Apparatus and method for vibration cancellation for laser wavelength and bandwidth stability

Abstract

Apparatus and method for reducing the impact of vibrations on components within a deep ultraviolet light source module. The components are provided with sensors (325, 335) for detecting the vibration waveform and actuators (320, 330) for applying a waveform opposite to, and thus cancelling, the vibration waveform. In addition to the application of active noise (vibration) cancellation, the vibration waveforms resulting from active vibration suppression are analyzed to identify residual vibrations, and the characteristics of the residual vibration cancellation waveform are determined.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0001] This application claims priority to U.S. Application No. 63 / 328,943, filed on April 8, 2022, entitled "APPARATUS FOR AND METHOD OF VIBRATION CANCELLATION FOR LASER WAVELENGTH AND BANDWIDTH STABILITY", which is hereby incorporated by reference in its entirety.

[0002]

[0002] The disclosed subject matter relates to a system in which several components of a laser system for performing a photolithography integrated circuit manufacturing process can benefit from the use of a vibration cancellation system and method. The disclosed subject matter relates, for example, to a deep ultraviolet ("DUV") laser line narrowing module ("LNM") having a center wavelength selection optical element that is movable or has some flexure upon attachment, or both.

Background Art

[0003]

[0003] Photolithography is a process of patterning a semiconductor circuit on a substrate such as a silicon wafer. A photolithography light source provides DUV light that is used to expose a photoresist on the wafer. The light source is often a laser source and the light is often a pulsed laser beam. The light beam passes through a beam delivery unit, then through a reticle or mask, and then is projected onto a prepared silicon wafer. In this way, the chip design is patterned on the photoresist, then the photoresist is etched and cleaned, and then this process is repeated.

[0004]

[0004] Many systems that generate a laser beam (such as a laser generation device) or use a laser beam (such as a photolithography system) have an optical train, which includes one or more optical components (mirrors, gratings, prisms, optical switches, filters, etc.) that are often included in a module. The optical components of the optical train reflect, process, filter, modify, focus, expand, etc., the laser beam, either wholly or in part, to obtain one or more desired laser beam outputs.

[0005]

[0005] One optical component within the optical train is a line narrowing package or line narrowing module, also known as an "LNP" or LNM. The line narrowing module is positioned and adapted to select a desired central wavelength around a narrow band of wavelengths, and the bandwidth of the narrow band is also carefully selected to be as narrow as possible, for example, for lithography applications where chromatic aberration of the lens of a scanning lithography photoresist exposure apparatus can be important. Also, the bandwidth is selected to be within a certain range, i.e., not too large and not too small, to enable optimization of the latest optical proximity effect correction techniques commonly used when preparing a mask such as a reticle, for example, for photolithography reasons.

[0006]

[0006] Also, it is well known that such an LNM can typically use a variety of different central wavelength selection optical elements in a distributed manner, and these optical elements can reflect the selected central wavelength and narrow band light back into the optical path of, for example, a laser oscillation resonance chamber, depending on some physical parameters of the LNM and the optical parameters and performance capabilities of the wavelength selection optical elements, such as dispersive optical elements.

[0007]

[0007] For the optical components within the LNM to function well, they must be practically isolated from external mechanical vibrations as much as possible. These vibrations can be regarded as acoustic vibrations or noise, and thus reducing such vibrations can be regarded as noise control or noise cancellation. These vibrations can cause instability in both or either of the central wavelength and / or bandwidth if not controlled. The vibration modes can be amplified by the resonance conditions of various laser structures including the LNM and its components.

[0008]

[0008] As a specific example, the LNM can include one or more prisms that can be mounted within the LNM using flexure mounting. Prisms mounted in this way are susceptible to vibrations, which can be harmful to central wavelength control and / or stability and may also have an adverse effect on bandwidth control. There are multiple paths through which vibrations can reach the LNM, including those passing through the bellows used to surround the actuator arm connected to the components inside the LNM. Vibrations can also reach the LNM through connections to the laser chassis including post connections.

[0009]

[0009] A passive vibration control system such as a vibration damping mechanism may be used to reduce the impact of vibrations on the positioning of the prism. The passive isolation system still allows some vibrations from the main chassis and chamber to affect the LNM. It is also known to use an active vibration / noise control system that detects the waveform of the incident noise or vibration and generates a cancellation waveform to cancel the incident waveform.

[0010]

[0010] Improved wavelength and bandwidth stability devices and methods are the subject of embodiments of the present specification.

Summary of the Invention

[0011]

[0011] The following presents a concise overview of one or more embodiments to provide a basic understanding of the present invention. This overview is not an extensive survey of all possible embodiments, nor is it intended to identify key or critical elements of all embodiments or to describe in detail the scope of any or all embodiments. Its sole purpose is to present, in a rationalized form, some concepts of one or more embodiments as a prelude to the more detailed description that follows.

[0012]

[0012] According to one aspect of an embodiment, a vibration isolation device for a module of a lithography system is disclosed. The module has a chassis, and the vibration isolation device includes a first piezoelectric mass member mechanically coupled to the chassis and adapted to be accelerated in a first direction by a vibration waveform that vibrates the chassis and generate a signal indicative of a component of the vibration waveform in the first direction, a controller arranged to receive the signal and adapted to generate a first vibration suppression waveform based at least in part on the signal, and a second piezoelectric mass member mechanically coupled to the chassis and arranged to receive the first vibration suppression waveform and adapted to apply a first vibration isolation force to the chassis in the first direction in accordance with the first vibration suppression waveform.

[0013]

[0013] The vibration isolation device may further include a third piezoelectric mass member mechanically coupled to the chassis and adapted to be accelerated in a second direction by a vibration waveform that vibrates the chassis and generate a second signal indicative of a component of the vibration waveform in the second direction, a controller arranged to receive the second signal and adapted to generate a second vibration suppression waveform based at least in part on the second signal, and a fourth piezoelectric mass member mechanically coupled to the chassis and arranged to receive the second vibration suppression waveform and adapted to apply a second vibration isolation force to the chassis in the second direction in accordance with the second vibration suppression waveform.

