JP2006005226A - Position measuring device and method, aligning device and method, exposure apparatus and method, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position measuring device, or the like capable of suppressing a frequency for changing a wide visual field sensor and a narrow one in the position measuring device for detecting a mark by changing the wide visual field sensor and the narrow one. <P>SOLUTION: A first measurement system 51 is used to observe a pattern RAM formed on a mask R, and correspondingly stores the position information of the pattern RAM with identification information for identifying the mask R. And a second measurement system 52 (52X, 52Y), which has a measurement visual field that is narrower than that of the first measurement system 51, is used to observe the pattern RAM by a measurement magnification that is higher than that of the first measurement system 51. And the pattern RAM on the prescribed mask R is measured by the first measurement system 51 after the position relationship between the measurement visual field of the second measurement system 52 and the pattern RAM is determined, on the basis of the position information corresponding to the information when the existence of the identification information regarding the prescribed mask R is recognized in the stored information. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus used in a photolithography process for manufacturing a device such as a semiconductor element, and more particularly to a position measurement method and apparatus for detecting position information of a mask and a substrate having alignment marks. is there.

Devices such as semiconductor elements, liquid crystal display elements, and thin film magnetic heads are manufactured by repeating each process such as a film formation process, an exposure process, and an etching process a plurality of times. An exposure apparatus that transfers the formed circuit pattern onto a photosensitive substrate is used. This exposure apparatus has a substrate stage on which a substrate is placed and moved two-dimensionally and a mask stage on which a mask having a circuit pattern is placed and moved two-dimensionally, and the circuit pattern formed on the mask is transferred to the mask stage. In addition, the substrate stage is transferred to the substrate through the projection optical system while sequentially moving the substrate stage.
In device manufacturing, the above steps are repeated. However, in the exposure apparatus, it is necessary to accurately overlay the next circuit pattern on the circuit pattern already formed on the substrate, so the mask and the substrate are positioned with high accuracy. Exposure processing is performed after alignment. The requirement for this alignment accuracy has become stricter with the miniaturization of circuit patterns, and various devices have been devised for alignment.

The mask alignment method generally uses exposure light. As an alignment method of the mask, VRA (detection mark position is detected by irradiating exposure light to the alignment mark formed on the mask and processing the image data of the alignment mark imaged by a CCD camera or the like. Visual Reticule Alignment) method.
On the other hand, as a substrate alignment method, an LSA (Laser Step Alignment) method in which a laser beam is irradiated onto a dot row alignment mark on the substrate and the mark position is detected using light diffracted or scattered by the alignment mark. FIA (Field Image Alignment) method that detects the mark position by illuminating the alignment mark with light having a wide wavelength bandwidth using a halogen lamp or the like, and processing the image data of the alignment mark imaged by a CCD camera or the like Alternatively, an LIA (Laser that detects the position of the alignment mark from its phase by irradiating the diffraction mark-shaped alignment mark on the substrate with laser light having a slightly different frequency from two directions, causing the two diffracted lights to interfere with each other. Interferometric alignment) method.
In these optical alignment methods, the alignment system detects an alignment mark on a mask using an alignment microscope, detects a position coordinate, detects an alignment mark on a substrate, and detects a position coordinate. Then, the position of the shot (projection area) to be superimposed is obtained. Based on these results, the substrate is moved by the substrate stage so that the circuit pattern image of the mask is superimposed on the shot area, and then the circuit pattern of the mask is projected and exposed onto the substrate.
JP 7-321030 A

By the way, in the VRA type reticle alignment method, the alignment mark provided on the mask is irradiated with the alignment light, and the reflected light is received by the sensor to detect the alignment mark. However, it is necessary to detect the alignment mark with high accuracy. Therefore, the field of view of the sensor is very narrow, and therefore it is not easy to put an alignment mark in the field of view of the sensor. Therefore, first, the rough position of the alignment mark is detected using the wide-field sensor, and the mask stage is moved based on the detection result so that the alignment mark falls within the field of view of the high-precision narrow-field sensor. The alignment mark is detected by the narrow field sensor.
However, in such a technique, it is necessary to switch between a wide-field sensor and a narrow-field sensor each time a mask is exchanged, and to detect an alignment mark by switching an optical member such as an ND filter accompanying the switching. There is. For this reason, when a mask is frequently changed, for example, when performing double exposure, when the number of wafers per lot is small, or when the exposure time per lot is short, a wide field of view is required. There is a problem that the ratio of the switching time between the sensor and the narrow-field sensor to the exposure processing time becomes high and throughput is lowered.

  The present invention has been made in view of the above-described circumstances, and suppresses the switching frequency of a wide-field sensor and a narrow-field sensor that detect a mark in a position measurement device that detects a mark using a wide-field sensor and a narrow-field sensor. An object of the present invention is to provide a position measurement device and the like that can perform the above-described operation.

In the position measurement apparatus, alignment apparatus, exposure apparatus, position measurement method, alignment method, exposure method, and device manufacturing method according to the present invention, the following means are employed in order to solve the above problems.
The first invention includes a first measurement system (51) for observing a pattern (RAM) formed on a mask (R), a measurement visual field narrower than the first measurement system, and the pattern (RAM) is a first one. The positional relationship between the measurement field of view of the second measurement system and the pattern (RAM) based on the measurement results of the second measurement system (52) and the first measurement system (51) observed at a measurement magnification higher than that of the measurement system. In the position measurement device (50) having a determination means (C1) for determining the position information of the pattern (RAM) measured by the first measurement system (51), the mask (R) Storage means (C2) associated with identification information for identifying) and storage means (C2) before the pattern (RAM) on the predetermined mask (R) is measured by the first measurement system (51). ) For identifying the predetermined mask (R) Determining means (C1) for determining presence / absence, and when the determining means (C1) determines that the storage means (C2) has identification information relating to the predetermined mask (R), the determining means (C1) C1) determines the positional relationship between the second measurement visual field and the pattern (RAM) based on positional information corresponding to the predetermined mask (R) stored in the storage means (C2). According to the present invention, when the pattern formed on the mask is fine-measured by the second measurement system, the second measurement is performed based on the position information of the pattern on the mask that has been rough-measured previously by the first measurement system. Since the positional relationship between the visual field and the pattern of the predetermined mask is determined, there is no need to switch between the first measurement system and the second measurement system each time measurement is performed, and the processing time can be shortened. In addition, since it is determined whether or not identification information (for example, drawing apparatus information) relating to the predetermined mask is provided, the predetermined mask may be the same as or different from the mask previously measured by the first measurement system. . That is, if the drawing apparatus information is the same, the positional relationship between the measurement visual field of the second measurement system and the pattern of the predetermined mask is determined based on the position information of the pattern on the mask previously measured by the first measurement system. can do.

  In addition, the first measurement system (51) for observing the pattern (RAM) formed on the mask (R) and a measurement visual field narrower than that of the first measurement system are provided, and the pattern (RAM) is provided more than the first measurement system. Determination to determine the positional relationship between the measurement field of view of the second measurement system and the pattern (RAM) based on the measurement results of the second measurement system (52) and the first measurement system (51) observed at a high magnification. In the position measurement device (50) having the means (C1), when drawing the pattern (RAM) on the mask (R), the position information of the pattern (RAM) measured by the first measurement system (51) is drawn. The storage means (C2) for storing the drawing apparatus information used in association with the memory and the pattern (RAM) on the predetermined mask (R) before the first measuring system (51) measures the predetermined mask (R). Read the drawing device information about the memory And a discriminating means (C1) for comparing and discriminating the drawing apparatus information stored in (C2), and the storage means (C2) has the same drawing apparatus information as the drawing apparatus information relating to the predetermined mask (R). Is determined by the determination means (C1), the determination means (C1) measures the second measurement system based on the position information corresponding to the same drawing device information stored in the storage means (C2). The positional relationship between the visual field and the pattern (RAM) is determined. According to this invention, it is not necessary to switch between the first measurement system and the second measurement system each time a pattern is measured, and the processing time can be shortened. In particular, since the drawing apparatus information relating to the predetermined mask is determined, even if the predetermined mask is different from the mask previously measured by the first measurement system, based on the position information of the pattern stored in the storage unit, The positional relationship between the measurement visual field of the second measurement system and the pattern of the predetermined mask can be determined.

