Exposure system, method for generating laser control parameters, and method for manufacturing electronic devices

Abstract

An exposure system of one aspect of the present disclosure has: a laser device that outputs pulsed laser light; an illumination optical system that guides the pulsed laser light to a reticle; a reticle stage that moves the reticle; and a processor that controls the output of the pulsed laser light from the laser device and the movement of the reticle based on the reticle stage, the exposure system irradiating the pulsed laser light to the reticle to perform a scan exposure to a semiconductor substrate. The reticle has a first region and a second region, and the processor instructs the laser device to output the pulsed laser light corresponding to each of the first region and the second region with a value of a control parameter of the pulsed laser light corresponding to each region so that the output is the pulsed laser light with a proximity effect characteristic that converges on a proximity effect characteristic within an allowable range from a difference in the proximity effect characteristic in each region from a reference.

Description

Technical Field

[0001] This disclosure relates to an exposure system, a method for generating laser control parameters, and a method for manufacturing electronic devices. Background Technology

[0002] In recent years, with the miniaturization and high integration of semiconductor integrated circuits, there has been a demand for higher resolution in semiconductor exposure equipment. Therefore, the use of shorter wavelengths of light emitted from exposure light sources has been developed. For example, as gas laser devices for exposure, KrF excimer lasers using lasers with an output wavelength of approximately 248 nm and ArF excimer lasers using lasers with an output wavelength of approximately 193 nm are examples.

[0003] The natural oscillating light from KrF and ArF excimer lasers has a relatively wide spectral linewidth, approximately 350–400 pm. Therefore, when using projection lenses made of materials that allow ultraviolet light to pass through KrF and ArF lasers, chromatic aberration sometimes occurs. As a result, resolution may be reduced. Therefore, it is necessary to narrow the spectral linewidth of the laser output from the gas laser device to a level that eliminates chromatic aberration. Thus, in the laser resonator of a gas laser device, a line-narrow module (LNM) containing narrowing elements (etalon, grating, etc.) is sometimes included to narrow the spectral linewidth. Hereinafter, gas laser devices with narrowed spectral linewidths will be referred to as narrow-bandgap gas laser devices.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: U.S. Patent Application Publication No. 2015 / 0070673

[0007] Patent Document 2: U.S. Patent Application Publication No. 2011 / 0205512

[0008] Patent Document 3: U.S. Patent Application Publication No. 2006 / 0035160

[0009] Patent Document 4: U.S. Patent Application Publication No. 2003 / 0227607

[0010] Patent Document 5: U.S. Patent Application Publication No. 2018 / 0196347

[0011] Patent Document 6: U.S. Patent Application Publication No. 2019 / 0245321

[0012] Patent Document 7: U.S. Patent Application Publication No. 2004 / 0012844 Summary of the Invention

[0013] One aspect of this disclosure discloses an exposure system for scanning exposure of a semiconductor substrate by irradiating a mask with a pulsed laser. The exposure system comprises: a laser device that outputs a pulsed laser; an illumination optics system that guides the pulsed laser to the mask; a mask stage that moves the mask; and a processor that controls the output of the pulsed laser from the laser device and the movement of the mask based on the mask stage. The mask has a first region and a second region. The processor instructs the laser device, based on the proximity effect characteristics corresponding to each of the first and second regions, on values ​​of control parameters for the pulsed laser corresponding to each region, so that its output exhibits a proximity effect characteristic in each region where the difference between the proximity effect characteristics and a reference value converges to an acceptable range.

[0014] Another aspect of this disclosure involves a method for generating laser control parameters executed by a processor. The laser control parameters are control parameters for pulsed lasers irradiating a mask of an exposure system that scans and exposes a semiconductor substrate. The method for generating the laser control parameters includes the following steps: the processor calculates proximity effect characteristics corresponding to each region of a first region and a second region of the mask; based on the calculation results, the processor determines the value of the control parameter for the pulsed laser whose proximity effect characteristics in each region converge to an acceptable range from the reference proximity effect characteristics; and the processor associates the determined control parameter value with the corresponding region and saves it in a file.

[0015] Another aspect of this disclosure discloses a method for manufacturing an electronic device comprising the steps of: scanning and exposing a photosensitive substrate by irradiating a photomask with a pulsed laser using an exposure system to manufacture the electronic device. The exposure system comprises: a laser device that outputs a pulsed laser; an illumination optics system that guides the pulsed laser to the photomask; a photomask stage that moves the photomask; and a processor that controls the output of the pulsed laser from the laser device and the movement of the photomask based on the photomask stage. The photomask has a first region and a second region. The processor instructs the laser device, based on the proximity effect characteristics corresponding to each of the first and second regions, to output a pulsed laser with proximity effect characteristics such that the difference between the proximity effect characteristics and a reference in each region converges to an allowable range. Attached Figure Description

[0016] Hereinafter, several embodiments of the present disclosure will be described as simple examples with reference to the accompanying drawings.

[0017] Figure 1 An example of an OPE (Optical Proximity Effect) curve is shown.

[0018] Figure 2 The structure of the exposure system of the comparative example is shown in general.

[0019] Figure 3 An example of the output mode of the emission trigger signal sent from the exposure control unit to the laser control unit is shown.

[0020] Figure 4 This shows an example of an exposure pattern for step-scan exposure on a wafer.

[0021] Figure 5 This shows the relationship between a scan field on the wafer and the static exposure area.

[0022] Figure 6 This is an explanatory diagram of the static exposure area.

[0023] Figure 7 This is a schematic diagram illustrating the scanning area of ​​a wafer during OPE calibration.

[0024] Figure 8 This is a flowchart illustrating an example of the sequence of OPE correction.

[0025] Figure 9 This is a graph showing an example of a reference OPE curve obtained by measuring the exposure results of a reference exposure device and an OPE curve obtained by measuring the exposure results of an exposure device to be matched.

[0026] Figure 10 This is a schematic diagram that roughly shows an example of the patterns in each scanning field of the wafer.

[0027] Figure 11 Examples of OPE curves for the first and second regions in a given scan field are shown.

[0028] Figure 12 An example of the structure of the photolithography system of Embodiment 1 is shown.

[0029] Figure 13 An example of the structure of a laser device is shown.

[0030] Figure 14 This is a flowchart illustrating an example of the processing performed by the lithography control unit in Embodiment 1.

[0031] Figure 15 This is a diagram showing an example of data written to file A.

[0032] Figure 16 This is a flowchart illustrating an example of the processing performed by the exposure control unit in Embodiment 1.

[0033] Figure 17 This is a flowchart illustrating an example of the processing performed by the laser control unit in Embodiment 1.

[0034] Figure 18An example of the structure of the photolithography system of Embodiment 2 is shown.

[0035] Figure 19 This is a flowchart illustrating an example of the processing in the lithography control unit of Embodiment 2.

[0036] Figure 20 Examples of OPE curves for each set of control parameters of the laser in a partial region Area(k) are shown.

[0037] Figure 21 An example of the structure of the photolithography system of Embodiment 3 is shown.

[0038] Figure 22 This is a flowchart illustrating an example of the processing performed by the laser control unit in Embodiment 3.

[0039] Figure 23 It shows that it is applied to Figure 22 The flowchart shows an example of the processing content of step S31a.

[0040] Figure 24 Showing through Figure 23 The calculation steps shown are examples of the spectral waveforms obtained.

[0041] Figure 25 This is a diagram showing an example of data written to file B.

[0042] Figure 26 Another structural example of a laser device is shown.

[0043] Figure 27 An example of the structure of a semiconductor laser system is shown.

[0044] Figure 28 This is a conceptual diagram of spectral linewidth achieved through chirping.

[0045] Figure 29 This is a schematic diagram illustrating the relationship between the current flowing through a semiconductor laser, the chirp-based wavelength variation, the spectral waveform, and the light intensity.

[0046] Figure 30 It is a graph used to illustrate the rise time of a semiconductor optical amplifier.

[0047] Figure 31 A structural example of an exposure apparatus is shown in general. Detailed Implementation

[0048] -Table of contents-

[0049] 1. Explanation of terminology

[0050] 2. Overview of the comparative exposure system

[0051] 2.1 Structure

[0052] 2.2 Actions

[0053] 2.3 Examples of exposure operations on wafers

[0054] 2.4 Relationship between scanning field and static exposure area

[0055] 2.5 General Procedure for OPE Calibration

[0056] 2.6 Research Topic

[0057] 3. Implementation Method 1

[0058] 3.1 Overview of the photolithography system

[0059] 3.1.1 Structure

[0060] 3.1.2 Actions

[0061] 3.2 Examples of Laser Devices

[0062] 3.2.1 Structure

[0063] 3.2.2 Actions

[0064] 3.2.3 Other

[0065] 3.4 Examples of processing content in the lithography control unit

[0066] 3.5 Examples of processing content in the exposure control department

[0067] 3.6 Examples of processing content in the laser control unit

[0068] 3.7 Function / Effect

[0069] 3.8 Other

[0070] 4. Implementation Method 2

[0071] 4.1 Structure

[0072] 4.2 Actions

[0073] 4.3 Functions / Effects

[0074] 4.4 Other

[0075] 5. Implementation Method 3

[0076] 5.1 Structure

[0077] 5.2 Actions

[0078] 5.3 Examples of processing content in the laser control unit

[0079] 5.4 Data Example for File B

[0080] 5.5 Functions / Effects

[0081] 5.6 Other

[0082] 6. Examples of excimer laser devices using solid-state laser devices as oscillators

[0083] 6.1 Structure

[0084] 6.2 Actions

[0085] 6.3 Description of Semiconductor Laser Systems

[0086] 6.3.1 Structure

[0087] 6.3.2 Actions

[0088] 6.3.3 Other

[0089] 6.4 Functions / Effects

[0090] 6.5 Other

[0091] 7. Hardware structure of various control units

[0092] 8. Manufacturing methods for electronic devices

[0093] 9. Other

[0094] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. The embodiments described below illustrate several examples of this disclosure and do not limit its scope. Furthermore, the structures and operations described in each embodiment are not necessarily all necessary for the structures and operations of this disclosure. Additionally, the same reference numerals are used to denote the same structural elements, and repeated descriptions are omitted.

[0095] 1. Explanation of terminology

[0096] The terms used in this disclosure are defined as follows.

[0097] Critical Dimension (CD) refers to the size of a fine pattern formed on a wafer such as a semiconductor. In photolithography, the CD value of a pattern varies not only due to the size of the pattern itself but also due to the influence of surrounding patterns. Therefore, for example, the CD after exposure differs depending on whether a pattern is isolated on a photomask or when it is surrounded by other patterns. The degree of variation depends not only on the distance, density, and type of adjacent patterns but also on the settings of the optical system of the exposure machine used. This optical proximity effect is called the Optical Proximity Effect (OPE). Additionally, although not an optical proximity effect, a proximity effect also exists in processes such as development during the photolithography process.

[0098] An OPE curve is a graph that plots the pattern type on the horizontal axis and the CD value or the difference between the CD value and the target CD value on the vertical axis. OPE curves are also known as OPE characteristic curves. Figure 1 An example of an OPE curve is shown. Figure 1 The horizontal axis represents the channel spacing, and the vertical axis represents the CD value. Channel spacing is an example of a pattern.

