TWI424645B - Method and apparatus for stabilizing and tuning the bandwidth of laser light - Google Patents

Description

Method and apparatus for stabilizing and tuning the bandwidth of a laser light Field of invention

The subject matter is directed to active control of bandwidth within, for example, a DUV gas discharge laser system (eg, an excimer or fluorine molecular laser system for, for example, a line narrowing application), for example, A laser source of one of the integrated circuits fabricated by photolithography.

Background of the invention

Stable bandwidth (eg, E ₉₅ for DUV semiconductor integrated circuit lithography laser source design) includes passive and active bandwidth control. Active control allows these sources to benefit from optical performance correction ("OPC") and tool-to-tool matching of such sources. US Provisional Patent Application Serial No. 60/923,486, entitled "TWO STAGE EXCIMER LASER WITH SYSTEM FOR BANDWIDTH CONTROL", filed on April 13, 2006, includes U.S. Patent Application Serial No. 11/510,037 ( The name is "ACTIVE SPECTRAL CONTROL OF DUV LIGHT SOURCE", filed on August 25, 2006, published on August 23, 2007, the disclosure of which is US-2007-0195836-A1, which claims Priority of US Provisional Application No. 60/774,770 (named "ACTIVE SPECTRAL CONTROL OF DUV LIGHT SOURCES FOR OPE MINIMIZATION", filed on February 17, 2006), the disclosure of each of these applications is incorporated by reference. The method is incorporated herein. The application of Serial No. 11/510,037 discloses a multi-stage bandwidth control system using coarse and fine control actuators.

The application discloses grating bending as an actuator (the position of a bandwidth control device "BCD" that bends the grating) and the use of other actuators. Various techniques for enabling bandwidth stabilization are discussed. Active bandwidth control systems can use very accurate on-board spectrum measurements (eg, E ₉₅ ) and bandwidth error feedback. Compensation based on other laser parameters/output signals (eg, target energy and duty cycle) can enable control of various bandwidth selection actuators, including low frequency large value actuators and a high frequency small amplitude actuation Device.

A lithographic source laser (a multiple input multiple output (MIMO) time varying nonlinear system) can use a (complex) actuator, except that the bandwidth is changed, the actuator itself may be thunder Shooting performance causes other effects (expected or undesired). Multi-step (e.g., dual-order actuator design), including the use of individual operational parameter inputs (actuators) to affect laser behavior, can be optimized to respond to a (plural) specific class of interference. Interference can be classified by time scale and/or size of influence. The pulse energy setting can include low amplitude fast time scale interference (typically milliseconds to seconds in a fine actuation range). The high duty cycle (in seconds) and the low (hour) frequency level of the duty cycle set point and fluorine gas consumption (in hours) may cause large amplitude effects. Other long-term parameter changes, component aging, and misalignment (day to week or even longer) can result in a change in maximum amplitude (in a coarse actuation range).

Thus, control actions classified into coarse actuation and fine actuation are disclosed, each using one or more parameter change actuators. One of them focuses on large-value low-frequency interference (large E ₉₅ set point changes, gas aging effects, and long time-scale elements of duty cycle changes)—for example, slow self-heating load changes, increased use time of laser components, and Similar to it). The other can focus on smaller amplitude higher frequency interference (output pulse energy and fast elements of duty cycle change - for example, from faster thermal load transients and the like). The coarse actuator can also be used to desaturate or reposition the center, with one (plural) fine actuator being within its control range.

A coarse actuator (for example, F ₂ gas injection) and a fine actuator (Δt _MOPA ) (grating bending or other front wave uniform adjustment or beam adjustment aperture, etc.) are displayed to adjust the bandwidth and together for bandwidth control, There are various effects on other laser parameters and the time frame of the measurement for feedback and actuation of the decoupling. The term dtMOPA or Δt _MOPA or differential emission time or differential discharge timing or differential calculation control (as used herein) is a simplified notation for the following concept: discharge between a source laser electrode and an amplifier laser electrode Timing to selectively amplify a portion of the source laser pulse within the amplifier gain medium to select the bandwidth of the output of the laser source. It is noted that a sufficient range of actuation is required to be able to address bandwidth deviations from such effects that are generally suppressed due to long term duty cycle variations, gas aging, and component aging. These controllers can be compensated/reduced for sensitivity due to error signal changes (filtering and other normalization) caused by other laser operating parameters.

Variable amplification of a beam incident on a central wavelength selective optical element (e.g., a dispersion grating) may also affect the bandwidth of the source. This system is discussed in U.S. Patent No. 6,393,037 (issued to Basting et al. on May 21, 2002), the content of which is hereby incorporated by reference. Basting's abstract describes a tunable laser comprising an angularly dispersive optical element (grating) and one or two included in a line narrowing module Rotate the beam expander to adjust the bandwidth. The complex 稜鏡 beam expanders (when both are used) are exposed to be mechanically connected to each other, so that when the magnification changes, the incident angle of the light beam on the dispersing element is not changed. This configuration makes it very difficult, if not impossible, to control the center wavelength and bandwidth with the rotation 稜鏡. In addition to this, it is very difficult for the bandwidth control system to use two twists of the serial operation.

It is believed that GigaPhoton has released a product that uses some kind of optical actuation to perform E ₉₅ control. Japanese Patent Application No. 2006024855 (issued on July 9, 2004) also discloses a variable-amplitude LNM with two rotating turns and a differential discharge between a source laser and an amplified laser. The transmission timing is used for bandwidth control. This configuration makes it difficult, if not impossible, to use the control center wavelength and bandwidth, and the use of dtMOPA to control the bandwidth within such a system may have some disadvantages.

Figure 12 (taken from the '037 application) describes the use of E ₉₅ bandwidth control center of △ t _MOPA. Using the differential transmit time as a fine actuator to control the E ₉₅ bandwidth has several advantages, including: (1) E ₉₅ measurements and Δt _MOPA changes can occur with approximately tens of pulse time stamps or shorter, such as pulses For pulses, allowing very high frequency interference rejection; and (2) the available range of actuation is large enough to attenuate/suppress the source of the target's bandwidth offset, ie the higher frequency of laser energy and duty cycle variation influences.

Existing types of active bandwidth control may have some drawbacks, such as recovering from a large amount of interference (eg, a transient after a fluorine injection) or a change in target bandwidth for too long. It may cause the bandwidth to leave the target as much as possible 5fm (when considering a 55-shot moving average) or 6 fm (when considering an example of a 55 standard deviation of firing, sum in points). It may take more than a few tens of seconds to return to the target.

In addition to this, especially at low duty cycles, a target change (for example, from 300 fm to 400) may be too slow, ie up to about 20 seconds, or from 400 fm to as low as 290 fm for up to about 30 seconds. When the requirement may be as low as about 10 seconds.

For other aspects, the error may be due to filtering of the control signal (eg, delaying too many pulses before a controller stepped signal can be sent to a bandwidth actuated stepper) so that the bandwidth can be sampled at a lower frequency On low duty cycles, there is a very high probability that stepping commands will not occur during a burst. Since the stepper command or the stepper itself can be enabled during a burst interval, bursts within the bandwidth can be established on each other and no correction signal is sent to the (complex) bandwidth. Control the actuator.

Conventional bandwidth stabilization control can set a bandwidth control set point in a set and forgotten manner. The more stringent requirements require a tunable bandwidth setting that can be controlled by the end user of the laser source. Bandwidth control systems are also required to have no negative impact on other laser operations or control of output parameters, such as output pulse energy and dose stabilization and the like.

The use of a variable aperture outside the laser cavity and active bandwidth control in conjunction with other bandwidth controlled actuators as proposed herein has advantages over prior art techniques. The optical components within the resonant cavity can be simplified and reduced in number, particularly in a single chamber or in an amplifier of a multi-variable laser system where the optical load is very severe. The variable aperture in combination with other actuators can be a coarse adjuster or a fine adjuster for bandwidth control.

Summary of invention

The present invention provides a method for controlling a bandwidth within a laser system, the laser system comprising: a gas discharge source laser having a resonant cavity and producing a source laser output; a gas discharge amplifier laser, Amplifying the source laser output and generating a laser system output; a bandwidth metric unit measuring a bandwidth of the laser system output and providing a bandwidth measurement value; and a bandwidth error signal generator receiving the bandwidth measurement value and a a bandwidth setting point and providing a bandwidth error signal; a variable amplification line narrowing unit, located in the resonant cavity of the source laser, comprising a grating and a variable beam amplifying optical system; a differential timing controller, Selecting a timing of a discharge between a pair of electrodes within the source laser and a pair of electrodes within the laser of the amplifier; the method comprising the steps of: controlling bandwidth using a bandwidth controller, the bandwidth control The device has three modes of amplification control, wherein a first mode does not control the amplification of the beam in the line narrowing unit, and a second mode narrows the line Of the beam to drive the amplified error signal independent of the bandwidth of a selected value, and a third mode according to the bandwidth of the amplified error signal drives the light within the narrow spectral line unit; and Wherein in each mode, the differential timing controller selects the timing based on the bandwidth error signal or does not consider the bandwidth error signal.

