Forming multiple spatial images in a single lithography exposure pass.

Abstract

A method for controlling the energy of a pulsed light beam is described, the method including: generating a plurality of mixed sets of pulses of a light beam from a light source, each set of light beam pulses associated with a distinct dominant wavelength and a distinct target energy, receiving a measurement of the energy of a preceding pulse of the light beam, determining an energy error including comparing the measured energy of the preceding light beam pulse if the preceding light beam pulse is within a particular set of light beam pulses to a particular target energy associated with the particular set of light beam pulses, and adjusting at least one component of the light source, thereby adjusting the energy of a subsequent pulse within the particular set of light beam pulses based on the determined energy error.

Description

[Technical Field]

[0001] Cross-reference of related applications

[0001] This application claims priority to U.S. Patent Application No. 63 / 176,646, filed on 19 April 2021, titled "Forming Multiple Aerial Images in a Single Lithography Exposure Pass," which is incorporated herein by reference in its entirety.

[0002]

[0002] This disclosure relates to forming multiple spatial images in a single lithography exposure pass. The techniques described below may be used, for example, to form three-dimensional semiconductor components. [Background technology]

[0003]

[0003] Photolithography is a process in which semiconductor circuit configurations are patterned onto a substrate such as a silicon wafer. The photolithography light source provides deep ultraviolet (DUV) light used to expose the photoresist on the wafer. The DUV light for photolithography is generated by an excimer light source. Often, the light source is a laser source, and the pulsed light beam is a pulsed laser beam. The light beam is passed through a beam delivery unit, reticle, or mask, and then projected onto the prepared silicon wafer. In this way, the chip design is patterned onto the photoresist, which is then etched and cleaned, and then this process is repeated. [Overview of the project]

[0004]

[0004] In some general embodiments, a method for controlling the energy of a pulsed light beam is described. This method includes generating pulses of a plurality of mixed sets of light beams from a light source, each set of light beam pulses associated with a distinct dominant wavelength and a distinct target energy; receiving the results of a measurement of the energy of a preceding pulse of the light beam; determining an energy error, including comparing the measured energy of the preceding light beam pulse with a specific target energy associated with the particular set of light beam pulses if the preceding light beam pulse is within a particular set of light beam pulses; and adjusting at least one component of the light source, thereby adjusting the energy of a subsequent pulse within a particular set of light beam pulses based on the determined energy error.

[0005]

[0005] Several implementations may include one or more of the following features. For example, the method may include receiving each individual target energy associated with each set of light beam pulses. The method may include categorizing whether a preceding light beam pulse is within a particular set of light beam pulses. The method may include determining the amount of adjustment for at least one component of the light source. The method may include correcting the amount of adjustment for at least one component of the light source based on whether a preceding light beam pulse is within a particular set of light beam pulses.

[0006]

[0006] At least one component of the light source can be adjusted by changing the voltage supplied to an electrode associated with the light oscillator of the light source.

[0007]

[0007] In other common embodiments, the system includes a light source device and an energy control device that communicates with the light source device. The light source device includes an optical oscillator configured to generate optical pulses having spectral characteristics in response to an excitation signal, and a spectral modifier configured to control the spectral characteristics of the optical pulses. The energy control device is configured to determine a target energy associated with the spectral characteristics of the generated optical pulses, and to determine, at least on the determined target energy, to modulate the excitation signal to cause the optical oscillator to generate one or more subsequent optical pulses to compensate for changes in the configuration of the spectral modifier.

[0008]

[0008] Several implementations may include one or more of the following features. For example, tuning of the excitation signal may cause tuning of the energy of one or more subsequently generated optical pulses.

[0009]

[0009] The target energy associated with the spectral characteristics of the generated light pulse can be defined in advance in relation to the spectral characteristics of the generated light pulse.

[0010]

[0010] The optical oscillator may be associated with a plurality of transfer functions, each transfer function being associated with a specific configuration of the spectral tuning device and a specific value of the spectral characteristics. The energy control device may be configured to determine the adjustment of the excitation signal based on the transfer function associated with a specific configuration of the spectral tuning device used to generate one or more subsequent optical pulses.

[0011]

[0011] The spectral adjustment device may include at least one prism and diffracting elements arranged to communicate with each other optically, and each transfer function is associated with a different state of at least one prism.

[0012]

[0012] The spectral characteristics of an optical pulse may be the central wavelength of the optical pulse, and each component of the spectral adjustment device may correspond to a specific value of wavelength.

[0013]

[0013] The system may further include a measuring device configured to measure the energy of the light pulse. The energy control device may be configured to determine the energy error by comparing the target energy with the measured energy, and the decision to adjust the excitation signal may also be based on the energy error.

[0014]

[0014] The energy control device may be configured to determine the adjustment of the excitation signal that causes the optical oscillator to generate one or more subsequent optical pulses, by determining the adjustment of the excitation signal that causes the optical oscillator to generate one or more subsequent optical pulses associated with the spectral characteristics of the generated optical pulses.

[0015]

[0015] The energy control device may be configured to determine the target energy associated with the spectral characteristics of the generated light pulse by receiving a communication from a lithography exposure apparatus configured to receive the light pulse, the communication providing a set of target energies, each target energy in the set of target energies associated with a spectral characteristic.

[0016]

[0016] In other general embodiments, the energy control device includes a control module. The control module is configured to receive the energy value of a preceding light pulse emitted from a light source. The control module is configured to perform a comparison, which includes comparing the received energy value with a first target energy only if the preceding light pulse is in a first set of light beam pulses associated with a first dominant wavelength, or comparing the received energy value with a second target energy separate from the first target energy only if the preceding light pulse is in a second set of light beam pulses associated with a second dominant wavelength separate from the first dominant wavelength. The control module is configured to adjust at least one component of the light source based on this comparison, thereby adjusting the energy of a following light pulse having a dominant wavelength associated with the preceding light pulse.

[0017]

[0017] Several implementations may include one or more of the following features. For example, the control module may include a categorization module configured to categorize whether a preceding optical pulse is within a first set of optical beam pulses or within a second set of optical beam pulses. The control module may include a comparator configured to determine whether a preceding optical pulse is within a first set of optical beam pulses or within a second set of optical beam pulses, and to provide a first target energy or a second target energy based on this determination. The control module may include a signaling module configured to determine the amount of adjustment to be made to at least one component of the light source.

[0018]

[0018] The control module may include a compensation module configured to compensate for the amount of adjustment made to at least one component of the light source based on whether a preceding light pulse is within a first or second set of light beam pulses. The compensation module may be configured to compensate for the adjustment amount by applying a filter to the adjustment amount. The filter may include a notch filter that transmits information having frequencies within a first frequency band and substantially blocks information having frequencies outside the first frequency band. The filter may include a Kalman filter. The compensation module may be configured to compensate for the adjustment amount by applying feedforward compensation to the adjustment amount.

[0019] Based on this comparison, a control module configured to adjust at least one component of the light source, thereby adjusting the energy of a subsequent light pulse having a main wavelength associated with a preceding light pulse, may include transmitting a signal to the light source, thereby changing the voltage provided to an electrode associated with an optical oscillator of the light source. A control module configured to receive an energy value of a preceding light pulse may include a control module configured to receive energy values of a plurality of preceding light pulses emitted from the light source. The control module may be configured to adjust at least one component of the light source based on this comparison, thereby adjusting the energy of a plurality of subsequent light pulses having a main wavelength associated with a preceding light pulse. The control module may be configured to maintain the energy of a subsequent light pulse not having a main wavelength associated with a preceding light pulse based on this comparison.

Brief Description of the Drawings

[0020] [Figure 1A]

[0020] It is a block diagram of an example of an implementation form of a photolithography system. [Figure 1B]

[0021] It is a block diagram of an example of an implementation form of an optical system of the photolithography system in FIG. 1A. [Figure 1C]

[0022] It is a cross-sectional view of an example of a wafer exposed by the photolithography system in FIG. 1A. [Figure 2A]

[0023] It is a block diagram of another example of an implementation form of a photolithography system. [Figure 2B]

[0024] It is a block diagram of an example of an implementation form of a spectral feature selection module that can be used in a photolithography system. [Figure 2C]

[0025] It is a block diagram of an example of an implementation form of a fining module. [Figure 3A]

[0026] It is a plot of data related to the generation of pulses and / or bursts in a light source. [Figure 3B]

[0026] This is a plot of data related to the generation of pulses and / or bursts within the light source. [Figure 3C]

[0026] This is a plot of data related to the generation of pulses and / or bursts within the light source. [Figure 4]

[0027] This is a block diagram of another example of a photolithography system implementation. [Figure 5]

[0028] This is a flowchart illustrating an example of a process for forming three-dimensional semiconductor components. [Figure 6A]

[0029] An example of the optical spectrum of a single light pulse is shown. [Figure 6B]

[0029] An example of the optical spectrum of a single light pulse is shown. [Figure 7]

[0030] An example of the average optical spectrum of a single exposure pass is shown. [Figure 8A]

[0031] A side cross-sectional view of an example wafer is shown. [Figure 8B]

[0031] An example of a wafer is shown as a top cross-sectional view. [Figure 9A]

[0032] This shows a side cross-sectional view of an example of a three-dimensional semiconductor component. [Figure 9B]

[0032] An example of a three-dimensional semiconductor component is shown as a top cross-sectional view. [Figure 10A]

[0033] An example of simulation data is shown. [Figure 10B]

[0033] An example of simulation data is shown. [Figure 11A]

[0034] This is a block diagram of a photolithography system, where the control system includes an energy control module configured to provide an excitation signal to the light source, which is used to control electrodes in the light source's optical oscillator. [Figure 11B]

[0035] This is an illustration of an example of a transfer function TF of an optical oscillator (where the light energy is generated by a single optical oscillator depending on the excitation energy provided), showing how the light energy varies with the wavelength of the emitted pulsed light beam. [Figure 12]

[0036] This is a block diagram of the implementation configuration of the energy control module shown in Figure 11A, which is used in conjunction with the optical oscillator. [Figure 13]

[0037] This is a block diagram of an implementation configuration of a master oscillator that can constitute an optical oscillator. [Figure 14]

[0038] This table shows the correlation between each target energy having a possible dominant wavelength for the optical beam output from a light source including an optical oscillator. [Figure 15A]

[0039] This is a graph of the target energies for each of the four main wavelengths of the optical beam output from a light source, including an optical oscillator. [Figure 15B]

[0040] Figure 11 is a cross-sectional view of an example of a wafer being exposed in a photolithography system, where the optical beam output from a light source including an optical oscillator is generated at the four main wavelengths provided in Figure 15A. [Figure 16]

[0041] Figure 11A is a block diagram of an implementation configuration of the energy control module used with the optical oscillator, and includes multiple energy controllers (each energy controller is associated with the dominant wavelength of the optical beam output from the light source, including the optical oscillator). [Figure 17]

[0042] This is a block diagram showing an implementation of an energy controller that may be used in one or more of the energy control modules shown in Figures 11, 12, and 16. [Figure 18]

[0043] This is a block diagram showing an implementation of an energy controller that may be used in one or more of the energy control modules shown in Figures 11, 12, and 16. [Figure 19A]

[0044] Figure 11A is a block diagram of the implementation configuration of the energy control module used with the optical oscillator, and includes a feedforward energy controller. [Figure 19B]

[0045] Figure 19A is a block diagram of the implementation configuration of the feedforward energy controller. [Figure 19C]

[0046] Figure 19B is a block diagram showing the implementation configuration of the excitation decision module of the feedforward energy controller. [Figure 20]

[0047] Figure 11A is a block diagram of the implementation configuration of the energy control module used with the optical oscillator, and includes an iterative control energy controller. [Figure 21]

[0048] Figure 11A is a flowchart of the procedure performed by the photolithography system. [Modes for carrying out the invention]

[0021]

[0049] This specification describes a technique for forming three-dimensional semiconductor components by creating two or more spatial images on each different surface in a single lithography pass and using these spatial images.

[0022]

[0050] Referring to Figure 1A, the photolithography system 100 includes a light source 105 that provides a light beam 160 to a lithography exposure apparatus 169 that processes a wafer 170 housed in a wafer holder or stage 171. The light beam 160 is a pulsed light beam containing light pulses that are temporally separated from each other. The lithography exposure apparatus 169 includes a projection optics system 175 and a metrological system 172 through which the light beam 160 passes prior to reaching the wafer 170. The metrological system 172 may include, for example, a camera or other device capable of capturing an image of the wafer 170 and / or an image of the light beam 160 on the wafer 170, or a photodetector capable of capturing data describing the characteristics of the light beam 160 (such as the intensity of the light beam 160 on the wafer 170 in the xy plane). The lithography exposure apparatus 169 may be an immersion system or a dry system. The photolithography system 100 may also include a control system 150 for controlling the light source 105 and / or the lithography exposure apparatus 169.

