Exposure method and method for manufacturing electronic device

Abstract

This exposure method comprises: a first step in which, on the basis of a measurement result relating to a positional displacement of an exposure result of pre-exposure using an exposure device, the wavelength of first pulse laser light for scanning a first scan field of a first semiconductor wafer is set to a first pattern that changes according to an in-field position along a scan direction in the first scan field, and the wavelength of second pulse laser light for scanning a second scan field of the first semiconductor wafer is set to a second pattern different from the first pattern that changes according to an in-field position along a scan direction in the second scan field; and a second step for scanning the first scan field with the first pulse laser light and thereafter scanning the second scan field with the second pulse laser light using the exposure device.

Description

Exposure method and method for manufacturing electronic device

[0001] The present disclosure relates to an exposure method and a method for manufacturing an electronic device.

[0002] In recent years, semiconductor exposure apparatuses have been required to improve their resolution in response to the miniaturization and high integration of semiconductor integrated circuits. To this end, the wavelength of light emitted from exposure light sources has been shortened. For example, KrF excimer laser devices that output laser light with a wavelength of approximately 248 nm and ArF excimer laser devices that output laser light with a wavelength of approximately 193 nm are used as gas laser devices for exposure.

[0003] The spectral linewidth of the spontaneously oscillating light from KrF excimer laser devices and ArF excimer laser devices is as wide as 350 to 400 pm. Therefore, if a projection lens is constructed using a material that transmits ultraviolet light, such as KrF and ArF laser light, chromatic aberration may occur. As a result, resolution may be reduced. Therefore, it is necessary to narrow the spectral linewidth of the laser light output from the gas laser device to a level where chromatic aberration is negligible. Therefore, a line narrowing module (LNM) containing a line narrowing element (e.g., an etalon or grating) may be installed within the laser resonator of the gas laser device to narrow the spectral linewidth. A gas laser device with a narrowed spectral linewidth is called a line narrowing gas laser device.

[0004] US Patent Application Publication No. 2007 / 0273851 US Patent Application Publication No. 2006 / 0114437 JP 2009-231564 A US Patent Application Publication No. 2010 / 0092881 US Patent Application Publication No. 2012 / 0154806 US Patent Application Publication No. 2011 / 0216294 overview

[0005] An exposure method according to one aspect of the present disclosure includes a first step of setting the wavelength of a first pulsed laser beam used to scan a first scan field of a first semiconductor wafer to a first pattern that varies depending on the position within the field along the scan direction in the first scan field, and setting the wavelength of a second pulsed laser beam used to scan a second scan field of the first semiconductor wafer to a second pattern that varies depending on the position within the field along the scan direction in the second scan field and is different from the first pattern, based on measurement results regarding the positional deviation of the exposure result due to pre-exposure using an exposure apparatus; and a second step of scanning the first scan field with the first pulsed laser beam using an exposure apparatus, and then scanning the second scan field with the second pulsed laser beam.

[0006] A method for manufacturing an electronic device according to one aspect of the present disclosure includes a first step of setting the wavelength of a first pulsed laser beam for scanning a first scan field of a first semiconductor wafer to a first pattern that varies depending on the position in the field along the scan direction in the first scan field, and setting the wavelength of a second pulsed laser beam for scanning a second scan field of the first semiconductor wafer to a second pattern that varies depending on the position in the field along the scan direction in the second scan field and is different from the first pattern, based on measurement results regarding misalignment of an exposure result by pre-exposure using an exposure apparatus; and a second step of scanning the first scan field with the first pulsed laser beam using an exposure apparatus, and then scanning the second scan field with the second pulsed laser beam, to manufacture an electronic device.

[0007] Some embodiments of the present disclosure are described below, by way of example only, with reference to the accompanying drawings. FIG. 1 schematically illustrates the configuration of an exposure system in a comparative example. FIG. 2 schematically illustrates the configuration of an exposure system in a comparative example. FIG. 3, together with FIGS. 4 and 5, illustrates how the position of a scan field of a semiconductor wafer changes relative to the position of the beam cross section of a pulsed laser beam. FIG. 4, together with FIGS. 3 and 5, illustrates how the position of a scan field of a semiconductor wafer changes relative to the position of the beam cross section of a pulsed laser beam. FIG. 5, together with FIGS. 3 and 4, illustrates how the position of a scan field of a semiconductor wafer changes relative to the position of the beam cross section of a pulsed laser beam. FIG. 6 schematically illustrates the configuration of an exposure system in a first embodiment. FIG. 7 is a flowchart illustrating a wavelength correction process according to the first embodiment. FIG. 8 illustrates the entire pre-exposed wafer or semiconductor wafer and details of a portion thereof. FIG. 9 is a flowchart illustrating details of a process for calculating the amount of change in wavefront aberration with respect to a change in wavelength. FIG. 10 is a flowchart illustrating details of a process for calculating the amount of change in positional deviation with respect to a change in wavefront aberration. FIG. 11 is a flowchart illustrating details of a process for calculating a wavelength correction amount corresponding to a measured overlay error. FIG. 12 shows a method for converting a subscript i identifying a semiconductor wafer and a subscript j identifying a scan field into an elapsed time t from the start of exposure. FIG. 13 shows a plot of wavelength correction amounts corresponding to measured overlay errors. FIG. 14 shows an example of a model obtained by fitting the wavelength correction amounts to an exponential function. FIG. 15 shows an example of a model created for each subscript k. FIG. 16 shows an example of a change pattern of the wavelength of the pulsed laser light that scans the scan field. FIG. 17 is a flowchart showing wavelength correction processing according to the second embodiment. FIG. 18 shows a method for converting a subscript i identifying a semiconductor wafer and a subscript j identifying a scan field into an elapsed time t from the start of exposure. FIG. 19 shows a plot of measured overlay errors. FIG. 20 shows an example of a model obtained by fitting the overlay errors to an exponential function. FIG. 21 is a flowchart showing details of processing for calculating wavelength correction amounts for all semiconductor wafers.Fig. 22 shows an example of the wavelength correction amount calculated in S704. Fig. 23 shows an example of the change pattern of the wavelength of the pulsed laser beam that scans the scan field. Embodiment

[0008] <Contents> 1. Comparative Example 1.1 Exposure System 1.2 Exposure Apparatus 200 1.2.1 Configuration 1.2.2 Operation 1.3 Laser Apparatus 100 1.3.1 Configuration 1.3.2 Operation 1.4 Line Narrowing Module 14 1.4.1 Configuration 1.4.2 Operation 1.5 Scanning Exposure 1.6 Issues with the Comparative Example 2. Exposure System Generating Chromatic Aberration 2.1 Configuration 2.2 Operation 2.2.1 Wavefront Aberration W 2.2.2 Main Flow 2.2.3 dZ ｎｐ Calculation of / dλ 2.2.4 ∂E ｇ / ∂Z ｎ 2.2.5 Calculation of the measured overlay error D ｉｊｋｐｇ The wavelength correction amount Δλ corresponding to ｉｊｋ 2.2.6 Calculation of wavelength correction amount Δλ for all semiconductor wafers WF ｉｊｋ 2.2.7 Relationship between wavelength fluctuation within the scan field SF and wavelength fluctuation according to elapsed time t 2.3 Action 3. Overlay error D ｉｊｋｐｇ 3.1 Operation 3.1.1 Main flow 3.1.2 Overlay error D of all semiconductor wafers WF ｉｊｋｐｇ 3.1.3 Determination of wavelength correction amount Δλ for all semiconductor wafers WF ｉｊｋ Calculation of 3.2 Action 4. Other

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Furthermore, not all of the configurations and operations described in each embodiment are necessarily essential as the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and redundant explanations will be omitted.

[0010] 1 and 2 show schematic diagrams of the configuration of an exposure system in a comparative example. The comparative example in the present disclosure is a configuration that the applicant recognizes as being known only by the applicant, and is not a publicly known example that the applicant acknowledges.

[0011] The exposure system includes a laser apparatus 100 and an exposure apparatus 200. The laser apparatus 100 is shown in a simplified form in Fig. 1. The exposure apparatus 200 is shown in a simplified form in Fig. 2.

[0012] The laser apparatus 100 includes a laser control processor 130. The laser apparatus 100 is configured to output a pulsed laser beam toward the exposure apparatus 200.

[0013] 1.2 Exposure Apparatus 200 1.2.1 Configuration As shown in FIG. 1, the exposure apparatus 200 includes an illumination optical system 201 , a projection optical system 202 , and an exposure control processor 210 .

[0014] The illumination optical system 201 illuminates a reticle pattern of a reticle (not shown) placed on a reticle stage RT with pulsed laser light incident from the laser device 100 .

[0015] The projection optical system 202 reduces and projects the pulsed laser light that has passed through the reticle, forming an image on a workpiece (not shown) placed on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a resist film.