[0099] OPC (Optical Proximity Correction) refers to the process of adding bias and auxiliary patterns to the mask pattern based on exposure experimental data, given that the CD value varies according to OPE. This allows the CD value on the exposed wafer to become the target value. Generally, OPC is performed during the process development phase of the device manufacturer.

[0100] As a type of correction distinct from OPC, there is also OPE correction. OPE is also affected by the settings of the optical system used in exposure, such as the number of lens apertures (NA), illumination σ, and ring zone ratio. Therefore, by adjusting the optical system parameters of the exposure apparatus, adjustments can be made to make the CD value the target. This is called OPE correction. Both OPC and OPE correction can control the CD value. OPC is mostly performed during the process development stage, which includes mask fabrication, while OPE correction is mostly performed after mask fabrication, either immediately before or during mass production. In addition, although not an optical proximity effect, a proximity effect, represented by the micro loading effect, also exists in development, etc. Depending on the situation, sometimes it is combined with the optical proximity effect to make the CD consistent through adjustments to the optical system.

[0101] Superposition refers to the overlap of fine patterns formed on wafers such as semiconductors.

[0102] Spectral linewidth Δλ is an indicator value of the spectral width that affects exposure performance. For example, spectral linewidth Δλ can also be the bandwidth where the integrated energy of the laser spectrum reaches 95%.

[0103] 2. Overview of the comparative exposure system

[0104] 2.1 Structure

[0105] Figure 2 The structure of the comparative example exposure system 10 is schematically shown. The comparative examples disclosed herein are embodiments known only to the applicant and are not publicly known embodiments acknowledged by the applicant. The exposure system 10 includes a laser device 12 and an exposure device 14. The laser device 12 is a wavelength-variable narrowband oscillating ArF laser device, including a laser control unit 20, a laser cavity (not shown), and a narrowband module.

[0106] The exposure apparatus 14 includes an exposure control unit 40, a beam transmission unit (BDU) 42, a high reflectivity mirror 43, an illumination optics system 44, a mask 46, a mask stage 48, a projection optics system 50, a wafer holder 52, a wafer stage 54, and a focus sensor 58.

[0107] The wafer WF is held in wafer holder 52. Illumination optics system 44 is an optical system that guides a pulsed laser beam to mask 46. Illumination optics system 44 shapes the laser beam into a scanning beam with a generally rectangular intensity distribution that is homogenized. Furthermore, illumination optics system 44 controls the incident angle of the laser beam onto mask 46. Projection optics system 50 images the mask pattern onto the wafer WF. Focus sensor 58 measures the height of the wafer surface.

[0108] The exposure control unit 40 is connected to the mask stage 48, the wafer stage 54, and the focus sensor 58. Furthermore, the exposure control unit 40 is connected to the laser control unit 20. Both the exposure control unit 40 and the laser control unit 20 are configured using processors (not shown) and include storage devices such as memory. The storage devices may also be integrated into the processors.

[0109] 2.2 Actions

[0110] The exposure control unit 40 controls the movement of the wafer stage 54 in the Z-axis direction based on the height of the wafer WF measured by the focus sensor 58, so as to correct the focus position in the wafer height direction (Z-axis direction).

[0111] The exposure control unit 40 sends the target laser control parameters to the laser control unit 20 in a step-scan manner, while simultaneously sending a emission trigger signal Tr and controlling the mask stage 48 and wafer stage 54 to scan and expose the image of the mask 46 on the wafer WF. The target laser control parameters include, for example, the target wavelength λt and the target pulse energy Et. Furthermore, the term "target laser" implies "target pulsed laser." "Pulsed laser" is sometimes simply referred to as "laser."

[0112] The laser control unit 20 controls the selected wavelength of the narrowband module to make the wavelength λ of the pulsed laser output from the laser device 12 the target wavelength λt, and controls the excitation intensity to make the pulse energy E the target pulse energy Et, and outputs the pulsed laser according to the emission trigger signal Tr. Furthermore, the laser control unit 20 sends various measurement data of the pulsed laser output according to the emission trigger signal Tr to the exposure control unit 40. These measurement data include, for example, wavelength λ and pulse energy E.

[0113] 2.3 Examples of exposure operations on wafers

[0114] Figure 3 An example of the output mode of the emission trigger signal Tr sent from the exposure control unit 40 to the laser control unit 20 is shown. Figure 3 In the example shown, after adjusting the oscillation according to each wafer WF, the actual exposure mode is entered. That is, the laser device 12 initially performs adjustment oscillation, and after a predetermined time interval, performs a burst operation for the exposure of the first wafer (wafer #1).

[0115] Adjustment oscillation refers to the oscillation of a pulsed laser output for adjustment, although the pulsed laser does not directly irradiate the wafer (WF). Adjustment oscillation is performed under specified conditions until the laser stabilizes at an exposure-ready state; this adjustment oscillation is implemented before each batch of wafer production. The pulsed laser Lp is output at a specified frequency, for example, in the range of several hundred Hz to several kHz. During wafer exposure, burst operations are generally performed during repeated bursts and oscillation pauses. Burst operations are also performed during adjustment oscillation.

[0116] exist Figure 3 In this context, the pulse-dense region refers to the burst period during which pulsed laser light is continuously output for a specified period. Furthermore, in... Figure 3 In this process, the intervals where no pulses are present are the oscillation rest periods. Furthermore, during the adjustment oscillation, the length of each continuous output period of the pulse does not need to be constant; for adjustment purposes, the lengths of each continuous output period can be made different to achieve continuous output operation. After the adjustment oscillation is performed, the first wafer (wafer #1) is exposed in the exposure apparatus 14 after a relatively large time interval.

[0117] The laser device 12 oscillates and pauses during the stepping of exposure in the stepping scanning mode, and outputs pulsed laser at intervals according to the emission trigger signal Tr during scanning. This laser oscillation mode is called the burst oscillation mode.

[0118] Figure 4 An example of an exposure mode for step scan exposure on a wafer WF is shown. Figure 4 The multiple rectangular regions shown within the wafer's WF (Warrant Field) are the scanning fields (SF). The scanning field (SF) is the exposure area for a single scan exposure, also known as the scan area. For example... Figure 4 As shown, the wafer WF is divided into multiple exposure areas (scanning fields) of a specified size. During the period between the start (wafer start) and the end (wafer end) of wafer exposure, each exposure area is scanned and exposed, thereby performing wafer exposure.

[0119] That is, in wafer exposure, the following steps are repeatedly performed: a first scan exposure (scan #1) exposes a first predetermined exposure area of ​​the wafer WF, followed by a second scan exposure (scan #2) exposes a second predetermined exposure area. During one scan exposure, multiple pulsed lasers Lp (pulse #1, pulse #2, ...) can be continuously output from the laser device 12. After the scan exposure of the first predetermined exposure area (scan #1) is completed, the scan exposure of the second predetermined exposure area (scan #2) is performed at predetermined time intervals. This scan exposure is repeated sequentially. After the scan exposure of all exposure areas of the first wafer WF is completed, an adjustment oscillation is performed again, and then the wafer exposure of the second wafer WF (wafer #2) is performed.

[0120] according to Figure 4 The step scan exposure is performed in the order of the dashed arrows shown, until the wafer starts → scan #1 → scan #2 → ... → scan #126 → wafer ends. The wafer WF is an example of the "semiconductor substrate" and "photosensitive substrate" in this disclosure.

[0121] 2.4 Relationship between scanning field and static exposure area

[0122] Figure 5The relationship between a scanning field SF and a static exposure area SEA on the wafer WF is shown. The static exposure area SEA is a roughly rectangular area with a roughly uniform light intensity distribution, used for scanning exposure of the scanning field SF. A roughly rectangular, roughly uniform scanning beam, shaped by the illumination optics system 44, is irradiated onto the mask 46. Along the minor axis of the scanning beam (here, the Y-axis), the mask 46 and the wafer WF move in different orientations in the Y-axis direction according to the reduction ratio of the projection optics system 50, while being exposed. Thus, the mask pattern is scanned and exposed in each scanning field SF on the wafer WF. The static exposure area SEA can also be understood as a uniformly exposed area based on the scanning beam.

[0123] exist Figure 5 In this context, the direction towards the negative side of the vertically upward Y-axis is the scanning direction, and the direction towards the positive side of the Y-axis is the wafer movement direction. This will be compared with... Figure 5 The direction parallel to the paper plane and orthogonal to the Y-axis (X-axis direction) is called the scan width direction. Regarding the dimensions of the scan field SF on the wafer WF, for example, it is 33mm in the Y-axis direction and 26mm in the X-axis direction.

[0124] Figure 6 This is an explanatory diagram of the static exposure area (SEA). When the length of the SEA along the X-axis is Bx and its width along the Y-axis is By, Bx corresponds to the dimension of the scan field SF along the X-axis, and By is much smaller than the dimension of the scan field SF along the Y-axis. The width By along the Y-axis of the SEA is called the N-gap. The number of pulses N exposed at the resist area on the wafer WF is... SL It becomes the following formula.

[0125] N SL =(By / Vy)·f

[0126] Vy: Scanning speed of the wafer along the Y-axis

[0127] f: Laser repetition frequency (Hz)

[0128] Furthermore, the scanning beam illuminated on the mask 46 becomes a scanning beam of a size on the wafer WF that corresponds to the magnification of the projection optics system 50 of the exposure apparatus 14. For example, when the magnification of the projection optics system 50 is 1 / 4, the scanning beam illuminated on the mask 46 becomes a scanning beam of 1 / 4 the size on the wafer WF. Additionally, the scanning field region on the mask 46 becomes 1 / 4 of its scanning field SF on the wafer WF. The Y-axis beam width (By width) of the scanning beam illuminated on the mask 46 is the beam width By that realizes the Y-axis width of the static exposure area SEA on the wafer WF.

[0129] 2.5 General Procedure for OPE Calibration

[0130] OPE correction is the process of obtaining the OPE curve of a specific exposure apparatus (the reference OPE curve) as a benchmark, and adjusting the exposure conditions of other exposure apparatuses to make their OPE curves approximate the reference OPE curve. OPE correction is performed to correct for machine variations (individual differences) in exposure apparatuses. The specific exposure apparatus that serves as the benchmark is called the "reference exposure apparatus." The reference exposure apparatus is, for example, the exposure apparatus used during device development. Other exposure apparatuses are, for example, the exposure apparatuses used during mass production, and are the apparatuses to be adjusted to match the reference OPE curve. Sometimes, "other exposure apparatuses" are referred to as "the exposure apparatus to be matched."

[0131] Figure 7 This is a schematic plan view showing the scanning fields SF of the wafer WF and the patterned regions within the scanning fields SF. Multiple scanning fields SF exist within the wafer WF. When performing OPE correction, the CD of all object patterns within each scanning field SF is generally measured. In most cases, for the multiple scanning fields SF within the wafer WF, the CD related to all object patterns present in the patterned region PA of each scanning field SF is measured, obtaining an OPE curve representing the relationship between the pattern and the CD (OPE characteristics). Then, the OPE curves obtained from each scanning field SF are averaged to obtain an average OPE curve. The settings of the exposure apparatus 14 are adjusted to make the average OPE curve obtained thus close to a reference OPE curve.