[0023]

[0051] Microelectronic features are formed on the wafer 170 by, for example, exposing a layer of radiation-sensitive photoresist material on the wafer 170 with a light beam 160. See also Figure 1B, the projection optics system 175 includes a projection objective system comprising a slit 176, a mask 174, and a lens 177. The light beam 160 enters the optics system 175 and collides with the slit 176, and at least some of the beam 160 passes through the slit 176. In the example of Figures 1A and 1B, the slit 176 is rectangular and shapes the light beam 160 into an elongated rectangular light beam. A pattern is formed on the mask 174, and the pattern determines which parts of the shaped light beam are transmitted by the mask 174 and which parts are blocked by the mask 174. The design of the pattern is determined by the specific microelectronic circuit design to be formed on the wafer 170.

[0024]

[0052] The shaped light beam interacts with the mask 174. A portion of the shaped light beam transmitted by the mask 174 passes through the projection lens 177 (and may be focused by the projection lens 177) and exposes the wafer 170. The portion of the shaped light beam transmitted by the mask 174 forms a spatial image in the xy plane within the wafer 170. The spatial image is an intensity pattern formed by the light that reaches the wafer 170 after interacting with the mask 174. The spatial image is located on the wafer 170 and is generally stretched in the xy plane.

[0025]

[0053] System 100 can form multiple spatial images in a single exposure pass, each spatial image located in a spatially distinct location along the z-axis within the wafer 170. Referring also to Figure 1C, which shows a cross-sectional view of the wafer 170 in the yz-plane, the projection optics system 175 forms two spatial images 173a and 173b in different planes along the z-axis in a single exposure pass. As will be discussed in detail below, each of the spatial images 173a and 173b is formed from light having a different dominant wavelength.

[0026]

[0054] The location of the spatial image along the z-axis depends on the characteristics of the optical system 175 (including the projection lens 177 and the mask 174) and the wavelength of the light beam 160. The focal position of the lens 177 depends on the wavelength of the light incident on the lens 177. Therefore, it is possible to control the location of the spatial image by changing or otherwise controlling the wavelength of the light beam 160. By providing pulses with light of various dominant wavelengths in a single exposure pass, multiple (two or more) spatial images, each located at a different location along the z-axis, can be formed in a single exposure pass without moving the optical system 175 (or any component of the optical system 175) and the wafer 170 relative to each other along the z-axis.

[0027]

[0055] In the example in Figure 1A, light passing through the mask 174 is focused to the focal plane by the projection lens 177. The focal plane of the projection lens 177 is located between the projection lens 177 and the wafer stage 171, and the position of the focal plane along the z-axis depends on the characteristics of the optical system 175 and the wavelength of the light beam 160. The spatial images 173a and 173b are formed from light with different wavelengths, and therefore the spatial images 173a and 173b are located at different locations within the wafer 170. The spatial images 173a and 173b are separated from each other by a separation distance 179 along the z-axis. The separation distance 179 depends on the difference between the wavelength of the light forming spatial image 173a and the wavelength of the light forming spatial image 173b.

[0028]

[0056] The wafer stage 171 and mask 174 (or some other parts of the optical system 175) generally move relative to each other in the x, y, and z directions during scanning for routine performance correction and manipulation. For example, this movement can be used to achieve basic leveling, lens distortion compensation, and stage positioning error compensation. This relative movement is called incidental operational movement. However, in the system of Figure 1A, the relative movement between the wafer stage 171 and the optical system 175 is not relied upon to form the separation distance 179. Instead, the separation distance 179 is formed thanks to the ability to control the dominant wavelength in the pulse passing through the mask 174 during the exposure pass. Thus, unlike some conventional systems, the separation distance 179 is not generated simply by moving the optical system 175 and wafer 170 relative to each other along the z direction. Furthermore, both spatial images 173a and 173b exist on the wafer 170 during the same exposure pass. In other words, system 100 does not require that the spatial image 173a is formed in the first exposure pass and the spatial image 173b is formed in the second subsequent exposure pass.

[0029]

[0057] Light in the first spatial image 173a interacts with the wafer in portion 178a, and light in the second spatial image 173b interacts with the wafer in portion 178b. These interactions can form electronic features or other physical properties on the wafer 170, such as apertures or holes. Since the spatial images 173a and 173b are on different planes along the z-axis, they can be used to form three-dimensional features on the wafer 170. For example, spatial image 173a can be used to form a peripheral region, and spatial image 173b can be used to form channels, grooves, or recesses located at different locations along the z-axis. Thus, the techniques described herein can be used to form three-dimensional semiconductor components, such as three-dimensional NAND flash memory components.

[0030]

[0058] Before discussing additional details related to forming multiple spatial images in a single exposure pass, exemplary implementations of the light source 105 and the photolithography system 100 are described with reference to Figures 2A-2C, 3A-3C, and 4.

[0031]

[0059] Referring to Figure 2A, a block diagram of the photolithography system 200 is shown. The photolithography system 200 is an example of an implementation of system 100 (Figure 1A). For example, in the photolithography system 200, the light source 205 is used as the light source 105 (Figure 1A). The light source 205 generates a pulsed light beam 260 that is supplied to the lithography exposure apparatus 169. The light source 205 may be, for example, an excimer light source (which may be a laser beam) that outputs a pulsed light beam 260. Once in the lithography exposure apparatus 169, the pulsed light beam 260 is guided through the projection optics system 175 and projected onto the wafer 170. In this way, one or more microelectronic features are patterned onto the photoresist on the wafer 170, then developed and pre-cleaned prior to subsequent process steps, and this process is repeated. The photolithography system 200 also includes a control system 250, which, in the example shown in Figure 2A, is connected not only to the components of the light source 205 but also to the lithography exposure apparatus 169 in order to control various operations of the system 200. The control system 250 is an example of an implementation configuration of the control system 250 shown in Figure 1A.

[0032]

[0060] In the example shown in Figure 2A, the light source 205 is a two-stage laser system including a master oscillator (MO) 212 that provides a seed light beam 224 to a power amplifier (PA) 230. The MO 212 and PA 230 can be considered subsystems of the light source 205 or a system that is part of the light source 205. The power amplifier 230 receives the seed light beam 224 from the master oscillator 212 and amplifies the seed light beam 224 to generate the light beam 260 used in the lithography exposure apparatus 169. For example, the master oscillator 212 may emit pulsed seed light beams with a seed pulse energy of about 1 millijoule (mJ) per pulse, and these seed pulses can be amplified by the power amplifier 230 to about 10-15 mJ.

[0033]

[0061] The master oscillator 212 includes a discharge chamber 214 housing two elongated electrodes 217, a gain medium 219 which is a mixed gas, and a fan for circulating the gas between the electrodes 217. A resonator is formed between a thinning module 216 on the first side of the discharge chamber 214 and an output coupler 218 on the second side of the discharge chamber 214. The thinning module 216 may include diffractive optical elements such as a diffraction grating to fine-tune the spectral output of the discharge chamber 214. Figures 2B and 2C provide additional details regarding the thinning module 216.

[0034]

[0062] Figure 2B is a block diagram of an example implementation of a spectral feature selection module 258 that includes one or more instances of the thinning module 216. The spectral feature selection module 258 couples to light propagating within the light source 205. In some implementations (as shown in Figure 2B), the spectral feature selection module 258 receives light from the discharge chamber 214 of the master oscillator 212 to enable fine-tuning of spectral features such as wavelength and bandwidth within the master oscillator 212.

[0035]

[0063] The spectral feature selection module 258 may include a control module such as a spectral feature control module 254, which includes electronic components in any combination of firmware and software. The control module 254 is connected to one or more actuators, such as spectral feature actuators 255_1 to 255_n. Each of the actuators 255_1 to 255_n may include one or more actuators connected to each of the optical features 256_1 to 256_n of the optical system 257. The optical features 256_1 to 256_n are configured to adjust specific characteristics of the generated light beam 260, thereby adjusting the spectral features of the light beam 260. The control module 254 receives control signals from the control system 250, which include specific commands for operating or controlling one or more of the actuators 255_1 to 255_n. Actuators 255_1 to 255_n may be selected and designed to work together (i.e., in tandem), or they may be configured to work individually. Furthermore, each actuator 255_1 to 255_n may be optimized to respond to a particular class of disturbance.

[0036]

[0064] Each optical feature 256_1 to 256_n is optically coupled to a light beam 260 generated by a light source 105. The optical system 257 may be implemented as a thinning module 216C as shown in Figure 2C. The thinning module includes dispersive optical elements such as a reflection grating 291 and refractive optical elements such as prisms 292, 293, 294, and 295 as optical features 256_1 to 256_n. One or more of the prisms 292, 293, 294, and 295 may be rotatable. An example of this thinning module can be found in U.S. Patent Application No. 12 / 605,306, titled "SYSTEM METHOD AN APPARATUS FOR SELECTING AND CONTROLLING LIGHT SOURCE BANDWIDTH" (Application 306), filed on 23 October 2009 and granted on 27 March 2012 as U.S. Patent No. 8,144,739, which is incorporated by reference as if its entire contents were described. Application 306 describes a thinning module including a beam expander (including one or more prisms 292, 293, 294, 295) and dispersion elements such as a grating 291. The operating systems for each of the activatable optical features such as the grating 291 and one or more of the prisms 292, 293, 294, 295 are not shown in Figure 2C.

[0037]

[0065] Each actuator in the actuator systems 255_1 to 255_n is a mechanical device for moving or controlling each of the optical features 256_1 to 256_n of the optical system 257. The actuators receive energy from module 254 and convert that energy into several kinds of motion to be applied to the optical features 256_1 to 256_n of the optical system 257. For example, the 306 application describes actuator systems such as force devices (for applying force to several areas of a grating) and rotating stages for rotating one or more prisms of a beam expander. Actuator systems 255_1 to 255_n may include motors such as stepping motors, valves, pressure control devices, piezoelectric devices, linear motors, hydraulic actuators, and / or sound coils.

[0038]

[0066] Returning to Figure 2A, the master oscillator 212 also includes a line-centered analysis module 220 that receives the output light beam from the output coupler 218, and a beam-coupled optics system 222 that modifies the size or shape of the output light beam as needed to form a seed light beam 224. The line-centered analysis module 220 is a measurement system that can be used to measure or monitor the wavelength of the seed light beam 224. The line-centered analysis module 220 may be located elsewhere within the light source 205, or it may be located at the output of the light source 205.

[0039]

[0067] The gas mixture used in the discharge chamber 214 can be any gas suitable for generating a light beam at the wavelength and bandwidth required for application. With respect to the excimer source, the gas mixture may include, as a buffer gas, noble gases such as argon or krypton, halogens such as fluorine or chlorine, and trace amounts of xenon in addition to helium and / or neon. Specific examples of gas mixtures include argon fluoride (ArF) emitting light at a wavelength of approximately 193 nm, krypton fluoride (KrF) emitting light at a wavelength of approximately 248 nm, or xenon chloride (XeCl) emitting light at a wavelength of approximately 351 nm. The excimer gain medium (gas mixture) is pumped by short (e.g., nanosecond) current pulses within a high-voltage discharge by applying a voltage to the elongated electrode 217.

[0040]

[0068] The power amplifier 230 includes a beam coupling optical system 232 that receives a seed light beam 224 from a master oscillator 212 and directs the light beam through a discharge chamber 240 to a beam swivel optical element 248, which corrects or alters the direction of the seed light beam 224 so that it is returned into the discharge chamber 240. The discharge chamber 240 includes a pair of elongated electrodes 241, a gain medium 219 which is a mixed gas, and a fan for circulating the mixed gas between the electrodes 241.

[0041]

[0069] The output light beam 260 is guided through a bandwidth analysis module 262, in which various parameters of the output light beam 260 (such as bandwidth or wavelength) can be measured. The output light beam 260 may also be guided through a beam fabrication system 263. The beam fabrication system 263 may include, for example, a pulse extender, in which each pulse of the output light beam 260 is time-extended in, for example, an optical delay unit to adjust the performance characteristics of the light beam striking the lithography exposure apparatus 169. The beam fabrication system 263 may also include other components that can act on the beam 260: for example, reflective and / or refractive optical elements (such as lenses and mirrors), filters, and optical apertures (including an automatic shutter).

[0042]

[0070] The photolithography system 200 also includes a control system 250. In the implementation shown in Figure 2A, the control system 250 is connected to various components of the light source 205. For example, the control system 250 can control when the light source 205 emits an optical pulse, or a burst of optical pulses containing one or more optical pulses, by sending one or more signals to the light source 205. The control system 250 is also connected to the lithography exposure apparatus 169. Thus, the control system 250 can also control various aspects of the lithography exposure apparatus 169. For example, the control system 250 can control the exposure of the wafer 170 and thus can be used to control how electronic features are printed on the wafer 170. In some implementations, the control system 250 can control the scanning of the wafer 170 by controlling the movement of a slit 176 in the xy plane (Figure 1B). Furthermore, the control system 250 can exchange data with the metrological system 172 and / or the optical system 175.

[0043]

[0071] The lithography exposure apparatus 169 may also include, for example, a temperature control device (such as an air conditioning device and / or a heating device) and / or a power supply for various electrical components. The control system 250 may also control these components. In some implementations, the control system 250 is implemented to include two or more sub-control systems, each having at least one sub-control system (lithography controller) dedicated to controlling aspects of the lithography exposure apparatus 169. In these implementations, the control system 250 may be used to control aspects of the lithography exposure apparatus 169, either in place of or in addition to using a lithography controller.