[0016] The exposure control processor 210 is a processing device that includes a memory 212 in which a control program is stored, and a CPU (central processing unit) 211 that executes the control program. The exposure control processor 210 is specially configured or programmed to execute various processes included in the present disclosure. The exposure control processor 210 manages the overall control of the exposure apparatus 200, and transmits and receives various data and signals to and from the laser control processor 130.

[0017] 1.2.2 Operation The exposure control processor 210 sets various parameters related to exposure conditions and controls the illumination optical system 201 and the projection optical system 202 .

[0018] The exposure control processor 210 transmits data on the target wavelength value and a trigger signal to the laser control processor 130. The laser control processor 130 controls the laser device 100 in accordance with this data and signal.

[0019] The exposure control processor 210 synchronizes the reticle stage RT and the workpiece table WT and translates them in opposite directions, thereby exposing the workpiece to pulsed laser light that reflects the reticle pattern.

[0020] The reticle pattern is transferred onto the semiconductor wafer through this exposure process, after which electronic devices can be manufactured through multiple processes.

[0021] 2, the laser apparatus 100 includes a laser control processor 130, as well as a laser chamber 10, a pulsed power module (PPM) 13, a line narrowing module 14, an output coupling mirror 15, and a monitor module 17. The line narrowing module 14 and the output coupling mirror 15 form an optical resonator.

[0022] The laser chamber 10 is disposed in the optical path of the optical resonator and is provided with windows 10a and 10b.

[0023] The laser chamber 10 includes an electrode 11a and a pair of electrodes (not shown) therein, and further contains a laser gas containing components of a laser medium. ２ , ArF, KrF, XeCl, or XeF.

[0024] The pulse power module 13 includes a switch (not shown) and is connected to a charger (not shown).

[0025] The line narrowing module 14 includes prisms 41 to 43, a grating 53, and a mirror 63. The line narrowing module 14 will be described in detail later.

[0026] The output coupling mirror 15 is composed of a partial reflection mirror. A beam splitter 16 that transmits part of the pulsed laser light with high transmittance and reflects the other part is disposed in the optical path of the pulsed laser light output from the output coupling mirror 15. A monitor module 17 is disposed in the optical path of the pulsed laser light reflected by the beam splitter 16.

[0027] The laser control processor 130 is a processing device that includes a memory 132 that stores a control program and a CPU 131 that executes the control program. The laser control processor 130 is specially configured or programmed to perform the various processes included in this disclosure.

[0028] 1.3.2 Operation The laser control processor 130 acquires data on the wavelength target value from the exposure control processor 210. The laser control processor 130 transmits an initial setting signal to the line narrowing module 14 based on the wavelength target value. After the output of the pulsed laser light starts, the laser control processor 130 receives wavelength measurement data from the monitor module 17 and transmits a feedback control signal to the line narrowing module 14 based on the wavelength target value and the wavelength measurement data.

[0029] The laser control processor 130 receives a trigger signal from the exposure control processor 210. The laser control processor 130 transmits an oscillation trigger signal based on the trigger signal to the switch of the pulse power module 13.

[0030] The switch is turned on when it receives an oscillation trigger signal from the laser control processor 130. When the switch is turned on, the pulse power module 13 generates a pulsed high voltage from the electrical energy stored in the charger. The pulse power module 13 applies this high voltage to the electrode 11a.

[0031] When a high voltage is applied to electrode 11a, a discharge occurs between electrode 11a and its paired electrode. The energy of this discharge excites the laser gas in laser chamber 10 and causes it to transition to a higher energy level. When the excited laser gas subsequently transitions to a lower energy level, it emits light with a wavelength corresponding to the difference in energy levels.

[0032] Light generated within the laser chamber 10 is emitted to the outside of the laser chamber 10 through windows 10a and 10b. The light emitted from the window 10a enters the line narrowing module 14 as a light beam. Of the light that enters the line narrowing module 14, light having a wavelength near the desired wavelength is reflected by the line narrowing module 14 and returned to the laser chamber 10.

[0033] The output coupling mirror 15 transmits and outputs a portion of the light emitted from the window 10 b , and reflects the other portion back into the laser chamber 10 .

[0034] In this way, the light emitted from the laser chamber 10 travels back and forth between the line-narrowing module 14 and the output coupling mirror 15. This light is amplified each time it passes through the discharge space between the electrode 11a and its paired electrode. The light thus oscillated and line-narrowed is output as pulsed laser light from the output coupling mirror 15 and enters the exposure device 200.

[0035] 1.4 Line Narrowing Module 14 1.4.1 Configuration Prisms 41 to 43 are arranged in the optical path of the light beam emitted from window 10 a in ascending order of their numbers. Prism 43 can be rotated around an axis perpendicular to the paper surface of FIG. 2 by a rotation stage 143.

[0036] Mirror 63 is disposed in the optical path of the light beam that has passed through prisms 41 to 43. Mirror 63 can be rotated around an axis perpendicular to the plane of the paper in Fig. 2 by a rotation stage 163. Grating 53 is disposed in the optical path of the light beam that has been reflected by mirror 63.

[0037] 1.4.2 Operation The light beam emitted from the window 10a is expanded in beam width by each of the prisms 41 to 43 in a plane parallel to the plane of the paper in Fig. 2. The light beam transmitted through the prisms 41 to 43 is reflected by the mirror 63 and enters the grating 53.

[0038] The light beam incident on the grating 53 is reflected by the multiple grooves of the grating 53 and diffracted in a direction according to the wavelength of the light. The grating 53 is in a Littrow configuration so that the angle of incidence of the light beam incident on the grating 53 from the mirror 63 matches the diffraction angle of the diffracted light of the desired wavelength.

[0039] The mirror 63 and the prisms 41 to 43 reduce the beam width of the light beam returned from the grating 53 in a plane parallel to the paper surface of FIG. 2, and return the light beam to the inside of the laser chamber 10 through the window 10a.

[0040] The laser control processor 130 controls the rotation stages 143 and 163 via a driver (not shown). The angle of incidence of the light beam incident on the grating 53 changes depending on the rotation angle of the rotation stages 143 and 163, and the wavelength selected by the line narrowing module 14 changes.

[0041] 1.5 Scanning Exposure The exposure of the semiconductor wafer with pulsed laser light is performed for each section called a scan field SF. A scan field SF is an area where some of the many semiconductor chips formed on the semiconductor wafer are formed, and corresponds to an area where the reticle pattern of one reticle is transferred in one scan.

[0042] 3 to 5 show how the position of the scan field SF on the semiconductor wafer changes relative to the position of the beam cross section B of the pulsed laser light. The direction in which the position of the scan field SF changes is the Y-axis direction, and the direction perpendicular to the Y-axis direction is the X-axis direction.

[0043] The width of the scan field SF in the X-axis direction corresponds to the width of the beam cross section B of the pulsed laser beam in the X-axis direction at the position of the workpiece table WT (see FIG. 1 ), and the width of the scan field SF in the Y-axis direction is greater than the width of the beam cross section B of the pulsed laser beam in the Y-axis direction at the position of the workpiece table WT.

[0044] The procedure for scanning and exposing each scan field SF in the Y-axis direction with pulsed laser light is performed in the order shown in FIGS. 3, 4, and 5. First, as shown in FIG. 3, the workpiece table WT is positioned so that the +Y-direction end SFy+ of the scan field SF is located a predetermined distance in the -Y direction relative to the position of the -Y-direction end By- of the beam cross section B. Then, the workpiece table WT is accelerated in the +Y direction to a speed V until the +Y-direction end SFy+ of the scan field SF coincides with the position of the -Y-direction end By- of the beam cross section B. As shown in FIG. 4, the scan field SF is exposed while the workpiece table WT is moved in the +Y direction so that the position of the scan field SF moves linearly at a constant speed V relative to the position of the beam cross section B. As shown in FIG. 5, the scanning of the scan field SF is completed when the workpiece table WT is moved until the -Y-direction end SFy- of the scan field SF passes the position of the +Y-direction end By+ of the beam cross section B.

[0045] 1.6 Issues with the Comparative Example In the manufacture of electronic devices, multiple layers constituting a semiconductor chip are stacked and exposed. To manufacture electronic devices that function as designed, overlay accuracy of a few nanometers or less may be required. However, when multiple scan fields SF or multiple semiconductor wafers are continuously exposed, temperature variations in the exposure apparatus 200 can cause misalignment of the exposure results, making it difficult to meet the required overlay accuracy.

[0046] For example, the reticle placed on the reticle stage RT may absorb part of the pulsed laser light, causing the reticle's temperature to rise. The reticle pattern drawn on the reticle is not uniform across its surface, and the number of times the pulsed laser light is multiply reflected on both sides of the reticle varies depending on the pattern density, causing temperature variations across the reticle surface and uneven expansion of the reticle. As a result, positional deviations in the exposure result occur depending on the time elapsed since the start of exposure and the position on the reticle surface.

