JP2010205896A - Method of measuring flare, and exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure information on flare over a wide range, such as long-distance flare. <P>SOLUTION: A method of measuring flare information of a projection optical system includes: a process for changing the shape of an exposure region 27W of exposure light applied to an image surface of the projection optical system; a process for measuring the amount of variation of the quantity of light in the exposure light via an irradiation amount monitor 29 where a light reception section 29a is installed at a measurement point on the image surface of the projection optical system while changing the shape of the exposure region 27W; and a process for obtaining the flare information, based on the shape of the exposure region 27W and measurement results of the amount of variation of the quantity of light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flare measurement method for measuring flare information of a projection optical system and an exposure method using the flare measurement method.

  In an exposure apparatus used in a photolithography process for manufacturing various devices (electronic devices) such as semiconductor devices, scattered light generated by the roughness of the surface of the optical member constituting the projection optical system is caused by the original light flux. If a flare as image blur is formed around the image to be imaged, the contrast of the image is lowered and the imaging characteristics are affected. Therefore, when evaluating the imaging characteristics of the projection optical system, it is necessary to measure the flare. Further, in an exposure apparatus (EUV exposure apparatus) that uses extreme ultraviolet light (Extreme Ultraviolet Light: hereinafter referred to as EUV light) as the exposure light, almost all of the optical members including the reticle are reflective members, and flare However, since the required resolution increases, flare needs to be measured with high accuracy.

  As a conventional flare measurement method, for example, an image of an evaluation pattern including an annular transmission part (or reflection part) is exposed through a projection optical system, and an exposure amount when the image of the transmission part is exposed, and There is known a Kirk method (Kirk method) for evaluating flare from a ratio to an exposure amount when the center of an image of a light shielding portion inside is exposed (for example, see Patent Document 1).

JP 2007-234716 A

  Flares include short-distance flare that spreads over a narrow area and long-distance flare that spreads outside the exposure area of the image plane of the projection optical system, and conventional flare measurement methods can easily measure short-distance flare. Long-distance flare is difficult to measure because the area of small light intensity extends far away. Long distance flare may also affect adjacent shot areas on the substrate being exposed. Therefore, in order to further increase the exposure accuracy in the future, it is necessary to accurately evaluate long-distance flare.

  In view of such circumstances, it is an object of the present invention to provide a flare measurement technique capable of accurately measuring flare information over a wide range such as a long-distance flare, and an exposure technique using the flare measurement technique.

  The flare measurement method according to the present invention is a method for measuring flare information of a projection optical system, and the step of changing the shape of an illumination area of illumination light irradiated on an object plane of the projection optical system or an image plane of the projection optical system. Measuring the amount of variation in the amount of illumination light at a measurement point on the image plane of the projection optical system while changing the shape of the illumination region, and determining the shape of the illumination region and the amount of variation in the amount of light. And determining the flare information based on the measurement result.

  An exposure method according to the present invention is an exposure method in which a pattern is formed on an object via a projection optical system, and the flare information of the projection optical system is measured using the flare measurement method of the present invention. Processing according to the measurement result is performed.

  According to the flare measurement method of the present invention, when the shape of the illumination area changes, the amount of light measured at the measurement point changes due to flare from the portion where the shape has changed. Therefore, flare can be accurately measured based on the measurement result of the light quantity at the measurement point.

It is sectional drawing which shows schematic structure of the exposure apparatus of an example of embodiment of this invention. (A) is a bottom view showing the configuration of the reticle blind of FIG. 1, (B) is a bottom view showing the pattern of the test reticle R1, (C) is a bottom view showing a first modification of the test reticle, (D). FIG. 10 is a bottom view showing a second modification of the test reticle. It is a flowchart which shows an example of the measurement operation | movement of the flare of a projection optical system. (A), (B), (C), and (D) are bottom views each showing an illumination region in which the width in the X direction is gradually narrowed. (A) is a plan view showing a state in which the light receiving unit of the dose monitor 29 is arranged in the exposure area 27W, and (B), (C), and (D) are exposure areas 27W in which the width in the X direction gradually decreases. It is a top view which shows the state which measures the flare of this with the irradiation amount monitor 29. FIG. It is a figure which shows an example of the relationship between the X direction width | variety of an exposure area | region, and the exposure amount measured with the irradiation amount monitor 29. (A) is a plan view showing a resist pattern in which an area corresponding to an exposure area other than the image of the light shielding pattern is exposed, and (B) is a plan view showing a resist pattern in which the area corresponding to the image of the light shielding pattern is also exposed. is there. It is a flowchart which shows an example of the manufacturing process of an electronic device.

