TW202036174A - Dose control for an extreme ultraviolet optical lithography system - Google Patents

Abstract

An apparatus for an extreme ultraviolet (EUV) lithography system includes an optical modulation system including at least one optical element configured for placement on a beam path between the optical modulation system and a plasma formation region configured to receive target material that emits EUV light in a plasma state; and a control system configured to be coupled to the optical modulation system and to receive a signal including an indication of a characteristic of exposure light impinging on a wafer in a scanning system of the lithography system. The control system is further configured to adjust the optical modulation system based on the indication of the characteristic of the exposure light to thereby control a property of a first portion of a light beam based on the characteristic of the exposure light, the light beam including at least the first portion and a second portion.

Description

Dose control for extreme ultraviolet photolithography system

The present invention relates to dose control for extreme ultraviolet (EUV) photolithography devices.

Extreme ultraviolet ("EUV") light, for example, a wavelength of 100 nanometers (nm) or less (sometimes called soft x-rays) and includes a wavelength of, for example, 20 nm or less, between 5 nm and 20 nm Electromagnetic radiation of light between or between 13 nm and 14 nm can be used in photolithography procedures to create very small features in substrates (such as silicon wafers) by initial polymerization in the resist layer .

Methods for generating EUV light include, but are not necessarily limited to: using emission lines in the EUV range to convert materials including elements such as xenon, lithium, or tin into a plasma state. In one such method, often referred to as laser-generated plasma ("LPP"), an amplified light beam that can be called a driving laser can be used to irradiate material droplets, plates, ribbons, etc. Target materials in the form of streams or clusters are used to generate the required plasma. For this procedure, plasma is usually generated in a sealed container such as a vacuum chamber, and various types of metrology equipment are used to monitor the plasma.

In one aspect, an apparatus for an extreme ultraviolet (EUV) lithography system includes: an optical modulation system that includes at least one optical element configured to be placed in the optical modulation system On a beam path between the variable system and a plasma forming area configured to receive a target material that emits EUV light in a plasma state; and a control system configured as a coupling It is connected to the optical modulation system and receives a signal including an indication of a characteristic of exposure light irradiated on a wafer in a scanning system of the lithography system. The control system is further configured to adjust the optical modulation system based on the indication of the characteristic of the exposure light to thereby control a property of a first part of a light beam based on the characteristic of the exposure light, the light beam comprising At least the first part and the second part.

Implementations can include one or more of the following features.

The device may also include a dose sensor coupled to the control system, the dose sensor being configured to: sense the exposure light at the wafer and include the indication of the characteristic of the exposure light The signal is provided to the control system. The dose sensor can be positioned relative to the wafer in the scanning system of the lithography system.

The optical modulation system can be configured to generate a modified optical pulse that includes a base portion and a main portion, and the first portion of the light beam can include the base portion and the second portion of the light beam can include the The main part enables the control system to be configured to adjust the modulation system to thereby control at least one attribute of the base part based on the characteristic of the exposure light. The at least one attribute of the base portion may be a time interval, an average intensity and/or a maximum intensity. The main portion of the modified pulse may have an energy sufficient to convert at least some of the target material into plasma that emits EUV light. The optical modulation system may include an electro-optical modulator (EOM), and at least one optical element may include an electro-optical material. The EOM may include a first electrode and a second electrode, and the electro-optical material is interposed between the first electrode and the second electrode. The control system being configured to adjust the at least one optical element may include the control system being configured to: adjust an amount of voltage applied to the electro-optical material by the first electrode and the second electrode and/or adjust the amount of voltage applied by the first electrode and the second electrode A time for an electrode and the second electrode to apply a voltage to the electro-optical material. The at least one optical element of the modulation system further includes at least one polarization element configured to be placed on the beam path, and the control system configured to adjust the at least one optical element may include the control system being configured State to move the polarization element. The control system configured to adjust the at least one optical element may also include the control system configured to: adjust the amount of voltage applied to the electro-optical material by the first electrode and the second electrode and/or adjust the The first electrode and the second electrode apply a voltage to the electro-optical material for a time. The optical system may include more than one EOM, and each EOM is between two polarization elements.

In some implementations, the control system is further configured to: during an inactive period, cause the first electrode and the second electrode to apply a non-zero bias voltage to the electro-optic material, and during an active period , The control system is configured to cause the first electrode and the second electrode to apply a second voltage greater than the bias voltage to the electro-optical material, and an amplitude of the bias voltage is based on the characteristic of the exposure light The indication and the attribute of the base are at least partially determined by the amplitude of the bias. The at least one optical element of the optical modulation system may also include an acousto-optic modulator (AOM), the AOM is between the optical modulation system and the plasma formation region, and the AOM is configured to Determine one time interval of this base.

In some implementations, the light beam includes a plurality of pulses, the first portion of the light beam includes a first pulse in the plurality of pulses, and the second portion of the light beam includes a second pulse in the plurality of pulses, The control system is configured to adjust the modulation system to thereby control at least one attribute of the first pulse among the plurality of pulses based on the characteristic of the exposure light. All the plural pulses can propagate on the beam path. The first part of the light beam and the second part of the light beam can be generated by different light sources.

The indication of a characteristic of the exposure light may include an indication of a dose of EUV light at a specific portion of the wafer, and the dose of EUV light at the wafer includes the wafer within a predetermined amount of time The total amount of EUV light at that specific part. The control system may be further configured to analyze the indication to determine whether a threshold dose of EUV light has been delivered to the specific part of the wafer, and if the threshold dose has been delivered to the wafer For a specific part, a command is issued to cause the wafer to move relative to the EUV light so that a different part of the wafer receives the EUV light.

The device may also include a light generating module configured to generate the light beam, the light generating module including a gain medium and an energy source configured to excite the gain medium. In these implementations, the control system is coupled to the light generating module, and the control system is further configured to: control the energy source so that an energy of the light beam is substantially the same throughout a time window, and the control system is Configuring to adjust the modulation system includes that the control system is configured to adjust the modulation system such that an energy of the first portion of the light beam is substantially the same throughout the time window.

In another aspect, an extreme ultraviolet (EUV) light source includes: a container configured to form a vacuum space; a target supply device configured to provide a target to an electric source in the container A plasma generating area; an optical device comprising one or more optical elements configured to be placed on a beam path between the light generating module and the plasma generating area; and A control system coupled to the optical device, the control system being configured to control the optical device to thereby control one or more attributes of a first part of a light beam, the light beam including at least the first part and a first part Two parts. In operational use, the container is configured to provide EUV light to a lithography device, the lithography device is configured to guide the EUV light toward a wafer, and the one or more of the first part The control of attributes is based on a characteristic of the EUV light at the wafer.

Implementations can include one or more of the following features. The EUV light source may also include a light generating module that includes a gain medium and an energy source configured to excite the gain medium. The energy source may include a plurality of electrodes configured to be driven by a radio frequency (RF) power source, and the light generating module includes a chamber containing the plurality of electrodes, and the control system does not adjust the RF power source In the case of any attribute, the one or more attributes of the first part of the beam are controlled.

The optical device may include an optical modulation system configured to generate a modified optical pulse, the modified pulse may include a base portion and a main portion, and the first portion of the light beam may include the base portion and The second part of the light beam includes the main part, and the control system can be configured to control the optical device to thereby control one or more properties of the base part.

The EUV light source may also include a light generating module, and the light generating module may be configured to generate a pulsed light beam including a plurality of pulses. The first part of the light beam may include one of the pulses. One pulse, and the second part of the beam can include one of the second pulses of the plurality of pulses, and the control system can be configured to adjust the optical device to thereby be based on the EUV light at the wafer Characteristics to control at least one attribute of the first pulse among the plurality of pulses.

The EUV light source may also include a light generating module, and the light generating module may include at least a first optical source and a second optical source, and the first part of the light beam may be one generated by the first optical source Optical pulse, and the second part of the light beam can be an optical pulse generated by the second optical source.

The EUV light source may also include a dose sensor coupled to the control system, the dose sensor being configured to sense the characteristic of the EUV light at the wafer and generate the EUV at the wafer An indication of this characteristic of light.

In another aspect, an extreme ultraviolet (EUV) lithography system includes: a container configured to form a vacuum space; and a target supply device configured to provide a target to the container A plasma generating area; an optical device comprising one or more optical elements configured to be placed on a beam path between the light generating module and the plasma generating area ; A lithography device, which is configured to receive EUV light from the container and guide the EUV light toward a wafer; and a control system, which is coupled to the optical device, the control system is configured to control The optical device controls one or more attributes of a first part of a light beam, and the light beam includes at least the first part and a second part. In operational use, the control of the one or more attributes of the first part is based on a characteristic of the EUV light at the wafer.

The implementation of any of the technologies described above may include an EUV light source, a lithography system, a system, a method, a program, a device, or a device. One or more implementation details are set forth in the accompanying drawings and description below. Other features will be obvious from the description and drawings and from the scope of the patent application.

System, and its full text is incorporated herein by reference.

FIG. 1 is a block diagram of the EUV lithography system 100. The lithography system 100 includes an EUV light source 101 that provides EUV light 197 to the lithography device 180. The lithography device 180 shapes, controls, and guides the EUV light 197 and/or focuses the EUV light 197 into an exposure beam 191. The exposure beam 191 irradiates the substrate 192 to form microelectronic features on the substrate 192. The system 100 also includes a control system 150. The control system 150 controls the modulation system 140 based on the indication 154 of the characteristics of the exposure beam 191. In FIG. 1, a line with a dashed-dotted-dashed line style represents a data link on which data, commands, and/or information flow as, for example, electrical signals or as optical signals encoded with information. The data link can be any type of medium capable of carrying information. For example, the data link can be a cable, optical fiber, and/or wireless connection.

The modulation system 140 includes an optical element 142 that interacts with the light beam 107 generated by the optical source 104 to modify the properties (eg, intensity) of the light beam 107 and generate a modified light beam 108. The modified light beam 108 propagates on the path 106 to the plasma formation region 123 to interact with the target 121 including the target material. This interaction converts at least some of the target materials in target 121 into plasma 196, which emits EUV light 197.

Because the EUV light 197 is formed by the interaction between the light beam 107 and the target 121, controlling the properties of the light beam 107 also allows the characteristics of the EUV light 197 to be controlled. In addition, because the exposure beam 191 is based on the portion of the EUV light 197 that is guided to the lithography device 180, controlling the properties of the beam 107 also allows the properties of the exposure beam 191 to be controlled. For example, the dose of the exposure beam 191, which is the amount of light energy delivered to the substrate 192 in a period of time, can be controlled by controlling the properties of the beam 107. As discussed below, the control system 150 implements a technique in which a single parameter of the light beam 107 is modulated by the modulation system 140 to control the characteristics of the EUV light 197 and the exposure light beam 191.