[0132] Figure 8 This is a flowchart illustrating an example of the OPE correction sequence. For example, a processor of an information processing device (not shown) that manages the parameters of the exposure apparatus 14 executes a program, thereby achieving... Figure 8 Some or all of the steps shown.

[0133] In step S1, the information processing device measures the CD of all object patterns within a scan field SF exposed under reference exposure conditions using a reference exposure apparatus. Furthermore, the information processing device measures the CD in multiple scan fields SF as needed and performs averaging. Alternatively, a wafer inspection apparatus (not shown) can be used for CD measurement. By performing the processing in step S1, a reference OPE curve is obtained.

[0134] Next, in step S2, the information processing device sets the exposure device 14 to be matched to the same exposure conditions as the reference exposure conditions.

[0135] Next, in step S3, the matching exposure device 14 performs wafer WF exposure under the set exposure conditions.

[0136] Next, in step S4, the information processing device measures the CD of the entire object pattern within the scanned area obtained by the exposure in step S3. Furthermore, the information processing device measures the CD in multiple scan fields SF as needed and performs averaging. By performing the processing in step S4, the OPE curve of the exposure device 14 to be matched is obtained.

[0137] In step S5, the information processing device determines whether the difference between the OPE curves of the two exposure devices is within an acceptable range. Here, "two exposure devices" refers to the reference exposure device and the exposure device 14 to be matched. That is, the information processing device determines whether the difference between the reference OPE curve obtained in step S1 and the OPE curve obtained in step S4 is within an acceptable range. If the determination result in step S5 is "no," the information processing device proceeds to step S6.

[0138] In step S6, the information processing device determines the exposure conditions that minimize the difference in the OPE curves based on the results of simulation or actual exposure conditions. The "exposure conditions" referred to here include the optical system settings of the exposure device 14, the spectral width of the exposed light, the exposure amount, and the focal point. The optical system settings of the exposure device 14 vary significantly, for example, depending on the shape of the illumination system, such as the NA of the lens in the projection optical system 50, the NA of the lens in the illumination optical system 44, the illumination σ, and the ring band ratio.

[0139] In step S7, the information processing device sets the exposure conditions obtained in step S6 in the exposure device 14 to be matched. After step S7, the process returns to step S3. If the determination result in step S5 is "yes", the information processing device ends. Figure 8 The flowchart.

[0140] In this way, the exposure conditions of the exposure device 14 to be matched are determined so that the difference between the OPE curve of the exposure device 14 to be matched and the reference OPE curve of the reference exposure device converges to an acceptable range. Furthermore, Figure 8 Step S1 can also be implemented by a processor that functions as the exposure control unit of the reference exposure device. Furthermore, Figure 8 Steps S2 to S7 can also be implemented by a processor that functions as the exposure control unit of the exposure device 14 to be matched.

[0141] Figure 9 This is a graph showing an example of a reference OPE curve obtained by measuring the exposure results of a reference exposure device and an OPE curve obtained by measuring the exposure results of an exposure device 14 to be matched. Figure 9 The horizontal axis represents the type of pattern, and the vertical axis represents CD. Figure 9The OPE_ref graph is based on the reference OPE curve of the reference exposure device, and the OPE_mtc graph is based on the OPE curve of the exposure device 14 to be matched.

[0142] 2.6 Topic

[0143] Figure 10 This is a schematic diagram roughly illustrating examples of patterns in the scanning fields (SF) of a wafer (WF). Various patterns are exposed in the scanning fields (SF), which can be subdivided into multiple regions depending on the type of pattern. Figure 10 The image shows an example where three regions (Area 1, Area 2, and Area 3) are set within a scanning field SF. The patterns of each region differ, and the OPE characteristics vary for each region. Furthermore, the number, shape, and arrangement of the regions within the scanning field SF are not limited to... Figure 10 The example shown.

[0144] Figure 11 Examples of OPE curves for Area 1 and Area 2 in scan field SF, scan number #A, are shown. OPE varies depending on the pattern being exposed; therefore, it is preferable to adopt optimal OPE characteristics in each partial area within the scan field SF.

[0145] However, as Figures 7-9 As explained, typical OPE correction adjusts the settings of the illumination optics 44 and projection optics 50 of the exposure apparatus 14. Therefore, it is not possible to adjust the illumination optics 44 and projection optics 50 of the exposure apparatus 14 at high speed within a layer of a certain exposure process. As a result, it is difficult to adjust the OPE characteristics midway through the scanning exposure.

[0146] 3. Implementation Method 1

[0147] 3.1 Overview of the photolithography system

[0148] 3.1.1 Structure

[0149] Figure 12 An example of the structure of the photolithography system 100 of Embodiment 1 is shown. Regarding... Figure 12 The structure shown is for... Figure 2 The differences will be explained. Figure 12 The photolithography system 100 shown is configured to... Figure 2 The structure shown includes an additional photolithography control unit 110, and data transmission and reception lines are added between the photolithography control unit 110 and the exposure control unit 40, and between the photolithography control unit 110 and the laser control unit 20.

[0150] The lithography system 100 includes a laser device 12, an exposure device 14, and a lithography control unit 110. The lithography system 100 is an example of an "exposure system" in this disclosure. In the lithography system 100, a target spectral linewidth Δλt is added as a control parameter for the target laser. Data on the target spectral linewidth Δλt is transmitted from the exposure control unit 40 to the laser control unit 20.

[0151] 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.

[0152] The mask pattern of the mask 46 used in the photolithography system 100, for example, has the same as... Figure 10 The multiple partial regions (Area 1 to 3) described herein correspond to multiple partial regions. For example, a partial region can be divided into continuous strip-shaped regions in a direction orthogonal to the scanning direction. Furthermore, the shape and number of partial regions are not limited to... Figure 10 The example shown.

[0153] A portion of the scan field SF is denoted as "Area(k)". k is the index representing the region number of the portion. When the scan field SF has n portion regions, k can be an integer from 1 to n. There is a one-to-one correspondence between the portion regions in the mask 46 and the portion regions in the scan field SF; therefore, the portion region Area(k) can be understood as a portion region in the mask 46. Multiple patterns are arranged in each portion region Area(k).

[0154] The lithography control unit 110 includes a calculation program for determining the optimal laser control parameters for each area (k). This calculation program includes the following steps: based on pure Fourier imaging optics theory, while changing the settings of the exposure apparatus 14 and the laser control parameters, it calculates the linewidth (OPE) of multiple patterns and uses mathematical methods such as linear or nonlinear optimization to determine the optimal settings of the exposure apparatus 14 and the laser control parameters. Parameters related to the settings of the exposure apparatus 14 include, for example, the NA of the lens in the projection optics system 50, the illumination σ of the illumination optics system 44, and the ring band ratio.

[0155] 3.1.2 Actions

[0156] The lithography control unit 110 calculates the optimal control parameter values ​​for the laser to make the OPE corresponding to each area (K) close to the reference OPE using a calculation program, and saves the calculation results in file A. The laser control parameter values ​​saved in file A include values ​​for the center wavelength, spectral linewidth, and pulse energy. The description "optimal control parameter values" means that the control parameter values ​​of the laser are the OPE curves that converge to the reference OPE curve within an acceptable range for the OPE curve corresponding to the area (K). Sometimes, the OPE curve whose difference from the reference OPE curve converges to an acceptable range is described as the "optimal OPE curve".

[0157] The lithography control unit 110 can also receive and store data related to the laser device 12, including laser control parameters, from the laser control unit 20. For example, the lithography control unit 110 receives and stores data on wavelength λ, spectral linewidth Δλ, and pulse energy E from the laser control unit 20.

[0158] The exposure control unit 40 reads the laser control parameter values ​​corresponding to each area Area(k) of the scanning field SF of the wafer WF from the file A of the photolithography control unit 110.

[0159] The exposure control unit 40 sends the control parameter values ​​of each laser pulse during the exposure of each area(k) to the laser device 12. Subsequent exposure operations can be synchronized with... Figure 2 The exposure system 10 is the same, but further added, for example, by controlling the delay time Δt of the synchronization timing of the oscillator 22 and amplifier 24 of the laser device 12 described later for each pulse, thereby making the spectral linewidth Δλ of each pulse variable.

[0160] 3.2 Examples of Laser Devices

[0161] 3.2.1 Structure

[0162] Figure 13 An example of the structure of the laser device 12 is shown. Figure 13 The laser device 12 shown is a narrowband ArF laser device, including a laser control unit 20, an oscillator 22, an amplifier 24, a monitor module 26, and a gate 28. The oscillator 22 includes a cavity 60, an output coupling mirror 62, a pulse power module (PPM) 64, a charger 66, and a narrowband module (LNM) 68.

[0163] Cavity 60 includes windows 71 and 72, a pair of electrodes 73 and 74, and an electrically insulating component 75. PPM 64 includes a switch 65 and a charging capacitor (not shown), connected to the electrodes 74 via a feed channel of the electrically insulating component 75. Electrode 73 is connected to the grounded cavity 60. Charger 66 charges the charging capacitor of PPM 64 according to instructions from the laser control unit 20.

[0164] The narrowband module 68 and the output coupling mirror 62 constitute an optical resonator. The cavity 60 is configured such that a pair of electrodes 73 and 74 are arranged in the discharge region along the optical path of the resonator. The output coupling mirror 62 is coated with a multilayer film that reflects a portion of the laser generated within the cavity 60 while allowing another portion to pass through.

[0165] The narrowband module 68 includes two prisms 81 and 82, a grating 83, and a rotary stage 84 for rotating the prism 82. The narrowband module 68 uses the rotary stage 84 to rotate the prism 82, thereby changing the incident angle relative to the grating 83 and controlling the oscillation wavelength of the pulsed laser. The rotary stage 84 can also be a rotary stage containing a piezoelectric element capable of high-speed response in a manner that responds to each pulse.

[0166] Amplifier 24 includes an optical resonator 90, cavity 160, PPM 164, and charger 166. The structures of cavity 160, PPM 164, and charger 166 are identical to those of the corresponding elements of oscillator 22. Cavity 160 includes windows 171 and 172, a pair of electrodes 173 and 174, and an electrically insulating component 175. PPM 164 includes a switch 165 and a charging capacitor (not shown).

[0167] The optical resonator 90 is a Fabry-Perot type optical resonator, consisting of a rear mirror 91 and an output coupling mirror 92. The rear mirror 91 partially reflects the laser light and allows the rest to pass through. The output coupling mirror 92 partially reflects the laser light and allows the rest to pass through. The reflectivity of the rear mirror 91 is, for example, 80% to 90%. The reflectivity of the output coupling mirror 92 is, for example, 10% to 30%.

[0168] The monitor module 26 includes beam splitters 181 and 182, a spectrum detector 183, and an optical sensor 184 for detecting the pulse energy of the laser. The spectrum detector 183 may be, for example, an etalon beam splitter. The optical sensor 184 may be, for example, a photodiode.

[0169] 3.2.2 Actions

[0170] After receiving data on the target wavelength λt, spectral linewidth Δλt, and target pulse energy Et from the exposure control unit 40, the laser control unit 20 controls the rotary stage 84 of the LNM68 to make the output wavelength the target wavelength λt, controls it to make the target spectral linewidth Δλt in a manner described later, and controls at least the charger 166 of the amplifier 24 to make the target pulse energy Et.