An example of an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view schematically showing the overall configuration of the exposure apparatus 100 of the present embodiment. The exposure apparatus 100 uses EUV light (Extreme Ultraviolet Light) such as 11 nm or 13 nm as exposure light (exposure illumination light or exposure beam) EL within a wavelength range of about 100 nm or less and about 3 to 50 nm. Device. In FIG. 1, an exposure apparatus 100 includes a laser plasma light source 10 that generates a pulse of exposure light EL, and an illumination optical system ILS that illuminates a pattern surface (here, the lower surface) of a reticle R (mask) with an illumination region 27R. A reticle stage RST that moves the reticle R, and a projection optical system PO that projects an image of a pattern in the illumination area 27R of the reticle R onto a wafer W (photosensitive substrate) coated with a resist (photosensitive material). ing. Further, the exposure apparatus 100 includes a wafer stage WST that moves the wafer W, a main control system 31 that includes a computer that controls the overall operation of the apparatus, and the like.

In this embodiment, since EUV light is used as the exposure light EL, the illumination optical system ILS and the projection optical system PO are composed of reflective optical members such as a plurality of mirrors except for a specific filter or the like (not shown). The reticle R is also a reflection type. For example, the reflective optical member is obtained by processing a surface of a member made of quartz (or a metal having high heat resistance) into a predetermined curved surface or a plane with high accuracy, and then molybdenum (Mo) and silicon (Si) on the surface. A multilayer film (an EUV light reflecting film) is formed as a reflecting surface. The multilayer film may be another multilayer film in which a substance such as ruthenium (Ru) or rhodium (Rh) and a substance such as Si, beryllium (Be), or carbon tetraboride (B ₄ C) are combined. . The reticle R is formed, for example, by forming a multilayer film on the surface of a quartz substrate to form a reflective surface (reflective film), and on the reflective surface, tantalum (Ta), nickel (Ni), chromium (Cr), or the like. A transfer pattern is formed by an absorption layer made of a material that absorbs EUV light. A metal can also be used as the reticle R substrate.

Further, in order to prevent the EUV light from being absorbed by the gas, the exposure apparatus 100 is accommodated in the box-like vacuum chamber 1 as a whole, and the space in the vacuum chamber 1 is evacuated through the exhaust pipes 32Aa, 32Ba and the like. Large vacuum pumps 32A, 32B and the like are provided. Further, a plurality of sub-chambers (not shown) are provided in order to further increase the degree of vacuum on the optical path of the exposure light EL in the vacuum chamber 1. As an example, the pressure in the vacuum chamber 1 is about 10 ⁻⁵ Pa, and the pressure in the subchamber (not shown) that houses the projection optical system PO in the vacuum chamber 1 is about 10 ⁻⁵ to 10 ⁻⁶ Pa.

  Hereinafter, in FIG. 1, the Z axis is taken in the normal direction of the surface (bottom surface of the vacuum chamber 1) on which the wafer stage WST is placed, and a plane perpendicular to the Z axis (in this embodiment, a plane substantially parallel to the horizontal plane). In the following description, the X axis is perpendicular to the paper surface of FIG. 1 and the Y axis is parallel to the paper surface of FIG. In this embodiment, when the reticle R is irradiated with the exposure light EL, an illumination region 27R is formed on the reticle R. As shown in FIG. 2A, the illumination area 27R has an arc shape that is elongated in the X direction (non-scanning direction), and is axisymmetric with respect to a straight line parallel to the Y axis. During normal exposure, the reticle R and the wafer W are scanned in synchronism with the projection optical system PO in the Y direction (scanning direction).

  First, the laser plasma light source 10 includes a high-power laser light source (not shown), a condensing lens 12 that condenses laser light supplied from the laser light source through the window member 15 of the vacuum chamber 1, xenon, and the like. This is a gas jet cluster type light source including a nozzle 14 for ejecting a target gas and a condensing mirror 13 having a spheroidal reflection surface. For example, the exposure light EL pulse-emitted from the laser plasma light source 10 at a frequency of several kHz is condensed on the second focal point of the condenser mirror 13. The output of the laser plasma light source 10 (irradiation energy per unit time of the exposure light EL) is controlled by the exposure amount control system 33 under the control of the main control system 31.

  The exposure light EL condensed at the second focal point becomes a substantially parallel light beam via a concave mirror (collimator optical system) 21 and is incident on a first fly-eye optical system 22 composed of a plurality of mirrors. The exposure light EL reflected by the system 22 enters a second fly's eye optical system 23 composed of a plurality of mirrors. The pair of fly-eye optical systems 22 and 23 constitutes an optical integrator. The shape and arrangement of the mirror elements of the fly-eye optical systems 22 and 23 are disclosed in, for example, US Pat. No. 6,452,661.

  In FIG. 1, the reflecting surface of each mirror element of the first fly-eye optical system 22 is substantially conjugate with the pattern surface of the reticle R, and is in the vicinity of the reflecting surface of the second fly-eye optical system 23 (near the exit surface of the optical integrator). ), A substantial surface light source (a set of a large number of minute secondary light sources) having a predetermined shape is formed. That is, the surface on which the substantial surface light source is formed is the pupil plane of the illumination optical system ILS, and the illumination condition is set to normal illumination, annular illumination, dipole illumination, or An aperture stop 28 for switching to quadrupole illumination or the like is disposed.

