Method for manufacturing electronic device

Abstract

A method for manufacturing an electronic device according to one aspect of the present disclosure includes the following steps: determining a magnification as a distortion component in a scanning width direction orthogonal to a scanning direction based on a pattern formed in a scanning field of a chip; measuring the chip height at multiple points in the scanning field to determine an average value of the chip height in the scanning width direction; determining a wavelength range of a pulsed laser that exhibits an allowable CD value at a focus position based on the average value of the chip height; determining a first wavelength of the pulsed laser that exhibits the determined magnification; determining a target wavelength based on the wavelength range and the first wavelength; and outputting a pulsed laser controlled so that the wavelength of each pulse becomes the target wavelength from a laser device to perform exposure in the scanning field of the chip.

Description

Technical Field

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

[0002] In recent years, semiconductor exposure equipment has been required to achieve higher resolution as semiconductor integrated circuits become increasingly miniaturized and highly integrated. Consequently, there has been a trend toward shorter wavelengths of light emitted from exposure light sources. For example, gas laser devices used for exposure include KrF excimer lasers, which output laser light with a wavelength of approximately 248 nm, and ArF excimer lasers, which output laser light with a wavelength of approximately 193 nm.

[0003] The spectral line width of the natural oscillation light of KrF excimer laser devices and ArF excimer laser devices is relatively wide, approximately 350 to 400 pm. Therefore, when a projection lens is constructed using a material that transmits ultraviolet light such as KrF and ArF lasers, chromatic aberration may sometimes occur. As a result, the resolution may be reduced. Therefore, it is necessary to narrow the spectral line width of the laser light output from the gas laser device to a level where chromatic aberration is invisible. Therefore, in order to narrow the spectral line width, a narrowing module (Line Narrow Module: LNM) containing narrowing elements (etalon, grating, etc.) is sometimes included in the laser resonator of the gas laser device. Hereinafter, a gas laser device with a narrowed spectral line width is referred to as a narrowed gas laser device.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-076995

[0007] Patent Document 2: U.S. Patent Application Publication No. 2018 / 0159297

[0008] Patent Document 3: U.S. Patent Application Publication No. 2015 / 0070673

[0009] Patent Document 4: U.S. Patent Application Publication No. 2011 / 0205512 Summary of the Invention

[0010] According to one aspect of the present disclosure, a method for manufacturing an electronic device includes the steps of scanning and exposing a pulsed laser on a chip in an exposure device, wherein the method for manufacturing the electronic device includes the following steps: determining a magnification as a distortion component in a scanning width direction orthogonal to a scanning direction based on a pattern formed on the chip in a scanning field of the chip; measuring the chip height at multiple points in the scanning field of the chip, and determining an average value of the chip height in the scanning width direction in the scanning field based on the measurement results of the chip height; determining a wavelength range of the pulsed laser that exhibits an allowable critical dimension (CD) value at a focus position based on the average value of the chip height; determining a first wavelength of the pulsed laser that exhibits the magnification; determining a target wavelength of the pulsed laser based on the wavelength range and the first wavelength; generating a pulsed laser by a laser device in such a manner that the wavelength of each pulse becomes a target wavelength, and outputting the pulsed laser to the exposure device; and exposing the pulsed laser in the scanning field of the chip.

[0011] Another aspect of the present disclosure provides a method for manufacturing an electronic device, which includes the steps of scanning and exposing a pulsed laser on a wafer in an exposure device, wherein the method for manufacturing an electronic device includes the following steps: determining a magnification as a distortion component in a scanning width direction orthogonal to a scanning direction based on a pattern formed on the wafer in a scanning field of the wafer; measuring focus positions at multiple points in the scanning field of the wafer, and determining an average value of the focus positions in the scanning width direction in the scanning field based on the measurement results of the focus positions; determining a wavelength range of the pulsed laser that exhibits an allowable critical dimension (CD) value at the average value of the focus positions; determining a first wavelength of the pulsed laser that exhibits the magnification; determining a target wavelength of the pulsed laser based on the wavelength range and the first wavelength; generating a pulsed laser by a laser device in such a manner that the wavelength of each pulse becomes a target wavelength, and outputting the pulsed laser to the exposure device; and exposing the pulsed laser in the scanning field of the wafer.

[0012] Another aspect of the present disclosure provides a method for manufacturing an electronic device that includes the steps of scanning and exposing a pulsed laser on a wafer in an exposure device, wherein the method for manufacturing the electronic device includes the following steps: determining a magnification as a distortion component in a scanning width direction orthogonal to a scanning direction based on a pattern formed on the wafer in a scanning field of the wafer; measuring focus positions at multiple points in the scanning field of the wafer, and determining an average value of focus positions in a direction orthogonal to the scanning direction in the scanning field based on the focus position measurement results; determining a first wavelength of the pulsed laser that exhibits the magnification; setting a target wavelength of the pulsed laser to the first wavelength; determining a target focus position at which a critical dimension (CD) value is within an allowable range when the wavelength of the pulsed laser is the first wavelength; controlling the wafer stage of the exposure device based on the target focus position; generating a pulsed laser by a laser device in such a manner that the wavelength of each pulse becomes a target wavelength, and outputting the pulsed laser to the exposure device; and exposing the pulsed laser in the scanning field of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Hereinafter, several embodiments of the present disclosure will be described as simple examples with reference to the accompanying drawings.

[0014] Figure 1 Schematic diagram showing distortion.

[0015] Figure 2 A schematic diagram showing magnification distortion.

[0016] Figure 3 A schematic diagram showing an exemplary exposure and measurement flow in a semiconductor manufacturing process.

[0017] Figure 4 The configuration of an exposure system of a comparative example is schematically shown.

[0018] Figure 5 An example of the output pattern of the light emission trigger signal Tr sent from the exposure control section to the laser control section is shown.

[0019] Figure 6 An example of an exposure pattern of step and scan exposure on a wafer is shown.

[0020] Figure 7 The relationship between one scan field and the static exposure area on the wafer is shown.

[0021] Figure 8 This diagram illustrates the static exposure area.

[0022] Figure 9 An example of the structure of a laser device is schematically shown.

[0023] Figure 10 It is an explanatory diagram showing, by way of example, the Y-axis direction dependency of the wafer height within the scanning field and the Y-axis direction dependency of the magnification in the X-axis direction.

[0024] Figure 11 An example configuration of a photolithography system according to the first embodiment is schematically shown.

[0025] Figure 12 This is a flowchart showing an example of the processing content of the lithography control unit in the first embodiment.

[0026] Figure 13 This is a flowchart showing an example of the processing content of the exposure control unit in the first embodiment.

[0027] Figure 14 1 is an explanatory diagram illustrating the magnification βcy in the X-axis direction at each position in the Y-axis direction within the scan field.

[0028] Figure 15This is an explanatory diagram showing, by way of example, the relationship between the average value of the height of the wafer in the X-axis direction at each position in the Y-axis direction within the scanning field and the focus position.

[0029] Figure 16 is shown to be applied to Figure 12 This is a flowchart of an example of a subroutine of step S13.

[0030] Figure 17 This is a diagram showing the magnification βcy(n) calculated according to the pulse number n in the scan field.

[0031] Figure 18 : is a graph showing an example of data stored in file A1.

[0032] Figure 19 is shown to be applied to Figure 12 This is a flowchart of an example of a subroutine of step S14.

[0033] Figure 20 Schematic diagram of wafer height measurement points within the scanning field SF.

[0034] Figure 21 : is a graph showing an example of data stored in file A2.

[0035] Figure 22 Graph showing an example of the relationship between CD and focus position when a dense pattern is exposed.

[0036] Figure 23 Graph showing an example of the relationship between CD and focus position when an isolated pattern is exposed.

[0037] Figure 24 is shown to be applied to Figure 12 This is a flowchart of an example of a subroutine of step S15.

[0038] Figure 25 An example of a list showing the relationship among exposure condition parameters, magnification βcy, and CD values stored in file A0 is shown.

[0039] Figure 26 is shown to be applied to Figure 12 A flowchart of an example of a subroutine of step S16 is shown.

[0040] Figure 27 is shown to be applied to Figure 26 Flowchart of an example of the subroutine of step S62.

[0041] Figure 28 : is a diagram showing an example of a data table stored in file B.

[0042] Figure 29 is shown to be applied to Figure 27 This is a flowchart of an example of a subroutine of step S71.

[0043] Figure 30 : is a diagram showing an example of table data stored in file C.

[0044] Figure 31 It shows Figure 30 Graph showing an example of a CD curve obtained in step S82.

[0045] Figure 32 is shown to be applied to Figure 27 This is a flowchart of an example of a subroutine of step S72.

[0046] Figure 33 : is a diagram showing an example of table data stored in file D.

[0047] Figure 34 It shows Figure 32 Graph showing an example of the approximate curve F obtained in step S92.

[0048] Figure 35 This is an explanatory diagram schematically showing an example of measurement points on a wafer by a focus sensor arranged in an exposure device of a lithography system according to a second embodiment.

[0049] Figure 36 This is a side view schematically showing a configuration example of an AF sensor unit of an exposure device applied to a photolithography system according to the second embodiment.

[0050] Figure 37 This is a flowchart showing an example of the processing content of the lithography control unit in the lithography system of embodiment 2.

[0051] Figure 38 This is a flowchart showing an example of the processing content of the exposure control unit in the lithography system according to the second embodiment.

[0052] Figure 39 is shown to be applied to Figure 38 A flowchart of an example of a subroutine of step S104 is shown.

[0053] Figure 40 An example configuration of a photolithography system according to a third embodiment is schematically shown.

[0054] Figure 41 This is a flowchart showing an example of the processing content of the exposure control unit in the lithography system according to the third embodiment.

[0055] Figure 42 is shown to be applied to Figure 41 A flowchart of an example of a subroutine of step S106A.

[0056] Figure 43 is shown to be applied to Figure 42 Flowchart of an example of a subroutine of step S141 and step S142.

[0057] Figure 44 A configuration example of a photolithography system according to a fourth embodiment is schematically shown.

[0058] Figure 45 This is a flowchart showing an example of the processing content of the exposure control unit in the lithography system of the fourth embodiment.

[0059] Figure 46 is shown to be applied to Figure 45 A flowchart of an example of a subroutine of step S106B is shown.

[0060] Figure 47 is shown to be applied to Figure 46 Flowchart of an example of a subroutine of step S146 and step S147.

[0061] Figure 48 : is a diagram showing an example of table data stored in file E.

[0062] Figure 49 It shows Figure 47 Graph showing an example of the approximate curve G obtained in step S172.

[0063] Figure 50 This is a flowchart showing an example of the processing content of the exposure control unit according to the modification of the fourth embodiment.

[0064] Figure 51 is shown to be applied to Figure 50 A flowchart of an example of a subroutine of step S106C.

[0065] Figure 52 A configuration example of a photolithography system according to a fifth embodiment is schematically shown.

[0066] Figure 53 This is a flowchart showing an example of the processing content of the exposure control unit in the lithography system of embodiment 5.

[0067] Figure 54 is shown to be applied to Figure 53 A flowchart of an example of a subroutine of step S106E.

[0068] Figure 55 It is a graph showing an example of the relationship between the CD value and the dose.

[0069] Figure 56 is shown to be applied to Figure 53A flowchart of an example of a subroutine of step S107 is shown.

[0070] Figure 57 Another structural example of a laser device is schematically shown.

[0071] Figure 58 An example configuration of a semiconductor laser system is schematically shown.

[0072] Figure 59 A conceptual diagram of the spectral line width achieved through chirping.

[0073] Figure 60 This is a schematic diagram showing the relationship between the current flowing through a semiconductor laser, wavelength change due to chirp, spectrum waveform, and light intensity.

[0074] Figure 61 This is a graph for explaining the rise time of a semiconductor optical amplifier.

[0075] Figure 62 An example configuration of an exposure device is schematically shown. DETAILED DESCRIPTION

[0076] -Table of contents-

[0077] 1. Explanation of terms

[0078] 2. Overview of Exposure and Measurement Processes in Semiconductor Manufacturing

[0079] 3. Overview of the Exposure System of the Comparative Example

[0080] 3.1 Structure

[0081] 3.2 Action

[0082] 3.3 Example of Exposure Action on a Wafer

[0083] 3.4 Relationship between Scanning Field and Static Exposure Area

[0084] 3.5 Examples of Laser Devices

[0085] 3.5.1 Structure

[0086] 3.5.2 Action

[0087] 3.5.3 Others

[0088] 4.Topic

[0089] 5. Implementation Method 1

[0090] 5.1 Structure

[0091] 5.2 Action

[0092] 5.2.1 Overview of Photolithography System Operation

[0093] 5.2.2 Example of Processing Contents of the Lithography Control Unit

[0094] 5.2.3 Example of processing content of exposure control unit

[0095] 5.2.4 Explanation of X-axis magnification βcy and focus position Fcy

[0096] 5.2.5 Example of a subroutine to calculate and save the magnification βcy in the X-axis direction

[0097] 5.2.6 Example of a subroutine for calculating and saving the focus position Fcy

[0098] 5.2.7 Average value of wafer height

[0099] 5.2.8 Example of a subroutine to store the relationship between exposure conditions and CD values

[0100] 5.2.9 Example of a subroutine to calculate the target wavelength λt of each pulse based on the magnification βcy, focus position Fcy, and CD

[0101] 5.3 Effect

[0102] 6. Implementation Method 2

[0103] 6.1 Structure

[0104] 6.2 Action

[0105] 6.2.1 Example of Processing Contents of the Lithography Control Unit

[0106] 6.2.2 Example of processing content of exposure control unit

[0107] 6.3 Effect

[0108] 7. Implementation Method 3

[0109] 7.1 Structure

[0110] 7.2 Actions

[0111] 7.3 Effect

[0112] 7.4 Variations

[0113] 8. Implementation Method 4

[0114] 8.1 Structure

[0115] 8.2 Actions

[0116] 8.3 Effect

[0117] 8.4 Variation 1

[0118] 8.5 Variation 2

[0119] 9. Implementation Method 5

[0120] 9.1 Structure

[0121] 9.2 Actions

[0122] 9.3 Effect

[0123] 9.4 Variations

[0124] 9.5 Other

[0125] 10. Examples of Excimer Laser Devices Using Solid-State Laser Devices as Oscillators

[0126] 10.1 Structure

[0127] 10.2 Actions

[0128] 10.3 Description of Semiconductor Laser Systems

[0129] 10.3.1 Structure

[0130] 10.3.2 Action

[0131] 10.4 Effect

[0132] 10.5 Variations

[0133] 10.6 Other

[0134] 11. Hardware structure of various control units

[0135] 12. Method for manufacturing electronic devices

[0136] 13. Others

[0137] Below, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The embodiments described below illustrate several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and actions described in each embodiment are not necessarily all required structures and actions of the present disclosure. In addition, the same reference numerals are given to the same structural elements, and repeated descriptions are omitted.