[0014]

[0014] The first direction and the second direction may be substantially orthogonal.

[0015] The vibration isolation device may further include a fifth piezoelectric mass member mechanically coupled to the chassis and adapted to be accelerated in a third direction by a vibration waveform that vibrates the chassis and generate a third signal indicative of a component of the vibration waveform in the third direction, a controller disposed to receive the third signal and adapted to generate a third vibration suppression waveform based at least in part on the third signal, and a sixth piezoelectric mass member mechanically coupled to the chassis and disposed to receive the third vibration suppression waveform and adapted to apply a third vibration isolation force to the chassis in the third direction in accordance with the third vibration suppression waveform.

[0016]

[0016] The first direction, the second direction, and the third direction may be substantially orthogonal to each other.

[0017]

[0017] The controller may be adapted to analyze a residual vibration component of a signal present while the second piezoelectric mass member applies a vibration isolation force and to modify the first vibration suppression waveform to reduce the residual vibration component. Each of the piezoelectric mass members may include a piezoelectric crystal and a vibration mass.

[0018]

[0018] According to another aspect of an embodiment, a vibration isolation device for a module of a lithography system is disclosed, the module having a chassis, the vibration isolation device including a first sensor mechanically coupled to the chassis and arranged to detect a first direction component of a vibration waveform in a first direction and generate a first output indicative of the first direction component, a second sensor mechanically coupled to the chassis and arranged to detect a second direction component of a vibration waveform in a second direction different from the first direction and generate a second output indicative of the second direction component, and a cancellation waveform generator arranged to receive the first output and the second output and generate a first vibration cancellation waveform for the first direction based at least in part on the first output and a second vibration cancellation waveform for the second direction based at least in part on the second output.

[0019]

[0019] The apparatus also includes a first actuator mechanically coupled to the chassis and arranged to receive a first vibration cancellation waveform and generate a first cancellation vibration corresponding to the first vibration cancellation waveform in a first direction, and a second actuator mechanically coupled to the chassis and arranged to receive a second vibration cancellation waveform and generate a second cancellation vibration corresponding to the second vibration cancellation waveform in a second direction.

[0020]

[0020] The vibration isolation system further includes a residual vibration cancellation waveform generator arranged to receive a first output and a second output, identify a first residual vibration waveform for the first direction based at least in part on the first output while the first cancellation vibration is being generated, generate a first residual vibration suppression waveform based at least in part on the first residual vibration waveform, and add the first residual vibration waveform to the first vibration cancellation waveform, and identify a second residual vibration waveform for the second direction based at least in part on the second output while the second cancellation vibration is being generated, generate a second residual vibration suppression waveform based at least in part on the second residual vibration waveform, and add the second residual vibration waveform to the second vibration cancellation waveform.

[0021]

[0021] The first sensor may comprise a first sensor piezoelectric transducer, and the second sensor may comprise a second sensor piezoelectric transducer.

[0022]

[0022] The first sensor piezoelectric transducer and the second sensor piezoelectric transducer may each comprise a piezoelectric crystal and a vibration mass. The first actuator may comprise a first piezoelectric transducer, and the second actuator may comprise a second piezoelectric transducer. The first piezoelectric transducer and the second piezoelectric transducer may each comprise a piezoelectric crystal and a vibration mass. The module may comprise a line narrowing module.

[0023]

[0023] The residual vibration cancellation waveform generator may be adapted to identify a first residual vibration waveform by analyzing the wavelength of the first output with wavelength sigma and to identify a second residual vibration waveform by analyzing the wavelength of the second output with wavelength sigma.

[0024]

[0024] The first direction may be orthogonal to the second direction.

[0025]

[0025] The apparatus may further include a third sensor mechanically coupled to the chassis and arranged to detect a third direction component of a vibration waveform in a third direction different from the first and second directions and to generate a third output indicative of the third direction component, and a cancellation waveform generator arranged to receive the third output and to generate a third vibration cancellation waveform for the third direction based at least in part on the third output. The apparatus may also include a third actuator mechanically coupled to the chassis and arranged to receive the third vibration cancellation waveform and to generate a third cancellation vibration corresponding to the third vibration cancellation waveform in the third direction, and a residual vibration cancellation waveform generator arranged to receive the third output and to identify a third residual vibration waveform for the third direction based at least in part on the third output while the third cancellation vibration is being generated and to generate a third residual vibration suppression waveform based at least in part on the third residual vibration waveform and to add the third residual vibration waveform to the third vibration cancellation waveform.

[0026] According to another aspect of an embodiment, a vibration isolation method for a module for a lithography system is disclosed, the module having a chassis, the vibration isolation method comprising detecting a first direction component of a vibration waveform in a first direction and generating a first output indicative of the first direction component; detecting a second direction component of a vibration waveform in a second direction different from the first direction and generating a second output indicative of the second direction component; generating a first vibration cancellation waveform for the first direction based at least in part on the first output and a second vibration cancellation waveform for the second direction based at least in part on the second output; generating a first cancellation vibration in the first direction corresponding to the first vibration cancellation waveform; and generating a second cancellation vibration in the second direction corresponding to the second vibration cancellation waveform.

[0027] The method also includes identifying, while the first cancellation vibration is being generated, a first residual vibration waveform for the first direction based at least in part on the first output and generating a first residual vibration suppression waveform based at least in part on the first residual vibration waveform, adding the first residual vibration waveform to the first vibration cancellation waveform; and identifying, while the second cancellation vibration is being generated, a second residual vibration waveform for the second direction based at least in part on the second output and generating a second residual vibration suppression waveform based at least in part on the second residual vibration waveform, adding the second residual vibration waveform to the second vibration cancellation waveform.

[0028] Detecting a first direction component of a vibration waveform in a first direction and generating a first output indicative of the first direction component may be implemented using a first piezoelectric transducer, and detecting a second direction component of a vibration waveform in a second direction and generating a second output indicative of the second direction component is implemented using a second piezoelectric transducer.

[0029] Generating the first cancellation vibration in the first direction may be implemented using a first piezoelectric transducer, and generating the second cancellation vibration in the second direction is implemented using a second piezoelectric transducer.