Other techniques for controlling the amount of EUV light 197 and the dose in the EUV light source are known to us. For example, the optical source 104 includes a gain medium 102 that is excited by an energy source 103 to generate a light beam 107. The energy source 103 may be, for example, a pair of electrodes on both sides of the gain medium. In these implementations, the electrodes are driven by a radio frequency (RF) power supply that imparts energy to the electrodes to form a discharge that excites the gain medium. Some previous systems modulate the energy source 103 (for example, by periodically increasing the voltage applied to the electrodes) to modulate the energy of the light beam 107 and make corresponding changes in the amount and dose of EUV light 197. However, modulating the energy source 103 will also change many properties of the light beam 107. For example, the modulated energy source 103 can change the energy, direction, and size of the beam 107. All these attributes are related to the generation of EUV light 197. As a result, it can be challenging to stabilize the amount of EUV light generated by modulating the energy source 103. Although additional feedback loops can be used to mitigate the effects of unintentionally modulating various properties of the light beam 107, such feedback loops increase complexity and reduce reliability.

On the other hand, the control system 150 implements a technique of controlling the EUV light 197 generated by using the modulation system 140 to modulate one or more of the properties of the light beam 107 without relying on the modulated energy source 103. Therefore, the actuation or modulation of the parameters is accomplished in a manner independent of other parameters of the beam 107 related to EUV generation. Therefore, the approach implemented by the control system 150 does not require a separate control loop to control unwanted changes in other parameters of the light beam 107.

Although the control system 150 does not need such a separate control loop to correct for undesired or indirect changes in EUV production, the control system 150 may allow the use of separate and/or additional control loops, which are less effective when used before. The system approach can be challenging or impossible to implement using the previous system approach. For example, previous systems may not have inter-pulse actuators to control the properties of the beam 107 or the properties of a portion of the beam 107. The portion of the beam 107 may be a pulse of the beam 107 or a pedestal portion of the pulse, such as the pedestal portion 366 (FIG. 3C). The control system 150 allows for inter-pulse actuation of parts of the beam 107, which allows the use of control loops (such as dose-based, total energy in the pulses of the beam 108) to control the base part that were not possible in previous systems.

In addition, the technology implemented by the control system 150 has a minimal effect on the thermal state of the optical source 104. Relying on the approach of modulating the energy source 103 causes the output energy of the optical source 104 to vary by a relatively large amount, for example, about 100 millijoules (mJ). The large change in output energy affects the thermal state of the optical source 104 and the optical elements on the path 106. On the other hand, because the control system 150 implements the method of modulating the light beam 107, the intensity of the light beam 107 can be adjusted by a relatively small amount, for example, less than about 5 mJ, so that the amount of EUV light 197 generated can be changed. This leads to greater thermal stability.

In addition, the control system 150 can use the modulation system 140 to modulate the light beam 107 faster than using the energy source 103. For example, in an implementation where the optical source 104 generates optical pulses at a repetition rate of 50 kilohertz (kHz), the energy source 103 can be modulated every ten optical pulses. In contrast, the modulation system 140 can be modulated at 50 kHz, and therefore the properties on each pulse generated by the optical source 104 can be adjusted. Therefore, the control system 150 can finely and accurately control the modulation of the light beam 107 and this can lead to an overall improvement in system performance.

2A and 2B are block diagrams of lithography systems 200A and 200B, respectively. In FIGS. 2A and 2B, lines with a dashed-dotted-dashed line style represent data links on which data, commands, and/or information flow as, for example, electrical signals or as optical signals encoded with information. The data link can be any type of medium capable of carrying information. For example, the data link can be a cable, optical fiber, and/or wireless connection.

Referring to FIG. 2A, the lithography system 200A is an implementation example of the lithography system 100 (FIG. 1). The lithography system 200A includes an EUV light source 201A that provides EUV light 197 to the lithography device 280. The lithography device 280 uses the exposure beam 191 to expose the substrate 192.

The lithography system 200A includes an optical source 204 that generates a light beam 207. The optical source 204 includes a gain medium 202 and an energy source 203 that excites the gain medium 202 to generate a light beam 207. The beam 207 may be a pulsed beam including a plurality of optical pulses separated in time, or a continuous wave (CW) beam. The optical source 204 may be, for example, a pulsed (for example, Q-switching) or continuous wave carbon dioxide (CO ₂ ) laser or a solid state laser (for example, a Nd:YAG laser or an Erbium-doped fiber (Er: glass) laser).

The lithography system 200A also includes a modulation system 240. The modulation system 240 is any type of device capable of changing or modulating the properties of the light beam 207. For example, the modulation system 240 may be an electro-optical modulator (EOM), an acousto-optical modulator (AOM), or a combination of these devices. The modulation system 240 includes an optical element 242. The light beam 207 is incident on the optical element 242. The interaction between the optical element 242 and the light beam 207 will modify the properties of the light beam 207 to produce a modified light beam 208. Examples of the modulation system 240 are discussed in relation to FIGS. 3A, 4, and 5. The EUV light source 201A also includes an optical amplifier system 230 between the optical modulation system 240 and the plasma formation region 223. The optical amplifier system 230 includes one or more optical amplifiers on the beam path 206. Each optical amplifier includes a gain medium that amplifies the wavelength of the modified light beam 208. The modified light beam 208 propagates to the plasma formation region 223 through the optical amplifier system 230.

The EUV light source 201A includes a supply system 220 that generates a target stream 222. The target in the stream 222 travels toward the plasma formation region 223 in the vacuum chamber 211. In the example of FIG. 2A, the target 221 (which is part of the stream 222) is in the plasma formation region 223. Each target in the stream 222 includes a target material, which is any material that emits EUV light when in a plasma state. For example, the target material may include water, tin, lithium, and/or xenon. Other materials can be used as target materials. For example, elements can be used as pure tin, tin (of Sn); as tin compounds, e.g. _{SnBr 4, SnBr 2, SnH 4} ; as tin alloys such as tin - gallium alloy, tin - indium alloys, tin - indium - Gallium alloy or any combination of these alloys. In addition, the target material may be a target mixture, which includes impurities that do not emit EUV light when in a plasma state, such as non-target particles or inclusion particles. For example, the non-target particles or inclusion particles may be tin oxide (SnO ₂ ) particles or tungsten (W) particles.

The interaction between the modified light beam 208 and the target 221 produces a plasma 196, which emits EUV light 197. EUV light 197 interacts with optical element 213, which guides at least some of EUV light 197 to lithography device 280. The optical element 213 may be a collector mirror with an aperture through which the modified light beam 208 propagates, and the curved reflective surface faces the plasma forming region 223 and reflects and focuses on wavelengths in the EUV range.

The lithography device 280 includes a plurality of reflective optical elements 281 and 282, a mask 284 and a slit 283, which are all in the enclosure 286. The enclosure 286 is a shell, tank, or other structure that can support the reflective optical elements 281 and 282, the mask 284, and the slit 283, and can also maintain the vacuum space in the enclosure 286.

The EUV light 197 enters the enclosure 286 and is reflected by the optical element 281 through the slit 283 toward the mask 284. The slit 283 is the shape of the scattered light used to scan the wafer in the lithography process. The size of the gap 283 is a physical quantity. The dose delivered to the substrate 192 or the number of photons delivered to the substrate 192 depends on the size of the slit 283 and the speed at which the slit 283 is scanned.

The mask 284 may also be referred to as a reduction mask or a patterned device. The mask 284 includes a spatial pattern representing the electronic features to be formed on the substrate 192. The EUV light 197 interacts with the mask 284. The interaction between the EUV light 197 and the mask 284 causes the pattern of the mask 284 to be imparted to the EUV light 197 to form an exposure beam 191. The exposure light beam 191 passes through the slit 283 and is guided to the substrate 192 by the optical element 282. The interaction between the substrate 192 and the exposure beam 191 exposes the pattern of the mask 284 to the substrate 192, and electronic features are formed on the substrate 192 thereby. The substrate 192 includes a plurality of parts 293 (eg, dies). The area of each part 293 in the Y-Z plane is smaller than the area of the entire substrate 192 in the Y-Z plane. Each part 193 may be exposed by the exposure beam 191 to include a copy of the photomask 284, so that each part 193 includes the electronic features indicated by the pattern on the photomask 284.

The lithography system 200A also includes a metrology system 260. The metrology system 260 includes a sensor system 262. The sensor system 262 includes one or more sensors. The sensor system 262 also includes an electronic component module 264 coupled to the sensor system 262. The sensor system 262 may include a camera, a sensor, a detector, or any combination of such devices that are sensitive to the EUV wavelength in the exposure beam 191. The sensor system 262 may include a sensor at the substrate 191 that is positioned so that it can monitor the light irradiated on the substrate or so that it can monitor the light related to the light irradiated on the substrate. The sensor system 262 may include a sensor configured to measure EUV light 197 in the vacuum chamber 211 or at the entrance of the enclosure 286 (for example, at the optical element 281).

The electronic component module 264 includes electronic components for operating the sensor system 262. For example, the electronic component module 264 may include an electronic processor capable of driving the sensor system 262 to perform certain actions and obtaining data from the sensor system 262. In addition, the electronic component module 264 generates an indication or representation 254 of one or more characteristics (such as intensity or energy) of the exposure beam 191. For example, the indication 254 may include numerical data representing the intensity or light energy at the substrate 192. In addition, the instructions 254 may also include data describing this information. For example, the indication 254 may include the time period during which the information is collected.

The metrology system 260 is coupled to the control system 250. The control system 250 exchanges data and/or information with the metrology system 260 and the modulation system 240 via the communication interface 253. For example, the control system 250 receives the instruction 254 and provides a trigger or command signal to the modulation system 240 based on the instruction 254. In addition, although the control system 250 does not rely on the modulation of the energy source 203 to modulate the properties of the light beam 207, the control system 250 can exchange data and/or information with the optical source 204. In the implementation of the interaction between the control system 250 and the optical source 204, there is a data link between the optical source 204 and the control system 250.

The control system 250 includes an electronic processor 251, an electronic storage 252 and a communication interface 253. The electronic processor 251 includes one or more processors suitable for executing computer programs, such as general or special-purpose microprocessors, and any type or types of digital computers. Generally, electronic processors receive commands and data from read-only memory, random access memory, or both. The electronic processor 251 can be any type of electronic processor.

The electronic storage 252 may be a volatile memory such as RAM, or a non-volatile memory. In some implementations, the electronic storage 252 includes non-volatile and volatile parts or components. The electronic storage 252 can store data and information used in the operation of the control system 250 and/or components of the control system 250. For example, the electronic storage 252 may store a dosage specification indicating an acceptable dosage for a portion 293. The dosage specification can be a single value or a range of values. The electronic storage 252 can also store instructions (for example, a sequence of instructions that together form a computer program, a software module, or a callable function). When executed, these instructions cause the processor 251, the control system 250, the modulation system 240, and the measurement system 260 and/or component communication in the lithography device 280. In addition, the electronic storage 252 can store instructions designated for the data processing technology of the analysis instructions 254.