[0138] 1. Explanation of terms

[0139] The terms used in this disclosure are defined as follows.

[0140] Critical Dimension (CD) refers to the size of a fine pattern formed on a wafer such as a semiconductor.

[0141] Overlay (superposition) refers to the overlapping of fine patterns formed on a wafer such as a semiconductor.

[0142] The spectral line width Δλ is an index value of the spectral line width that affects exposure performance. The spectral line width Δλ may be, for example, a bandwidth where the integrated energy of the laser spectrum reaches 95%.

[0143] The Optical Proximity Effect (OPE) is a phenomenon in which the size of patterns exposed on a wafer changes depending on the distance between them. For example, if lines of the same size on a mask are densely packed or isolated, the resulting sizes on the wafer will differ.

[0144] Reference Figure 1 and Figure 2 Distortion and its component, magnification distortion, will be described. Figure 1 Schematic diagram showing distortion. Figure 1 The solid lines represent the ideal grid on the wafer (the locations that should be exposed), and the dashed lines represent the actual exposed locations. When using an exposure device to expose a semiconductor wafer, for example, the scanning field may not be a perfect rectangle due to various reasons. Distortion also occurs within the scanning field, and the pattern may sometimes deviate from its intended location, such as the grid. This is called distortion. Causes of distortion include aberrations in the projection optical system, the synchronization accuracy between the wafer stage and the reticle stage during scanning exposure, and deformation of the wafer caused by the wafer chuck.

[0145] Magnification distortion refers to the component of the distortion described above where the positional shift is proportional to the pattern's coordinates. This distortion is also referred to simply as "magnification." Generally speaking, information about "magnification" is obtained by decomposing distortion into components such as "simple displacement," "magnification," and "higher-order fluctuations." In other words, magnification is one component of distortion. Figure 2 A schematic diagram showing magnification distortion is shown in FIG. Figure 2 In the figure, the horizontal direction is set as the X-axis direction and the vertical direction is set as the Y-axis direction. Figure 2 The amount of displacement in the X-axis direction of the position indicated by the dotted line (the actual exposed position) relative to the ideal grid indicated by the solid line is proportional to the distance from the center in the X-axis direction. The same applies to the Y-axis direction. However, the X-axis and Y-axis directions do not necessarily have to be in the same direction or have the same proportionality factor.

[0146] The term "parallel" in this specification may include the concept of "approximately parallel" to the extent that it can be considered substantially parallel in a technical sense. Furthermore, the term "perpendicular" or "orthogonal" in this specification may include the concept of "approximately perpendicular" or "approximately orthogonal" to the extent that it can be considered substantially perpendicular or substantially orthogonal in a technical sense.

[0147] 2. Overview of Exposure and Measurement Processes in Semiconductor Manufacturing

[0148] Figure 3 A schematic diagram illustrates the exposure and measurement flow in an exemplary semiconductor manufacturing process. When a new layer is exposed to a wafer WF after the previous layer has been exposed and developed by the exposure device 14, the wafer WF to be exposed is measured to obtain height information and distortion information including magnification, and feedforward control is performed based on the measurement results. Wafer WF measurement is performed using the measurement function of the exposure device that exposed the previous layer or a dedicated measuring device.

[0149] The measurement items include wafer WF height information and the position information of the overlay mark of the previous layer. The wafer WF height information refers to the position (height) in the thickness direction of the wafer WF, i.e., the Z direction, also known as Z information. The distortion factor is calculated based on the overlay mark position information of the previous layer.

[0150] Key points of feedforward control include, for example, control of the vertical position of the wafer (Z-direction position), the relative scanning speed between the wafer and the reticle (mask), and the magnification of the projection optical system.

[0151] On the other hand, since exposure is performed later, the CD information is controlled based on feedback information from the previous wafer. The key points of feedback control are, for example, the vertical position of the wafer and the exposure amount, but in practice, in most cases, only the exposure amount is used.

[0152] A portion of the wafer WF exposed by the exposure device 14 is sampled and CD is measured using, for example, a CD-SEM (Critical Dimension-Scanning Electron Microscope).

[0153] 3. Overview of the Exposure System of the Comparative Example

[0154] 3.1 Structure

[0155] Figure 4 The structure of a comparative example exposure system 10 is schematically shown. The comparative examples disclosed herein are methods known only to the applicant and are not publicly known examples acknowledged by the applicant. Exposure system 10 includes a laser device 12 and an exposure device 14. Laser device 12 is a wavelength-variable narrowband ArF laser device and includes a laser control unit 20, a laser cavity (not shown), and a narrowband module.

[0156] Exposure device 14 includes exposure control unit 40, beam transfer unit (BDU) 42, high reflective mirror 43, illumination optical system 44, reticle 46, reticle stage 48, projection optical system 50, wafer holder 52, and wafer stage 54. "Reticle" is synonymous with "mask".

[0157] Wafer WF is held by wafer holder 52. Illumination system 44 guides pulsed laser light to reticle 46. Illumination system 44 shapes the laser beam into a substantially rectangular scanning beam with a uniform light intensity distribution. Furthermore, illumination system 44 controls the angle of incidence of the laser beam on reticle 46. Projection system 50 forms an image of the reticle pattern on wafer WF.

[0158] The exposure control unit 40 is connected to the reticle stage 48 and the wafer stage 54. Furthermore, the exposure control unit 40 is connected to the laser control unit 20. Each of the exposure control unit 40 and the laser control unit 20 is configured using a processor (not shown) and includes a storage device such as a memory. The storage device may also be incorporated into the processor.

[0159] 3.2 Action

[0160] The exposure control unit 40 transmits the target wavelength λt to the laser device 12 for each burst.

[0161] The laser control unit 20 controls the wavelength selection of the narrowband module so that the wavelength λ of the pulsed laser light output from the laser device 12 reaches the target wavelength λt, controls the excitation intensity so that the pulse energy E reaches the target pulse energy Et, and outputs the pulsed laser light in accordance with the emission trigger signal Tr. Furthermore, the laser control unit 20 transmits various measurement data of the pulsed laser light output in accordance with the emission trigger signal Tr to the exposure control unit 40. Examples of such measurement data include the wavelength λ and the pulse energy E.

[0162] The exposure control unit 40 transmits target laser control parameters to the laser control unit 20 for each burst in a step-and-scan manner. While transmitting a light emission trigger signal Tr, the exposure control unit 40 controls the reticle stage 48 and wafer stage 54, thereby scanning the image of the exposure reticle 46 onto the wafer WF. The target laser control parameters include, for example, the target wavelength λt and the target pulse energy Et. The term "target laser" refers to the target pulse laser. "Pulsed laser" is sometimes simply referred to as "laser."

[0163] 3.3 Example of Exposure Action on a Wafer

[0164] Figure 5 FIG. 4 shows an example of an output pattern of the light emission trigger signal Tr sent from the exposure control unit 40 to the laser control unit 20. Figure 5In the example shown, after performing a conditioning oscillation for each wafer WF, the laser device 12 enters the actual exposure mode. Specifically, the laser device 12 initially performs a conditioning oscillation, and after a predetermined time interval, a burst operation is performed to expose the first wafer (wafer #1).

[0165] Adjustment oscillation refers to oscillation that outputs pulsed laser light for adjustment, while not irradiating the wafer WF with pulsed laser light. Adjustment oscillation is performed under specified conditions until the laser stabilizes and is ready for exposure. Adjustment oscillation is performed before each wafer production batch. Pulsed laser light is output at a specified frequency, for example, of several hundred Hz to several kHz. During wafer exposure, burst operation is typically performed, with burst periods and oscillation rest periods repeated. Burst operation is also performed during adjustment oscillation.

[0166] exist Figure 5 In the pulse-intensive interval, the burst period is the period during which pulse laser is continuously output for a specified period. Figure 5 The intervals without pulses are oscillation rest periods. Furthermore, during the adjustment oscillation, the lengths of each continuous pulse output period do not need to be constant; for adjustment purposes, the continuous output operation can be performed with varying lengths of each continuous output period. After the adjustment oscillation, the first wafer (wafer #1) is exposed in exposure device 14 at relatively large intervals.

[0167] Figure 6 An example of the exposure pattern of step and scan exposure on the wafer WF is shown. Figure 6 The plurality of rectangular areas shown in the wafer WF are scanning fields SF. The scanning field SF is the exposure area of one scanning exposure, and is also called a scanning area. Figure 6 As shown, the chip WF is divided into multiple exposure areas (scanning fields) of specified sizes, and each exposure area is scanned and exposed during the period between the start (chip start) and end (chip end) of chip exposure, thereby performing chip exposure.

[0168] That is, during wafer exposure, the following steps are repeated: a first predetermined exposure area of wafer WF is exposed by a first scanning exposure (scan #1), followed by a second predetermined exposure area exposed by a second scanning exposure (scan #2). During a single scanning exposure, multiple pulsed lasers (pulse #1, pulse #2, ...) can be continuously output from the laser device 12. This scanning exposure is repeated sequentially. After scanning exposure of all exposure areas of the first wafer WF is completed, oscillation is adjusted again, and wafer exposure of the second wafer WF (wafer #2) is then performed.

[0169] according to Figure 6The step-and-scan exposure is performed in the order of the dashed arrows shown until wafer start → scan #1 → scan #2 → ... → scan #126 → wafer end. Wafer WF is an example of a semiconductor substrate (photosensitive substrate) coated with a resist.

[0170] 3.4 Relationship between Scanning Field and Static Exposure Area

[0171] Figure 7 The relationship between one scanning field SF on wafer WF and the static exposure area SEA is shown. The static exposure area SEA is a roughly rectangular beam irradiation area with a roughly uniform light intensity distribution used in the scanning exposure of the scanning field SF. The roughly rectangular, roughly uniform scanning beam shaped by the illumination optical system 44 is irradiated onto the reticle 46. In the short axis direction of the scanning beam (here, the Y-axis direction), the reticle 46 and wafer WF are moved in different directions in the Y-axis direction according to the reduction ratio of the projection optical system 50, while exposure is performed. As a result, the reticle pattern is scan-exposed in each scanning field SF on wafer WF. The static exposure area SEA can also be understood as an area that can be uniformly exposed by the scanning beam. The area that can be uniformly exposed can also be referred to as the statically exposed area.

[0172] exist Figure 7 In the figure, the direction toward the negative side of the Y-axis in the longitudinal direction is the scanning direction, and the direction toward the positive side of the Y-axis is the chip moving direction (stage moving direction). Figure 7 The direction parallel to the paper surface and perpendicular to the Y-axis direction (X-axis direction) is called the scan width direction. The size of the scan field SF on the wafer WF is, for example, 33 mm in the Y-axis direction and 26 mm in the X-axis direction.

[0173] Figure 8 This diagram illustrates the static exposure area SEA. Let Bx be the length of the static exposure area SEA in the X-axis direction and By be its width in the Y-axis direction. Bx corresponds to the X-axis dimension of the scanning field SF, while By is significantly smaller than the Y-axis dimension of the scanning field SF. The Y-axis width By of the static exposure area SEA is referred to as the N-gap. The number of pulses NSL to expose the resist on the wafer WF is expressed as follows.

[0174] NSL=(By / Vy)·f

[0175] Vy: The scanning speed of the wafer in the Y-axis direction

[0176] f: laser repetition frequency (Hz)

[0177] 3.5 Examples of Laser Devices

[0178] 3.5.1 Structure

[0179] Figure 9 An example configuration of the laser device 12 is schematically shown. Figure 9 The laser device 12 shown is a narrowband ArF laser device, comprising a laser control unit 20, an oscillator 22, an amplifier 24, a monitor module 26, and a gate 28. The oscillator 22 comprises a cavity 60, an output coupling mirror 62, a pulse power module (PPM) 64, a charger 66, and a narrowband module (LNM) 68.

[0180] Cavity 60 includes windows 71 and 72, a pair of electrodes 73 and 74, and an electrically insulating member 75. PPM 64 includes a switch 65 and a charging capacitor (not shown), which is connected to electrode 74 via a feed channel through electrically insulating member 75. Electrode 73 is connected to cavity 60, which is grounded. Charger 66 charges the charging capacitor of PPM 64 in accordance with instructions from laser control unit 20.

[0181] The narrowband module 68 and the output coupling mirror 62 constitute an optical resonator. The cavity 60 is configured so that a discharge region of a pair of electrodes 73 and 74 is located on the optical path of the resonator. The output coupling mirror 62 is coated with a multilayer film that reflects a portion of the laser light generated in the cavity 60 and transmits the remaining portion.

[0182] The narrowband module 68 includes two prisms 81 and 82, a grating 83, and a rotation stage 84 for rotating the prism 82. The narrowband module 68 rotates the prism 82 using the rotation stage 84, thereby changing the angle of incidence on the grating 83 and controlling the oscillation wavelength of the pulsed laser light. The rotation stage 84 may also include a piezoelectric element capable of high-speed response, responding to each pulse.