[0030] Identifying the first residual vibration waveform may include analyzing the wavelength of the first output with a wavelength sigma, and identifying the second residual vibration waveform may include analyzing the wavelength of the second output with a wavelength sigma.

[0031] The first direction may be orthogonal to the second direction.

[0032] The method may further include detecting a third direction component of the vibration waveform in a third direction different from the first and second directions and generating a third output indicating the third direction component, generating a third vibration cancellation waveform for the third direction at least partially based on the third output, and generating a third cancellation vibration corresponding to the third vibration cancellation waveform in the third direction. The method may further include identifying a third residual vibration waveform for the third direction at least partially based on the third output while the third cancellation vibration is being generated, and generating a third residual vibration suppression waveform at least partially based on the third residual vibration waveform and adding the third residual vibration waveform to the third vibration cancellation waveform.

[0033] Further embodiments, features, and advantages of the subject matter of the present disclosure, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings.

Brief Description of the Drawings

[0034] The accompanying drawings, which are incorporated herein and form a part of this specification, illustrate the invention and, together with the description, further function to clarify the principles of the invention and to enable one skilled in the art to make and use the invention.

[0035]

Figure 1

[0035] This is a schematic diagram of the overall broad concept of a photolithography system, not to scale.

Figure 2

[0036] This is a schematic diagram of the overall broad concept of an illumination system that can be used in the photolithography system of FIG. 1, not to scale.

Figure 3

[0037] This is a front view of an example of an optical module including a sensor and actuator pair according to an aspect of an embodiment.

Figure 4

[0038] This is an end view of the optical module of FIG. 3.

Figure 5

[0039] This is a functional block diagram of a system for reducing vibration in an optical module according to an aspect of an embodiment.

Figure 6

[0040] This is a graph of an example of the wavelength spectrum of vibration in an optical module.

Figure 7

[0041] This is a functional block diagram of another system for reducing vibration in an optical module according to an aspect of an embodiment.

Figure 8

[0042] This is a flowchart of a method for reducing vibration in an optical module according to an aspect of an embodiment.

[0036]

[0043] Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, will be described in detail below with reference to the accompanying drawings. It should be noted that the scope of the present invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the art based on the teachings presented herein.

DETAILED DESCRIPTION OF THE INVENTION

[0037]

[0044] Next, various embodiments will be described with reference to the drawings. Throughout the text, the same reference numerals are used to refer to the same elements. In the following description, for the purpose of promoting a complete understanding of one or more embodiments, many specific details are set forth for illustrative purposes. However, it will be apparent that in some or all cases, any of the embodiments described hereinafter can be practiced without adopting the specific design details described hereinafter. In other instances, well-known structures and devices are shown in block diagram form to facilitate the description of one or more embodiments. This summary is not an extensive overview of all contemplated embodiments, nor is it intended to pick out key or critical elements of all embodiments or to delineate in detail the scope of any or all embodiments.

[0038]

[0045] Systems as described herein can provide benefits in a wide range of applications and examples. To facilitate the description, a specific non-limiting example is given. One such application is in semiconductor photolithography. FIG. 1 shows a photolithography system 100 that includes an illumination system 105. As will be described more fully below, the illumination system 105 includes a light source that generates a pulsed light beam 110 and directs it towards a photolithography exposure apparatus or scanner 115 that patterns microelectronic features on a wafer 120. The wafer 120 is placed on a wafer table 125 that is connected to a positioner 127 that is constructed to hold the wafer 120 and configured to accurately position the wafer 120 according to certain parameters.

[0039]

[0046] The pulsed light beam 110 may have a wavelength in the DUV range, for example, a wavelength of 248 nanometers (nm) or 193 nm. The scanner 115 includes, for example, an optical arrangement 117 having one or more condenser lenses, a mask, and an objective lens arrangement. The mask is movable along one or more directions, such as along the optical axis of the pulsed light beam 110 or within a plane perpendicular to the optical axis. The objective lens arrangement includes a projection lens and enables image transfer from the mask to the photoresist on the wafer 120. The illumination system 105 adjusts the range of angles at which the pulsed light beam 110 is incident on the mask. The illumination system 105 also homogenizes (makes uniform) the intensity distribution of the pulsed light beam 110 across the entire mask.

[0040]

[0047] The scanner 115 can include, among other features, a lithography controller 130 that controls how a layer is printed on the wafer 120. The lithography controller 130 may include a memory that stores information such as a process recipe that determines parameters including the length of exposure to the wafer 120 based on, for example, the mask used and other factors that affect the exposure. During lithography, a burst of pulses of the pulsed light beam 110 illuminates the same area of the wafer 120 to constitute the exposure dose.

[0041]

[0048] The photolithography system 100 also preferably includes a control system 135. Generally, the control system 135 includes one or more of digital electronic circuits, computer hardware, firmware, and software. The control system 135 may be integrated or may be partially or fully distributed throughout the photolithography system 100.

[0042]

[0049] FIG. 2 shows a pulsed laser source that generates a pulsed laser beam as the optical beam 110 as an example of the illumination system 105. Although FIG. 2 shows a two-chamber laser system as a non-limiting example, it will be understood that the principles disclosed herein are equally applicable to a single-chamber laser system or a laser system having more than two chambers. The gas discharge laser system may include, for example, a solid or gas discharge master oscillator ("MO") seed laser system 140, an amplification stage, such as a power ring amplifier ("PRA") stage 145, relay optics 150, and a laser system output subsystem 160. The seed system 140 may include, for example, an MO chamber 165 that includes a pair of electrodes 167 and 168.

[0043]

[0050] The MO seed laser system 140 may also include a master oscillator output coupler ("MO OC") 175 that may include a partially reflective mirror, forming an MO 165 with an oscillator cavity defined by a reflection grating (not shown) within the LNM 170, and the MO oscillates to form a seed laser output pulse. The MO seed laser system 140 may also include a line center analysis module ("LAM") 180. The MO wavefront engineering box ("WEB") 185 may serve to redirect the output of the MO seed laser system 140 towards the amplification stage 145 and may include, for example, a multi-prism beam expander (not shown) and an optical delay path (not shown).