  The exposure light EL that has passed through the aperture stop 28 enters the curved mirror 24, and the exposure light EL reflected by the curved mirror 24 is reflected by the concave mirror 25, and then is an arcuate illumination area on the pattern surface of the reticle R. 27R is illuminated in a superimposed manner with a uniform illuminance distribution obliquely from below. The curved mirror 24 and the concave mirror 25 constitute a condenser optical system. The illumination optical system ILS is configured including the concave mirror 21, the fly-eye optical systems 22 and 23, the aperture stop 28, the curved mirror 24, and the concave mirror 25. In this case, the exposure light EL from the laser plasma light source 10 Koehler-illuminates the first fly's eye optical system 22 and consequently the pattern surface of the reticle R. The illumination optical system ILS is not limited to the configuration shown in FIG. 1, and various other configurations are possible.

Further, in order to define the arcuate illumination area 27R, the first Y-axis blind 26Y1 that shields the outside of the edge portion in the −Y direction of the exposure light EL, and the + Y of the exposure light EL reflected by the illumination area 27R A second Y-axis blind 26 </ b> Y <b> 2 that shields the outside of the direction edge portion is provided.
Further, as shown in FIG. 2A, first and second X-axis blinds 26X1, 26X2 that define edge portions of the illumination area 27R in the −X direction and the + X direction are provided, and the X-axis blinds 26X1, 26X2 are provided. Can be independently moved in the X direction along a guide member 26G1, 26G2 by a drive mechanism (not shown) including a linear motor and a linear encoder for position measurement. The Y-axis blind 26Y1 defines an edge portion 27Ry1 in the −Y direction of the illumination area 27R. A drive mechanism (not shown) for opening and closing the Y-axis blinds 26Y1 and 26Y2 in the Y direction is also provided. The Y-axis blinds 26Y1, 26Y2, the X-axis blinds 26X1, 26X2, and the drive mechanism thereof constitute a reticle blind (variable field stop) that defines the position and width in the X direction of the illumination area 27R. The opening / closing operation of the reticle blind is controlled by a blind control system 34 under the control of the main control system 31.
The reticle blind of this embodiment forms an arc-shaped opening (slit).

  In FIG. 1, a reticle R is attracted and held on the bottom surface of a reticle stage RST via an electrostatic chuck RH. The reticle stage RST is moved along a guide surface parallel to the XY plane of the outer surface of the vacuum chamber 1 by the stage control system 35 based on the measurement value of a laser interferometer (not shown) and the control information of the main control system 31. For example, it is driven with a predetermined stroke in the Y direction via a drive system (not shown) composed of a magnetically levitated two-dimensional linear actuator, and is also driven in a small amount in the X direction and the rotation direction around the Z axis (θz direction). The The reticle R is installed in a space surrounded by the vacuum chamber 1 through an opening on the upper surface of the vacuum chamber 1. A partition 8 is provided so as to cover the reticle stage RST on the vacuum chamber 1 side, and the inside of the partition 8 is maintained at an atmospheric pressure between the atmospheric pressure and the atmospheric pressure in the vacuum chamber 1 by a vacuum pump (not shown).

  The exposure light EL reflected by the illumination area 27R of the reticle R travels to the projection optical system PO that forms a reduced image of the pattern on the object plane (first surface) on the image plane (second surface). As an example, the projection optical system PO is configured by holding six mirrors M1 to M6 with a lens barrel (not shown), and is non-telecentric on the object plane (pattern surface of the reticle R) side and has an image plane (wafer W Is a telecentric reflecting optical system on the surface side, and the projection magnification is a reduction magnification such as 1/4. The exposure light EL reflected by the illumination area 27R of the reticle R is reduced to a part of the pattern of the reticle R on the exposure area 27W (area conjugate to the illumination area 27R) on the wafer W via the projection optical system PO. Form.

  In the projection optical system PO, the exposure light EL from the reticle R is reflected upward (+ Z direction) by the first mirror M1, subsequently reflected downward by the second mirror M2, and then the third mirror M3. And reflected downward by the fourth mirror M4. Next, the exposure light EL reflected upward by the fifth mirror M5 is reflected downward by the sixth mirror M6 to form a partial image of the pattern of the reticle R on the wafer W. As an example, the projection optical system PO is a coaxial optical system in which the optical axes of the mirrors M1 to M6 overlap the optical axis AX in common, and an aperture stop AS is disposed in the vicinity of the pupil surface near the reflection surface of the mirror M2 or in the vicinity thereof. Has been. Further, between the mirror M6 and the wafer W, a pair of shielding plates 30Y1, 30Y2 in the Y direction and a pair of shielding plates in the X direction (not shown) for shielding flare generated by scattering in the projection optical system PO. ) Including a shielding mechanism. Note that the projection optical system PO does not have to be a coaxial optical system, and its configuration is arbitrary.