[0044]

[0072] The control system 250 includes an electronic processor 251, electronic storage 252, and an I / O interface 253. The electronic processor 251 includes one or more processors suitable for executing computer programs, such as general-purpose or special-purpose microprocessors, and any one or more processors of any type of digital computer. Generally, the electronic processor receives commands and data from read-only memory, random-access memory, or both. The electronic processor 251 can be any type of electronic processor.

[0045]

[0073] The electronic storage 252 may be volatile memory such as RAM or non-volatile memory. In some implementations, the electronic storage 252 includes non-volatile parts or components and volatile parts or components. The electronic storage 252 may store data and information used in the operation of the control system 250, components of the control system 250, and / or systems controlled by the control system 250. The information may be stored, for example, in a lookup table or database. For example, the electronic storage 252 may store data indicating values ​​for various characteristics of the beam 260 under various operating conditions and performance scenarios.

[0046]

[0074] Furthermore, the electronic storage 252 may store various recipes or processing programs 259 that dictate the parameters of the light beam 260 during use. For example, the electronic storage 252 may store a recipe that specifies the wavelength of each pulse in the light beam 260 in a particular exposure pass. The recipe may specify various wavelengths for various exposure passes. The wavelength control techniques discussed below may be applied on a pulse-by-pulse basis. In other words, the wavelength content may be controlled with respect to each individual pulse in the exposure pass to facilitate the formation of a spatial image at a desired location along the z-axis.

[0047]

[0075] The electronic storage 252 may also store (perhaps as a computer program) commands that, when executed, cause the processor 251 to communicate with the control system 250, the optical system 205, and / or components within the lithography exposure apparatus 169.

[0048]

[0076] The I / O interface 253 is any type of electronic interface that enables the control system 250 to receive and / or provide data and signals to the operator, the optical system 205, the lithography exposure apparatus 169, any component or system within the optical system 205 and / or the lithography exposure apparatus 169 and / or an automated process running on another electronic device. For example, the I / O interface 253 may include one or more of a visual display, a keyboard, and a communication interface.

[0049]

[0077] The optical beam 260 (and optical beam 160) is a pulsed optical beam and may contain one or more bursts of pulses that are spaced apart in time. Each burst may contain one or more optical pulses. In some implementations, a burst may contain hundreds of pulses (e.g., 100-400 pulses). Figures 3A-3C provide an overview of pulse and burst generation within the light source 205. Figure 3A shows the amplitude of the wafer exposure signal 300 over time, Figure 3B shows the amplitude of the gate signal 315 over time, and Figure 3C shows the amplitude of the trigger signal over time.

[0050]

[0078] The control system 250 may be configured to transmit a wafer exposure signal 300 to the light source 205 in order to control the light source 205 and generate a light beam 260. In the example shown in Figure 3A, the wafer exposure signal 300 has a high value 305 (e.g., 1) for a certain period 307 during which the light source 205 generates bursts of light pulses. Otherwise, the wafer exposure signal 300 has a low value 310 (e.g., 0) when the wafer 170 is not exposed.

[0051]

[0079] Referring to Figure 3B, the light beam 260 is a pulsed light beam, and the light beam 260 includes bursts of pulses. The control system 250 also controls the duration and frequency of the pulse bursts by transmitting a gate signal 315 to the light source 205. The gate signal 315 has a high value 320 (e.g., 1) during the pulse burst and a low value 325 (e.g., 0) during the time between consecutive bursts. In the example shown, the period during which the gate signal 315 has a high value is also the burst period 316. The bursts are separated by a time interval between bursts. During the time interval between bursts, the lithography exposure apparatus 169 may place the next die on the wafer 170 for exposure.

[0052]

[0080] Referring to Figure 3C, the control system 250 also controls the repetition rate of pulses within each burst by trigger signals 330. Trigger signals 330 include triggers 340, one of which is provided to the light source 205 to cause it to generate light pulses. The control system 250 may send triggers 340 to the light source 205 each time a pulse is generated. Thus, the repetition rate of pulses generated by the light source 205 (the time between two consecutive pulses) can be set by trigger signals 330.

[0053]

[0081] As discussed above, when the gain medium 219 is pumped by applying a voltage to the electrode 217, the gain medium 219 emits light. When the voltage is applied to the electrode 217 in pulses, the light emitted from the medium 219 is also pulsed. Thus, the repetition rate of the pulsed light beam 260 is determined by the rate at which the voltage is applied to the electrode 217, and each application of voltage generates a light pulse. The light pulse propagates through the gain medium 219 and exits the discharge chamber 214 through the output coupler 218. Thus, a series of pulses are generated periodically, and the application of voltage to the electrode 217 is repeated. The trigger signal 330 can be used to control, for example, the repetition rate of the voltage application and pulses to the electrode 217 (which can be in the range of approximately 500 to 6,000 Hz in most applications). In some implementations, the repetition rate can be greater than 6,000 Hz, and may be greater than, for example, 12,000 Hz.

[0054]

[0082] Signals from the control system 250 may also be used to control electrodes 217 and 241 in the master oscillator 212 and power amplifier 230, respectively (for controlling the pulse energy of the master oscillator 212 and power amplifier 230, and therefore the energy of the light beam 260). There may be a delay between the signal supplied to electrode 217 and the signal supplied to electrode 241. The amount of delay may affect the characteristics of the beam 260, such as the amount of coherence in the pulsed light beam 260.

[0055]

[0083] The pulsed light beam 260 may have an average output power in the range of several tens of watts (e.g., approximately 50 W to approximately 130 W). The radiance of the light beam 260 at output (i.e., average power per unit area) is 60 W / cm². 2 ~90W / cm 2 It could be within the range.

[0056]

[0084] See also Figure 4, the wafer 170 is irradiated with a light beam 260. The lithography exposure apparatus 169 includes an optical system 175 (Figures 1A, 1B). In the example of Figure 4, the optical system 175 (not shown) includes an irradiator system 429 including an objective system configuration 432. The objective system configuration 432 includes a projection lens 177 (Figure 1B) and enables image transfer from the mask 174 to the photoresist on the wafer 170. The irradiator system 429 adjusts the range of angles of the light beam 260 that strikes the mask 174. The irradiator system 429 can also homogenize (uniformly) the intensity distribution of the light beam 260 in the xy plane across the entire mask 174.

[0057]

[0085] In some implementations, an immersion medium may be supplied to cover the wafer 170. The immersion medium may be a liquid (such as water) for immersion lithography. In other implementations where lithography is a dry system, the immersion medium may be a gas such as dry nitrogen, dry air, or clean air. In other implementations, the wafer 170 may be exposed in a pressure-controlled environment (such as a vacuum or partial vacuum).

[0058]

[0086] During an exposure pass, multiple N pulses of the light beam 260 illuminate the same area of ​​the wafer 170. N can be any integer greater than 1. The number N pulses of the light beam 110 illuminating the same area may be called the exposure window or exposure pass 400. The size of the window 400 can be controlled by a slit 176. For example, the slit 176 may include multiple blades that are movable to form an opening in one configuration and close an opening in another configuration. The size of the window 400 can also be controlled by arranging the blades of the slit 176 to form an opening of a specific size.

[0059]

[0087] The N pulses also determine the irradiation dose of the exposure pass. The irradiation dose is the amount of light energy delivered to the wafer during the exposure pass. Thus, the characteristics of the N pulses (such as the light energy in each pulse) determine the irradiation dose. Furthermore, as will be discussed in more detail below, the N pulses can also be used to determine the light intensity of each spatial image 173a and 173b. In particular, a recipe may specify N pulses, some of which have a first dominant wavelength that forms spatial image 173a, and some of which have a second dominant wavelength that forms spatial image 173b.

[0060]

[0088] In addition, the slit 176 and / or mask 174 can move in the scanning direction in the xy plane so that only a portion of the wafer 170 is exposed at a predetermined time or during a specific exposure scan (or exposure pass). The size of the area on the wafer 170 exposed by the light beam 160 is determined by the distance between the blades in the non-scanning direction and the length (distance) of the scan in the scanning direction. In some implementations, the value of N is in the tens (e.g., 10 to 100 pulses). In other implementations, the value of N is greater than 100 pulses (e.g., 100 to 500 pulses). The exposure field 479 of the wafer 170 is the physical area of ​​the wafer 170 that is exposed within one scan of the exposure slit or window in the lithography exposure apparatus 169.

[0061]

[0089] The wafer stage 171, mask 174, and objective system 432 are fixed to the associated operating system, thereby forming a scanning configuration. In the scanning configuration, one or more of the mask 174, objective system 432, and wafer 170 may move relative to each other in the xy plane (via the stage 171). However, apart from incidental relative maneuvering motion between the wafer stage 171, mask 174, and objective system 432, these elements do not move relative to each other along the z axis during or after the exposure pass.

[0062]

[0090] Referring to Figure 5, a flowchart of process 500 is shown. Process 500 is an example of a process for forming a three-dimensional semiconductor component or a part of such a component. Process 500 can be performed using a photolithography system 100 or 200. Process 500 is discussed in relation to system 200 shown in Figure 2A. Process 500 is also discussed in relation to Figures 6A to 10B.

[0063]

[0091] The light beam 260 is directed towards the mask 174 (510). The light beam 260 is a pulsed light beam containing multiple pulses, each temporally separated from one another, as shown in Figure 3C. Figures 6A and 6B show examples of the optical spectrum of a single pulse that is part of the light beam 260. Other pulses in the light beam 260 may have a variety of optical spectra.

[0064]

[0092] Referring to Figure 6A, the optical spectrum 601A of the light pulse 600A is shown. The light pulse 600A has a non-zero intensity within the wavelength band. The wavelength band can also be called the bandwidth of the light pulse 600A.

[0065]

[0093] The information shown in Figure 6A is the instantaneous optical spectrum 601A (or radiation spectrum) of pulse 600A. The optical spectrum 601A contains information about how the optical energy or power of the pulse of light beam 260 is dispersed across a wide range of wavelengths (or frequencies). The optical spectrum 601A is drawn in the form of a diagram where the spectral intensity (not necessarily absolutely calibrated) is plotted according to wavelength or optical frequency. The optical spectrum 601A may be called the spectral shape or intensity spectrum of the pulse of light beam 260. Pulse 600A has a dominant wavelength 602A, which is the peak intensity in the example in Figure 6A. Discussions of the pulse of light beam 260 and the spatial image formed by the pulse of light beam 260 refer to the dominant wavelength of the pulse, but the pulse includes wavelengths other than the dominant wavelength and has a certain bandwidth that can be characterized by a metric. For example, the total width (called FWXM) of spectrum 601A at a certain percentage (X) of the maximum peak intensity of the spectral shape can be used to characterize the light beam bandwidth. As another example, the spectral width containing a certain proportion (Y) of the integrated spectral intensity (called EY) can be used to characterize the optical beam bandwidth.

[0066]

[0094] Pulse 600A is shown as an example of a pulse that may exist within the optical beam 260. When pulse 600A is used to expose a portion of wafer 120, the light within the pulse forms a spatial image. The location of the spatial image in the z direction (Figures 1C and 4) is determined by the value of the dominant wavelength 602A. Various pulses within the optical beam 260 may have various dominant wavelengths. For example, to generate two spatial images in a single exposure pass, some pulses in the optical beam 260 may have one dominant wavelength (first dominant wavelength), and other pulses in the optical beam 260 may have another dominant wavelength (second dominant wavelength). The first and second dominant wavelengths are different wavelengths. The wavelength difference between the first and second dominant wavelengths may be called spectral separation. The spectral separation may be, for example, 200 femtometers (fm) to 50 picometers (pm). The wavelengths of various pulses within the optical beam 260 may be different, but the shape of the optical spectrum of the pulses may be the same.

[0067]

[0095] The light source 205 can dither or switch the dominant wavelengths between the first and second dominant wavelengths on a pulse-by-pulse basis so that every pulse has a different dominant wavelength than the pulse that immediately precedes or immediately follows it. In these implementations, assuming that all pulses in the light beam 260 have the same intensity, dispersing the first and second dominant wavelengths in this manner produces two spatial images at different locations in the z-direction with the same intensity.

[0068]

[0096] In some implementations, a certain portion of the pulse (e.g., 33%) has a first dominant wavelength, and the remainder (67% in this example) has a second dominant wavelength. In these implementations, assuming that all pulses in the optical beam 260 have the same intensity, two spatial images are formed with different intensities. The spatial image formed by the pulse with the first dominant wavelength has approximately half the intensity of the spatial image formed by the pulse with the second dominant wavelength. In this way, the dose delivered to a specific location in the wafer 170 along the z-axis can be controlled by controlling portions of N pulses, each having a first and a second dominant wavelength.

[0069]

[0097] The portion of the pulse that will have a specific dominant wavelength for an exposure pass may be defined in a recipe file 259 stored on electronic storage 252. Recipe 259 defines various dominant wavelength ratios for the exposure pass. Recipe 259 may also define ratios for other exposure passes, such that different ratios may be used for other exposure passes, and the spatial image may be adjusted or controlled on a field-by-field basis.