[0044]

[0051] The amplification stage 145 may include, for example, a PRA laser oscillation chamber 200, which may also be an oscillator formed by, for example, a seed beam incidence and an output coupling optical system (not shown) incorporated into the PRA WEB 210. The beam may be redirected by a beam reverser ("BR") 220 to pass back through the gain medium within the chamber 200. The PRA WEB 210 may incorporate a partially reflective input / output coupler (not shown), a maximum reflection mirror for the nominal operating wavelength (e.g., around 193 nm for an ArF system), and one or more prisms. The PRA laser oscillation chamber 200 may also include a pair of electrodes 207 and 208.

[0045]

[0052] The bandwidth analysis module ("BAM") 230 receives the pulsed output laser beam from the PRA laser oscillation chamber 200 and may pick off a part of the light beam for metrology purposes, for example, to measure the output bandwidth and pulse energy. The pulsed laser output beam then passes through the PRA WEB 210 and travels to the optical pulse stretcher ("OPuS") 240 and an auto shutter, which may also be a location with a pulse energy meter, in this case the composite auto shutter metrology module ("CASMM") 250. One purpose of the OPuS 240 may be, for example, to convert a single output laser pulse into a pulse train. The secondary pulses created from the original single output pulse may be delayed relative to each other. By dispersing the original laser pulse energy into a train of secondary pulses, the effective pulse length of the laser can be increased while reducing the peak pulse intensity. Therefore, the OPuS 240 may be arranged to receive the laser beam from the PRA WEB 210 and direct its output towards the CASMM 250.

[0046]

[0053] The PRA laser oscillation chamber 200 and the MO 165 are configured as chambers in which a discharge between electrodes causes a laser oscillation gas discharge in the laser oscillation gas, creating an inverted distribution of high-energy molecules containing, for example, Ar, Kr, F 2 , and / or Xe and generating relatively broadband radiation. This radiation can be line-narrowed to a relatively ultra-narrow bandwidth and center wavelength selected in the LNM 170.

[0047]

[0054] A system as described above may be conceptualized as a collection of several modules, each of which may include one or more optical components such as prisms and folding mirrors.

[0048]

[0055] As described above, a system for preventing vibrations from degrading the performance of components such as prisms and gratings within an LNM may include passive measures such as dampers and active measures that set a waveform opposite to the waveform of the vibrations. However, even when such a system is used, residual vibrations that may still degrade the operation remain.

[0049]

[0056] According to one aspect of an embodiment, disclosed herein is an anti-vibration system for an optical component, wherein vibrations are measured in at least two dimensions by a corresponding number of sensors, and residual vibrations that persist even after active noise cancellation are identified and neutralized by a corresponding number of actuators. According to one aspect of an advantageous embodiment, three sensor-actuator pairs operating in directions perpendicular to each other may be present to reduce crosstalk. In the following example, the three directions are labeled X, Y, and Z. It will be understood that the directions X, Y, and Z are not an arbitrary external absolute coordinate system, but are selected to coincide with the axes of the LNM. It will also be understood that the axes do not have to coincide exactly. Also, the term "direction" in this context refers to movement in both the forward and backward directions in that direction. For example, "in the X direction" refers to movement in both the +X and -X directions. Similarly, for example, "movement in the first direction" refers to movement in both the forward and backward directions in that direction.

[0050]

[0057] Thus, referring now to FIG. 3, LNM300 is shown as an example of an optical component of a laser system. The chassis 305 of the LNM300 is mechanically coupled by posts 305 and bellows 310 to a laser system (not shown in FIG. 3) of which it is a part. The LNM300 shown in FIG. 3 also includes three pairs of piezoelectric ("PZT") actuators and PZT sensors. In this example, the actuators are implemented as PZT actuators, but one of ordinary skill in the art will readily understand that any suitable type of actuator may be used. Thus, the term "actuator" in this context should be broadly construed to include any type of device or system capable of generating a mechanical force in response to a control signal. Similarly, the term "sensor" in this context should be broadly construed to include any type of device or system capable of converting a mechanical force into a signal.

[0051]

[0058] Thus, a first PZT actuator 320 and a first PZT sensor 325 are present. The first PZT actuator 320 is mechanically coupled to one end of the chassis 305 at a first location, and the PZT sensor 325 is installed and mechanically coupled to another end of the chassis 305 at a second location displaced in the X direction from the first location. Similarly, the arrangement of FIG. 3 also includes a PZT actuator 330 and a PZT sensor 335 displaced from each other in the Y direction. The arrangement shown in FIG. 3 also includes a PZT actuator 340 displaced from a PZT sensor 345 (shown in FIG. 4 which is a 90° rotation of the LNM300 of FIG. 3 about the Y axis) displaced from each other in the Z direction.

[0052]

[0059] The arrangement shown in the figures detects and generates vibrations in three orthogonal dimensions, but one of ordinary skill in the art will readily understand that for some applications, an arrangement that detects and generates vibrations in only two dimensions may be sufficient. One of ordinary skill in the art will also understand that the directions need not necessarily be orthogonal, but as described above, there is an advantage in reducing crosstalk in a configuration where the sensor / actuator pairs are arranged to detect and generate orthogonal vibrations.

[0053]

[0060] According to another aspect of an embodiment, each of the PZT elements includes a vibrating mass and a PZT crystal. Such a combination is called a piezoelectric mass member. Thus, the PZT actuator 320 includes a mass 323 and a PZT crystal 322. The PZT sensor 325 includes a mass 327 and a PZT crystal 328. The PZT actuator 330 includes a mass 332 and a PZT part 333. On the other hand, the PZT sensor 335 is composed of a PZT crystal and uses the mass of the post 305 as the vibrating mass. The mass 342 of the PZT actuator 340 is visible in FIG. 3. The PZT crystal 344 is visible in FIG. 4. The PZT sensor 345 composed of a mass 347 and a PZT crystal 349 is also visible in FIG. 4. The mass is provided within the sensor, for example, when the sensor senses vibrations, it applies a load to the PZT crystal.