The invention provides a laser system comprising: a gas discharge seed source laser having a resonant cavity and generating a source laser output; a gas discharge amplifier laser, amplifying the source laser output and generating a laser system An output metric unit that measures a bandwidth of the output of the laser system and provides a bandwidth measurement value; and a bandwidth error signal generator that receives the bandwidth measurement value and a bandwidth set point and provides a bandwidth error signal; a magnifying line narrowing unit, located in the resonant cavity of the source laser, comprising a grating and a variable beam amplifying optical system; a differential timing controller for selecting a pair of electrodes in the source laser a timing of a discharge emission between a pair of electrodes within the laser of the amplifier; a bandwidth controller having three modes of amplification control, the bandwidth controller not controlling a first of the variable amplification line narrowing unit a mode, the bandwidth controller controlling the variable amplification line narrowing unit to drive the amplification to a second mode of a selected value independent of the bandwidth error signal, and the The wide controller controls the variable amplification line narrowing unit to select a third mode of the bandwidth of the laser system output according to the bandwidth error signal; and wherein the differential timing controller selects the timing according to the bandwidth error signal Or the bandwidth error signal is not considered.

The invention provides a laser system comprising: a laser light source comprising: a source laser defining an optical resonant cavity for generating an output; an amplifier laser receiving the laser output of the source and amplifying the source lightning a bandwidth measurement module that measures a bandwidth of a laser output light pulse pulse generated by the light source and generates a bandwidth measurement value; a bandwidth error signal generator receives the bandwidth measurement value and a bandwidth set point and A bandwidth error signal is provided; a bandwidth selecting component located outside the resonant cavity of the source laser, and a spatial portion of the beam is selected to selectively vary the bandwidth of the source laser output.

The present invention provides a laser system comprising: a source laser defining an optical resonant cavity that produces an output; an amplifier laser that receives and amplifies the output of the source laser and provides a laser system output; a bandwidth metric module for measuring a bandwidth of a laser output optical pulse beam generated by the light source and generating a bandwidth measurement value; a bandwidth error signal generator receiving the bandwidth measurement value and a bandwidth set point and providing a bandwidth error a differential timing system that echoes a bandwidth error signal to selectively adjust a differential transmission time between the source laser and the amplifier; and a beam adjustment system that is controllably adjusted The beam size of one of the beams in the resonant cavity of the source laser is selectively modified Varying the bandwidth of the source laser output and also controllably adjusting the center wavelength of the source pulse; and the beam size adjustment system includes: a plurality of beam size adjustments; and at least one other wavelength, including a center wavelength Choose 稜鏡.

The present invention provides an apparatus comprising: a source laser defining an optical resonant cavity that produces an output; an amplifier laser that receives and amplifies the output of the source laser and provides a laser system output; a bandwidth metric a module that measures a bandwidth of a laser output optical pulse beam pulse generated by the light source and generates a bandwidth measurement value; a bandwidth error signal generator receives the bandwidth measurement value and a bandwidth set point and provides a bandwidth error signal; a differential timing system that echoes a bandwidth error signal to selectively adjust a differential transmission time between the source laser and the amplifier; and a beam size adjustment system that controllably adjusts the source laser a beam size of a beam within the cavity to selectively vary the bandwidth of the source laser output and controllably adjust the center wavelength of the source pulse; and the beam size adjustment system includes: a plurality of beam size adjustments a dispersive optical element; and a center wavelength selective 稜鏡 at least partially defining an incident angle of the light beam on the dispersive optical element; A center wavelength selective mirror, in cooperation with the at least one other, defines the angle of incidence of the beam on the dispersive optical element.

Simple illustration

Figure 1 shows a bandwidth control device E ₉₅ sensitivity curve; Figure 2 depicts the interference type and time scale and amplitude of the layer according to one embodiment of the disclosed subject matter; Figure 3 is schematic and block The diagram shows a multi-stage gas discharge laser system with a variable amplification line narrowing module and differential emission time (dtMOPA) bandwidth control in accordance with one embodiment of the disclosed subject matter; Figure 4 Illustratively and in block diagram form an embodiment having four turns and a grating in accordance with a layer of one embodiment of the disclosed subject matter, wherein at least one turn can be rotated to increase/decrease the beam width, Thereby changing the bandwidth; Figure 5 depicts the overall architecture of a laser control system that can be used at the level of one of the disclosed embodiments; Figure 6 is a schematic and block diagram depicting one of the disclosed targets A representative laser system of the embodiment controls "implantation"; Figure 7 schematically and in block diagram form a bandwidth controller in accordance with one aspect of the disclosed embodiment; Figure 8 Schematic and block diagram The form describes a firing smoother in accordance with the level of one embodiment of the disclosed subject matter; FIG. 9 is a schematic and block diagram depicting a non-inductive hysteresis in accordance with the level of one embodiment of the disclosed subject matter. Figure 10 is a schematic and block diagram depicting a control mode selector in accordance with the level of one embodiment of the disclosed subject matter; Figure 11 is schematically and in block diagram depicting the disclosure according to the disclosure Example of a level having a plurality of Example Prism and a central wavelength selective mirror subject to one embodiment; FIG. 12 E ₉₅ describes the use of a bandwidth control center of △ t _MOPA; FIG. 13 schematically depicts the A variable amplification LNM in accordance with a level of one embodiment of the disclosed subject matter; FIG. 14 schematically and in block diagram form an adjustable aperture bandwidth control in accordance with a level of an embodiment of the disclosed subject matter Actuator (control center); Figure 15 shows schematically and in block diagram form a bandwidth control system in accordance with the level of one of the disclosed embodiments; and Figure 16 illustrates the aperture through which the beam passes. size Examples of changes in accordance with the bandwidth of.

Detailed description of the preferred embodiment

The primary purpose of active bandwidth control at the level of one of the disclosed embodiments is to control the E ₉₅ bandwidth of the laser, using the same or similar (complex) input signals as the previously used active bandwidth control system, but with different Signal processing and actuation mechanisms. Therefore, a tunable advanced bandwidth stabilization "ABS"("T-ABS") is proposed to control the bandwidth to a target set point that can be used by a laser end user or a laser light using a tool control system select.

Control bandwidth to ±50 fm or less (for constant pulse reception rate or other selected constant operating parameters) is proposed and is greater than 50 fm bandwidth With an error inside, the system is capable of returning to the set point with a firing rate greater than or equal to 0.0003 fm/ray. The center wavelength is not affected or minimally affected, while the bandwidth is controlled in a mode other than a target change mode (through <5 fm - consider a 55 shot moving average wavelength value - and <6 fm - consider a 55 For example, the firing standard deviation is summed by the integral). A control algorithm can use various bandwidth actuators to control the stepper for bandwidth selection (thick and thin), including a variable amplification line narrowing module ("VMLNM"), a bandwidth control module ( "BWCM"), a beam analysis module ("BAM"), as discussed herein.

A measured E ₉₅ signal is used to determine the adjustment of a Bandwidth Control Device ("BCD") or the like. BCDs that include mechanisms for deforming the central wavelength selective grating to affect the bandwidth of the output of the laser source are well known in the art. Bandwidth control can be achieved by maintaining a particular side of a BCD operating curve, such as to the right or left of the BCD curve, as depicted in Figure 1.

Applicants have noted that the interference 80 can be classified by the time scale and/or amplitude affecting these laser operating parameters (e.g., E ₉₅ bandwidth), as depicted in the graph of Figure 2, and if the serial number is 11 US Patent Application No. 5,510,037, entitled "ACTIVE SPECTRAL CONTROL OF DUV LIGHT SOURCE", filed on August 25, 2006, issued on August 23, 2007, publication number US-2007-0195836-A1 As explained in greater detail, this application is incorporated herein by reference. As explained herein, a fine actuation range 82 (eg, energy change or higher frequency duty cycle effect) or coarse actuation range 84 (eg, lower frequency duty cycle effects, gas aging or component aging/misalignment) Such interferences 80 within can be generated by a bandwidth controlled actuator (coarse actuation or fine actuation or both).

Figure 3 shows a multi-stage gas discharge laser 500 with a variable amplification line narrowing module and differential emission time (dtMOPA) bandwidth control. The first stage may be a main oscillator MO, and the next stage may be a single channel power amplifier, a multi-channel power amplifier, a power oscillator or a row-wave amplifier (for example, a power loop amplifier), wherein the oscillation is as a Occurs in the cavity of the amplification stage.

An example of such a laser system may include some or all of the elements shown in Figure 3, depending on the configuration. The component shown in FIG. 3 includes a variable amplification line narrowing module 502, a first stage chamber 504, a first stage output coupler 506, steering optical elements 508a, b, and an input coupling. The device 510, a second stage chamber 512, a beam splitter 514, a bandwidth measuring module 516 and a discharge timing control module 518. The source laser 504 can be a gas discharge excimer or a fluorine molecular laser, such as an XCl, XF, KrF, ArF, F2 or similar laser. These types of lasers are known for lithography process processing of wafers to fabricate semiconductor circuits. The source laser 504 can define, for example, an optical resonant cavity between the line narrowing module 502 and the output coupler 506 and produce an output. The amplifier laser 512 can receive a source laser output through the relay optics (mirrors 508a and b) and amplify the source laser output to produce a laser system output. The bandwidth metric module 516 (known in the art) can measure the bandwidth of a laser output and can provide a bandwidth measurement that can be used by a bandwidth controller 518 (as discussed below). 518 can be individual units to produce a comparable to a target/set point Bandwidth error. The differential timing can be adjusted based on the error signal to adjust the laser system output bandwidth.