[0070]

[0098] Referring to Figure 6B, the optical spectrum 601B of pulse 600B is shown. Pulse 600B is another example of a pulse of light beam 260. The optical spectrum 601B of pulse 600B has a different shape from optical spectrum 601A. In particular, optical spectrum 601B has two peaks corresponding to the two main wavelengths 602B_1 and 602B_2 of pulse 600B. Pulse 600B is part of light beam 260. If pulse 600B is used to expose a portion of wafer 120, the light in the pulse forms two spatial images at different locations along the z-axis on the wafer. The locations of the spatial images are determined by the wavelengths of the main wavelengths 602B_1 and 602B_2.

[0071]

[0099] The pulses shown in Figures 6A and 6B can be formed by any hardware capable of forming such pulses. For example, a pulse train of pulses such as pulse 600A can be formed by using a thinning module similar to the thinning module 216C in Figure 2C. The wavelength of light diffracted by the grating 291 depends on the angle of incidence of the light incident on the grating. A mechanism for changing the angle of incidence of light interacting with the grating 291 may be used with such a thinning module to generate a pulse train having N pulses in an exposure pass, where at least one of the N pulses has a different dominant wavelength than the dominant wavelength of another pulse in the N pulses. For example, one of the prisms 292, 293, 294, and 295 can be rotated to change the angle of light incident on the grating 291 on a pulse-by-pulse basis. In some implementations, the thinning module includes a mirror that is in the path of the beam 260 and is movable to change the angle of light incident on the grating 291. One example of such an implementation is discussed, for instance, in U.S. Patent No. 6,192,064, issued on February 20, 2001, titled "NARROW BAND LASER WITH FINE WAVELENGTH CONTROL".

[0072]

[0100] Pulses such as pulse 600B (Figure 6B) can also be formed by using a thinning module similar to the thinning module 216C in Figure 2C. For example, an excited optical element such as an acousto-optic modulator may be placed within the thinning module 216C in the path of beam 260. The acousto-optic modulator deflects the incident light ray at an angle dependent on the frequency of the sound wave used to excite the acousto-optic modulator. The acousto-optic modulator includes a material such as glass or quartz that allows sound waves to propagate, and a transducer coupled to the material. The transducer vibrates in response to the excitation signal, and the vibration forms sound waves within the material. The sound waves form a moving surface of expansion and compression that changes the refractive index of the material. As a result, the sound waves act as a diffraction grating so that the incident light is diffracted and exits the material simultaneously at several different angles. Light of the second or higher order may be allowed to reach the grating 291, and light of each of the various diffraction orders has a different angle of incidence on the grating 291. In this way, a single pulse containing two or more dominant wavelengths can be formed. An example of a thinning module including an acoustic-optical modulator is discussed, for example, in U.S. Patent No. 7,154,928, issued December 26, 2006, titled "LASER OUTPUT BEAM WAVEFRONT SPLITTER FOR BANDWIDTH SPECTRUM CONTROL".

[0073]

[0101] A set of optical pulses is delivered through the mask 174 in the direction of the wafer 170 during a single exposure pass (520). As discussed above, N optical pulses may be delivered to the wafer 170 during the exposure pass. The N optical pulses may be continuous optical pulses in the beam 260. The exposed portion of the wafer 170 sees the average of the optical spectra of each pulse of the N pulses over the entire exposure pass. Thus, if some of the N pulses have a first dominant wavelength and the rest of the N pulses have a second dominant wavelength, the average optical spectrum of the wafer 170 will be an optical spectrum that includes peaks at the first dominant wavelength and peaks at the second dominant wavelength. Similarly, if all or some of the individual pulses of the N pulses have two or more dominant wavelengths, those dominant wavelengths may form several peaks in the average optical spectrum. Figure 7 shows an example of the average optical spectrum 701 in wafer 170. The average optical spectrum 701 includes a first dominant wavelength 702_1 and a second dominant wavelength 702_2. In the example shown in Figure 7, the first dominant wavelength 702_1 and the second dominant wavelength 702_2 are separated by a spectral separator 703 of approximately 500 fm, but other combinations may also be considered. The spectral separator 703 is configured such that the first dominant wavelength 702_1 and the second dominant wavelength 702_2 are distinct, and the mean optical spectrum 701 includes a spectral region 704 of low or zero intensity between wavelengths 702_1 and 702_2.

[0074]

[0102] Two or more spatial images (for example, a first spatial image based on a first dominant wavelength and a second spatial image based on a second dominant wavelength) are formed on wafer 170 based on the mean optical spectrum (530). Continuing with the example of the mean optical spectrum 701 and also referring to Figure 8A, two spatial images 873a and 873b are formed in a single exposure pass based on N pulses. The N pulses include a first set of pulses having a first dominant wavelength 702_1 and a second set of pulses having a second dominant wavelength 702_2. For example, these are single-peak pulses as shown in Figure 6A. The pulse having the first dominant wavelength 702_1 forms the first spatial image 873a, and the pulse having the second dominant wavelength 702_2 forms the second spatial image 873b. Spatial image 873a is formed on the first surface 878a, and spatial image 873b is formed on the second surface 878b. The planes 878a and 878b are perpendicular to the direction of propagation of the optical beam 260 on the wafer 170. The planes 878a and 878b are separated by a distance of 879 along the z-direction.

[0075]

[0103] The separation distance 879 is greater than the depth of focus of the lithography apparatus 169 with an average optical spectrum having a single dominant wavelength. The depth of focus can be defined with respect to the dose value (amount of light energy supplied to the wafer) as the range of focus along the z-direction provided by the dose for feature sizes within the tolerance range of the feature size of the process applied to the wafer 170. Process 500 can increase the depth of focus of the lithography apparatus 169 by providing two or more distinct spatial images on the wafer 170 during a single exposure pass. This is because each of the multiple spatial images can expose the wafer at different locations in the z-direction with features within the tolerance range of feature size. In other words, process 500 can provide the lithography apparatus 169 with a larger range of depth of focus during a single exposure pass. As discussed above, the operator of the lithography apparatus 169 can control various parameters of the exposure process via the recipe file 259. In some implementations, the operator of the lithography exposure apparatus 169 may receive information from a simulation program, such as Tachyon Source-Mask Optimization (SMO), available from Brion and ASML, and this information may be used to program or otherwise define the parameters of the recipe file 259. For example, the operator of the lithography exposure apparatus 169 may know that an upcoming lot will not require the same depth of focus as a previously exposed lot. In this example, the operator may define the depth of focus and dose variation to the simulation program, and the simulation program will return a value for spectral separation 703 to achieve the desired parameters. The operator may then define the value for spectral separation 703 for the upcoming lot by programming the recipe file 259 via the I / O interface 253. In some implementations, the operator may use the simulation to determine whether a greater depth of focus (which can be achieved by exposing the wafer 170 with multiple spatial images on separate planes) is required for a particular exposure pass.In cases where a greater depth of field is not required to form a particular portion of the semiconductor component, recipe file 259 may be constructed such that the exposure pass used to form that particular portion of the semiconductor component has an average optical spectrum containing a single dominant wavelength.

[0076]

[0104] Furthermore, the operator and / or simulator may receive information about the formed three-dimensional part measured by the metrological system 172 or another sensor. For example, the metrological system 172 may provide data relating to the sidewall angle of the formed 3D semiconductor part, and this data may be used to program parameters in the recipe file 259 for subsequent exposure passes.

[0077]

[0105] Figure 8B shows the spatial image 873a in the xy plane (looking within the page plane of Figure 8A) on surface 878a. The spatial images 873a and 873b are generally two-dimensional intensity patterns formed in the xy plane. The properties of the intensity patterns depend on the properties of the mask 174. The first and second surfaces 878a and 878b are parts of the wafer 170. As shown in Figure 8B, the first surface 878a may be only a small portion of the entire wafer 170.

[0078]

[0106] The value of the separation distance 879 depends on the spectral separation 703 and the characteristics of the optical system 275. For example, the value of the separation distance 879 may depend on the focal length, aberration, and other characteristics of the lenses and other optical elements in the optical system 275. For a scanner lens having chromatic aberration C, the separation distance 879 can be determined from the following equation 1: ΔD = C * Δλ Equation (1) Here, ΔD is the separation distance in nanometers (nm) 879, C is the chromatic aberration (defined as a distance, where the focal plane moves in the direction of propagation of the wavelength change: this is a known property of projection lens 177), and Δλ is the spectral separation distance in picometers 873. For lens 177 with a value of C = 500 nm / pm, the spectral separation distance 873 can be approximately 10 fm in order to achieve a focal separation distance 875 of 5000 nm (5 μm).

[0079]

[0107] Furthermore, due to variations in the manufacturing and installation processes and / or modifications made by the end user, various dominant wavelengths may be required to achieve a desired separation distance 879 for a particular instance of a certain type of exposure apparatus 169. As discussed above, the recipe or process control program 259 may be stored on the electronic storage 252 of the control system 250. The recipe 259 may be modified or programmed to be customized for a particular exposure apparatus or a certain type of exposure apparatus. The recipe 259 may be programmed when the lithography apparatus 200 is manufactured, and / or the recipe 259 may be programmed by the end user or by another operator familiar with the performance of the system 200, for example, via the I / O interface 253.

[0080]

[0108] Recipe 259 may also specify various spacing distances 879 for various exposure passes used to expose different areas of wafer 170. Additionally or instead, Recipe 259 may specify the spacing distances 879 on a lot-by-lot or layer-by-layer basis or on a wafer-by-wafer basis. A lot or layer is a group of wafers processed by the same exposure apparatus under the same nominal conditions. Recipe 259 also allows for the specification of other parameters relating to the spatial images 873a, 873b (such as the dose provided by each image). For example, Recipe 259 may specify the ratio of the number of pulses with the first dominant wavelength 702_1 to the number of pulses with the second dominant wavelength 702_2 in N pulses. These other parameters may also be specified on a field-by-field, lot-by-lot (or layer-by-layer), and / or wafer-by-wafer basis.

[0081]

[0109] Furthermore, recipe 259 may specify that "some layers are not exposed by a first dominant wavelength 702_1 and a second dominant wavelength 702_2, but instead are exposed by a pulse having an optical spectrum that includes a single dominant wavelength." Such an optical spectrum may be used, for example, when a planar semiconductor component is formed instead of a three-dimensional semiconductor component. The I / O interface 253 allows end users and / or manufacturers to program or generate recipes (including, for example, scenarios in which a single dominant wavelength is used for a particular layer or lot) that specify the number of dominant wavelengths.

[0082]

[0110] In addition, while the above example discusses an average optical spectrum 701 having two dominant wavelengths, in other examples, the average optical spectrum 701 may have three or more dominant wavelengths (e.g., three, four, or five) that are separated from other dominant wavelengths by the spectral separation distance and a region such as region 704. The I / O interface 253 allows end users and / or manufacturers to program or generate recipes to specify these parameters.

[0083]

[0111] A three-dimensional (3D) semiconductor component is formed (540). Figure 9A shows a cross-sectional view of an example of a 3D semiconductor component 995. Figure 9B shows the wafer 170 and component 995 in the xy plane at the first surface 878a. The 3D semiconductor component 995 may be a finished component or part of a larger component. The 3D semiconductor component 995 may be any type of semiconductor component that has the feature that it is not entirely formed at one z location within the wafer 170. For example, the 3D semiconductor component may be a device that includes a recess or opening extending along the z axis. The 3D semiconductor component may be used in any type of electronic application. For example, the 3D semiconductor component may be all or part of a 3D NAND flash memory component. 3D NAND flash memory is a memory in which memory cells are stacked along the z axis in layers.

[0084]

[0112] In the example of Figure 9A, the 3D semiconductor component 995 includes a recess 996 formed within the periphery 999. The recess 996 includes a floor 997 and a side wall 998 that generally extends along the z-axis between the periphery 999 and the floor 997. The floor 997 is formed by exposing a photoresist on the surface 878b with light present in the second spatial image 873b (Figure 8A). Features on the periphery 999 are formed using light present in the first spatial image 873a (Figure 8A).

[0085]

[0113] Using process 500 can also produce a sidewall angle 992 that is equal to or closer to 90°, which is possible by other processes. The sidewall angle 992 is the angle between the floor 997 and the sidewall 998. If the sidewall 998 is extended in the xz plane and the floor is extended in the xy plane, then the sidewall angle 992 is 90° and can be considered perpendicular in this example. A sidewall angle closer to perpendicular is desirable because it may allow for better defined features, for example, in a 3D semiconductor component. Process 500 achieves a sidewall angle 992 that is equal to or closer to 90° because the locations of the first spatial image 873a and the second spatial image 873b (the first surface 878a and the second surface 878b, respectively) are separate images located in different parts of the wafer 170. Forming separate spatial images in a single exposure pass allows for improved quality in each image, resulting in more defined features that are more vertically oriented compared to features formed by a lower-quality single spatial image.