Further, based on the positional relationship determined by the determining means (C1), the predetermined mask (R) is driven to control the relative positional relationship between the predetermined mask (R) and the measurement visual field of the second measurement system (52). A position control means (C1) is further included. When the position control means (C1) performs position control of the predetermined mask (R) based on the position information stored in the storage means (C2), a pattern (RAM) Is not within the measurement field of view of the second measurement system, and the first measurement system (51) is used to measure the predetermined mask (R), the pattern position information stored in the storage unit Based on this, even if the pattern of the predetermined mask cannot be positioned within the measurement visual field of the second measurement system, the pattern measurement is performed by measuring the pattern on the predetermined mask using the first measurement system. You can continue.
Moreover, it has a means (7) which adjusts the intensity | strength of the illumination light (L1) used when measuring on the mask (R) using the 1st measurement system (51) or the 2nd measurement system (52). The adjusting means (7) optimizes the intensity of illumination light for the first measurement system (51) when the measurement operation by the second measurement system (52) is performed based on the stored position information. If the measurement is not performed, it is not necessary to switch between the first measurement system and the second measurement system every time the pattern is measured. Therefore, the intensity of the illumination light with respect to the first measurement system by means for adjusting the intensity of the illumination light. Optimization can be omitted, and the processing time can be further shortened.
Further, the first measurement system (51) and the second measurement system (52) for detecting light generated from the mask (R) share a part of the measurement path up to an intermediate optical path branch point, and the optical path branch An adjustment means (57) for adjusting the intensity of light generated from the mask (R) is provided in at least one measurement optical path of the first measurement system (51) and the second measurement system (52) after the point. Then, it is possible to optimize the change in the intensity of light generated from the mask due to switching between the first measurement system and the second measurement system.
Further, the position information of the pattern (RAM) measured by the first measurement system (51) and stored in the storage means (C2) is obtained if the pattern (RAM) drawing error on the mask (R) is included. A pattern can be detected by searching within the range by the second measurement system based on the drawn drawing error.

  The second invention has a mask position measuring unit (50) for measuring the position of the mask (R) on which the circuit pattern (PA) is formed, and the substrate onto which the mask (R) and the circuit pattern (PA) are transferred. In the alignment apparatus (RA) that performs alignment with (W), the position measurement apparatus (50) of the first invention is used as the mask position measurement section (50). According to this invention, the detection time of the pattern formed on the mask during the alignment process can be shortened.

  In the third invention, after aligning the mask (R) on which the circuit pattern (PA) is formed and the substrate (W), an image of the circuit pattern (PA) irradiated by the exposure beam (EL) is displayed on the substrate (W ) In the exposure apparatus (EX) to be transferred onto, the alignment apparatus (RA) of the second invention is used as an apparatus for aligning the mask (R) and the substrate (W). According to the present invention, the mask alignment processing time can be shortened during the exposure processing.

  4th invention observes the pattern (RAM) formed on the mask (R) using the 1st measurement system (51), and the pattern (1) measured by the 1st measurement system (51) ( A second step of storing the position information of the RAM) in association with the identification information for identifying the mask (R) provided with the pattern (RAM), and a second step having a measurement field of view narrower than that of the first measurement system. Using the measurement system (52), a third step of observing the pattern (RAM) at a measurement magnification higher than that of the first measurement system, and the pattern (RAM) on the predetermined mask (R) as the first measurement system (51) ), The presence of the identification information about the predetermined mask is recognized by the fourth step for determining whether or not the identification information about the predetermined mask (R) is present in the information stored in the second step. Position information corresponding to the stored identification information. Based on, and to have a fifth step of determining the positional relationship between the measurement field and the pattern of the second measurement system (RAM). According to this invention, since the positional relationship between the measurement visual field of the second measurement system and the pattern of the predetermined mask is determined based on the position information of the pattern on the mask previously measured by the first measurement system, It is not necessary to switch between the first measurement system and the second measurement system every time, and the processing time can be shortened. In addition, since it is determined whether or not identification information (for example, drawing apparatus information) relating to the predetermined mask is provided, the predetermined mask may be the same as or different from the mask previously measured by the first measurement system. . That is, if the drawing apparatus information is the same, the positional relationship between the measurement visual field of the second measurement system and the pattern of the predetermined mask is determined based on the position information of the pattern on the mask previously measured by the first measurement system. can do.

  In addition, the first step of observing the pattern (RAM) formed on the mask (R) using the first measurement system (51), and the position of the pattern (RAM) measured by the first measurement system (51) A second step of storing information in association with the drawing apparatus information used when drawing the pattern (RAM) on the mask (R), and a second measurement having a narrower measurement field of view than the first measurement system A third step of observing the pattern (RAM) at a measurement magnification higher than the measurement magnification of the first measurement system using the system (52), and the pattern (RAM) on the predetermined mask (R) in the first measurement system Before measuring in (51), the drawing apparatus information relating to the predetermined mask (R) is read, and compared with the drawing apparatus information stored in the second step, and the predetermined mask (R) is determined in the fourth step. The same drawing device information as the drawing device information And the fifth step of determining the positional relationship between the measurement visual field of the second measurement system and the pattern (RAM) based on the positional information corresponding to the stored drawing device information. I made it. According to this invention, it is not necessary to switch between the first measurement system and the second measurement system each time a pattern is measured, and the processing time can be shortened. In particular, since the drawing apparatus information relating to the predetermined mask is determined, even if the predetermined mask is different from the mask previously measured by the first measurement system, based on the position information of the pattern stored in the storage unit, The positional relationship between the measurement visual field of the second measurement system and the pattern of the predetermined mask can be determined.

In addition, the first step of observing the pattern (RAM) formed on the mask (R) using the first measurement system (51), and the position of the pattern (RAM) measured by the first measurement system (51) A second step of storing information in association with the drawing apparatus information used when drawing the pattern (RAM) on the mask (R), and a measurement field of view narrower than the measurement field of view of the first measurement system A third step of observing the pattern (RAM) at a measurement magnification higher than that of the first measurement system using the second measurement system (52), and the information stored in the second step is When there is information on the mask (R) to be measured in step 3, the third step is performed using the stored information without going through the first step. According to the present invention, it is determined whether or not there is information relating to a mask to be measured thereafter, and if it exists, it is not necessary to go through the first measurement system every time the pattern is measured, and the processing time is shortened. be able to.
In the second step, the position information of the pattern (RAM) measured by the first measurement system is stored in association with the drawing apparatus information used when drawing the pattern (RAM) on the mask (R). Since the drawing device information used when drawing the pattern on the mask is stored, the mask to be measured later is different from the mask of the previous measurement target. If the drawing apparatus information is the same, the positional relationship between the measurement visual field of the second measurement system and the pattern of the predetermined mask can be determined based on the position information of the pattern stored in the storage unit.

  The fifth invention measures the position of the mask (R) on which the circuit pattern (PA) is formed and aligns the mask (R) and the substrate (W) onto which the circuit pattern (PA) is transferred. In the alignment method, the position measuring method of the fourth invention is used as a method for measuring the position of the mask (R). According to the present invention, it is possible to shorten the detection time of the pattern formed on the mask during the alignment process.

  In the sixth invention, after aligning the mask (R) on which the circuit pattern (PA) is formed and the substrate (W), the mask (R) is irradiated with the exposure beam (EL), and the circuit pattern (PA) In the exposure method for transferring the above image onto the substrate (W), the alignment method of the fifth invention is used as the alignment method between the mask (R) and the substrate (W). According to the present invention, the mask alignment processing time can be shortened during the exposure processing.

  In a seventh aspect of the present invention, in the device manufacturing method including the lithography step, the exposure method of the sixth aspect is used in the lithography step. According to the present invention, the throughput of the exposure apparatus can be improved.

According to the present invention, the following effects can be obtained.
A first invention includes a first measurement system for observing a pattern formed on a mask and a measurement field of view narrower than that of the first measurement system, and the pattern is observed at a measurement magnification higher than that of the first measurement system. In a position measurement apparatus having two measurement systems and a determination unit that determines the positional relationship between the measurement visual field and the pattern of the second measurement system based on the measurement result of the first measurement system, the position measurement device is measured by the first measurement system. Storage means for associating and storing the positional information of the pattern together with identification information for identifying the mask provided with the pattern, and the predetermined mask in the storage means before measuring the pattern on the predetermined mask by the first measurement system. And determining means for determining the presence or absence of identification information relating to, and when the determining means determines that the storage means has identification information relating to the predetermined mask, the determining means is stored in the storage means Based on position information corresponding to a predetermined mask, and to determine the positional relationship between the measurement field and the pattern of the second measurement system. As a result, it is not necessary to switch between the first measurement system and the second measurement system each time measurement is performed, and the processing time can be shortened. In particular, since the identification information relating to the predetermined mask is determined, even if the predetermined mask is different from the mask previously measured by the first measurement system, if the part of the identification information is the same, the storage unit Based on the stored pattern position information, the positional relationship between the measurement field of view of the second measurement system and the pattern of the predetermined mask can be determined.