[0047] Furthermore, optical elements included in the projection optical system 202 may absorb part of the pulsed laser light, causing a rise in temperature of the optical elements. Diffracted light according to the settings of the illumination optical system 201 and the reticle pattern is incident on the projection optical system 202, and because the diffracted light passes through specific parts of the projection optical system 202, temperature variations occur in the projection optical system 202, causing non-uniform expansion and local changes in the refractive index. As a result, the paths of the light rays passing through the projection optical system 202 change, causing complex aberrations. Depending on the time elapsed since the start of exposure and the position within the beam cross section B, the imaging position may shift in the optical axis direction, changing the critical dimension (CD), or the imaging position may shift in a direction perpendicular to the optical axis, causing a positional deviation in the exposure result.

[0048] Some of the embodiments described below relate to suppressing variations in positional deviation and CD that vary with time elapsed since the start of exposure and also vary with position within the scan field SF.

[0049] 6 shows a schematic configuration of an exposure system according to the first embodiment. In addition to a laser apparatus 100 and an exposure apparatus 200, the exposure system includes a lithography control processor 310 and a wafer inspection system 700. The wafer inspection system 700 includes an inspection apparatus 701 and a wafer inspection processor 710.

[0050] The lithography control processor 310 is a processing device including a memory 312 in which a control program is stored and a CPU 311 that executes the control program. The lithography control processor 310 is specially configured or programmed to execute various processes included in the present disclosure. The lithography control processor 310 is connected to each of the laser control processor 130, the exposure control processor 210, and the wafer inspection processor 710, and transmits and receives various data and various signals to and from these processors. The lithography control processor 310 may be connected to multiple laser control processors 130 included in multiple laser apparatuses 100, multiple exposure control processors 210 included in multiple exposure apparatuses 200, or multiple wafer inspection processors 710 included in multiple wafer inspection systems 700 installed in a semiconductor factory.

[0051] The inspection device 701 is, for example, a device that irradiates a semiconductor wafer (not shown) placed on a workpiece table WT with laser light and detects the reflected or diffracted light to measure the CD or overlay error of a fine pattern formed on the semiconductor wafer. Alternatively, the inspection device 701 may be a device that includes a high-resolution scanning electron microscope (SEM) and captures an image of the semiconductor wafer to measure the CD of the fine pattern.

[0052] The wafer inspection processor 710 is a processing device that includes a memory 712 that stores a control program and a CPU 711 that executes the control program. The wafer inspection processor 710 is specially configured or programmed to execute various processes included in this disclosure. The wafer inspection processor 710 is connected to both the inspection tool 701 and the lithography control processor 310, and transmits and receives various data and signals between the inspection tool 701 and the lithography control processor 310.

[0053] 2.2 Operation 2.2.1 Wavefront Aberration W We will now explain wavefront aberration W, which is one way of expressing aberration. The projection optical system 202 is designed to convert a spherical wave emanating from a point on the reticle into an ideal spherical wave that converges at a point on the semiconductor wafer. However, if for some reason the conversion to an ideal spherical wave is not possible, the light may not converge at a single point, or may converge at a point but at a different location than where it should have. Wavefront aberration W is an expression of this aberration as a deviation from the ideal spherical surface.

[0054] As shown in the following equation, the wavefront aberration W is expressed as a function of the Zernike function series Z ｎ It can be expressed as a linear combination of W = Σ ｎ (a ｎ Z ｎ ) = a １ Z １ +a ２ Z ２ +a ３ Z ３ +...

[0055] Here, a ｎ is a weighting coefficient for specifying the wavefront aberration W. The subscript n is a natural number from 1 to infinity, and is used to define the Zernike function series Z ｎ is an infinite series of functions. ｎ Z ｎ are called Zernike terms. In practice, the first 36, 49, 81, or 121 Zernike terms a ｎ Z ｎ is often used. ｎ Z ｎ By using this, it is possible to express complex aberrations such as, for example, a part of the image being shifted in the direction of the optical axis or in a direction perpendicular to the optical axis.

[0056] In the following description, the weighting coefficient a ｎ The display of Zernike term a ｎ Z ｎ Simply Z ｎ It is written as follows.

[0057] 7 is a flowchart showing the wavelength correction process according to the first embodiment. The lithography control processor 310 calculates the wavelength correction amount Δλ based on the exposure result of the pre-exposure and information on the exposure apparatus 200 and the reticle pattern through the following process. ｉｊｋ is determined and the actual exposure is performed.

[0058] In S100, the lithography control processor 310 sends a signal to the exposure control processor 210 and the laser control processor 130 to perform pre-exposure without wavelength correction. The pre-exposure is performed using the same exposure sequence as the exposure sequence for the actual exposure to manufacture an electronic device. In order to distinguish the semiconductor wafer to be pre-exposed from the semiconductor wafer to be actual exposure, it will be referred to as a pre-exposed wafer hereinafter.

[0059] In S200, the lithography control processor 310 calculates the overlay error D of the pre-exposed wafer. ｉｊｋｐｇ A signal is sent to the wafer inspection processor 710 to measure the overlay error D ｉｊｋｐｇ is an example of a measurement result regarding the positional deviation of the exposure result. ｉｊｋｐｇ Alternatively, the CD may be measured.

[0060] Overlay error D ｉｊｋｐｇ It is not necessary to measure the overlay error D for all pre-exposed wafers, but it is sufficient to measure it for one or more pre-exposed wafers. ｉｊｋｐｇ It is not necessary to measure all scan fields SF included in the pre-exposure wafer, but it is sufficient to measure two or more scan fields SF.

[0061] 8 shows the entire pre-exposure wafer WF or semiconductor wafer WF and some details thereof. Pre-exposure includes exposure of multiple pre-exposure wafers WF, and main exposure includes exposure of multiple semiconductor wafers WF. The subscript i is used to identify one of the multiple pre-exposure wafers WF or one of the multiple semiconductor wafers WF. The subscript i indicates the number of the pre-exposure wafer WF exposed from the start of pre-exposure or the number of the semiconductor wafer WF exposed from the start of main exposure. When referring to the first and second pre-exposure wafers WF, the order of exposure of the first and second pre-exposure wafers WF is indicated by an ordinal number, and when referring to the first and second semiconductor wafers WF, the order of exposure of the first and second semiconductor wafers WF is indicated by an ordinal number.

[0062] One pre-exposure wafer WF or one semiconductor wafer WF includes multiple scan fields SF. The subscript j identifies one of the multiple scan fields SF. The subscript j indicates the scan field SF that is scanned in one pre-exposure wafer WF or one semiconductor wafer WF. The first and second scan fields in this disclosure are scan fields SF included in the first semiconductor wafer WF. The third and fourth scan fields in this disclosure are scan fields SF included in the first pre-exposure wafer WF that have an overlay error D ｉｊｋｐｇ The fifth scan field in the present disclosure is a scan field SF included in the second pre-exposure wafer WF, and is a scan field SF in which the overlay error D ｉｊｋｐｇ is the scan field SF where measurement is performed. The sixth and seventh scan fields in the present disclosure are scan fields SF included in the second semiconductor wafer WF.

[0063] In one scan field SF, a position on the Y axis parallel to the scanning direction is defined as an intra-field position, and the subscript specifying one intra-field position is k. The number of intra-field positions included in one scan field SF corresponds to the number of models described below.

[0064] A position within the beam cross section B (see FIGS. 3 to 5) of the pulsed laser light at the position of the workpiece table WT is defined as an intra-slit position, and a subscript specifying one intra-slit position is denoted by p.

[0065] The measurement points for positional deviation included in the reticle pattern are called gauges, and some examples of gauges are shown by double-headed arrows in Figure 8. A subscript g is used to identify one gauge.

[0066] i, j, k, p, and g are natural numbers. ｉｊｋｐｇ is measured for multiple scan fields SF, multiple in-field positions, multiple in-slit positions, and multiple gauges. ｉｊｋｐｇ is a measurement value in which the pre-exposed wafer WF, scan field SF, in-field position, in-slit position, and gauge to be measured are specified by the subscripts i, j, k, p, and g.

[0067] Referring again to FIG. 7, in S300, the lithography control processor 310 calculates the change dZ of the wavefront aberration W with respect to the change in wavelength. ｎｐ The details of S300 will be described later with reference to FIG. ｎｐ / dλ corresponds to the first change amount in this disclosure.

[0068] In S400, the lithography control processor 310 calculates the amount of change in positional deviation ∂E with respect to the change in wavefront aberration W. ｇ / ∂Z ｎ The details of S400 will be described later with reference to FIG. 10. The processes of S300 and S400 may be executed before S100. The change amount ∂E ｇ / ∂Z ｎ corresponds to the second change amount in this disclosure.

