the drawing apparatus, the position of the pattern is measured, so that the variable forming EB drawing is performed. When three places are clamped by the clamp 210 of the apparatus 100, the amount of positional deviation from the desired position can be measured. That is, the accuracy of the drawing apparatus can be evaluated here.

  As described above, by arranging the three-point support member 220 and the vacuum chuck member 240 on the holder 650, a substrate holding member to be used on the stage 620 can be selected. When the vacuum chuck member 240 is selected, the substrate can be vacuum chucked by evacuating and sucking the back surface of the substrate through the vacuum chuck member 240 by the vacuum pump 680. The pattern position recognition unit 610 can recognize the position of the pattern formed on the substrate held on the selected one of the three-point support member 220 and the vacuum chuck member 240.

  As described above, when evaluating the positional accuracy assumed when the pattern provided on the EUV mask is transferred onto the wafer, the back surface shape correction performed in the drawing apparatus can be performed by using a vacuum chuck. It can be evaluated whether it is functioning correctly. In addition, by using a normal three-point support method that is excellent in reproducibility of substrate holding and has a low risk of adhesion of foreign matter, it is possible to determine whether or not the drawing is performed in accordance with the back surface shape correction performed in the drawing apparatus. It can be measured under the same holding conditions. As a result, the accuracy of the mask drawing apparatus for drawing the EUV mask can be evaluated.

Further, as a positional deviation amount measuring method, it is also preferable to selectively use a vacuum chuck and a three-point support method selectively for a pattern subjected to back surface shape correction and a pattern not performed.
In other words, as the first positional deviation amount measuring step, the substrate back surface is held by the electrostatic chuck specified by the SEMI standard based on the three-dimensional shape of the back surface of the substrate when the influence of its own weight is excluded. A first pattern drawn by correcting a positional deviation amount of a pattern predicted when a pattern is drawn on the front surface of the substrate when the back surface is corrected to a flat surface is vacuum-chucked to the first pattern. The positional deviation amount of the pattern is measured.

  Then, as the second misregistration amount measuring step, the second pattern drawn by correcting the misregistration amount of the pattern predicted when the pattern is drawn on the front surface of the substrate without correcting the back surface of the substrate to a flat surface. Is used to measure the amount of displacement of the second pattern while supporting the back surface of the substrate at three points.

  By measuring as described above, whether or not the pattern is drawn at the same position as when the back surface of the substrate is corrected to a flat surface as in the case of being held by the electrostatic chuck defined by the SEMI standard is vacuum chucked. Can be confirmed. As a result, it is possible to confirm the validity of the correction amount corrected in the state of being kept clean while being held in the same manner as when held by the electrostatic chuck. On the other hand, whether or not a pattern is drawn at a desired position when the back surface of the substrate is not corrected to a flat surface as in the case where the back surface of the substrate is supported and held at three points without using the electrostatic chuck specified by the SEMI standard. Can be confirmed. As a result, it is possible to confirm the validity of the above-described default value coefficient, which is a positional deviation correction amount unique to the drawing apparatus. As described above, it is possible to confirm the positional accuracy of both the corrected pattern and the uncorrected pattern assuming the case of holding by the electrostatic chuck.

  Here, as the material of the vacuum chuck member 240, it is desirable to use a material harder than the material used for the electrostatic chuck member defined by the SEMI standard, for example, a SiC (silicon carbide) material. That is, the SEMI standard (SEMI P40-1103) stipulates that a low thermal expansion material be used as the electrostatic chuck material. For example, it is known to use zero-dur which is a low thermal expansion glass ceramic material. By using a material harder than this material, the amount of deformation when the sample 101 is chucked can be made smaller than when the sample 101 is chucked by an electrostatic chuck. Since the amount of deformation can be reduced, the back surface of the substrate can always be brought close to an ideal planar shape in a chucked state, and reproducibility can be improved as compared with the case of chucking with an electrostatic chuck.

As described above, according to the present embodiment, it is possible to confirm the positional deviation of the pattern drawn by the drawing apparatus that does not use the electrostatic chuck by three-point support, and assume that the pattern is held by the electrostatic chuck. It is also possible to confirm the pattern position deviation of the corrected pattern. Further, Ru can see the pattern position shift without using the electrostatic chuck. Therefore, the reproducibility of position measurement can be improved as compared with the case where an electrostatic chuck is used.