The communication interface 253 allows the control system 250 to receive data and signals and/or provide data and signals to the operator, the modulation system 240, the optical source 204, the metrology system 260, and/or an automatic processing program executed on another electronic device Any kind of electronic interface. For example, the communication interface 253 may include a visual display, a keyboard, a network connection (such as an Ethernet connection), and/or a device capable of receiving audible commands and/or generating audio output.

The metrology system 260 and the control system 250 are shown as separate items in the example of FIG. 2A. However, all or part of the metrology system 260 may be implemented as part of the control system 250. For example, the electronic component module 264 can be implemented by the electronic processor 251 by instructions stored in the electronic storage 252.

FIG. 2B is a block diagram of the lithography system 200B. The lithography system 200B is the same as the system 200A (FIG. 2A), except that the lithography system 200B includes an optical source 204B, which includes a first optical source 204_1 emitting a first light beam 207_1 and a second optical source 204_2 emitting a second light beam 207_2 except. The light beams 207_1 and 207_2 may be pulsed light beams. The pulse of the beam 207_2 may be referred to as a pre-pulse, and the pulse of the beam 207_1 may be referred to as a main pulse. The light beams 207_1 and 207_2 interact with the modulation systems 240_1 and 240_2, respectively. The modulation systems 240_1 and 240_2 are part of the modulation system 240B.

The beam 207_2 propagates to the initial target area 223_2 in the vacuum chamber 211. The initial target area 223_2 is displaced in the −x direction relative to the plasma forming area 223 and is located between the plasma forming area 223 and the supply system 220. The initial target area 223_2 receives one of the targets in the stream 222. In the example of FIG. 2B, the target in the initial target area 223_2 is marked as 221i and is called the initial target 221i.

The light beam 207_2 interacts with the modulation system 240_2 to form a modified light beam 208_2. The modified light beam 208_2 interacts with the initial target 221i at the initial target area 223_2 to adjust the target 221i and form a modified target 221m. The modified target 221m drifts to the plasma formation region 223 and is irradiated by the beam 207_1 to form the plasma 196. Compared to the unregulated target, the modified target 221m is easier to absorb light energy, and the higher part of the target material in the modified target 221m is converted into plasma 196. For example, the interaction between the light beam 207_2 and the target 221i can change the shape, volume and/or size of the target material distribution in the initial target 221i, and/or can reduce the density of the target material along the propagation direction of the light beam 207_1 gradient. All these changes enhance the ability of the modified target 221m to absorb light energy from the beam 207_1 and increase the amount of target material converted into plasma 196. The modified target 221m may be, for example, a disk-shaped distribution of target material having a larger volume than the target 221i. The reduced density causes a higher portion of the target material in 221m to be converted into plasma 196 and therefore a greater amount of EUV light.

The control system 250 is coupled to the modulation system 240B. In this way, the control system 250 can be used to control the adjustment parameters of the initial target 221i. For example, the control system 250 can control the properties of the modified light beam 208_2, such as intensity and/or time span.

The optical sources 204_1 and 204_2 can be, for example, two lasers. For example, the optical sources 204_1 and 204_2 may be two carbon dioxide (CO ₂ ) lasers. In other implementations, the optical sources 204_1 and 204_2 may be different types of lasers. For example, the optical source 204_2 may be a solid state laser, and the optical source 204_1 may be a CO ₂ laser. The light beams 207_1, 207_2 may have different wavelengths. For example, in an implementation where the optical sources 204_1 and 204_2 include two CO ₂ lasers, the wavelength of the first beam 207_1 may be about 10.26 micrometers (µm) and the wavelength of the second beam 207_2 may be between 10.18 µm and 10.26 µm between. The wavelength of the second light beam 207_2 may be about 10.59 µm. In these implementations, the beams 207_1 and 207_2 are generated from different lines of the CO ₂ laser, resulting in the beams 207_1 and 207_2 having different wavelengths, even though the two beams are both generated from the same type of source.

The beams 207_1 and 207_2 have different energies and may have different durations. For example, the pulse (or pre-pulse) of the beam 207_2 may have a duration of at least 1 nanosecond (ns), for example, the pre-pulse may have a duration of 1 ns to 100 ns and a wavelength of 1 µm or 10 µm . In one example, the pre-pulse of radiation is a laser pulse with an energy of 15 mJ to 60 mJ, a pulse duration of 20 ns to 70 ns, and a wavelength of 1 µm to 10 µm. In some examples, the pre-pulse may have a duration of less than 1 ns. For example, the pre-pulse may have a duration of 300 picoseconds (ps) or less, 100 ps or less, 100 ps to 300 ps, or 10 ps to 100 ps.

In the example of FIG. 2B, the first beam 207_1 and the second beam 207_2 interact with the separate modulation system and travel on separate optical paths. However, in other implementations, the first beam 207_1 and the second beam 207_2 may share all or part of the same optical path and may also share the same beam delivery system.

Referring also to FIG. 2C, the optical source 204, the optical source 204_1, and/or the optical source 204_2 may include more than one light source. FIG. 2C is a block diagram of a lithography system 200C including an EUV light source 201C and an optical source 204C. The optical source 204C can be used as the optical source 204_1 and/or the optical source 204_2. The EUV light source 201C may be the EUV light source 201A (FIG. 2A) or the EUV light source 201B (FIG. 2B).

The optical source 204C includes a first optical source 204_1C, a second optical source 204C_2, and a beam combiner 205. The beam combiner guides the beam 207C_1 emitted by the first optical source 204C_1 and the beam 207C_2 emitted by the second optical source 204C_2 toward Optical modulation system 240. The beam combiner 205 may be, for example, one or more refractive and/or reflective devices (such as mirrors, lenses, and/or mirrors). The light beams 207C_1 and 207C_2 interact with the modulation system 240 to form a modified light beam 208C. The lights 207C_1 and 207C_2 are pulsed beams.

The optical sources 204C_1 and 204C_2 may be the same or may be different from each other. The optical sources 204C_1 and 204C_2 can be, for example, two lasers. For example, the optical sources 204C_1 and 204C_2 may be two carbon dioxide (CO ₂ ) lasers. In other implementations, the optical sources 204C_1 and 204C_2 may be different types of lasers. For example, the optical source 204C_2 may be a solid-state laser, and the optical source 204_1 may be a CO ₂ laser. The light beams 207C_1, 207C_2 may have different wavelengths. For example, in an implementation where the optical sources 204C_1 and 204C_2 include two CO ₂ lasers, the wavelength of the first beam 207C_1 may be about 10.26 micrometers (µm) and the wavelength of the second beam 207C_2 may be between 10.18 µm and 10.26 µm between. The wavelength of the second light beam 207C_2 may be about 10.59 µm. In these implementations, the light beams 207C_1 and 207C_2 are generated from different lines of the CO ₂ laser, resulting in the light beams 207C_1 and 207C_2 having different wavelengths, even though both light beams are generated from the same type of source.

In the example shown, the beams 207C_1 and 207C_2 are guided by the beam combiner 205 to substantially the same beam path. However, the optical source 204C can be implemented without the beam combiner 205. In these implementations, the light beams 207C_1 and 207C_2 propagate on separate paths.

As mentioned above, the optical source 204C can be used as the optical source 204, 204_1 and/or the optical source 204_2. Therefore, the light beam 207 for the EUV light source 201A (FIG. 2A) can be generated by light from two separate light sources. In addition, light beam 207_1 and/or light beam 207_2 (FIG. 2B) can be generated by light from two separate light sources. As discussed below, the light generated by a separate light source in these implementations can be considered part of the base.

FIG. 3A shows a block diagram of the modulation system 340. The modulation system 340 is an example of a modulation system that can be used as the modulation system 140, 240, 240_1, or 240_2. The modulation system 340 includes an electro-optic modulator that modulates the light beam 307 based on the electro-optic effect to generate a modified light beam 308. The beam 307 may be the beam 107, 207, 207_1, or 207_2, respectively, and the modified beam 308 may be the modified beam 108, 208, 208_1, or 208_2, respectively.

The modulation system 340 includes an optical element 342 between the electrodes 344a, 344b. The optical element 342 is any material that experiences electro-optical effects. The electro-optical effect describes the change in the refractive index of the electro-optical material 342 caused by applying a direct current (DC) or low-frequency electric field or potential difference 343 across the electro-optical material 342. The electrodes are coupled to a power source 345, and the power source 345 generates a potential difference 343 by keeping the electrodes 344a and 344b at different voltages. The power supply 345 may be, for example, a voltage source, a function generator, or a power supply. The electrodes 344a, 344b are controllable to form an electric field 343. For example, the control system 150 may cause the power supply 345 to provide a voltage signal 347 to the electrode 344a so that the electrode 344a remains at a different voltage from the electrode 344b, thus generating an electric field or potential difference (V) 343 across the electro-optic material 342.

By controlling the electro-optic effect in the electro-optic material 342 when the light beam 307 is incident on the electro-optic material 342, the modulation system 340 modulates the phase, polarization, or amplitude of the light beam 307 to form a modified light beam 308. The potential difference 343 can be used to control whether the modulation system 340 transmits light. The electric field 343 can be used to control the electro-optical material 342 so that only a certain part or some parts of the light beam 107 pass through the electro-optical material 342. In this way, the modulation system 340 forms a pulse 308 (modified beam) from a portion of the beam 107. The pulse 308 propagates to the vacuum chamber 211 and the vacuum chamber 211 receives the stream 122 of the target. The pulse 308 interacts with the target, and the interaction converts at least some of the target material in the target into a plasma 196 that emits EUV light 197.

The modulation system 340 also includes one or more polarization-based optical elements 346. In the example of FIG. 3A, only one polarization-based optical element 346 is shown. However, in other implementations, additional polarization-based optical elements 346 may be included. For example, the second polarization-based optical element 346 can be on the side of the modulation system 340 that receives the light beam 107. In addition, the polarization-based optical element 346 is shown physically separate from the electro-optic material 342, but other implementations are possible. For example, the polarization-based optical element 346 may be a film formed on the electro-optical material 342 so that the polarization-based optical element 346 and the electro-optical material 342 are in contact with each other.

The polarization-based optical element 346 is any optical element that interacts with light based on the polarization state of light. For example, the polarization-based optical element 346 may be a linear polarizer that transmits horizontally polarized light and blocks vertical polarized light or transmits vertically polarized light and blocks horizontally polarized light. The polarization-based optical element 346 may be a polarization beam splitter that transmits horizontally polarized light and reflects vertically polarized light. The polarization-based optical element 346 may be an optical element that absorbs all light except for light with a specific polarization state. In some implementations, the polarization-based optical element 346 may include a quarter wave plate. At least one polarization-based optical element 346 is positioned to receive light passing through the electro-optical material 342 and direct light of a certain polarization state onto the beam path 106.