Figure 4 shows one possible embodiment of a bandwidth (and center wavelength) actuator mechanism (control center) having four turns 520, 522, 524, 526 and a grating 528. The crucible 520 can be fixed to an actuator (not shown) including a rotationally fixed (eg, a curved fixation (not shown)) such that the crucible 520 can be transmitted through a rotary actuator (eg, A stepper motor (not shown) and/or PZT (not shown) rotates to increase/decrease the beam width, thereby changing the bandwidth. The crucible 522 can remain stationary or can have a rotational position actuator (not shown). The crucible 524 is also fixed for rotational movement (as described for 520) (for example) to fine tune the center wavelength (eg, in the order of femto ( ^10-15 m)). The crucible 524 can also be fixed in such a way as to coarsely adjust the center wavelength (e.g., on a scale of 10 x 10 ^-15 m).

Figure 11 schematically depicts one possible embodiment of a bandwidth (and center wavelength) actuator (control center), wherein the R _MAX mirror 540 and its actuator 540a (which is the center of the laser system) As is well known in the art of wavelength selection, it can be used to refract the extended beam from the beam extension 526 back to a grating 528. The grating 528 can be an elongated grating to use an expanded beam, such as a beam that is extended by 45X. By determining the angle of incidence of the beam on the grating 528, the mirror 540 can be used in part for center wavelength control. The R _MAX folding mirrors known in the art can have coarse and fine center wavelength control for a single optical component, ie, a stepper motor (not shown) for coarse control and a PZT stack (Fig. Not shown) for fine and fast center wavelength control, as noted above. When combined with a central wavelength control 稜鏡 (e.g., 稜鏡 520), the R _MAX mirror 540 can maintain its control relative to the angle of the grating 528 or use only fine control of the PZT stack without using any stepper motor control. The center wavelength control 稜鏡 (eg, 稜鏡 520) can be used for coarse control, and then the R _MAX folding mirror 540 can be used for finer center wavelength control, or vice versa.

In the latter embodiment, the PZT stack can be deleted, and only one stepper motor is used to position the _RMAX folding mirror for coarse center wavelength control, while the center wavelength control can be used for comparison. Fine center wavelength selection. Alternatively, each of the series of turns provided in the beam expansion mechanism may have a rough control and fine control similar to R _MAX , wherein a stepper motor is used for coarse adjustment and for a PZT stack. For fine adjustment, or the coarse adjustment can be controlled using a stepper motor or similar mechanical adjustment, and the fine adjustment is controlled by a faster and thinner control actuator (eg A PZT stack).

The signal can be received from the laser hardware to indicate a measurement from the E ₉₅ bandwidth of the most recent laser light. A controller (as shown in FIG. 7) or portions of components 502 and/or 518 can then process the signals through various filtering, deadbands, hysteresis, and smoothing and generate a (plural) command. One (plural) output of the form is one of the functions (plural) actuators that perform such functions as, for example, moving or distorting a (plural) mechanical and/or optical component. This movement or distortion (and other) components can cause a change of the bandwidth of the E ₉₅ to reduce the bandwidth errors.

There may be several control modes, such as the following but not limited to the following, in which no amplification control is implemented (i.e., the variable amplification LNM variation system is not used), and thus there is no effect on bandwidth control due to variable amplification. In this mode, there can be two sub-modes, in one mode, the dtMOPA laser timing is not used to directly control the bandwidth, and in one mode, dtMOPA is used to directly control the bandwidth.

In a second amplified drive mode, variable amplification is also unused, although the system drives the variable amplification to a selected value (e.g., to a maximum value, e.g., to 45X). In this second variable amplification mode, for a first dtMOPA timing mode, the energy and timing control algorithm sets dtMOPA, and dtMOPA or variable amplification (except for being driven to a selected value, such as full 45X amplification) Not changed for bandwidth control. For a second dtMOPA timing control mode, the bandwidth is set using dtMOPA while the amplification is maintained at, for example, 45X amplification.

Another amplification control mode can be used, where amplification is based on some bandwidth feedback control bandwidth. The magnification can then be selected based on one of the bandwidth targets, as noted above. In this mode of amplification control of a first dtMOPA control mode, the energy and timing control algorithm sets dtMOPA timing for reasons other than bandwidth control, such as laser efficiency, dose stabilization, or the like. The magnification is selected to obtain a selected bandwidth that is independent of dtMOPA. In a second dtMOPA control mode, both the magnification of the VMLNM and the dtMOPA can be selected to achieve a target bandwidth, one of which is used as a coarse bandwidth selection mechanism and the other as a fine selection mechanism.

The system can be set such that a deadband with a hysteresis configuration is used, such that, for example, control only initiates when the error (absolute value) leaves a large/outer sense zone and returns to the error Closed when the smaller/inner is not sensed. Moreover, bandwidth motor jitter can be used, for example, The limit value, the lower limit of the number of microsteps in one direction before changing direction. In addition to utilizing a bandwidth target change, the system can be configured to obtain a time limit value for a given duty cycle (eg, for example, 100 burst lengths, 5% DC for 10 seconds) The new target within, while the use of lithographic light sources is disabled. This can limit jitter and/or custom bandwidth control to specify customer requirements.

When the filtered bandwidth is out of band, the controller can command the stepper in only one direction to prevent operational-related jitter near the band boundary. If the bandwidth (error signal) is greater than the high/outer sense band value, then the control enables the bandwidth control actuator feedback position/initialization command to be issued, and if the bandwidth (error signal) is less than the low/inner sense band value, the disable command is issued. issue. Otherwise, the system does not change the current command issue state (enabled or disabled), and the bandwidth (error signal) is intermediate between the high/outer sensed value and the low/inner sensed value. In other words, when the bandwidth (error) signal is in the middle of the non-inductive band limit value (has entered the region from a high value), so that the input command is issued, so that it remains enabled until the bandwidth (error) signal After the low/inner is not sensed, the command is issued and disabled. Similarly, when the value from less than the low/inner sense band (where the command is issued is disabled), this function remains disabled until the bandwidth (error) signal passes the high/outer sense band value.

The size of the insensitive band can be chosen to choose between several performance values, such as reduced jitter, controller response time versus total speed of interference, and the amount of bandwidth error allowed.

The system can use a function generator (a rich set of features can be used) to (by way of example only) command a bandwidth controlled actuator (eg, a stepper motor) to Any function that fires a number.

Individual hardware and software "gains" can be used for software (to promote hardware renewal capabilities).

A controller holdoff can also be used, such that, for example, at the beginning of a burst, no bandwidth steps are allowed within some pulses, such as within 30 firings after the start of a burst.

The three basic operations of the bandwidth control system can be performed using a bandwidth actuator (e.g., a variable amplification LNM). The firing process can occur on each shot (one shot is indicated by the LAM update). Bandwidth target change processing can occur when a bandwidth target change occurs.

The firing process logic can be executed whenever the line center (wavelength) analysis module ("LAM") returns the wavelength data (eg, based on a firing-by-shot basis). With a shot data record, the input signal can be checked. The algorithm can perform its calculations and move the results into the same firing data record. A Bandwidth Analysis Module ("BAM") status signal can be used to determine if new bandwidth data (eg, E ₉₅ bandwidth data) is available. The system can then attempt to filter out bad or other invalid bandwidth data.

The bandwidth control system (eg, using a bandwidth control actuator (eg, a variable amplification line narrowing module ("VMLNM") bandwidth control system) may be required to: (1) stabilize the bandwidth at some Within the selected bandwidth, for example, approximately ±50 fm; (2) correcting the error of the bandwidth from a selected target or set point at a selected rate (eg, approximately 0.0003 fm/shot); (3) ensuring that wavelength stability is maintained, For example, when using bandwidth control with a bandwidth actuator allows no more than a selected value (eg, about 5 fm extra 55-fired moving average wavelength error) Poor), and no more than a selected value (for example, an additional 55-spin shift standard deviation at a wavelength error of about 6 fm); (4) including a non-inductive band with hysteresis that can be used to change performance; (5) To prevent the stepper motor from shaking, the stepper must therefore be stepped through at least a selected number in one direction (eg, approximately 16 steps) before stepping in the other direction; and (6) provided for The change in bandwidth target can be achieved in a selected time, such as, for example, one of 200 pulses per second with a minimum firing rate of about 10 seconds (for a 4 kHz pulse repetition rate laser system).

Therefore, a filter can be used only when the bandwidth is updated. Between bandwidth updates, other functions can occur (eg, step smoothing), but most other functions depend on the error being filtered. Therefore, if and if this does not change, the other controller states remain constant. The system can also use the bandwidth control algorithm determined using the MOPA timing mode and the BW stepper mode and can also use a BW stepper motor function generator/play and provide a "reset" of the BW stepper to baseline amplification. .

The bandwidth target may be required to change at a selected time, such as approximately 10 seconds. Wavelength stability may not be required within specifications during bandwidth target changes. A target change indicates that the stepper may need to move at its fastest rate. The algorithm can command the stepper to move in the correct direction at the fastest possible rate and stop the stepper when the measured bandwidth approaches the target. Alternatively, the algorithm can use the knowledge of the bandwidth versus step curve and the position sensing of the absolute step to estimate the correct number of steps used to obtain the target bandwidth.