Embodiment 2. FIG.
FIG. 17 is a conceptual diagram showing the configuration of the position measurement apparatus according to the second embodiment.
In FIG. 17, a position measurement apparatus 600 includes a housing 602, a pattern position recognition unit 610, a stage 620, a position control system 622, a surface plate 630, a transfer robot 640, a holder 650 as an example of an arrangement unit, a robot control circuit 646, A computer 660, a memory 662, a vacuum pump 680, a stage control circuit 674, and a pressure control device 681 are provided. 1 except that a pressure control device 681 is installed on the primary side of the vacuum pump 680, that is, on the intake port side. The pressure control device 681 includes a pressure sensor 683 and a flow rate sensor 685.

  A pressure control device 681 as an example of a control device controls the suction force of the vacuum pump 680. For example, it can be adjusted by the opening / closing angle of the valve. The pressure sensor 683 measures the pressure on the primary side of the pressure control device 681, that is, the pressure on the vacuum chuck side. Further, the flow rate sucked by the vacuum pump 680 is measured by the flow rate sensor 685. By controlling the suction force of the vacuum pump 680 and adjusting the suction force of the back surface of the substrate serving as the sample 101, deformation of the back surface of the substrate due to excessive suction can be suppressed. As a result, the back surface of the substrate can be brought closer to an ideal plane.

Embodiment 3 FIG.
FIG. 18 is a conceptual diagram showing the configuration of the position measurement apparatus according to the third embodiment.
In FIG. 18, a position measurement apparatus 600 includes a housing 602, a pattern position recognition unit 610, a stage 620, a position control system 622, a surface plate 630, a transfer robot 640, a holder 650 as an example of an arrangement unit, a robot control circuit 646, A computer 660, a memory 662, a vacuum pump 680, and a stage control circuit 674 are provided. 18 is the same as FIG. 1 except that an identification mark 241 is provided on the vacuum chuck member 240.

  When a plurality of holding members, in particular, a plurality of vacuum chuck members 240 are stored in the holder 650 serving as an arrangement portion, each vacuum chuck member 240 can be identified by the identification mark 241.

  Here, the chuck surface of the electrostatic chuck member used in the exposure apparatus is not necessarily formed in an ideal plane. When the sample 101 is chucked by the chuck surface of the electrostatic chuck member deviated from the plane, the surface of the substrate serving as the sample 101 receives the influence of the shape of the chuck surface of the electrostatic chuck member, and is deformed accordingly. Therefore, when there are a plurality of electrostatic chuck members to be used, the vacuum chuck members 240 are manufactured according to the shape of the chuck surface of each electrostatic chuck member. If each vacuum chuck member 240 can be identified by the identification mark 241, the pattern position can be measured based on the chuck surface of the electrostatic chuck member.

Embodiment 4 FIG.
Since the vacuum chuck member 240 in each of the above-described embodiments has a high planar accuracy of the suction surface, even if it is intended to remove the substrate serving as the sample 101, it is difficult to remove. In the fourth embodiment, a configuration in which the substrate can be easily removed will be described.

FIG. 19 is a conceptual diagram illustrating a configuration of the position measurement apparatus according to the fourth embodiment.
19, the position measurement apparatus 600 further includes a compressor 682, valves 684, 686, a valve control circuit 688, an intake line 694, and a filter 676 as an example of a gas supply unit in addition to the configuration of FIG. . A vacuum chuck member 252 is disposed on the holder 650. 19 is the same as FIG. 1 except that a compressor 682, valves 684 and 686, a valve control circuit 688, an intake line 694, and a filter 676 are provided, and the vacuum chuck member 240 is replaced with a vacuum chuck member 252. is there. In FIG. 19, the valve 684 is disposed in the middle of the exhaust line 692 connected from the stage 620 to the vacuum pump 680. On the other hand, the valve 686 is disposed in the middle of the intake line 694 connected from the compressor 682 to the stage 620. The valve 684 opens and closes the exhaust line 692. The valve 686 opens and closes the intake line 694. The valves 684 and 686 are controlled by a valve control circuit 688. The filter 676 is disposed in the middle of the intake line 694 connected from the compressor 682 to the stage 620. Here, it is arranged on the secondary side of the valve 686, but it may be on the primary side. Further, the control portions of the valve control circuit 688 and the compressor 682 are connected to a computer 660, and both are controlled by the computer 660. In addition, inside the stage 620, a cavity (not shown) is formed that connects the exhaust line 692 to the exhaust line of the vacuum chuck member 252 when the vacuum chuck member 252 is disposed. Similarly, inside the stage 620, a cavity (not shown) is formed that connects from the suction line 694 to the suction line of the vacuum chuck member 252 when the vacuum chuck member 252 is disposed.