  Wafer W is attracted and held on wafer stage WST via electrostatic chuck WH. Wafer stage WST is arranged on a guide surface arranged along the XY plane. Wafer stage WST is driven by stage control system 35 via a drive system (not shown) composed of, for example, a magnetic levitation type two-dimensional linear actuator based on the measurement value of a laser interferometer (not shown) and control information of main control system 31. Then, it is driven with a predetermined stroke in the X direction and the Y direction, and is also driven in the θz direction or the like as necessary.

  In the vicinity of the wafer W on the wafer stage WST, an irradiation amount monitor 29 comprising a photoelectric sensor having sensitivity to EUV light such as a photodiode or a photomultiplier is installed, and the detection signal of the irradiation monitor 29 is the main control. It is supplied to the system 31. The light receiving portion 29a (see FIG. 5A) of the irradiation amount monitor 29 is, for example, a circle having a diameter of about 1 mm. The light receiving unit 29a may be a square of about 1 mm square. In addition to the dose monitor 29, a dose monitor (not shown) having a larger light receiving unit may be further provided.

  As an example, based on the measurement result of the irradiation monitor 29, the main control system 31 at the time of normal exposure causes the exposure amount control system so that the integrated exposure amount after scanning exposure falls within an allowable range at each point on the wafer W. The oscillation frequency and pulse energy of the laser plasma light source 10 are controlled via 33, and the scanning speed of the reticle stage RST (and wafer stage WST) is controlled via the stage control system 35. The main control system 31 is connected to a data processing system 36 for processing data relating to flare measurement. Further, an alignment system (not shown) for reticle R and wafer W is also provided.

During the exposure, the wafer W is arranged inside the partition 7 so that the gas generated from the resist on the wafer W does not adversely affect the mirrors M1 to M6 of the projection optical system PO. The partition 7 is formed with an opening through which the exposure light EL passes, and the space in the partition 7 is evacuated by a vacuum pump (not shown) under the control of the main control system 31.
During exposure of the wafer W, the illumination optical system ILS illuminates the reticle R with the arcuate illumination area 27R, and an image of the pattern in the illumination area 27R passes through the projection optical system PO into one shot area ( In a state of being exposed on the die, the reticle R and the wafer W are moved synchronously with respect to the projection optical system PO in the Y direction at a speed ratio according to the reduction magnification of the projection optical system PO. ). In this way, the pattern image of the reticle R is exposed to the shot area on the wafer W. Thereafter, the wafer stage WST is driven to move the wafer W stepwise in the X and Y directions, and then the pattern image of the reticle R is scanned and exposed on the next shot area on the wafer W. In this way, a pattern image of the reticle R is sequentially exposed to a plurality of shot areas on the wafer W by the step-and-scan method.

  Next, the flare of the projection optical system PO of this embodiment will be described. Scattered light that is a factor of flare in the projection optical system PO is caused by the surface roughness of the mirrors M1 to M6. The flare is, for example, several in the exposure area 27W on the image plane of the projection optical system PO. There are short-distance flare that spreads in the range from about μm to about 1 mm, and long-distance flare that spreads over a distance of, for example, about 1 mm or more on the image plane. In the present embodiment, shielding plates 30Y1, 30Y2, etc. are installed between the projection optical system PO and the wafer W in FIG. Therefore, among the scattered light (flares) generated at the ends of the mirror M6 closest to the wafer W of the projection optical system PO in the + Y direction and the −Y direction, the scattered light contacting the edge portions of the shielding plates 30Y1 and 30Y2 in the Y direction. Only scattered light inside ELa and ELb reaches the wafer W. Similarly, of the scattered light (flare) generated at the ends in the ± X direction of the mirror M6, only the scattered light inside the scattered light contacting the edge portion of the shielding plate (not shown) in the X direction is on the wafer W. To reach. Therefore, when an image of an edge of the shielding plates 30Y1, 30Y2, etc. by the scattered light ELa, ELb in the Y direction and scattered light (not shown) in the X direction is an image 30P, the image 30P is an area surrounding the exposure area 27W. Long-distance flare generated in the projection optical system PO does not spread outside the image 30P of the edge portion of the shielding plate.

  Therefore, in the present embodiment, a flare including a long-distance flare extending from the short side width of the exposure region 27W to a distance corresponding to the long side width is set as a measurement target. At the time of the flare measurement, the test reticle R1 of FIG. 2B is loaded on the reticle stage RST of FIG. 1 instead of the reticle R. The coordinate systems (X, Y) in FIGS. 2B, 2C, and 2D are coordinate systems on the bottom surface of the reticle stage RST in FIG.