[0183] Amplifier 24 includes optical resonator 90, cavity 160, PPM 164, and charger 166. The structures of cavity 160, PPM 164, and charger 166 are identical to the corresponding elements of oscillator 22. Cavity 160 includes windows 171 and 172, a pair of electrodes 173 and 174, and an electrically insulating member 175. PPM 164 includes switch 165 and a charging capacitor (not shown).

[0184] Optical resonator 90 is a Fabry-Perot type optical resonator, consisting of a rear mirror 91 and an output coupling mirror 92. Rear mirror 91 partially reflects a portion of the laser light and transmits another portion. Output coupling mirror 92 also partially reflects a portion of the laser light and transmits another portion. The reflectivity of rear mirror 91 is, for example, 80% to 90%. The reflectivity of output coupling mirror 92 is, for example, 10% to 30%.

[0185] The monitor module 26 includes beam splitters 181 and 182, a spectrum detector 183, and a light sensor 184 for detecting the laser pulse energy E. The spectrum detector 183 may be, for example, an etalon spectrometer, etc. The light sensor 184 may be, for example, a photodiode, etc.

[0186] 3.5.2 Action

[0187] After receiving the data of the target wavelength λt and the target pulse energy Et from the exposure control unit 40, the laser control unit 20 controls the rotation stage 84 of the LNM 68 to make the output wavelength become the target wavelength λt, and controls at least the charger 166 of the amplifier 24 to make the pulse energy become the target pulse energy Et.

[0188] After receiving the emission trigger signal Tr from the exposure control unit 40, the laser control unit 20 applies trigger signals to the switches 165 and 65 of the PPM 164 and 64, respectively, to cause discharge when the pulsed laser light output from the oscillator 22 enters the discharge space of the cavity 160 of the amplifier 24. As a result, the pulsed laser light output from the oscillator 22 is amplified and oscillated by the amplifier 24. The amplified pulsed laser light is sampled by the beam splitter 181 of the monitor module 26, and the pulse energy E and wavelength λ are measured.

[0189] The laser control unit 20 obtains data on the pulse energy E and wavelength λ measured using the monitor module 26, and controls the charging voltage of the charger 166 and the oscillation wavelength of the oscillator 22 so that the difference between the pulse energy E and the target pulse energy Et, and the difference between the wavelength λ and the target wavelength λt are close to 0.

[0190] The laser control unit 20 can control the pulse energy E and the wavelength λ in pulse units.

[0191] The pulsed laser light transmitted through the beam splitter 181 of the monitor module 26 enters the exposure device 14 via the gate 28. By controlling the delay time Δt between the discharge timing of the cavity 60 of the oscillator 22 and the cavity 160 of the amplifier 24, the line width Δλ of the pulsed laser light output from the laser device 12 can be controlled.

[0192] 3.5.3 Others

[0193] exist Figure 9 In FIG. 1 , an example of a Fabry-Perot resonator is shown as the optical resonator 90 , but an amplifier including a ring resonator may also be used.

[0194] 4.Topic

[0195] In the comparative example exposure system 10, the target wavelength λt of the burst pulse in the scanning exposure of scan #k is calculated for each burst so as to achieve a focus position corresponding to the average height of the wafer WF. The target wavelength data is sent to the laser control unit 20, and the scanning exposure is performed.

[0196] However, in the scanning field SF of the scan #k, the chip height Hcy in the scanning direction (Y-axis direction) changes (refer to Figure 10 ), therefore, a focus position shift sometimes occurs in an area that shifts from the average value (average height).

[0197] Furthermore, when the superposition accuracy is made high, there is also a change in the magnification βcy in the direction (X-axis direction) perpendicular to the scanning direction (see Figure 10 As shown in the curve G2 in the lower section, it is also necessary to correct the magnification βcy in the X-axis direction.

[0198] Figure 10 It is an explanatory diagram showing, by way of example, the Y-axis direction dependency of the wafer height Hcy within the scanning field SF and the Y-axis direction dependency of the magnification βcy in the X-axis direction.

[0199] Figure 10 The upper part of schematically shows the state of scanning exposure of the scanning field SF of scan #k. Figure 10 The middle section shows graph G1 and the average wafer height. Graph G1 represents the Y-axis dependence of the wafer height Hcy in the scan field SF of scan #k, which is actually measured. The average wafer height here may be the average value of the heights within the scan field SF of scan #k or the average value of the height of the entire wafer WF.

[0200] Figure 10 The lower part of FIG. 1 shows a graph G2 and a standard magnification. The graph G2 shows the Y-axis direction dependency of the magnification βcy in the X-axis direction in the scan field SF of the scan #k that is actually measured.

[0201] like Figure 10 As shown, it is a problem to balance the correction of the magnification βcy within the scanning field SF due to the change in the wavelength of each laser pulse and the correction of the focus position.

[0202] 5. Implementation Method 1

[0203] 5.1 Structure

[0204] Figure 11 The following schematically shows an example configuration of the photolithography system 100 according to the first embodiment. Figure 11 The structure shown is Figure 4 The differences are explained. Figure 11The lithography system 100 shown is a Figure 4 The configuration of the exposure system 10 shown is an overall system in which a wafer inspection device 310 and a lithography control unit 110 are added.

[0205] The wafer inspection apparatus 310 irradiates light onto the wafer WF and measures the reflected or diffracted light, thereby enabling measurement of the CD, wafer WF height, and wafer overlay. Alternatively, the wafer inspection apparatus 310 may be a high-resolution scanning electron microscope (SEM). The wafer inspection apparatus 310 includes a wafer inspection control unit 320, a wafer holder 352, and a wafer stage 354. The wafer inspection apparatus 310 is an example of an "inspection apparatus" in this disclosure. The wafer inspection apparatus 310 may also include multiple measuring instruments.

[0206] The lithography control unit 110 is configured using a processor (not shown). The lithography control unit 110 includes a storage device such as a memory. The processor may also include a storage device. Signal lines are connected to the lithography control unit 110 for transmitting and receiving data, etc., between the lithography control unit 110 and the wafer inspection control unit 320, the exposure control unit 40, and the laser control unit 20.

[0207] Furthermore, the exposure device 14 in the photolithography system 100 includes a focus sensor 58 for measuring the height of the wafer WF. The focus sensor 58 is connected to the exposure control unit 40 .

[0208] 5.2 Action

[0209] 5.2.1 Overview of Photolithography System Operation

[0210] The wafer inspection device 310 inspects the wafer WF before exposure, measures the height of each scanning field SF and the wafer WF within the scanning field SF, the position size of the processing pattern, etc., and sends the measurement data corresponding to each scanning field SF of the wafer WF to the lithography control unit 110.

[0211] The lithography control unit 110 calculates the focus position Fcy and the magnification βcy from the average value of the height of the wafer WF and the position of the pattern in a direction perpendicular to the scanning direction of each scanning field SF of the wafer WF.

[0212] The photolithography control unit 110 calculates the target wavelength λt based on the focus position Fcy, the magnification βcy, and the CD value that depend on the position of each scanning field SF in the scanning direction.

[0213] The lithography control unit 110 transmits the target wavelength λt of each pulse to the laser device 12 via the exposure control unit 40 of the exposure device 14 .

[0214] The action of exposure and Figure 4 The exposure systems 10 shown are identical.

[0215] 5.2.2 Example of Processing Contents of the Lithography Control Unit

[0216] Figure 12 This is a flowchart showing an example of the processing content of the photolithography control unit 110 in the first embodiment. The processor that functions as the photolithography control unit 110 executes the program, thereby realizing Figure 12 Steps shown.

[0217] In step S11, the lithography control unit 110 determines whether the inspection of the next wafer WF to be exposed by the wafer inspection apparatus 310 has been completed. After the wafer WF inspection is completed, the wafer inspection apparatus 310 transmits a wafer inspection completion signal to the lithography control unit 110. The lithography control unit 110 determines whether the inspection has been completed by receiving a wafer inspection completion signal from the wafer inspection apparatus 310 indicating the completion of the wafer inspection of the next wafer WF to be exposed.

[0218] If the result of the determination in step S11 is “No”, the lithography control unit 110 repeats step S11 .

[0219] If the result of determination in step S11 is “Yes”, the lithography control unit 110 proceeds to step S12 .

[0220] In step S12, the lithography control unit 110 receives inspection data of the wafer WF before exposure from the wafer inspection apparatus 310 and stores data D for each scan field SF. The data D includes information on the measured wafer height, position information on a mark on the wafer WF, information on the CD value, and information on the process for which the CD value is obtained. The data D is a data set that associates these pieces of information with information identifying the position of the measured scan field SF.

[0221] Next, in step S13 , the lithography control unit 110 calculates and stores the magnification βcy in the direction perpendicular to the scanning direction in each scanning field SF based on the data D.

[0222] Furthermore, in step S14 , the lithography control unit 110 calculates and stores a focus position Fcy based on the data D. The focus position Fcy is an average value of focus positions in a direction perpendicular to the scanning direction in each scanning field SF.

[0223] Furthermore, in step S15, the photolithography control unit 110 stores the relationship between the exposure condition and the CD value based on the data D. In addition, the order of the processing of steps S13 to S15 is not limited to Figure 12 The examples shown can be appropriately replaced, and multiple steps can also be processed in parallel.

[0224] Next, in step S16, the lithography control unit 110 calculates the target wavelength λt for each pulse within each scan field SF based on the magnification βcy, the focus position Fcy, and the CD. The CD value used in step S16 is feedback data obtained from pre-stored CD values of exposure results for different wafers WF previously exposed.

[0225] In step S17, the lithography control unit 110 sends the target wavelength λt of each pulse in each scan field SF to the exposure control unit 40. In this embodiment, the lithography control unit 110 sends the target wavelength λt data of each pulse in each scan field SF to the exposure control unit 40 in a batch.

[0226] Next, in step S18, the lithography control unit 110 determines whether there is a wafer WF to be exposed next. If the determination result in step S18 is "yes", the lithography control unit 110 returns to step S11.

[0227] On the other hand, if the result of the determination in step S18 is "No", the lithography control unit 110 ends the process. Figure 12 Flowchart of the process.

[0228] 5.2.3 Example of processing content of exposure control unit

[0229] Figure 13 This is a flowchart showing an example of the processing content of the exposure control unit 40 in the first embodiment. The processor that functions as the exposure control unit 40 executes the program, thereby realizing Figure 13 Steps shown.

[0230] In step S21, the exposure control unit 40 receives the target wavelength λt of each pulse in each scan field SF from the lithography control unit 110. In this embodiment, the exposure control unit 40 receives the target wavelength λt data of each pulse in each scan field SF from the lithography control unit 110 in a batch.

[0231] Next, in step S22, the exposure control unit 40 performs exposure within the scanning field SF while transmitting the target wavelength λt and the emission trigger signal Tr for each pulse to the laser control unit 20. Specifically, the exposure control unit 40 transmits the target wavelength λt and the emission trigger signal Tr to the laser control unit 20 for each pulse. At this time, the exposure control unit 40 moves the reticle 46 and wafer WF in opposite directions in synchronization with the emission trigger signal Tr to perform scanning exposure.

[0232] Next, in step S23, the exposure control unit 40 determines whether the exposure of the currently exposed scanning field SF has been completed. If the currently exposed scanning field SF is in the process of being scanned and an unexposed area remains within the scanning field SF, the determination result of step S23 becomes "No." If the determination result of step S23 is "No," the exposure control unit 40 returns to step S22 and continues the scanning exposure of the scanning field SF.

[0233] When the scanning exposure of the scanning field SF is completed and the determination result of step S23 is “Yes”, the exposure control unit 40 proceeds to step S24 .

[0234] In step S24, the exposure control unit 40 determines whether to expose the next scan field SF. If unexposed scan fields SF remain within the wafer WF, the determination in step S24 is "yes." If the determination in step S24 is "yes," the exposure control unit 40 proceeds to step S25.

[0235] In step S25, the exposure control unit 40 moves the wafer WF to the next scanning field SF. After step S25, the exposure control unit 40 returns to step S21.

[0236] On the other hand, if the determination result of step S24 is "No", the exposure control unit 40 ends Figure 13 Flowchart of the process.

[0237] 5.2.4 Explanation of X-axis magnification βcy and focus position Fcy

[0238] Here, the magnification βcy in the X-axis direction within the scanning field SF and the focus position Fcy calculated based on the average wafer height Havy in the X-axis direction will be described.

[0239] Figure 14 1 is an explanatory diagram showing, by way of example, the magnification βcy in the X-axis direction at each position in the Y-axis direction within the scanning field SF. Figure 14 The upper portion schematically illustrates how scanning field SF of wafer WF is scanned and exposed by scanning beam SB. The wavy lines at the ends of scanning field SF in the X-axis direction indicate positions that vary due to magnification βcy in the X-axis direction, which is a distortion component.

[0240] Figure 14 The graph G3 shown in the middle section is an example of the magnification βcy in the X-axis direction obtained from the inspection results of the wafer inspection apparatus 310 for the scanning field SF shown in the upper section. Figure 14The graph G4 shown in the lower section is obtained by converting the horizontal axis of the graph G3 shown in the middle section into the pulse number of the scanning exposure pulse. The pulse number of the scanning exposure pulse is a number indicating the order of the pulses irradiated in the scanning field SF.

[0241] Figure 15 This is an explanatory diagram showing, by way of example, the relationship between the average value Havy of the height of the wafer WF in the X-axis direction (hereinafter referred to as “wafer height average value”) at each position in the Y-axis direction within the scanning field SF and the focus position Fc. Figure 15 The upper section shows Figure 14 The same scanning field SF as the upper segment. Figure 15 Graph G5 shown below scan field SF is an example of the average wafer height Havy calculated based on the inspection results of wafer inspection apparatus 310 for scan field SF shown in the upper section. Graph G6 shown below graph G5 is a graph obtained by converting the horizontal axis of graph G5 into the pulse number of the scanning exposure pulse. Figure 15 The graph G7 shown in the lowermost section of FIG. 1 is an example of the focus position Fcy calculated based on the average wafer height Havy and the reference focus position F0.