FIG. 20 is a conceptual diagram showing an example of a cross section of the vacuum chuck member in the fourth embodiment.
As shown in FIG. 20, the contact surface 244 is formed in the vacuum chuck member 252 at a predetermined pitch defined in the SEMI standard with the same shape and area as the electrostatic chuck attracting portion 232 shown in FIG. The chuck is sucked by the vacuum pump 680 through a flow path 262 serving as an exhaust line through a buffer 243 in a sealed space formed in the vacuum chuck member 252 with a portion serving as an opening serving as a suction section 242. The Although not shown here, the vacuum pump 680 sucks the substrate serving as the sample 101 through the stage 620 and the vacuum chuck member 252 in a state where the vacuum chuck member 252 is placed on the stage 620. In this way, the sample 101 is adsorbed on the contact surface 244. In addition to the flow path 262, the buffer 243 has a flow path 264 serving as an intake line. The flow path 264 is connected to the compressor 682 via a filter 676 and a valve 686. Although not shown here, the compressor 682 supplies a gas to the substrate serving as the sample 101 through the stage 620 and the vacuum chuck member 252 with the vacuum chuck member 252 placed on the stage 620. Therefore, the inside of the buffer 243 can be in a vacuum state or a pressurized state by the configuration of FIGS. 19 and 20.

Further, even if the inside of the buffer 243 serving as the partial sealed space described above becomes a negative pressure by being evacuated by the vacuum pump 680, or clean nitrogen (N ₂ ) or air is supplied by the compressor 682. Even if it becomes positive pressure, it has a structure that can maintain hermeticity if there is no gap in the chuck portion. Impurities in the gas can be removed by the filter 676. As described above, since the contact surface 244 has a high planar accuracy, it is difficult to remove the contact surface 244 even if an attempt is made to remove the substrate after it is once adsorbed. Therefore, when the substrate is peeled from the vacuum chuck member 252, the position measuring device 600 uses a gas such as nitrogen (N ₂ ) or air to control the suction surface of the vacuum chuck member to be higher than the external pressure. As a result, the substrate can be easily peeled off.

  Further, the position measuring device 600 discharges gas to the outside of the buffer 243 (inside the housing 602 of the device) by the compressor 682 through the vacuum chuck member 252 in a state where the substrate is not vacuum chucked by the vacuum chuck member 252. To control. When the substrate is not placed on the contact surface 244 of the vacuum chuck member 252, it is possible to keep the substrate adsorption surface clean by constantly flowing clean nitrogen or air from the suction part 242 of the contact surface 244. Further, when the vacuum chuck member 252 on which the substrate is not placed is disposed on the stage 620 and the substrate is placed on the contact surface 244 of the vacuum chuck member 252 from the state, the impact when the substrate is placed is affected. It can be relaxed by the pressure of clean nitrogen or air generated by constantly flowing.

  The vacuum chuck member 252 has a sensor 246 that detects the position of the substrate. This sensor 246 is a proximity sensor, and is preferably embedded in the central portion of the suction surface. Then, the output signal of the sensor 246 is transmitted to the computer 660. By measuring the distance between the suction surface and the substrate by the sensor 246, it is possible to detect whether or not the substrate is in contact with the suction surface. As this sensor 246, for example, a capacitance type sensor or an optical sensor for detecting light reflected on the back surface of the substrate is suitable. By using these sensors, it is possible to detect the position of a non-metallic quartz substrate or a substrate whose main component is low thermal expansion glass with high accuracy. Further, if the substrate is in contact with or not in contact with the substrate, for example, if the substrate back surface flatness required for the EUV mask is 50 nm or less, it may be determined that the substrate is in contact with the suction surface. .

  Whether or not the substrate is vacuum chucked by the vacuum chuck member 252 may be determined by the output signal of the sensor 246. Further, the supply amount and supply pressure of the gas supplied into the buffer 243 when the substrate is peeled off from the vacuum chuck member 252, and the supply amount and supply pressure of the gas supplied when the substrate is not vacuum chucked to the vacuum chuck member 252. May be the same or different.