If the number of firings in the current burst is less than or equal to one is stored Value (representing the number of firings used to prevent bandwidth stepping at the beginning of a burst) and if the state of the target change pattern is enabled ("1"), the system can control the step used for this shot based on feedback control The number of steps is set to =0. Based on the feedback control, the total number of bandwidth steps used for this firing can be calculated as the number of microsteps used to command a bandwidth control mechanism to actuate the stepper (eg, a variable amplification 稜鏡 rotary stepper) equal to being The number of steps in the command.

The algorithm output can be updated, for example, if the absolute value of the number of microsteps used to command the control actuator (eg, the variable amplification stepper) is greater than zero or if the current target change state is prior to the previous The algorithm output can be set to 1 if the target change state is different, otherwise it is set to 0. The algorithm output may be a signal indicating whether a new stepper command needs to be sent to the controller to actuate the bandwidth change to reduce the error signal (eg, whether a BWCM is enabled, as discussed below). A signal of the stepper is actuated by updating a bandwidth control mechanism. The stepper can be a variable amplification LNM rotation 稜鏡.

When a target change is detected, the algorithm can determine a new tracking error based on the currently filtered error, the previous bandwidth target, and the new bandwidth target, ie, the filtered error plus the previous target minus the new one. The goal. This provides the correct direction for the stepper to move. The algorithm can then also reset the filter such that the filtered error is equal to the new tracking error. The system can command the stepper to move at a maximum rate in the desired direction (referred to as "slewing" until the filtered bandwidth error is in a selected one that is capable of stopping the spin and without overshooting Within the scope. The algorithm can also check if the filtered error changes the sign during the spin. Once this If any of the conditions are not met, the controller can return to normal control.

Bandwidth "spikes" may occur due to large wavelength changes. During a bandwidth target change cyclotron, the wavelength may also be affected due to the coupling of the bandwidth step to the wavelength. Although the wavelength controller can compensate for such variations, it cannot do so during the inter-band interval, such that if the stepper continues to gyrate, the wavelength may change. After the inter-band interval, the wavelength controller may have to respond to a new and relatively large wavelength error. This can result in a fast and large change in one of the wavelengths, even with the ability to change substantially at 2 pm, a very fast (and fine) wavelength control mechanism (eg, based on a _RMAX PZT stack) or changing the grating The 稜鏡 positioning element of the incident angle of the beam (as a dominant wavelength control source).

The change in wavelength during a BAM integration can be perceived by BAM as an increase in bandwidth. In general, the faster the wavelength changes, the greater the positive deviation within the BAM measurement. If the wavelength changes quickly enough, in some cases an unusually large "spike" can be reported by BAM. During a target change, such spikes may cause the controller to misinterpret the spike as indicating that the bandwidth swing has completed and returning to normal control very early before reaching the target. This may cause the target change to take much longer than the selected time, for example, greater than 10 seconds.

The controller can implement several methods to filter out such bandwidth spikes. This spike may be caused by a large wavelength change over a short period of time. The bandwidth measurement is ignored as a filter when the wavelength changes more than a certain amount during a BAM integration window, and the filter ignores a bandwidth measurement when the total included wavelength range is greater than a predetermined value. The actual limit value of the actual bandwidth (add noise) is enabled to filter, thereby ignoring any bandwidth readings greater than a predetermined value (eg For example, 2x maximum bandwidth). When a bandwidth reading is filtered/ignored, the last good (ie, not ignored) measurement can be used at its location. Typical values may be the maximum allowed wavelength TIR = 300 fm and the maximum allowed bandwidth to be reported = 1000 fm.

The first few shots of a burst can generally be characterized by large and sometimes repeatable transients within wavelength and energy. The wavelength control algorithm can include logic that can prevent transient overreaction of the bursts. However, the wavelength is more sensitive to interference during this initialization. The bandwidth stepping (which may cause a wavelength change) may be prevented by a burst of the first selected number of firings, referred to in this application as a burst delay. The number of delayed firings is a controller operating parameter and can be approximately 3 firings.

In accordance with another possible embodiment (as schematically depicted in Figure 13), an LNM having four 稜鏡520, 522, 524, and 526 for controlling bandwidth and wavelength is displayed. Both of these 524 and 526 can be rotated by an actuator (not shown) similar to the actuators of 稜鏡524, 526 shown in Figures 4 and 5. One turn 526 can be rotated by a stepper motor actuator (not shown) and the other turn 524 can be rotated by a PZT stack (not shown). The two turns 526 and 524 can be used for coarse and fine adjustment of the wavelength, respectively. They are positioned to respond to signals from a central wavelength controller system that the center wavelength is not at the target due to target changes or center wavelength drift. At least one of the other ports can be rotated for bandwidth control, such as 稜鏡 520. Rotation can be achieved using a stepper motor (not shown).

Figure 5 depicts, in block diagram form, an overall architecture of a laser system controller 200 including bandwidth and wavelength control, generally with the serial number 6690704 The controllers discussed in the U.S. Patent (which is incorporated herein by reference) are the same, and a bandwidth control module ("BWCM") 220 and a variable amplification line narrowing module ("VMLNM") 222 are attached. . A launch control platform ("FCP") processor 202 can control, for example, the emission of discharges between electrodes within a single chamber laser system (eg, Cymer's 7000 Series laser system) or a source laser amplifier Emission of discharge between electrodes in each of a plurality of laser chambers (e.g., the MOPA laser system of the XLA series of Cymer or the MOPO laser system of the XLR series). The FCP 202 can use control algorithm software and provide control signals to a transmit control communicator ("FCC") 204.

The FCP 202 can respond to command signals from a laser control processor ("LCP") 206 and communicate with the LCP 206. The FCC 204 is available from a Beam Analysis Module ("BAM") 210 (some similar to the Spectrum Analysis Module ("SAM") (for bandwidth) and a Line Center Analysis Module ("LAM" discussed in the '704 patent) 212) (for center wavelength) receives wavelength and bandwidth information, and may interrupt the FCP 202 to perform a wavelength or bandwidth control algorithm or both. The FCC 204 may also pass the FCP 202 command to a bandwidth control mode. Group ("BWCM") 220, which can be used to command all actuators used to control bandwidth or wavelength, such as may exist within a variable amplification line narrowing module ("VMLNM") 222. The state of the VMLNM 222 and its actuators can be communicated back to the FCP 202 via the FCC 204.

Figure 6 depicts a representative laser system "implantation model" in block diagram form in which a bandwidth (or possibly wavelength) stepper motor step command 232 can be input to an adder 234 and One output of this delay 236 The summation provides an input to a step-by-step BW lookup that produces a desired bandwidth value for the BW lookup, the desired bandwidth value being input to an adder 242 and a representative interference request from the interference block 240. with. After the same delay block 244, the output of the adder 242 sums up a constant from the constant block 248 and the noise from the noise block 247 in the adder 246 to produce the measured bandwidth on the output 249. One said.

Figure 7 shows an illustrative example of a bandwidth controller 250. The controller 250 can have a bandwidth (or possibly wavelength) target 252, a measured bandwidth (wavelength) 254, and an input of wavelength TIR 256, the latter two of which are input to a "bad" bandwidth measurement processor. 257, one of its "good" bandwidth outputs is summed with the target bandwidth input 252 in an adder 258 to provide an input to a noise filter 260. If the bandwidth measurement needs to be filtered/ignored (eg, because the measurement or TIR is too large), the output of block 257 will be a previously measured "good" bandwidth, otherwise the measured bandwidth may be Pass block 257.

The output of the noise filter 260 provides an input to the one-step command path, a mode selection path, and a whirling step path. The step command path may include a non-inductive strip having a hysteresis "on/off" block 262, an example of which is described in more detail in FIG. If the non-inductive output with hysteresis is fed back to the enable enable/start mode (eg, a 1), the output of the multiplier 270 is the output of the noise filter 260 and if it is actuated by feedback When disable/off mode 0, the output of the multiplier 270 is zero. The output of the multiplier 270 is amplified by a gain factor K in the control gain amplifier 272 and passed through a command saturation block 274 to the step-by-step smoother 276, an example of which is shown in detail in FIG. . The command saturation block can be used to limit The effect of the bandwidth step rate on the center wavelength control. A limit value can be established equal to the maximum step of each picture (eg, each time the BAM/bandwidth measurement updates 0.1 times the shot (nominally 30), in this case it will be 3 steps).

The mode selection path may include a control mode selector 264, an example of which is shown in detail in FIG. The mode selector 264 receives the output of the noise filter 260 (on a BW error input) and the output of a target change detector 268 is an input having a bandwidth target from the input 252. One of the inputs. The output of the target change detector 268 forms an input to the target change input of the mode selector 264. The whirling step path can include a sign block 266 that receives the output of the noise filter 260, the output of the sign block 266 being amplified by a factor N within a target change whirling stepper amplifier 278.

The output of each of the paths provides input to an individual terminal of a three-pole switch 280, the output of which is a one-step command 284.

Figure 9 depicts, in block diagram form, a non-inductive hysteresis control block 262 that can take the output of the noise filter 260 as an input 290, as depicted in Figure 7. The input 290 can be provided to an absolute value function block 292, the output of which can be provided to a relay block 294, which can include (as an example) a symmetry with hysteresis The switch provides an "on/off" output 296. The symmetrical switch 294 can act to generate an "on" output when the bandwidth error (or possibly the non-inductively measured bandwidth within the bandwidth itself, as opposed to the bandwidth error) is greater than the outer/high non-inductive value ("1 "), and when it is less than the inner/low bandwidth value, a "cutoff" ("0") is generated. Absolute use of error signals when compared to a high or low sense When using values, using bandwidth errors is only logically easy to implement. If the previous output is a "1" / "on", the switch 294 can generate an "on" output when the bandwidth error is between the high/outer sensed value and the low/inner sensed value, and The reverse is also true when the previous output is "0" / "off". This is the meaning of hysteresis in this article.