[0069] In S500, the lithography control processor 310 calculates the measured overlay error D ｉｊｋｐｇ The wavelength correction amount Δλ corresponding to ｉｊｋ The details of S500 will be described later with reference to FIG.

[0070] In S600, the lithography control processor 310 calculates the measured overlay error D ｉｊｋｐｇ The wavelength correction amount Δλ corresponding to ｉｊｋ From this, the wavelength correction amount Δλ ｉｊｋ A model is created, and the wavelength correction amount Δλ of all semiconductor wafers WF is calculated from the model. ｉｊｋ The details of S600 will be described later with reference to FIGS.

[0071] In S800, the lithography control processor 310 calculates the determined wavelength correction amount Δλ. ｉｊｋ The wavelength is corrected based on the wavelength of the laser beam, and a signal is sent to the exposure control processor 210 and the laser control processor 130 so that the actual exposure of the semiconductor wafer WF is performed. ｉｊｋｐｇ may be cancelled.

[0072] After S800, the lithography control processor 310 ends the processing of this flowchart.

[0073] 2.2.3 dZ ｎｐ 9 shows the change in wavefront aberration W with respect to the change in wavelength, dZ ｎｐ 9 is a flowchart showing details of the process for calculating / dλ. The process shown in Fig. 9 corresponds to the subroutine of S300 in Fig. 7.

[0074] In S301, the lithography control processor 310 inputs design data of the projection optical system 202 into software capable of ray tracing. Examples of software capable of ray tracing include optical system design and evaluation software such as Zemax by Ansys Inc. and CODE V by Synopsys Inc.

[0075] In S302, the lithography control processor 310 performs ray tracing at all positions within the slit in the beam cross section B while changing the wavelength on the software.

[0076] In S303, the lithography control processor 310 converts the ray tracing results into wavefront aberration W and calculates the Zernike term Z for changes in wavelength λ. ｎｐ The change in dZ ｎｐ / dλ. Amount of change dZ ｎｐ Since / dλ depends on the position in the slit, the Zernike term Z ｎ is given the subscript p.

[0077] After S303, the lithography control processor 310 ends the processing of this flowchart and returns to the processing shown in FIG.

[0078] 2.2.4 ∂E ｇ / ∂Z ｎ FIG. 10 shows the change in positional deviation ∂E with respect to the change in wavefront aberration W. ｇ / ∂Z ｎ 10 is a flowchart showing the details of the process for calculating the .times. ...

[0079] In S401, the lithography control processor 310 inputs design data of the reticle pattern and setting parameters of the exposure apparatus 200 into lithography simulation software. Examples of lithography simulation software include Prolith by KLA, S-litho by Synopsys, and Hyperlith by Panoramic Technology.

[0080] In S402, the lithography control processor 310 calculates the Zernike term Z ｎ The amount of change in positional deviation ∂E ｇ / ∂Z ｎ is calculated for all gauges of the reticle pattern. ｇ / ∂Z ｎ is expressed as a partial derivative because the position error E ｇ is a multiple Zernike term Z ｎ This is because it is affected by

[0081] After S402, the lithography control processor 310 ends the processing of this flowchart and returns to the processing shown in FIG.

[0082] 2.2.5 Measured overlay error D ｉｊｋｐｇ The wavelength correction amount Δλ corresponding to ｉｊｋCalculation of the measured overlay error D ｉｊｋｐｇ The wavelength correction amount Δλ corresponding to ｉｊｋ 11 is a flowchart showing the details of the process for calculating the .times. ...

[0083] In S501, S502, and S503, the lithography control processor 310 sets counters i, j, and k, which identify the pre-exposure wafer WF, the scan field SF, and the position within the field, to 1, respectively. The counters i, j, and k correspond to the subscripts described above.

[0084] In S504, the lithography control processor 310 calculates the wavelength correction amount Δλ that satisfies the following equation and minimizes the left side of the equation: ｉｊｋ Ask for.

[0085] The right side of the above equation is the measured overlay error D ｉｊｋｐｇ The left side is the sum of the absolute values ​​of the wavelength-corrected overlay error for all positions in the slit and all gauges. To explain the left side in more detail, (∂E ｇ / ∂Z ｎ ) (dZ ｎｐ / dλ)Δλ ｉｊｋ is the wavelength Δλ ｉｊｋ This value is calculated for each Zernike term, each position in the slit, and each gauge. This value is integrated for all Zernike terms to obtain the measured overlay error D ｉｊｋｐｇ The left side of the equation corresponds to the sum of the absolute values ​​of all the positions in the slit and all the gauges.

[0086] In S505, the lithography control processor 310 calculates the wavelength correction amount Δλ for all intra-field positions. ｉｊｋ It is determined whether the calculation of the wavelength correction amount Δλ has been completed. ｉｊｋIf there is a position in the field for which the wavelength correction amount Δλ has not been calculated (S505: NO), the lithography control processor 310 proceeds to S506. ｉｊｋ If calculated (S505: YES), the lithography control processor 310 advances the process to S507.

[0087] In S506, the lithography control processor 310 adds 1 to the counter k that specifies the intra-field position, updates k, and returns the process to S504.

[0088] In S507, the lithography control processor 310 calculates the wavelength correction amount Δλ for all the measured scan fields SF. ｉｊｋ It is determined whether the calculation of the wavelength correction amount Δλ has been completed. ｉｊｋ If there is a scan field SF for which the wavelength correction amount Δλ has not been calculated (S507: NO), the lithography control processor 310 proceeds to S508. ｉｊｋ If calculated (S507: YES), the lithography control processor 310 advances the process to S509.

[0089] In S508, the lithography control processor 310 adds 1 to the counter j that identifies the scan field SF to update j, and returns the process to S503.

[0090] In S509, the lithography control processor 310 calculates the wavelength correction amount Δλ for all the measured pre-exposure wafers WF. ｉｊｋ It is determined whether the calculation of the wavelength correction amount Δλ has been completed. ｉｊｋ If there is a pre-exposure wafer WF for which the wavelength correction amount Δλ has not been calculated (S509: NO), the lithography control processor 310 proceeds to S510. ｉｊｋ If calculated (S509: YES), the lithography control processor 310 ends the processing of this flowchart and returns to the processing shown in FIG.

[0091] In S510, the lithography control processor 310 adds 1 to the counter i that identifies the pre-exposure wafer WF to update i, and returns the process to S502.

[0092] 2.2.6 Wavelength Correction Amount Δλ for All Semiconductor Wafers WF ｉｊｋ Calculation of the wavelength correction amount Δλ in S600 of FIG. 7 with reference to FIGS. 12 to 16. ｉｊｋ A model is created to calculate the wavelength correction amount Δλ for all semiconductor wafers WF. ｉｊｋ The process of calculating the following will be described.

[0093] 12 shows a method for converting the subscript i that identifies the semiconductor wafer WF and the subscript j that identifies the scan field SF into the elapsed time t from the start of exposure. The number of scan fields SF included in one semiconductor wafer WF is defined as jmax. As the value of the subscript j that identifies the scan field SF increases, the elapsed time t from the start of exposure increases. Every time 1 is added to the value of the subscript i that identifies the semiconductor wafer WF, the value of the subscript j is reset, and as the value of the subscript j increases, the elapsed time t from the start of exposure increases further. From this relationship, the subscripts i and j are converted into the elapsed time t using the following formula: t = (i - 1) × jmax + j

[0094] FIG. 13 shows the measured overlay error D ｉｊｋｐｇ The wavelength correction amount Δλ corresponding to ｉｊｋ The subscripts i and j in the above figures are converted into elapsed time t and plotted as the wavelength correction amount Δλk(t). The horizontal axis in Fig. 13 is elapsed time t. The small circles in Fig. 13 represent the wavelength correction amount Δλk(t).

[0095] FIG. 14 shows an example of a model obtained by fitting the wavelength correction amount Δλk(t) to an exponential function. It is believed that the change in positional deviation over time corresponds to the temperature rise of the reticle and optical elements after exposure begins, and that the temperature rise becomes more gradual as it approaches the saturation temperature. Therefore, the wavelength correction amount Δλk(t) is fitted to the following function: Δλk(t)=λmaxk(1-e －ｔ／τｋ )

[0096] Here, λmaxk is the maximum value of Δλk(t), and τk is the time constant. A model is created by deriving λmaxk and τk. λmaxk and τk can be derived by the least squares method. That is, the measured overlay error D ｉｊｋｐｇ The wavelength correction amount Δλ corresponding to ｉｊｋ The wavelength correction amount Δλk(t) is obtained by converting the subscripts i and j into the elapsed time t, and the right side of the above equation is λmaxk(1-e －ｔ／τｋ λmaxk and τk are derived so that the sum of the squares of the differences between

[0097] FIG. 15 shows examples of models created for each subscript k. Figure 15 shows models for k values ​​of 1, 2, and 3. The multiple models correspond to multiple different intra-field positions, and each model shows the relationship between the elapsed time t from the start of exposure and the wavelength correction amount Δλk(t). The reason for creating multiple models is that the reticle temperature differs depending on the intra-field position, requiring different wavelength correction amounts Δλk(t).