[0054]

[0061] The PZT 335 sensor at the post 305 below the LNM300 and the PZT actuator 330 above the LNM300, for example, serve to actively cancel noise in the Y direction. One of ordinary skill in the art will understand that the PZT actuator 330 need not be installed above the LNM300, but instead can be installed below the LNM300, close to the PZT sensor 335, to minimize higher-order vibration modes. The same applies to the other two sensor / actuator pairs.

[0055]

[0062] According to another aspect of an embodiment, the sensor is used to detect the waveform of the vibration of the LNM300 for the purpose of determining parameters of the canceling active signal that counteracts the vibration, such as frequency / wavelength, amplitude, phase, and directionality. In some embodiments, the measurements are obtained while the laser is operating. According to another aspect of an embodiment, the resulting waveform (i.e., the vibration signal actively canceled) is further analyzed to identify the frequency of the residual vibration (i.e., the noise that continues to exist despite the active cancellation measures). The results of this analysis are used to develop one or more signal parameters selected to minimize the residual vibration.

[0056]

[0063] Generally, the correct phase is very close to 180 degrees. For example, the LNM chassis 305 can be mainly composed of aluminum. The speed of sound in aluminum is relatively high, i.e., about 6000 meters per second, and the wavelength of the vibration of the LNM chassis 305 is generally within the acoustic range. Therefore, the wavelengths of these sound waves are much larger than the size of the LNM300, which makes the correct phase of the residual opposing waveform about 180 degrees even when the locations of the actuator and the sensor are not the same.

[0057]

[0064] In other words, in addition to generating the opposing waveform for active noise cancellation, according to one aspect of an embodiment, the standard deviation or sigma of the wavelength spectrum obtained when the laser vibration is actively suppressed is analyzed for the residual vibration frequency. This is referred to herein as analyzing with wavelength sigma. Then, signals opposite to these residual vibration frequencies are added to the active noise suppression signal. The wavelength / frequency, phase, amplitude, and direction of these residual vibration prevention signals are selected to minimize the residual vibration.

[0058]

[0065] The signal opposite to the residual vibration frequency can be generated by performing an amplitude sweep for the identified residual frequencies and their harmonics in two or three directions while the laser is emitting (i.e., changing the amplitude while keeping the frequency constant for each sweep) to minimize the residual frequency. The minimization can be carried out using optimization techniques such as gradient descent optimization where the cost function is a function describing the vibration and the first derivative of the cost function is used to find the minimum value. The minimization can be carried out using a heuristic method or even using a system that uses a feedforward algorithm for more effective cancellation.

[0059]

[0066] FIG. 5 is a functional block diagram of a vibration isolation system according to an aspect of an embodiment. As shown in FIG. 5, the outputs of the X-direction PZT sensor 325, the Y-direction PZT sensor 335, and the Z-direction PZT sensor 345 are each supplied as inputs to the waveform analysis and generation module 500. The waveform analysis and generation module 500 uses the inputs from the sensors to determine one or more of the parameters, such as the amplitude, frequency, direction, and phase of the waveform of the active noise cancellation signal. The waveform analysis and generation module 500 also uses these inputs to analyze the spectrum of the vibrations that still exist despite the application of the active noise cancellation signal at the sigma wavelength. In other words, the sigma of the wavelength is analyzed for vibration frequencies that may still be affecting the stability of the wavelength and bandwidth. The waveform analysis and generation module 500 then identifies these residual vibrations and determines the parameters of the signals to be applied to the X, Y, and Z PZT actuators 320, 330, and 340, respectively, to reduce the residual vibrations.

[0060]

[0067] Figure 6 is a graph showing several principles for analyzing signals at the sigma wavelength. The graph of Figure 6 plots the wavelength of vibrations in any unit against the intensity of the vibrations at that wavelength, also in any unit. This plot generally takes the form of a Gaussian curve or bell-shaped curve. As is well known, the horizontal distance σ in both directions from the center line 600 is the standard deviation of this plot and captures approximately 68% of the area under the curve. According to one aspect of one embodiment, wavelengths in this range are identified to find and identify residual vibrations.

[0061]

[0068] Figure 7 is also a functional block diagram of a vibration isolation system according to another aspect of one embodiment. In the arrangement shown in Figure 7, the signal from the X-direction sensor 325 is supplied to both the active noise cancellation waveform generator 700 and the residual cancellation waveform generator 710. The signal from the Y-direction sensor 335 is also supplied to both of these waveform generators, and the same is true for the signal from the Z-direction sensor 345. The active noise cancellation waveform generator 700 uses the input to generate active noise cancellation waveforms for each direction, and those noise cancellation waveforms are supplied to the addition node 720. At the same time, the residual cancellation waveform generator 710 analyzes the input received from the sensors at the sigma wavelength to determine the wavelength of the residual vibrations of the detected vibration signal. One of these signals for each direction is also supplied to the addition node 720. The addition node 720 adds the signals from the active noise cancellation waveform generator 700 and the residual cancellation waveform generator 710 for each direction, and then supplies, as outputs, a signal to the actuator 320, a signal to the actuator 330, and a signal to the actuator 340, respectively.

[0062]

[0069] FIG. 8 is a flowchart of a method for suppressing vibration according to an aspect of an embodiment. In step S10, active vibration cancellation is applied as described above. Next, in step S20, the waveform of the resulting vibration is analyzed with a wavelength sigma to determine the waveform of the residual vibration. In step S30, the residual vibration cancellation waveform is determined. In other words, parameters such as the phase and direction of the residual vibration cancellation waveform are determined. In step S40, the residual cancellation waveform is applied to a PZT actuator that is mechanically coupled to an object for which vibration suppression is desired, for example, an LNM. In the method described in relation to FIG. 8, the residual waveform is determined after the active vibration cancellation waveform is applied, but those skilled in the art will readily understand that steps S10 and S20 can occur simultaneously.

[0063]

[0070] Part of the above description relates to functional block diagrams, where some functions are assigned to some blocks and other functions are assigned to other blocks. It will be understood that the division and assignment between blocks are arbitrary and that different divisions and assignments are possible as long as the overall function is performed as described above.