  As shown in the bottom view of FIG. 2B, a rectangular area elongated in the X direction, for example, surrounded by the absorption layer PAB at the center of the pattern area of the test reticle R1 is a uniform reflection pattern 4 made of a reflection film. . The reflection pattern 4 is a region wider than the illumination region 27R by the exposure light EL in the X direction and the Y direction, and the reflection pattern 4 is set so as to cover the illumination region 27R during flare measurement. As an example, the width in the Y direction (scanning direction) of the exposure region 27W on the wafer conjugate with the illumination region 27R in a state where the reticle blind is fully opened in the X direction and the Y direction is about several millimeters, and the length in the X direction is 20 to 20 mm. It is about 30 mm. The shape of the reflection pattern 4 may be any shape as long as it is wider than the illumination region 27R. The entire pattern region of the test reticle R2 may be used as a reflection film, and the entire surface may be used as the reflection pattern 4. Good.

  In addition, a circular light shielding pattern 5 made of an exposure light absorption layer is formed at the center of the reflection pattern 4. The diameter of the light shielding pattern 5 is smaller than the width in the Y direction of the illumination area 27R when fully open, and the diameter of the image by the projection optical system PO of the light shielding pattern 5 is the light receiving portion 29a of the dose monitor 29 in FIG. It is set to be larger than the width of (see (A)). The center of the image of the light shielding pattern 5 by the projection optical system PO is a flare measurement point.

  Next, an example of an operation for measuring the flare of the projection optical system PO of the exposure apparatus 100 using the test reticle R1 will be described with reference to the flowchart of FIG. The operation of the exposure apparatus 100 at this time is controlled by the main control system 31. First, in step 101 of FIG. 3, the test reticle R1 of FIG. 2B is loaded on the reticle stage RST of FIG. 1, and alignment is performed using an alignment mark (not shown) of the test reticle R1. In the next step 102, the reticle stage RST is driven to align the center of the light shielding pattern 5 in the reflection pattern 4 of the test reticle R1 with the center of the illumination area 27R.

  In the next step 103, as shown in FIG. 4A, the X-axis blinds 26X1, 26X2 are driven to set the width in the X direction of the illumination area 27R to the maximum value rx1. At this stage, the illumination light 27R is not irradiated with the exposure light EL. During this measurement operation, the width of the illumination area 27R in the Y direction is fixed to the maximum value. In the next step 104, as shown in FIG. 5A, the wafer stage WST is driven so that the light receiving portion 29a of the dose monitor 29 is located inside the exposure area 27W and outside the image 5P of the light shielding pattern 5. Position in the region (exposure light EL irradiated portion or bright portion). Then, irradiation of the exposure light EL is started on the test reticle R1 through the reticle blind, and the exposure amount (for example, irradiation energy per unit time) EP0 of the bright portion of the exposure region 27W is measured by the irradiation amount monitor 29, and the measurement result Is supplied to the data processing system 36. In the subsequent measurement operation, when the exposure light EL is irradiated to the illumination area 27R (exposure area 27W), the exposure amount is controlled to be EP0.

  In the next step 105, the wafer stage WST is driven to move the center of the light receiving portion 29a of the dose monitor 29 to the center of the image 5P of the light shielding pattern in the exposure area 27W, as shown in FIG. Since the light receiving unit 29a is contained in the image 5P, the exposure amount measured by the irradiation amount monitor 29 after this is caused by flare. Further, when the width rx1 in the X direction of the illumination area 27R in FIG. 4A and the projection magnification β of the projection optical system PO are used, the width wx1 in the X direction of the exposure area 27W in FIG. rx1.

  In the next step 106, the exposure light EL is illuminated on the test reticle R1 through the reticle blind to form an illumination area 27R on the test reticle R1, and the exposure amount EPi in the image 5P of the light shielding pattern is formed by the irradiation amount monitor 29. (Here i = 1) is measured. Information on the width wx1 of the exposure region 27W and the measured exposure amount EP1 at this time is supplied to the data processing system 36. In the next step 107, it is determined whether or not the width of the illumination area 27R in the X direction has reached a predetermined lower limit value (for example, twice the minimum value of the distance over which the flare to be measured spreads). At this stage, since the width in the X direction of the illumination area 27R is considerably wider than the lower limit value, the operation shifts to step 108, and the main control system 31 passes through the blind control system 34 in FIG. The blinds 26X1 and 26X2 are driven symmetrically to narrow the width of the illumination area 27R in the X direction symmetrically by Δrx. As a result, as shown in FIG. 4B, the width of the illumination region 27R in the X direction is rx2. Thereafter, the operation returns to step 106, and the illumination area 27R is illuminated with the exposure light EL. As shown in FIG. 5C, the exposure amount in the image 5P in the exposure area 27W having the width wx2 by the irradiation amount monitor 29. EPi (here, i = 2) is measured, and information on the width wx2 of the exposure region 27W and the measured exposure amount EP2 at this time is supplied to the data processing system 36.