[0098] Fig. 16 shows an example of a change pattern in the wavelength of the pulsed laser beam scanning the scan field SF. The horizontal axis in Fig. 16 represents the Y-direction position of the scan field SF. Once the semiconductor wafer WF to be exposed and the scan field SF are identified, the elapsed time t can be identified from the corresponding subscripts i and j according to Fig. 12, and the change pattern in the wavelength of the pulsed laser beam can be obtained from the multiple models shown in Fig. 15.

[0099] For example, if the elapsed time corresponding to the first scan field of the first semiconductor wafer WF is t1, wavelength correction amounts Δλ1(t1), Δλ2(t1), Δλ3(t1), ... corresponding to the multiple in-field positions at the elapsed time t1 can be found from the multiple models in Fig. 15. By finding an approximation curve from the wavelength correction amounts Δλ1(t1), Δλ2(t1), Δλ3(t1), ... or by performing interpolation processing, the wavelength of the first pulsed laser beam scanning the first scan field can be set to a first pattern P1 that changes depending on the in-field position.

[0100] If the elapsed time corresponding to the second scan field of the first semiconductor wafer WF that is scanned after scanning the first scan field is t2, wavelength correction amounts Δλ1(t2), Δλ2(t2), Δλ3(t2), ... corresponding to the multiple in-field positions at the elapsed time t2 can be found from the multiple models in Fig. 15. From these wavelength correction amounts Δλ1(t2), Δλ2(t2), Δλ3(t2), ..., the wavelength of the second pulsed laser light that scans the second scan field can be set to a second pattern P2 that changes depending on the in-field position.

[0101] 2.2.7 Relationship between Wavelength Fluctuation Within Scan Field SF and Wavelength Fluctuation According to Elapsed Time t As can be seen from Figure 15 and the above-mentioned model equation, when the elapsed time t is 1, that is, when the first scan field SF of the first semiconductor wafer WF is exposed, the wavelength correction amount Δλk(t) is a value close to 0. The wavelength at that time is defined as the initial wavelength. As time passes after the start of exposure, the absolute value of the wavelength correction amount Δλk(t) increases, and therefore the absolute value of the difference between the initial wavelength and the subsequent wavelength also increases.

[0102] Therefore, when the difference between the initial wavelength and the average wavelength of the first pattern P1 is defined as the first average correction amount, and the difference between the initial wavelength and the average wavelength of the second pattern P2 is defined as the second average correction amount, the absolute value of the first average correction amount is smaller than the absolute value of the second average correction amount.

[0103] However, as can be seen from Figure 16, the wavelength fluctuation range in each of the first and second patterns P1 and P2 may be larger than the difference between the first and second average correction amounts. For example, when the second scan field is scanned after the first scan field, the difference between the first and second average correction amounts is small. In this case, when the maximum correction amount is the maximum absolute value of the difference between the initial wavelength and the wavelength of the first pattern P1 and the minimum absolute value of the difference between the initial wavelength and the wavelength of the second pattern P2, the maximum correction amount is larger than the minimum correction amount.

[0104] Similarly, when exposing multiple semiconductor wafers WF, the wavelength change pattern of the pulsed laser beam can be obtained from the multiple models shown in Fig. 15. For example, the wavelength of the third pulsed laser beam used to scan the sixth scan field of the second semiconductor wafer WF, which is exposed after the first semiconductor wafer WF has been exposed, can be set to a third pattern that is different from both the first and second patterns P1 and P2. Furthermore, the wavelength of the fourth pulsed laser beam used to scan the seventh scan field of the second semiconductor wafer WF can be set to a fourth pattern that is different from both the first and second patterns P1 and P2 and the third pattern.

[0105] In this case, when the difference between the initial wavelength and the average wavelength of the second pattern P2 is defined as the second average correction amount, and the difference between the initial wavelength and the average wavelength of the third pattern is defined as the third average correction amount, the absolute value of the second average correction amount is smaller than the absolute value of the third average correction amount.

[0106] However, the wavelength fluctuation range in each of the second pattern P2 and the third pattern P3 may be greater than the difference between the second and third average correction amounts. For example, when the sixth scan field is scanned after the second scan field, the difference between the second and third average correction amounts is small. In this case, when the maximum correction amount is the maximum absolute value of the difference between the initial wavelength and the wavelength of the second pattern P2, and the minimum absolute value of the difference between the initial wavelength and the wavelength of the third pattern P3 is the minimum correction amount, the maximum correction amount is greater than the minimum correction amount. Note that the magnitude relationship between the average correction amounts and the magnitude relationship between the maximum and minimum correction amounts described above are merely examples, and the calculation results may differ from these examples.

[0107] 2.3 Operation (1) According to the first embodiment, the exposure method includes the following first and second steps.

[0108] In the first step, based on measurement results regarding the positional deviation of the exposure result by pre-exposure using the exposure apparatus 200, the wavelength of the first pulsed laser light that scans the first scan field of the first semiconductor wafer WF is set to a first pattern P1 that changes depending on the position within the field along the scan direction in the first scan field, and the wavelength of the second pulsed laser light that scans the second scan field of the first semiconductor wafer WF is set to a second pattern P2 that changes depending on the position within the field along the scan direction in the second scan field and is different from the first pattern P1.

[0109] In the second step, the exposure device 200 is used to scan a first scan field with a first pulsed laser beam, and then scan a second scan field with a second pulsed laser beam.

[0110] This allows the exposure position deviation to be reduced by changing the wavelength for each scan field SF and for each position within the field to change the chromatic aberration, even if the reticle in the exposure apparatus 200 undergoes uneven thermal expansion, or even if the projection optical system 202 undergoes localized thermal expansion, or even if the thermal expansion changes over time t.

[0111] (2) According to the first embodiment, the first step includes setting the wavelengths of the first and second pulsed laser beams based on the positional shift of the exposure results at multiple intra-field positions of the third scan field of the first pre-exposed wafer WF on which pre-exposure has been performed, and the positional shift of the exposure results at multiple intra-field positions of the fourth scan field of the first pre-exposed wafer WF.

[0112] According to this, by using the measurement results of the positional deviation for each scan field SF and for each position within the field by pre-exposure, it is possible to set the wavelength so as to appropriately reduce the positional deviation of the exposure.

[0113] (3) According to the first embodiment, the first step is to calculate the first change amount dZ obtained based on information from the exposure apparatus 200 as the change amount of the wavefront aberration W with respect to the change in wavelength. ｎｐ / dλ, and a second change amount ∂E obtained based on information about the exposure apparatus 200 and information about the reticle pattern as a change amount of positional deviation with respect to a change in wavefront aberration W. ｇ / ∂Z ｎ Based on this, a wavelength correction amount Δλ according to the time difference between the pre-exposures of the third and fourth scan fields and the position within the field is calculated. ｉｊｋ The wavelength correction amount Δλ is calculated. ｉｊｋ and setting the wavelengths of the first and second pulsed laser beams based on the above.

[0114] According to this, by using the relationship between the change in wavelength and the change in positional deviation in addition to the measurement result of the positional deviation, it is possible to set the wavelength so as to appropriately reduce the positional deviation of the exposure.

[0115] (4) According to the first embodiment, the first step includes setting the wavelengths of the first and second pulsed laser beams based on the positional shift of the exposure results at multiple intra-field positions of the third scan field of the first pre-exposed wafer WF that has been pre-exposed, and the positional shift of the exposure results at multiple intra-field positions of the fifth scan field of the second pre-exposed wafer WF that has been pre-exposed after the first pre-exposed wafer WF.

[0116] According to this, by pre-exposing a plurality of pre-exposure wafers WF, the accuracy of wavelength correction can be improved.

[0117] (5) According to the first embodiment, the first step is to calculate the first change amount dZ obtained based on information from the exposure apparatus 200 as the change amount of the wavefront aberration W with respect to the change in wavelength. ｎｐ / dλ, and a second change amount ∂E obtained based on information about the exposure apparatus 200 and information about the reticle pattern as a change amount of positional deviation with respect to a change in wavefront aberration W. ｇ / ∂Z ｎ Based on this, a wavelength correction amount Δλ according to the time difference between the pre-exposures of the third and fifth scan fields and the position within the field is calculated. ｉｊｋ The wavelength correction amount Δλ is calculated. ｉｊｋ and setting the wavelengths of the first and second pulsed laser beams based on the above.