  In addition, a first measurement system for observing the pattern formed on the mask and a measurement field of view narrower than the measurement field of view of the first measurement system are provided, and a second is used to observe the pattern at a measurement magnification higher than that of the first measurement system In a position measurement apparatus having a measurement system and a determination unit that determines a positional relationship between a measurement visual field and a pattern of the second measurement system based on a measurement result of the first measurement system, the position measurement device is measured by the first measurement system. Storage means for storing pattern position information in association with drawing apparatus information used when drawing the pattern on the mask, and a predetermined mask before measuring the pattern on the predetermined mask with the first measurement system A determination unit that reads the drawing device information and compares the drawing device information with the drawing device information stored in the storage unit; and the storage unit includes the same drawing device information as the drawing device information related to the predetermined mask. When determined by another means, the determination means determines the positional relationship between the measurement visual field and the pattern of the second measurement system based on the position information corresponding to the same drawing device information stored in the storage means. I did it. As a result, it is not necessary to switch between the first measurement system and the second measurement system each time a pattern is measured, and the processing time can be shortened. In particular, since the drawing apparatus information relating to the predetermined mask is determined, even if the predetermined mask is different from the mask previously measured by the first measurement system, based on the position information of the pattern stored in the storage unit, The positional relationship between the measurement visual field of the second measurement system and the pattern of the predetermined mask can be determined.

  According to a second aspect of the present invention, there is provided an alignment apparatus that includes a mask position measurement unit that measures a position of a mask on which a circuit pattern is formed, and performs alignment between the mask and a substrate onto which the circuit pattern is transferred. As described above, the position measuring device of the first invention is used. According to the present invention, the mask alignment process can be performed in a short time.

  According to a third aspect of the present invention, there is provided an exposure apparatus for aligning a mask on which a circuit pattern is formed and a substrate, and then transferring an image of the circuit pattern irradiated by the exposure beam onto the substrate. The alignment apparatus of the second invention is used. According to the present invention, the throughput of the exposure process for transferring the circuit pattern of the mask onto the substrate can be improved.

  4th invention identifies the mask provided with the pattern from the 1st process of observing the pattern formed on the mask using the 1st measurement system, and the positional information on the pattern measured by the 1st measurement system A pattern is observed at a measurement magnification higher than that of the first measurement system, using a second step of storing the identification information together with the second measurement system and a second measurement system having a narrower measurement field of view than the first measurement system. A third step, a fourth step for determining whether or not there is identification information relating to the predetermined mask in the information stored in the second step before measuring the pattern on the predetermined mask by the first measurement system; When the presence of the identification information related to the predetermined mask is recognized by the step 5, a fifth step of determining the positional relationship between the measurement visual field of the second measurement system and the pattern based on the positional information corresponding to the stored identification information To have. As a result, it is not necessary to switch between the first measurement system and the second measurement system each time a pattern is measured, and the processing time can be shortened.

  Also, the first step of observing the pattern formed on the mask using the first measurement system and the position information of the pattern measured by the first measurement system were used when drawing the pattern on the mask. A second step of observing a pattern at a measurement magnification higher than that of the first measurement system by using the second step of storing in association with the drawing apparatus information and the second measurement system having a measurement field of view narrower than that of the first measurement system. Three steps, a fourth step of reading the drawing apparatus information relating to the predetermined mask before measuring the pattern on the predetermined mask with the first measurement system, and comparing and discriminating with the drawing apparatus information stored in the second step; When the presence of the same drawing apparatus information as the drawing apparatus information related to the predetermined mask is recognized in the four steps, the measurement visual field of the second measurement system and the pattern are determined based on the position information corresponding to the stored drawing apparatus information. Positional relationship And to have a fifth step of determining. As a result, it is not necessary to switch between the first measurement system and the second measurement system each time a pattern is measured, and the processing time can be shortened. In particular, since the drawing apparatus information relating to the predetermined mask is determined, even if the predetermined mask is different from the mask previously measured by the first measurement system, based on the position information of the pattern stored in the storage unit, The positional relationship between the measurement visual field of the second measurement system and the pattern of the predetermined mask can be determined.

  According to a fifth aspect of the present invention, there is provided an alignment method for measuring a position of a mask on which a circuit pattern is formed and aligning the mask and a substrate onto which the circuit pattern is transferred. The position measuring method of the invention is used. According to the present invention, the mask alignment process can be performed in a short time.

  According to a sixth aspect of the present invention, there is provided an exposure method of aligning a mask on which a circuit pattern is formed and a substrate, and then irradiating the mask with an exposure beam to transfer an image of the circuit pattern onto the substrate. As the method, the alignment method of the fifth invention is used. According to the present invention, the throughput of exposure processing can be improved.

  In a seventh aspect of the present invention, in the device manufacturing method including the lithography step, the exposure method of the sixth aspect is used in the lithography step. According to this invention, the manufacturing cost of a device can be suppressed.

Embodiments of a position measurement apparatus, alignment apparatus, exposure apparatus, position measurement method, alignment method, exposure method, and device manufacturing method according to the present invention will be described below with reference to the drawings.
FIG. 1 is a conceptual view showing an exposure apparatus EX of the present invention. The exposure apparatus EX is formed on the reticle R by relatively moving the reticle R and the wafer (substrate) W synchronously in a one-dimensional direction while illuminating the reticle (mask) R with exposure light (exposure beam) EL. This is a so-called scanning stepper, a step-and-scan type scanning exposure apparatus that transfers the circuit pattern PA onto the wafer W via the projection optical system PL.
As shown in FIG. 1, the exposure apparatus EX supports a light source 1 for exposure, an illumination optical system IL that illuminates the reticle R with exposure light EL based on a light beam emitted from the light source 1 with uniform illuminance, and the reticle R. Reticle stage RST, projection optical system PL that irradiates exposure light EL emitted from reticle R onto wafer W, wafer stage WST that supports wafer W, controller CONT, focus position detection system AF, and various alignment optical systems RA , WA1, WA2, etc.
Here, the X-axis direction is a predetermined direction in the horizontal plane, the Y-axis direction is a direction orthogonal to the X-axis direction in the horizontal plane, and the Z-axis direction is orthogonal to each of the X-axis direction and the Y-axis direction. It is assumed that the direction is The optical axis of the projection optical system PL is assumed to coincide with the Z-axis direction.

As the light source 1, vacuum ultraviolet rays having a wavelength of about 120 nm to about 190 nm, for example, ArF excimer laser (wavelength: 193 nm), fluorine (F ₂ ) laser (157 nm), krypton (Kr ₂ ) laser (146 nm), argon (Ar ₂ ) ) A light source that generates a laser (126 nm) or the like is used. Further, the light source 1 is provided with a light source control device (not shown), and this light source control device controls the oscillation center wavelength and spectral half width of the emitted exposure light EL in accordance with an instruction from the control device CONT. Trigger control of pulse oscillation.
In the present embodiment, ArF excimer laser light is used as the exposure light EL.

The illumination optical system IL adjusts the light beam emitted from the light source 1 to a light beam having a substantially uniform illuminance distribution and converts it into exposure light EL, and adjusts the area of the aperture through which the exposure light EL passes to adjust the reticle R. And a condenser lens system 4 for condensing the exposure light EL and illuminating the reticle R with uniform illuminance. The blind BL is disposed at a position conjugate with the circuit pattern PA of the reticle R.
Accordingly, the illumination optical system IL irradiates the exposure light EL with a substantially uniform illuminance distribution onto the circuit pattern area PA of the reticle R supported by the reticle stage RST.