Embodiment 5. FIG.
In the fifth embodiment, a configuration in which the substrate can be attracted to the vacuum chuck member with a plane with higher accuracy than the above-described embodiments will be described.

FIG. 21 is a conceptual diagram showing the configuration of the position measurement apparatus according to the fifth embodiment.
In FIG. 21, the position measuring device 600 further includes valves 685, 687, an intake line 695, a filter 678, and an exhaust line 693 in addition to the configuration of FIG. 19. A vacuum chuck member 254 is disposed on the holder 650. 21 is the same as FIG. 19 except that valves 685 and 687, an intake line 695, a filter 678, and an exhaust line 693 are provided, and that the vacuum chuck member 252 is replaced with a vacuum chuck member 254. In FIG. 21, the valve 685 is disposed in the middle of the exhaust line 693 connected from the stage 620 to the vacuum pump 680. Further, the exhaust line 693 and the exhaust line 692 are finally connected and connected to the vacuum pump 680. On the other hand, the valve 687 is arranged in the middle of an intake line 695 connected from the compressor 682 to the stage 620. The intake line 694 and the intake line 695 are connected to and connected to the compressor 682. The valve 685 opens and closes the exhaust line 693. The valve 687 opens and closes the intake line 695. The valves 685 and 687 are controlled by a valve control circuit 688 in the same manner as the valves 684 and 686. The filter 678 is disposed in the middle of the intake line 695 connected from the compressor 682 to the stage 620. Here, it is arranged on the secondary side of the valve 687, but it may be on the primary side. Impurities in the gas supplied from the compressor 682 can be removed by the filter 676 and the filter 678.

  Further, in the stage 620, a first exhaust cavity (not shown) connected to the exhaust line of the vacuum chuck member 254 from the exhaust line 692 when the vacuum chuck member 254 is disposed is formed. Furthermore, a second exhaust cavity (not shown) that connects the exhaust line 693 to the exhaust line of the vacuum chuck member 254 when the vacuum chuck member 254 is disposed is formed inside the stage 620. Similarly, a first suction cavity (not shown) that connects from the suction line 694 to the suction line 694 of the vacuum chuck member 254 when the vacuum chuck member 252 is disposed is formed inside the stage 620. Furthermore, a second suction cavity (not shown) that connects from the suction line 695 to the suction line of the vacuum chuck member 254 when the vacuum chuck member 254 is disposed is formed inside the stage 620.

FIG. 22 is a conceptual diagram showing an example of a cross section of the vacuum chuck member in the fifth embodiment.
FIG. 23 is a conceptual diagram showing an example of the upper surface of the vacuum chuck member in the fifth embodiment.
22 and 23, the vacuum chuck member 254 is formed in a buffer 243 connected to the suction part 242 provided in the center of the contact surface 244 and a buffer 245 connected to the suction part 242 provided in the periphery thereof. Divided sealed space. 22 and 23, a buffer 243 indicated by A is provided with a flow path 264 and a flow path 262. 22 and 23, the buffer 245 indicated by B is provided with a channel 265 and a channel 263. The exhaust line 692 is connected to the flow path 262 via the stage 620. An exhaust line 693 is connected to the flow path 263 via the stage 620. An intake line 694 is connected to the flow path 264 via a stage 620. An intake line 695 is connected to the flow path 265 via a stage 620.

  Further, the vacuum chuck member 254 is provided with a sensor 246 embedded in a central portion of the suction surface and a sensor 247 embedded in a peripheral portion of the suction surface. Both sensors are proximity sensors that detect the position of the substrate. Similar to the sensor 246, the output signal of the sensor 247 is transmitted to the computer 660. By measuring the distance between the suction surface and the substrate by the sensor 246, it is possible to detect whether or not the substrate in the central portion is in contact with the suction surface. By measuring the distance between the suction surface and the substrate by the sensor 247, it is possible to detect whether or not the substrate in the peripheral portion is in contact with the suction surface. Similarly to the sensor 246, the sensor 247 is preferably, for example, a capacitive sensor or an optical sensor that detects light reflected on the back surface of the substrate. Others are the same as FIG.