[0118] According to this, by using the relationship between the change in wavelength and the change in positional deviation in addition to the measurement result of the positional deviation, it is possible to set the wavelength so as to appropriately reduce the positional deviation of the exposure.

[0119] (6) According to the first embodiment, the first step is to generate a plurality of models corresponding to different positions in a field, each of which has a time t elapsed since the start of exposure and a wavelength correction amount Δλ. ｉｊｋ and setting the wavelengths of the first and second pulsed laser beams based on the plurality of models.

[0120] According to this, by creating a model, even if there are portions where the positional deviation of the exposure result has not been measured, the wavelength can be appropriately set to reduce the positional deviation of the exposure.

[0121] (7) According to the first embodiment, the elapsed time t is associated with the number of semiconductor wafers WF that the first semiconductor wafer WF is exposed to and the number of scan fields SF that the first and second scan fields are scanned in.

[0122] According to this, by converting the number of semiconductor wafers WF and the number of scan fields SF onto the time axis, the model can be expressed as a function of elapsed time t.

[0123] (8) According to the first embodiment, the first step calculates the positional deviations of the exposure results at positions within a plurality of fields of the third scan field of the first pre-exposed wafer WF on which pre-exposure has been performed, the positional deviations of the exposure results at positions within a plurality of fields of the fourth scan field of the first pre-exposed wafer WF, and the first change amount dZ obtained based on information from the exposure apparatus 200 as the amount of change in wavefront aberration W with respect to the change in wavelength. ｎｐ / dλ, and a second change amount ∂E obtained based on information about the exposure apparatus 200 and information about the reticle pattern as a change amount of positional deviation with respect to a change in wavefront aberration W. ｇ / ∂Z ｎ Based on this, a wavelength correction amount Δλ according to the time difference between the pre-exposures of the third and fourth scan fields and the position within the field is calculated. ｉｊｋ The wavelength correction amount Δλ is calculated.ｉｊｋ and setting the wavelengths of the first and second pulsed laser beams based on the plurality of models.

[0124] According to this, the wavelength correction amount Δλ according to the time difference of pre-exposure between different scan fields SF and the position within the field ｉｊｋ By creating multiple models from the above, it is possible to set the wavelength so as to appropriately reduce the exposure position deviation.

[0125] (9) According to the first embodiment, the first step calculates the positional deviation of the exposure result at a plurality of positions in the third scan field of the first pre-exposed wafer WF that has been pre-exposed, the positional deviation of the exposure result at a plurality of positions in the fifth scan field of the second pre-exposed wafer WF that has been pre-exposed after the first pre-exposed wafer WF, and the first change amount dZ obtained based on information from the exposure apparatus 200 as the amount of change in wavefront aberration W with respect to a change in wavelength. ｎｐ / dλ, and a second change amount ∂E obtained based on information about the exposure apparatus 200 and information about the reticle pattern as a change amount of positional deviation with respect to a change in wavefront aberration W. ｇ / ∂Z ｎ and based on the time difference between the pre-exposures of the first and second pre-exposure wafers WF and the wavelength correction amount Δλ according to the position within the field, ｉｊｋ The wavelength correction amount Δλ is calculated. ｉｊｋ and setting the wavelengths of the first and second pulsed laser beams based on the plurality of models.

[0126] According to this, the wavelength correction amount Δλ according to the time difference of pre-exposure of different pre-exposed wafers WF and the position in the field ｉｊｋ By creating multiple models from the above, it is possible to set the wavelength so as to appropriately reduce the exposure position deviation.

[0127] (10) According to the first embodiment, the first step is to calculate a wavelength correction amount Δλ corresponding to the first scan field. ｉｊｋ from each of the plurality of models, the wavelength of the first pulsed laser beam is set to the first pattern P1, and the wavelength correction amount Δλ corresponding to the second scan field is calculated.ｉｊｋ from each of the plurality of models, and thereby setting the wavelength of the second pulsed laser beam to the second pattern P2.

[0128] According to this, by using a plurality of models respectively corresponding to a plurality of different positions in the field, it is possible to set a wavelength pattern that changes depending on the position in the field.

[0129] (11) According to the first embodiment, the pre-exposure includes exposing the pre-exposed wafer WF to a certain wavelength.

[0130] This makes it possible to keep the influence of wavelength constant and obtain appropriate measurement results.

[0131] (12) According to the first embodiment, the absolute value of the first average correction amount, which is the difference between the initial wavelength, which is the wavelength of the first pulsed laser light irradiated to the first semiconductor wafer WF, and the average value of the wavelength of the first pattern P1, is smaller than the absolute value of the second average correction amount, which is the difference between the initial wavelength and the average value of the wavelength of the second pattern P2.

[0132] This allows the average correction amount to be increased in accordance with the temperature rise when exposing a plurality of scan fields SF.

[0133] (13) According to the first embodiment, the maximum correction amount, which is the maximum value of the absolute value of the difference between the initial wavelength and the wavelength of the first pattern P1, is greater than the minimum correction amount, which is the minimum value of the absolute value of the difference between the initial wavelength and the wavelength of the second pattern P2, and the second step scans the second scan field after the first scan field.

[0134] This allows wavelength correction to be performed appropriately for each position within the field by making the amount of wavelength change within the scan field SF larger than the amount of wavelength change when moving from one scan field SF to the next scan field SF.

[0135] (14) According to the first embodiment, the first step includes changing the wavelength of the third pulsed laser beam used to scan a sixth scan field of the second semiconductor wafer WF, which is exposed after the first semiconductor wafer WF is exposed, depending on the position within the field along the scan direction in the sixth scan field, and setting the wavelength to a third pattern different from either the first or second patterns P1 or P2, and changing the wavelength of the fourth pulsed laser beam used to scan a seventh scan field of the second semiconductor wafer WF depending on the position within the field along the scan direction in the seventh scan field, and setting the wavelength to a fourth pattern different from either the first to third patterns. The second step includes scanning the sixth scan field with the third pulsed laser beam using the exposure apparatus 200, and then scanning the seventh scan field with the fourth pulsed laser beam. The absolute value of the second average correction amount, which is the difference between the initial wavelength, which is the wavelength of the first pulsed laser light irradiated onto the first semiconductor wafer WF, and the average value of the wavelength of the second pattern P2, is smaller than the absolute value of the third average correction amount, which is the difference between the initial wavelength and the average value of the wavelength of the third pattern.

[0136] This allows the average correction amount to be increased in accordance with the temperature rise when a plurality of semiconductor wafers WF are exposed.

[0137] (15) According to the first embodiment, the maximum correction amount, which is the maximum value among the absolute values ​​of the difference between the initial wavelength and the wavelength of the second pattern P2, is greater than the minimum correction amount, which is the minimum value among the absolute values ​​of the difference between the initial wavelength and the wavelength of the third pattern, and the second step scans the sixth scan field after the second scan field.

[0138] This allows wavelength correction to be performed appropriately for each position within the field by making the amount of wavelength change within the scan field SF larger than the amount of wavelength change when moving from one semiconductor wafer WF to the next semiconductor wafer WF.

[0139] Since the wavelength correction in this embodiment is based on the measurement results when a specific reticle pattern is used for exposure, when a new reticle pattern is used for exposure, the measurement results for the new reticle pattern can be acquired and the wavelength correction pattern can be reset. However, even when the reticle is replaced, if the reticle pattern does not change, it is not necessary to reset the wavelength correction pattern. Also, even when the exposure tool 200 is replaced, it is not necessary to reset the wavelength correction pattern if the model number and settings of the exposure tool 200 do not change.

[0140] In other respects, the first embodiment is similar to the comparative example.

[0141] 3. Overlay error D ｉｊｋｐｇ 17 is a flowchart showing the wavelength correction process according to the second embodiment. In the second embodiment, the processes of S600a and S700a are performed instead of S500 and S600 in FIG. 7. The processes of S300 and S400 may be performed between S600a and S700a.

[0142] In S600a, the lithography control processor 310 calculates the measured overlay error D ｉｊｋｐｇ From the overlay error D ｉｊｋｐｇ A model of the overlay error D of all semiconductor wafers WF is created from the model. ｉｊｋｐｇ The details of step S600a will be described later with reference to FIGS.

[0143] In S700a, the lithography control processor 310 calculates the wavelength correction amount Δλ for all semiconductor wafers WF. ｉｊｋ The details of step S700a will be described later with reference to FIGS.

[0144] 3.1.2 Overlay error D of all semiconductor wafers WF ｉｊｋｐｇ 18 to 20, the overlay error D ｉｊｋｐｇ A model of the overlay error D of all semiconductor wafers WF is created. ｉｊｋｐｇThe process of determining this will be described.

[0145] FIG. 18 shows a method for converting the subscript i that identifies the semiconductor wafer WF and the subscript j that identifies the scan field SF into the elapsed time t from the start of exposure, and the content thereof is the same as that of FIG.