The reticle stage RST has a reticle holder RH that holds the reticle R by vacuum suction or a method using an electrostatic chuck or an electromagnet. The reticle holder RH and the reticle stage RST have openings corresponding to the circuit pattern area PA of the reticle R. The reticle stage driving unit RSTD including a voice coil motor or the like causes the X axis direction, the Y axis direction, and the θZ direction ( Fine movement is possible in the rotation direction around the Z axis).
On reticle stage RST, moving mirror 10X extending in the Y-axis direction and moving mirror 10Y (see FIG. 2) extending in the X-axis direction are provided. The moving mirror 10X is irradiated with a measurement beam from the laser interferometer 21X via the mirror 22. Reflected light from the moving mirror 10X is received by a detector in the laser interferometer 21X, and the position of the reticle R in the X-axis direction is detected based on the light reception result. Similarly, the length measurement beam is irradiated from the laser interferometer 21Y (not shown) to the movable mirror 10Y, and the reflected light from the movable mirror 10Y is received by the detector in the laser interferometer 21Y, and the reticle R is based on the light reception result. Is detected in the Y-axis direction. The detection results of these laser interferometers 21 (21X, 21Y) are output to the control device CONT.

The projection optical system PL is a system in which a plurality of projection lens systems such as a lens made of fluoride crystals such as fluorite and lithium fluoride and a reflecting mirror are sealed with a projection system housing, and is provided immediately below the reticle stage RST. The projection lens system reduces the exposure light EL emitted through the reticle R by a predetermined projection magnification β (β is, for example, 1/4), and converts the image of the circuit pattern PA on the reticle R into a specific area on the wafer W. An image is formed on the (shot area). Each element of the projection lens system of the projection optical system PL is supported by the projection system housing via a holding member (not shown), and each holding member is, for example, in an annular shape so as to hold the peripheral edge of each element. Is formed.
In addition, since vacuum ultraviolet rays are used as the exposure light EL, fluorite (CaF ₂ crystal), quartz glass doped with fluorine, hydrogen, etc., and magnesium fluoride (Optical element) having good transmittance are used. MgF ₂ ) or the like is used. In this case, in the projection optical system PL, it is difficult to obtain a desired imaging characteristic (chromatic aberration characteristic, etc.) by using only a refractive optical member. Therefore, the catadioptric system in which the refractive optical member and the reflecting mirror are combined. May be adopted.

Wafer stage WST is provided on XY stage XYS, which can be moved in a two-dimensional plane (XY plane) by wafer stage drive unit WSTD equipped with a linear motor, and in the Z-axis direction by wafer stage drive unit WSTD. And a Zθ stage ZS that can be rotated slightly around the Z axis, and a wafer holder WH that is provided on the Zθ stage ZS and holds the wafer W by vacuum suction or electrostatic chuck. The XY stage XYS has a structure in which a pair of blocks movable in directions orthogonal to each other are overlapped, and can move in the X-axis direction and the Y-axis direction on the apparatus base based on the driving of the wafer stage drive unit WSTD. Yes. Further, wafer stage WST is provided so as to be movable in the tilt direction with respect to the optical axis of projection optical system PL, and when wafer W is supported, position adjustment including leveling adjustment of wafer W is possible.
On wafer stage WST, movable mirror 11X extending in the Y-axis direction and movable mirror 11Y (see FIG. 3) extending in the X-axis direction are provided. The moving mirror 11X is irradiated with a measurement beam from the laser interferometer 23X via the mirror 24. The reflected light from the movable mirror 11X is received by a detector in the laser interferometer 23X, and the position of the wafer W in the X-axis direction is detected based on the light reception result. Similarly, the movable mirror 11Y is irradiated with a length measurement beam from a laser interferometer 23Y (not shown), and the reflected light from the movable mirror 11Y is received by a detector in the laser interferometer 23Y. Is detected in the Y-axis direction. The detection results of these laser interferometers 23 (23X, 23Y) are output to the control device CONT.

  The control device CONT controls the exposure apparatus EX in an integrated manner. In addition to a calculation unit (determination unit, determination unit, control unit) C1 that performs various calculations and controls, a storage unit (storage unit) that records various types of information. ) C2, the input / output unit C3, and the like. Then, for example, the exposure of transferring the image of the circuit pattern PA formed on the reticle R to the shot area on the wafer W by controlling the positions of the reticle R and the wafer W based on the detection results of the laser interferometers 21 and 23. Repeat the operation.

The gas supply device 5 blocks the space through which the exposure light EL passes, that is, the illumination optical path (the optical path from the light source 1 to the reticle R) and the projection optical path (the optical path from the reticle R to the wafer W) from the external atmosphere. This is an apparatus that fills the optical path with a low-absorbing gas (for example, an inert gas such as nitrogen, helium, argon, neon, krypton, or a mixed gas thereof) having a characteristic that absorbs less light in the vacuum ultraviolet region.
The gas supply device 5 is provided because the exposure light EL used in the exposure apparatus EX, that is, light having a wavelength of about 190 nm or less called vacuum ultraviolet rays, gas such as oxygen molecule, water molecule, carbon dioxide molecule, organic matter, etc. This is because it has a property of being easily absorbed by a light-absorbing substance, and cannot penetrate into the atmosphere. For this reason, when vacuum ultraviolet rays are used for the exposure light EL, the light-absorbing substance existing in the space through which the exposure light EL passes is reduced so that the exposure light EL reaches the upper surface of the wafer W with sufficient illuminance.
Specifically, as shown in FIG. 1, nitrogen (N ₂ ) gas is supplied to the illumination optical system IL, a reticle alignment system RA, which will be described later, and the projection optical system PL via supply pipes 5A, 5B, and 5C. By purging these spaces with nitrogen gas, the above-described problem of absorption of the exposure light EL due to oxygen or the like is solved.
The gas supply device 5 may be a circulation system in which the supplied gas is recovered through the pipes 6A, 6B, and 6C and purified and supplied again, or the supplied gas is supplied to the pipes 6A and 6B. , 6C may be used as a non-circulation type.
Further, although not shown, the reticle stage RST and wafer stage WST are provided with a local purge device for supplying nitrogen gas onto the optical path through which the exposure light EL passes or a housing that covers the reticle stage RST and wafer stage WST. Nitrogen gas is supplied to the substrate to solve the problem of absorption of the exposure light EL.

Further, the exposure apparatus EX is provided with a focus position detection system (autofocus sensor) AF for detecting the position (focal position) in the Z-axis direction of the surface of the wafer W. The focal position detection system AF includes a light transmitting unit and a light receiving unit on the side surface of the projection optical system PL. FIG. 1 shows only the light transmission unit, and does not show the light receiving unit disposed on the opposite side of the light transmission unit across the projection optical system PL.
Non-photosensitive detection light is applied to the wafer W from the light transmission unit. A large number of slits are provided between the light transmitting unit and the wafer W, and the detection light illuminates the large number of slits, and the images of these slits are obliquely on the wafer W with respect to the optical axis of the projection optical system PL. Projected on. The light receiving unit detects the detection light reflected on the wafer W. When detecting the best imaging plane (best focus plane), the wafer stage WST is driven to change the position of the wafer W in the Z-axis direction from the light transmitting portion of the focal position detection system AF to the wafer W. The detection light is irradiated, and the light receiving unit detects the light generated from the wafer W by the irradiation of the detection light, and the best imaging plane is detected based on the detection result. Since the focus position detection system AF is a multipoint AF sensor, the tilt of the wafer W can also be detected.

Further, the exposure apparatus EX is provided with various alignment optical systems. Specifically, the reticle alignment system includes a reticle alignment system RA of a TTR (Through The Reticule) method and a video reticle alignment (VRA) method. Further, as an off-axis type wafer alignment system, an FIA (Field Image Alignment) type wafer alignment system WA1 is provided. Further, as a TTL (Through The Lens) type wafer alignment system, an LSA (Laser Step Alignment) type or LIA (Laser Interferometric Alignment) type wafer alignment system WA2 is provided.
These various alignment optical systems RA, WA1 and WA2 perform alignment processing using various marks provided on reticle stage RST, wafer stage WST, reticle R or wafer W.