[0086]

[0114] Figures 10A and 10B show examples of simulation data related to process 500. Figure 10A shows three plots 1001, 1002, and 1003 of “spatial image intensity” versus “mask position along the y-axis (Figure 9A)”. Each of plots 1001, 1002, and 1003 represents the intensity versus mask position of one spatial image. In Figure 10A, plot 1001 represents a simulation of the average optical spectrum forming two spatial images during a single exposure pass as discussed above with respect to Figure 5. Plot 1002 represents a simulation of a situation where the wafer stage is tilted according to ASML’s EFESE technique (a procedure to increase the depth of focus to facilitate printing of three-dimensional features (such as vias and holes) on the wafer). In the EFESE technique, the wafer stage is tilted at a certain angle to scan the spatial image through the focus while the wafer is exposed. The EFESE technique generally results in a greater depth of focus. In Figure 10A, only plot 1002 represents data simulated by using the EFESE technique. The remaining data shown in Figure 10A did not employ the EFESE technique. Plot 1003 represents data from the best focus simulation based on Dawes.

[0087]

[0115] The spatial image intensity corresponding to the mask position shown in Figure 10A indicates that "forming two or more spatial images in a single exposure pass can produce a contrast similar to that of tilting the wafer stage." Greater contrast indicates a higher probability that 3D features located at various points along the z-axis (Figure 8A) are properly formed.

[0088]

[0116] Figure 10B shows three plots 1004, 1005, and 1006 of the limiting dimensions at the focal positions of three different spatial images, each averaged over the entire exposure pass. In Figure 10B, plot 1004 represents data from a simulation in which a single spatial image was formed without the application of EFESE technology. Plot 1005 represents data from a simulation in which EFESE technology was applied. As shown, the limiting dimension values ​​remain the same with respect to distances further from zero focus, so EFESE technology increases the depth of focus compared to the simulation without EFESE. Plot 1005 represents data from a simulation in which two spatial images were generated in a single exposure pass and EFESE technology was not employed. The depth of focus of the simulation without EFESE using multiple spatial images is equivalent to or better than that of the simulation with EFESE technology. Therefore, process 500 can be used to achieve a greater depth of focus in a single exposure pass without relying on techniques such as EFESE.

[0089]

[0117] Referring to Figure 11A, an implementation form 1150 of the control system 250 is shown as part of the photolithography system 1100. The control system 1150 includes a processor 251, electronic storage 252, and an I / O interface 253, which are configured to connect to a spectral feature selection module 258 in the light source 1105, thereby enabling adjustment of the spectral features of the pulsed light beam 1160 output from the light source 1105. In addition, the control system 1150 includes an energy control module 1161E configured to provide the light source 1105 with excitation signals 1168E used to control electrodes in the master oscillator of the light source 1105 (such as the master oscillator 212 in Figure 2A). The energy control module 1161E may also be configured to provide excitation signals to one or more other oscillators in the light source 1105. The control system 1150 can be used with any type of light source 1105. The control system 1150 can be used with a light source 1105 that includes a single-optical oscillator. The control system 1150 may be used with a multi-stage light source (e.g., light source 205 in Figure 2A) 1105 which includes one or more optical oscillators and one or more power amplifiers.

[0090]

[0118] The light source 1105 provides a pulsed light beam 1160 to the lithography exposure apparatus 1169. The energy control device 1160E is formed from an energy control module 1161E and a photodetector system 1145E. The photodetector system 1145E is configured to sense light (such as the pulsed light beam 1160) and generate an energy characteristic signal 1146E. The photodetector system 1145E is any type of photosensor or detector capable of measuring the light energy in the pulsed light beam 1160 and generating an energy characteristic signal 1146E based on this measurement. The energy characteristic signal 1146E contains information about the energy in one or more pulses of the light beam 1160. The energy characteristic may be, for example, the light energy of the light pulses in the pulsed light beam 1160 or the energy error associated with the light pulses in the pulsed light beam 1160.

[0091]

[0119] An energy control module 1161E, configured to amplify a signal and apply a voltage to one or more electrodes 217 (shown in Figure 2A), generates an excitation signal 1168E, or causes the excitation signal 1168E to be generated by a separate device such as a power supply 1197E. When the excitation signal 1168E is applied to one or more optical oscillators in the light source 1105, the optical oscillators generate optical pulses. The excitation signal 1168E and the pulses in the optical beam 1160 are time-varying signals. In the following discussion, individual instances of the excitation signal 1168E, pulses, and energy characteristic signal 1146E may be indexed by k, where k is an integer. For example, the k-th instance of the excitation signal 1168E (excitation signal 1168E(k)) generates pulse k in the optical beam 1160. The energy control module 1161E receives an instance of the energy characteristic signal 1146E and generates an instance 1168E of the excitation signal for each pulse in the light beam 1160.

[0092]

[0120] The amount of light energy generated in response to the application of the excitation signal 1168E (i.e., the energy in the pulse of the light beam 1160) depends on the characteristics of the excitation signal 1168E. For example, the excitation signal 1168E may be a series of voltage pulses, and the characteristics of the excitation signal 1168E may include the amplitude and / or temporal duration of the voltage pulses. The energy control module 1161E determines the excitation signal 1168E or the characteristics of the excitation signal 1168E. In the following discussion, the energy control module 1161E and its various implementations are described as generating or determining the excitation signal 1168E. However, in some implementations, the energy control module 1161E (or any of its various implementations) generates the characteristics of the signal 1168E that is supplied to the power supply 1197E, and the power supply 1197E generates the signal 1168E based on these characteristics. For example, the excitation signal 1168E may be a high-voltage signal generated by the power supply 1197E.

[0093]

[0121] The energy control module 1161E is implemented to enable spectral feature-dependent (e.g., wavelength-dependent) dose or energy control in the lithography exposure apparatus 1169. Specifically, the energy control module 1161E allows the dose and / or energy of the current pulse in the light beam 1160 to be changed relative to the previous adjacent pulse in the light beam 1160. This change may be made pulse by pulse in the light beam 1160 such that the energy changes with each pulse of the light beam 1160. By changing and modifying the excitation signal 1168E provided to the light source 1105, the energy control module 1161E is configured to provide pulse-by-pulse control of the dose and / or energy of pulses in the light beam 1160.

[0094]

[0122] It may be desirable to generate various energies for various pulses in a manner that depends on the wavelength selected for the pulse. In this way, it may be desirable that the dose and / or energy values ​​of the pulses depend on the pulse wavelength (or other spectral features or simply the number of pulses or pulse duration). For example, referring to Figure 7, it may be desirable to generate a first set of pulses with a first dominant wavelength 702_1 at a first target energy Etarget1, and a second set of pulses with a second dominant wavelength 702_2 at a second target energy Etarget2, which is different from the first target energy Etarget1. In this way, the dose and / or energy of the pulses of the optical beam 1160 can be optimized for each spatial image 873a, 873b in the field.

[0095]

[0123] As discussed above with reference to Figure 2A-2C, the light source 1105 includes a spectral feature selection module 258 coupled to the light propagating within the light source 1105 to allow fine tuning of spectral features such as wavelength and bandwidth within the master oscillator 212. In multifocus imaging, the spectral feature selection module 258 can change its configuration with each pulse or with any nth pulse, where n is an integer greater than 1. Each optical oscillator 212 is associated with a specific configuration of the spectral feature selection module 258 and with a number of transfer functions relating to the efficiency characteristics of that configuration. The specific transfer function relates the characteristics of the excitation signal 1168E while within that specific configuration to the amount of optical output (in the pulsed light beam 224 or 260) generated by the optical oscillator 212. As a specific example referring to Figure 2A, the transfer function of a specific configuration of the optical oscillator 212 (and a specific configuration of the spectral feature selection module 258) relates the amount of voltage applied to the electrode 217 in the discharge chamber 214 to the optical energy generated by the gain medium in the discharge chamber 214.

[0096]

[0124] Referring to Figure 11B, the transfer function TF (the optical energy generated by the single optical oscillator 212 depending on the excitation energy provided) varies with the wavelength of the emitted pulsed light beam. Figure 11B includes the transfer function TF(1), which is the efficiency of the optical oscillator 212 when the pulse center or dominant wavelength is a first wavelength (λp1), and the transfer function TF(2), which is the efficiency of the optical oscillator 212 when the pulse center or dominant wavelength is a second wavelength (λp2). The transfer functions TF(1) and TF(2) relate the voltage V applied to the excitation mechanism of the optical oscillator 212 to the pulsed optical energy of the light beam 1160 generated by the optical oscillator 212. Both the transfer functions TF(1) and TF(2) are locally nearly linear but have different slopes and different y-intercepts. The pulse energy (Epulse) depends on the transfer function TF as follows: Epulse = TF[HVSetPoint - OffsetV] + OffsetE + Noise, where HVSetPoint is the discharge voltage setpoint, OffsetV is the voltage offset applied to the excitation mechanism of the optical oscillator 212, and OffsetE is the energy offset.

[0097]

[0125] In one example, the optical oscillator 212 alternately generates optical pulses at a first dominant wavelength (λp1) and optical pulses at a second dominant wavelength (λp2) to produce a pulsed optical beam 1160 having spectral peaks at a first dominant wavelength and spectral peaks at a second dominant wavelength. In this way, the optical pulse at the first dominant wavelength (λp1) is usually mixed with the optical pulse at the second dominant wavelength (λp2) (interleaved in some implementations).

[0098]

[0126] System 1160 attempts to maintain a first target energy Etarget1 for an optical pulse at a first dominant wavelength (λp1) and a second target energy Etarget2 for an optical pulse at a second dominant wavelength (λp2). For example, the k-th pulse has dominant wavelengths of energy E1 and λp2. After the k-th pulse is generated, the optical elements in the spectral feature selection module 258 are operated so that the dominant wavelength of the k+1th pulse is λp2. Thus, System 1160 is configured to generate a pulse whose dominant wavelength is the second dominant wavelength (λp2) and determines the voltage to apply to the optical oscillator 212 to generate the k+1th pulse based on an estimation of the transfer function TF(2), which is an accurate representation of the efficiency of the optical oscillator 212 configuration.

[0099]

[0127] The energy control module 1161E may be configured to determine the excitation signal 1168E based on a transfer function associated with a specific configuration of the spectral feature selection module 258 used to generate the subsequent optical pulse. For example, the spectral feature selection module 258 includes at least one prism, and each transfer function may be associated with a different position on at least one prism.

[0100]

[0128] Each time the energy of the current pulse changes relative to the previous adjacent pulse, an energy disturbance occurs due to the difference in transfer functions and their imperfect estimations associated with each state of the spectral feature selection module 258 of the light source 1105. Furthermore, undesirable oscillations in the energy of the pulses of the light beam 1160 may occur due to the coupling of the pulse energy and wavelength of the light beam 1160. Without any kind of correction mechanism to quickly correct these energy disturbances, the dose and / or energy of the pulses of the light beam 1160 may be erroneous or suboptimal, which further introduces errors in the wafer 170. The energy control module 1161E corrects or modifies the excitation signal 1168E by using a correction module and a modeling module that estimates the transfer functions of each state of the spectral feature selection module 258, so that the energy control module 1161E can eliminate or reduce energy disturbances. Furthermore, the energy control module 1161E performs this control on a pulse-by-pulse basis to correct errors occurring with each pulse.

[0101]

[0129] Referring to Figure 12, an implementation configuration of the energy control module 1161E used with the optical oscillator 1212E is shown. The energy control module 1261E is configured to be implemented as part of a control system 1150 or 250. The optical oscillator 1212E may be one of two or more optical oscillators in a multistage light source (such as the light source 205 in Figure 2A). The output of the optical oscillator 1212E is a pulsed light beam, such as the seed light beam 224 or the output light beam 260 (Figure 2A). In some implementation configurations, it is possible to have separate energy control modules 1261E configured for each optical oscillator in the multistage light source. For example, the first energy control module 1261E may be configured for the master oscillator 212, while the second energy control module 1261E may be configured for the power amplifier 230 (see Figure 2A). In other implementations, the single energy control module 1261E can be configured for both the master oscillator 212 and the power amplifier 230 (see Figure 2A).

[0102]

[0130] The energy control module 1261E includes a comparator 1263E and an energy controller 1262E. The energy control module 1261E also includes a target energy generator 1270E. The comparator 1263E receives an energy characteristic signal 1246E from the photodetector system 1145E and also receives the target energy Etarget 1271E from the target energy generator 1270E. The comparator 1263E performs comparison functions, such as subtraction, to determine the error signal 1266E. The energy controller 1262E includes one or more modules configured to determine the excitation signal 1268E corresponding to the excitation signal 1168E referenced in Figure 11A. The excitation signal 1268E takes into account the error signal 1266E and also takes into account variations in the transfer function of the optical oscillator 1212E, as discussed below.