[0146] FIG. 19 shows the measured overlay error D ｉｊｋｐｇ The subscripts i and j in the above equation are converted into elapsed time t and plotted as the overlay error Dkpg(t). The horizontal axis in Fig. 19 represents elapsed time t. The small circles in Fig. 19 represent the measured overlay error Dkpg(t).

[0147] FIG. 20 shows an example of a model obtained by fitting the registration error Dkpg(t) to the following exponential function: Dkpg(t)=Dmaxkpg(1−e －ｔ／τｋｐｇ )

[0148] Here, Dmaxkpg is the maximum value of Dkpg(t), and τkpg is the time constant. A model is created by deriving Dmaxkpg and τkpg. Dmaxkpg and τkpg can be derived by the least squares method. That is, the measured overlay error D ｉｊｋｐｇ The overlay error Dkpg(t) is obtained by converting the subscripts i and j into the elapsed time t, and the right-hand side of the above equation is Dmaxkpg(1-e －ｔ／τｋｐｇ Dmaxkpg and τkpg are derived so that the sum of the squares of the differences between

[0149] In the first embodiment, the number of models of the wavelength correction amount Δλk(t) was the number of in-field positions included in one scan field SF, whereas in the second embodiment, a larger number of models of the overlay error Dkpg(t) are required. The number of models of the overlay error Dkpg(t) is, for example, the product of the number of in-field positions, the number of measured in-slit positions, and the number of measured gauges. The multiple models correspond to combinations of in-field positions, in-slit positions, and gauges selected from a plurality of mutually different in-field positions, a plurality of in-slit positions, and a plurality of gauges, and each model represents the relationship between the elapsed time t from the start of exposure and the overlay error Dkpg(t).

[0150] 3.1.3 Wavelength correction amount Δλ for all semiconductor wafers WF ｉｊｋ FIG. 21 shows the wavelength correction amount Δλ of all semiconductor wafers WF. ｉｊｋ 21 is a flowchart showing details of the process for calculating the value of the sigma sigma sigma. The process shown in FIG. 21 corresponds to the subroutine of S700a in FIG.

[0151] The processes of S701, S702, S703, S704, S705, S706, S708, and S710 are the same as S501, S502, S503, S504, S505, S506, S508, and S510 in FIG. 11, respectively. However, the overlay error D ｉｊｋｐｇ is the overlay error D measured in S200 ｉｊｋｐｇ Instead, the overlay error D determined from the model in S600a ｉｊｋｐｇ Therefore, in S704, the measured overlay error D ｉｊｋｐｇ The wavelength correction amount Δλ corresponding to ｉｊｋ In addition, the wavelength correction amount Δλ of all scan fields SF of all semiconductor wafers WF ｉｊｋ S704 is executed more times than S504.

[0152] In FIG. 21, the processes of S707a and S709a are performed instead of S507 and S509 in FIG.

[0153] In S707a, the lithography control processor 310 calculates the wavelength correction amount Δλ for all scan fields SF. ｉｊｋ It is determined whether the calculation of the wavelength correction amount Δλ has been completed. ｉｊｋ If there is a scan field SF for which the wavelength correction amount Δλ has not been calculated (S707a: NO), the lithography control processor 310 proceeds to S708. ｉｊｋ If calculated (S707a: YES), the lithography control processor 310 proceeds to S709a.

[0154] In S709a, the lithography control processor 310 calculates the wavelength correction amount Δλ for all semiconductor wafers WF. ｉｊｋ It is determined whether the calculation of the wavelength correction amount Δλ has been completed. ｉｊｋ If there is a semiconductor wafer WF for which the wavelength correction amount Δλ has not been calculated (S709a: NO), the lithography control processor 310 proceeds to S710. ｉｊｋ If calculated (S709a: YES), the lithography control processor 310 ends the processing of this flowchart and returns to the processing shown in FIG.

[0155] FIG. 22 shows the wavelength correction amount Δλ obtained in S704. ｉｊｋ The wavelength correction amount Δλ calculated in S704 is shown below. ｉｊｋ is an individual value determined for each semiconductor wafer WF, each scan field SF, and each position within the field, and is not a function of elapsed time t. However, for convenience of explanation, the subscripts i and j are converted to elapsed time t and expressed as Δλ(t).

[0156] 23 shows an example of a change pattern of the wavelength of the pulsed laser beam that scans the scan field SF. The horizontal axis of FIG. 23 represents the Y-direction position of the scan field SF.

[0157] For example, if the elapsed time corresponding to the first scan field is t1, wavelength correction amounts Δλ1(t1), Δλ2(t1), Δλ3(t1), ... corresponding to multiple intra-field positions at the elapsed time t1 can be found from the wavelength correction amount Δλk(t) shown in Fig. 22. By finding an approximation curve from the wavelength correction amounts Δλ1(t1), Δλ2(t1), Δλ3(t1), ... or by performing interpolation processing, the wavelength of the first pulsed laser beam that scans the first scan field can be set to the first pattern P1.

[0158] Similarly, if the elapsed time corresponding to the second scan field is t2, the wavelength correction amounts Δλ1(t2), Δλ2(t2), Δλ3(t2), ... corresponding to multiple intra-field positions at the elapsed time t2 can be obtained from the wavelength correction amount Δλk(t) shown in Figure 22, and the wavelength of the second pulsed laser light scanning the second scan field can be set to the second pattern P2.

[0159] 3.2 Operation (16) According to the second embodiment, the first step includes creating a plurality of models corresponding to a plurality of different in-field positions, each model indicating the relationship between the elapsed time t from the start of exposure and the positional deviation resulting from exposure, and setting the wavelengths of the first and second pulsed laser beams based on the plurality of models.

[0160] According to this, by creating a model, even if there are portions where the positional deviation of the exposure result has not been measured, the positional deviation of the exposure result can be reduced by appropriately calculating the positional deviation of the exposure result and correcting the wavelength.

[0161] (17) According to the second embodiment, the first step is to calculate the positional deviation obtained from each of the plurality of models corresponding to the first and second scan fields, and the first change amount dZ obtained based on information from the exposure apparatus 200 as the change amount of the wavefront aberration W with respect to the change in wavelength. ｎｐ / dλ, and a second change amount ∂E obtained based on information about the exposure apparatus 200 and information about the reticle pattern as a change amount of positional deviation with respect to a change in wavefront aberration W. ｇ / ∂Z ｎ and setting the wavelengths of the first and second pulsed laser beams based on the above.

[0162] According to this, by using the relationship between the change in wavelength and the change in positional deviation in addition to the positional deviation obtained from the model, the wavelength correction amount Δλ for appropriately reducing the positional deviation of exposure can be calculated. ｉｊｋ can be obtained.

[0163] (18) According to the second embodiment, the first step includes creating multiple models based on the misalignment of the exposure results at multiple in-field positions of the third scan field of the first pre-exposed wafer WF on which pre-exposure has been performed, and the misalignment of the exposure results at multiple in-field positions of the fourth scan field of the first pre-exposed wafer WF.

[0164] According to this, by obtaining measurement data of the positional deviation for each scan field SF and for each position within the field, it is possible to create an appropriate model that shows the relationship between the time t elapsed from the start of exposure and the positional deviation resulting from exposure.

[0165] (19) According to the second embodiment, the first step includes creating multiple models based on the misalignment of the exposure results at multiple in-field positions of the third scan field of the first pre-exposed wafer WF that has been pre-exposed, and the misalignment of the exposure results at multiple in-field positions of the fifth scan field of the second pre-exposed wafer WF that has been pre-exposed after the first pre-exposed wafer WF.

[0166] According to this, by pre-exposing a plurality of pre-exposed wafers WF and obtaining measurement data of misalignment, the accuracy of the model can be improved.

[0167] In other respects, the second embodiment is similar to the first embodiment.

[0168] 4. Other The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. It will also be apparent to those skilled in the art that the embodiments of the present disclosure can be used in combination.

[0169] Terms used throughout this specification and claims should be construed as "open ended" unless expressly stated otherwise. For example, terms such as "comprise," "have," "comprise," and "equip" should be construed as meaning "without excluding the presence of elements other than those listed." In addition, the modifier "a" should be construed as meaning "at least one" or "one or more." In addition, the term "at least one of A, B, and C" should be construed as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C," and should also be construed as including combinations other than "A," "B," and "C."

Claims

1. An exposure method comprising: a first step of setting a wavelength of a first pulsed laser light for scanning a first scan field of a first semiconductor wafer to a first pattern that varies depending on a position in the field along a scan direction in the first scan field, and setting a wavelength of a second pulsed laser light for scanning a second scan field of the first semiconductor wafer to a second pattern different from the first pattern, the second pattern being varied depending on a position in the field along the scan direction in the second scan field; and a second step of scanning the first scan field with the first pulsed laser light using the exposure device, and then scanning the second scan field with the second pulsed laser light.