  Thereafter, the operations in steps 108 and 106 are repeated, and the width in the X direction of the illumination region 27R is changed to the width rx3 in FIG. 4C, the rxi in FIG. As shown in FIG. 5E, the exposure amount EP3, EPi, etc. in the image 5P in the exposure region 27W such as the widths wx3 and wxi are measured by the dose monitor 29, and the measurement result is sent to the data processing system 36. Supply. In step 107, when the width of the illumination area 27R reaches the lower limit value, the operation proceeds to step 109, and the data processing system 36 measures the width wxi in the X direction of the exposure area 27W at this time. The flare of the projection optical system PO is obtained using the exposure amount EPi.

  In this case, the width wx in the X direction of the exposure region 27W and the exposure amount EP on the image 5P in the exposure region 27W have a relationship as shown by the dotted curve 41 in FIG. A plurality of points of wxi and exposure amount EPi (i = 1, 2,...) are measurement data. As an example, the data processing system 36 calculates the exposure amount ΔEPi caused by the exposure light EL that is incident on the region between the region of the exposure region 27 </ b> W whose width in the X direction is wxi and the region whose width is wx (i−1). It asks as follows.

ΔEPi = EPi−EP (i−1) (1)
In this case, since the exposure amount for the region other than the image 5P in the exposure region 27W is EP0, the data processing system 36 uses the exposure amount ΔEPi of Expression (1) for each width wxi of the exposure region 27W to To calculate the flare.
Flare = (ΔEPi / EP0) × 100 (%) (2)
When wxi−wx (i−1) is Δwx, when the width of the exposure region 27W in the X direction is wxi, the exposure light EL that enters the portion of the width Δwx inward from there. Represents a flare including a long-distance flare caused by. The flare measurement result is supplied to the main control system 31. In the next step 110, the main control system 31, for example, makes an operator call or the like as an example, and instructs to adjust the positions of the shielding plates 30Y1, 30Y2, etc. according to the flare. That is, for example, when there are many long-distance flare that is a large flare that is a flare when the width of the exposure area 27W is wide, a shot area adjacent to the shot area of the wafer W is slightly exposed during scanning exposure. Therefore, in order to reduce such unnecessary exposure, the interval between shielding plates (not shown) in the X direction may be narrowed. Thereby, the measurement of the flare including the long distance flare of the projection optical system PO is completed.

Thus, by measuring the change in the exposure amount in the exposure region 27W while narrowing the width of the illumination region 27R in the X direction, the long-distance flare of the projection optical system PO can be efficiently performed without actually performing exposure. Etc. can be measured accurately.
Note that a change in exposure amount may be measured within the exposure region 27W while gradually increasing the width of the illumination region 27R in the X direction.

Effects and the like of this embodiment are as follows.
(1) The flare measurement method of the projection optical system PO of the exposure apparatus 100 according to the present embodiment uses the shape of the illumination area 27R of the exposure light EL irradiated to the object plane of the projection optical system PO (and thus the shape of the exposure area 27W). The exposure amount (light amount) of the exposure light EL by the irradiation amount monitor 29 in which the light receiving portion 29a is installed on the measurement point on the image plane of the projection optical system PO while changing the shape of the illumination area 27R while step 108 is changed. ) Including a step 106 of measuring a variation amount of EPi, and a step 109 of obtaining the flare based on the shape of the exposure region 27W corresponding to the shape of the illumination region 27R and the measurement result of the variation amount of the exposure amount EPi. Yes.

According to this flare measurement method, when the shape of the illumination area 27R changes, the exposure amount measured at the measurement point changes due to flare from the portion where the shape has changed. Therefore, flare such as long-distance flare can be accurately measured based on the measurement result of the exposure amount at the measurement point.
In this embodiment, the flare is monitored by the dose monitor 29 inside the exposure area 27W. However, the flare may be monitored on a measurement point outside the exposure area 27W.

  (2) The illumination area 27R has an arc shape elongated in the X direction, and in step 108 for changing the shape of the illumination area 27R, the length in the X direction (longitudinal direction) is changed from the first length to the second length. In step 109 for obtaining the flare, the flare caused by the exposure light EL from the region between the first length and the second length of the illumination region 27R is determined from the measurement result of the exposure amount variation. Looking for ingredients. Accordingly, the flare caused by the exposure light EL incident on the X region of the illumination region 27R (exposure region 27W) can be obtained for each region having a predetermined width in the X direction.

  (3) Also, the outer shape of the illumination area 27R (exposure area 27W) is orthogonal to the X direction and is parallel to the Y axis through the line segment in the illumination area 27R (the center of the light shielding pattern 5 in FIG. 2B). The measurement point of the exposure amount is on the image 5P of the light shielding pattern 5 on the line segment optically conjugate with the line segment with respect to the projection optical system PO. Accordingly, flare from both sides in the longitudinal direction of the illumination area 27R can be measured collectively.