[0103]

[0131] Referring to Figure 13, a more detailed diagram of the master oscillator 212 is shown. Two elongated electrodes 217 include a cathode 217-a and an anode 217-b contained within the discharge chamber 214. The potential difference between cathode 217-a and anode 217-b forms an electric field within the gas gain medium 219. This potential difference is generated by controlling the power supply 1197E to apply a voltage to cathode 217-a and / or anode 217-b. In this example, the power supply 1197E is controlled by an excitation signal 1168E. The excitation signal 1168E contains enough information to cause the power supply 1197E to generate a voltage signal 1168Ev and to apply the voltage signal 1168Ev to the master oscillator 212 according to the trigger signal 330 (Figure 3C). The voltage signal 1168Ev has an amplitude defined by the excitation signal 1168E. The power supply 1197E applies a voltage signal 1168Ev to the gain medium 219, thereby applying a voltage of a specific amplitude to the cathode 217-a and / or anode 217-b, so that the electric field provides sufficient energy to cause population inversion and sufficient energy to enable the generation of pulses of the light beam 224 through stimulated emission. The repeated generation of such potential differences forms a series of pulses that are emitted as the light beam 224 and therefore the light beam 260 (Figure 2A).

[0104]

[0132] Referring again to Figure 12, comparator 1263E performs comparison functions such as subtraction. Comparator 1263E receives the energy characteristic signal 1246E from the photodetector system 1145E and the value of the target energy Etarget 1271E from the target energy generator 1270E. The energy characteristic signal 1246E contains an index of the amount of light energy in pulse k-1, which is the pulse immediately preceding pulse k.

[0105]

[0133] The target energy Etarget 1271E is the target or desired optical energy value for a subset of optical pulses in the optical beam 1160. The target energy Etarget 1271E is a predetermined optical energy associated with the acceptable or optimal performance of the photolithography system 1100. The value of Etarget 1271E may be stored in electronic storage 252 within the light source 1105 or elsewhere, and may be available to the comparator 1263E when needed. In some implementations, the value of Etarget 1271E may be commanded by the lithography exposure apparatus 1169 (as indicated by arrow 1165). As discussed above, the energy control module 1161E is implemented to enable spectral feature-dependent dose or energy control in the lithography exposure apparatus 1169. To perform wavelength-dependent dose or energy control, the target energy generator 1270E provides or determines a target energy Etarget 1271E associated with the spectral characteristics (such as the dominant wavelength λp) of the pulse of the optical beam 1160 generated by the optical oscillator 1212E.

[0106]

[0134] For example, Figure 14 shows a table correlating each target energy Etarget 1271E_i with each possible dominant wavelength λp 1402_i of a set of pulses of the light beam 1160, where i is an integer greater than 1 and has a maximum value M. This table may be stored in the light source 1105 or the lithography exposure apparatus 1169 and can be accessed by the target energy generator 1270E when pulses of the light beam 1160 are generated.

[0107]

[0135] As another example, Figure 15A shows a graph of target energy Etarget 1571E for four dominant wavelengths 1502, each associated with a set of optical beam pulses. Thus, dominant wavelength 1502a is associated with target energy Etarget 1571Ea; dominant wavelength 1502b is associated with target energy Etarget 1571Eb; dominant wavelength 1502c is associated with target energy Etarget 1571Ec; and dominant wavelength 1502d is associated with target energy Etarget 1571Ed. In this example, as shown in Figure 15B, four distinct spatial images 1573a, 1573b, 1573c, and 1573d are formed on wafer 170 during the same exposure pass, with each spatial image 1573a, 1573b, 1573c, and 1573d being formed on their respective distinct planes 1578a, 1578b, 1578c, and 1578d along the z-axis. The location of the plane depends on the dominant wavelength 1502. Therefore, for example, the spatial image 1573a is formed on plane 1578a, and its location along the z-axis depends on the dominant wavelength 1502a. Thus, each spatial image 1573a, 1573b, 1573c, and 1573d is associated with its respective distinct energies 1571Ea, 1571Eb, 1571Ec, and 1571Ed. In Figure 15B, each distinct energy 1571Ea, 1571Eb, 1571Ec, and 1571Ed are represented by different levels of shading within their respective spatial images 1573a, 1573b, 1573c, and 1573d.

[0108]

[0136] Referring again to Figure 12, in order to determine the target energy Etarget 1271E associated with the dominant wavelength of pulse k-1 of the light beam 1160, the target energy generator 1270E may access information or data regarding the dominant wavelength of pulse k-1 from the light source 1105. For example, if the energy characteristic signal 1246E is associated with pulse k-1, the target energy generator 1270E may output the target energy Etarget 1271E associated with the dominant wavelength of pulse k-1. As another example, the target energy generator 1270E may output the target energy Etarget 1271E based on the number of pulses or an index. For example, referring to Figures 15A and 15B, if pulse k-1 has a dominant wavelength 1502c (corresponding to a set of pulses represented by c), the target energy generator 1270E may determine that the target energy Etarget 1271E of pulse k-1 is 1571Ec. On the other hand, if pulse k-1 has a dominant wavelength of 1502a (corresponding to a set of pulses represented by a), the target energy generator 1270E determines that the target energy Etarget 1271E of pulse k-1 is 1571Ea.

[0109]

[0137] Furthermore, the value of Etarget 1271E and / or the index of the amount of light energy in the energy characteristic signal 1246E can be processed before being received by comparator 1246E. For example, if the value of Etarget 1271E is in units of energy (joules) and the index of the amount of light energy in the energy characteristic signal 1246E is in units of power (watts), the index can be converted to units of energy (joules) before being received by comparator 1263E. Comparator 1263E determines the energy error 1266E associated with pulse k-1 of the light beam 1160, and the energy error 1266E corresponds to the difference between the amount of energy in pulse k-1 and Etarget 1271E.

[0110]

[0138] The energy error 1266E is provided to the energy controller 1272E to determine the excitation signal 1268E. The characteristics of the excitation signal 1268E are based on the energy error 1266E (which in turn is based on an indicator of the amount of energy in the energy characteristic signal 1246E). Furthermore, the energy controller 1272E corrects the excitation signal 1268E to compensate for variations in the transfer function of the optical oscillator 1212E. The transfer function varies because the spectral characteristics (wavelengths) of pulses in the optical beam 1160 are not necessarily the same. For example, the center or dominant wavelength of each pulse may vary on a per-pulse basis by changing the configuration of the spectral feature selection module 258 before generating the pulse. The dominant wavelength may alternate between several values ​​to form a pulsed optical beam 1160 with spectral peaks at each dominant wavelength, where any two peaks are separated from each other by the spectral distance, which is the difference between the dominant wavelengths of the two peaks. There is little to no light in the pulsed optical beam at wavelengths between two adjacent dominant wavelengths.

[0111]

[0139] The corrected excitation signal 1268E is applied to the optical oscillator 1212E to compensate for variations in the efficiency of the optical oscillator 1212E. By correcting the excitation signal 1268E, the energy control module 1261E ensures that the energy of a pulse of a specific dominant wavelength in the pulsed light beam 1160 falls within the acceptable range of the target energy 1271E associated with that specific dominant wavelength.

[0112]

[0140] Referring to Figure 16, the energy control module 1161E in implementation configuration 1661E is shown for use with the optical oscillator 1212E. In this implementation configuration, the energy control module 1661E includes multiple energy controllers 1672E (one for each dominant wavelength λp). In this implementation configuration, two energy controllers 1672E_1 and 1672E_2 (one for each of the two dominant wavelengths) are shown so that the optical oscillator 1212E generates a pulse having a first dominant wavelength λp1 at a first target energy 1671E_1 and a pulse having a second dominant wavelength λp2 at a second target energy 1671E_2. In other implementation configurations, the energy control module 1661E may include three or more energy controllers 1672E (the same number of energy controllers 1672E as the number of dominant wavelengths in the optical beam 1160). Each of the energy controllers 1672E may be of any preferred design or operation. Furthermore, any one energy controller 1672E within the energy control module 1661E may have a different design or operation from the other energy controllers 1672E within the energy control module 1661E.

[0113]

[0141] The energy control module 1661E includes a pair of comparators 1663E (one for each energy controller 1672E). In the shown implementation, the first comparator 1663E_1 is associated with the first energy controller 1672E_1, and the second comparator 1663E_2 is associated with the second energy controller 1672E_2. The energy control module 1661E also includes a target energy generator 1670E that generates a target energy Etarget for each dominant wavelength λp. Accordingly, in this embodiment, the target energy generator 1670E generates a first target energy Etarget 1671E_1 at a first main wavelength λp1, which is provided to the first comparator 1663E_1, and then generates a second target energy Etarget 1671E_2 at a second main wavelength λp2, which is provided to the second comparator 1663E_1.

[0114]

[0142] The energy control module 1661E includes switches 1646Es configured to determine where to transmit the energy characteristic signal 1646E. Specifically, switches 1646Es provide the energy characteristic signal 1646E to a first comparator 1663E_1 if the current pulse has a first dominant wavelength λp1, and provide the energy characteristic signal 1646E to a second comparator 1663E_2 if the current pulse has a second dominant wavelength λp2. In other implementations, instead of the switches in the photodetector system 1145E, each switch may be implemented in comparators 1663E_1 and 1663E_2.

[0115]

[0143] Energy controllers (such as energy controller 1272E configured to operate for all major wavelengths λp, or energy controllers 1672E_1, 1672E_2, each configured to operate for a single major wavelength λp) can have any preferred design or operation. Several preferred implementations of energy controllers are then discussed with reference to Figures 17–20. Any one of these energy controllers can be implemented as any one of energy controllers 1272E, 1672E_1, or 1672E_2. Furthermore, it is possible to combine the operation of multiple energy controllers into a single operation of energy controllers 1272E, 1672E_1, or 1672E_2.

[0116]

[0144] Referring to Figure 17, the energy controller implementation 1772E uses a notch filter. The energy controller 1772E includes a delay module 1767E, an excitation decision module 1762E, and a correction module 1764E. The delay module 1767E receives the energy error 1766E from comparator 1763E, which can be any one of comparators 1263E, 1663E_1, or 1663E_2. The delay module 1767E introduces a time delay into the energy error 1766E to ensure proper causality so that the action taken by the energy controller 1772E, which receives the measurement result (from the energy characteristic signal 1246E), is not applied to the pulse. Although the delay module 1767E is shown as a separate block, its function may be implemented within the photodetector system 1145E or the excitation decision module 1762E.

[0117]

[0145] The energy error 1766E is provided to the excitation decision module 1762E, which determines the excitation signal 1768Ep. The characteristics of the excitation signal 1768Ep are based on the energy error 1766E, and by extension, on the energy quantity indicators in the energy characteristic signals 1246E and 1646E. Thus, for example, the excitation decision module 1762E can determine how much the voltage to the electrodes of oscillator 1212E should be adjusted to compensate for the energy error of the light beam output from oscillator 1212E.

[0118]

[0146] The excitation signal 1768Ep is provided to the correction module 1764E. The correction module 1764E determines the corrected excitation signal 1768E based on the excitation signal 1768Ep. Specifically, the correction module 1764E corrects the excitation signal 1768Ep to compensate for variations in the transfer function of the optical oscillator 1212E. The transfer function varies because the spectral characteristics of pulses in the optical beam 1160 are intentionally not necessarily the same. For example, the center or dominant wavelength λp of each pulse may change on a per-pulse basis by changing the configuration of the spectral feature selection module 258 before generating the pulse. The dominant wavelength may alternate between multiple values ​​to form a pulsed optical beam 1160 having spectral peaks at each dominant wavelength, where any two peaks are separated from each other by a spectral distance, which is the difference between the dominant wavelengths of the two peaks. There is little to no light in the pulsed optical beam at wavelengths between two adjacent dominant wavelengths.

[0119]

[0147] The correction module 1764E implements a filter (such as a notch filter) that determines the corrected excitation signal 1768E based on at least the transfer function TF(k) of the optical oscillator 1212E when generating the k-th pulse, the energy error 1766E of the k-th pulse, the cumulative energy error of the k-th pulse, one or more values ​​of the preceding excitation signal of a pulse having the same dominant wavelength as the k-th pulse, and one or more tuning parameters or gains related to energy and / or dose error. Generally, a notch filter rejects signals with frequencies within the frequency band and transmits signals with frequencies outside the frequency band. The notch filter is configured to reject energy disturbances that may arise from using optical pulses from various configurations (various transfer functions) of the optical oscillator 1212E. The notch filter can be expressed by the following equation:

number

Equation

[0120]

[0148] The correction excitation signal 1768E is applied to the optical oscillator 1212E to correct the variation in the efficiency of the optical oscillator 1212E. By correcting the excitation signal 1268E, the energy control module 1261E causes the energy of the pulses of a specific main wavelength within the pulsed optical beam 1160 to fall within the allowable range of the target energy (Etarget 1271E or Etarget 1671E_1, Etarget 1671E_2, etc.) associated with the specific main wavelength.

[0121]

[0149] Referring to Figure 18, the energy controller implementation 1872E uses a Kalman filter with linear quadratic estimation. The energy controller 1872E includes a delay module 1867E that receives an error signal from comparator 1863E, which may be any one of comparators 1263E, 1663E_1, or 1663E_2. As discussed above, the delay module 1767E introduces a time delay to the energy error 1866E to ensure proper causality so that the action taken by the energy controller 1872E, which receives the measurement result (from the energy characteristic signal 1246E), is not applied to the pulse. Although the delay module 1867E is shown as a separate block, its function may be implemented within the photodetector system 1145E or another component of the energy controller 1872E. The energy controller 1872E includes an excitation decision module 1862E, a correction module 1864E, and a second comparator 1869E.