As described in FIG. 8, the step-by-step smoother 276 can take a one-step command as an input, such as a step command from the command saturation block 274 illustrated in FIG. The step smoother 276 can include a divider that divides the input step command c of the advanced step by the number (or time) T of shots used to advance the c number of steps. The output of the divider 340 provides an input to an adder 342 and a block 360.

The output of the adder 342 is provided to a multiplier block 346 whose output X step is rounded to the nearest integer within the rounding block 350. The output of block 350 forms an output command of one of the steps of s, which is provided to switch 280 as described in FIG. The output of the multiplier block 346 is also subtracted from the output of the rounding block 350 in an adder 348 to provide an input to the same local delay 344, the output of which provides an input to the adder 342. There is a need to ensure that there is a limit on the bandwidth control actuator step to limit the effects of wavelength control (eg, wavelength lock), which may be every 10 shots 1 BW step to maintain WL lock (which should not be an average). The BW control loop is executed every 30 firings (corresponding to the BAM update rate), and if the control loop is expected to have a maximum of 3 steps during the 30 firings, this will average to only 1 step. /10 shots. However, if the BWCM commands all three at a time, other system requirements may be disturbed. There is a need to evenly distribute the steps during 30 firings, which is performed by the step smoother 276.

The input (command c step) is also provided to an adder 364 within the adder 364 and one of the output of the rounding block 350 and the delayed output in block 368 in adder 370. The result of the single sample delay sum is summed, wherein the output of the adder 364 provides an input to a single sample delay block 366. After the same delay in block 366, the output of block 364 provides an input to an absolute block 354. The output of block 354 is compared in block 352 to check if it is greater than a value "r" derived from the truncation block 360, wherein the result of the division in block 340 is removed by removing any decimal of the result. The portion is truncated and summed with a constant (e.g., 1.0) in adder 358 and multiplied by a value (e.g., 0.5) within multiplier block 356 to provide an input r to comparator block 352. The elements of the step smoother 256 outside the dashed line ensure that the step stops after the number of steps required to be commanded (i.e., c). Otherwise, if there is no BAM update for a BAM update next time, the stepper may only keep stepping the bandwidth control mechanism even if a no-in/down limit value is passed.

The controller 250 can have several parameters, the values of which can be selected and the representative values are noted in parentheses, for example, the noise filter coefficient C (0.9735), the controller gain K(1), and the in-band sense. And external limit values ((1.0 fm) and do (9.5 fm), respectively), command saturation limit value L (2 steps per BAM update period), target-change-complete error limit value M (15 fm), The maximum allowed wavelength TIR (300-400 fm) and the maximum allowed bandwidth (600-1000 fm).

Given these factors (such as sensor noise, performance requirements, and robustness), these parameters can be combined in a highly nonlinear manner when determining the overall performance within a closed loop. Therefore, the applicant has decided to choose a parameter that starts to be loosely coupled. The maximum allowed TIR is selected based on an experiment during a target change maneuver, which is considered to be a worst case continuous operation. For an exemplary ArF laser system, in normal operating conditions, the maximum possible bandwidth is approximately 300-500 fm, so the number 2 gives the selected limit value.

In the case of an ArF laser system, M is selected because the one-filter test signal may have a large delay between the actual signal and the test signal, resulting in early stopping of a target change cyclotron to prevent excessive overshoot. For L, because the bandwidth and wavelength stepper may affect the bandwidth, the wavelength stepper can be moved to compensate for a bandwidth stepper movement (a control center bandwidth control actuation), such as through the PZT in the wavelength controller. saturation. The change in wavelength due to the bandwidth step can be offset by the wavelength step. For K (with wavelength stepper rate limit), the controller has a virtually unlimited gain margin. The control gain is selected so the command is always always saturated, providing the fastest response time. When the bandwidth stepper provides ~0.005 fm per step (2 steps per 30 shots), each shot has 0.00033 fm to meet other system requirements. For d _o = 9.5, the tuning does not sense the limit value d _i , (for example, for customer bandwidth control requirements) and the value filtered by the re-filtering representation is the actual instantaneous bandwidth (except in the bandwidth (eg, step) Under rapid changes), d _o can be provided for the nominal bandwidth of the actual bandwidth. Bandwidth measurement noise is similar to white Gaussian (standard deviation ~20 fm, one of the total bandwidth is less than (2*9.5=19 fm)) is reasonable to limit the actuation of the stepper. The internal insufficiency limit value d _i = 1.0 maximizes the non-inductive hysteresis, minimizing the jitter of a control center within a command of a bandwidth controlled actuation stepper or other actuator. Moreover, when the bandwidth is measured at a resolution of about 1 fm, it is ineffective if the inner non-inductive band is set less than 1 fm. For C, increased stability and blocking of noise filter jitter may also increase latency, an excessive amount of which is undesirable. Command saturation can be selected from the ratio of wavelength variation to wavelength and bandwidth controller actuation steps, and it is desirable to compensate a bandwidth actuation step with a single wavelength step and round to integer steps because if rounded, then The wavelength stepper may make the bandwidth step backwards. For a 30-shot BAM integration period, the wavelength controller can allow 1 wavelength step to be fired every 30 shots. Therefore L = 2 (which is approximately 0.00033 per shot) meets the system requirements. If the size of the steps needs to be increased (or their effect on bandwidth), this may reduce the gain margin.

The step response of the noise filter can be: y _k =u(1-c ^k )+y ₀ +v _k

Where u is the size of the step input, y ₀ is the initial output, C is the coefficient, v is the filtered noise and k = 30 * (the number of shots). When stepping controller 250 does not interfere with the sense, control action may not start until the filtered error d _o increase above, the time which is required for an initial delay produced by the filter. When y is crossed, the solution is k:

Among them, C<1 is known. Suppose that before the actual filtered bandwidth reaches the insensitive band (due to noise and ignores the "spike" of the noise), the non-inductive (average) is 1 sigma, where d _o >y ₀ and avoid u+y ₀ <d _o (indicating u+y ₀ -d _o >0), when u is large and u+y ₀ -d _o , k can be maximized. Even so, there may be a combination of interference and one of the initial conditions such that the filtered error passes through d _o for almost infinite time, independent of C. When using the bandwidth measured by 1 fm resolution (the minimum value of u + y ₀ -d _o is reasonable) and using d _o = 9.5 (the maximum value of u that minimizes u + y ₀ -d _o =1 is u = 2*d _o +1=20), an initial condition can be set at the "bottom" of the insensitive band, and a stepping disturbance is sufficient to leave the "top" of the insensitive band. The first-order filter response (no overshoot) may take the longest time to exit the insensitive band. With a minimum firing rate of 30 shots per sample and a minimum firing rate of 200 shots per second, the maximum time to leave the strip is determined by:

Where σ _s is the sensor noise standard deviation, for example, equal to 20 fm. This defines an absolute worst case, and a Monte Carlo study shows that the typical delay is less than 0.5 seconds, resulting in a 10 second delay (a reasonable choice) such that a filter coefficient of C = 0.9735 is reasonable.

A stepper motor in combination with one of the BWCMs can be used as an accumulator (integrator) with a rate limit value (4000 microsteps per second), which can also be completely noise free. BW is a non-linear function of absolute stepper position and may also have negligible coupling from WL to BW, which may allow the BW control loop to be individually turned off and independent of other loops. However, coupling from BW to WL and deriving WL error One of the 5 fm requirements may require special consideration. Although the controlled implant can be used as a natural integrator (with good noise rejection characteristics), additional filtering may be required to help prevent jitter within the stepper commands.

The system may seek to move the bandwidth control mechanism stepper to a baseline position, such as a baseline amplification or a baseline aperture or the like. This can be performed by using a limit switch (eg, within the LNM), issuing a large number of steps (for example) to maximize amplification and waiting for an interrupt signal from a different limit switch, which causes the BWCM to come from the limit The signal of the switch stops the command stepper actuation. The same can be applied to other bandwidth controlled actuators, such as an adjustable aperture. The limit switch position should be set to a known bandwidth setting, such as a known amplification or a known aperture size and position. When this function is implemented, a BW versus step curve can also be measured and updated.

The Applicant has simulated this bandwidth control system and since this simulation decision, the system response can be dominated by the algorithm BW stepper rate limit value (eg, ~0.0005 fm/shot). Filtering can effectively improve the noise response to reduce the band. The controller gain can be set high enough so the stepper command is always saturated or "off". The system can achieve error = (without internal sensing) + (~3σ filtered noise), the error is low when the noise spike triggers the accidental step (assuming no interference). This dive can be minimized by increasing the magnitude of the hysteresis. The non-inductive noise filter can effectively eliminate jitter. The system can be highly robust with a virtually unlimited gain margin. The BW stepper rate limit value and no sense band prevent noise from injecting the system into the system.