[0171] After receiving the emission trigger signal Tr from the exposure control unit 40, the laser control unit 20 assigns trigger signals to the switches 165 of PPM164 and 65 of PPM64 respectively, so as to discharge when the pulsed laser output from oscillator 22 is incident on the discharge space of cavity 160 of amplifier 24. As a result, the pulsed laser output from oscillator 22 is amplified and oscillated by amplifier 24. The amplified pulsed laser is sampled by beam splitter 181 of monitor module 26 to measure pulse energy E, wavelength λ, and spectral linewidth Δλ.

[0172] The laser control unit 20 acquires data on pulse energy E, wavelength λ, and spectral linewidth Δλ measured by the monitor module 26, and controls the charging voltage of the charger 166, the oscillation wavelength of the oscillator 22, and the discharge timing of the oscillator 22 and the amplifier 24, so that the difference between pulse energy E and target pulse energy Et, the difference between wavelength λ and target wavelength λt, and the difference between spectral linewidth Δλ and target spectral linewidth Δλt are close to 0.

[0173] The laser control unit 20 can control the pulse energy E, wavelength λ, and spectral linewidth Δλ in pulse units. By controlling the delay time Δt of the discharge timing of cavity 60 of oscillator 22 and cavity 160 of amplifier 24, the spectral linewidth Δλ of the pulsed laser output from laser device 12 can be controlled.

[0174] The pulsed laser beam after passing through the beam splitter 181 of the monitor module 26 is incident on the exposure device 14 through the gate 28.

[0175] 3.2.3 Other

[0176] exist Figure 13 In the example shown, Fabry-Perot resonator 90 is an optical resonator; however, it could also be an amplifier with a ring resonator.

[0177] 3.4 Examples of processing content in the photolithography control unit

[0178] Figure 14 This is a flowchart illustrating an example of the processing performed by the lithography control unit 110 in Embodiment 1. The processor, which functions as the lithography control unit 110, executes the program, thereby achieving... Figure 14 The steps are shown.

[0179] In step S10, the lithography control unit 110 accepts input of data for various parameters, including the parameters of the illumination optical system 44, the parameters of the projection optical system 50, and the parameters of the resist.

[0180] The parameters of the illumination optics system 44 include, for example, the σ value and the illumination shape. The parameters of the projection optics system 50 include, for example, lens data and the lens's NA. The parameters of the resist include, for example, photosensitivity.

[0181] In step S11, the photolithography control unit 110 initializes the index k, which represents the region number of a partial region, to 1. Additionally, in Figure 10 In the example shown, k can take the integer range of 1 to 3.

[0182] In step S12, the photolithography control unit 110 accepts input of pattern information related to the mask pattern of a portion of Area(k).

[0183] In step S13, the photolithography control unit 110 sets the initial values ​​of the laser control parameters. These laser control parameters include, for example, wavelength λ, spectral linewidth Δλ, and exposure dose (dose) D. Alternatively, the exposure dose D may be used instead, or the pulse energy E may be used in addition to it.

[0184] The relationship between the exposure amount D on the wafer surface and the pulse energy E is expressed by the following formula.

[0185] D = T·E·N SL / (Bx·By)

[0186] In the formula, T is the transmittance from the laser device 12 to the wafer WF.

[0187] In step S14, the lithography control unit 110 calculates the OPE curve based on the input data. That is, the lithography control unit 110 calculates the OPE curve of a portion of the region Area(k) according to the given conditions and the calculation program.

[0188] In step S15, the lithography control unit 110 determines whether the absolute value of the difference between the OPE curve calculated in step S14 and the reference OPE curve is within the allowable range. The data of the reference OPE curve is obtained in advance using a reference exposure apparatus and is held in the lithography control unit 110. The index for evaluating the allowable range can be, for example, the sum of the absolute values ​​of the differences between the CD values ​​of each pattern in the OPE curve and the reference OPE curve, and the allowable range can also be a predetermined range.

[0189] If the determination result in step S15 is "No", the lithography control unit 110 proceeds to step S16. In step S16, the lithography control unit 110 sets new laser control parameters and returns to step S14. Steps S14 to S16 are repeated multiple times while changing the values ​​of the laser control parameters until an OPE curve is obtained whose difference from the reference OPE curve is within an acceptable range. The loop of steps S14 to S16 is equivalent to the following process: finding a combination of laser control parameter values ​​that yields the optimal OPE curve close to the reference OPE curve.

[0190] If the determination result in step S15 is "yes", the lithography control unit 110 proceeds to step S17. In step S17, the lithography control unit 110 writes the control parameter data of the laser that yields an OPE curve whose difference from the reference OPE curve is within an acceptable range into file A as OPE(k), representing the OPE characteristics of a partial region Area(k). The control parameter data of the laser written into file A can be, for example, a combination of the values ​​of each parameter, such as wavelength λ(k), spectral linewidth Δλ(k), exposure amount D(k), and pulse energy E(k) (see reference). Figure 15 Wavelength λ(k), spectral linewidth Δλ(k), exposure amount D(k), and pulse energy E(k) are examples of "laser control parameters" in this disclosure. Here, the exposure amount D(k) can be determined based on the pulse energy density on the wafer (not shown) in the exposure apparatus 14 and the number of pulses N. SL The product is used to calculate the result. This data can also be data received by the lithography control unit 110 from the exposure control unit 40.

[0191] In step S18, the lithography control unit 110 determines whether the value of index k is consistent with n. n is the number of regions within the scan field SF, and is the upper limit (maximum value) of the values ​​that index k can take. Figure 10 In the example shown, n = 3.

[0192] If the determination result in step S18 is "no", the lithography control unit 110 increases the value of index k (step S19) and returns to step S12.

[0193] If the determination result in step S18 is "yes", the photolithography control unit 110 ends. Figure 14 The flowchart. According to... Figure 14 The flowchart for calculating laser control parameters is an example of the "Method for Generating Laser Control Parameters" in this disclosure.

[0194] Figure 15 This is a diagram showing an example of data written to file A. For example... Figure 15As shown, in file A, data on the exposure amount D, wavelength λ, spectral linewidth Δλ, and pulse energy E, which exhibit optimal OPE characteristics, are stored for each region, Area(1) to Area(n). Methods for determining the optimal laser control parameters for the OPE(k) of each region, such as those for pure Fourier imaging optics, involve calculating the linewidth (i.e., OPE) related to multiple patterns while changing the settings of the exposure device 14 and / or the laser control parameters, and then using mathematical methods such as linear or nonlinear optimization to determine the optimal settings of the exposure device 14 and the laser control parameters. Examples of the settings for the exposure device 14 include the lens NA, the illumination σ of the illumination optical system 44, and the ring band ratio.

[0195] The mask region corresponding to a partial area (1) is an example of the "first area" in this disclosure, and the mask region corresponding to a partial area (2) is an example of the "second area" in this disclosure. Partial areas (1) and (2) are examples of the "various areas" in this disclosure, respectively. One partial area among multiple partial areas can be equivalent to the "first area" of this disclosure, and another partial area can be equivalent to the "second area" of this disclosure. The OPE curve is an example of the "proximity effect characteristic" in this disclosure, and the baseline OPE curve is an example of the "baseline proximity effect characteristic" in this disclosure. Document A is an example of the "first document" and "document" in this disclosure. The optimal OPE curve obtained for partial area (1) is an example of the "first proximity effect characteristic" in this disclosure. The optimal OPE curve obtained for partial area (2) is an example of the "second proximity effect characteristic" in this disclosure.

[0196] Controlling the laser's control parameters to achieve the optimal OPE curve for each region Area(k) is equivalent to correcting the OPE of a portion of the scanning field SF using the laser's control parameters, and is understood as a form of OPE correction.

[0197] 3.5 Examples of processing content in the exposure control department

[0198] Figure 16 This is a flowchart illustrating an example of the processing performed by the exposure control unit 40 in Embodiment 1. The processor, which functions as the exposure control unit 40, executes the program, thereby achieving... Figure 16 The steps are shown.

[0199] In step S20, the exposure control unit 40 reads the data of file A stored in the lithography control unit 110.

[0200] In step S21, the exposure control unit 40 calculates the laser control parameters based on the information of the mask pattern and the data of document A, so as to perform OPE correction for each region.

[0201] In step S22, the exposure control unit 40 calculates the target values ​​(λt, Δλt, Et) of the control parameters of the laser pulses in each scanning field SF based on the position of each region.

[0202] In step S23, the exposure control unit 40 sends the target values ​​(λt, Δλt, Et) of the control parameters of each pulse of laser and the emission trigger signal Tr to the laser control unit 20, while moving the mask 46 and the wafer WF to expose each scanning field SF.

[0203] In step S24, the exposure control unit 40 determines whether all scan fields SF within the wafer WF have been exposed. If the determination result in step S24 is "No", the exposure control unit 40 returns to step S23. If the determination result in step S24 is "Yes", the exposure control unit 40 ends. Figure 16 The flowchart.

[0204] 3.6 Examples of processing content in the laser control unit

[0205] Figure 17 This is a flowchart illustrating an example of the processing performed by the laser control unit 20 in Embodiment 1. The processor, which functions as the laser control unit 20, executes the program, thereby achieving... Figure 17 The steps are shown.

[0206] In step S31, the laser control unit 20 reads the control parameters (λt, Δλt, Et) of the target laser sent from the exposure control unit 40.

[0207] In step S32, the laser control unit 20 sets the rotary stage 84 of the narrowing module 68 of the oscillator 22 so that the wavelength λ of the pulsed laser output from the laser device 12 is close to the target wavelength λt.

[0208] In step S33, the laser control unit 20 sets the synchronization timing of the oscillator 22 and the amplifier 24 so that the spectral linewidth Δλ of the pulsed laser output from the laser device 12 is close to the target spectral linewidth Δλt.

[0209] In step S34, the laser control unit 20 sets the charging voltage of the amplifier 24 so that the pulse energy E is close to the target pulse energy Et.

[0210] In step S35, the laser control unit 20 waits for the input of the light emission trigger signal Tr and determines whether the light emission trigger signal Tr has been input. If the light emission trigger signal Tr has not been input, the laser control unit 20 repeats step S35. After the light emission trigger signal Tr is input, the laser control unit 20 proceeds to step S36.

[0211] In step S36, the laser control unit 20 uses the monitor module 26 to measure data of the laser control parameters. Through the measurements in step S36, the laser control unit 20 obtains data on wavelength λ, spectral linewidth Δλ, and pulse energy E.

[0212] In step S37, the laser control unit 20 sends the laser control parameter data measured in step S36 to the exposure control unit 40 and the lithography control unit 110.

[0213] In step S38, the laser control unit 20 determines whether to stop laser control. If the determination result in step S38 is "no," the laser control unit 20 returns to step S31. If the determination result in step S38 is "yes," the laser control unit 20 ends. Figure 17 The flowchart.