The electro-optical material 342 can be any material that transmits one of the multiple wavelengths of the light beam 307. For implementations where the beam 307 includes light with a wavelength of 10.6 microns (µm), the electro-optical material 342 may be, for example, cadmium zinc telluride (CdZnTe or CZT), cadmium telluride (CdTe), zinc telluride (ZnTe) and/or arsenide Gallium (GaAs). Other materials can be used at other wavelengths. For example, the material 342 may be monopotassium phosphate (KDP), ammonium dihydrogen phosphate (ADP), quartz, cuprous chloride (CuCl), zinc sulfide (ZnS), zinc selenide (ZnSe), lithium niobate ( LiNbO ₃ ), gallium phosphide (GaP), lithium tantalate (LiTaO ₃ ), or barium titanate (BaTiO ₃ ). Other materials that transmit one or more wavelengths of the light beam 307 and exhibit birefringence in response to an external force can also be used as the electro-optical material 342. For example, quartz can be used as the electro-optical material 342.

The electro-optical material 342 also exhibits anisotropy. In a material exhibiting anisotropy, the properties of the material (such as refractive index) are not uniform in space. Therefore, the properties of the electro-optic material 342 can be modified along one or more specific directions by applying a controllable external force (such as a potential difference (343)). For example, the refractive index of different polarization components of light propagating through the material 342 can be controlled by applying an external force. Therefore, the polarization state of the light passing through the material 342 can be controlled by controlling the potential difference (V) between the electrodes 344a and 344b.

Under ideal operation, the modulation system 340 transmits light only when the potential difference 343 applied to the electro-optical material 342 causes the polarization state of the light passing through the electro-optical material 342 to match the polarization condition of the polarization-based optical element 346. For example, if the polarization-based optical element 346 is a linear polarizer positioned to transmit horizontally polarized light to the beam path 106, and the beam 307 is vertically polarized when it is initially incident on the electro-optic material 342, only The pulse 308 is formed when the potential difference 343 applied to the electro-optical material 342 changes the polarization state of the beam 307 so that the beam 307 becomes horizontally polarized before interacting with the polarization-based optical element 346.

Whenever the modulation system 340 is controlled to transmit light intentionally, the modulation system 340 is considered to be in an on state or activated. For example, when the applied potential difference 343 rotates the polarization state of the beam 307 to match the polarization-based optical element 346, the optical modulation system 340 is considered to be in the on state and a pulse 308 is formed. When the potential difference 343 is applied such that the polarization state of the expected beam 307 is orthogonal to the polarization-based optical element 346, the optical modulation system 340 is turned off or not activated. Under ideal conditions, when the optical modulation system 340 is in the off state, the light beam 307 does not pass through the modulation system 340.

However, applying the potential difference 343 to the electro-optical material 342 causes sound waves to propagate in the electro-optical material 342. These sound waves can continue after the potential difference 343 is removed from the electro-optical material 342. In addition, acoustic waves cause strains in the electro-optical material 342, which strains change the optical properties of the electro-optical material 342 and allow incident light to pass through the modulation system 342 (as an optical leak), even when the potential difference 343 is not applied. Therefore, in actual operation, the modulation system 340 can transmit stray light (optical leakage), even if the polarization condition of the polarization-based optical element 346 is such that the light incident on the electro-optical material 342 should not pass through the modulation system The same was true at 340. For example, when the optical leakage exists just before the formation of the pulse 308, the optical leakage pulse 308 forms a pedestal portion.

Referring also to FIGS. 3B and 3C, an illustration of an example of the pulse of the light beam 307 and an example of a modified optical pulse 308 formed by interaction with the optical modulator 340 is shown. Figure 3B shows the intensity of pulse 307 as a function of time, and Figure 3C shows the intensity of pulse 308 as a function of time. (It should be noted that the time scale in Figure 3B is stretched compared to the time scale in Figure 3A). The pulse 308 includes a base part 367 and a main part 368.

The pulse 307 has an approximately Gaussian time-quantity curve (intensity versus time). The pulse 307 interacts with the modulation system 340 to form a pulse 308. The control system 150 controls the modulation system 340 to extract the specific part 365 of the pulse 307. In the example of FIG. 3B, at time t=ta, the modulation system 340 is set to transmit light, and at time t=tb, the modulation system 340 is set to block light. In other words, the optical modulation system 340 is only intended to transmit light in the portion 365 (which is the light in the pulse 307 between time ta and time tb). For example, the control system 250 can control the modulation system 340 by applying a voltage signal 347 to transmit light at time ta, so that the light passing through the electro-optical material 342 has a polarization matching with the polarization of the polarization-based optical element 346 polarization. The modulation system 340 can be controlled by removing the voltage signal 347 to stop transmitting light at time tb.

However, due to the acoustic waves in the electro-optical material 342 (or other interference, such as the unexpected movement of the polarization-based optical element 346), the optical leakage can be caused by the modulation system at the time before ta and/or at the time after the time tb. 340 transmission. In the example of FIG. 3B, the leakage light 364 is an optical leakage that occurred just before the time ta. The leakage light 364 passes through the modulation system 340 just before the portion 365.

Referring to FIG. 3C, the leakage light 364 forms the base portion 366. In the example shown, the base portion 366 appears during the window labeled 367, and the base portion 366 appears earlier in time than the rest of the pulse 308. The part of the optical pulse 308 that is not the base part 366 is called the main part 368. Both the base portion 366 and the main portion 368 are parts of the optical pulse 308, and the base portion 366 is connected to the main portion 368 in time. In other words, in the example of FIG. 3C, there is no period of no light between the base portion 366 and the main portion 368.

The base portion 366 has a time-quantity change curve (intensity that varies with time) different from that of the main portion 368. For example, the average and maximum intensity and light energy of the base portion 366 are less than the average and maximum intensity and light energy of the main portion 368. In addition, the shape of the base part 366 is different from the shape of the main part 368. In addition, the characteristics of the base portion 366 (eg, intensity, time-quantity curve, and/or duration) are different from the characteristics of the early portion of the pulse formed without any optical leakage.

The modified pulse 308 is amplified by the amplifier system 230 to form an amplified modified pulse. The amplified modified pulse includes a base portion 366 and a main portion 368, wherein each portion 366, 368 of the amplified modified pulse has an intensity greater than the corresponding portion of the modified pulse 308. In the example of FIG. 3C, the base portion 366 appears before the main portion 368 and reaches the target 221 before the main portion 368. In some implementations, the main portion 368 has sufficient intensity or energy to convert at least some of the target materials in the target 221 into plasma 196 that emits EUV light 197.

The base portion 366 does not have as much energy as the main portion 368, and may or may not have enough energy to convert the target material into plasma. However, the light in the base portion 366 can evaporate the material from the surface of the target 221, break the part of the target 221, and adjust the target 221 so that the properties (such as density, shape, and/or size) are more favorable for plasma generation. Thus, the properties of the base portion 366 allow control of the amount of EUV light generated and the characteristics of the exposure beam 191. The properties of the base portion 366 can be controlled by controlling the amount of optical leakage. The control system 250 controls the amount of optical leakage (the leakage light 364 in this example) in various ways and based on the indication 154.

The pulse 308 discussed with respect to FIGS. 3B and 3C is provided as an example of a modified optical pulse 308. The pulse 308 may have other forms. For example, the leakage light 364 may appear before the time ta, so that the base portion 366 is separated from the main portion 368. In such implementations, there are periods of no light between the base portion 366 and the main portion 368. In addition, the leakage light 364 may appear after the time tb, so that the base portion 366 appears after the main portion 368. In these implementations, the base portion 366 reaches the target 221 after the main portion 368. In some implementations, the leakage light 364 occurs before time ta and after time tb such that there is a base portion 366 on each side of the main portion 368.

In addition, the base part 366 may be separated from the main part 368 in time, and the base part 366 may include wavelengths not included in the main part 368. In some implementations, the base portion 366 is a light pulse generated by a separate light source. For example, when an optical source such as the optical source 207C (FIG. 2C) is used to form the light beam 307, the base portion 366 may be generated by a separate light source. In an implementation where the base portion 366 is generated by a separate light source, the base portion 366 interacts with the optical modulator 340, and the properties of the base 366 are adjusted by controlling the optical modulator 340 based on the indication 254.

Figure 3D shows an example of experimental data 300D. The x-axis shows the total strength of the base portion (such as the base 366 of FIG. 3C) normalized to a percentage of the total base strength required to achieve maximum conversion efficiency (CE). The conversion efficiency is an indication of the portion of the target material converted into the plasma 196. The total strength of the base 366 is the strength of the entire base 366. The maximum CE depends on various properties of the EUV light source. In the example of Figure 3D, the maximum normalized CE for the light source is represented as 100% on the y-axis. However, the maximum true (non-normalized) CE for the light source is usually less than 100%. The optimal total strength of the base is shown as 100 on the x-axis in Figure 3D.

The experimental data 300D includes data obtained on the following two different EUV sources: EUV source 1 (indicated by the X symbol) and EUV source 2 (indicated by the open circle symbol). As shown by the experimental data 300D, by changing the total strength of the base 366, the CE can be changed by about 13%. The properties of the base 366 that determine the total intensity of the base 366 (such as, for example, the maximum or average intensity or time interval) can be controlled by the modulation system 240. The amount of EUV light 197 depends on CE. Therefore, the characteristics of the exposure beam 191 and/or the EUV light 197 can be controlled by controlling the properties of the base 366.

The control system 250 can control the intensity and/or time interval of the base 366 by controlling the leakage light via the voltage signal 347, thereby controlling the properties of the light beam 207. The control system 250 controls the power supply 345 to generate a voltage signal 347 and apply the voltage signal 347 to the electrodes 344a, 344b. FIG. 4A shows plots of voltage signals 347_1 and 347_2 that vary with time. The voltage signals 347_1 and 347_2 are examples of the voltage signal 347.

The voltage signal 347_1 has an amplitude of 0 V when the modulation system 240 is in the off state. The modulation system 240 is in the off state before the time ta. At time ta, the amplitude of the voltage signal 347_1 increases to the voltage 349. The voltage 349 is a voltage greater than zero and a voltage sufficient to change the refractive index of the electro-optical material 342. At time tb, the modulation system 240 returns to the off state, and the amplitude of the voltage signal 347_2 returns to 0V. The base 366 is formed by the leakage light 364 as discussed above.

The voltage signal 347_2 includes a bias voltage 348. The bias voltage 348 is greater than zero. When the voltage signal 347_2 is used as the voltage signal 347, the bias voltage 348 is applied to the electrodes 344a, 344b, so that there is a potential difference 343 across the electro-optical material 242 when the modulation system 240 is in the off state. In some implementations, the bias voltage 348 is always applied to the electrodes 344a, 344b. The bias voltage 348 is a constant voltage (direct current or DC voltage) greater than zero and less than the voltage 349. At time ta, the modulation system 240 is in the on state, and the magnitude of the voltage signal 347_2 increases from the bias voltage 348 to the voltage 349. At time tb, the modulation system 240 is in the off state, and the magnitude of the voltage signal 347_2 returns to the bias voltage 348.