  In the chucking method, a substrate to be the sample 101 is sucked by a vacuum pump 680 from a plurality of suction portions 242 provided at the center of the contact surface 244 through a buffer 243 and a flow path 262 serving as an exhaust line. In this way, the central portion of the sample 101 is adsorbed on the contact surface 244. Further, the substrate is sucked by the vacuum pump 680 from the plurality of suction portions 242 provided in the peripheral portion of the contact surface 244 through the buffer 245 and the flow path 263 serving as an exhaust line. In this way, the peripheral portion of the sample 101 is adsorbed on the contact surface 244. As described above, the vacuum chuck member 254 includes the first suction mechanism that sucks the center portion of the back surface and the second suction mechanism that sucks the peripheral portion of the center portion when the back surface of the substrate is vacuum chucked. Yes.

  In addition, the compressor 682 supplies gas to the sample 101 through the stage 620 and the buffer 243 while the vacuum chuck member 254 is placed on the stage 620. As a result, gas is supplied to the central portion of the sample 101 from the plurality of suction portions 242 provided in the central portion of the contact surface 244. Similarly, the compressor 682 supplies gas to the sample 101 through the stage 620 and the buffer 245. As a result, gas is supplied to the peripheral portion of the sample 101 from the plurality of suction portions 242 provided in the peripheral portion of the contact surface 244. Therefore, the inside of the buffer 243 and the buffer 245 can be in a vacuum state or a pressurized state by the configuration of FIGS.

  Next, a procedure for sucking and removing the substrate will be described. First, based on information from the sensors 246 and 247, when the substrate is not placed on the suction surface, the valve 686 and the valve 687 are opened, and clean nitrogen or air is allowed to flow from the suction unit 242 through the intake lines 694 and 695. Thereby, the deposit | attachment to an adsorption | suction surface can be suppressed. Therefore, the contact surface 244 can be kept clean. At this time, the valve 684 and the valve 685 are closed.

  When the sensor 246 or the sensor 247 detects that the substrate is placed on the suction surface, the valve 686 and the valve 687 are first closed. Subsequently, by opening the valve 684, the buffer 243 in the central portion is evacuated through the exhaust line 692. As a result, the central portion of the substrate can be adsorbed to the contact surface 244. After confirming that the central portion is adsorbed by the sensor 246, the valve 685 is opened, and the buffer 245 in the peripheral portion is evacuated through the exhaust line 693. As a result, the peripheral portion of the substrate can be adsorbed to the contact surface 244. Then, it is confirmed by the sensor 247 that the peripheral portion has been adsorbed. As described above, when vacuum-chucking the back surface of the substrate, the peripheral portion is sucked by the above-described second suction mechanism after the central portion of the back surface is sucked by the above-described first suction mechanism. As described above, in the fifth embodiment, the structure is such that the chucking force can be independently generated at the central portion and the peripheral portion.

  Here, the substrate to be adsorbed has a convex shape on the surface side due to the multilayer film provided on the surface, and there is a gap of about 1 micron between the adsorption surface and the central portion. Therefore, in order to adsorb the substrate to the adsorption surface with a gap of 50 nm or less, which is the flatness specification value of the EUV exposure mask, it is necessary to first adsorb the central portion. This is because if the suction force is generated simultaneously on the entire surface of the suction surface, the contacting peripheral portion is first suctioned. For this reason, when the central portion is attracted, it becomes necessary to overcome the attracting force and frictional force of the peripheral portion. Therefore, in order to chuck with a highly accurate plane, it is desirable to control so that the central portion is first sucked.

  Here, in order to control the central portion to be adsorbed first, it is desirable that the area of the central portion is as small as possible. However, since the chucking force is proportional to the area if the exhaust capacity of the vacuum pump 680 is the same, the chucking force is divided so that the suction area of the central portion and the peripheral portion are the same so that the final suction force is uniform. It is desirable.

  Here, in FIG. 22 and FIG. 23, the buffer is divided into the central part and the peripheral part, but this is not restrictive. It may be divided into three or more. Even in a vacuum chuck in which the sealed space is divided into three or more, it is desirable that the suction surfaces connected to the sealed spaces are divided into the same area so that the final suction force is uniform.

  Further, when the back surface of the substrate is vacuum chucked, the first suction mechanism and the second suction mechanism may have different suction forces. For example, the force generated per generated unit area may be different. What is necessary is just to adjust the adsorption | suction area of a center part and a peripheral part so that final adsorption | suction power may become uniform.