Prior to description of the various alignment optical systems RA, WA1, and WA2, various marks and the like will be described with reference to FIGS. 2 is a schematic view of the reticle stage RST on which the reticle R is placed as viewed from the incident direction side of the exposure light EL, and FIG. 3 is a schematic view of the wafer stage WST on which the wafer W is placed as viewed from the projection optical system PL side. FIG. 4A shows an alignment mark RAM formed on the reticle R, and FIG. 4B shows a VRA mark FMV formed on the wafer stage WST.
First, as shown in FIG. 2, the reticle R is provided with various marks. On the lower surface side of the reticle R, an alignment mark (pattern) RAM and a search mark RSM are formed on the outer peripheral portion of the region where the circuit pattern PA for transfer is formed by chromium vapor deposition (hereinafter referred to as these). The mark RAM and RSM are collectively referred to as a reticle mark group RM).
The alignment mark RAM and the search mark RSM are each provided with a pair of two marks at positions separated from the center of the reticle R by a predetermined design value in the X direction across the circuit pattern area PA. A pair of search marks RSM are provided at approximately the center of the reticle R. The alignment mark RAM is provided in a total of six pairs, three pairs each symmetrically in the Y direction across the search mark RSM. The distance between the search mark RSM and the alignment mark RAM is measured in advance for each reticle R and stored in the control device CONT.
The search mark RSM is a cross-shaped mark as shown in FIG. Further, as shown in FIG. 4A, the alignment mark RAM is a mark with a quadrangular mark superimposed on a cross-shaped mark.

On wafer stage WST, as shown in FIG. 3, a reference mark member WFP made of a transparent material having a low expansion coefficient, such as quartz, fixed to Zθ stage ZS is provided, and on the surface of reference mark member WFP, Various reference mark groups (Fiduciary mark) FM are formed by chromium vapor deposition or the like. The reference mark group FM is provided to have the same height as the wafer W.
The reference mark group FM includes a VRA mark FMV used in the VRA type reticle alignment system RA. Further, the reference mark group FM is formed for each of the above-mentioned LSA system, LIA system, or FIA system alignment systems to check the baseline amount (the LSA mark, the LIA mark, and the FIA mark: all (Not shown). These marks are formed at predetermined positions determined in advance with reference to the VRA mark FMV.
As shown in FIG. 4B, the VRA mark FMV is a mark having a shape in which three line-shaped marks are evenly arranged in four directions. The two VRA marks FMV are paired and arranged on the reference mark member WFP by a predetermined distance in the X direction. The interval between the pair of VRA marks FMV is set to be the same as the interval between the reduced images of the pair of search marks RSM formed on the reticle R by the projection optical system PL.

Returning to FIG. 1, the off-axis wafer alignment system WA1 is provided on the side of the projection optical system PL, and the alignment light source 34 emits alignment light having a wavelength different from that of the exposure light EL, and the alignment light source. A beam splitter 35 to which alignment light from 34 is incident, an optical system 37 that guides alignment light emitted from the alignment light source 34 to the reference mark group FM (or wafer W), and irradiation of the alignment light. Among them, a light receiving unit 36 that receives light generated from the FIA mark (or the alignment mark provided on the wafer W) is provided.
The wafer alignment system WA1 is an FIA system, a halogen lamp is used as the alignment light source 34, and an image sensor such as a CCD is used as the light receiving unit 36. Then, the light receiving unit 36 outputs the imaging result to the control device CONT, and the control device CONT performs image processing based on the imaging result of the light receiving unit 36. The wafer alignment system WA1 irradiates the cross-shaped FIA mark (or the alignment mark of the wafer W) of the reference mark group FM with light having a wide wavelength bandwidth emitted from the alignment light source 34 composed of a halogen lamp, and controls the control device CONT. The mark position is detected by performing image processing under.
Based on the detection result, the reference point of the observation region of the off-axis wafer alignment system WA1 is obtained.

As shown in FIG. 1, the LSA wafer alignment system WA2 includes an alignment light source 33 made of a He—Ne laser, a beam splitter 32 to which alignment light emitted from the alignment light source 33 is incident, and a cylindrical (not shown). A lens and a field stop, an optical system 38 that causes alignment light emitted from the alignment light source 33 to enter the projection optical system PL, and an LSA mark (or alignment provided on the wafer W) in the reference mark group FM by irradiation of the alignment light. And a light receiving unit 31 that receives light generated from the mark). The alignment light emitted from the alignment light source 33 is shaped into an elongated slit-like spot light, and then irradiates the LSA mark in the reference mark group FM via the projection optical system PL.
The LSA marks are lattice marks arranged at predetermined intervals in the longitudinal direction of the spot light. When the wafer stage WST is driven to scan the LSA mark with respect to the spot light, diffracted light is generated in a predetermined direction when the LSA mark matches the spot light. The diffracted light returns to the wafer alignment system WA2 via the projection optical system PL and is received by the light receiving unit 31. The light reception signal of the light receiving unit 31 is output to the control device CONT, and the control device CONT detects the position of the LSA mark by sampling the coordinates of the wafer stage WST when the alignment signal becomes maximum, for example. Based on the detection result, the reference point of the observation area of the LSA type wafer alignment system WA2 is obtained.
The LSA alignment system is disclosed in detail in, for example, Japanese Patent Application Laid-Open No. 60-130742.

When the wafer alignment system WA2 is LIA, the alignment light emitted from the alignment light source 33 made of a He—Ne laser is transmitted through the beam splitter 32 and a two-beam frequency shifter (not shown) to the optical system 38. Is incident on the projection optical system PL. The alignment light (laser light beam) having the frequencies f1 and f2 that have become two light beams is irradiated so as to overlap the LIA mark having a diffraction grating shape in the reference mark group FM. In the LIA mark, two diffracted lights are generated in the same direction by the two irradiated light beams.
The interference signal of the interference light composed of these two diffracted lights is detected by the light receiving unit 31, and the control device CONT detects the position of the LIA mark based on the detection result of the light receiving unit 31. Based on the detection result, the reference point of the observation area of the LIA type wafer alignment system WA2 is obtained.
The LIA type alignment system is disclosed in detail in, for example, Japanese Patent Laid-Open No. 61-215905.

FIG. 5 is a conceptual diagram showing a VRA type reticle alignment system RA, and shows a case where the reticle alignment system RA irradiates the reticle R.
As shown in FIG. 5, reticle alignment system RA is provided between illumination optical system IL and reticle stage RST, and uses exposure light EL as alignment light (illumination light) L1. Specifically, ArF excimer laser light is guided from the light source 1 through the ND filter (adjusting means) 7 and the optical fiber 41.
The VRA type reticle alignment system RA includes an irradiation system 42 that irradiates the reticle R having the reticle mark group RM with the alignment light L1 based on the exposure light EL emitted from the illumination optical system IL. The irradiation system 42 has a plurality of optical elements, and converts the incident exposure light EL into alignment light L1 by passing it through, and irradiates the reticle R with the alignment light L1. The irradiation system 42 includes a blind 43 for shaping the irradiation range, and a rectangular irradiation range is shaped based on the opening of the blind 43.
Then, the alignment light L1 from the irradiation system 42 irradiates the reticle mark group RM formed on the reticle R via the mirror 44 and the like, and at the same time, the reference mark member WFP on the wafer stage WST via the projection optical system PL. The reference mark group FM provided on the lens is also irradiated.

Furthermore, the reticle alignment system RA includes a detection device 50 that detects position information of the reticle mark group RM based on light information (reflected light) generated from the reticle R by irradiation of the alignment light L1.
The detection device (position measurement device, mask position measurement unit) 50 is a low-magnification rough measurement alignment microscope (first measurement system) capable of measuring a wide area on the reticle R with a predetermined accuracy via the low-magnification optical system 54. 51 and a high-magnification fine measurement alignment microscope (second measurement system) 52 capable of measuring a region narrower than a region measurable with the low-magnification alignment microscope 51 through the high-magnification optical system 55 with high accuracy. ing. Each of the low-magnification alignment microscope 51 and the high-magnification alignment microscope 52 includes an image sensor (CCD) and is optically coaxially arranged. Light (reflected light) generated by irradiating the reticle R with the alignment light L1 is guided to the half mirror 53 via the objective optical system 45 and the mirror 44, and then passed through the low magnification optical system 54 and the high magnification optical system 55, respectively. Via the image sensor of the low-magnification alignment microscope 51 and the high-magnification alignment microscope 52 (52X, 52Y). The number of optical elements (optical members such as lenses) used in the high magnification optical system 55 is larger than that in the low magnification optical system 54. The light (reflected light) received by the high-magnification alignment microscope 52 is guided from the high-magnification optical system 55 to the neutral density filter 57 and the half mirror 56, and is split into the X-direction component and the Y-direction component, respectively. The light enters the high-magnification alignment microscopes 52X and 52Y.
The reason why the neutral density filter (adjusting means) 57 is provided is to adjust the reflected light to the optimum light quantity of the high-magnification alignment microscope 52. Similarly, a filter for adjusting the light intensity on the low-magnification alignment microscope 51 side, etc. May be provided. In addition, the present invention is not limited to the case where the neutral density filter 57 or the like is provided, and gain adjustment may be performed in the electrical system of the detection device 50 to adjust the optimal light amount.
Each of the low-magnification alignment microscope 51 and the high-magnification alignment microscope 52 also receives light (reflected light) generated from the reference mark member WFP of the wafer stage WST via the projection optical system PL.