A center wavelength selection mechanism can include a dispersive optical element, and the center wavelength selection chirp and/or other center wavelength selective optics are controllably The angle of incidence of the beam on the dispersive optical element is adjusted. The differential timing system can include a coarse bandwidth control adjustment, or vice versa. Various combinations of coarse and thin bandwidth and/or center wavelength control actuation can be used.

According to another possible embodiment (schematically depicted in Figure 13), an LNM having four 稜鏡520, 522, 524, 526 for controlling bandwidth and wavelength is displayed. Two of the ports 524 and 526 can be rotated by actuators (not shown) similar to the actuators of the ports 524, 526 of Figures 4 and 11. One turn 526 can be rotated by a stepper motor actuator (not shown) and the other turn 524 can be rotated by a PZT stack (not shown). The two turns 526 and 524 can be used for coarse adjustment and fine adjustment of the wavelength, respectively. They are positioned to respond to signals from a central wavelength controller system that the center wavelength is not at the target due to target changes or center wavelength drift. At least one of the other ports can be rotated for bandwidth control, such as 稜鏡 520. Rotation can be achieved with a stepper motor (not shown).

A method can be used to control the spectral profile (bandwidth) of a source laser amplifier laser configuration (eg, a MOPA or MOPO laser system), which may be more suitable for a MOPO laser because it reduces input to The MO energy of the second (amplifier) stage 512. This method may not rely on dtMOPA timing control, its use may have an undesirable negative effect on one or more other laser system operating parameters (eg, energy stability), although dtMOPA timing control can be used to expand here. The device and method described. The apparatus and method can be used to provide symmetry and asymmetry control of a laser control spectrum.

Use a 稜鏡 and / or folding mirror and narrow based on the grating spectrum The output spectrum of the laser of the method may have a spatial non-uniformity of wavelengths, for example, in a direction perpendicular to the sawtooth structure of the grating. Figure 16 depicts an example of a change in bandwidth that depends on the size of the aperture through which the beam passes. By, for example, an adjustable aperture (e.g., 158 in Fig. 14 or 610 in Fig. 15, or as shown in the co-pending patent application Serial No. 11/173,988, the The patent name is "ACTIVE BANDWIDTH CONTROL FOR A TUNED LASER", filed on June 30, 2005, which is incorporated herein by reference in its entirety, in its entirety, in its entirety, the entire entire A portion of the beam is injected into the power amplifier or power oscillator (e.g., amplifier 512, which is schematically depicted in FIG. 3), and the system output spectral bandwidth can be controlled. A power amplifier or power oscillator used as a second stage (amplifier) (eg, 512 in Figure 3) may require some input beam size, which may be by two lenses or similar devices (eg, a beam expander)稜鏡 稜鏡 ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) The purpose of bandwidth. As an example, an adjustable beam expanding collimator 600, schematically depicted in Fig. 15, can be used.

A bandwidth monitor (e.g., within a Band Analysis Module ("BAM") 516 in Figure 3) can provide a feedback signal to a bandwidth controller (e.g., 620 in Figure 15), the bandwidth control The bandwidth signal can be used to adjust a portion of the beam passing through the adjustable aperture 610, for example, in which case the beam selection aperture size and beam shaping are controlled to select a bandwidth and beam size for the amplification stage of the laser system to provide Symmetry and non-symmetry of spectrum shape (bandwidth) Symmetrical control, which can be performed, for example, within the adjustable beam expander/collimator 600. It will be appreciated that the bandwidth of the source laser beam (e.g., MO beam) prior to the adjustable aperture should be large enough to provide a desired range of spectral bandwidth after the aperture is adjustable.

If desired, in accordance with the subject matter of this disclosure, for the benefit of laser operating parameters other than bandwidth (eg, pulse energy, dose stability, and the like), the dtMOPA timing can be used independently to allow the MOPA laser to be the most Good dtMOPA timing operation, while the adjustable aperture 610 or other form of active bandwidth control can be used in conjunction with one or more other bandwidth controlled actuators (as coarse or fine adjusters or with relatively equal adjustment speeds) as a The bandwidth selects the actuator (control center) to select the bandwidth. Alternatively, the dtMOPA bandwidth selection actuator can only be used for fine adjustments, so that from other operational perspectives (eg, pulse energy stability, dose stability, or the like), there is no need to deviate significantly from the most Good dtMOPA.

Since the energy stability of a source laser amplifier laser (eg MOPA or MOPO) may be strongly influenced by the MO energy input to the PA/PO, it may be desirable to have individual voltage control for MO and PA/PO to adjust and control Independent of the MO energy output of the amplifier section, such as PA/PO.

An adjustable aperture may be rectangular to adjust within the short axis of the beam, which is generally horizontal in the applicant's transferee's laser system (eg, Cymer's 7XXX series or XLA or LXLR series laser systems) The adjustment of the direction of the direction is as shown in the example in Fig. 14 in the case where the line is narrowed by a laser. As described in Figure 15, the beam can be expanded to improve controllability prior to the adjustable aperture, such as with a beam expander 612, a chirp or a majority One lens, or one lens combination, and the like. After a portion of the beam is selected by the adjustable aperture, it (as noted above) can be expanded/compressed and collimated to meet the beam size requirements of the PA or PO (eg, within the adjustable beam expansion collimator) This can, for example, be a telescope or an adjustable telescope with an independent collimating lens. Beam spreading may not be required for a MOPO configuration where the beam size in the region of the amplifier electrodes during discharge between the electrodes may not be as important as in a (complex) fixed channel amplifier. The beam shaping optics may also be, for example, a combination of one of the cylindrical lenses having a distance between the two tuned lenses. For symmetric spectrum control, the center of an adjustable aperture can be adjusted to the center of the beam. For asymmetric spectral control, the center of the adjustable aperture can be moved within one axis (e.g., in a horizontal direction toward one edge or the other edge of the beam) to, for example, increase or decrease wavelength.

For some interference with a laser operating parameter (eg, related to beam quality, such as bandwidth), the change is more likely to occur in the vertical direction of the beam. As an example of repetition rate dependent interference, this is true. Thus, the variable aperture described in Figure 14 can be rotated 90° in the plane of the described page and one of the beam is selected for the beam quality parameter selection (e.g., bandwidth selection). This can also be performed using another aperture just described in connection with a selection aperture in Figure 14.

For some applications, the variable amplification line narrowing module 502 can echo the signals generated by the bandwidth measurement module 516. The variable amplification line narrowing module 502 can be used for coarse bandwidth control, utilizing one or both of the bandwidth control rotatable ports 520, 522, 524, and/or 526 and another bandwidth control actuation (e.g., differential emission time (dtMOPA) or grating bending, such as a bandwidth control device ("BCD") grating deformer) schematically shown in 630 in Figure 7, or one inside or outside the resonant cavity Variable aperture can be used for fine bandwidth control. Each of the bandwidth selective actuators can be used in conjunction with any one or more of the other actuators as one or the other of a coarse control actuator and a fine control actuator .

It will be apparent to those skilled in the art that the above-described embodiments of the subject matter disclosed above are intended to satisfy the requirements of at least the consistent embodiments of the subject matter of the disclosure. The exemplary embodiments are not intended to limit the scope of any claims, and are not intended to It will be apparent to those skilled in the art that many changes and modifications can be made to the disclosed aspects of the disclosed embodiments of the subject matter disclosed herein. Description of the object. The scope of the appended claims is intended to cover the scope of the embodiments of the claimed subject matter, and such equivalents and other modifications and variations are apparent to those of ordinary skill in the art. Other variations and modifications can be implemented in addition to the above-described changes and modifications of the disclosed subject matter disclosed herein.