When the voltage signal 347_2 is used as the voltage signal 347, there is leakage light when the bias voltage is applied to the electro-optical material 342. Therefore, the susceptor 366 can have a longer time interval compared to the susceptor formed by the leakage light 364. In addition, when the pedestal 366 is formed by applying the bias voltage 348 to the electro-optic material 342, the pedestal 366 may appear before the main portion 368 and/or after the main portion 368. In such implementations, the modulation system 340 may include additional components that modify or reduce the time interval of the base portion 366. For example and referring also to FIG. 4B, the modified light beam 308 can interact with the acousto-optic modulator 444 to remove some of the base portion 366.

The control system 250 can also control the leakage light by manipulating the polarization element in the modulation system 240. FIG. 5 is a block diagram of the optical modulation system 540. The modulation system 540 can be used instead of the modulation system 140 (FIG. 1), the modulation system 240 (FIG. 2A), the modulation system 240_1 (FIG. 2B), or the modulation system 240_2 (FIG. 2B).

The modulation system 540 includes a first polarization element 546_1, a second polarization element 546_2, and a third polarization element 546_3. The modulation system 540 also includes a first EOM 540_1 and a second EOM 540_2. The first EOM 540_1 is between the first polarization element 546_1 and the second polarization element 546_2, and the second EOM 540_2 is between the second polarization element 546_2 and the third polarization element 546_3. In the example of FIG. 5, the first polarization element 546_1 and the third polarization element 546_3 transmit light linearly polarized in the Y direction, and the polarization element 546_2 transmits light linearly polarized in the X direction. EOM 540_1 and 540_2 modulate incident light based on the applied voltage as discussed with EOM 340 (FIG. 3A).

In the example of Figure 5, when EOM 540_1 rotates the polarization of incident light from Y direction to X direction and when EOM 540_2 rotates the polarization of incident light from X direction to Y direction, the modulation system 540 transmits light and is turned on Status. When EOM 540_2 and EOM 540_1 do not rotate the polarization of incident light, the modulation system 540 is in the off state. Therefore, when no voltage is applied to the EOM 540_1 and/or EOM 540_2 or when a voltage that is insufficient to change the polarization state of the incident light is applied to the EOM 540_1 and/or EOM 540_2, the modulation system 540 is turned off.

The optical modulation system 540 modulates the light beam 307 to produce a modified light beam 308. The modified light beam 308 may have a base portion 366. The time interval and/or intensity of the base portion 366 can be controlled by controlling the amount of leakage light. In order to change the leakage light, the control system 250 can issue a command to control the mechanical mounting table 541 coupled to the third polarization element 546_3. This command causes the mechanical mounting table 541 to rotate the third polarizing element 546_3 relative to the Y axis so that light is allowed to pass through the element 546_3, even when the EOM 540_2 does not rotate the polarization of the incident light from linear polarization along the X direction to The same is true for the state of linear polarization in the Y direction. For example, when the control system 250 has commanded the third polarization element 546_3 to rotate a few degrees from the Y axis, the EOM 540_2 can transmit light linearly polarized in the X direction. In this example, the third polarizing element transmits the leaked light. Subsequently, the voltage signal 347 is applied to the EOM 540_2, and the EOM 540_2 rotates the polarization of the incident light to be linearly polarized along the Y direction and forms the main portion 368. In this example, the main part 368 has a base based on leaking light.

Similarly, the polarization element 346 (FIG. 3A) can be placed on a mechanical mounting table and rotated based on a command from the control system 250 to control the amount and time interval of the leaked light.

FIG. 6 is a flowchart of the procedure 600. The program 600 is an example of a program for controlling the properties of the beam in the EUV light source based on the indication of the characteristics of the exposure beam. The program 600 can be executed by one or more of the electronic processors 251 of the control system 250. The program 600 is discussed about the modulation systems 240, 340, and 540. However, the procedure 600 can be executed by other control systems and can be used with other modulation systems.

Receive (610) instructions 254. The indication 254 includes information related to the characteristics of the exposure light beam 191. For example, the indication 254 may include data expressing the dose received at the portion 293 of the substrate 192. Dose is the amount of light energy received in a period of time. In these implementations, the indication 254 is generated by a sensor that senses EUV light at the substrate 192. The sensor is part of the sensor system 262. Other implementations are possible. For example, the indicator 254 may be an indicator of the amount of EUV light 197 generated at the plasma formation region 223 (FIG. 2A). In these implementations, the indication may be generated by a sensor in the vacuum chamber 211 or by a sensor in the lithography device 280 and positioned to measure EUV light 197 before interacting with the photomask 284.

Analysis (620) indicates 254. In an implementation where the indication includes a measured dose, the analysis includes comparing the measured dose to a dosage specification. The dose specification is a value or range of values specifying an acceptable dose for a portion 293 of the substrate 192. If the measured dose is lower than the specification, very little EUV light reaches the portion 293, and the electronic features may be partially formed or incomplete. If the measured dose is higher than the specification, too much EUV light reaches the portion 293, the portion is overexposed and the electronic features are again inappropriately formed. If the dose is within or equal to the specification, the correct amount of light reaches the portion 293 and the electronic features are likely to be properly and completely formed.

The control system 250 uses the information about the measured dose to control one or more attributes of the light beam 207 (630). For example, if the measured dose indicates that very little light reaches the portion 293, the control system 250 controls the modulation system 240 in such a way that more EUV light will be generated. For example, the modulation system 240 may be implemented as an EOM 340. In these implementations, the control system 250 controls the voltage signal 347 and/or manipulates the polarizing element 346 to form the base 366 to adjust the target 221 so that more EUV light 197 is generated.

If the measured dose is within or exceeds the dose specification, the control system 250 issues a command to the lithography device 280 indicating that the portion 293 should not be further exposed by the exposure beam 191. In response, the lithography device 280 moves the substrate 192 and/or the exposure beam 191 to expose different portions 293.

In addition, if the measured dose indicates that too much light reaches the portion 293, the control system 250 can control the optical modulation system 240 so that the reduced dose light reaches the next portion 293. For example, the control system 250 can reduce the total amount of EUV light reaching the substrate 192 by blocking some parts of the light beam 207, thereby reducing the amount of EUV light 197 generated throughout a time window. For example, the light beam 207 may be a pulsed light beam, and the control system 250 may activate the modulation system 240 to block or greatly reduce the intensity of every third or fourth pulse so that less EUV light 197 is generated and the dose is reduced.

Analysis instructions 254 (620) may take other forms. For example, instead of the dose, the indicator 254 may be an indicator of the measured amount of EUV light (such as the intensity of EUV light) at the entrance of the lithography device 280. In these implementations, the measured amount of EUV light is compared with the target amount or specification. If the measured amount of EUV light is lower than the specification, the control system 250 acts on the modulation system 240 by increasing the amount of EUV light 197 generated. If the measured amount of EUV light is higher than the specification, the control system 250 issues an instruction to the lithography device 280 that the exposure of the part 293 is complete. The control system 250 can also act on the modulation system 240 by reducing the amount of EUV light generated.

In the implementation where the indication 254 is an indication of the EUV light flux measurement, the control system 250 can apply the EUV light flux measurement to the model of the slit 283 and the mask 284 to estimate the dose corresponding to the EUV light flux measurement. The model of the slit 283 may be, for example, a low-pass filter, which simulates the slit 283 and therefore estimates the amount of light delivered to the substrate 191. In such implementations, the estimated dose can be compared with the dose specification.

FIG. 7A is a block diagram of the lithography system 700 including the source collector module SO. The lithography system 700 is an example of the lithography system 100. The lithography system 700 also includes: an illumination system IL configured to adjust the radiation beam B. The radiation beam B may be an EUV beam emitted from the source collector module SO. The lithography system 700 also includes a support structure MT constructed to support the patterned device MA. The support structure MT can be, for example, a photomask stage, and the patterned device MA can be, for example, a photomask or a reduction photomask. When the radiation beam B interacts with the patterned device MA, the spatial pattern associated with the patterned device MA is imparted to the radiation beam B. The support structure MT is coupled to a first positioner PM configured to position the patterned device MA. In addition, the apparatus 700 includes a substrate table WT configured to hold a substrate W, which may be, for example, a resist coated wafer. The substrate table WT is connected to a second positioner PW configured to position the substrate W. The system 700 also includes a projection system PS configured to project a patterned radiation beam E (also referred to as exposure light E or exposure beam E) onto a target portion C of the substrate W. The target portion C can be any portion of the substrate W. In the example of FIG. 7A, the substrate W includes a plurality of die D, and the target portion C includes more than one of the die D.

The illumination system IL includes optical components for guiding, shaping and/or controlling the radiation beam B and the exposure light E. The optical components may include refractive, reflective, magnetic, electromagnetic, electrostatic or any other types of optical components.

The support structure MT holds the patterned device MA in a manner that depends on the orientation of the patterned device MA, the design of the lithography system 700, and/or other conditions (such as, for example, whether the patterned device MA is held in a vacuum environment). The support structure MT may use mechanical, vacuum, electrostatic and/or other clamping techniques to hold the patterned device MA. The support structure MT may be, for example, a frame or a table, which may be fixed or movable. The support structure MT can ensure that the patterned device MA (for example) is in a desired position relative to the projection system PS.

The patterned device MA is any device that can be used to impart a pattern to the radiation beam B. The patterned device MA may be transmissive or reflective. Examples of patterned devices include photomasks, programmable mirror arrays, and programmable LCD panels. In an implementation where the patterned device MA is a photomask, the patterned device MA can be, for example, a binary photomask, an alternating phase shift photomask, or an attenuated phase shift or hybrid photomask type. In the implementation of the patterned device MA as a programmable mirror array, the patterned device MA includes a matrix configuration of mirrors, each of the mirrors can be individually tilted so that each of the mirrors can be in different directions The radiation beam B is reflected upward, and the direction does not depend on the direction in which the radiation beam B is reflected by other mirrors in the matrix. The pattern assigned to the incident light is determined by the position of each mirror in the matrix. The pattern may correspond to a specific functional layer in the device produced in the target portion C of the substrate W. For example, the pattern may correspond to electronic features that together form an integrated circuit.

The projection system PS includes optical components that guide the exposure light E to the target portion C. The optical components of the projection system PS may be refractive, reflective, magnetic, electromagnetic, electrostatic, and/or other types of optical components suitable for the exposure radiation being used or other factors such as the use of vacuum. In addition, vacuum may need to be used for EUV radiation because the gas may absorb EUV radiation. Therefore, a vacuum environment can be provided by the vacuum wall and vacuum pump.