  Further, as a result of the chucking operation, when the sensor 246 or the sensor 247 detects that the substrate is not attracted to the contact surface 244 serving as the attracting surface, the operation after the valve 686 and the valve 687 are closed is repeated. And effective.

  In the above description, the processing content or operation content described as “˜part” or “˜process” may be configured by a computer operable program. Or you may make it implement by not only the program used as software but the combination of hardware and software. Alternatively, a combination with firmware may be used. When configured by a program, the program is recorded on a recording medium such as a magnetic disk device, a magnetic tape device, an FD, or a ROM (Read Only Memory).

  Further, the computer 450 serving as a computer in FIG. 11 or the computer 660 serving as a computer in FIGS. 1, 17, 18, 19, and 21 further includes an example of a storage device via a bus (not shown). A random access memory (RAM), a ROM, a magnetic disk (HD) device, a keyboard (K / B) as an example of an input means, a mouse, a monitor as an example of an output means, a printer, or an example of an input output means It may be connected to an external interface (I / F), FD, DVD, CD or the like.

  The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. For example, the description of the control unit configuration for controlling the variable shaping type EB drawing apparatus 100 is omitted, but it is needless to say that the required control unit configuration is appropriately selected and used.

  In addition, all charged particle beam drawing methods, charged particle beam drawing apparatuses, misregistration amount measuring methods, and position measuring apparatuses that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention. The

1 is a conceptual diagram illustrating a configuration of a position measurement device according to Embodiment 1. FIG. 4 is a conceptual diagram illustrating an example of a configuration of a three-point support member in Embodiment 1. FIG. 4 is a conceptual diagram illustrating an example of a configuration of a vacuum chuck member in Embodiment 1. FIG. 3 is a conceptual diagram illustrating an example of a cross section of the electrostatic chuck according to Embodiment 1. FIG. FIG. 3 is a conceptual diagram showing an example of a cross section of the vacuum chuck in the first embodiment. FIG. 3 is a conceptual diagram for explaining a method for measuring a three-dimensional shape of a back surface of a substrate with the flatness measuring instrument in the first embodiment. 4 is a diagram illustrating an example of a three-dimensional shape of a substrate back surface in the first embodiment. FIG. FIG. 3 is a diagram showing an example of a fitted three-dimensional shape on the back surface of the substrate in the first embodiment. 6 is a conceptual diagram for explaining a method for calculating a positional deviation amount in the first embodiment. FIG. 6 is a diagram illustrating an example of a positional deviation amount distribution of a pattern on a surface of a substrate in Embodiment 1. FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. 3 is a conceptual diagram illustrating an example of a state of substrate holding in Embodiment 1. FIG. 4 is a conceptual cross-sectional view showing an example of a state of substrate holding in the first embodiment. FIG. 6 is a diagram illustrating an example of a positional deviation correction amount distribution for correcting deformation when the weight of the first embodiment is excluded. FIG. 6 is a diagram illustrating an example of a pattern position distribution of an EUV mask drawn by performing positional deviation correction in Embodiment 1. FIG. FIG. 16 is a diagram showing a distribution obtained by subtracting the distribution shown in FIG. 14 from the distribution shown in FIG. 15. FIG. 6 is a conceptual diagram illustrating a configuration of a position measurement device in a second embodiment. FIG. 9 is a conceptual diagram showing a configuration of a position measurement device in a third embodiment. FIG. 10 is a conceptual diagram illustrating a configuration of a position measurement device according to a fourth embodiment. 6 is a conceptual diagram showing an example of a cross section of a vacuum chuck member in Embodiment 4. FIG. FIG. 10 is a conceptual diagram showing a configuration of a position measurement device in a fifth embodiment. FIG. 10 is a conceptual diagram showing an example of a cross section of a vacuum chuck member in a fifth embodiment. FIG. 10 is a conceptual diagram illustrating an example of an upper surface of a vacuum chuck member in a fifth embodiment. It is a conceptual diagram for demonstrating operation | movement of the conventional variable shaping type | mold electron beam drawing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Variable shaping type EB drawing apparatus 101,340 Sample 102 Electron barrel 103 Drawing chamber 104 Alignment chamber 105 XY stage 150 Drawing unit 200 Electron beam 201 Electron gun 202 Illumination lens 203,410 First aperture 204 Projection lens 205,208 Deflection Instruments 206 and 420 Second aperture 207 Objective lens 210 Clamp 212 Upper surface reference piece 214 Clamp pin 220 Three-point support member 222 Support pin 230 Electrostatic chuck member 232 Suction unit 240 Vacuum chuck member 242 Suction unit 244 Contact surface 241 Mark 320 Deflection Control circuit 322 Drawing data processing circuit 324, 462 Memory 326 HD device 330 Electron beam 411 Opening 421 Variable shaping opening 430 Charged particle source 450 Computer 452 Recent operation unit 454 Inclination operation unit 456 Position shift amount calculation unit 458 Coefficient calculation unit 460 Addition unit 500 Flatness measuring device 510 Interferometer 520 Base 600 Position measurement device 602 Case 610 Pattern position recognition unit 620 Stage 622 Position control system 630 Surface plate 640 Transport robot 642 Hand 644 Main body 646 Robot control circuit 650 Holder 660 Computer 662 Memory 674 Stage control circuit 680 Vacuum pump 681 Pressure control device 683 Pressure sensor 685 Flow rate sensor