[0242] like Figure 14 The curve graph G3 and Figure 15 As shown in the curve G5, the lithography control unit 110 calculates the X-axis magnification βcy at the Y-axis position (Y coordinate) in each scanning field SF and the average value of the height of the chip WF in the X-axis direction (chip height average Havy) based on the inspection results of the chip inspection device 310.

[0243] Then, the photolithography control unit 110 replaces the position in the Y-axis direction with the pulse number of the scanning exposure pulse in the scanning field SF, and replaces it with the data of the magnification βcy and the average wafer height Havy for the pulse number (see Figure 14 The curve graph G4 and Figure 15 G6).

[0244] Furthermore, the lithography control unit 110 calculates the focus position Fcy according to the wafer height average value Havy and the reference focus position F0 using the following formula (1) and performs substitution (refer to Figure 15 As shown in the graph G7, the focus position Fcy is the average value of the distance between the projection optical system 50 and the surface of the wafer WF in the X-axis direction.

[0245] Fcy=F0-Havy (1)

[0246] 5.2.5 Example of a subroutine to calculate and save the magnification βcy in the X-axis direction

[0247] Figure 16 is shown to be applied to Figure 12 This is a flowchart of an example of a subroutine of step S13. Figure 16 In step S31 , the lithography control unit 110 sets an index n indicating the pulse number of the pulsed laser light irradiated in one scan to 1. The index n being “1” indicates the pulse number of the first pulse irradiated in one scan.

[0248] Next, in step S32, the lithography control unit 110 calculates the X-axis magnification βcy(n) based on the processing pattern data of the wafer WF. Here, the Y-axis spacing of the measurement points preferably matches the distance L that the wafer WF moves during the pulse interval of the scanning beam SB. Assuming that the movement speed of the wafer WF is V and the repetition frequency of the laser beam of the scanning beam SB is f, the distance L is expressed by the following equation (2).

[0249] L=V·(1 / f) (2)

[0250] In step S33 , the lithography control section 110 writes the data of the magnification βcy(n) into the file A1 .

[0251] Next, in step S34 , the lithography control unit 110 determines whether the index n is equal to or greater than N. N, which serves as a comparison reference, is the pulse number of the last pulse irradiated in one scan.

[0252] If the result of the determination in step S34 is "No," the lithography control unit 110 proceeds to step S35. In step S35, the lithography control unit 110 increments the value of the index n and returns to step S32.

[0253] On the other hand, if the result of the determination in step S34 is “Yes”, the lithography control unit 110 ends the Figure 16 Flowchart of , returns Figure 12 The main process.

[0254] Figure 17 Schematic diagram of the magnification βcy(n) calculated for each pulse number n in each scanning field SF. The magnification βcy(n) corresponding to each of the pulse numbers 1 to N is calculated.

[0255] Figure 18 is a diagram showing an example of data stored in file A1. Figure 18 As shown, the file A1 stores data of the magnification βcy(n) corresponding to the pulse number n.

[0256] 5.2.6 Example of a subroutine for calculating and saving the focus position Fcy

[0257] Figure 19 is shown to be applied to Figure 12 This is a flowchart of an example of a subroutine of step S14. Figure 19 In step S41 , the lithography control unit 110 sets an index n indicating the pulse number of the pulsed laser light irradiated in one scan to 1.

[0258] Next, in step S42, the lithography control unit 110 calculates the average value Havy(n) of the wafer height Hc(n,m) in the X-axis direction at the Y-axis position corresponding to the irradiation position of the n-th pulse in the scanning field SF. m is an index indicating the X-axis position of the measurement point where the wafer height is measured by the wafer inspection device 310 (see Figure 20 As described above, the interval between the measurement points in the Y-axis direction is preferably consistent with the distance L that the wafer WF moves within the pulse interval of the scanning beam SB.

[0259] When M measurement points are set in the X-axis direction for each Y-axis position corresponding to a pulse number n (n=1 to N) in the scan field SF, m can take values from 1 to M.

[0260] The average wafer height Havy(n) is calculated using the following formula (3).

[0261] [Mathematical formula 1]

[0262]

[0263] Here, an example is shown in which a simple average value of Hc(n, m) is calculated as the wafer height average value Havy(n), but a weighted average value may be used as described later.

[0264] Next, in step S43 , the lithography control unit 110 calculates the focus position Fcy(n) according to the wafer height average value Havy(n) and the reference focus position F0 according to equation (4).

[0265] Fcy(n)=F0-Havy(n) (4)

[0266] Then, in step S44 , the lithography control section 110 writes the data of the focus position Fcy(n) into the file A2 .

[0267] Next, in step S45 , the lithography control unit 110 determines whether the index n is equal to or greater than N.

[0268] If the result of the determination in step S45 is "No," the lithography control unit 110 proceeds to step S46. In step S46, the lithography control unit 110 increments the value of the index n and returns to step S42.

[0269] On the other hand, if the result of the determination in step S45 is “Yes”, the lithography control unit 110 ends the process. Figure 19 Flowchart of , returns Figure 12 The main process.

[0270] Figure 20 Schematic diagram of wafer height measurement points within the scanning field SF. Figure 20 The black dots shown in the figure represent the wafer height measurement points. Figure 20 In FIG, the number of wafer height measurement points is omitted for illustration, but N×M wafer height measurement points are set in the scanning field SF. The wafer height Hc(n, m) represents the wafer height measured at the measurement point (n, m). Figure 20 In FIG, a plurality of measurement points represented by (n, m) is an example of “multiple points” in the present disclosure.

[0271] Figure 21 is a diagram showing an example of data stored in file A2. Figure 21 As shown, the file A2 stores data of the focus position Fcy(n) corresponding to the pulse number n.

[0272] 5.2.7 Average value of wafer height

[0273] like Figure 22 and Figure 23 As shown, the focus sensitivity varies depending on the shape of the mask pattern to be exposed. Figure 22 This is a graph showing an example of the relationship between CD and focus position when a dense pattern is exposed. The horizontal axis represents the defocus amount from the best focus position (0.0), and the vertical axis represents the CD value. Figure 22 The graph shown is an example of a CD-focus curve of 65 nm lines / 130 pitches as a dense pattern. Figure 23 This is a graph showing an example of the relationship between CD and focus position when an isolated pattern is exposed. The horizontal axis represents the defocus amount from the best focus position, and the vertical axis represents the CD value. Figure 23 The graph shown is an example of a CD-focus curve for a 65 nm line / 600 pitch isolated pattern.

[0274] like Figure 22 and Figure 23 As shown in FIG, the tendency of the CD-focus curve varies depending on the mask pattern to be exposed. In the case of a dense pattern, such as Figure 22 In this way, within the defocus range of ±210, the CD-focus curve is flat, that is, even if the focus position changes, the CD value hardly changes. On the other hand, in the case of an isolated pattern, as shown in FIG. Figure 23In this way, the CD-focus curve becomes a convex shape, and when the focus position changes, the CD value also changes greatly.

[0275] Therefore, when calculating the average of the chip height, it is not a simple average, but rather a weighted average is obtained by, for example, increasing the weight of the part with isolated patterns and reducing the weight of the part with dense patterns. In this way, control of the chip height can be performed with emphasis on patterns that are sensitive to focus, and the overall CD deviation can be suppressed.

[0276] This allows for weighted averaging, not just the sensitivity of the pattern to the focus position, but also, for example, increasing the weight of areas where patterns with a greater impact on chip performance are located. Unless otherwise specified, the term "average" in this specification is not limited to a simple average but also includes a weighted average.

[0277] 5.2.8 Example of a subroutine to store the relationship between exposure conditions and CD values

[0278] Figure 24 is shown to be applied to Figure 12 This is a flowchart of an example of a subroutine of step S15. Figure 24 In step S51, the lithography control unit 110 reads the CD value in each scanning field SF on the wafer WF measured by the wafer inspection device 310 from the data D. Figure 11 As described in , the CD values in each scanning field SF of the wafer WF are measured by the wafer inspection apparatus 310. The lithography control unit 110 reads these data D.

[0279] Next, in step S52, the lithography control unit 110 reads the measured exposure condition parameter data F for each scan field SF of the wafer WF. The data F is the exposure condition data received by the lithography control unit 110 from the exposure control unit 40 for the wafer WF to be exposed.

[0280] In step S53 , the lithography control unit 110 stores the relationship between the exposure condition parameters and the CD value in file A0 . That is, the lithography control unit 110 stores the relationship between the exposure condition parameters and the CD value in file A0 based on data D and data F.

[0281] Next, in step S54, the lithography control unit 110 organizes the relationships between exposure conditions and CD values from file A0 and stores the data in separate files. For example, the lithography control unit 110 organizes the relationships between exposure parameters and CD values for each exposure condition from file A0 and stores the data in files B, C, D, and E, which will be described later.

[0282] After step S54, the photolithography control unit 110 ends Figure 24 Flowchart of , returns Figure 12 The main process.

[0283] Figure 25 An example of a list showing the relationship among exposure condition parameters, magnification βcy, and CD values stored in file A0 is shown.

[0284] Here, the exposure condition parameters include, for example, the parameter IL of the illumination optical system 44 , the parameter PJ of the projection optical system 50 , the parameter M of the mask, the dose D, the wavelength λ, the line width Δλ, and the focus position Fcy.

[0285] Examples of the parameter IL of the illumination optical system 44 include σ (sigma) of normal illumination, σ of annular illumination, annular ratio, and the angle, position, and size of quadrupole illumination.

[0286] Examples of the parameter PJ of the projection optical system 50 are chromatic aberration correction, numerical aperture NA, and the like.

[0287] Examples of the mask parameter M include the size, material, and type of mask.

[0288] Figure 25 The illustrated parameters IL of the illumination optical system 44, PJ of the projection optical system 50, M of the mask, and D are exposure condition parameters received from the exposure device 14. The line width Δλ and wavelength λ are exposure condition parameters received from the exposure device 14 or the laser device 12. The magnification βcy and the focus position Fcy are parameters received from the exposure device 14 or the wafer inspection device 310. The CD value is a parameter received from the wafer inspection device 310.

[0289] Figure 24 Step S54 is, for example, a step of extracting data of the same exposure condition parameters from the data of file A0 and generating data of file B, file C, file D, file E, and the like.

[0290] Furthermore, the exposure condition parameters are not limited to the parameters exemplified above, and may include, for example, parameters of the resist, such as the type, sensitivity, thickness, and baking conditions of the resist.

[0291] 5.2.9 Example of a subroutine to calculate the target wavelength λt of each pulse based on the magnification βcy, focus position Fcy, and CD

[0292] Figure 26 is shown to be applied to Figure 12 A flowchart of an example of a subroutine of step S16 is shown.

[0293] In step S61 , the lithography control unit 110 sets an index n indicating the pulse number of the pulsed laser light irradiated in one scan to 1.

[0294] Next, in step S62 , the lithography control unit 110 determines the target wavelength λt(n) of the n-th pulse in the scanning field SF based on the magnification βcy(n), the focus position Fcy(n), and the CD.

[0295] Next, in step S63 , the lithography control section 110 determines whether the index n is equal to N.

[0296] If the result of the determination in step S63 is "No," the lithography control unit 110 proceeds to step S64. In step S64, the lithography control unit 110 increments the value of the index n and returns to step S62.

[0297] On the other hand, if the result of the determination in step S63 is “Yes”, the photolithography control unit 110 ends the process. Figure 26 Flowchart of , returns Figure 12 The main process.

[0298] Figure 27 is shown to be applied to Figure 26 This is a flowchart of an example of a subroutine of step S62. Figure 27 In step S71, the photolithography control unit 110 obtains the shortest wavelength λ in the wavelength range showing the allowable CD value at the focus position Fcy(n). S (n) and the longest wavelength λ L (n).

[0299] Next, in step S72, the photolithography control unit 110 determines the wavelength λ that exhibits the magnification βcy(n). M (n) In addition, the order of step S71 and step S72 can be reversed, and these steps can also be performed in parallel.

[0300] Next, in step S74, the photolithography control unit 110 determines the wavelength λ M (n) is the value that satisfies λ S (n)≤λ M (n)≤λ L (n), or λ M (n)<λs(n) or λ L (n)<λ M (n).

[0301] In step S74, the result of the determination is that S (n)≤λ M (n)≤λ L (n), the lithography control unit 110 proceeds to step S75 and determines the target wavelength λt(n) as λM (n).

[0302] In step S74, the result of the determination is M When λt(n)<λs(n), the photolithography control unit 110 proceeds to step S76 and determines the target wavelength λt(n) to be λ S (n).

[0303] In step S74, the result of the determination is L (n)<λ M (n), the lithography control unit 110 proceeds to step S77 and determines the target wavelength λt(n) as λ L (n).

[0304] After step S75 , step S76 , or step S77 , the photolithography control section 110 proceeds to step S78 .

[0305] In step S78, the lithography control unit 110 writes Fcy(n), λ S (n), λ L (n), βcy(n), λ M (n) and λt(n) data.

[0306] After step S78, the photolithography control unit 110 ends Figure 27 Flowchart of , returns Figure 26 Flowchart of the process.

[0307] Figure 28 : is a diagram showing an example of a data table stored in file B. Figure 28 As shown, for each pulse number n, a number including Fcy(n), λ S (n), λ L (n), βcy(n), λ M Record the data of (n) and λt(n).

[0308] Figure 29 is shown to be applied to Figure 27 This is a flowchart of an example of a subroutine of step S71. Figure 29 In step S81, the photolithography control unit 110 reads a file C of relationships between focus position Fcy, wavelength λ, and CD value. The relationship data between each focus position Fcy, wavelength λ, and CD value is stored in the file C in advance based on the results of optical simulation or test exposure. Figure 30 An example of file C is shown. The lithography control unit 110 reads file C stored in advance.