In the example of FIGS. 7A and 7B, the device 700 is a reflective type including a reflective optical component and a reflective patterning device MA. The lithography system 700 can be of a type having two (dual stage) or more than two substrate stages (and/or two or more patterned device stages). In such a multi-stage machine, additional tables can be used in parallel, or a preliminary step can be performed on one or more tables while one or more other tables are used for exposure.

The illumination system IL receives the extreme ultraviolet radiation beam B from the source collector module SO. The EUV light source 101 (FIG. 1), 201A (FIG. 2A), 201B (FIG. 2B), and 800 (FIG. 8) are examples of the source collector module SO.

The illumination system IL may include an adjuster for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer radial extent and/or the inner radial extent (usually referred to as σ outer and σ inner respectively) of the intensity distribution in the pupil plane of the illuminator can be adjusted. In addition, the illumination system IL may include various other components, such as a faceted field mirror device and a faceted pupil mirror device. The illumination system IL can be used to adjust the radiation beam B to have the desired uniformity and intensity distribution in its cross section.

The radiation beam B interacts with the patterning device MA so that the pattern is imparted to the radiation beam B. The radiation beam B is reflected from the patterned device MA, which has a pattern imparted to the exposure light E. The exposure light E passes through the projection system PS, and the projection system PS focuses the beam onto the target portion C of the substrate W. With the second positioner PW and the second position sensor PS2, the substrate table WT can be accurately moved, for example, to position different target parts C in the path of the radiation beam B. Similarly, the first positioner PM and the other position sensor PS1 can be used to accurately position the patterned device (such as a mask) MA relative to the path of the radiation beam B. The positioning sensors PS1 and PS2 can be, for example, interferometric devices, linear encoders and/or capacitive sensors. The patterned device alignment marks M1, M2 and the substrate alignment marks P1, P2 can be used to align the patterned device MA and the substrate W.

The lithography system 700 can be used in at least one of the following modes: (1) step mode, (2) scan mode, or (3) third or other mode. In the stepping mode, when the entire pattern imparted to the radiation beam B is projected onto the target portion C at one time, the support structure MT and the substrate table WT are kept substantially stationary (ie, a single static exposure). Next, the substrate table WT is shifted in the X and/or Y direction so that different target portions C can be exposed. In the scanning mode, when the pattern imparted to the radiation beam B is projected onto the target portion C, the support structure MT and the substrate table WT are simultaneously scanned (that is, a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure MT can be determined by the magnification (reduction ratio) and image reversal characteristics of the projection system PS. In the third or other mode, when the pattern imparted to the radiation beam is projected onto the target portion C, the support structure MT is kept substantially stationary, thereby holding the programmable patterned device, and moving or scanning the substrate table WT . In this mode, a pulsed radiation source is usually used, and the programmable patterned device is updated as needed after each movement of the substrate table WT or between successive radiation pulses during scanning. This mode of operation can be easily applied to maskless lithography using programmable patterned devices, such as the type of programmable mirror array mentioned above. Combinations and/or variations of these three usage modes or completely different usage modes can also be used.

FIG. 7B shows in more detail the implementation of the lithography system 700 including the source collector module SO, the illumination system IL, and the projection system PS. The source collector module SO includes a vacuum environment. Each of the systems IL and PS also includes a vacuum environment. EUV radiation emission plasma is formed in the source collector module SO. The source collector module SO focuses the EUV radiation emitted from the plasma to the intermediate focus IF, so that the radiation beam B (760) is provided to the illumination system IL.

The radiation beam B traverses the illumination system IL. The illumination system IL includes a faceted field mirror device 22 and a faceted pupil mirror device 24 in the example of FIG. 7B. These devices form so-called "fly-eye" illuminators that are configured to provide a desired angular distribution of the radiation beam 21 at the patterned device MA and maintain the uniformity of the radiation intensity at the patterned device MA. After the reflection of the light beam B at the patterned device MA, an exposure light E (patterned light beam B) is formed, and the exposure light E (26) is imaged onto the substrate W by the projection system PS via the reflective elements 28 and 30. In addition, the exposure light E interacts with the slit that shapes the exposure light E, so that the exposure light E has a rectangular cross-section in a plane perpendicular to the propagation direction. In order to expose the target portion C on the substrate W, the source collector module SO generates a radiation pulse to form a radiation beam B, while the substrate table WT and the patterned device table MT perform synchronous movement to scan the patterned device MA through the rectangular exposure light E The pattern.

Each system IL and PS is configured in its own vacuum or near-vacuum environment, which is defined by the enclosure structure. More elements than shown can generally be present in the illumination system IL and the projection system PS. In addition, there may be more mirrors than shown. For example, in addition to the reflective elements shown in FIG. 7B, there may also be one to six additional reflective elements in the illumination system IL and/or the projection system PS.

Many additional components for the overall operation of the source collector module and the lithography system 700 are present in a typical device, but are not described here. These components include arrangements for reducing or mitigating the effects of pollution in the enclosed vacuum, for example, to prevent deposits of fuel materials from damaging or impairing the performance of the collector 3 and other optical components. Other features that exist but are not described in detail are all the sensors, controllers, and actuators involved in controlling the various components and subsystems of the lithography system 700.

Referring to Fig. 8, the implementation of LPP EUV light source 800 is shown. The light source 800 can be used as the source collector module SO in the lithography system 700. In addition, the optical source 104, the optical source 204 (FIG. 2A) and the optical source 204B (FIG. 2B) of FIG. 1 can be part of the driving laser 815.

The LPP EUV light source 800 is formed by irradiating the target mixture 814 at the plasma formation area 805 with an amplified light beam 810 that travels along a beam path toward the target mixture 814. The target material discussed in relation to FIG. 1 and the target in the stream 222 discussed in relation to FIGS. 2A and 2B may be or include the target mixture 814. The plasma formation region 805 is located in the interior 807 of the vacuum chamber 830. When the amplified light beam 810 hits the target mixture 814, the target material in the target mixture 814 is converted into a plasma state of elements with emission lines in the EUV range. The generated plasma has certain characteristics that depend on the composition of the target material in the target mixture 814. These characteristics may include the wavelength of EUV light generated by the plasma, and the type and amount of debris released from the plasma.

The light source 800 includes a driving laser system 815 that generates an amplified light beam 810 due to population inversion in one or more of the gain media of the laser system 815. The light source 800 includes a beam delivery system between the laser system 815 and the plasma forming area 805, and the beam delivery system includes a beam delivery system 820 and a focusing assembly 822. The beam delivery system 820 receives the amplified light beam 810 from the laser system 815, and turns and modifies the amplified light beam 810 as necessary and outputs the amplified light beam 810 to the focusing assembly 822. The focusing assembly 822 receives the amplified light beam 810 and focuses the light beam 810 to the plasma formation area 805.

In some implementations, the laser system 815 may include one or more optical amplifiers, lasers, and/or lamps for providing one or more main pulses and in some cases one or more pre-pulses. Each optical amplifier includes a gain medium capable of optically amplifying a desired wavelength with high gain, an excitation source, and internal optics. The optical amplifier may or may not have a laser mirror or other feedback device forming a laser cavity. Therefore, the laser system 815 will generate an amplified light beam 810 due to population inversion in the gain medium of the laser amplifier even in the absence of a laser cavity. In addition, the laser system 815 can generate the amplified beam 810 as a coherent laser beam in the presence of a laser cavity to provide sufficient feedback to the laser system 815. The term "amplified light beam" encompasses one or more of the following: light from laser system 815 that is only amplified but not necessarily coherent laser oscillation, and light from laser system 815 that is amplified and also coherent laser Shoot oscillating light.

The optical amplifier in the laser system 815 may include a filling gas (including CO ₂ ) as a gain medium, and may have a gain greater than or equal to 800 times to amplify the wavelength between about 9100 nm and about 11000 nm, and especially at about 10600 nm Of light. Suitable for use in laser amplifiers and laser system 815 may include a pulse of laser devices, for example, pulsed CO ₂ laser gas discharge device, the pulsed gas discharge CO ₂ laser device, for example, the use of a relatively high power ( For example, 10 kW or higher) and high pulse repetition rate (for example, 40 kHz or greater than 40 kHz) operating DC or RF excitation produces radiation at about 9300 nm or about 10600 nm. The pulse repetition rate can be, for example, 50 kHz. The optical amplifier in the laser system 815 may also include a cooling system, such as water, which can be used when the laser system 815 is operated at a higher power.

The light source 800 includes a collector mirror 835 having an aperture 840 to allow the amplified light beam 810 to pass through and reach the plasma formation region 805. The collector mirror 835 can be, for example, an ellipsoidal mirror with a primary focus at the plasma formation region 805 and a secondary focus (also called an intermediate focus) at the middle part 845, wherein EUV light can be output from the light source 800 and can be The EUV light is input to, for example, an integrated circuit lithography tool (not shown in the figure). The light source 800 may also include an open-ended hollow cone-shaped shield 850 (such as a gas cone), which tapers from the collector mirror 835 toward the plasma formation area 805 to reduce access to the focusing assembly 822 and/or beam delivery The amount of debris generated by the plasma of the system 820, while allowing the amplified light beam 810 to reach the plasma forming area 805. For this purpose, an air flow can be provided in the shield, and the air flow is guided toward the plasma formation area 805.

The light source 800 may also include a main control controller 855 that is connected to the droplet position detection feedback system 856, the laser control system 857, and the beam control system 858. The light source 800 may include one or more targets or droplet imagers 860 that provide an output indicating the position of the droplet, for example, relative to the plasma forming region 805 and provide this output to the small A droplet position detection and feedback system 856, which can calculate droplet position and trajectory, for example, from which droplet position and trajectory can calculate droplet position error on a drop-by-drop basis or on an average basis. The droplet position detection feedback system 856 therefore provides the droplet position error as an input to the main control controller 855. The main control controller 855 can therefore provide, for example, laser position, direction, and timing correction signals to the laser control system 857 that can be used, for example, to control the laser timing circuit and/or to the beam control system 858 to control the position of the amplified beam And the shaping of the beam delivery system 820 to change the position and/or power of the focal spot of the beam in the chamber 830.

The supply system 825 includes a target material delivery control system 826 that is operable to modify the release point of the droplet released by the target material supply device 827 in response to a signal from, for example, the main control controller 855 to correct the arrival The error in the droplet of the desired plasma formation area 805.

In addition, the light source 800 may include light source detectors 865 and 870. The light source detectors measure one or more EUV light parameters, including but not limited to pulse energy, energy distribution that varies according to wavelength, and energy within a specific wavelength band. Energy, energy outside a specific wavelength band, and the angular distribution of EUV intensity and/or average power. The light source detector 865 generates a feedback signal for the main control controller 855 to use. The feedback signal may, for example, indicate the error of parameters such as the timing and focus of the laser pulse to appropriately intercept the droplet at the appropriate place and time for effective and efficient EUV light generation.