The low-magnification alignment microscope 51 irradiates a wide area on the reticle R with the alignment light L1, and detects light information generated from the search mark RSM on the reticle R by the irradiation with the alignment light L1. Further, the high magnification alignment microscope 52 irradiates a narrow region on the reticle R with the alignment light L1, and detects optical information generated from the alignment mark RAM of the reticle R by the irradiation of the alignment light L1.
Information detected by the low-magnification alignment microscope 51 and the high-magnification alignment microscope 52 is output to the control device CONT, and position information of the search mark RSM and the alignment mark RAM is detected based on the information.
The various optical systems provided in the reticle alignment system RA are made of quartz or fluorite because ArF excimer laser light is used as detection light for alignment (all lenses are made of quartz or all of them are made of quartz). These lenses are preferably made of fluorite, or a mixed type structure where some lenses are quartz and other lenses are fluorite.
Further, as described above, the reticle alignment system RA is supplied (purged) with nitrogen gas from the gas supply device 5 via the supply pipe 5B.

Next, a method for measuring position information of the alignment mark RAM using the exposure apparatus EX having the above configuration will be described. FIG. 6 is a diagram for explaining a method of measuring the position of the alignment mark RAM by the reticle alignment system RA.
As shown in FIG. 6, the position measuring method of the present invention includes a step S10 (S11 to S13) of detecting an alignment mark RAM and the like with a low-magnification alignment microscope 51, and a step of storing position information and the like of the alignment mark RAM. S20 and a step S30 (S31 to S33) for detecting the alignment mark RAM with the high-magnification alignment microscope 52, and a step S40 for determining the identification information of the reticle R when the reticle is exchanged. And step S50 for reading position information of the alignment mark RAM, and after these processes, an alignment and exposure step S60 (S61 to S63) is included.

First, in step S10 of detecting the alignment mark RAM with the low magnification alignment microscope 51, the reticle R is placed on the reticle stage RST by a reticle loader (not shown) (step S11). It is desirable that the reticle R positioning accuracy and repeatability by the reticle loader be as high as possible. This is because the higher the positioning accuracy, the better the detection rate of the alignment mark RAM in step S32 described later.
Next, the reticle alignment system RA irradiates the reference mark group FM of the reference mark member WFP with the alignment mark LRM provided on the reticle R and the reference mark group FM of the reference mark member WFP via the alignment light L1 made of ArF excimer laser light. . Then, the search mark RSM is observed by the low-magnification alignment microscope 51, and the position information is output to the control device CONT (step S12). When the search mark RSM is observed with the low-magnification alignment microscope 51, the ND filter ( adjusting means) 7 is switched for adjusting the illuminance of the alignment light L1. This is to optimize the amount of light detected by the low-magnification alignment microscope 51 such as the search mark RSM, and an optimal ND combination is obtained in advance and stored in the storage unit C2 of the control device CONT.
In step S13, the control device CONT to which the position information of the search mark RSM is sent is based on the distance relationship between the search mark RSM and the alignment mark RAM stored in advance in the storage unit C2. The position information of the mark RAM is obtained (detected).
As in steps S12 and S13 (first step), the detection mark RSM is detected to indirectly determine the position of the alignment mark RAM because the detection accuracy of the low magnification alignment microscope 51 is not sufficient. to cause. That is, the low magnification alignment microscope 51 has a wide measurement field of view so that the reticle mark group RM formed on the reticle R can be reliably observed. For this reason, the detection accuracy of the reticle mark group RM is relatively low. Therefore, if the alignment mark RAM is directly detected, sufficient detection cannot be ensured. Therefore, the search mark RSM that facilitates ensuring the detection accuracy of the low-magnification alignment microscope 51 is used.

Next, in step S20 (second step), that is, the step of storing the position information of the alignment mark RAM, the position information of the search mark RSM detected indirectly by the low magnification alignment microscope 51 is stored in the control device CONT. Store in part C2. At this time, identification information relating to the measured reticle R is also stored in association with the position information of the search mark RSM.
The identification information related to the reticle R includes, for example, a manufacturing number, circuit pattern information, reticle size information (thickness error, etc.), reticle mark group RM information (alignment mark RAM arrangement information, drawing error, etc.), drawing apparatus information, etc. This is individual information (profile) for each reticle R. Note that the drawing apparatus information is information relating to the drawing apparatus in which the circuit pattern of the reticle R and the reticle mark group RM are formed on the reticle R.
Specifically, identification information relating to the reticle R (individual information for each reticle R) is stored in advance in an external storage device (not shown). Further, when the reticle R is placed on the reticle holder RH, barcode information (manufacturing number and the like) printed on the reticle R is read by a barcode reader (not shown). Then, based on the read barcode information, the individual information of the reticle R is input from the external storage device to the control device CONT via the input / output unit C3, and stored in association with the measured position information of the search mark RSM. Instead of using a barcode reader, when observing the search mark RSM in step S12, the barcode information printed on the reticle R may be read simultaneously with the low-magnification alignment microscope 51.

Next, in step S30 (third step) in which the alignment mark RAM is detected by the high magnification alignment microscope 52, the calculation unit C1 of the control unit CONT is based on the position information of the alignment mark RAM obtained in step 13. The position (X ₀ , Y ₀ ) of the alignment mark RAM with respect to the measurement field of view of the high magnification alignment microscope 52 is determined (see FIG. 7B). Then, the reticle stage drive unit RSTD is instructed to control the reticle stage RST, and the alignment mark RAM is positioned at the obtained position (X ₀ , Y ₀ ) (step S31). As a result, the alignment mark RAM is introduced into the measurement field of view of the high magnification alignment microscope 52 of the reticle alignment system RA.
Wafer stage WST is positioned so that the centers of the pair of VRA marks FMV on reference mark member WFP substantially coincide with optical axis AX of projection optical system PL. Then, the interval between the pair of VRA marks FMV is set to be approximately equal to the interval between the reduced images obtained by the projection optical system PL of the pair of alignment marks RAM. An enlarged image of the mark FMV by the projection optical system PL appears so as to overlap the alignment mark RAM.
When the alignment mark RAM is introduced into the measurement field of view of the high magnification alignment microscope 52, the ND filter 7 is switched to adjust the illuminance of the alignment light L1. This is to optimize the amount of light detected by the alignment mark RAM or the like by the high-magnification alignment microscope 52, and an optimum ND combination is obtained in advance and stored in the storage unit C2 of the control device CONT.

Next, in step 32, the alignment mark RAM is observed and detected by the high-magnification alignment microscope 52.
7A and 7B are diagrams showing an alignment mark RAM and a VRA mark FMV that are observed by the high-magnification alignment microscope 52 of the reticle alignment system RA. FIG. 7A is an image example, and FIG. 7B is an image thereof. It is an example of a signal obtained from (X direction).
As shown in FIG. 7A, the high-magnification alignment microscope 52 simultaneously observes the pair of VRA marks FMV formed on the reference mark member WFP and the pair of alignment mark RAMs provided on the reticle R. The image information is output to the control device CONT. When observing the mark RAM and FMV with the high-magnification alignment microscope 52, the objective optical system 45 of the reticle alignment system RA is moved to perform focus adjustment (RAAF) of the high-magnification alignment microscope 52. Good.
Then, as shown in FIG. 7B, the control device CONT processes the received image information to detect the alignment mark RAM and the VRA mark FMV. That is, the control device CONT obtains the positions of the alignment mark RAM and the VRA mark FMV projected in the measurement field of view of the high-magnification alignment microscope 52 in the X direction and the Y direction.