[0064]

[0071] The above description includes examples of multiple embodiments. Of course, it is not possible to describe all possible combinations of components or methodologies for the purpose of explaining these embodiments, but those skilled in the art will recognize that many further combinations and permutations of the elements of the various embodiments are possible based on this disclosure. Accordingly, the described embodiments are intended to represent and disclose all such changes, modifications, and variations that fall within the spirit and scope of the appended claims.

[0065]

[0072] Furthermore, since the term "comprising" is to be construed as a transitional term when used in a claim, such a term is intended to be as inclusive as the term "includes" as long as the term "includes" is used in either the detailed description or the claims. Also, although multiple elements of the described aspects and / or embodiments may be described or claimed in the singular, they are considered to be plural unless a limitation to the singular is explicitly stated. Additionally, all or part of any aspect and / or embodiment may be utilized with all or part of any other aspect and / or embodiment unless otherwise specified.

[0066]

[0073] The embodiments can be further described using the following clauses. 1. A vibration isolation device for a module of a lithography system, the module having a chassis, the vibration isolation device comprising: a first piezoelectric mass member mechanically coupled to the chassis and adapted to be accelerated in a first direction by a vibration waveform that vibrates the chassis and to generate a signal indicative of a component of the vibration waveform in the first direction; a controller arranged to receive the signal and adapted to generate a first vibration suppression waveform based at least in part on the signal; a second piezoelectric mass member mechanically coupled to the chassis and arranged to receive the first vibration suppression waveform and adapted to apply a first vibration isolation force to the chassis in the first direction in accordance with the first vibration suppression waveform; a vibration isolation device comprising the above. 2. A third piezoelectric mass member mechanically coupled to the chassis and adapted to be accelerated in a second direction by a vibration waveform that vibrates the chassis and to generate a second signal indicative of a component of the vibration waveform in the second direction; a controller arranged to receive the second signal and adapted to generate a second vibration suppression waveform based at least in part on the second signal; A fourth piezoelectric mass member that is mechanically coupled to the chassis and is arranged to receive a second vibration suppression waveform, and is adapted to apply a second anti-vibration force to the chassis in a second direction according to the second vibration suppression waveform. The anti-vibration device according to clause 1, further comprising . 3. The anti-vibration device according to clause 2, wherein the first direction and the second direction are substantially orthogonal. 4. A fifth piezoelectric mass member that is mechanically coupled to the chassis, is accelerated in a third direction by a vibration waveform that vibrates the chassis, and is adapted to generate a third signal indicating a component of the vibration waveform in the third direction. A controller that is arranged to receive the third signal and is adapted to generate a third vibration suppression waveform based at least in part on the third signal. A sixth piezoelectric mass member that is mechanically coupled to the chassis and is arranged to receive the third vibration suppression waveform, and is adapted to apply a third anti-vibration force to the chassis in the third direction according to the third vibration suppression waveform. The anti-vibration device according to clause 3, further comprising . 5. The anti-vibration device according to clause 4, wherein the first direction, the second direction, and the third direction are substantially orthogonal to each other. 6. The controller of the anti-vibration device according to clause 1 is adapted to analyze a residual vibration component of a signal that exists while the second piezoelectric mass member applies an anti-vibration force, and to modify the first vibration suppression waveform to reduce the residual vibration component. 7. Each of the piezoelectric mass members of the anti-vibration device according to clause 1 includes a piezoelectric crystal and a vibration mass. 8. An anti-vibration device for a module of a lithography system, the module having a chassis, the anti-vibration device comprising: A first sensor that is mechanically coupled to the chassis and is arranged to detect a first direction component of a vibration waveform in a first direction and generate a first output indicating the first direction component. A second sensor that is mechanically coupled to the chassis and is arranged to detect a second direction component of a vibration waveform in a second direction different from the first direction and generate a second output indicating the second direction component. An apparatus configured to receive a first output and a second output and generate a first vibration cancellation waveform in a first direction based at least in part on the first output and a second vibration cancellation waveform in a second direction based at least in part on the second output. A first actuator mechanically coupled to the chassis and configured to receive the first vibration cancellation waveform and generate a first cancellation vibration corresponding to the first vibration cancellation waveform in the first direction. A second actuator mechanically coupled to the chassis and configured to receive the second vibration cancellation waveform and generate a second cancellation vibration corresponding to the second vibration cancellation waveform in the second direction. Comprising The vibration isolation system further comprises An apparatus configured to receive the first output and the second output During generation of the first cancellation vibration, identify a first residual vibration waveform in the first direction based at least in part on the first output, generate a first residual vibration suppression waveform based at least in part on the first residual vibration waveform, and add the first residual vibration waveform to the first vibration cancellation waveform. During generation of the second cancellation vibration, identify a second residual vibration waveform in the second direction based at least in part on the second output, generate a second residual vibration suppression waveform based at least in part on the second residual vibration waveform, and add the second residual vibration waveform to the second vibration cancellation waveform. A residual vibration cancellation waveform generator A vibration isolation apparatus comprising. 9. The apparatus of clause 8, wherein the first sensor comprises a first sensor piezoelectric transducer and the second sensor comprises a second sensor piezoelectric transducer. 10. The apparatus of clause 9, wherein the first sensor piezoelectric transducer and the second sensor piezoelectric transducer each comprise a piezoelectric crystal and a vibration mass. 11. The apparatus of clause 8, wherein the first actuator comprises a first piezoelectric transducer and the second actuator comprises a second piezoelectric transducer. 12. The apparatus of clause 11, wherein the first piezoelectric transducer and the second piezoelectric transducer each comprise a piezoelectric crystal and a vibrating mass. 13. The apparatus of clause 8, wherein the module comprises a line narrowing module. 14. The apparatus of clause 8, wherein the residual vibration cancellation waveform generator is adapted to identify a first residual vibration waveform by analyzing the wavelength of the first output with wavelength sigma and to identify a second residual vibration waveform by analyzing the wavelength of the second output with wavelength sigma. 15. The apparatus of clause 8, wherein the first direction is orthogonal to the second direction. 16. A third sensor mechanically coupled to the chassis and arranged to detect a third direction component of a vibration waveform in a third direction different from the first and second directions and to generate a third output indicative of the third direction component; A cancellation waveform generator arranged to receive the third output and to generate a third vibration cancellation waveform for the third direction at least partially based on the third output; A third actuator mechanically coupled to the chassis and arranged to receive the third vibration cancellation waveform and to generate a third cancellation vibration corresponding to the third vibration cancellation waveform in the third direction; Arranged to receive the third output, A residual vibration cancellation waveform generator adapted to identify a third residual vibration waveform for the third direction at least partially based on the third output while the third cancellation vibration is being generated and to generate a third residual vibration suppression waveform at least partially based on the third residual vibration waveform and to add the third residual vibration waveform to the third vibration cancellation waveform; and further comprising; The apparatus of clause 8. 17. An anti-vibration method for a module for a lithography system, the module having a chassis, the anti-vibration method comprising: Detecting a first direction component of a vibration waveform in a first direction and generating a first output indicative of the first direction component; Detecting a second direction component of a vibration waveform in a second direction different from the first direction and generating a second output indicative of the second direction component; Generating a first vibration cancellation waveform for the first direction based at least in part on the first output and generating a second vibration cancellation waveform for the second direction based at least in part on the second output; Generating a first cancellation vibration in the first direction corresponding to the first vibration cancellation waveform; Generating a second cancellation vibration in the second direction corresponding to the second vibration cancellation waveform; Identifying a first residual vibration waveform for the first direction based at least in part on the first output while the first cancellation vibration is being generated, generating a first residual vibration suppression waveform based at least in part on the first residual vibration waveform, and adding the first residual vibration waveform to the first vibration cancellation waveform; Identifying a second residual vibration waveform for the second direction based at least in part on the second output while the second cancellation vibration is being generated, generating a second residual vibration suppression waveform based at least in part on the second residual vibration waveform, and adding the second residual vibration waveform to the second vibration cancellation waveform; A vibration isolation method comprising the above. 18. The method of clause 17, wherein detecting a first direction component of a vibration waveform in a first direction and generating a first output indicative of the first direction component is performed using a first piezoelectric transducer, and detecting a second direction component of a vibration waveform in a second direction and generating a second output indicative of the second direction component is performed using a second piezoelectric transducer. 19. The method of clause 17, wherein generating a first cancellation vibration in the first direction is performed using a first piezoelectric transducer, and generating a second cancellation vibration in the second direction is performed using a second piezoelectric transducer. The method of clause 17, wherein identifying the first residual vibration waveform comprises analyzing the wavelength of the first output with a wavelength sigma, and identifying the second residual vibration waveform comprises analyzing the wavelength of the second output with a wavelength sigma. The method of clause 17, wherein the first direction is orthogonal to the second direction. 22. Detecting a third direction component of a vibration waveform in a third direction different from the first direction and the second direction to generate a third output indicating the third direction component; Generating a third vibration cancellation waveform for the third direction at least partially based on the third output; Generating a third cancellation vibration corresponding to the third vibration cancellation waveform in the third direction; Identifying a third residual vibration waveform for the third direction at least partially based on the third output while the third cancellation vibration is being generated; Generating a third residual vibration suppression waveform at least partially based on the third residual vibration waveform and adding the third residual vibration waveform to the third vibration cancellation waveform; The method of clause 17, further comprising.