The light source 800 may also include a guide laser 875, which can be used to align each section of the light source 800 or assist in steering the amplified light beam 810 to the plasma formation region 705. In combination with the guide laser 875, the light source 800 includes a metrology system 824 that is placed in the focusing assembly 822 to sample a portion of the light from the guide laser 875 and the amplified beam 810. In other implementations, the metrology system 824 is placed in the beam delivery system 820. The metrology system 824 may include an optical element that samples or redirects a subset of light. The optical element is made of any material that can withstand the power of the guided laser beam and the amplified beam 810. The beam analysis system is formed by the metrology system 824 and the main control controller 855. This is because the main control controller 855 analyzes the sampled light from the guide laser 875 and uses this information to adjust the focus assembly 822 via the beam control system 858 The components.

Therefore, in summary, the light source 800 generates an amplified light beam 810, which is guided along the beam path to irradiate the target mixture 814 at the plasma formation region 805 to convert the target material in the mixture 814 into emission Plasma of light in the EUV range. The amplified light beam 810 operates at a specific wavelength determined based on the design and properties of the laser system 815 (which is also referred to as the driving laser wavelength). In addition, when the target material provides sufficient feedback to the laser system 815 to generate coherent laser light or in the case that the driving laser system 815 includes appropriate optical feedback to form a laser cavity, the amplified beam 810 can be a laser beam. Shot beam.

Other aspects of the present invention are explained in the following numbered items. 1. A device used in an extreme ultraviolet (EUV) lithography system, which includes: An optical modulation system comprising at least one optical element configured to be placed on a beam path between the optical modulation system and a plasma formation region, the plasma formation region passing Configured to receive target materials emitting EUV light in a plasma state; and A control system configured to be coupled to the optical modulation system and receive a signal including an indication of a characteristic of exposure light irradiated on a wafer in a scanning system of the lithography system ,among them The control system is further configured to adjust the optical modulation system based on the indication of the characteristic of the exposure light to thereby control a property of a first part of a light beam based on the characteristic of the exposure light, the light beam comprising At least the first part and the second part. 2. The device of Clause 1, which further includes a dose sensor coupled to the control system, the dose sensor is configured to: sense the exposure light at the wafer and will include the exposure The signal of the indication of the characteristic of light is provided to the control system. 3. The device as in Clause 2, wherein the dose sensor is positioned relative to the wafer in the scanning system of the lithography system. 4. The device as in Clause 1, wherein the optical modulation system is configured to generate a modified optical pulse including a base part and a main part, and The first part of the light beam includes the base part and the second part of the light beam includes the main part, so that the control system is configured to adjust the modulation system to thereby control the base based on the characteristic of the exposure light At least one attribute of the seat part. 5. The device as in item 4, wherein the at least one attribute of the base part includes a time interval, an average intensity and/or a maximum intensity. 6. The device of Clause 4, wherein the main part of the modified pulse has an energy sufficient to convert at least some of the target material into plasma that emits EUV light. 7. The device as in Clause 4, wherein the optical modulation system includes an electro-optical modulator (EOM), and at least one optical element includes an electro-optical material. 8. The device as in Clause 7, wherein the EOM includes a first electrode and a second electrode, and the electro-optic material is between the first electrode and the second electrode. 9. The device as in clause 8, wherein the control system is configured to adjust the at least one optical element including the control system configured to: adjust one of the electro-optical materials applied by the first electrode and the second electrode The amount of voltage and/or adjust a time for applying a voltage to the electro-optical material by the first electrode and the second electrode. 10. The device of clause 8, wherein the at least one optical element of the modulation system further includes at least one polarization element configured to be placed on the beam path, and the control system is configured to adjust the at least An optical element includes the control system configured to move the polarization element. 11. The device as in Clause 10, wherein the control system is configured to adjust the at least one optical element further includes the control system configured to: adjust the application of the first electrode and the second electrode to the electro-optic material A voltage amount and/or adjustment of a time for applying a voltage to the electro-optical material by the first electrode and the second electrode. 12. The device of Clause 11, wherein the optical system includes more than one EOM, and each EOM is between two polarization elements. 13. Such as the device in item 9, where: The control system is further configured to cause the first electrode and the second electrode to apply a non-zero bias voltage to the electro-optical material during a non-active period, and during an active period, the control system is Configured to cause the first electrode and the second electrode to apply a second voltage greater than the bias voltage to the electro-optical material, An amplitude of the bias voltage is based on the indication of the characteristic of the exposure light, And the attribute of the base is determined at least in part by the amplitude of the bias. 14. The device of Clause 13, wherein the at least one optical element of the optical modulation system further includes an acousto-optic modulator (AOM), and the AOM is between the optical modulation system and the plasma formation region And the AOM is configured to determine a time interval of the base. 15. The device as in Clause 1, where the beam contains multiple pulses, The first part of the light beam includes a first pulse of one of the plurality of pulses, and The second part of the light beam includes one of the second pulses of the plurality of pulses, so that the control system is configured to adjust the modulation system to thereby control the one of the plurality of pulses based on the characteristic of the exposure light At least one attribute of the first pulse. 16. The device as in Clause 15, in which all the plural pulses propagate on the beam path. 17. The device as in Clause 15, wherein the first part of the light beam and the second part of the light beam are generated by different light sources. 18. The device of clause 1, wherein the indication of a characteristic of the exposure light includes an indication of a dose of EUV light at a specific part of the wafer, and the dose of EUV light at the wafer includes A total amount of EUV light at the specific portion of the wafer in a predetermined amount of time. 19. The device of Clause 18, wherein the control system is further configured to: analyze the indication to determine whether a threshold dose of EUV light has been delivered to the specific part of the wafer, and if the threshold dose Having been delivered to the specific part of the wafer, a command is issued to cause the wafer to move relative to the EUV light so that a different part of the wafer receives the EUV light. 20. The device according to Clause 1, further comprising: a light generating module configured to generate the light beam, the light generating module comprising a gain medium and an energy source configured to excite the gain medium, And where The control system is coupled to the light generating module, The control system is further configured to: control the energy source so that the energy of one of the beams is substantially the same throughout a time window, and The control system configured to adjust the modulation system includes the control system configured to adjust the modulation system such that an energy of the first portion of the light beam is substantially the same throughout the time window. 21. An extreme ultraviolet (EUV) light source, which includes: A container configured to form a vacuum space; A target supply device configured to provide a target to a plasma generating area in the container; An optical device including one or more optical elements configured to be placed on a beam path between a light generating module and the plasma generating region; and A control system coupled to the optical device, the control system being configured to control the optical device to thereby control one or more attributes of a first part of a light beam, the light beam including at least the first part and a first part Two parts, where in operation, the container is configured to provide EUV light to a lithography device, the lithography device is configured to guide the EUV light toward a wafer, and the first part of the The control of one or more attributes is based on a characteristic of the EUV light at the wafer. 22. Such as the EUV light source of Clause 21, which further includes a light generating module including a gain medium and an energy source configured to excite the gain medium. 23. Such as the EUV light source of Clause 22, wherein the energy source includes a plurality of electrodes configured to be driven by a radio frequency (RF) power supply, and the light generating module includes a chamber containing the plurality of electrodes, and The control system controls the one or more attributes of the first part of the light beam without adjusting any attributes of the RF power source. 24. Such as the EUV light source of Clause 21, wherein the optical device includes an optical modulation system configured to generate a modified optical pulse, the modified pulse includes a base part and a main part, and the light beam The first part includes the base part and the second part of the beam includes the main part, and The control system is configured to control the optical device to thereby control one or more properties of the base portion. 25. Such as the EUV light source of Clause 21, which further includes a light generating module, and wherein the light generating module is configured to generate a pulsed light beam including a plurality of pulses, and the first part of the light beam includes the plurality of pulses One of the first pulses of the plurality of pulses, and the second part of the light beam includes one of the second pulses of the plurality of pulses, and The control system is configured to adjust the optical device to thereby control at least one attribute of the first pulse of the plurality of pulses based on the characteristic of EUV light at the wafer. 26. For the EUV light source of Clause 21, it further includes a light generating module, and wherein the light generating module includes at least a first optical source and a second optical source, and the first part of the light beam is generated by the first optical source. An optical source generates an optical pulse, and the second part of the beam is an optical pulse generated by the second optical source. 27. The EUV light source of Clause 21 further includes a dose sensor coupled to the control system, the dose sensor being configured to sense the characteristic of the EUV light at the wafer and generate An indication of the characteristic of the EUV light at the wafer. 28. An extreme ultraviolet (EUV) lithography system, which includes: A container configured to form a vacuum space; A target supply device configured to provide a target to a plasma generating area in the container; An optical device comprising one or more optical elements, the one or more optical elements are configured to be placed on a beam path between the light generating module and the plasma generating region; A lithography device configured to receive EUV light from the container and guide the EUV light toward a wafer; and A control system coupled to the optical device, the control system being configured to control the optical device to thereby control one or more properties of a first part of a light beam, the light beam including at least the first part and a second part Part, wherein in operational use, the control of the one or more attributes of the first part is based on a characteristic of the EUV light at the wafer.