[0309] In step S82 , the lithography control unit 110 obtains an approximate curve (CD curve) based on the file C that indicates the relationship between the CD value and the wavelength λ at the focus position Fcy(n).

[0310] Next, in step S83, the photolithography control unit 110 determines the shortest wavelength λ in the wavelength range that exhibits a predetermined allowable CD value at the focus position Fcy(n) based on the CD curve determined in step S82. S (n) and the longest wavelength λ L (n).

[0311] After step S83, the photolithography control unit 110 ends Figure 29 Flowchart of , returns Figure 27 Flowchart of the process.

[0312] Figure 31 It shows Figure 29 Graph showing an example of a CD curve obtained in step S82. Figure 31 Show Figure 29 An example of the prescribed allowable CD value used in step S83, and the shortest wavelength λ obtained based on the allowable CD value and the CD curve S (n) and the longest wavelength λ L (n) Example. The optimal wavelength λb can be, for example, the shortest wavelength λ S (n) and the longest wavelength λ L (n) The value at the center of a specified wavelength range. Figure 31 The CD curve shown is an example of the “first approximate curve” in the present disclosure.

[0313] Figure 32 is shown to be applied to Figure 27 This is a flowchart of an example of a subroutine of step S72. Figure 32 In step S91, the photolithography control unit 110 reads a file D of the relationship between the magnification βcy and the wavelength λ. The relationship data between the magnification βcy and the wavelength λ is stored in the file D in advance based on the results of optical simulation or test exposure. Figure 33 An example of file D is shown. The lithography control unit 110 reads file D stored in advance.

[0314] Next, in step S92 , the lithography control unit 110 obtains an approximate curve F that specifies the relationship between the magnification βcy and the wavelength λ based on the file D.

[0315] Next, in step S93, the photolithography control unit 110 calculates the wavelength λ that exhibits the magnification βcy(n) using the function of the approximate curve F. M (n) When the function of the approximate curve F is λ=F{βcy}, the photolithography control unit 110 uses λ M(n) = F{βcy(n)} to calculate wavelength λ M (n).

[0316] After step S93, the photolithography control unit 110 ends Figure 32 Flowchart of , returns Figure 27 Flowchart of the process.

[0317] Figure 34 It shows Figure 32 Graph showing an example of the approximate curve F obtained in step S92. Figure 34 The function of the approximate curve F is used to determine the wavelength λ that exhibits the magnification βcy(n). M The idea of calculating (n). Wavelength λ M (n) is an example of the “first wavelength” in the present disclosure. Approximate curve F is an example of the “second approximate curve” in the present disclosure.

[0318] 5.3 Effect

[0319] According to the lithography system 100 of the first embodiment, a target wavelength λt for each pulse is calculated, which approximates the height of the pattern processed on the wafer WF and the magnification βcy. Scanning projection exposure is performed within the scanning field SF using pulsed laser light of this target wavelength λt. This allows correction of both the magnification and the focus position in a direction orthogonal to the scanning direction. Consequently, both overlay accuracy and CD accuracy are improved.

[0320] 6. Implementation Method 2

[0321] 6.1 Structure

[0322] In the first embodiment, an example was described in which wafer height Hc was measured using wafer inspection apparatus 310 and focus position Fcy was determined based on the measurement result. In contrast, in the second embodiment, focus position Fcy is measured immediately before exposure using focus sensor 58 disposed within exposure apparatus 14.

[0323] Figure 35 This diagram schematically illustrates an example of measurement points on a wafer WF by a focus sensor 58 disposed within the exposure unit 14 of a lithography system 100 according to a second embodiment. The focus sensor 58 employed in the second embodiment includes multiple autofocus (AF) sensors capable of measuring wafer height at multiple locations within the wafer WF. Each of the multiple AF sensors includes a light-emitting element and a light-receiving element.

[0324] Figure 35 The scanning field SF during exposure is shown to be scanned by the scanning beam SB, and the scanning beam SB is shown to be moving relative to the scanning field SF in the positive direction of the Y axis. Figure 35The plurality of dot marks arranged in the scanning field SF in FIG. 1 schematically represent the respective measurement points of the plurality of AF sensors not shown. Figure 35 In order to simplify the diagram, the number of measurement points is reduced, but the actual number of measurement points may be larger.

[0325] The AF sensor does not require a mark on the wafer WF when measuring the height of the wafer WF, and can perform measurement regardless of whether there is a pattern on the wafer WF. The AF sensor performs measurement in real time during scanning exposure.

[0326] Multiple AF sensors are classified into three types based on their functions. The first AF sensor is used to measure the wafer height within the area being exposed by the scanning beam SB. The second AF sensor is used to pre-read the wafer height during scanning in the positive Y-axis direction. The third AF sensor is used to pre-read the wafer height during scanning in the negative Y-axis direction. "Pre-reading" means measuring the wafer height of an unexposed area within the scanning field SF before exposure, and here, it means measuring the wafer height immediately before exposure.

[0327] Figure 36 This is a side view schematically showing an example of the structure of an AF sensor unit 580 used in the exposure apparatus 14 of the lithography system according to Embodiment 2. The exposure apparatus 14 according to Embodiment 2 includes an AF sensor unit 580 including a plurality of AF sensors as the focus sensor 58. The AF sensor unit 580 includes an AF light emitting unit 582 and an AF light receiving unit 584. The AF light emitting unit 582 and the AF light receiving unit 584 are arranged so as to be aligned in the Y-axis direction with the projection optical system 50 interposed therebetween.

[0328] The AF light emitting unit 582 includes a first AF sensor light emitting element group, a second AF sensor light emitting element group, and a third AF sensor light emitting element group. The AF light receiving unit 584 includes a first AF sensor light receiving element group, a second AF sensor light receiving element group, and a third AF sensor light receiving element group.

[0329] exist Figure 36 In FIG, the bold arrow indicates light emitted from the light emitting element of the second AF sensor that performs pre-reading in the scanning in the positive direction of the Y axis. Figure 36 In FIG, the thin arrow indicates the light emitted from the light emitting element of the first AF sensor. Figure 36 In FIG. 1 , the dotted arrow indicates light emitted from the light emitting element of the third AF sensor performing pre-reading in scanning in the negative direction of the Y axis.

[0330] 6.2 Action

[0331] 6.2.1 Example of Processing Contents of the Lithography Control Unit

[0332] Figure 37 1 is a flowchart showing an example of the processing content of the lithography control unit 110 in the lithography system 100 of the second embodiment. Figure 37 In, with Figure 12 The same steps are marked with the same step numbers and repeated explanations are omitted. Figure 37 , for Figure 12 The differences are explained.

[0333] Figure 37 The flowchart shown has been deleted Figure 12 Steps S14, S16 and S17 are performed, and after step S13, step S15 is entered, and after step S15, step S18 is entered. Figure 12 same.

[0334] In the lithography system 100 of Embodiment 2, file data for each of files A1, C, and D can be written and read in the lithography control unit 110 and the exposure control unit 40. File A1 contains table data of pulse number n and magnification βcy. File C contains table data of the relationship between each focus position Fc, wavelength λ, and CD value. File D contains table data of the relationship between wavelength λ and magnification β.

[0335] 6.2.2 Example of processing content of exposure control unit

[0336] Figure 38 This is a flowchart showing an example of the processing content of the exposure control unit 40 in the lithography system 100 of the second embodiment. The exposure control unit 40 can replace Figure 13 Execute the flowchart described in Figure 38 The process of the flowchart shown.

[0337] In step S101 , the exposure control unit 40 prepares for starting scanning exposure.

[0338] Next, in step S102 , the exposure control unit 40 sets the index n of the pulse number of the scanning exposure pulse irradiated in one scan to “1”.

[0339] Next, in step S103 , the exposure control unit 40 reads the data of the file A1 storing the pulse numbers and magnifications βcy(n) in the scanning field SF.

[0340] Next, in step S104 , the exposure control unit 40 uses the focus sensor 58 to measure the focus position in a direction perpendicular to the scanning direction immediately before exposure and calculates the focus position Fcy(n) which is the average value thereof.

[0341] Next, in step S106, the exposure control unit 40 calculates the target wavelength λt(n) of the n-th pulse in the scanning field based on the magnification βcy(n), the focus position Fcy(n) and the CD. The processing of step S106 can also be compared with Figure 27 The flowchart is the same as

[0342] Next, in step S108 , the exposure control unit 40 transmits the target wavelength λt(n) of the n-th pulse to the laser control unit 20 .

[0343] Next, in step S112 , the exposure control section 40 transmits the emission trigger signal Tr to the laser control section 20 to irradiate as the n-th pulse in the scanning field SF.

[0344] Next, in step S114 , the exposure control unit 40 determines whether the pulse number n matches the pulse number N of the last pulse irradiated in one scan.

[0345] If the result of determination in step S114 is “No”, the exposure control unit 40 proceeds to step S115 , increments the value of the index n, and returns to step S103 .

[0346] On the other hand, if the result of determination in step S114 is "YES", the exposure control unit 40 proceeds to step S116. In step S116, the exposure control unit 40 determines whether a scan field SF to be the target of the next scanning exposure exists in the wafer WF.

[0347] If the result of the determination in step S116 is "yes", the exposure control unit 40 transfers to step S118, moves the wafer WF to the next scanning field position, and then returns to step S101. On the other hand, if the result of the determination in step S116 is "no", the exposure control unit 40 ends the process. Figure 38 Flowchart of the process.

[0348] Figure 39 is shown to be applied to Figure 38 Flowchart of an example of a subroutine of step S104. In step S121, the exposure control unit 40 measures the wafer height Hc(n, m) at point M on the X axis through the focus sensor 58. Figure 35 In that case, when the scanning direction is the positive direction of the Y-axis, the chip height Hc (n, m) immediately before exposure is measured at each of the M points on the X-axis by pre-reading the AF sensor (second AF sensor) in the positive direction of the Y-axis in advance in the positive direction of the Y-axis of the exposure area of the scanning beam SB.

[0349] Next, in step S122, the exposure control unit 40 calculates the average value Havy(n) of the wafer height. The calculation formula of Havy(n) may also be the above-mentioned formula (3).

[0350] Next, in step S123 , the exposure control unit 40 obtains the focus position Fcy(n) based on the difference between the reference focus position F0 and the average value Havy(n) of the wafer height.

[0351] Next, in step S124 , the exposure control unit 40 writes the data of the focus position Fcy(n) into the file A2 .

[0352] After step S124, the exposure control unit 40 ends Figure 39 Flowchart of , returns Figure 38 Flowchart of the process.

[0353] 6.3 Effect

[0354] According to the lithography system 100 of the second embodiment, the height of the wafer WF is measured immediately before exposure, and the focus position can be controlled in real time. Therefore, the correction accuracy of the magnification and the focus position in the direction perpendicular to the scanning direction is further improved.

[0355] 7. Implementation Method 3

[0356] 7.1 Structure

[0357] Figure 40 The following schematically shows an example of the configuration of the photolithography system 103 according to the third embodiment. Figure 40 The structure shown is Figure 11 The differences are explained. Figure 40 The lithography system 103 shown is Figure 11 The structure shown in FIG. 1 is supplemented by a piezoelectric actuator 504. This piezoelectric actuator 504 selects one or more lenses 502 in the projection optical system 50 and drives these lenses 502 at high speed along the optical axis. This lens 502 can control the magnification of the entire projection optical system 50 with minimal impact on imaging performance, including wavefront aberration. This one or more lenses 502 are referred to as "magnification correction lenses 502."

[0358] The exposure control unit 40 is connected to a signal line for controlling the piezoelectric actuator 504 so as to move the magnification correction lens 502 in the optical axis direction during scanning exposure.

[0359] 7.2 Action

[0360] The lithography system 103 of the third embodiment not only corrects the magnification by the target wavelength λt but also uses the magnification correction lens 502 of the projection optical system 50 to correct the region where the focus position is shifted, i.e., the region where the focus position is not fully corrected by the target wavelength λt.

[0361] The lithography control unit 110 or the exposure control unit 40 is added with a function of controlling the position of the magnification correction lens 502 so as to reduce the magnification difference that is not completely corrected by the target wavelength λt of the laser light output from the laser device 12 .

[0362] The processing content of the lithography control unit 110 can also be Figure 37 The flowchart is the same as

[0363] Figure 41 This is a flowchart showing an example of the processing content of the exposure control unit 40 in the photolithography system 103 of the third embodiment. The exposure control unit 40 can replace Figure 38 Execute the flowchart described in Figure 41 The process is shown in the flowchart. Figure 41 In, with Figure 38 The same steps are marked with the same step numbers and repeated explanations are omitted. Figure 41 The flowchart shown is for Figure 38 The differences are explained.

[0364] Figure 41 The flowchart shown replaces Figure 38 The method includes step S106A instead of step S106, and further includes step S109 between step S108 and step S112.

[0365] exist Figure 41 In step S106A, the exposure control unit 40 calculates the target wavelength λt(n) of the n-th pulse in the scanning field SF and the control value γc(n) of the magnification correction lens 502 of the projection optical system 50 based on the magnification βcy(n), the focus position Fcy(n) and the CD.

[0366] After step S108, in step S109, the exposure control unit 40 sends the control value γc(n) to the piezoelectric actuator 504 that drives the magnification correction lens 502 of the projection optical system 50. The other steps can be the same as Figure 38 same.

[0367] Figure 42 is shown to be applied to Figure 41 A flowchart of an example of a subroutine of step S106A. Figure 42 Steps S71 to S77 in Figure 27 The flowchart is the same as Figure 42The flowchart shown is for Figure 27 The differences are explained. Figure 42 The flowchart shown replaces Figure 27 The step S78 includes step S140, step S141, step S142 and step S148.

[0368] like Figure 42 As shown, after step S75, the exposure control unit 40 proceeds to step S140. In step S140, the exposure control unit 40 sets the control value γc(n) of the magnification correction lens 502 to "0".