[0067]

[0074] The above-described embodiments and other embodiments are within the scope of the following claims.

Claims

1. A vibration isolation device for a module of a lithography system, wherein the module has a chassis, and the vibration isolation device comprises: a first piezoelectric mass member mechanically coupled to the chassis and adapted to be accelerated in a first direction by a vibration waveform that vibrates the chassis and to generate a signal indicative of a component of the vibration waveform in the first direction; a controller arranged to receive the signal and adapted to generate a first vibration suppression waveform based at least in part on the signal; a second piezoelectric mass member mechanically coupled to the chassis and arranged to receive the first vibration suppression waveform, and adapted to apply a first vibration isolation force to the chassis in the first direction in accordance with the first vibration suppression waveform; A vibration isolation device comprising the above.

2. a third piezoelectric mass member mechanically coupled to the chassis and adapted to be accelerated in a second direction by the vibration waveform that vibrates the chassis and to generate a second signal indicative of a component of the vibration waveform in the second direction; the controller arranged to receive the second signal and adapted to generate a second vibration suppression waveform based at least in part on the second signal; a fourth piezoelectric mass member mechanically coupled to the chassis and arranged to receive the second vibration suppression waveform, and adapted to apply a second vibration isolation force to the chassis in the second direction in accordance with the second vibration suppression waveform; The vibration isolation device according to claim 1, further comprising the above.

3. The vibration isolation device according to claim 2, wherein the first direction and the second direction are substantially orthogonal.

4. a fifth piezoelectric mass member mechanically coupled to the chassis and adapted to be accelerated in a third direction by the vibration waveform that vibrates the chassis and to generate a third signal indicative of a component of the vibration waveform in the third direction; the controller arranged to receive the third signal and adapted to generate a third vibration suppression waveform based at least in part on the third signal; a sixth piezoelectric mass member mechanically coupled to the chassis and arranged to receive the third vibration suppression waveform, and adapted to apply a third vibration isolation force to the chassis in the third direction in accordance with the third vibration suppression waveform; The vibration isolation device according to claim 3, further comprising the above.

5. The vibration isolation device according to claim 4, wherein the first direction, the second direction, and the third direction are substantially orthogonal to each other.

6. The vibration isolation device according to claim 1, wherein the controller is adapted to analyze a residual vibration component of the signal that exists while the second piezoelectric mass member applies the anti-vibration force, and to correct the first vibration suppression waveform to reduce the residual vibration component.

7. The vibration isolation device according to claim 1, wherein each of the piezoelectric mass members includes a piezoelectric crystal and a vibration mass.