Next, in step S33, it is determined whether or not the alignment mark RAM can be detected. That is, the alignment mark RAM is observed with the high-magnification alignment microscope 52 to determine whether or not the alignment mark RAM can be detected. As described above, whether or not the alignment mark RAM can be detected is determined when the alignment mark RAM cannot be reliably detected when the alignment mark RAM is detected via step S50 described later. Because there is. Therefore, if it is determined that the alignment mark RAM cannot be reliably detected, the process returns to step S12, and observation and detection using the low-magnification alignment microscope 51 are performed again.
Note that, when not passing through step S50, that is, when passing through steps S10 and S20, the alignment mark RAM is detected almost certainly, so the description will be continued for the case where it is determined that the alignment mark RAM has been detected.

When the alignment mark RAM is detected, alignment and exposure processes are performed in step S60.
First, in step S61, the control unit CONT obtains a deviation amount (ΔX ₁ −ΔX ₂ , ΔY ₁ −ΔY ₂ ) of the pair of alignment mark RAM and VRA mark FMV in the X direction and the Y direction.
Further, the control device CONT positions the reticle stage RST so that the positional deviation amounts of the pair of marks FMV and RAM are within a predetermined range and symmetrical to each other, and the VRA mark FMV on the reference mark member WFP. Is adjusted (controlled) so that the alignment mark RAM of the reticle R coincides (overlaps in a predetermined arrangement).
In this manner, the pair of alignment mark RAMs, and consequently the circuit pattern PA of the reticle R, is positioned (aligned) with respect to the pair of VRA marks FMV formed on the reference mark member WFP.
In other words, the center (exposure center) of the reduced image by the projection optical system PL of the circuit pattern PA of the reticle R is substantially positioned at the center (substantially the optical axis AX) of the VRA mark FMV, and the contour of the circuit pattern area PA. The orthogonal sides are set parallel to the X axis and the Y axis, respectively. In this state, the control device CONT stores the coordinates of the wafer stage WST in the X direction and the Y direction measured by the laser interferometer 23, thereby completing the alignment of the reticle R. Thereby, an arbitrary point on wafer stage WST can be moved to the exposure center of circuit pattern PA.
After the alignment process, an exposure process for transferring the circuit pattern PA of the reticle R to the shot area of the wafer W is performed.

  After the alignment process and the exposure process are completed, it is determined in step S62 whether or not the reticle R is exchanged and the exposure process is continued. If the exposure process is to be continued, reticle exchange is performed in step S63. On the other hand, when the exposure processing is completed, the series of processing ends (END).

When the reticle is exchanged, the identification information of the exchanged reticle R is determined in step S40 (fourth process). The discrimination of the identification information of the reticle R is the presence / absence of the identification information of the reticle after the exchange (hereinafter, reticle R ₁ ), that is, whether or not the identification information of the reticle R ₁ is stored in the storage unit C2 of the control device CONT. It is. In particular, it is whether or not drawing device information in the identification information is stored.
Specifically, the reticle R ₁ is the same as the reticle (hereinafter referred to as reticle R ₀ ) on which the alignment mark RAM has been detected by the low magnification alignment microscope 51 before, or the reticle R ₁ has previously been at low magnification. It is determined whether or not the same drawing apparatus information as the reticle R _{0 from} which the alignment mark RAM has been detected by the alignment microscope 51 is provided.
That is, if the reticle R ₁ is the same as the reticle R ₀ for which the alignment mark RAM was previously detected by the low magnification alignment microscope 51, the positional information of the alignment mark RAM exists in the storage unit C2. The process of step S30 can be performed based on the position information of the alignment mark RAM existing in the storage unit C2, without performing the above-described steps S12 to S13 and S20 again.
Even if the reticle R ₁ and the reticle R ₀ are different, the positions of the alignment mark RAMs formed on the reticle R ₀ and the reticle R ₁ as long as they are manufactured by the same drawing apparatus. Are likely to be substantially identical. Therefore, by replacing the position information of the alignment mark RAM of the reticle R ₀ existing in the storage unit C 2 with that of the reticle R ₁ , steps S 12 to S 13 and S 20 can be omitted and the process of step S 30 can be performed.
Then, if the identification information of the reticle R ₁ does not exist in the storage unit C2, or when the same drawing device information and drawing device information of the identification information of the reticle R ₁ does not exist in the storage unit C2 is step S12 It proceeds to a low magnification the alignment microscope 51 observation of the search mark RSM of the reticle R ₁ by is performed. On the other hand, when the identification information or the same drawing device information of the reticle R ₁ is present in the storage unit C2 is, processing proceeds to step S50.

Subsequently, in step S50 (fifth step), when the identification information of the reticle R ₁ is present in the storage unit C2 reads the positional information of the alignment marks RAM stored in association with the identification information. On the other hand, if the same drawing device information and drawing device information of the identification information of the reticle R ₁ is present in the storage unit C2, the position of the alignment marks RAM stored in association with the same drawing apparatus information Read information. That is, the position information of the alignment mark RAM is sent from the storage unit C2 to the calculation unit C1.
Thereby, as described above, steps S12 to S13 and S20 can be performed without performing again or omitted, and the process of step S30 can be performed based on the read position information of the alignment mark RAM.

Then, the process proceeds to step S30 again, and the calculation unit C1 of the control device CONT determines the position (X ₀₎ of the alignment mark RAM with respect to the measurement field of view of the high-magnification alignment microscope 52 based on the read position information of the alignment mark RAM. , Y ₀ ) is determined (see FIG. 7B). Then, the reticle stage drive unit RSTD is instructed to control the reticle stage RST, and the alignment mark RAM is positioned at the obtained position (X ₀ , Y ₀ ) (step S31). Thereby, if the position information of the read alignment mark RAM is appropriate, the alignment mark RAM is introduced into the measurement field of view of the high magnification alignment microscope 52.
Next, in step S32, the alignment mark RAM is observed and detected, and in step S33, whether or not the alignment mark RAM is detected is determined. As described above, since the reticle replacement work is performed through step S50, if the reproducibility of the reticle R by a reticle loader (not shown), that is, the positioning accuracy and the repeatability of the reticle R are lowered, the alignment mark RAM This is because there is a case where it is not possible to detect reliably. In particular, when the position information of the alignment mark RAM associated with the same drawing apparatus information as the drawing apparatus information in the identification information of the reticle R ₁ is read, the drawing error and reticle thickness error of the alignment mark RAM are read. In some cases, the alignment mark RAM cannot be reliably detected.
If it is determined that the alignment mark RAM could not be detected, as described above, the alignment mark RAM is detected using the low magnification alignment microscope 51 after step S12. To do.

If the alignment mark RAM can be detected, as shown in FIG. 6, alignment, exposure processing, and the like are performed again using the reticle R1 after reticle replacement (step S60). If further reticle replacement is required, the above-described processing is repeated.
As described above, after the reticle replacement, the alignment mark RAM can be detected only by the high magnification alignment microscope 52 without switching the low magnification alignment microscope 51 and the high magnification alignment microscope 52. In particular, when the low magnification alignment microscope 51 and the high magnification alignment microscope 52 are switched, the switching of the ND filter 7 becomes unnecessary, and therefore the throughput can be further reduced.

In the above-described embodiment, the case where the alignment mark RAM formed on the reticle R is detected and the alignment process is performed when the reticle R is replaced is described, but the present invention is not limited to this. For example, when the lot of the wafer W is changed, the alignment mark RAM may be detected again, alignment processing, and baseline measurement may be performed again for the same reticle R without exchanging the reticle R.
However, the reticle alignment (even if the wafer W is changed, until the predetermined allowable time (time set in advance by the user) elapses from the last reticle alignment (including RA measurement) using the reticle R. RA) and baseline measurement (BCHK) may be omitted. When the reticle position fluctuation or baseline fluctuation is small even between lots (for example, when the number of wafers W in one lot is small or the exposure processing time in one lot is short), the alignment mark again at the beginning of the lot By omitting RAM detection, alignment processing, and baseline measurement, throughput can be shortened.

  Note that the operation procedures shown in the above-described embodiment, or the shapes and combinations of the components are examples, and can be variously changed based on process conditions, design requirements, and the like without departing from the gist of the present invention. is there. For example, the present invention includes the following modifications.

In the present embodiment, the search mark RSM is detected by the low-magnification alignment microscope 51 and the position of the alignment mark RAM is indirectly obtained. However, the present invention is not limited to this. The position of the alignment mark RAM may be directly detected by the low magnification alignment microscope 51. Therefore, the search mark RSM may not be provided on the reticle R.
Further, although the case where a plurality of alignment mark RAMs are provided on the reticle R has been described, at least one pair may be sufficient. Moreover, it is not always necessary to make a pair. For example, one may be used. However, in that case, the alignment in the rotational direction may be insufficient.