Claims (9)

An arrangement portion for arranging a three-point support member for supporting the back surface of the mask substrate at three points, and a vacuum chuck member for vacuum chucking the back surface of the mask substrate;
A stage for placing one of the three-point support member and the vacuum chuck member arranged in the arrangement unit;
A vacuum pump for sucking the substrate through the vacuum chuck member in a state where the vacuum chuck member is placed on the stage;
A recognition unit for recognizing the position of the pattern formed on the substrate supported by the three-point support member placed on the stage and the position of the pattern formed on the substrate vacuum chucked by the vacuum chuck member; ,
Equipped with a,
The substrate is electrostatically chucked to an electrostatic chuck member in the transfer device as a mask used for extreme ultraviolet exposure when used for exposure with extreme ultraviolet light in a transfer device,
The position is characterized in that the placement portion places the vacuum chuck member in which the suction surface area and shape of the vacuum chuck member are formed in accordance with the suction surface area and shape of the electrostatic chuck member. Measuring device. Wherein the material of the vacuum chuck member, the position measuring device according to claim 1, which comprises using a material harder than the material used for the electrostatic chuck member.   The position measuring device according to claim 1, further comprising a control device that controls a suction force of the vacuum pump. The position measuring device further includes a gas supply unit that supplies gas via the vacuum chuck member,
2. The position measuring device controls the pressure of the suction surface of the vacuum chuck member to be higher than an external pressure by using the gas when the substrate is peeled from the vacuum chuck member. The position measuring device described.   The position measuring apparatus according to claim 1, wherein the vacuum chuck member includes a sensor that detects a position of the substrate.   The vacuum chuck member has a first suction mechanism for sucking a central portion of the back surface and a second suction mechanism for sucking a peripheral portion of the central portion when the back surface of the substrate is vacuum chucked. The position measuring device according to claim 1. In the arrangement portion, a plurality of vacuum chuck members are arranged,
The position measuring device according to claim 1, wherein each of the plurality of vacuum chuck members has an identification mark. When measuring the positional deviation amount in order to evaluate the positional accuracy assumed when the pattern transferred to the EUV mask is transferred onto the wafer, the back surface of the mask is planarized by selectively using a vacuum chuck. To correct and measure,
Wherein by selectively using three-point support method in measuring the positional deviation amount of the pattern drawn on the no correction of the mask backside shape for purposes of state management of the drawing device for drawing the EUV mask A positional deviation amount measuring method, characterized by measuring without correcting the shape of the back surface of the mask to a flat surface . Based on the three-dimensional shape of the back surface of the substrate when the influence of its own weight is eliminated, the positional deviation amount of the pattern predicted when the pattern is drawn on the surface of the substrate when the back surface of the substrate is corrected to a flat surface is corrected. Then, using the first pattern drawn, vacuum chuck the back surface of the substrate, measure the amount of displacement of the first pattern,
Using the second pattern drawn by correcting the positional deviation amount of the pattern predicted when a pattern is drawn on the front surface of the substrate without correcting the back surface of the substrate to a flat surface, three points on the back surface of the substrate are used. A misregistration amount measuring method, wherein the misregistration amount of the second pattern is measured in support.