[0369] After step S76, the exposure control unit 40 proceeds to step S141. In step S141, the exposure control unit 40 calculates the control value γc(n) of the magnification correction lens 502 so that the difference between the magnification βcy(n) and the magnification βλt(n) at the wavelength λt(n) is close to zero.

[0370] After step S77, the exposure control unit 40 proceeds to step S142. The processing content of step S142 may be the same as that of step S141.

[0371] After step S140 , step S141 , or step S142 , the exposure control section 40 proceeds to step S148 .

[0372] In step S148, the exposure control unit 40 writes Fcy(n), λ S (n), λ L (n), βcy(n), λ M (n), λt(n) and γc(n). File B used in the third embodiment is Figure 28 The data table of file B illustrated in FIG is obtained by adding data of the control value γc(n) of the magnification correction lens 502 .

[0373] After step S148, the exposure control unit 40 ends Figure 42 Flowchart of , returns Figure 41 Flowchart of the process.

[0374] Figure 43 is shown to be applied to Figure 42 This is a flowchart of an example of a subroutine of steps S141 and S142. Figure 43 In step S161 , the exposure control unit 40 obtains the magnification βλt(n) at the target wavelength λt(n) based on the file D.

[0375] Next, in step S162 , the exposure control unit 40 calculates the difference Δβ(n) between the magnification βcy(n) and the magnification βλt(n) using the following equation (5).

[0376] Δβ(n)=βλt(n)-βcy(n) (5)

[0377] Δβ(n) obtained by equation (5) can be equivalent to the magnification correction value.

[0378] Next, in step S163, the exposure control unit 40 calculates the control value γc(n) of the magnification correction lens 502 so that Δβ(n) is close to 0. The exposure control unit 40 may store the relationship between Δβ and the control value γc of the magnification correction lens 502 in advance in a storage unit, for example, as table data or a function, and call out the table data or function to calculate the control value γc(n) of the magnification correction lens 502.

[0379] After step S163, the exposure control unit 40 ends Figure 43 Flowchart of , returns Figure 42 Flowchart of the process.

[0380] 7.3 Effect

[0381] According to the lithography system 103 of the third embodiment, the region where magnification correction cannot be performed in the structure of the first embodiment, namely, λ M (n)<λ S (n) or λ L (n)<λ M In the region (n), by controlling the magnification correction lens 502 , it is possible to approach the target magnification, and the overlay is further improved.

[0382] 7.4 Variations

[0383] In the third embodiment, the height of the wafer WF is measured by the focus sensor 58 of the exposure device 14. However, the present invention is not limited to this example. As in the first embodiment, the wafer height may be measured in advance by the wafer inspection device 310 and processed. In this case, the lithography control unit 110 may also execute the same process as described above. Figure 41 The same calculation process as step S106A described above is performed, and the data of the target wavelength λt(n) from the first pulse to the last pulse in the scanning field SF is sent to the laser control unit 20 via the exposure control unit 40. The data of the control value γc(n) of the magnification correction lens 502 is also sent to the exposure control unit 40 in advance. Alternatively, the laser control unit 20 may output laser light of the target wavelength λt(n) for each pulse, and the exposure control unit 40 may control the magnification correction lens 502 so that the control value γc(n) of the magnification correction lens 502 is obtained for each pulse.

[0384] 8. Implementation Method 4

[0385] 8.1 Structure

[0386] Figure 44 An example configuration of the photolithography system 104 according to the fourth embodiment is schematically shown. Figure 44 The structure shown is Figure 11 The differences are explained. Figure 44 The photolithography system 104 shown replaces Figure 11 The exposure control unit 40 includes the exposure control unit 40D. Figure 11 same.

[0387] The exposure control unit 40D performs the following control: Figure 11 Similarly, the exposure control unit 40 corrects the magnification by the target wavelength λt, and further controls the Z-axis stage of the wafer stage 54 in the wavelength region where the focus position is shifted, thereby changing the focus position.

[0388] 8.2 Action

[0389] The photolithography control unit 110 or the exposure control unit 40D corrects the magnification using the target wavelength λt of the laser light output from the laser device 12. In a region where the CD value deviates from the permissible range even after this correction, the exposure control unit 40D controls the Z-axis stage of the wafer stage 54 to control the focus position so that the CD value falls within the permissible range. The flowchart that can be implemented by the photolithography control unit 110 can also be compared with Figure 37 same.

[0390] Figure 45 This is a flowchart showing an example of the processing content of the exposure control unit 40D in the photolithography system 104 according to the fourth embodiment. The exposure control unit 40D can replace Figure 38 Execute the flowchart described in Figure 45 The process is shown in the flowchart. Figure 45 In, with Figure 38 The same steps as shown are marked with the same step numbers and their descriptions are omitted. Figure 45 The flowchart shown is for Figure 38 The differences are explained.

[0391] Figure 45 The flowchart shown replaces Figure 38 The method includes step S106B instead of step S106, and further includes step S110 between step S108 and step S112.

[0392] In step S106B, the exposure control unit 40D calculates the target wavelength λt(n) and focus position Fc(n) of the n-th pulse in the scanning field SF based on the magnification βcy(n), the focus position Fcy(n), and the CD. The focus position Fc(n) here corresponds to the target focus position.

[0393] After step S108, in step S110, the exposure control unit 40D controls the wafer stage 54 so that the focus position becomes Fc(n). After step S110, the exposure control unit 40D proceeds to step S112. Other steps can also be Figure 38 same.

[0394] Figure 46 is shown to be applied to Figure 45 This is a flowchart of an example of a subroutine of step S106B. Figure 46 The flowchart shown is for Figure 27 The differences are explained. Figure 46 The flowchart shown includes step S73 between step S72 and step S74. Figure 27 Steps S75 to S77 include steps S145 to S147, instead of Figure 27 step S78 and includes step S149.

[0395] exist Figure 46 After step S72, the exposure control unit 40D proceeds to step S73.

[0396] In step S73, the exposure control unit 40D sets the target wavelength λt(n) to the wavelength λ M (n) After step S73, the exposure control unit 40D proceeds to step S74.

[0397] In step S74, the result of the determination is that S (n)≤λ M (n)≤λ L In the case of (n), the exposure control unit 40D proceeds to step S145.

[0398] In step S145 , the exposure control unit 40D sets the target focus position Fc(n) as the reference focus position F0 .

[0399] In step S74, the result of the determination is M (n)<λ S (n), the exposure control unit 40D proceeds to step S146. In step S146, the exposure control unit 40D calculates the focus position Fc(n) so that the wavelength is λ M In the case of (n), the CD value is within the allowable range.

[0400] In step S74, the result of the determination is L (n)<λ M In the case of (n), the exposure control unit 40D proceeds to step S147. Step S147 may be the same as step S146.

[0401] After step S145, step S146 or step S147, the exposure control unit 40D proceeds to step S149. In step S149, the exposure control unit 40D writes Fcy(n), λ S (n), λ L (n), βcy(n), λ M (n), λt(n) and Fc(n) data.

[0402] After step S149, the exposure control unit 40D ends Figure 46 Flowchart of , returns Figure 45 Flowchart of the process.

[0403] Figure 47 is shown to be applied to Figure 46 This is a flowchart of an example of a subroutine of steps S146 and S147. Figure 47 In step S171, the exposure control unit 40D reads the file E of the relationship between the wavelength λ and the focus position Fb. Before step S171, the file E of the relationship between the wavelength λ and the focus position Fb of the projection optical system 50 is calculated or measured in advance and stored. Figure 48 An example of the file E is shown. The exposure control unit 40D reads the previously stored file E. In addition, at the focus position Fb, the CD value can be maintained within the allowable range.

[0404] Next, in step S172 , the exposure control unit 40D obtains the approximate curve G based on the file E.

[0405] Next, in step S173, the exposure control unit 40D calculates the wavelength λ using the function approximating the curve G. M When the function of the approximate curve G is set to Fb=G{λ}, the exposure control unit 40D uses Fc(n)=G{λ M (n)}Calculate the focus position.

[0406] After step S173, the exposure control unit 40D ends Figure 47 Flowchart of , returns Figure 46 Flowchart of the process.

[0407] Figure 49 It shows Figure 47 Graph showing an example of the approximate curve G obtained in step S172. The horizontal axis represents the wavelength λ, and the vertical axis represents the focus position Fb. Figure 49 The function obtained using the approximate curve G is shown as a function of wavelength λ. M The idea behind the calculation method of Fc(n) corresponding to the focus position.

[0408] 8.3 Effect

[0409] According to the lithography system 104 of the fourth embodiment, the region where magnification correction cannot be performed in the structure of the first embodiment, namely, λ M (n)<λ S (n) or λ L (n)<λ M In the region (n), the focus position is controlled to approach the target magnification, and the CD is maintained within the allowable range, thereby further improving the overlay.

[0410] 8.4 Variation 1

[0411] Figure 50 This is a flowchart showing an example of the processing content of the exposure control unit 40D according to the modification of the fourth embodiment. Figure 45 Flowchart and application Figure 50 The flowchart shown. Figure 50 The flowchart shown is for Figure 45 The differences are explained. Figure 50 The flowchart shown replaces Figure 45 The other steps may be the same as step S106B. Figure 45 same.

[0412] exist Figure 50 In step S106C, the exposure control unit 40D obtains the target wavelength λt(n) and the focus position Fc(n) of the n-th pulse in the scanning field SF based on the magnification βcy(n).

[0413] Figure 51 is shown to be applied to Figure 50 This is a flowchart of an example of a subroutine of step S106C. Figure 51 The flowchart shown is for Figure 46 The differences are explained. Figure 51 The flowchart shown is deleted Figure 46 Steps S71, S74 and S145 are performed, and after step S73, step S146 is entered. The other steps can be Figure 46 same.

[0414] 8.5 Variation 2

[0415] In the fourth embodiment, the height of the wafer WF is measured by the focus sensor 58 of the exposure device 14. However, the present invention is not limited to this example. As in the first embodiment, the wafer height may be measured in advance by the wafer inspection device 310 and processed.

[0416] That is, in the lithography control unit 110, it is also possible to execute Figure 45The calculation processing of step S106B sends the data of each target wavelength λt(n) from the first pulse to the last pulse in the scanning field SF to the laser control unit 20 via the exposure control unit 40D, and the data of the focus position Fc(n) is sent to the exposure control unit 40D in advance.

[0417] Furthermore, the laser control unit 20 may output laser light of the target wavelength λt(n) for each pulse, and the exposure control unit 40D may control the wafer stage 54 so that the wafer stage 54 is at the focus position Fc(n) for each pulse.

[0418] 9. Implementation Method 5

[0419] 9.1 Structure

[0420] Figure 52 A configuration example of the photolithography system 105 according to the fifth embodiment is schematically shown. Figure 52 The structure shown is Figure 11 The differences are explained. Figure 52 The photolithography system 105 is shown Figure 11 The structure shown in the figure is supplemented by a pulse energy sensor unit 45 for measuring the dose on the wafer surface. Figure 11 The exposure control unit 40 includes an exposure control unit 40E.

[0421] The pulse energy sensor unit 45 includes a beam splitter 451 disposed on the optical path between the illumination optical system 44 and the reticle stage 48, and a pulse energy sensor 452 that receives the pulse laser light sampled by the beam splitter 451. The pulse energy sensor 452 is connected to the exposure control unit 40E via a signal line.

[0422] 9.2 Action

[0423] The lithography control unit 110 or the exposure control unit 40E corrects the magnification using the target wavelength λt of the laser light output from the laser device 12. In areas where the CD value deviates from the allowable range even after this correction, the exposure control unit 40E controls the dose on the wafer WF surface so that the CD value remains within the allowable range.

[0424] The exposure control unit 40E transmits the target pulse energy Et to the laser control unit 20 to control the dose on the wafer WF surface for each pulse.

[0425] The flowchart that can be implemented by the lithography control unit 110 can also be Figure 37 same.

[0426] Figure 53This is a flowchart showing an example of the processing content of the exposure control unit 40E in the photolithography system 105 of the fifth embodiment. The exposure control unit 40E can replace Figure 38 Execute the flowchart described in Figure 53 The process of the flowchart shown in FIG. Figure 53 The flowchart shown is for Figure 38 The differences are explained. Figure 53 The flowchart shown replaces Figure 38 Instead of step S106 and step S108, step S106E and step S108E are included, and step S107 is included between step S106E and step S108E.

[0427] In step S106E, the exposure control unit 40E calculates the target wavelength λt(n) and target dose Dt(n) of the n-th pulse in the scanning field SF based on the magnification βcy(n), the focus position Fcy(n), and the CD.

[0428] Next, in step S107 , the exposure control unit 40E calculates the target pulse energy Et(n) of the next pulse based on the target dose Dt(n).

[0429] Then, in step S108E, the exposure control unit 40E sends the target wavelength λt(n) and target pulse energy Et(n) of the n-th pulse to the laser control unit 20. The other steps can be the same as Figure 38 same.

[0430] Figure 54 is shown to be applied to Figure 53 A flowchart of an example of a subroutine of step S106E. Figure 54 Steps S71 to S74 and Figure 46 Same. About Figure 54 The flowchart shown is for Figure 46 The differences are explained.

[0431] Figure 54 The flowchart shown replaces Figure 46 The system includes steps S145, S146, S147 and S149 and includes steps S155, S156, S157 and S159.

[0432] exist Figure 54 The result of step S74 in the above example satisfies λ S (n)≤λ M (n)≤λ L In the case of (n), the exposure control unit 40E proceeds to step S155.

[0433] In step S155 , the exposure control section 40E determines the target dose Dt(n) as the reference dose Ds.

[0434] In step S74, the result of the determination is M (n)<λ S (n), the exposure control unit 40E proceeds to step S156. In step S156, the exposure control unit 40E calculates the target dose Dt(n) so that at a wavelength of λ M In the case of (n), the CD value is within the allowable range.

[0435] In step S74, the result of the determination is L (n)<λ M In the case of (n), the exposure control unit 40E proceeds to step S157. Step S157 may be the same as step S156.