  Further, although the case where the alignment mark RAM is provided in a region different from the circuit pattern PA of the reticle R has been described, the circuit pattern PA (or a part thereof) may be used as the alignment mark RAM.

  The use of the exposure apparatus is not limited to the exposure apparatus for manufacturing a semiconductor device. For example, an exposure apparatus for liquid crystal that exposes a liquid crystal display element pattern on a square glass plate or a thin film magnetic head Widely applicable to exposure apparatus.

  The light source of the exposure apparatus to which the present invention is applied includes not only KrF excimer laser (248 nm), ArF excimer laser (193 nm), F2 laser (157 nm), but also g-line (436 nm) and i-line (365 nm). Alternatively, EUV light can be used. Further, the magnification of the projection optical system may be not only a reduction system but also an equal magnification or an enlargement system.

  An exposure apparatus to which the present invention is applied assembles various subsystems including the constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection, and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  In addition, in the semiconductor device, the process of designing the function and performance of the device, the process of manufacturing a mask (reticle) based on this design step, the process of manufacturing a wafer from a silicon material, and the exposure apparatus of the above-described embodiment It is manufactured through a wafer processing process for exposing a pattern to a wafer, a device assembly process (including a dicing process, a bonding process, and a packaging process), an inspection process, and the like.

Conceptual diagram showing exposure equipment Figure showing a reticle stage with a reticle The figure which shows the wafer stage which placed the wafer Diagram showing alignment mark and VRA mark Conceptual diagram showing a VRA type reticle alignment system The figure explaining the method of measuring the position of the mark for alignment The figure which shows the mark for alignment and the mark for VRA detected by a reticle alignment system

Explanation of symbols

7 ND filter (adjustment means)
50 Detection device (position measuring device, mask position measuring unit)
51 Low-magnification alignment microscope (first measurement system)
52 (52X, 52Y) High magnification alignment microscope (second measurement system)
57 Neutral density filter (adjustment means)
C1 arithmetic unit (determination means, discrimination means, control means)
C2 storage unit (storage means)
RAM alignment mark (pattern)
RA reticle alignment system (alignment system)
L1 alignment light (illumination light)
PA circuit pattern R reticle (mask)
W Wafer (Substrate)
EL exposure light (exposure beam)
EX exposure equipment

Claims (15)

A first measurement system for observing a pattern formed on the mask;
A second measurement system having a narrower measurement field of view than the first measurement system, and observing the pattern at a measurement magnification higher than that of the first measurement system;
In a position measurement apparatus having a determination unit that determines a positional relationship between the measurement visual field of the second measurement system and the pattern based on the measurement result of the first measurement system,
Storage means for storing the position information of the pattern measured by the first measurement system in association with identification information for identifying a mask provided with the pattern;
Before measuring a pattern on a predetermined mask with the first measurement system, and having a determination unit that determines presence or absence of the identification information regarding the predetermined mask in the storage unit,
When the determination means determines that the storage means includes the identification information related to the predetermined mask, the determination means uses the position information corresponding to the predetermined mask stored in the storage means. A position measurement apparatus characterized by determining a positional relationship between a measurement visual field of the second measurement system and the pattern based on the position. A first measurement system for observing a pattern formed on the mask;
A second measurement system having a narrower measurement field of view than the first measurement system, and observing the pattern at a measurement magnification higher than that of the first measurement system;
In a position measurement apparatus having a determination unit that determines a positional relationship between the measurement visual field of the second measurement system and the pattern based on the measurement result of the first measurement system,
Storage means for storing the position information of the pattern measured by the first measurement system in association with the drawing apparatus information used when drawing the pattern on the mask;
Before measuring the pattern on the predetermined mask by the first measurement system, the reading device information on the predetermined mask is read, and the determination unit compares and determines the drawing device information stored in the storage unit. ,
When the determining means determines that the storage means has the same drawing apparatus information as the drawing apparatus information related to the predetermined mask, the determining means is the same drawing apparatus stored in the storage means A position measurement device that determines a positional relationship between a visual field range of the second measurement system and the pattern based on the position information corresponding to information. Based on the positional relationship determined by the determining means, further comprising position control means for driving the predetermined mask to control the relative positional relationship between the predetermined mask and the measurement visual field of the second measurement system;
When the position control unit performs position control of the predetermined mask based on the position information stored in the storage unit, and the pattern does not fall within the measurement field of view of the second measurement system. The position measuring apparatus according to claim 1, wherein the position on the predetermined mask is measured using the first measurement system. Means for adjusting the intensity of illumination light used when measuring on the mask using the first measurement system or the second measurement system;
The adjustment means does not optimize the intensity of the illumination light for the first measurement system when the measurement operation by the second measurement system is performed based on the stored position information. The position measuring device according to claim 1, wherein The first measurement system and the second measurement system for detecting light generated from the mask share a part of the measurement path up to an intermediate optical path branch point,
The adjusting means for adjusting the intensity of light generated from the mask is provided in at least one of the first measurement system and the second measurement system after the optical path branch point. The position measuring device according to any one of claims 1 to 4.   6. The position information of the pattern measured by the first measurement system and stored in the storage means includes a drawing error of the pattern on a mask. The position measuring device according to item. In an alignment apparatus that has a mask position measurement unit that measures the position of a mask on which a circuit pattern is formed, and that aligns the mask and a substrate onto which the circuit pattern is transferred,
An alignment apparatus using the position measurement apparatus according to claim 1 as the mask position measurement unit. In an exposure apparatus for transferring an image of the circuit pattern irradiated by an exposure beam onto the substrate after aligning the mask on which the circuit pattern is formed and the substrate,
An exposure apparatus using the alignment apparatus according to claim 7 as an apparatus for aligning the mask and the substrate. A first step of observing a pattern formed on the mask using a first measurement system;
A second step of storing the position information of the pattern measured by the first measurement system in association with identification information for identifying a mask provided with the pattern;
A third step of observing the pattern at a measurement magnification higher than that of the first measurement system using a second measurement system having a measurement field of view narrower than that of the first measurement system;
Before measuring the pattern on the predetermined mask with the first measurement system, the fourth step of determining the presence or absence of the identification information related to the predetermined mask in the information stored in the second step;
When the presence of the identification information related to the predetermined mask is recognized in the fourth step, based on the position information corresponding to the stored identification information, the measurement visual field of the second measurement system and the pattern And a fifth step of determining a positional relationship. A first step of observing a pattern formed on the mask using a first measurement system;
A second step of storing the position information of the pattern measured by the first measurement system in association with the drawing apparatus information used when drawing the pattern on the mask;
A third step of observing the pattern at a measurement magnification higher than that of the first measurement system using a second measurement system having a measurement field of view narrower than that of the first measurement system;
Before measuring the pattern on the predetermined mask by the first measurement system, the fourth step of reading the drawing device information about the predetermined mask and comparing and determining the drawing device information stored in the second step;
When the presence of the same drawing apparatus information as the drawing apparatus information related to the predetermined mask is recognized in the fourth step, the second measurement system is updated based on the position information corresponding to the stored drawing apparatus information. And a fifth step of determining a positional relationship between the measurement visual field and the pattern. A first step of observing a pattern formed on the mask using a first measurement system;
A second step of storing the position information of the pattern measured by the first measurement system in association with the drawing apparatus information used when drawing the pattern on the mask;
And a third step of observing the pattern at a measurement magnification higher than that of the first measurement system using a second measurement system having a narrower measurement field of view than the first measurement system,
If the information stored in the second step includes information on a mask to be measured later, the third step is performed using the stored information without going through the first step. A position measurement method characterized by performing.   In the second step, the position information of the pattern measured by the first measurement system is stored in association with the drawing apparatus information used when drawing the pattern on the mask. Item 12. The position measurement method according to Item 11. In an alignment method for measuring the position of a mask on which a circuit pattern is formed and aligning the mask and a substrate onto which the circuit pattern is transferred,
An alignment method using the position measurement method according to claim 9 as a mask position measurement method. In the exposure method of aligning the mask on which the circuit pattern is formed and the substrate, irradiating the mask with an exposure beam, and transferring an image of the circuit pattern onto the substrate,
An exposure method using the alignment method according to claim 13 as an alignment method between the mask and the substrate. 15. A device manufacturing method including a lithography process, wherein the exposure method according to claim 14 is used in the lithography process.

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