[0214] The target wavelength λt, target spectral width Δλt, and target pulse energy Et set for a pulsed laser irradiating a portion of Area (1) are examples of "first target wavelength," "first target spectral width," and "first target pulse energy" in this disclosure. Furthermore, the pulsed laser irradiating a portion of Area (1) is an example of "first pulsed laser" in this disclosure. Similarly, the target wavelength λt, target spectral width Δλt, and target pulse energy Et set for a pulsed laser irradiating a portion of Area (2) are examples of "second target wavelength," "second target spectral width," and "second target pulse energy" in this disclosure. Furthermore, the pulsed laser irradiating a portion of Area (2) is an example of "second pulsed laser" in this disclosure. Sending data of target wavelength λt, target spectral width Δλt, and target pulse energy Et from the exposure control unit 40 to the laser control unit 20 is an example of "instructing the laser device on the values ​​of control parameters for the pulsed laser" in this disclosure.

[0215] 3.7 Functions / Effects

[0216] The lithography system 100 of embodiment 1 is implemented Figure 8After performing general OPE correction and adjusting the optical system of the exposure apparatus 14 as described above, the laser control parameters are then adjusted for each position of the area(k) during scanning exposure. According to the lithography system 100 of Embodiment 1, the laser control parameters corresponding to the optimal OPE are determined for the pattern of each area(k) within the scanning field SF, and exposure is performed for each pulse. Therefore, the OPE characteristics dependent on the scanning position can be adjusted at high speed.

[0217] In addition, in Implementation 1, the OPE characteristic was described, but the other proximity effect characteristics are also described in the same way. Furthermore, the same applies to the case where corrections are made to make the combined proximity effect characteristics, which include OPE and other proximity effects, close to the baseline characteristics.

[0218] 3.8 Other

[0219] In Embodiment 1, an example was described in which the functions of the lithography control unit 110 and the exposure control unit 40 are separated. However, it is not limited to this example, and the exposure control unit 40 may also include the functions of the lithography control unit 110.

[0220] also, Figure 14 The calculation process shown can also be pre-calculated using a computer equipped with a calculation program. Figure 15 Such a file A is stored in the storage unit of the lithography control unit 110 or the exposure control unit 40. The lithography control unit 110 may also be a server that manages various parameters used in scanning exposure. The server may also be connected to multiple exposure systems via a network. For example, the server is configured to implement... Figure 14 This calculation process associates the calculated control parameter values ​​with the corresponding area Area(k) and writes them into file A.

[0221] Furthermore, in implementation method 1, in Figure 14 The calculation process shown here ends when the ΔCD value is within the acceptable range. However, it is not limited to this example. Further calculations can be performed to find the control parameters of the laser with the minimum ΔCD value.

[0222] Additionally, in implementation method 1, regarding Figure 14 The ΔCD value shown represents the sum of the absolute values ​​of the differences in CD between the patterns. However, it is not limited to this example; for instance, the ΔCD value can also be a calculated value as shown in the following formula.

[0223] ΔCD=SQRT{(w1·ΔCD1+w2·ΔCD2+…+wnΔCDn) / n}

[0224] wk: Weight of pattern k, ΔCDk: Difference between the CD value of pattern k and the baseline value, n: Number of patterns

[0225] 4. Implementation Method 2

[0226] 4.1 Structure

[0227] Figure 18 An example of the structure of the photolithography system 102 of Embodiment 2 is shown. The photolithography system 102 of Embodiment 2 is configured to... Figure 12 A wafer inspection apparatus 310 is added to the structure. Other structures can be the same as in Embodiment 1. The wafer inspection apparatus 310 irradiates the wafer WF with a laser and measures its reflected or diffracted light, thereby enabling the determination of CD, the height of the wafer WF, and the superposition. Alternatively, the wafer inspection apparatus 310 can also 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.

[0228] The lithography control unit 110 is connected to a line for transmitting and receiving data between itself and the wafer inspection control unit 320.

[0229] 4.2 Actions

[0230] The exposed wafer WF, which has been exposed using the exposure apparatus 14, is held in the wafer holder 352 of the wafer inspection apparatus 310, and various measurements are performed by the wafer inspection apparatus 310. The lithography control unit 110 correlates the pattern and CD value at each position on the wafer WF measured by the wafer inspection apparatus 310 with the control parameters of the laser that was exposed at each position.

[0231] The lithography control unit 110 calculates the optimal control parameters for the laser used for OPE correction in each region based on the actual exposure results (pattern and CD) of the wafer WF, and saves this data as file A. Other operations are the same as in Embodiment 1. The exposed wafer WF that becomes the object of inspection by the wafer inspection apparatus 310 is an example of the "exposed semiconductor substrate" in this disclosure.

[0232] Figure 19 This is a flowchart illustrating an example of the processing in the lithography control unit 110 of Embodiment 2.

[0233] In step S40, the lithography control unit 110 sends a measurement signal of the wafer WF to the wafer inspection apparatus 310. The wafer inspection apparatus 310 performs measurements based on the measurement signal from the lithography control unit 110.

[0234] In step S41, the lithography control unit 110 determines whether the wafer wafer fabrication (WF) inspection has been completed. For example, after completing the wafer WF inspection, the wafer inspection apparatus 310 sends an inspection completion signal indicating that the inspection is complete to the lithography control unit 110. The lithography control unit 110 determines whether the inspection is complete based on whether the inspection completion signal is received.

[0235] If the determination result in step S41 is "no", the system remains in standby mode during this step. If the determination result in step S41 is "yes", the lithography control unit 110 proceeds to step S42.

[0236] In step S42, the photolithography control unit 110 receives the pattern and CD values ​​at various locations of the exposed wafer WF from the wafer inspection apparatus 310. Information about the pattern can be pre-stored in cases where it is difficult to obtain from the measurement results of the wafer inspection apparatus 310.

[0237] In step S43, the photolithography control unit 110 sets the value of index k to k = 1.

[0238] Next, in step S44, the lithography control unit 110 sets the value of ΔCDmax as the initial value of ΔCDmin. ΔCDmin is the minimum difference between the CD curve and the target CD curve. ΔCDmax is the maximum difference between the CD curve and the target CD curve.

[0239] Next, in step S45, the lithography control unit 110 sets the value of index i to i = 1. Index i is a set number used to identify the control parameter set of the laser. The value of index i represents a set of data (combination of data) of laser control parameters.

[0240] In step S46, the lithography control unit 110 calculates the control parameter set (i) for the laser in a partial area (K). Based on the exposure apparatus 14 and the laser apparatus 12, and according to the wafer WF number and its scan number, the lithography control unit 110 generates control parameter data for each pulse of the laser in each scan and stores it in file A. The control parameter set (i) for the laser in the partial area (K) can be calculated based on this stored data.

[0241] In step S47, the lithography control unit 110 calculates the OPE curve (k,i) related to each area Area (k,i) under the exposure conditions of the laser control parameter set (i).

[0242] In step S48, the lithography control unit 110 calculates the difference ΔCD between the reference OPE curve (k) and the measured OPE curve (k,i) of the area (k). ΔCD can be, for example, the sum of the absolute values ​​of the differences in CD values ​​of each pattern.

[0243] In step S49, the lithography control unit 110 determines whether ΔCDmin > ΔCD. If the determination result in step S49 is "yes", the lithography control unit 110 proceeds to step S50 to perform the process of replacing the value of ΔCDmin with ΔCD.

[0244] Then, in step S51, the lithography control unit 110 saves the dataset of a portion of the area(k) and the set of control parameters (i) of the laser as the correction data of OPE(k) in file A.

[0245] After step S51, the lithography control unit 110 proceeds to step S52. Furthermore, if the determination result in step S49 is "no", the lithography control unit 110 skips steps S50 to S51 and proceeds to step S52.

[0246] In step S52, the lithography control unit 110 determines whether the value of index i is consistent with the predetermined upper limit value imax. If the determination result in step S52 is "no", the lithography control unit 110 increases the value of index i (step S53) and returns to step S46. If the determination result in step S52 is "yes", the lithography control unit 110 proceeds to step S54.

[0247] In step S54, the lithography control unit 110 determines whether the value of index k is consistent with a predetermined value n. If the determination result in step S54 is "no", the lithography control unit 110 increments the value of index k (step S55) and returns to step S44. If the determination result in step S54 is "yes", the lithography control unit 110 ends. Figure 19 The flowchart.

[0248] Figure 20 Examples of OPE curves for each set (i) of control parameters for the laser in a partial region Area(k) are shown. Figure 20 In this context, Area(k) represents the baseline OPE curve, and Area(k,i) represents the OPE curve where ΔCD becomes the minimum value.

[0249] 4.3 Functions / Effects

[0250] According to the lithography system 102 of embodiment 2, the laser control parameters corresponding to the optimal OPE can be determined for the pattern of each part of the wafer WF in the scanning field SF based on the actual exposure results, and exposure is performed according to each pulse.

[0251] As a result, the CD error caused by individual differences (machine variability) of the exposure device 14 can be corrected to the optimal OPE by adjusting the laser control parameters. That is, even with individual differences in the exposure device 14, the desired resist pattern can be formed in the same mask pattern.

[0252] According to Embodiment 2, the data in file A can be continuously updated based on the actual exposure results. Therefore, exposure can be performed with the optimal laser control parameters for each partial area, which are most suitable for the exposure process at that point in time. As a result, the stability of the CD value of the resist pattern is improved.

[0253] 4.4 Other

[0254] In implementation method 2, a test exposure may also be performed initially, thereby generating data for file A. The order in which the data for file A is generated by performing the test exposure is as follows, for example.

[0255] [Sequence a] For each scan of the wafer's WF, the control parameter set (λt, Δλt, Et) of the target laser is set to a certain target value, and a scan exposure is performed. Then, the values ​​of the control parameter set (λt, Δλt, Et) of the target laser are changed for the next scan exposure, and a scan exposure is performed again with a certain target value. This process is repeated to perform the scan exposure.

[0256] [Sequence b] can also generate the initial file A based on the inspection results of the wafer WF after exposure in sequence a and the control parameter set (i) of the laser at this time.

[0257] 5. Implementation Method 3

[0258] 5.1 Structure

[0259] Figure 21 An example of the structure of the photolithography system 103 in Embodiment 3 is shown. Regarding... Figure 21 The structure shown is for... Figure 18 The differences will be explained. Figure 21 In the lithography system 103 shown, the control parameters of the target laser are changed to cumulative shift values. That is, instead of the target wavelength λt, target linewidth Δλt, and target pulse energy Et sent from the exposure control unit 40 to the laser control unit 20 as control parameters of the target laser, the cumulative shift values ​​λmvt of the target wavelength, Δλmvt of the target linewidth, and Dmvt of the target pulse energy are used. Furthermore, based on these cumulative shift values ​​of the target laser control parameters, the exposure control unit 40 applies a pulse number N equivalent to the number of samples accumulated during shift accumulation. SL The information is sent to the laser control unit 20. Other structures and... Figure 18 same.

[0260] Here, in this specification, the cumulative value of the movement of the laser control parameters is defined as follows.

[0261] The parameters for spectral correlation, as described later, will be based on the number of samples N. SL The wavelength for calculating the spectral waveform after moving accumulation is set as λmv, and the spectral linewidth is set as Δλmv.

[0262] Regarding the pulse energy correlation parameters, the number of samples N will be used as a reference. SL The cumulative value of the pulse energy after the moving accumulation is set as Dmv.

[0263] Furthermore, the target values ​​for these parameters are expressed as λmvt, Δλmvt, and Dmvt.