80‧‧‧Interference

82‧‧‧fine actuation range

84‧‧‧Rough actuation range

158‧‧‧Adjustable aperture

200‧‧‧Laser System Controller

202‧‧‧FCP

204‧‧‧FCC

206‧‧‧LCP

210‧‧‧BAM

212‧‧‧LAM

220‧‧‧Bandwidth Control Module

222‧‧‧Variable amplification line narrowing module

232‧‧ ‧ step order

234‧‧‧Adder

236‧‧‧ sample delay

240‧‧‧Interference block

242‧‧‧Adder

244‧‧‧sample delay block

246‧‧‧Adder

247‧‧‧ Noise Block

248‧‧‧ Constant Square

249‧‧‧ Output

250‧‧‧ Bandwidth Controller

252‧‧‧Bandwidth target

254‧‧‧Measured bandwidth

256‧‧‧wavelength TIR

257‧‧‧ Processor

258‧‧‧Adder

260‧‧‧ noise filter

262‧‧‧Do not feel hysteresis control block

264‧‧‧Control mode selector

266‧‧‧ plus and minus squares

268‧‧‧Target change detector

270‧‧‧ Multiplier

272‧‧‧Control Gain Amplifier

274‧‧‧Command saturated block

276‧‧‧step smoother

278‧‧‧Target change cyclotron stepper amplifier

280‧‧‧ three-pole switch

284‧‧ ‧ step order

290‧‧‧Enter

292‧‧‧Absolute value function block

294‧‧‧ Forwarding Block

296‧‧‧ output

340‧‧‧ divider

342‧‧‧Adder

344‧‧‧sample delay

346‧‧‧Multiplier Block

348‧‧‧Adder

350‧‧‧Into the box

352‧‧‧

354‧‧‧Absolute value box

356‧‧‧Multiplier Block

358‧‧‧Adder

360‧‧‧ interception block

364‧‧‧Adder

366‧‧‧sample delay block

368‧‧‧ Delay Block

370‧‧‧Adder

500‧‧‧Multi-level gas discharge laser

502‧‧‧Variable amplification line narrowing module

504‧‧‧First stage chamber

506‧‧‧First Stage Output Coupler

508a‧‧‧steering optics

508b‧‧‧Steeling optics

510‧‧‧Input Coupler

512‧‧‧Second stage chamber

514‧‧‧beam splitter

516‧‧‧Bandwidth Measurement Module

518‧‧‧Discharge timing control module

520‧‧‧稜鏡

522‧‧‧稜鏡

524‧‧‧稜鏡

526‧‧‧稜鏡

528‧‧‧Raster

540‧‧‧R _MAX mirror

600‧‧‧Adjustable Beam Expanding Collimator

610'‧‧‧Adjustable aperture

612‧‧‧beam expander

620‧‧‧ Bandwidth Controller

630‧‧‧ Bandwidth Control Equipment

Figure 1 shows a bandwidth control device E ₉₅ sensitivity curve; Figure 2 depicts the interference type and time scale and amplitude of the layer according to one embodiment of the disclosed subject matter; Figure 3 is schematic and block The diagram shows a multi-stage gas discharge laser system with a variable amplification line narrowing module and differential emission time (dtMOPA) bandwidth control in accordance with one embodiment of the disclosed subject matter; Figure 4 Illustratively and in block diagram form an embodiment having four turns and a grating in accordance with a layer of one embodiment of the disclosed subject matter, wherein at least one turn can be rotated to increase/decrease the beam width, Thereby changing the bandwidth; Figure 5 depicts the overall architecture of a laser control system that can be used at the level of one of the disclosed embodiments; Figure 6 is a schematic and block diagram depicting one of the disclosed targets A representative laser system of the embodiment controls "implantation"; Figure 7 schematically and in block diagram form a bandwidth controller in accordance with one aspect of the disclosed embodiment; Figure 8 Schematic and block diagram The form describes a firing smoother in accordance with the level of one embodiment of the disclosed subject matter; FIG. 9 is a schematic and block diagram depicting a non-inductive hysteresis in accordance with the level of one embodiment of the disclosed subject matter. Figure 10 is a schematic and block diagram depicting a control mode selector in accordance with the level of one embodiment of the disclosed subject matter; Figure 11 is schematically and in block diagram depicting the disclosure according to the disclosure Example of a level having a plurality of Example Prism and a central wavelength selective mirror subject to one embodiment; FIG. 12 E ₉₅ describes the use of a bandwidth control center of △ t _MOPA; FIG. 13 schematically depicts the A variable amplification LNM according to a level of an embodiment of the disclosed subject matter; Figure 14 is a schematic and block diagram depicting an adjustable aperture bandwidth control in accordance with a level of an embodiment of the disclosed subject matter Actuator (control center); Figure 15 shows schematically and in block diagram form a bandwidth control system in accordance with the level of one of the disclosed embodiments; and Figure 16 illustrates the aperture through which the beam passes. size Examples of dependent bandwidth changes.

250‧‧‧ Bandwidth Controller

252‧‧‧Bandwidth target

254‧‧‧Measured bandwidth

256‧‧‧wavelength TIR

257‧‧‧ Processor

258‧‧‧Adder

260‧‧‧ noise filter

262‧‧‧Do not feel hysteresis control block

264‧‧‧Control mode selector

266‧‧‧ plus and minus squares

268‧‧‧Target change detector

270‧‧‧ Multiplier

272‧‧‧Control Gain Amplifier

274‧‧‧Command saturated block

276‧‧‧step smoother

278‧‧‧Target change cyclotron stepper amplifier

280‧‧‧ three-pole switch

284‧‧ ‧ step order

Claims (66)