  (4) Further, in the illumination area 27R, an area having a large amount of reflection of the exposure light EL (an area other than the light shielding pattern 5 of the reflection pattern 4 of the test reticle R1) and a light shielding pattern 5 having a small amount of reflection of the exposure light EL Is set, and the center (exposure amount or flare measurement point) of the light receiving portion 29a of the irradiation amount monitor 29 is set in the image 5P conjugate with the light shielding pattern 5. Therefore, flare can be measured with a high SN ratio.

  Instead of the test reticle R1, a test reticle R2 in which the light shielding pattern 5 is off the center on the reflection pattern 4 may be used as shown in FIG. In this case, the flare is measured at a measurement point at a position shifted in the X direction from the center on the exposure region 27W. Further, instead of the test reticle R1, as shown in FIG. 2D, a test reticle R3 in which only the reflection pattern 4 without the light shielding pattern 5 is formed may be used. In this case, the flare measurement point on the image plane of the projection optical system PO may be arranged at any position on the exposure area 27W, and the measurement point is outside the exposure area 27W and shown in FIG. You may arrange | position in the arbitrary positions inside the image 30P of the edge part of a shielding board.

(5) In the above-described embodiment, since the EUV exposure apparatus is used, the test reticle R1 is a reflection type, and the pattern is formed of a reflection film and an absorption film for EUV light.
When the test reticle R1 is used as a transmissive reticle of an exposure apparatus that uses exposure light having a wavelength of 193 nm, for example, the test reticle is provided on a substrate that transmits exposure light and a surface of the substrate as an example. The pattern corresponding to the reflection pattern 4 is formed as a transmission pattern in which a part of the light shielding film is removed.

  (6) The exposure method of the present embodiment is an exposure method in which the pattern of the reticle R is illuminated with the exposure light EL, and the wafer W is exposed with the exposure light EL through the pattern and the projection optical system PO. Steps 101 to 109 for measuring the flare information of the projection optical system PO by the form flare measurement method, and step 110 for adjusting the positions of the shielding plates 30Y1, 30Y2, etc. based on the measurement result of the flare information are included. . Therefore, even if the flare of the projection optical system PO exists, the target pattern can be formed on the wafer W while suppressing the influence.

Instead of adjusting the positions of the shielding plates 30Y1, 30Y2, etc., the size of the opening formed by the shielding plates 30Y1, 30Y2 may be changed.
Further, instead of adjusting the position of the shielding plates 30Y1 and 30Y2 and the size of the opening, or together with the adjustment, the influence of the flare is reduced on the wafer W according to the measurement result of the flare of the projection optical system PO. The shape such as the line width of the pattern formed on the reticle R may be corrected so that a desired pattern is formed. That is, the reticle design may be corrected in consideration of the optical proximity effect.
In the present embodiment, the shielding mechanism including the shielding plates 30Y1 and 30Y2 and the pair of shielding plates in the X direction may be omitted. By doing so, it is possible to measure a wide range of flare that is not blocked by the shielding plates 30Y1 and 30Y2 and the pair of shielding plates in the X direction.

In the above embodiment, since the flare is measured using the dose monitor 29, the measurement time can be shortened. However, flare can be obtained by actually performing exposure (test print) as follows.
That is, for example, when measuring the flare in the image 5P in the exposure region 27W of FIG. 5B, the exposure amount is changed in various ways so that different positions on the unexposed wafer coated with the resist are changed. Exposure is performed in the exposure area 27W. Further, after the wafer is developed, first, as shown in FIG. 7A, when the resist pattern 27WR corresponding to the exposure region 27W is first formed (the resist pattern 5PR corresponding to the image 5P remains). ) And an exposure amount EW2 when the resist pattern 5PR corresponding to the image 5P disappears, as shown in FIG. 7B. And the flare at this time can be calculated | required from following Formula.

Flare = (EW1 / EW2) × 100 (%) (3)
Similarly, the flare is obtained by such a test print for the exposure region 27W shown in FIGS. 5C to 5E, and the difference of the obtained flare is calculated, whereby the X of the exposure region 27W is calculated. The flare caused by the exposure light EL incident on the region having the predetermined width in the direction can be obtained.

In the embodiment of FIG. 1, the case where the EUV light is used as the exposure beam and the all reflection projection optical system including only six mirrors is used is described as an example. For example, in addition to an exposure apparatus having a projection optical system composed of only four mirrors or the like, a VUV light source having a wavelength of 100 to 160 nm, for example, an Ar ₂ laser (wavelength 126 nm) is used as a light source, and 4 to 8 mirrors are used. The present invention can also be applied to an exposure apparatus equipped with a projection optical system.