[0264] 5.2 Actions

[0265] Figure 21 The photolithography control unit 110 aligns the pattern and CD value at each position on the wafer WF measured by the wafer inspection device 310 with the control parameters (movement accumulation value) of the laser exposed at each position.

[0266] The lithography control unit 110 calculates the optimal control parameters (movement accumulation value) for the laser used for OPE correction in each region based on the actual exposure results (pattern and CD) of the wafer WF, and saves the calculated data as file A2. The laser control parameters saved in file A2 are the movement accumulation values.

[0267] The laser control unit 20 receives the control parameters (movement cumulative value) of the laser of the target, calculates the target spectrum waveform F(λ)t and the target pulse energy Et of the next pulse, and controls the laser device 12 to achieve these target values.

[0268] 5.3 Examples of processing content in the laser control unit

[0269] Figure 22 This is a flowchart illustrating an example of the processing performed by the laser control unit 20 in Embodiment 3. Regarding... Figure 22 The flowchart shown is for... Figure 17 The differences will be explained. Figure 22 The flowchart shown replaces Figure 17 Step S31 includes steps S30 and S31a. Furthermore, Figure 22 The flowchart shown replaces Figure 17 Step S37 includes steps S37a and S37b.

[0270] In step S30, the laser control unit 20 reads the accumulated movement values ​​of the control parameters for the target laser sent from the exposure control unit 40. The data acquired by the laser control unit 20 includes λmvt, Δλmvt, Dmvt, and N. SL The data.

[0271] In step S31a, the laser control unit 20 calculates the parameter values ​​(λt, Δλt, Et) of the target laser for the next pulse. An example of the processing applied in step S31a is provided below. Figure 23 and Figure 24 The following will describe steps S32 through S36, which follow step S31a. Figure 17 same.

[0272] Following step S36, in step S37a, the laser control unit 20 writes the cumulative shift values ​​(λmv, Δλmv, Dmv) of the laser control parameters and the spectral waveform data into file B. An example of the data stored in file B is provided below. Figure 25 To be described later.

[0273] Next, in step S37b, the laser control unit 20 sends the measured cumulative value of the laser control parameters to the exposure control unit 40 and the lithography control unit 110. After step S37b, the process proceeds to step S38. Subsequent steps are the same as... Figure 17 same.

[0274] Figure 23 It shows that it is applied to Figure 22 The flowchart shows an example of the processing content of step S31a. Figure 24 Showing through Figure 23 The calculation steps shown are examples of the spectral waveforms obtained.

[0275] exist Figure 23 In step S61, the laser control unit 20 converts the target values ​​λmvt and Δλmvt into the normalized spectral waveform Iaumv(λ)t of the target. Based on the cumulative shift value λmvt of the target wavelength and the cumulative shift value λmvt of the target spectral linewidth, an approximate normalized spectral waveform Iaumv(λ)t of the target is obtained. Alternatively, the spectral linewidth can be a spectral width containing 95% of the energy.

[0276] Figure 24 The waveform shown at the top of the diagram illustrates the normalized spectral waveform Iaumv(λ)t of the target calculated in step S61. The spectral waveform of a typical excimer laser can be approximated by a Lorentz distribution, a Gaussian distribution, or a spectrum in between.

[0277] Then, the laser control unit 20 calculates the target's moving cumulative spectrum waveform Smv(λ)t. The target's moving cumulative spectrum waveform Smv(λ)t is expressed using the following formula.

[0278] Smv(λ)t=Iaumv(λ)t·N SL

[0279] from Figure 24 The waveform diagram shown in the second segment above illustrates an example of the target's moving cumulative spectrum waveform Smv(λ)t calculated in step S61.

[0280] In step S63, the laser control unit 20 accumulates data from the past N based on the data in document B. SL From the spectral waveform data of the pulse from -1 to the immediately preceding pulse, calculate the spectral waveform Spp(λ). Figure 24 The waveform shown in the third segment above the top illustrates an example of the spectral waveform Spp(λ) calculated in step S63. Figure 24 The waveform shown by the dashed line in the curve of the spectral waveform Spp(λ) represents the spectral waveform of the previous pulse measured by the instrument.

[0281] Next, in step S64, the target spectrum waveform F(λ)t for the next pulse is calculated based on the difference between the target's cumulative motion spectrum waveform Smv(λ)t and Spp(λ). The target spectrum waveform F(λ)t is expressed by the following formula.

[0282] F(λ)t=Smv(λ)t-Spp(λ)

[0283] Figure 24 The waveform diagram shown at the bottom of the diagram illustrates an example of the target spectrum waveform F(λ)t of the next pulse calculated in step S64.

[0284] Then, in step S66, the laser control unit 20 calculates the target wavelength λt and the target spectral linewidth Δλt based on the target spectral waveform F(λ)t of the next pulse.

[0285] The laser control unit 20 performs the processes of steps S72 to S73 in parallel or concurrently with the processes of steps S61 to S66.

[0286] In step S72, the laser control unit 20 accumulates data from the past N based on the data in document B. SL Calculate Esump using the energy from the -1 pulse to the immediately preceding pulse.

[0287] In step S73, the laser control unit 20 calculates the target pulse energy Et based on the difference between Dmvt and Esump.

[0288] Et = Dmvt - Esump

[0289] After steps S66 and S73, the laser control unit 20 ends. Figure 23 The flowchart, return Figure 22 The main process.

[0290] 5.4 Data Example for File B

[0291] Figure 25 This is a diagram showing an example of data written to file B. For example... Figure 25 As shown, in file B, associated with the time data TIME of each pulse, there are records containing data including pulse energy E, cumulative value of moving cumulative pulse energy Dmv, wavelength λ, wavelength λmv of moving cumulative spectrum waveform, spectral linewidth Δλ, spectral linewidth Δλmv of moving cumulative spectrum waveform, and spectrum waveform F(λ).

[0292] Here, the wavelength λmv(zN) of the moving cumulative spectrum waveform SL +1) and the spectral linewidth Δλmv(zN) of the moving cumulative spectrum waveform. SL +1) is calculated from the spectral waveform Smv(λ) after accumulating the light intensity at each wavelength, from the pulse (zN) SL +1) is the value obtained from the data of the spectral waveform F(λ) of the pulse z. Document B is an example of "Document 2" in this disclosure. Figure 25 The values ​​of pulse energy E, wavelength λ, and spectral linewidth Δλ shown are examples of the "measured values ​​of control parameters for pulsed lasers" in this disclosure.

[0293] 5.5 Functions / Effects

[0294] According to the lithography system 103 of embodiment 3, the control parameter value of the laser exposed in the scanning field SF is strictly defined as the moving cumulative value.

[0295] Regarding the laser output from the laser device, calculate the target value of the control parameters for the next laser pulse and control it so that the control parameters of the laser become the cumulative value of the target's movement.

[0296] As a result, exposure can be performed with the optimal control parameters (movement cumulative value) of the laser for OPE correction in each region.

[0297] 5.6 Other

[0298] In implementation method 3, regarding the wavelength λmv(zN) of the moving cumulative spectrum waveform... SL +1) and the spectral linewidth Δλmv(zN) of the moving cumulative spectrum waveform. SLThe calculation of +1) is based on the actual measured spectral waveform, but it is not limited to this example. For instance, an approximate formula can also be derived based on the measured wavelength λ and spectral linewidth Δλ, and this approximate formula can be saved as data in file A.

[0299] In embodiment 3, the laser device 12 receives each motion accumulation value (λmvt, Δλmvt, Dmvt) and the number of pulses N for motion accumulation. SL As control parameters for the laser, the laser control unit 20 calculates the control parameters (λt, Δλt, Et) of the target laser for the next pulse to control the laser device 12; however, this is not limited to this example. For instance, this calculation can also be performed using the lithography control unit 110, which directly sends the control parameters (λt, Δλt, Et) of the target laser for each pulse to the laser control unit 20, or it can be sent to the laser control unit 20 via the exposure control unit 40. Similarly, this calculation can also be performed using the exposure control unit 40, which directly sends the control parameters (λt, Δλt, Et) of the target laser for each pulse to the laser control unit 20.

[0300] In implementation method 3, based on the number of samples N SL The moving cumulative wavelength λmv and the moving cumulative spectral linewidth Δλmv are obtained from the moving cumulative spectral waveform Smv(λ). However, this is not limited to this example; even according to the moving average spectrum Fmv(λ)=Smv(λ) / N SL The wavelength and spectral linewidth are calculated and become exactly the same λmv and Δλmv.

[0301] In addition, the number of samples N is calculated. SL The cumulative value of the moving average pulse energy is Dmv. However, not limited to this example, the moving average pulse energy Emv = Dmv / N can also be calculated from Dmv. SL It is used as a control parameter for pulsed lasers.

[0302] Therefore, in this specification, the moving cumulative value and moving average value of the control parameters for pulsed lasers are synonymous. Specifically, the moving average value, as the control parameters for pulsed lasers, can also be the wavelength λmv, spectral linewidth Δλmv, and moving average pulse energy Emv, which are obtained from the moving average spectral waveform.

[0303] 6. Examples of excimer laser devices using solid-state laser devices as oscillators

[0304] 6.1 Structure

[0305] Figure 13 The laser device 12 described herein illustrates a structure using a narrowband gas laser device as the oscillator 22; however, the structure of the laser device is not limited to this. Figure 13Examples.

[0306] Figure 26 Another structural example of a laser device is shown. It can also be replaced with... Figure 13 The laser device 12 shown is used Figure 26 The laser device 212 shown. Regarding... Figure 26 The structure shown is for... Figure 13 Identical or similar elements are labeled with the same number and their descriptions are omitted.

[0307] Figure 26 The laser device 212 shown is an excimer laser device that uses 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.

[0308] The solid-state laser system 222 includes a semiconductor laser system 230, a titanium-doped sapphire amplifier 232, a pumped pulsed laser 234, a wavelength conversion system 236, and a solid-state laser control unit 238.

[0309] The semiconductor laser system 230 includes a distributed feedback (DFB) semiconductor laser that outputs a CW laser with a wavelength of approximately 773.6 nm, and a semiconductor optical amplifier (SOA) that pulses the CW laser. An example of the structure of the semiconductor laser system 230 is shown below. Figure 27 To be described later.

[0310] The titanyl sapphire amplifier 232 includes a titanyl sapphire crystal. The titanyl sapphire crystal is positioned in the optical path of the pulsed laser after pulse amplification by the SOA of the semiconductor laser system 230. The pulsed 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.

[0311] The wavelength conversion system 236 includes multiple nonlinear optical crystals that convert the wavelength of the incident pulsed laser to output a fourth-harmonic pulsed laser. The 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 KBa2BO3F2. Each crystal is positioned on a rotating stage (not shown) and configured to allow for variation of the incident angle relative to the crystal.

[0312] The solid-state laser control unit 238 controls the semiconductor laser system 230, the pumped pulsed laser 234, and the wavelength conversion system 236 according to the instructions from the laser control unit 220.

[0313] The excimer amplifier 224 includes a cavity 160, a PPM 164, a charger 166, a convex mirror 241, and a concave mirror 242. The cavity 160 includes windows 171 and 172, a pair of electrodes 173 and 174, and an electrically insulating component 175. ArF laser gas is introduced into the cavity 160. The PPM 164 includes a switch 165 and a charging capacitor.