[0122]

[0150] Similar to the excitation decision module 1762E, the excitation decision module 1862E determines the excitation signal 1868Ep based on the energy error 1866E output from the delay module 1867E. In particular, the excitation decision module 1862E includes a set of transfer function models, each associated with one of the states of the optical oscillator 1212E. Specifically, each transfer function TF of the optical oscillator 1212E is associated with a particular configuration of the spectral feature selection module 258 that generates a separate dominant wavelength λp, and each transfer function TF is related to the efficiency characteristics of that configuration. To calculate the excitation signal 1868Ep, the excitation decision module 1862E selects a model M(TF) associated with the transfer function TF of the optical oscillator 1212E that generated the k-th pulse. In formulaic form, this can be expressed by the following equation:

number

[0123]

[0151] The correction module 1864E is implemented as a Kalman filter that efficiently rejects pulse-by-pulse energy disturbances with a known period. The Kalman filter 1864E uses the energy error 1866E from comparator 1863E and the excitation signal 1868Ep from excitation decision module 1862E to determine the output signal 1864Eo. The output signal 1864Eo is supplied to a second comparator 1869E. The second comparator 1869E determines the corrected excitation signal 1868E based on the output signal 1864Eo and the excitation signal 1868Ep.

[0124]

[0152] The output signal 1864Eo of the Kalman filter 1864E is based on a coefficient directly related to the energy error 1866E of the k-th pulse, a model M(TF) associated with the period during which the configuration of the spectral feature selection module 258 changes, and the excitation signal 1868E applied to generate the k-th pulse. The output signal 1864Eo of the Kalman filter 1864E also takes into account the gain and tuning parameters of the Kalman filter 1864E.

[0125]

[0153] The output signal 1864Eo of the Kalman filter can be expressed according to the following equation: KXpred(k+1)=A*KXpost(k) Equation (5) Here, A=1, and KXpost(k) is an estimator of the output of the Kalman filter 1864E for the k-th pulse, given by the following equation: KXpost(k)=KXpred(k)+K_K(k)*Ke(k) Equation (6) Here, K_K is the gain of the Kalman filter 1864E, and is given by the following equation:

number

number

[0126]

[0154] K_S(k) is given by K_S(k) = KPpred(k) + R, where R is a tuning parameter. KPpred(k) is the covariance of KXpred(k). KPpred(k) can also be considered a confidence level for determining the gain K_K of the Kalman filter 1864E. Therefore, if KPpred(k) is 0, then K_K = 0, which means we are very confident in the model prediction and will not need the output from the photodetector system 1145E. On the other hand, if KPpred(k) is very large compared to the noise R in the photodetector system 1145E, then K_K = 1, which means we can only trust the photodetector system 1145E. KPpred(k+1) is given by: KPpred(k+1)=A*KPpost(k)*A+Q Equation (9) Here, A=1, Q is the tuning parameter of the Kalman filter 1864E, and KPpost(k) is given by the following equation: KPpost(k)=(1-K_K(k))*KPpred(k)*(1-K_K(k)*C')+K_K(k)*R*K_K(k)' Equation (10) Here, C is the tuning parameter of the Kalman filter 1864E, which can be equal to 1 in this implementation, and R is the tuning parameter.

[0127]

[0155] The second comparator 1869E determines the corrected excitation signal 1868E as follows: HVSP(k)=HVCommand(k)+HVDefault-KXpred(k) Equation (11) Here, HVSP(k) is the corrected excitation signal 1868E, HVCommand(k) is the uncorrelated excitation signal 1868Ep determined by the excitation decision module 1862E for the k-th pulse, HVDefault is a parameter that estimates the nominal excitation signal of the transfer function TF of the optical oscillator 1212E for the k-th pulse, and KXpred(k) is the output signal 1864Eo of the Kalman filter 1864E for the k-th pulse. The value of HVDefault is stored in electronic storage and can be retrieved when needed by the energy controller 1872E. The value of HVDefault can be a voltage magnitude and can be, for example, greater than 100 volts.

[0128]

[0156] Referring to Figure 19A, the implementation of the energy control module 1161E uses a feedforward technique to reject or reduce pulse-per-pulse energy disturbances or energy fluctuations that occur as a result of intentionally changing the configuration of the spectral feature selection module 258 associated with the optical oscillator 1212E in order to vary the spectral characteristics of the optical beam 1160 generated by the optical oscillator 1212E. The energy control module 1961E relies on a set of estimated EvsV(λp), each of which is an estimate of the relationship between the input to the optical oscillator 1212E (excitation signal or V) and the output from the optical oscillator 1212E (energy E of the optical beam 1160) for each major wavelength λp. The energy control module 1961E includes a target energy generator 1970E (operating similarly to the target energy generator 1270E), a comparator 1963E, and an energy controller 1972E.

[0129]

[0157] Referring to Figures 19B and 19C, the details of the energy controller 1972E are shown. The energy controller 1972E includes a delay module 1967E and an excitation decision module 1962E. The output of the delay module 1967E is the energy error 1966E output from the comparator 1963E, and the energy error 1966E corresponds to a measure of the difference between the energy characteristic signal 1946E (which is the energy in the previous pulse: see Figure 19A) and the energy target 1971E. The excitation decision module 1962E determines the corrected excitation signal 1968E and provides the corrected excitation signal 1968E to the optical oscillator 1212E.

[0130]

[0158] Figure 19C is a block diagram of the excitation decision module 1962E. The excitation decision module 1962E may include a feedback controller FC. In some implementations, the feedback controller FC is a proportional-integral-derivative (PID) controller that receives an error signal 1966E and generates an output that is applied downstream to one of the selected transfer functions (as will be discussed below). For example, a PID controller includes proportional, integral, and derivative terms. Although a PID controller is discussed, any feedback controller can be used as the feedback controller FC.

[0131]

[0159] The excitation decision module 1962E includes a transfer function selector 1974E that selects one transfer function TF(1), TF(2), ... TF(N). Each of the transfer functions TF(1), TF(2), ... TF(N) is an estimated transfer function of the optical oscillator 1212E at a specific dominant wavelength λp and is associated with a specific configuration of the spectral feature selection module 258 (Figure 13). The spectral feature selection module 258 has N different configurations, each associated with a different spectral parameter (e.g., bandwidth center or dominant wavelength) of the output optical beam 1160. N is greater than 1 and indexes all possible configurations of the spectral feature selection module 258 relevant to a particular application. Each of the N configurations of the spectral feature selection module 258 is associated with each of the transfer functions TF(1), TF(2), ... TF(N) of the optical oscillator 1212E. For example, an index value of N associated with a specific one of the transfer functions TF(1), TF(2), ... TF(N) may be stored in a lookup table or database along with data defining the transfer function TF and the center or dominant wavelength λp generated by that configuration of the spectral feature selection module 258. The transfer functions TF(1), TF(2), ... TF(N) may be stored on electronic storage 252 and may be accessible from the energy control module 1961E. The transfer functions TF(1), TF(2), ... TF(N) may be associated with N configurations by the manufacturer, or provided by the operator of system 1100, or may be estimated and updated online using the history of input (discharge voltage) and output (measured energy).

[0132]

[0160] The transfer function selector 1974E determines which of the transfer functions TF(1), TF(2), ... TF(N) is associated with the configuration that generates the k-th pulse of the output light beam 1160 emitted from the optical oscillator 1212E. The transfer function selector 1974E can select from the transfer functions TF(1), TF(2), ... TF(N) by performing a remainder function that returns the remainder of a division operation in which k is divided by M, where M is an integer representing the number of N configurations (alternating or cyclical to generate light pulses) of the spectral feature selection module 258, and k indexes the number of pulses. Thus, M is 2, N, or any number greater than 2 and less than or equal to N. If the transfer function selector 1974E is performed as a remainder function and M=2, the transfer function selector 1974E returns 0 for pulses with an even k index and 1 for pulses with an odd k index. In these implementations, if the transfer function selector 1974E returns 0, the transfer function TF(1) is selected, and if the transfer function selector 1974E returns 1, the transfer function TF(2) is selected.

[0133]

[0161] In another example, the center or dominant wavelength λp of the optical pulses generated by the optical oscillator 1212E varies from pulse to pulse according to a predetermined recipe. For example, the optical oscillator 1212E and the spectral feature selection module 258 can be controlled so that the dominant wavelength λp cycles in a continuous manner between four predetermined dominant wavelengths (such as those shown in Figures 15A and 15B). Thus, the transfer function selector 1974E selects the transfer function TF(2) for the second and sixth pulses, the transfer function TF(3) for the third and seventh pulses, and so on.

[0134]

[0162] The error signal 1966E is supplied to the selected transfer function TF (via the transfer function selector 1974E), and the output of the selected transfer function TF is supplied to the gain 1984E, and then to the integrator 1985E. The feedforward correction signal 1967E is supplied to the integrator 1985E and is based on the EvsV curve selected based on the dominant wavelength of the next pulse of the optical beam 1160. The feedforward correction signal 1967E removes, reduces, or rejects energy disturbances. Signal 1967E corrects the energy difference caused by changing the configuration of the spectral feature selection module 258 and changing the Etarget during the operation of the optical oscillator 1212E, and determines the correction excitation signal 1968E. The correction excitation signal 1968E(V(k+1)) is determined based on the following equation:

number

[0135]

[0163] Referring to Figure 20, the implementation of the energy control module 1161E uses an energy feedforward-dependent iterative control technique to invert or cancel out arbitrary iterative disturbances (appearing as patterns in the energy characteristic signal 2046E), which arise from intentionally changing the configuration of the spectral feature selection module 258 associated with the optical oscillator 1212E in order to vary the spectral characteristics of the optical beam 1160 generated by the optical oscillator 1212E. The energy control module 2061E includes a target energy generator 2070E (operating similarly to the target energy generator 1270E), a comparator 2063E, and an energy controller 2072E.

[0136]

[0164] To invert or cancel out any recurring disturbance, the energy controller 2072E requires deductive knowledge of the characteristics of any recurring disturbance to model the disturbance and modify the excitation signal 2068E in bulk (for a set number of future pulses). The energy controller 2072E may include a deduction module 2072ED configured to acquire this deductive knowledge, for example by measuring the disturbance on each burst of a pulse, and then use this information to develop a model of the disturbance. The energy controller 2072E may also include a correction module 2072EC configured to modify the excitation signal 2068E based on the disturbance model.

[0137]

[0165] The energy controller 2072E relies heavily on the direct observation of these disturbances; therefore, it is important to incorporate deductive knowledge about the disturbances (including how the disturbances fluctuate or change). For example, it is known that the disturbances fluctuate significantly with the pulse repetition rate of the light beam 1160, and it may be useful to ensure that the deductive module compensates for this dependency.

[0138]

[0166] In some implementations, the deduction module 2072ED within the energy controller 2072E may acquire an energy characteristic signal 2046E for a certain period (e.g., a set number of pulses within a burst (called a disturbance period) of the light beam 1160). The deduction module 2072ED may then compare each of these energy characteristic signals 2046E with the target energy Etarget 2071E, thereby generating the energy error (part of the energy signal 2066E) for each pulse within the disturbance period. The deduction module 2072ED may calculate "how much of this energy error can be estimated to have been removed by other feedback controllers within the energy controller 2072E," and this is added to the measured energy error to obtain the total error. Other feedback controllers may include the controllers discussed herein. What remains is the amount of energy error that the other feedback controllers did not or could not remove, and therefore which the energy deduction module 2072ED removes. For each pulse during the disturbance period, the deduction module 2072ED updates the magnitude and, or alternatively, the sign of the disturbance, and the energy error passes through an integrator (within the deduction module 2072ED) with a gain of less than 1 to produce an inverted disturbance shape. Each pulse during the disturbance period is processed independently; therefore, it is assumed that there is no correlation between pulses. In the next disturbance period, the correction module 2072EC adds the latest disturbance shape to the excitation signal 2068E. This technique is repeated throughout each disturbance period, resulting in training of the feed-forward control.

[0139]

[0167] Referring to Figure 21, procedure 2100 is performed by the photolithography system 1100. Procedure 2100 determines a correction input signal (excitation signal 1168E) for application to the light source 1105 and, in particular, to the optical oscillator 1212E. Procedure 2100 is performed at least in part by the control system 1150, which includes the energy control module 1161E. The control system 1150 and / or some part of the control system 1150 (such as the energy control module 1161E) may be implemented as part of the light source 1105, as part of the lithography exposure apparatus 1169, or separately from (but in communication with both) the light source 1105 and / or the lithography exposure apparatus 1169.

[0140]

[0168] Multiple sets of pulses of the light beam 1160 are generated (2105). In particular, the light source 1105 generates the light beam 1160 such that each pulse in the light beam 1160 is associated with a distinct dominant wavelength λp and possibly a distinct target energy Etarget. The distinct dominant wavelength λp is determined based on the configuration of the spectral feature selection module 258.