2. An exposure method as described in claim 1, wherein the first step includes setting the wavelengths of the first and second pulsed laser beams based on: a positional shift of the exposure result at multiple in-field positions of a third scan field of a first pre-exposed wafer on which the pre-exposure has been performed; and a positional shift of the exposure result at multiple in-field positions of a fourth scan field of the first pre-exposed wafer.

3. An exposure method as defined in claim 2, wherein the first step further includes determining a wavelength correction amount corresponding to the time difference between the pre-exposures of the third and fourth scan fields and the position within the field based on a first change amount obtained based on information about the exposure apparatus as the change amount of wavefront aberration relative to the change in wavelength, and a second change amount obtained based on information about the exposure apparatus and information about a reticle pattern as the change amount of positional deviation relative to the change in wavefront aberration, and setting the wavelengths of the first and second pulsed laser beams based on the wavelength correction amount.

4. An exposure method as described in claim 1, wherein the first step includes setting the wavelengths of the first and second pulsed laser beams based on: a positional shift of the exposure result at multiple in-field positions of a third scan field of a first pre-exposed wafer on which the pre-exposure was performed; and a positional shift of the exposure result at multiple in-field positions of a fifth scan field of a second pre-exposed wafer on which the pre-exposure was performed after the first pre-exposed wafer.

5. An exposure method as defined in claim 4, wherein the first step further includes determining a wavelength correction amount corresponding to the time difference and intra-field position of the pre-exposure of the third and fifth scan fields based on a first change amount obtained based on information about the exposure apparatus as the change amount of wavefront aberration relative to a change in wavelength, and a second change amount obtained based on information about the exposure apparatus and information about a reticle pattern as the change amount of positional deviation relative to a change in wavefront aberration, and setting the wavelengths of the first and second pulsed laser beams based on the wavelength correction amount.

6. An exposure method as claimed in claim 1, wherein the first step includes creating a plurality of models corresponding to a plurality of mutually different in-field positions, each of the models indicating the relationship between the elapsed time from the start of exposure and the amount of wavelength correction, and setting the wavelengths of the first and second pulsed laser beams based on the plurality of models.

7. An exposure method according to claim 6, wherein the elapsed time is associated with the number of semiconductor wafers to be exposed of the first semiconductor wafer, and the number of scan fields to be scanned of the first and second scan fields.

8. An exposure method as described in claim 6, wherein the first step includes: determining the wavelength correction amount according to the time difference and intra-field position of the pre-exposure of the third and fourth scan fields based on: a positional shift of the exposure result at multiple intra-field positions of a third scan field of a first pre-exposed wafer on which the pre-exposure has been performed; a positional shift of the exposure result at multiple intra-field positions of a fourth scan field of the first pre-exposed wafer; a first change amount obtained based on information about the exposure apparatus as the amount of change in wavefront aberration relative to a change in wavelength; and a second change amount obtained based on information about the exposure apparatus and information about a reticle pattern as the amount of change in positional shift relative to a change in wavefront aberration, creating the multiple models based on the wavelength correction amount; and setting the wavelengths of the first and second pulsed laser beams based on the multiple models.

9. An exposure method as recited in claim 6, wherein the first step includes determining the wavelength correction amount according to the time difference and intra-field position of the pre-exposure of the first and second pre-exposed wafers based on: a positional shift of the exposure result at multiple intra-field positions of a third scan field of a first pre-exposed wafer on which the pre-exposure has been performed; a positional shift of the exposure result at multiple intra-field positions of a fifth scan field of a second pre-exposed wafer on which the pre-exposure has been performed after the first pre-exposed wafer; a first change amount obtained based on information about the exposure apparatus as a change in wavefront aberration relative to a change in wavelength; and a second change amount obtained based on information about the exposure apparatus and information about a reticle pattern as a change in positional shift relative to a change in wavefront aberration, creating the multiple models based on the wavelength correction amount, and setting the wavelengths of the first and second pulsed laser beams based on the multiple models.

10. An exposure method as described in claim 6, wherein the first step includes: setting the wavelength of the first pulse laser light in the first pattern by determining the wavelength correction amount corresponding to the first scan field from each of the multiple models; and setting the wavelength of the second pulse laser light in the second pattern by determining the wavelength correction amount corresponding to the second scan field from each of the multiple models.

11. The exposure method of claim 1, wherein said pre-exposure comprises exposing a pre-exposed wafer to a constant wavelength.

12. An exposure method as described in claim 1, wherein the absolute value of a first average correction amount, which is the difference between an initial wavelength, which is the wavelength of the first pulsed laser light irradiated to the first semiconductor wafer, and the average wavelength of the first pattern, is smaller than the absolute value of a second average correction amount, which is the difference between the initial wavelength and the average wavelength of the second pattern.

13. An exposure method as described in claim 12, wherein a maximum correction amount, which is the maximum value among the absolute values ​​of the difference between the initial wavelength and the wavelength of the first pattern, is greater than a minimum correction amount, which is the minimum value among the absolute values ​​of the difference between the initial wavelength and the wavelength of the second pattern, and the second step scans the second scan field subsequent to the first scan field.

14. An exposure method according to claim 1, wherein the first step further comprises: changing the wavelength of a third pulsed laser light for scanning a sixth scan field of a second semiconductor wafer exposed after exposing the first semiconductor wafer, depending on the position in the field along the scan direction in the sixth scan field, and setting the wavelength of a fourth pulsed laser light for scanning a seventh scan field of the second semiconductor wafer, depending on the position in the field along the scan direction in the seventh scan field, and setting the wavelength of a fourth pulsed laser light for scanning a seventh scan field of the second semiconductor wafer, depending on the position in the field along the scan direction in the seventh scan field, and setting the wavelength of a fourth pattern different from any of the first to third patterns; and the second step further comprises scanning the sixth scan field with the third pulsed laser light using the exposure device, and then scanning the seventh scan field with the fourth pulsed laser light; and an absolute value of a second average correction amount which is the difference between an initial wavelength, which is the wavelength of the initial pulsed laser light irradiated to the first semiconductor wafer, and an average value of the wavelengths of the second pattern is smaller than an absolute value of a third average correction amount which is the difference between the initial wavelength and the average value of the wavelengths of the third pattern. Exposure method.

15. An exposure method as described in claim 14, wherein a maximum correction amount, which is the maximum value among the absolute values ​​of the difference between the initial wavelength and the wavelength of the second pattern, is greater than a minimum correction amount, which is the minimum value among the absolute values ​​of the difference between the initial wavelength and the wavelength of the third pattern, and the second step scans the sixth scan field after the second scan field.

16. An exposure method as defined in claim 1, wherein the first step includes creating a plurality of models corresponding to a plurality of mutually different in-field positions, each of the models indicating the relationship between the elapsed time from the start of exposure and the positional deviation of the exposure result, and setting the wavelengths of the first and second pulsed laser beams based on the plurality of models.

17. An exposure method as described in claim 16, wherein the first step includes setting the wavelengths of the first and second pulsed laser beams based on: a positional shift determined from each of the plurality of models corresponding to the first and second scan fields; a first amount of change obtained based on information about the exposure apparatus as the amount of change in wavefront aberration relative to a change in wavelength; and a second amount of change obtained based on information about the exposure apparatus and information about a reticle pattern as the amount of change in positional shift relative to a change in wavefront aberration.

18. An exposure method as described in claim 16, wherein the first step includes creating the multiple models based on: a misalignment of the exposure results at multiple in-field positions of a third scan field of a first pre-exposed wafer on which the pre-exposure was performed; and a misalignment of the exposure results at multiple in-field positions of a fourth scan field of the first pre-exposed wafer.

19. An exposure method as described in claim 16, wherein the first step includes creating the multiple models based on: a misalignment of the exposure results at multiple in-field positions of a third scan field of a first pre-exposed wafer on which the pre-exposure was performed; and a misalignment of the exposure results at multiple in-field positions of a fifth scan field of a second pre-exposed wafer on which the pre-exposure was performed after the first pre-exposed wafer.

20. A method for manufacturing an electronic device, comprising: a first step of setting a wavelength of a first pulsed laser light for scanning a first scan field of a first semiconductor wafer to a first pattern that varies depending on a position in the field along a scan direction in the first scan field, based on a measurement result relating to a position shift of an exposure result by pre-exposure using an exposure apparatus, and setting a wavelength of a second pulsed laser light for scanning a second scan field of the first semiconductor wafer to a second pattern that varies depending on a position in the field along a scan direction in the second scan field and is different from the first pattern; and a second step of scanning the first scan field with the first pulsed laser light using the exposure apparatus, and then scanning the second scan field with the second pulsed laser light, in order to manufacture an electronic device.

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