Furthermore, the present invention can also be applied to a case where a projection optical system composed of a refractive system using ArF excimer laser light (wavelength 193 nm) or the like as exposure light is used.
When an electronic device (or microdevice) such as a semiconductor device is manufactured using the exposure method or exposure apparatus of the above embodiment, the electronic device has a function / performance design of the electronic device as shown in FIG. Step 221 to be performed; Step 222 for manufacturing a mask (reticle) based on this design step; Step 223 for manufacturing a substrate (wafer) that is a base material of the device and applying a resist; A substrate processing step 224 including a step of exposing a reticle pattern to a substrate (sensitive substrate) by an apparatus, a step of developing the exposed substrate, a heating (curing) and etching step of the developed substrate, a device assembly step (dicing step, (Including processing processes such as bonding and packaging) And an inspection step 226, etc..
Therefore, in this device manufacturing method, a pattern of the photosensitive layer is formed on the substrate using the exposure method or exposure apparatus of the above embodiment, and the substrate on which the pattern is formed is processed (step 224). Is included. According to the exposure method or the exposure apparatus, since the influence of flare of the projection optical system can be reduced, an electronic device can be manufactured with high accuracy.

In addition, the present invention is not limited to application to a semiconductor device manufacturing process. For example, a manufacturing process of a display device such as a liquid crystal display element or a plasma display formed on a square glass plate, or an imaging element (CCD, etc.), micromachines, MEMS (Microelectromechanical Systems), thin film magnetic heads, various devices such as DNA chips, and masks themselves can be widely applied to the manufacturing process.
In addition, this invention is not limited to the above-mentioned embodiment, A various structure can be taken in the range which does not deviate from the summary of this invention.

  ILS ... illumination optical system, R ... reticle, R1 ... test reticle, PO ... projection optical system, W ... wafer, M1-M6 ... mirror, 4 ... reflection pattern, 5 ... light shielding pattern, 26X1, 26X2 ... X-axis blind, 26Y1 , 26Y2 ... Y-axis blind, 27R ... illumination area, 27W ... exposure area, 30Y1, 30Y2 ... shielding plate

Claims (9)

In a method for measuring flare information of a projection optical system,
Changing the shape of the illumination area of illumination light applied to the object plane of the projection optical system or the image plane of the projection optical system;
Measuring the amount of fluctuation of the illumination light at a measurement point on the image plane of the projection optical system while changing the shape of the illumination area;
Obtaining the flare information based on the shape of the illumination area and the measurement result of the amount of change in the light amount;
A flare measurement method comprising: The illumination area is elongated;
When changing the shape of the illumination area, the length of the illumination area in the longitudinal direction is changed from the first length to the second length,
The step of obtaining the flare information obtains a flare component caused by the illumination light from a region between the first length and the second length of the illumination region from a measurement result of the amount of change in the light amount. The flare measurement method according to claim 1, wherein: The illumination area is an area on the object plane;
The outer shape of the illumination area is orthogonal to its longitudinal direction and is line symmetric with respect to a line segment in the illumination area;
The flare measurement method according to claim 2, wherein the measurement point is on a line segment optically conjugate with the line segment with respect to the projection optical system. The illumination area is an area on the object plane;
In the illumination area, a first area where the amount of illumination light passing is large and a second area where the amount of illumination light passing is small are set,
4. The flare measurement method according to claim 1, wherein the measurement point is arranged in a region on the image plane conjugate with the second region with respect to the projection optical system. 5. .   5. The step of measuring the amount of fluctuation of the amount of illumination light at the measurement point includes the step of measuring the amount of illumination light through a photoelectric sensor at the measurement point. The flare measurement method according to any one of the above. The step of changing the shape of the illumination area and measuring the amount of fluctuation in the amount of illumination light is:
Placing a photosensitive substrate on the image plane, setting the shape of the illumination area, and exposing different areas on the photosensitive substrate while changing the exposure amount of the illumination light; and
After developing the photosensitive substrate, the exposure amount when the region on the image plane optically conjugate with the first region is exposed to the projection optical system and the region corresponding to the measurement point are exposed. The flare measurement method according to claim 4, further comprising a step of obtaining a ratio with the exposure amount when being performed, and obtaining a light amount at the measurement point based on the ratio.   The flare measurement method according to claim 1, wherein the projection optical system is a reflection system that uses EUV light as the illumination light. In an exposure method for forming a pattern on an object via a projection optical system,
Measure flare information of the projection optical system using the flare measurement method according to any one of claims 1 to 7,
An exposure method that performs processing according to the measurement result of the flare information.   When exposing the object, the elongated illumination area on the mask pattern is illuminated with illumination light, and an image of the pattern in the illumination area is projected onto the object via the projection optical system. The exposure method according to claim 8, wherein the object is moved synchronously with respect to the projection optical system.

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