A method for controlling bandwidth in a laser system, the laser system comprising: a gas discharge source laser having a cavity and generating a source laser output; a gas discharge amplifier laser, amplifying the source The laser output and produces a laser system output; a bandwidth metric unit that measures the bandwidth of the laser system output and provides a bandwidth measurement; and a bandwidth error signal generator that receives the bandwidth measurement and a bandwidth set point and Providing a bandwidth error signal; a variable amplification line narrowing unit, located in the cavity of the source laser, comprising a grating and a variable beam amplifying optical system; a differential timing controller, selecting the source A timing of a discharge of a discharge between a pair of electrodes within the laser and a pair of electrodes within the laser of the amplifier; the method comprising the steps of: controlling bandwidth using a bandwidth controller having at least two A mode of amplification control, including an independent mode to adjust the amplification of the beam within the line narrowing unit to a selected value independent of the bandwidth error signal And a feedback mode adjusting the amplification of the beam within the line narrowing unit based on the bandwidth error signal; and wherein in each mode, the differential timing controller selects the timing based on the bandwidth error signal or does not consider the Bandwidth error signal. The method of claim 1, wherein: adjusting the amplification of the beam in the line narrowing unit according to the bandwidth error signal comprises: continuing to adjust the amplification of the beam in the line narrowing unit Until the bandwidth crosses the inner bandwidth non-sensing value along a first direction, and only adjusts the spectral line narrower after the bandwidth crosses the output bandwidth non-sensitive band value in a second direction opposite to the first direction. Amplification of the beam within the unit. The method of claim 1, further comprising the steps of: using two modes of bandwidth error reduction; a first normal bandwidth error reduction mode, wherein the bandwidth controller performs a bandwidth error reduction command so as not to greatly Activating another laser system operating parameter in addition to the bandwidth; and a second bandwidth target variation error reduction mode, wherein the bandwidth controller performs a bandwidth error reduction command to change to a new bandwidth target, regardless of the other mine The impact on the operational parameters of the radio system; and when the bandwidth target produces a change, the bandwidth controller switches to the second error reduction mode, and when the new bandwidth target is reached, switches to the first error reduction mode. The method of claim 1, further comprising the step of allowing a minimum number of steps in a first direction before limiting the bandwidth actuation by performing any step in a second opposite direction Jitter. The method of claim 1, further comprising the step of: based on an error between the measured bandwidth and the new target bandwidth for a selected amount of time, when the bandwidth target is changed, The bandwidth controller is driven to the new bandwidth target and signaling indicates that the laser system is not considered to be within specifications for the selected amount of time. The method of claim 1, further comprising: using a function generator to command a bandwidth selection to actuate the stepper. The method of claim 6, wherein the function generator commands the bandwidth selection actuator based on an arbitrary function of the number of shots. The method of claim 1, wherein the bandwidth controller comprises a bandwidth selection actuator step command smoother. A laser system comprising: a gas discharge source laser having a cavity and generating a source laser output; a gas discharge amplifier laser amplifying the source laser output and generating a laser system output; a bandwidth metric unit that measures a bandwidth of the output of the laser system and provides a bandwidth measurement value; and a bandwidth error signal generator that receives the bandwidth measurement value and a bandwidth set point and provides a bandwidth error signal; a variable amplification line a narrowing unit located in the cavity of the source laser Including a grating and a variable beam amplifying optical system; a differential timing controller that selects a discharge between a pair of electrodes in the source laser and a pair of electrodes in the laser of the amplifier Timing of transmission; a bandwidth controller having at least two modes of amplification control, an independent mode for the bandwidth controller to control the variable amplification line narrowing unit to drive the amplification to a selected independent of the bandwidth error signal And a feedback mode for the bandwidth controller to control the variable amplification line narrowing unit to select the bandwidth of the laser system output based on the bandwidth error signal; and wherein the differential timing controller is based on the bandwidth error signal This timing is selected or the bandwidth error signal is not considered. The method of claim 1, wherein the bandwidth controller is configured to operate in an uncontrolled mode in which the line narrowing unit does not control amplification of the beam. The method of claim 1, wherein the step of adjusting the amplification of the light beam in the line narrowing unit according to the bandwidth error signal comprises: starting control only when the bandwidth leaves an outer bandwidth non-sensitive band value And stop the control when the bandwidth returns to an intraband bandwidth insensitive value. The method of claim 8, wherein the bandwidth selection actuator step command smoother is configured to limit the ratio of the laser beam amplification to adjustment. The system of claim 9, wherein the bandwidth controller comprises a bandwidth selection actuator step command smoother. The system of claim 9, wherein the bandwidth controller is configured to operate in an uncontrolled mode in which the line narrowing unit does not control the amplification of the beam. The system of claim 9, wherein the variable beam amplifying optical system comprises a set of four turns. The system of claim 15 wherein at least one of the tethers is rotatable. A system as claimed in claim 15 wherein at least one of the tethers is fixed. A method for controlling bandwidth within a laser system having a source laser and an amplifier laser that amplifies an output of one of the source lasers, the method comprising the steps of: based on a laser system output center a received measurement of the wavelength, controlling a center wavelength of the output of the laser system; and controlling the bandwidth by adjusting a variable amplification line in one of the cavity of the source laser One of the laser beams is amplified, wherein adjusting the laser beam amplification includes limiting the ratio of the laser beam amplification to a value that can limit the impact of the central wavelength control And adjusting the timing of the emission of a discharge between the electrode of the source laser and the electrode of the amplifier. The method of claim 18, further comprising: receiving a measurement of a bandwidth of an output of the laser system, and determining a bandwidth error signal based on the bandwidth measurement and a bandwidth set point. The method of claim 19, wherein adjusting the laser beam amplification in the variable amplification line narrowing unit comprises adjusting according to the determined bandwidth error signal. The method of claim 18, wherein limiting the magnification ratio adjustment comprises separating the amplification adjustment steps in a single feedback control loop over time or number of shots. The method of claim 18, wherein adjusting the timing of the discharge emission comprises adjusting the timing based on a bandwidth error signal. The method of claim 18, wherein adjusting the timing of the discharge emission comprises adjusting the timing regardless of a bandwidth error signal. The method of claim 17, wherein the adjusting the amplification of the laser beam comprises the steps of: initiating bandwidth control only when the bandwidth leaves an outer bandwidth non-sensing value; and not feeling bandwidth when the bandwidth returns to an inner band Stop bandwidth control when with value. A laser system comprising: a source laser having a cavity and generating a source laser output; amplifying the laser output of the source and generating a laser output of the laser; and a variable amplification line a narrowing unit located in the cavity of the source laser a variable beam amplifying optical system comprising a grating and receiving a source laser beam; a differential timing controller configured to select a pair of electrodes within the source laser and the laser within the amplifier a timing of emission of a discharge between the pair of electrodes; and a bandwidth controller configured to adjust amplification of one of the source laser beams in the variable amplification line narrowing unit to select the mine The bandwidth of the system output, the bandwidth controller includes a bandwidth selection actuator step command smoother. The system of claim 25, further comprising: measuring a bandwidth of the output of the laser system and providing a bandwidth metric unit of a bandwidth measurement; and receiving the bandwidth measurement and a bandwidth set point and providing a One of the bandwidth error signals is a bandwidth error signal generator. The system of claim 26, wherein the bandwidth controller is configured to adjust amplification of the source laser beam based on the bandwidth error signal. The system of claim 25, wherein the differential timing controller selects the timing based on a bandwidth error signal. The system of claim 25, wherein the differential timing controller selects the timing without considering a bandwidth error signal. The system of claim 25, further comprising a central wavelength controller configured to control one of the central wavelengths of the output of the laser system based on the measured value of one of the received center wavelengths of the laser system. The system of claim 25, wherein the step command smoother is configured to amplify the source laser beam by a ratio that is limited to a limit on the control of a central wavelength. A value. The system of claim 31, wherein the bandwidth controller further includes a command saturation block that determines a number of steps required to adjust amplification of the source laser beam, and the step is smoothed. The receiver receives the determined number of steps from the saturated block of the command. A laser system comprising: a laser source comprising: a source laser defining an optical cavity that produces a source output beam; an amplifier laser; and a bandwidth metric module that measures a thunder generated by the source Outputting a bandwidth of the optical pulse beam pulse and generating a bandwidth measurement value; a bandwidth error signal generator receiving the bandwidth measurement value and a bandwidth set point and providing a bandwidth error signal; an adjustable aperture located at the source laser External to the cavity and responsive to the bandwidth measurement, a spatial portion of the source output beam is selected to selectively vary the bandwidth of the source laser output, and the portion of the space is incident on the amplifier laser It is magnified there; and a beam expanding system that expands the size of the source output beam incident on the adjustable aperture. The laser system of claim 33, further comprising: a bandwidth selection actuator cooperated with the adjustable aperture to select Select one of the bandwidths of the laser system. The laser system of claim 34, wherein the bandwidth selective actuator comprises a differential emission timing system that adjusts a differential transmission time between the source laser and the amplifier laser. The laser system of claim 35, wherein: the adjustable aperture comprises a coarse bandwidth control actuator and the differential emission timing system comprises a fine bandwidth control actuator. The laser system of claim 33, wherein: the adjustable aperture comprises a coarse bandwidth control actuator and the beam expansion system comprises a fine bandwidth control actuator. The laser system of claim 33, wherein: the adjustable aperture comprises a thin bandwidth control actuator and the beam expansion system comprises a coarse bandwidth control actuator. The laser system of claim 33, further comprising: a bandwidth control device configured to modify the shape of the source output beam before entering the adjustable aperture. The laser system of claim 39, wherein: the adjustable aperture comprises a coarse bandwidth control actuator and the bandwidth control device comprises a thin bandwidth control actuator. The laser system of claim 39, wherein: the adjustable aperture comprises a thin bandwidth control actuator and the bandwidth control device comprises a coarse bandwidth control actuator. The laser system of claim 33, further comprising: a beam expander located at the adjustable aperture and the laser of the amplifier Meanwhile, the beam expander is configured to adjust the size of the beam space portion entering the laser of the amplifier. The laser system of claim 34, further comprising: a beam expander positioned between the adjustable aperture and the amplifier laser, wherein the beam expander is configured to adjust a beam entering the amplifier The size of the space part. The laser system of claim 42, further comprising: a beam collimator positioned between the adjustable aperture and the amplifier laser, wherein the beam collimator is configured to collimate into the The beam space portion of the amplifier's laser. The laser system of claim 43, further comprising: a beam collimator positioned between the adjustable aperture and the amplifier laser, wherein the beam collimator is configured to collimate into the The beam space portion of the amplifier's laser. The laser system of claim 44, wherein the beam expander and the beam collimator are part of a beam size adjustment collimator. A laser device comprising: a source laser defining an optical cavity that produces an output; an amplifier laser that receives and amplifies the output of the source laser and provides a laser system output; a bandwidth metric mode Group, measuring the laser output bandwidth and providing a bandwidth measurement; a central wavelength measurement module, measuring the laser output center wavelength and providing Providing a center wavelength measurement; a differential timing system that echoes the bandwidth measurement to selectively adjust a differential emission time between the source laser and the amplifier; a dispersive optical component; Responding to the bandwidth measurement to rotate relative to the dispersive optical element and selectively varying the laser output bandwidth; and second and third turns, which are responsive to the central wavelength measurement relative to the dispersive optics The component rotates and selectively changes the center wavelength. The apparatus of claim 47, wherein the differential timing system adjusts the differential transmission time to maintain a bandwidth within a selected range of one of the bandwidths. The device of claim 47, wherein the second and third turns comprise a coarse center wavelength selection 稜鏡 and a fine center wavelength selection 稜鏡. The device of claim 48, wherein the second and third turns comprise a coarse center wavelength selection 稜鏡 and a fine center wavelength selection 稜鏡. The apparatus of claim 47, further comprising: an incident angle of the second and third pupils adjusting the light beam on the dispersing optical element. The apparatus of claim 48, further comprising: an incident angle of the second and third pupils adjusting the light beam on the dispersing optical element. The device of claim 47, further comprising: the system selectively adjusting the differential transmission time, including a fine bandwidth control adjustment; and the first detour should be a bandwidth measurement relative to the dispersion The optics rotate, including a coarse bandwidth control adjustment. The device of claim 51, further comprising: the system selectively adjusting the differential transmission time, including a fine bandwidth control adjustment; and the first bypass response bandwidth measurement relative to the Dispersing optics rotates, including a coarse bandwidth control adjustment. The apparatus of claim 52, further comprising: the system selectively adjusting the differential transmission time, including a fine bandwidth control adjustment; and the first roundabout should be a bandwidth measurement relative to the dispersion The optics rotate, including a coarse bandwidth control adjustment. A laser device comprising: a source laser defining an optical cavity that produces an output; an amplifier laser that receives and amplifies the output of the source laser and provides a laser system output; a bandwidth metric mode a group that measures the laser output bandwidth and provides a bandwidth measurement; a central wavelength measurement module that measures the center wavelength of the laser output and provides a center wavelength measurement; a differential timing system that responds to the bandwidth measurement with selectivity Ground adjustment a differential emission time between the source laser and the amplifier; a dispersive optical element; a first turn that returns a bandwidth measurement to rotate relative to the dispersive optical element and selectively changes the thunder An output bandwidth; and a second chirp and mirror that echoes the central wavelength measurement to rotate relative to the dispersive optical element and selectively change the center wavelength. The device of claim 56, wherein the differential timing system adjusts the differential transmission time to maintain a bandwidth within a selected range of bandwidth. The device of claim 56, wherein the second ridge and the mirror comprise a coarse center wavelength selector and a fine center wavelength selector. The device of claim 57, wherein the second ridge and the mirror comprise a coarse center wavelength selector and a fine center wavelength selector. The device of claim 56, further comprising: a third germanium, operating in conjunction with the second germanium to select a central wavelength. The device of claim 57, further comprising: a third germanium, operating in conjunction with the second germanium to select a central wavelength. The device of claim 56, further comprising: the second ridge and the mirror adjusting an incident angle of the light beam on the dispersing optical element. The device of claim 58, further comprising: the second ridge and the mirror adjusting an incident angle of the light beam on the dispersing optical element. The apparatus of claim 56, further comprising: the system selectively adjusting the differential transmission time, including a fine bandwidth control adjustment; and the first detour should be a bandwidth measurement relative to the dispersion The optics rotate, including a coarse bandwidth control adjustment. The apparatus of claim 63, further comprising: the system selectively adjusting the differential transmission time, including a fine bandwidth control adjustment; and the first detour should be a bandwidth measurement relative to the dispersion The optics rotate, including a coarse bandwidth control adjustment. The apparatus of claim 62, further comprising: the system selectively adjusting the differential transmission time, including a fine bandwidth control adjustment; and the first round-trip bandwidth measurement value relative to the dispersion The optics rotate, including a coarse bandwidth control adjustment.