[0141]

[0169] Next, the measurement result of the energy of the preceding pulse of the light beam 1160 is received (2110). For example, the control system 1150 (and in particular the energy control module 1161E) receives the energy characteristic signal 1146E of the k-th pulse (which may be considered the preceding pulse) from the detection system 1145E.

[0142]

[0170] The energy error of the preceding pulse is determined (2115). For example, referring to Figure 12, the error signal 1266E is output from comparator 1263E, or referring to Figure 16, the error signal 1666E_1 is output from comparator 1663E_1. If the k-th pulse has a dominant wavelength λp2, the comparator (1263E or 1663E_2, etc.) compares the measured energy (determined from the energy characteristic signal 1146E) of the preceding optical beam pulse with the second target energy Etarget2, since the second target energy Etarget2 is associated with the second set of pulses. On the other hand, if the k-th pulse has a dominant wavelength λp1, the comparator (1263E or 1663E_1, etc.) compares the measured energy (determined from the energy characteristic signal 1146E) of the preceding optical beam pulse with the first target energy Etarget1, since the first target energy Etarget1 is associated with the first set of pulses.

[0143]

[0171] At least one component of the light source 1105 is tuned to adjust the energy of subsequent pulses of the light beam 1160 based on the determined error (2115) (2120). The tuned subsequent pulse has a dominant wavelength that is the same as the dominant wavelength of the preceding pulse. Thus, for example, the spectral feature selection module 258 is configured to alternately generate pulses having a first dominant wavelength λp1 and pulses having a second dominant wavelength λp2 (as shown in Figures 7 and 8A), and if the preceding pulse (k-th pulse) has a first dominant wavelength λp1, then the k+2x pulse (where x is a positive integer) is tuned because the k+2x pulse also has a first dominant wavelength λp1.

[0144]

[0172] In particular, the corrective excitation signal 1168E is applied to the optical oscillator 1212E. For example, the voltages to electrodes 217-a and 217-b are adjusted based on this corrective excitation signal 1168E.

[0145]

[0173] Embodiments can be further described by using the following clauses: 1. In a method for controlling the energy of a pulsed light beam, this method is: The process of generating multiple mixed sets of pulses of light beams from a light source, wherein each set of light beam pulses is associated with a distinct dominant wavelength and a distinct target energy; Receiving the measurement result of the energy of the preceding pulse of the light beam; If the preceding light beam pulse is within a specific set of light beam pulses, this includes determining the energy error, which involves comparing the measured energy of the preceding light beam pulse with the specific target energy associated with the specific set of light beam pulses; and This includes adjusting at least one component of the light source, thereby adjusting the energy of subsequent pulses in a particular set of light beam pulses based on a determined energy error. 2. The method according to Clause 1, further comprising receiving each individual target energy associated with each set of light beam pulses. 3. The method according to Clause 1, further comprising categorizing whether a preceding light beam pulse is within a specific set of light beam pulses. 4. The method according to Clause 1, further comprising determining the amount of adjustment for at least one component of the light source. 5. The method according to Clause 1, further comprising correcting the amount of adjustment for at least one component of the light source based on whether a preceding light beam pulse is within a particular set of light beam pulses. 6. The method according to Clause 1, wherein adjusting at least one component of the light source includes changing the voltage supplied to the electrodes associated with the light oscillator of the light source. 7. A light source device including an optical oscillator configured to generate optical pulses having spectral characteristics in response to an excitation signal, and a spectral adjustment device configured to control the spectral characteristics of the optical pulses; and A system comprising an energy control device that communicates with a light source device, the energy control device being configured to determine a target energy associated with the spectral characteristics of a generated optical pulse; and to determine, on at least the determined target energy, to adjust an excitation signal causing an optical oscillator to generate one or more subsequent optical pulses to compensate for a change in the configuration of a spectral adjustment device. 8. The system described in Clause 7, wherein the adjustment of the excitation signal causes an adjustment of the energy of one or more subsequently generated optical pulses. 9. The system described in Clause 7, in which the target energy associated with the spectral characteristics of the generated light pulse is defined in advance as being associated with the spectral characteristics of the generated light pulse. 10. The system as described in Clause 7, wherein the optical oscillator is associated with a plurality of transfer functions, each transfer function associated with a specific configuration of a spectral tuning device and a specific value of spectral characteristics; and the energy control device is configured to determine the adjustment to the excitation signal based on the transfer function associated with a specific configuration of a spectral tuning device used to generate one or more subsequent optical pulses. 11. The spectral adjustment device comprises at least one prism and diffracting elements arranged in optical communication with each other, and each transfer function is associated with a different state of at least one prism, as described in Clause 7. 12. The system described in Clause 7, wherein the spectral characteristics of the light pulse are the central wavelength of the light pulse, and each component of the spectral adjustment device corresponds to a specific value of wavelength. 13. The system described in Clause 7, further comprising a measuring device configured to measure the energy of an optical pulse. 14. The system described in Clause 13, wherein the energy control device is configured to determine the energy error by comparing the target energy with the measured energy, and the decision to adjust the excitation signal is also based on the energy error. 15. The system according to Clause 7, wherein the energy control device is configured to determine adjustment to the excitation signal causing the optical oscillator to generate one or more subsequent optical pulses associated with the spectral characteristics of the generated optical pulse. 16. The system as described in Clause 7, wherein the energy control device is configured to determine a target energy associated with the spectral characteristics of a generated light pulse by receiving a communication from a lithography exposure apparatus configured to receive a light pulse, the communication providing a set of target energies, and each target energy within the set of target energies is associated with a spectral characteristic. 17. An energy control device including a control module, wherein the control module is: Receiving the energy value of a preceding light pulse emitted from a light source; A comparison including comparing the received energy value with the first target energy only when the preceding light pulse is within a first set of light beam pulses associated with a first dominant wavelength; or comparing the received energy value with a second target energy different from the first target energy only when the preceding light pulse is within a second set of light beam pulses associated with a second dominant wavelength different from the first dominant wavelength; and An energy control device configured to adjust at least one component of a light source based on this comparison, thereby adjusting the energy of a subsequent light pulse having a dominant wavelength associated with a preceding light pulse. 18. The energy control device according to Clause 17, comprising a category module configured to categorize whether a preceding optical pulse is within a first set of optical beam pulses or within a second set of optical beam pulses. 19. The energy control device according to Clause 17, comprising a comparator configured to determine whether a preceding optical pulse is within a first set of optical beam pulses or a second set of optical beam pulses, and to provide a first target energy or a second target energy based on this determination. 20. The energy control device according to Clause 17, comprising a control module and a signal module configured to determine the amount of adjustment to be made to at least one component of a light source. 21. The energy control device according to Clause 17, comprising a control module configured to correct the amount of adjustment made to at least one component of the light source based on whether a preceding optical pulse is within a first or second set of optical beam pulses. 22. The energy control device described in Clause 21, wherein the correction module is configured to correct the adjustment amount by applying a filter to the adjustment amount. 23. The energy control device according to Clause 22, comprising a notch filter that transmits information having frequencies within a first frequency band and substantially blocks information having frequencies outside the first frequency band. 24. The energy control device described in Clause 22, wherein the filter includes a Kalman filter. 25. The energy control device described in Clause 21, wherein the correction module is configured to correct a control amount by applying a feedforward correction to the control amount. 26. An energy control device according to Clause 17, comprising a control module configured to adjust at least one component of a light source based on this comparison, thereby adjusting the energy of a subsequent light pulse having a dominant wavelength associated with a preceding light pulse, transmitting a signal to the light source, thereby changing the voltage supplied to an electrode associated with the light oscillator of the light source. 27. An energy control device as described in Clause 17, comprising a control module configured to receive the energy values ​​of a plurality of preceding light pulses emitted from a light source. 28. The energy control device according to Clause 17, wherein the control module is configured to adjust at least one component of the light source based on this comparison, thereby adjusting the energy of a plurality of subsequent light pulses having a dominant wavelength associated with a preceding light pulse. 29. The energy control device described in Clause 17, wherein the control module is configured to maintain the energy of a subsequent light pulse that does not have a dominant wavelength associated with a preceding light pulse based on this comparison.

[0146]

[0174] Other implementation forms are covered by the claims.

Claims

1. A method for controlling the energy of a pulsed light beam, Generating multiple sets of pulses of the light beam from a light source, wherein each set of light beam pulses is associated with a distinct main wavelength and a distinct target energy, The measurement result of the energy of the preceding pulse of the light beam is received, If the preceding light beam pulse is within a specific set of light beam pulses, the energy error is determined by comparing the measured energy of the preceding light beam pulse with the specific target energy associated with the specific set of light beam pulses. A method comprising adjusting at least one component of the light source, thereby adjusting the energy of subsequent pulses in a particular set of light beam pulses based on the determined energy error.

2. The method according to claim 1, further comprising receiving each individual target energy associated with each set of light beam pulses.

3. The method according to claim 1, further comprising determining the amount of adjustment to the at least one component of the light source.

4. The method according to claim 1, further comprising correcting the amount of adjustment to the at least one component of the light source based on whether the preceding light beam pulse is within the particular set of light beam pulses.

5. A light source device, An optical oscillator configured to generate optical pulses having spectral characteristics in response to an excitation signal, configured to generate multiple sets of pulses, each set of pulses associated with a distinct dominant wavelength and a distinct target energy, A spectral adjustment device configured to control the spectral characteristics of the light pulse, A light source device including, An energy control device that communicates with the aforementioned light source device, To determine the target energy associated with the spectral characteristics of the generated light pulse, and The adjustment of the excitation signal to cause the optical oscillator to generate one or more subsequent optical pulses to compensate for changes in the configuration of the spectral adjustment device is determined at least based on the determined target energy. A system comprising an energy control device.

6. The system according to claim 5, wherein the adjustment to the excitation signal causes an adjustment to the energy of the one or more subsequently generated optical pulses.

7. The system according to claim 5, wherein the target energy associated with the spectral characteristics of the generated light pulse is defined in advance as being associated with the spectral characteristics of the generated light pulse.

8. The spectral adjustment device comprises at least one prism and diffracting elements arranged to be optically connected to each other, wherein each transfer function is associated with a different state of at least one prism, according to claim 5.

9. The system according to claim 5, wherein the spectral characteristics of the light pulse are the central wavelength of the light pulse, and each component of the spectral adjustment device corresponds to a specific value of the wavelength.

10. The system according to claim 5, further comprising a measuring device configured to measure the energy of the light pulse, wherein the energy control device is configured to determine an energy error by comparing the target energy with the measured energy, and the determination of the adjustment for the excitation signal is also based on the energy error.

11. The system according to claim 5, wherein the energy control device is configured to determine the target energy associated with the spectral characteristics of the generated light pulse by receiving a communication from a lithography exposure apparatus configured to receive the light pulse, the communication provides a set of target energies, and each target energy in the set of target energies is associated with a spectral characteristic.

12. An energy control device including a control module, The control module is Receiving the energy value of the preceding light pulse emitted from the light source, The purpose is to make a comparison, The received energy value and the first target energy are compared only if the preceding light pulse is a first set of light beam pulses included in the light beam from the light source and is within the first set of light beam pulses associated with a first main wavelength, or The received energy value is compared with a second target energy different from the first target energy, but only if the preceding light pulse is within a second set of light beam pulses included in the light beam from the light source and associated with a second main wavelength different from the first main wavelength. Performing comparisons that include, Adjusting at least one component of the light source based on the comparison, thereby adjusting the energy of the subsequent light pulse having the main wavelength associated with the preceding light pulse, An energy control device configured to perform the following actions.

13. The energy control device according to claim 12, wherein the control module includes a comparator configured to determine whether the preceding optical pulse is within the first set of optical beam pulses or within the second set of optical beam pulses, and to provide the first target energy or the second target energy based on the determination.

14. The energy control device according to claim 12, wherein the control module includes a signal module configured to determine the amount of adjustment made to at least one component of the light source.

15. The energy control device according to claim 12, wherein the control module includes a correction module configured to correct the amount of adjustment made to the at least one component of the light source based on whether the preceding light pulse is within the first or second set of light beam pulses.

16. The energy control device according to claim 15, wherein the correction module is configured to correct the adjustment amount by applying a filter to the adjustment amount.

17. The energy control device according to claim 16, wherein the filter includes a notch filter that transmits information having frequencies within a first frequency band and substantially blocks information having frequencies outside the first frequency band.

18. The energy control device according to claim 16, wherein the filter includes a Kalman filter.

19. The energy control device according to claim 15, wherein the correction module is configured to correct the adjustment amount by applying feedforward correction to the adjustment amount.

20. The energy control device according to claim 12, wherein the control module is configured to adjust at least one component of the light source based on the comparison, thereby adjusting the energy of the subsequent light pulse having the dominant wavelength associated with the preceding light pulse, and is configured to transmit a signal to the light source, thereby changing the voltage supplied to an electrode associated with the optical oscillator of the light source.

21. The energy control device according to claim 12, wherein the control module is configured to adjust at least one component of the light source based on the comparison, thereby adjusting the energy of a plurality of subsequent light pulses having the main wavelength associated with the preceding light pulse, and the control module is configured to maintain the energy of subsequent light pulses not having the main wavelength associated with the preceding light pulse based on the comparison.

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