[0436] After step S155, step S156 or step S157, the exposure control unit 40E proceeds to step S159. In step S159, the exposure control unit 40E writes Fcy(n), λ S (n), λ L (n), βcy(n), λ M (n), λt(n) and Dt(n) data.

[0437] After step S159, the exposure control unit 40E ends Figure 54 Flowchart of , returns Figure 53 Flowchart of the process.

[0438] Figure 55 This is a graph showing an example of the relationship between the CD value and the dose D. The horizontal axis represents the dose D, and the vertical axis represents the CD value. Figure 55 Such a relationship curve is called a "CD-dose curve". The exposure control unit 40E is based on, for example, Figure 31 The data of file A0 described in the above is used to sort out the data on the relationship between the CD value and the dose D related to the wafers exposed in the past under the same exposure conditions as the wafer WF exposed this time, and the relationship data is saved in file F.

[0439] The exposure control unit 40E can then generate an approximate curve representing the relationship between the CD value and the dose D based on the file F, and determine the target dose Dt value for achieving the target CD value based on a function of the approximate curve (i.e., the CD-dose curve). Alternatively, the approximate curve representing the relationship between the CD value and the dose D can be calculated using exposure simulation software. Figure 55 The CD-dose curve shown is an example of the “third approximate curve” in the present disclosure.

[0440] Figure 56 is shown to be applied to Figure 53 Flowchart of an example of the subroutine of step S107. In step S181, the exposure control unit 40E calculates the target pulse energy density Ew(n) of the next pulse on the surface of the wafer WF by the following equation (6).

[0441] [Mathematical formula 2]

[0442]

[0443] Where NSL is the number of pulses irradiating the resist. Ed(k) is the energy density on the wafer for each pulse. Ed(k) is measured by a pulse energy sensor 452 located within the exposure device 14, and the data is stored in a memory unit (not shown).

[0444] Next, in step S182 , the exposure control unit 40E calculates the target pulse energy Et(n) output from the laser device 12 using the following equation (7).

[0445] Et(n)=(1 / T)Bx·By·Ew(n) (7)

[0446] Where T is the transmittance of the pulsed laser light in the exposure device 14 from the laser outlet of the laser device 12 to the wafer WF. In addition, Bx·By is the area of the static exposure area SEA of the laser beam irradiated on the wafer WF (see Figure 8 ).

[0447] After step S182, the exposure control unit 40E ends Figure 56 Flowchart of , returns Figure 53 Flowchart of the process.

[0448] 9.3 Effect

[0449] According to the lithography system 105 of the fifth embodiment, the region where magnification correction cannot be performed in the structure of the first embodiment, namely, λ M (n)<λ S (n) or λ L (n)<λ M In the region (n), the target magnification can be approached by controlling the dose, and further, the CD is maintained within the allowable range by the dose control, thereby improving the overlay and CD uniformity.

[0450] 9.4 Variations

[0451] In the fifth embodiment, the height of the wafer WF is measured by the focus sensor 58 of the exposure device 14. However, the present invention is not limited to this example. As in the first embodiment, the wafer height may be measured in advance by the wafer inspection device 310 and processed.

[0452] That is, in the lithography control unit 110, it is also possible to execute Figure 53 In the calculation processing of steps S106E and S107, data on the target wavelength λt(n) and target pulse energy Et(n) from the first pulse to the final pulse in the scanning field SF are sent in advance to the laser control unit 20 via the exposure control unit 40E. Furthermore, the laser control unit 20 may be configured to output laser light controlled to the target wavelength λt(n) and target pulse energy Et(n) for each pulse.

[0453] 9.5 Other

[0454] As described in each of the embodiments 3, 4 and 5, by performing correction control based on the magnification correction lens 502, correction control of the focus position and correction control of the dose, the CD value can be controlled to be within the allowable range. However, by combining these three correction controls separately, the magnification correction in the direction orthogonal to the scanning direction (scanning width direction) can be further improved while maintaining the CD value within the allowable range.

[0455] 10. Examples of Excimer Laser Devices Using Solid-State Laser Devices as Oscillators

[0456] 10.1 Structure

[0457] Figure 9 The laser device 12 described in the above example uses a narrowband gas laser device as the oscillator 22. However, the structure of the laser device is not limited to Figure 9 For example, you can also replace Figure 9 The laser device 12 shown is used Figure 57 The laser device 212 is shown. Figure 57 The structure shown is Figure 9 The same or similar elements are denoted by the same reference numerals, and their description is omitted.

[0458] Figure 57 The laser device 212 shown is an excimer laser device using a solid-state laser device as an oscillator, and includes a solid-state laser system 222 , an excimer amplifier 224 , and a laser control unit 220 .

[0459] The solid-state laser system 222 includes a semiconductor laser system 230 , a titanium-doped sapphire amplifier 232 , a pump pulse laser 234 , a wavelength conversion system 236 , and a solid-state laser control unit 238 .

[0460] The semiconductor laser system 230 includes a distributed feedback (DFB) semiconductor laser 250 that outputs CW laser light with a wavelength of approximately 773.6 nm, and a semiconductor optical amplifier (SOA) 260 that pulses the CW laser light. Figure 58 This will be described later.

[0461] The titanium sapphire amplifier 232 includes a titanium sapphire crystal. The titanium sapphire crystal is placed in the optical path of the pulsed laser light after pulse amplification by the SOA of the semiconductor laser system 230. The pump pulse laser 234 can also be a laser device that outputs the second harmonic light of a YLF laser. YLF (lithium yttrium fluoride) is a solid-state laser crystal represented by the chemical formula LiYF4.

[0462] Wavelength conversion system 236 includes multiple nonlinear optical crystals that convert the wavelength of incident pulsed laser light to output a fourth harmonic pulsed laser light. Wavelength conversion system 236 includes, for example, an LBO crystal and a KBBF crystal. The LBO crystal is a nonlinear optical crystal represented by the chemical formula LiB3O5. The KBBF crystal is a nonlinear optical crystal represented by the chemical formula KBe2BO3F2. Each crystal is mounted on a rotating stage (not shown) and configured to allow for varying the angle of incidence on the crystal.

[0463] The solid-state laser control unit 238 controls the semiconductor laser system 230 , the pumping pulse laser 234 , and the wavelength conversion system 236 in accordance with instructions from the laser control unit 220 .

[0464] Excimer amplifier 224 includes cavity 160, PPM 164, charger 166, convex mirror 241, and concave mirror 242. Cavity 160 includes windows 171 and 172, a pair of electrodes 173 and 174, and an electrically insulating member 175. ArF laser gas is introduced into cavity 160. PPM 164 includes switch 165 and a charging capacitor.

[0465] The excimer amplifier 224 is configured to amplify seed light having a wavelength of 193.4 nm by passing it three times through the discharge space between the pair of electrodes 173 and 174. The seed light having a wavelength of 193.4 nm is pulsed laser light output from the solid-state laser system 222.

[0466] The convex mirror 241 and the concave mirror 242 are arranged so as to expand the beam of the pulsed laser light output from the solid-state laser system 222 outside the cavity 160 in three passes.

[0467] The seed light having a wavelength of approximately 193.4 nm incident on the excimer amplifier 224 is reflected by the convex mirror 241 and the concave mirror 242, thereby passing three times through the discharge space between the pair of discharge electrodes 412 and 413. This expands and amplifies the beam of the seed light.

[0468] 10.2 Action

[0469] After receiving the target wavelength λt, target spectral line width Δλt and target pulse energy Et from the exposure control unit 40, the laser control unit 220 calculates the target wavelength λ1cht and target spectral line width Δλ1cht of the pulsed laser from the semiconductor laser system 230 that present these target values, for example based on table data or approximate formula.

[0470] The laser control unit 220 sends the target wavelength λ1cht and the target line width Δλ1cht to the solid laser control unit 238 and sets the charging voltage for the charger 166 so that the pulsed laser output from the excimer amplifier 224 has the target pulse energy Et.

[0471] The solid laser control unit 238 controls the semiconductor laser system 230 so that the pulsed laser light outputted from the semiconductor laser system 230 approaches the target wavelength λ1cht and the target line width Δλ1cht. Figures 58 to 61 This will be described later.

[0472] Furthermore, the solid-state laser control unit 238 controls two rotating stages (not shown) to achieve an incident angle at which the wavelength conversion efficiency of the LBO crystal and the KBBF crystal of the wavelength conversion system 236 is maximized.

[0473] When the light emission trigger signal Tr is transmitted from the exposure control unit 40 to the laser control unit 220, a trigger signal is input to the semiconductor laser system 230, the pump pulse laser 234, and the switch 165 of the PPM 164 of the excimer amplifier 224 in synchronization with the light emission trigger signal Tr. As a result, a pulse current is input to the SOA of the semiconductor laser system 230, and pulse laser light after pulse amplification is output from the SOA.

[0474] Pulsed laser light is output from the semiconductor laser system 230 and further pulse-amplified in the titanium-doped sapphire amplifier 232. This pulsed laser light is incident on the wavelength conversion system 236. As a result, the wavelength conversion system 236 outputs pulsed laser light having a target wavelength λt.

[0475] After receiving the light emission trigger signal Tr from the exposure control unit 40, the laser control unit 220 sends trigger signals to the later-described SOA260 of the semiconductor laser system 230, the switch 165 of the PPM164, and the pump pulse laser 234, respectively, so as to generate discharge when the pulse laser output from the solid laser system 222 is incident on the discharge space of the cavity 160 of the excimer amplifier 224.

[0476] As a result, the pulsed laser light output from the solid-state laser system 222 is amplified in three passes by the excimer amplifier 224. The pulsed laser light amplified by the excimer amplifier 224 is sampled by the beam splitter 181 of the monitor module 26, the pulse energy E is measured by the optical sensor 184, and the wavelength λ and the spectral line width Δλ are measured by the spectrum detector 183.

[0477] The laser control unit 220 can also perform correction control on the charging voltage of the charger 166, the wavelength λ1ch and the spectral line width Δλ1ch of the pulsed laser output from the semiconductor laser system 230 according to the pulse energy E, wavelength λ and spectral line width Δλ measured by the monitor module 26, so that the difference between the pulse energy E and the target pulse energy Et, the difference between the wavelength λ and the target wavelength λt, and the difference between the spectral line width Δλ and the target spectral line width Δλt are close to 0 respectively.

[0478] 10.3 Description of Semiconductor Laser Systems

[0479] 10.3.1 Structure

[0480] Figure 58 The following shows an example configuration of a semiconductor laser system 230. The semiconductor laser system 230 includes a single longitudinal mode distributed feedback semiconductor laser 250, an SOA 260, a function generator (FG) 262, a beam splitter 264, a spectrum monitor 266, and a semiconductor laser control unit 268. A distributed feedback semiconductor laser is referred to as a "DFB laser."

[0481] The DFB laser 250 outputs a CW (Continuous Wave) laser having a wavelength of approximately 773.6 nm. The oscillation wavelength of the DFB laser 250 can be changed by current control and / or temperature control.

[0482] The DFB laser 250 includes a semiconductor laser element 251, a Peltier element 252, a temperature sensor 253, a temperature control unit 254, a current control unit 256, and a function generator 257. The semiconductor laser element 251 includes a first cladding layer 271, an active layer 272, and a second cladding layer 273, and includes a grating 274 at the boundary between the active layer 272 and the second cladding layer 273.

[0483] 10.3.2 Action

[0484] The oscillation center wavelength of the DFB laser 250 can be changed by changing the set temperature T and / or the current value A of the semiconductor laser element 251 .

[0485] When the oscillation wavelength of the DFB laser 250 is chirped at high speed to control the spectral line width, the spectral line width can be controlled by rapidly changing the current value A of the current flowing through the semiconductor laser element 251 .

[0486] That is, the DC component value A1dc, the AC component variation width A1ac, and the AC component period A1 are sent from the semiconductor laser control unit 268 to the function generator 257. T By using the values of the respective parameters as current control parameters, the central wavelength λ1ch and the line width Δλ1ch of the pulsed laser light output from the semiconductor laser system 230 can be controlled at high speed.

[0487] The spectrum monitor 266 can measure the wavelength using, for example, a spectrometer or a heterodyne interferometer.

[0488] The function generator 257 outputs an electrical signal having a waveform corresponding to the current control parameter specified by the semiconductor laser control unit 268 to the current control unit 256. The current control unit 256 performs current control so that a current corresponding to the electrical signal from the function generator 257 flows through the semiconductor laser element 251. Alternatively, the function generator 257 may be provided outside the DFB laser 250. For example, the function generator 257 may be included in the semiconductor laser control unit 268.

[0489] Figure 59 This is a conceptual diagram of the spectral line width achieved by chirping. The spectral line width Δλ1ch is measured as the difference between the longest and shortest wavelengths generated by chirping.

[0490] Figure 60 Schematic diagram showing the relationship between the current flowing through the DFB laser 250, the wavelength change due to chirping, the spectrum waveform, and the light intensity. Figure 60 The graph GA shown in the lower left portion of FIG. 1 is a graph showing changes in the current value A of the current flowing through the semiconductor laser element 251 . Figure 60 Graph GB shown in the center of the lower row is a graph showing chirp generated by the current in graph GA. Figure 60 The graph GC shown in the upper section is a schematic diagram of a spectrum waveform obtained by chirping the graph GB. Figure 60The graph GD shown in the lower right portion of FIG. 1 is a graph showing changes in the light intensity of the laser light output from the semiconductor laser system 230 according to the current of the graph GA.

[0491] The current control parameters of the semiconductor laser system 230 include the following values as shown in the graph GA.

[0492] A1dc: DC component value of the current flowing through the semiconductor laser element

[0493] A1ac: The fluctuation range of the AC component of the current flowing through the semiconductor laser element (the difference between the maximum and minimum current values)

[0494] A1 T : The period of the AC component of the current flowing through the semiconductor laser element

[0495] exist Figure 60 In the example shown, a triangular wave is shown as an example of the AC component of the current control parameter, and an example is shown in which the light intensity of the CW laser light output from the DFB laser 250 fluctuates less due to fluctuations in the triangular wave current.