21: Radiation beam 22: Faceted field mirror device 24: Faceted pupil mirror device 26: Exposure light E 28: reflective element 30: reflective element 100: extreme ultraviolet (EUV) lithography system 101: extreme ultraviolet (EUV) light source 102: gain medium 103: Energy Source 104: optical source 106: Path 107: beam 108: Modified beam 121: Goal 123: Plasma formation area 140: Modulation system 142: Optical components 150: control system 154: instructions 180: lithography device 191: Exposure beam 192: substrate 196: Plasma 197: extreme ultraviolet (EUV) light 200A: lithography system 200B: lithography system 200C: lithography system 201A: extreme ultraviolet (EUV) light source 201B: extreme ultraviolet (EUV) light source 201C: extreme ultraviolet (EUV) light source 202: gain medium 203: Energy Source 204: Optical Source 204_1: the first optical source 204_2: second optical source 204B: Optical source 204C: Optical source 204C_1: the first optical source 204C_2: second optical source 205: beam combiner 206: beam path 207: beam 207_1: First beam 207_2: Second beam 207C_1: beam/light 207C_2: beam/light 208: Modified beam 208_1: modified beam 208_2: Modified beam 208C: Modified beam 211: Vacuum chamber 213: optical components 220: Supply System 221: target 221i: initial goal 221m: modified target 222: Streaming 223: Plasma Formation Area 223_2: Initial target area 230: Optical amplifier system 240: Optical modulation system 240B: Modulation system 240_1: Modulation system 240_2: Modulation system 242: optical components 250: control system 251: Electronic Processor 252: Electronic Storage 253: Communication Interface 254: instruction or representation 260: Metrology System 262: Sensor System 264: Electronic module 280: Lithography Device 281: reflective optics 282: reflective optics 283: Gap 284: Mask 286: Enclosure 293: part 300D: Experimental data 307: beam 308: Modified beam/pulse 340: Modulation System 342: optical components/electro-optical materials 343: Electric field/potential difference (V) 344a: Electrode 344b: Electrode 345: Power 346: Polarization-based optical components 347: Voltage signal 347_1: voltage signal 347_2: Voltage signal 348: Bias voltage 349: Voltage 364: Leak Light 365: specific part of pulse 307 366: base part 367: window 368: main part 444: Sound and Light Modulator 540: optical modulation system 540_1: The first electro-optical modulator (EOM) 540_2: The second electro-optical modulator (EOM) 541: Mechanical installation table 546_1: first polarization element 546_2: second polarizing element 546_3: third polarization element 600: program 610: receive 620: analysis 630: Control one or more attributes of the beam 700: Lithography System 760: Radiation beam B 800: Laser-generated plasma (LPP) extreme ultraviolet (EUV) light source 805: Plasma Formation Area 807: internal 810: Amplified beam 814: Target Mix 815: Drive laser / drive laser system 820: beam delivery system 822: Focus assembly 824: Metrology System 825: Supply System 826: Target Material Delivery Control System 827: Target Material Supply Device 830: vacuum chamber 835: collector mirror 840: Pore 845: middle part 850: Open-ended hollow conical shield 855: Master Controller 856: Droplet position detection feedback system 857: Laser Control System 858: Beam Control System 860: Target or droplet imager 865: Light Source Detector 870: Light Source Detector 875: Guide Laser B: radiation beam C: target part IF: Intermediate focus IL: lighting system M1: Patterned device alignment mark M2: Patterned device alignment mark MA: Patterned device MT: supporting structure P1: substrate alignment mark P2: substrate alignment mark PM: the first locator PS: Projection system PS1: Position Sensor/Position Sensor PS2: second position sensor/positioning sensor PW: second locator SO: Source Collector Module ta: time tb: time W: substrate WT: substrate table

Figures 1 and 2A to 2C are block diagrams of examples of EUV lithography systems.

Figure 3A is a block diagram of an example of an optical modulation system.

Figure 3B shows an example of optical pulse.

Figure 3C is an example of a modified optical pulse.

Figure 3D is an example of experimental data.

Figure 4A is a plot of an example voltage signal that can be applied to an optical modulation system.

4B and 5 are block diagrams of examples of optical modulation systems.

Figure 6 is a flowchart of an example program for controlling the properties of the beam.

7A and 7B are block diagrams of examples of the lithography system.

Figure 8 is a block diagram of an example of an EUV light source.

191: Exposure beam

192: substrate

196: Plasma

197: extreme ultraviolet (EUV) light

200A: lithography system

201A: extreme ultraviolet (EUV) light source

202: gain medium

203: Energy Source

204: Optical Source

206: beam path

207: beam

208: Modified beam

211: Vacuum chamber

213: optical components

220: Supply System

221: target

222: Streaming

223: Plasma Formation Area

230: Optical amplifier system

240: Optical modulation system

242: optical components

250: control system

251: Electronic Processor

252: Electronic Storage

253: Communication Interface

254: instruction or representation

260: Metrology System

262: Sensor System

264: Electronic module

280: Lithography Device

281: reflective optics

282: reflective optics

283: Gap

284: Mask

286: Enclosure

293: part

Claims (28)

A device for an extreme ultraviolet (EUV) lithography system, the device includes: An optical modulation system comprising at least one optical element configured to be placed on a beam path between the optical modulation system and a plasma formation region, the plasma formation region passing Configured to receive target materials emitting EUV light in a plasma state; and A control system configured to be coupled to the optical modulation system and receive a signal including an indication of a characteristic of exposure light irradiated on a wafer in a scanning system of the lithography system ,among them The control system is further configured to adjust the optical modulation system based on the indication of the characteristic of the exposure light to thereby control a property of a first part of a light beam based on the characteristic of the exposure light, the light beam comprising At least the first part and the second part. The device of claim 1, further comprising a dose sensor coupled to the control system, the dose sensor being configured to: sense the exposure light at the wafer and will include the exposure light The signal of the indication of the characteristic is provided to the control system. The device of claim 2, wherein the dose sensor is positioned relative to the wafer in the scanning system of the lithography system. The device of claim 1, wherein the optical modulation system is configured to generate a modified optical pulse including a base portion and a main portion, and The first part of the light beam includes the base part and the second part of the light beam includes the main part, so that the control system is configured to adjust the modulation system to thereby control the base based on the characteristic of the exposure light At least one attribute of the seat part. Such as the device of claim 4, wherein the at least one attribute of the base portion includes a time interval, an average intensity and/or a maximum intensity. The device of claim 4, wherein the main portion of the modified pulse has an energy sufficient to convert at least some of the target material into plasma that emits EUV light. The device of claim 4, wherein the optical modulation system includes an electro-optical modulator (EOM), and at least one optical element includes an electro-optical material. The device of claim 7, wherein the EOM includes a first electrode and a second electrode, and the electro-optical material is interposed between the first electrode and the second electrode. The device of claim 8, wherein the control system is configured to adjust the at least one optical element includes the control system is configured to: adjust an amount of voltage applied to the electro-optical material by the first electrode and the second electrode And/or adjust a time during which a voltage is applied to the electro-optical material by the first electrode and the second electrode. The device of claim 8, wherein the at least one optical element of the modulation system further includes at least one polarization element configured to be placed on the beam path, and the control system is configured to adjust the at least one optical element The element includes the control system configured to move the polarization element. The device of claim 10, wherein the control system is configured to adjust the at least one optical element further includes the control system is configured to: adjust a voltage applied to the electro-optical material by the first electrode and the second electrode And/or adjust a time during which a voltage is applied to the electro-optical material by the first electrode and the second electrode. Such as the device of claim 11, wherein the optical system includes more than one EOM, and each EOM is between two polarization elements. Such as the device of claim 9, where: The control system is further configured to cause the first electrode and the second electrode to apply a non-zero bias voltage to the electro-optical material during a non-active period, and during an active period, the control system is Configured to cause the first electrode and the second electrode to apply a second voltage greater than the bias voltage to the electro-optical material, An amplitude of the bias voltage is based on the indication of the characteristic of the exposure light, And the attribute of the base is determined at least in part by the amplitude of the bias. The device of claim 13, wherein the at least one optical element of the optical modulation system further comprises an acousto-optic modulator (AOM), and the AOM is between the optical modulation system and the plasma formation region, And the AOM is configured to determine a time interval of the base. Such as the device of claim 1, wherein the light beam includes a plurality of pulses, The first part of the light beam includes a first pulse of one of the plurality of pulses, and The second part of the light beam includes one of the second pulses of the plurality of pulses, so that the control system is configured to adjust the modulation system to thereby control the one of the plurality of pulses based on the characteristic of the exposure light At least one attribute of the first pulse. Such as the device of claim 15, wherein all the plurality of pulses propagate on the beam path. The device of claim 15, wherein the first part of the light beam and the second part of the light beam are generated by different light sources. The device of claim 1, wherein the indication of a characteristic of the exposure light includes an indication of a dose of EUV light at a specific portion of the wafer, and the dose of EUV light at the wafer includes a A total amount of EUV light at the specific portion of the wafer for a predetermined amount of time. Such as the device of claim 18, wherein the control system is further configured to: analyze the indication to determine whether a threshold dose of EUV light has been delivered to the specific part of the wafer, and if the threshold dose has been To deliver to the specific part of the wafer, a command is issued to cause the wafer to move relative to the EUV light so that a different part of the wafer receives the EUV light. The device of claim 1, further comprising: a light generating module configured to generate the light beam, the light generating module comprising a gain medium and an energy source configured to excite the gain medium, and wherein The control system is coupled to the light generating module, The control system is further configured to: control the energy source so that the energy of one of the beams is substantially the same throughout a time window, and The control system configured to adjust the modulation system includes the control system configured to adjust the modulation system such that an energy of the first portion of the light beam is substantially the same throughout the time window. An extreme ultraviolet (EUV) light source, which includes: A container configured to form a vacuum space; A target supply device configured to provide a target to a plasma generating area in the container; An optical device including one or more optical elements configured to be placed on a beam path between a light generating module and the plasma generating region; and A control system coupled to the optical device, the control system being configured to control the optical device to thereby control one or more attributes of a first part of a light beam, the light beam including at least the first part and a first part Two parts, where in operation, the container is configured to provide EUV light to a lithography device, the lithography device is configured to guide the EUV light toward a wafer, and the first part of the The control of one or more attributes is based on a characteristic of the EUV light at the wafer. For example, the EUV light source of claim 21, which further includes a light generating module including a gain medium and an energy source configured to excite the gain medium. For example, the EUV light source of claim 22, wherein the energy source includes a plurality of electrodes configured to be driven by a radio frequency (RF) power supply, and the light generating module includes a chamber that accommodates the plurality of electrodes, and the control The system controls the one or more attributes of the first part of the light beam without adjusting any attributes of the RF power source. Such as the EUV light source of claim 21, wherein the optical device includes an optical modulation system configured to generate a modified optical pulse, the modified pulse including a base part and a main part, and the first part of the light beam Includes the base portion and the second portion of the beam includes the main portion, and The control system is configured to control the optical device to thereby control one or more properties of the base portion. For example, the EUV light source of claim 21, which further includes a light generating module, and wherein the light generating module is configured to generate a pulsed beam including a plurality of pulses, and the first part of the beam includes the plurality of pulses One of the first pulse, and the second part of the light beam includes one of the second pulses of the plurality of pulses, and The control system is configured to adjust the optical device to thereby control at least one attribute of the first pulse of the plurality of pulses based on the characteristic of EUV light at the wafer. For example, the EUV light source of claim 21, which further includes a light generating module, and wherein the light generating module includes at least a first optical source and a second optical source, and the first part of the light beam is generated by the first optical source. The source generates an optical pulse, and the second part of the beam is an optical pulse generated by the second optical source. Such as the EUV light source of claim 21, which further includes a dose sensor coupled to the control system, the dose sensor being configured to sense the characteristic of the EUV light at the wafer and generate the crystal An indication of the characteristic of the EUV light at the circle. An extreme ultraviolet (EUV) lithography system, which includes: A container configured to form a vacuum space; A target supply device configured to provide a target to a plasma generating area in the container; An optical device comprising one or more optical elements, the one or more optical elements are configured to be placed on a beam path between the light generating module and the plasma generating region; A lithography device configured to receive EUV light from the container and guide the EUV light toward a wafer; and A control system coupled to the optical device, the control system being configured to control the optical device to thereby control one or more properties of a first part of a light beam, the light beam including at least the first part and a second part Part, wherein in operational use, the control of the one or more attributes of the first part is based on a characteristic of the EUV light at the wafer.

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