[0314] The excimer amplifier 224 is structured such that a seed light with a wavelength of 193.4 nm passes through the discharge space between a pair of electrodes 173 and 174 three times and is amplified. Here, the seed light with a wavelength of 193.4 nm is a pulsed laser output from the solid-state laser system 222.

[0315] The convex mirror 241 and the concave mirror 242 are configured such that the pulsed laser output from the solid-state laser system 222 outside the cavity 160 is beam-amplified in a 3-pass manner.

[0316] Seed light with a wavelength of approximately 193.4 nm incident on excimer amplifier 224 is reflected by convex mirror 241 and concave mirror 242, thereby passing through the discharge space between a pair of discharge electrodes 412 and 413 three times. As a result, the beam of seed light is expanded and amplified.

[0317] 6.2 Actions

[0318] After receiving the target wavelength λt, target spectral width Δλt, and target pulse energy Et from the exposure control unit 40, the laser control unit 220 calculates the target wavelength λ1ct and target spectral width Δλ1cht of the pulsed laser from the semiconductor laser system 230, which are these target values, for example, based on table data or approximation formulas.

[0319] The laser control unit 220 sends the target wavelength λ1ct and the target spectral linewidth Δλ1cht to the solid-state laser control unit 238 and sets the charging voltage for the charger 166 so that the pulsed laser output from the excimer amplifier 224 becomes the target pulse energy Et.

[0320] The solid-state laser control unit 238 controls the semiconductor laser system 230 to bring the emitted pulsed laser light from the semiconductor laser system 230 close to the target wavelength λ1ct and the target spectral linewidth Δλ1cht. The control method implemented by the solid-state laser control unit 238 uses... Figures 27-30 To be described later.

[0321] In addition, the solid-state laser control unit 238 controls two rotating stages (not shown) to achieve the incident angle that maximizes the wavelength conversion efficiency of the LBO crystal and KBBF crystal in the wavelength conversion system 236.

[0322] After the exposure control unit 40 sends a light emission trigger signal Tr to the laser control unit 220, a trigger signal is synchronously input to the switch 165 of the PPM164 of the semiconductor laser system 230, the pump pulsed laser 234, and the excimer amplifier 224. As a result, a pulsed current is input to the SOA of the semiconductor laser system 230, and amplified pulsed laser light is output from the SOA.

[0323] A pulsed laser is output from the semiconductor laser system 230 and further amplified in a titanate-sapphire amplifier 232. This pulsed laser is then incident on a wavelength conversion system 236. As a result, a pulsed laser with a target wavelength λt is output from the wavelength conversion system 236.

[0324] After receiving the emission trigger signal Tr from the exposure control unit 40, the laser control unit 220 sends trigger signals to the switch 165 of the SOA 260 and PPM 164 of the semiconductor laser system 230 (described later) and the pump pulse laser 234, respectively, so as to discharge when the pulse laser output from the solid-state laser system 222 is incident on the discharge space of the cavity 160 of the excimer amplifier 224.

[0325] As a result, the pulsed laser output from the solid-state laser system 222 is amplified in a 3-pass manner in the excimer amplifier 224. The pulsed laser amplified by the excimer amplifier 224 is sampled by the beam splitter 181 of the monitor module 26, the pulse energy E is measured using the optical sensor 184, and the wavelength λ and spectral linewidth Δλ are measured using the spectral detector 183.

[0326] The laser control unit 220 can also perform correction control on the charging voltage of the charger 166, the wavelength λ, and the spectral linewidth Δλ of the pulsed laser output from the semiconductor laser system 230 based on the pulse energy E, wavelength λ, and spectral linewidth 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 linewidth Δλ and the target spectral linewidth Δλt are close to 0.

[0327] 6.3 Description of Semiconductor Laser Systems

[0328] 6.3.1 Structure

[0329] Figure 27An example of the structure of a semiconductor laser system 230 is shown. The semiconductor laser system 230 includes a single-longitudinal-mode distributed feedback semiconductor laser 250, a semiconductor optical amplifier (SOA) 260, a function generator (FG) 261, a beam splitter 264, a spectrum monitor 266, and a semiconductor laser control unit 268. The distributed feedback semiconductor laser is referred to as a "DFB laser".

[0330] The DFB laser 250 outputs CW (Continuous Wave) laser light with a wavelength of approximately 773.6 nm. The oscillation wavelength of the DFB laser 250 can be changed through current control and / or temperature control.

[0331] 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, with a grating 274 at the boundary between the active layer 272 and the second cladding layer 273.

[0332] 6.3.2 Actions

[0333] The oscillation center wavelength of the DFB laser 250 can be changed by varying the set temperature T and / or current value A of the semiconductor laser element 251.

[0334] When the spectral linewidth is controlled by rapidly chirping the oscillation wavelength of the DFB laser 250, the spectral linewidth can be controlled by rapidly changing the current value A of the current flowing through the semiconductor laser element 251.

[0335] That is, the semiconductor laser control unit 268 sends the DC component value A1dc, the AC component variation amplitude A1ac, and the AC component period A1 to the function generator 257. T The values ​​of each parameter are used as current control parameters, thereby enabling high-speed control of the center wavelength λ1chc and spectral linewidth Δλ1ch of the pulsed laser output from the semiconductor laser system 230.

[0336] The spectrum monitor 266 can, for example, use a spectrometer or a heterodyne interferometer to measure wavelengths.

[0337] The function generator 257 outputs an electrical signal with a waveform corresponding to the current control parameters specified from the semiconductor laser control unit 268 to the current control unit 256. The current control unit 256 performs current control to cause the current corresponding to the electrical signal from the function generator 257 to flow through the semiconductor laser element 251. Alternatively, the function generator 257 may be disposed outside the DFB laser 250. For example, the function generator 257 may also be included in the semiconductor laser control unit 268.

[0338] Figure 28 This is a conceptual diagram of spectral linewidth achieved through chirping. The spectral linewidth Δλ1ch is measured as the difference between the maximum and minimum wavelengths generated by chirping.

[0339] Figure 29 This is a schematic diagram illustrating the relationship between the current flowing through a semiconductor laser, the chirp-based wavelength variation, the spectral waveform, and the light intensity. Figure 29 The graph GA shown in the lower left section is a graph showing the change in the current value A of the current flowing through the semiconductor laser element 251. Figure 29 The graph GB shown in the lower central section is a graph showing the chirp generated by the current passing through graph GA. Figure 29 The curve GC shown in the upper section is a schematic diagram of the spectral waveform obtained by the chirping of the curve GB. Figure 29 The graph GD shown on the lower right is a graph showing the change in the light intensity of the laser output from the semiconductor laser system 230 as a result of the current passing through graph GA.

[0340] The current control parameters of the semiconductor laser system 230, as shown in graph GA, include the following values.

[0341] A1dc: The DC component of the current flowing through the semiconductor laser element.

[0342] A1ac: The variation in the AC component of the current flowing through a semiconductor laser element (the difference between the maximum and minimum values ​​of the current).

[0343] A1 T The period of the AC component of the current flowing through a semiconductor laser element.

[0344] exist Figure 29 In the examples shown, the AC component, which is a current control parameter, is an example of a triangular wave, illustrating how variations in the current through the triangular wave result in minimal changes in the intensity of the CW laser output from the DFB laser 250.

[0345] Here, the preferred amplification pulse duration D of SOA260 is... TW Period A1 of AC componentT The relationship satisfies the following equation (1).

[0346] D TW =n·A1 T (1)

[0347] n is an integer greater than or equal to 1.

[0348] By satisfying the relationship in equation (1), the SOA260 can suppress changes in the spectral waveform of the amplified pulsed laser even when pulse amplification is performed at any time.

[0349] Furthermore, even if equation (1) is not satisfied, the pulse width range in SOA260 is, for example, 10 ns to 50 ns. The period A1 of the AC component of the current flowing in the semiconductor laser element 251 is... T It is much shorter than the pulse width of SOA260 (the time width D of the amplified pulse). TW The period of ). For example, the preferred period is A1. T The pulse width in the semiconductor optical amplifier 260 is greater than or equal to 1 / 1000 and less than or equal to 1 / 10. More preferably, it is greater than or equal to 1 / 100 and less than or equal to 1 / 100.

[0350] Furthermore, the rise time of SOA260 is preferably 2ns or less, and more preferably 1ns or less. Figure 30 As shown, the rise time referred to here is the time Rt required for the amplitude of the pulse current waveform to increase from 10% of the maximum amplitude to 90%.

[0351] 6.3.3 Other

[0352] exist Figure 29 The example shown illustrates a triangular wave as an example of the AC component of the current; however, it is not limited to this example, and any waveform that changes with a certain period can be used. Other examples besides triangular waves include sine waves, square waves, etc. By controlling the waveform of this AC component, various target spectral waveforms can be generated.

[0353] 6.4 Functions / Effects

[0354] The laser device 212, which uses a solid-state laser system 222 as an oscillator, has the following advantages compared to the case where an excimer laser is used as an oscillator.

[0355] [1] The solid-state laser system 222 can control the wavelength λ and spectral linewidth Δλ at high speed and with high precision by controlling the current value A of the DFB laser 250. That is, if the laser device 212 receives data of the target wavelength λt and the target spectral linewidth Δλt, it can immediately control the current value A of the DFB laser 250, thereby controlling the oscillation wavelength and spectral linewidth Δλ at high speed. Therefore, it can change and control the wavelength λ and spectral linewidth Δλ of the pulsed laser output from the laser device 212 at high speed and with high precision according to each pulse.

[0356] [2] Furthermore, by controlling the current value A of the DFB laser 250 to make it chirp, it is possible to generate spectral waveforms of various functions that are different from the usual spectral waveforms.

[0357] [3] Therefore, when controlling the wavelength λmv or linewidth Δλmv of the moving cumulative spectrum, it is preferable to have a laser device with an oscillator and an excimer amplifier, the moving cumulative spectrum being obtained from the spectral waveform of the moving cumulative value of the spectral waveform as a laser control parameter, and the oscillator using a solid-state laser system including a DFB laser.

[0358] 6.5 Other

[0359] As an implementation of a solid-state laser device, it is not limited to Figures 26-30 The example shown could be a solid-state laser system comprising a DFB laser with a wavelength of approximately 1547.2 nm and an SOA, with the wavelength conversion system outputting 193.4 nm light at its 8th harmonic. Alternatively, a system could be provided as another solid-state laser device, comprising a CW-oscillating DFB laser and an SOA, where the current flowing through the DFB laser is controlled, and a pulsed current flows through the SOA, thereby pulse amplifying the wavelength.

[0360] exist Figure 26 In the example, a multi-pass amplifier is shown as an excimer amplifier, but it is not limited to this embodiment. For example, it could also be an amplifier with an optical resonator such as a Fabry-Perot resonator or a ring resonator.

[0361] 7. Hardware structure of various control units

[0362] 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 through a combination of hardware and software from one or more computers. Software is synonymous with program. A programmable logic controller (PLC) is included in the concept of a computer. A computer can be configured to include a CPU (Central Processing Unit) and memory. The CPU in a computer is an example of a processor.