[0496] Here, the time width D of the amplified pulse of SOA260 is preferably TW Period A1 with AC component T The relationship satisfies the following formula (8).

[0497] D TW =n·A1 T (8)

[0498] In formula (8), n is an integer greater than or equal to 1.

[0499] By satisfying the relationship of the formula (8), in the SOA 260 , regardless of the timing of pulse amplification, changes in the spectral waveform of the amplified pulse laser light can be suppressed.

[0500] Even if the equation (8) is not satisfied, the pulse width in the SOA 260 is in the range of 10 ns to 50 ns, for example. The period A1 of the AC component of the current flowing in the semiconductor laser element 251 is T The pulse width is much shorter than that of SOA260 (the time width of the amplified pulse D TW For example, the preferred period A1 T The pulse width is 1 / 1000 or more and 1 / 10 or less, and more preferably 1 / 1000 or more and 1 / 100 or less, relative to the pulse width in the SOA 260 .

[0501] In addition, the rise time of SOA260 is preferably 2 ns or less, and more preferably 1 ns or less. Figure 61 As shown in FIG. 1 , the rise time referred to here is the time Rt required for the amplitude in the waveform of the pulse current to increase from 10% to 90% of the maximum amplitude.

[0502] 10.4 Effect

[0503] The laser device 212 using the solid-state laser system 222 as an oscillator has the following advantages compared to the case of using an excimer laser as an oscillator.

[0504] [1] The solid-state laser system 222 can control the wavelength λ and the linewidth Δλ at high speed and high precision by controlling the current value A of the DFB laser 250. Specifically, upon receiving data on the target wavelength λt and the target linewidth Δλt, the laser device 212 immediately controls the current value A of the DFB laser 250, thereby enabling high-speed control of the oscillation wavelength and the linewidth Δλ. Consequently, the wavelength λ and the linewidth Δλ of the pulsed laser light output from the laser device 212 can be varied and controlled at high speed and high precision for each pulse.

[0505] [2] Furthermore, by controlling the current value A of the DFB laser 250 to chirp it, it is possible to generate spectral waveforms of various functions different from the normal spectral waveform.

[0506] [3] Therefore, when controlling the wavelength and spectral line width obtained from the spectral waveform of the moving cumulative value of the spectral waveform as laser control parameters, a laser device having an oscillator and an excimer amplifier 224 is preferred, wherein the oscillator uses a solid laser system 222 including a DFB laser 250.

[0507] 10.5 Variations

[0508] exist Figure 60 In the example shown, a triangular wave is used as an example of the waveform of the AC component of the current. However, this is not limiting; any waveform that changes with a constant period may be used. As an example other than a triangular wave, the AC component waveform may also be a sine wave, a rectangular wave, or the like. By controlling the waveform of this AC component, various target spectral waveforms can be generated.

[0509] 10.6 Others

[0510] The embodiment of the solid-state laser device is not limited to Figures 57 to 61The example shown may also include a solid-state laser system comprising a DFB laser with a wavelength of approximately 1547.2nm and an SOA, where the wavelength conversion system is a laser device that outputs 193.4nm light, an eighth harmonic. Alternatively, a system comprising a CW oscillating DFB laser and an SOA may be used, where the current flowing through the DFB laser is controlled and a pulse current flows through the SOA, thereby performing pulse amplification of the wavelength.

[0511] exist Figure 57 In the example, a multi-pass amplifier is shown as an excimer amplifier, but the present invention is not limited to this embodiment. For example, an amplifier having an optical resonator such as a Fabry-Perot resonator or a ring resonator may also be used.

[0512] 11. Hardware structure of various control units

[0513] The control device that functions as the laser control unit 20, exposure control unit 40, lithography control unit 110, solid-state laser control unit 238, semiconductor laser control unit 268, and other control units can be implemented by a combination of hardware and software of one or more computers. Software is synonymous with program. A programmable controller is included in the concept of a computer. A computer can be configured to include a CPU (Central Processing Unit) and a storage device such as a memory. A CPU is an example of a processor.

[0514] A storage device is a tangible, non-transitory computer-readable medium, including, for example, a memory as a primary storage device and a memory as a secondary storage device. Computer-readable media may be, for example, a semiconductor memory, a hard disk drive (HDD), a solid-state drive (SSD), or a combination thereof. The program executed by the processor is stored in the computer-readable medium.

[0515] Furthermore, part or all of the processing functions of the control device may be realized using an integrated circuit such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0516] In addition, a single control device can also perform the functions of multiple control devices. Furthermore, in the present disclosure, the control devices can also be connected to each other via a communication network such as a local area network or the Internet. In a distributed computing environment, the program unit can also be stored in both local and remote memory storage devices.

[0517] 12. Method for manufacturing electronic devices

[0518] Figure 62 An example configuration of the exposure device 14 is schematically shown. The exposure device 14 includes an illumination optical system 44 and a projection optical system 50. The illumination optical system 44 illuminates the reticle pattern of a reticle 46 placed on a reticle stage 48 (not shown) using laser light incident from the laser device 12. The projection optical system 50 reduces and projects the laser light transmitted through the reticle 46, forming an image on a workpiece (not shown) placed on a workpiece stage WT. The workpiece may be a photosensitive substrate such as a semiconductor wafer coated with a resist. The workpiece stage WT may be a wafer stage 54.

[0519] Exposure device 14 synchronously moves reticle stage 48 and workpiece stage WT in parallel, exposing the workpiece to laser light reflecting the reticle pattern. After the reticle pattern is transferred to a semiconductor wafer through this exposure process, semiconductor devices can be manufactured through multiple steps. Semiconductor devices are an example of "electronic devices" in this disclosure.

[0520] Figure 62 The laser device 12 may include Figure 57 The laser device 212 of the solid-state laser system 222 described in , etc.

[0521] 13. Others

[0522] The above description is not limiting but merely illustrative. Therefore, those skilled in the art will appreciate that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. Furthermore, those skilled in the art will appreciate that combinations of the embodiments of the present disclosure can be used.

[0523] Unless otherwise expressly stated, the terms used in this specification and claims as a whole should be interpreted as “non-limiting” terms. For example, terms such as “including”, “having”, “having”, and “equipped” should be interpreted as “excluding the presence of structural elements other than the structural elements to be recorded”. In addition, the modifier “one” should be interpreted as meaning “at least one” or “one or more”. In addition, terms such as “at least one of A, B, and C” should be interpreted as “A”, “B”, “C”, “A+B”, “A+C”, “B+C”, or “A+B+C”. Furthermore, it should be interpreted as also including combinations of these and parts other than “A”, “B”, and “C”.

Claims

1. A method for manufacturing an electronic device, comprising the steps of scanning and exposing a pulsed laser on a wafer in an exposure device, wherein: The method for manufacturing the electronic device comprises the following steps: determining a magnification factor as a distortion component in a scanning width direction perpendicular to a scanning direction based on a pattern formed on the wafer within a scanning field of the wafer; measuring the wafer height at multiple points within the scanning field of the wafer, and obtaining an average value of the wafer height in the scanning width direction within the scanning field based on the wafer height measurement results; determining a wavelength range of the pulsed laser light that exhibits an allowable critical dimension (CD) value at a focus position based on an average value of the wafer height; determining a first wavelength of the pulsed laser light exhibiting the magnification; Determining a target wavelength of the pulsed laser according to the wavelength range and the first wavelength; generating the pulsed laser light by a laser device so that the wavelength of each pulse becomes the target wavelength, and outputting the pulsed laser light to the exposure device; as well as The pulsed laser is exposed to the scan field of the wafer.

2. The method for manufacturing an electronic device according to claim 1, wherein: Assuming the shortest wavelength in the wavelength range is λ S , the longest wavelength is λ L The first wavelength is λ M When the target wavelength is λt, the target wavelength is determined as follows: If λ S ≤λ M ≤λ L , then λt=λ M , If λ M <λ S , then λt=λ S , If λ L <λ M , then λt=λ L .

3. The method for manufacturing an electronic device according to claim 1, wherein: The wavelength range is determined based on a first approximate curve indicating the relationship between the CD value and the wavelength of the pulsed laser light.

4. The method for manufacturing an electronic device according to claim 1, wherein: The first wavelength is determined based on a second approximate curve representing the relationship between the magnification and the wavelength of the pulsed laser light.

5. The method for manufacturing an electronic device according to claim 1, wherein: The wafer height is measured using a wafer inspection device.

6. The method for manufacturing an electronic device according to claim 1, wherein: The average value of the wafer height is determined for each pulse number indicating the order of irradiation of each pulse of the pulsed laser light irradiated within the scanning field.

7. The method for manufacturing an electronic device according to claim 1, wherein: The focus position based on the average value of the wafer height is obtained by subtracting the average value of the wafer height from a reference focus position.

8. A method for manufacturing an electronic device, comprising the steps of scanning and exposing a pulsed laser on a wafer in an exposure device, wherein: The method for manufacturing the electronic device comprises the following steps: determining a magnification factor as a distortion component in a scanning width direction perpendicular to a scanning direction based on a pattern formed on the wafer within a scanning field of the wafer; measuring focus positions at multiple points within the scanning field of the wafer, and obtaining an average value of the focus positions in the scanning width direction within the scanning field based on the focus position measurement results; Calculating a wavelength range of the pulsed laser light that exhibits an allowable critical dimension (CD) value at an average value of the focus position; determining a first wavelength of the pulsed laser light exhibiting the magnification; Determining a target wavelength of the pulsed laser according to the wavelength range and the first wavelength; generating pulsed laser light by a laser device so that the wavelength of each pulse becomes the target wavelength, and outputting the pulsed laser light to the exposure device; as well as The pulsed laser is exposed to the scan field of the wafer.

9. The method for manufacturing an electronic device according to claim 8, wherein: Assuming the shortest wavelength in the wavelength range is λ S , the longest wavelength is λ L The first wavelength is λ M When the target wavelength is λt, the target wavelength is determined as follows: If λ S ≤λ M ≤λ L , then λt=λ M , If λ M <λ S , then λt=λ S , If λ L <λ M , then λt=λ L .

10. The method for manufacturing an electronic device according to claim 9, wherein: The exposure device includes a projection optical system, a part of the lenses of the projection optical system are used as magnification correction lenses, The method for manufacturing the electronic device further comprises the following steps: In λ M <λ S In the case of M and λ S The difference between the control value of the magnification correction lens is close to 0; In λ L <λ M In the case of M and λ L The difference between the control value of the magnification correction lens and the control value of the magnification correction lens is close to 0; as well as The magnification correction lens is controlled according to the control value of the magnification correction lens.

11. The method for manufacturing an electronic device according to claim 8, wherein: Assuming the shortest wavelength in the wavelength range is λ S , the longest wavelength is λ L The first wavelength is λ M , when the target wavelength is λt, Assume that the target wavelength λt is λ M , The method for manufacturing the electronic device further comprises the following steps: If λ M <λ S or λ L <λ M , then find the target focus position where the CD value is within the allowable range; and The wafer stage of the exposure device is controlled according to the obtained target focus position.

12. The method for manufacturing an electronic device according to claim 8, wherein: Assuming the shortest wavelength in the wavelength range is λ S , the longest wavelength is λ L The first wavelength is λ M , when the target wavelength is λt, Assume that the target wavelength λt is λ M , The method for manufacturing the electronic device further comprises the following steps: If λ M <λ S or λ L <λ M , then find the target dose with CD value within the allowable range; as well as The pulse energy of the pulse laser is controlled according to the target dose.

13. The method for manufacturing an electronic device according to claim 12, wherein: The exposure apparatus includes a pulse energy sensor unit for measuring a dose on the surface of the wafer.

14. The method for manufacturing an electronic device according to claim 13, wherein: The exposure device comprises: a reticle stage; and an illumination optical system for irradiating the reticle on the reticle stage with the pulse laser light, The pulse energy sensor unit includes a beam splitter and a pulse energy sensor. The beam splitter is arranged on an optical path between the illumination optical system and the reticle.

15. The method for manufacturing an electronic device according to claim 13, wherein: The target dose is determined based on a third approximate curve representing the relationship between the CD value and the dose.

16. The method for manufacturing an electronic device according to claim 8, wherein: The exposure device includes a focus sensor that measures focus positions at multiple points within the scanning field of the wafer. The focus position is measured by the focus sensor.

17. The method for manufacturing an electronic device according to claim 16, wherein: The focus sensor includes a pre-read auto focus sensor that measures focus positions at multiple points in an unexposed area in the scanning field prior to the exposure using the pulsed laser.

18. A method for manufacturing an electronic device, comprising the steps of scanning and exposing a pulsed laser on a wafer in an exposure device, wherein: The method for manufacturing the electronic device comprises the following steps: determining a magnification factor as a distortion component in a scanning width direction perpendicular to a scanning direction based on a pattern formed on the wafer within a scanning field of the wafer; measuring focus positions at multiple points within the scanning field of the wafer, and obtaining an average value of the focus positions in the scanning width direction within the scanning field based on the focus position measurement results; determining a first wavelength of the pulsed laser light exhibiting the magnification; Setting the target wavelength of the pulsed laser to the first wavelength; determining a target focus position at which a critical dimension (CD) value is within an allowable range when the wavelength of the pulsed laser is the first wavelength; controlling the wafer stage of the exposure device according to the obtained target focus position; generating pulsed laser light by a laser device so that the wavelength of each pulse becomes the target wavelength, and outputting the pulsed laser light to the exposure device; as well as The pulsed laser is exposed to the scan field of the wafer.

19. The method for manufacturing an electronic device according to claim 18, wherein: The exposure device includes a focus sensor that measures focus positions at multiple points within the scanning field of the wafer. The focus position is measured by the focus sensor.

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