8. A vibration isolation device for a module of a lithography system, the module having a chassis, the vibration isolation device comprising: a first sensor mechanically coupled to the chassis and arranged to detect a first direction component of a vibration waveform in a first direction and generate a first output indicative of the first direction component; a second sensor mechanically coupled to the chassis and arranged to detect a second direction component of a vibration waveform in a second direction different from the first direction and generate a second output indicative of the second direction component; a cancellation waveform generator arranged to receive the first output and the second output and generate a first vibration cancellation waveform for the first direction based at least in part on the first output and a second vibration cancellation waveform for the second direction based at least in part on the second output; a first actuator mechanically coupled to the chassis and arranged to receive the first vibration cancellation waveform and generate a first cancellation vibration corresponding to the first vibration cancellation waveform in the first direction; a second actuator mechanically coupled to the chassis and arranged to receive the second vibration cancellation waveform and generate a second cancellation vibration corresponding to the second vibration cancellation waveform in the second direction; comprising The anti-vibration system further is arranged to receive the first output and the second output, is adapted to identify a first residual vibration waveform for the first direction based at least in part on the first output while the first cancellation vibration is being generated and generate a first residual vibration suppression waveform based at least in part on the first residual vibration waveform and add the first residual vibration waveform to the first vibration cancellation waveform. configured to identify a second residual vibration waveform in the second direction based at least in part on the second output while the second cancellation vibration is being generated, generate a second residual vibration suppression waveform based at least in part on the second residual vibration waveform, and add the second residual vibration waveform to the second vibration cancellation waveform, a residual vibration cancellation waveform generator A vibration isolation device comprising: **Claim 9** The vibration isolation device according to claim 8, wherein the first sensor includes a first sensor piezoelectric transducer, and the second sensor includes a second sensor piezoelectric transducer. **Claim 10** The vibration isolation device according to claim 9, wherein each of the first sensor piezoelectric transducer and the second sensor piezoelectric transducer includes a piezoelectric crystal and a vibration mass. **Claim 11** The vibration isolation device according to claim 8, wherein the first actuator includes a first piezoelectric transducer, and the second actuator includes a second piezoelectric transducer. **Claim 12** The vibration isolation device according to claim 11, wherein each of the first piezoelectric transducer and the second piezoelectric transducer includes a piezoelectric crystal and a vibration mass. **Claim 13** The vibration isolation device according to claim 8, wherein the module includes a line narrowing module. **Claim 14** The vibration isolation device according to claim 8, wherein the residual vibration cancellation waveform generator is configured to identify the first residual vibration waveform by analyzing the wavelength of the first output with a wavelength sigma, and identify the second residual vibration waveform by analyzing the wavelength of the second output with the wavelength sigma. **Claim 15** The vibration isolation device according to claim 8, wherein the first direction is orthogonal to the second direction. **Claim 16** a third sensor mechanically coupled to the chassis and arranged to detect a third direction component of a vibration waveform in a third direction different from the first direction and the second direction and generate a third output indicative of the third direction component; the cancellation waveform generator arranged to receive the third output and generate a third vibration cancellation waveform for the third direction based at least in part on the third output; a third actuator mechanically coupled to the chassis and arranged to receive the third vibration cancellation waveform and generate a third cancellation vibration corresponding to the third vibration cancellation waveform in the third direction; arranged to receive said third output, while said third cancellation vibration is being generated, identifying a third residual vibration waveform for said third direction based at least in part on said third output and generating a third residual vibration suppression waveform based at least in part on said third residual vibration waveform and adapted to add said third residual vibration waveform to said third vibration cancellation waveform, said residual vibration cancellation waveform generator, The anti-vibration device according to claim 8, further comprising.

17. An anti-vibration method for a module for a lithography system, wherein said module has a chassis, and said anti-vibration method comprises: detecting a first direction component of a vibration waveform in a first direction and generating a first output indicative of said first direction component; detecting a second direction component of a vibration waveform in a second direction different from said first direction and generating a second output indicative of said second direction component; generating a first vibration cancellation waveform for said first direction based at least in part on said first output and generating a second vibration cancellation waveform for said second direction based at least in part on said second output; generating a first cancellation vibration in said first direction corresponding to said first vibration cancellation waveform; generating a second cancellation vibration in said second direction corresponding to said second vibration cancellation waveform; while said first cancellation vibration is being generated, identifying a first residual vibration waveform for said first direction based at least in part on said first output, generating a first residual vibration suppression waveform based at least in part on said first residual vibration waveform, and adding said first residual vibration waveform to said first vibration cancellation waveform; while said second cancellation vibration is being generated, identifying a second residual vibration waveform for said second direction based at least in part on said second output, generating a second residual vibration suppression waveform based at least in part on said second residual vibration waveform, and adding said second residual vibration waveform to said second vibration cancellation waveform; An anti-vibration method comprising.

18. Detecting the first-direction component of the vibration waveform in the first direction and generating the first output indicating the first-direction component is implemented using a first piezoelectric transducer, and detecting the second-direction component of the vibration waveform in the second direction and generating the second output indicating the second-direction component is implemented using a second piezoelectric transducer. The anti-vibration method according to claim 17.

19. Generating the first cancellation vibration in the first direction is implemented using a first piezoelectric transducer, and generating the second cancellation vibration in the second direction is implemented using a second piezoelectric transducer. The anti-vibration method according to claim 17.

20. Identifying the first residual vibration waveform includes analyzing the wavelength of the first output with a wavelength sigma, and identifying the second residual vibration waveform includes analyzing the wavelength of the second output with a wavelength sigma. The anti-vibration method according to claim 17.

21. The first direction is orthogonal to the second direction. The anti-vibration method according to claim 17.

22. Detecting a third-direction component of a vibration waveform in a third direction different from the first direction and the second direction and generating a third output indicating the third-direction component; Generating a third vibration cancellation waveform for the third direction at least partially based on the third output; Generating a third cancellation vibration corresponding to the third vibration cancellation waveform in the third direction; Identifying a third residual vibration waveform for the third direction at least partially based on the third output while the third cancellation vibration is being generated; Generating a third residual vibration suppression waveform at least partially based on the third residual vibration waveform and adding the third residual vibration waveform to the third vibration cancellation waveform; The anti-vibration method according to claim 17, further comprising.

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