[0363] In addition, some or all of the processing functions of the control device can also be implemented using integrated circuits such as FPGA (Field Programmable Gate Array) and ASIC (Application Specific Integrated Circuit).

[0364] Furthermore, a single control device can perform the functions of multiple control devices. Moreover, in this disclosure, the control devices can also be interconnected via communication networks such as local area networks (LANs) or the Internet. In a distributed computing environment, program units can also be stored in both local and remote memory storage devices.

[0365] 8. Manufacturing methods for electronic devices

[0366] Figure 31 An example of the structure of the exposure apparatus 14 is schematically shown. The exposure apparatus 14 includes an illumination optics system 44 and a projection optics system 50. The illumination optics system 44 illuminates the mask pattern of a mask 46 disposed on a mask stage 48 (not shown) using a laser incident from the laser device 12. The projection optics system 50 reduces and projects the laser light after it has passed through the mask 46, so that it images onto a workpiece (not shown) disposed on a workpiece stage WT. The workpiece may be a photosensitive substrate such as a semiconductor wafer coated with resist. The workpiece stage WT may be a wafer stage 54.

[0367] Exposure apparatus 14 moves the mask stage 48 and the workpiece stage WT synchronously and parallelly, thereby exposing the workpiece to laser light reflecting the mask pattern. After transferring the mask pattern onto a semiconductor wafer through this exposure process, a semiconductor device can be manufactured through multiple processes. The semiconductor device is an example of the "electronic device" in this disclosure.

[0368] Figure 31 The laser device 12 in the middle may include Figure 26 The laser device 212, etc., of the solid-state laser system 222 described herein.

[0369] 9. Other

[0370] The foregoing description is not a limitation but a simple illustration. Therefore, those skilled in the art will understand that modifications can be made to embodiments of this disclosure without departing from the claims. Furthermore, those skilled in the art will understand the use of embodiments of this disclosure in combination.

[0371] Unless explicitly stated otherwise, all terms used in this specification and claims should be interpreted as "non-limiting." For example, terms such as "comprising," "all," "having," and "possessing" should be interpreted as "excluding the presence of structural elements other than those described." Furthermore, the modifier "a" should be interpreted as meaning "at least one" or "one or more." Additionally, 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." Moreover, it should be interpreted as also including combinations of these elements with portions other than "A," "B," and "C."

Claims

1. An exposure system which irradiates a reticle with a pulsed laser to perform a scanning exposure on a semiconductor substrate, wherein, The exposure system has: a laser device that outputs the pulsed laser light; an illumination optical system that guides the pulsed laser light to the reticle; a reticle stage that moves the reticle; and a processor that controls the output of the pulsed laser light from the laser device and the movement of the reticle based on the reticle stage, the reticle has a first region and a second region that are scan regions within a scan field, the first region and the second region differ in pattern form, the processor instructs the laser device of a target value of a control parameter of the pulsed laser light corresponding to each of the first region and the second region, based on a proximity effect characteristic corresponding to each of the regions, to output the pulsed laser light in which a difference from a reference proximity effect characteristic in each of the regions converges to a proximity effect characteristic within an allowable range, the control parameter including at least one of wavelength, spectral line width, each of the target values being different.

2. The exposure system according to claim 1, wherein the processor calculates a proximity effect characteristic corresponding to each of the first region and the second region, the processor determines a value of the control parameter of the pulsed laser light appropriate for each of the regions so that a proximity effect characteristic calculated by the calculation converges to a proximity effect characteristic within the allowable range from the reference proximity effect characteristic.

3. The exposure system according to claim 1, wherein the exposure system further has a projection optical system that projects an image of the reticle to the semiconductor substrate, the processor calculates a proximity effect characteristic corresponding to each of the first region and the second region using a plurality of data including a parameter of the illumination optical system, a parameter of the projection optical system, a parameter of a resist coated on the semiconductor substrate, a reticle pattern of the reticle, and the control parameter of the pulsed laser light, the processor determines each of the target values of the control parameter of the pulsed laser light in which a difference from the reference proximity effect characteristic in each of the regions converges to a proximity effect characteristic within the allowable range, based on a result of the calculation, the processor saves each of the target values of the determined control parameter in association with the corresponding each of the regions in a first file.

4. The exposure system according to claim 1, wherein the exposure system further has a server that manages a parameter used in the scan exposure, the server calculates a proximity effect characteristic corresponding to each of the first region and the second region, determines each of the target values of the control parameter of the pulsed laser light in which a difference from the reference proximity effect characteristic in each of the regions converges to a proximity effect characteristic within the allowable range, based on a result of the calculation, saves each of the target values of the determined control parameter in association with the corresponding each of the regions in a first file.

5. The exposure system according to claim 1, wherein The processor uses a first file including data that determines each of the target values of the control parameters of the pulsed laser that converges the proximity effect characteristics to the proximity effect characteristics that differ from the reference within the allowable range, for each of the first region and the second region, to determine the target values of the control parameters of the pulsed laser for each pulse of the each region.

6. The exposure system according to claim 1, wherein The control parameters further include a pulse energy.

7. The exposure system according to claim 6, wherein The processor sets a first target wavelength, a first target spectral linewidth, and a first target pulse energy of the pulsed laser in accordance with a first proximity effect characteristic corresponding to the first region, and controls the laser device to irradiate a first pulsed laser to the first region, The processor sets a second target wavelength, a second target spectral linewidth, and a second target pulse energy of the pulsed laser in accordance with a second proximity effect characteristic corresponding to the second region, and controls the laser device to irradiate a second pulsed laser to the second region.

8. The exposure system according to claim 1, wherein The exposure system further has an inspection device that measures a critical dimension of an exposed semiconductor substrate on which the scan exposure is performed, The processor calculates each of the target values of the control parameters of the pulsed laser that converges the proximity effect characteristics to the proximity effect characteristics that differ from the reference within the allowable range, for each of the first region and the second region, in accordance with information of a reticle pattern of a reticle and a measurement result using the inspection device.

9. The exposure system according to claim 1, wherein The processor controls the output of the pulsed laser in accordance with a moving cumulative value of each of the target values of the control parameters of the pulsed laser that is exposed to the scan field of the semiconductor substrate.

10. The exposure system according to claim 9, wherein The control parameters include a moving cumulative value of at least one of a wavelength, a spectral linewidth, and a pulse energy.

11. The exposure system according to claim 9, wherein The processor calculates a target value of the control parameters of the next pulse so that each of the target values of the control parameters of the pulsed laser becomes a moving cumulative value, The laser device is controlled in a pulse unit in accordance with each of the calculated target values.

12. The exposure system according to claim 1, wherein The laser device has: a spectrum detector that measures a spectral waveform of the pulsed laser; and a light sensor that measures a pulse energy of the pulsed laser, The processor calculates a moving cumulative wavelength in accordance with the spectral waveform of the pulsed laser measured using the spectrum detector, The processor calculates a moving cumulative spectral linewidth in accordance with the spectral waveform of the pulsed laser measured using the spectrum detector, The processor calculates a cumulative value of a moving cumulative pulse energy in accordance with the pulse energy of the pulsed laser measured using the light sensor, The processor calculates a cumulative value of a moving cumulative pulse energy in accordance with the pulse energy of the pulsed laser measured using the light sensor, The processor writes the calculated values of the moving accumulated wavelength, the moving accumulated spectral line width, the moving accumulated pulse energy, and the respective data of the spectral waveform in a second file.

13. The exposure system according to claim 12, wherein The processor calculates a moving accumulated spectral waveform of the target from a control parameter of a target pulse laser, The processor calculates a target spectral waveform of the next pulse from the moving accumulated spectral waveform of the target and the data of the second file, and determines a target wavelength and a target spectral line width of the next pulse from the target spectral waveform, The processor determines a target pulse energy of the next pulse from the moving accumulated pulse energy of the target and the data of the second file.

14. The exposure system according to claim 1, wherein The laser device is an excimer laser device including an oscillator and an amplifier that amplifies a pulse laser output from the oscillator, The oscillator has a narrowband module.

15. The exposure system according to claim 1, wherein The laser device is an excimer laser device including an oscillator and an amplifier that amplifies a pulse laser output from the oscillator, The oscillator is a solid laser system using a distributed feedback type semiconductor laser.

16. The exposure system according to claim 1, wherein The proximity effect characteristic of the reference is a proximity effect characteristic of the exposure system that becomes the reference.

17. A laser control parameter generation method executed by a processor, wherein The laser control parameter is a control parameter of a pulse laser irradiated to a reticle of an exposure system that performs a scan exposure to a semiconductor substrate, the control parameter including at least one of a wavelength and a spectral line width, The laser control parameter generation method includes the steps of: The processor calculates proximity effect characteristics corresponding to respective regions of a first region and a second region of the reticle, the first region and the second region being scan regions within a scan field, the first region and the second region having different pattern forms; The processor determines target values of the control parameter of the pulse laser that exhibit proximity effect characteristics in which a difference from a proximity effect characteristic of a reference converges within an allowable range in the respective regions, from a result of the calculation; and The processor stores the determined target values of the control parameter in association with the respective regions in a file, the respective target values being different.

18. The laser control parameter generation method according to claim 17, wherein The processor calculates proximity effect characteristics corresponding to respective regions of a first region and a second region using a plurality of data including a parameter of an illumination optical system of the exposure system, a parameter of a projection optical system, a parameter of a resist applied to the semiconductor substrate, a reticle pattern of the reticle, and a control parameter of the pulse laser, The processor changes values of the control parameters of the pulsed laser, and performs the calculation of the proximity effect characteristics a plurality of times, thereby determining respective target values of the control parameters of the pulsed laser that result in proximity effect characteristics that converge on proximity effect characteristics of the reference within the allowable range.

19. The method of generating laser control parameters according to claim 17, wherein The method of generating laser control parameters further includes a step in which the processor receives a measurement result obtained by an inspection device that measures a critical dimension of an exposed semiconductor substrate on which the scan exposure has been performed, The processor calculates proximity effect characteristics corresponding to each of the first region and the second region based on the measurement result and information of a reticle pattern of the reticle.

20. The method of generating laser control parameters according to claim 17, wherein The proximity effect characteristics of the reference are proximity effect characteristics of an exposure system that is a reference.

21. A method of manufacturing electronic devices, wherein The method of manufacturing electronic devices includes a step of performing scan exposure of a photosensitive substrate by irradiating a pulsed laser to a reticle using an exposure system to manufacture electronic devices, The exposure system has: a laser device that outputs the pulsed laser; an illumination optical system that guides the pulsed laser to the reticle; a reticle stage that moves the reticle; and a processor that controls output of the pulsed laser from the laser device and movement of the reticle based on the reticle stage, The reticle has a first region and a second region that are scan regions within a scan field, The first region and the second region differ in pattern form, The processor instructs the laser device to output the pulsed laser corresponding to each of the first region and the second region based on proximity effect characteristics corresponding to each of the first region and the second region, so that the control parameters of the pulsed laser corresponding to each of the regions include at least one of wavelength and spectral line width, and each of the target values is different, so that the proximity effect characteristics converge on proximity effect characteristics of a reference within an allowable range.

22. The method of manufacturing electronic devices according to claim 21, wherein The proximity effect characteristics of the reference are proximity effect characteristics of an exposure system that is a reference. ​

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