TW202032278A - Monitoring light emissions - Google Patents

Abstract

Provided is a system that includes a vacuum chamber with an interior region that is configured to receive a target and a light beam. The target material emits extreme ultraviolet (EUV) light when in a plasma state. The system also includes a detection system configured to image the interior region by detecting light emission from atoms, ions, or molecules in the interior region and producing a representation of a spatial distribution of the light emission in the interior region. A control system is coupled to the detection system. The control system is configured to analyze the representation of the spatial distribution to determine a spatial distribution of the light emission from atoms, ions, or molecules in the interior region, and determine whether to adjust a property of the light beam and/or a property of the vacuum chamber based on the spatial distribution of the light emission.

Description

Monitor light emission

The present invention relates to monitoring light emission. The light emission can be the emission of light that occurs in a vacuum chamber of an extreme ultraviolet (EUV) light source.

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 processes to produce 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, streams, etc. Or the target material in the form of clusters to generate the required plasma. For this process, 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 a general aspect, a system includes: a vacuum chamber that includes an internal region configured to receive a target and a beam of light, the target includes emitting extreme ultraviolet when in a plasma state (EUV) The target material of light; a detection system configured to image the inner zone, the detection system being configured to detect light emission from atoms, ions or molecules in the inner zone and in the A representation of the spatial distribution of the light emission is generated in the internal area; and a control system coupled to the detection system, the control system being configured to: analyze the representation of the spatial distribution of the light emission to determine A spatial distribution of the light emission from atoms, ions or molecules in the inner region; and determining whether to adjust at least one property of the light beam and/or at least one property of the vacuum chamber based on the spatial distribution of the light emission.

Implementations can include one or more of the following features. The light emission may include fluorescence. Fluorescence may include laser-induced fluorescence. The control system is configured to analyze the expression and may also include the control system configured to compare the spatial distribution of the fluorescent light in at least two internal regions at different times to estimate the velocity of the ions in the internal region, and compare the estimated velocity with The speed specification, and the control system can be configured to determine whether to adjust the pressure of the gas based on the comparison of the estimated speed and the speed specification.

The system may also include one or more spectral filters configured to be positioned relative to the detection system, the spectral filters being configured to allow only some wavelengths to reach the detection system. Each of the one or more spectral filters can be configured to transmit light having a wavelength in one of the plurality of emission lines of the target material. In some implementations, at least one of the one or more spectral filters is configured to transmit wavelengths in the visible range. The vacuum chamber may be further configured to contain a gas in the inner region, and the spectral filter may be configured to transmit light having a wavelength at the emission line of the gas.

The control system can be configured to receive multiple representations of the internal area, each of the multiple representations can be associated with a different time, and the control system configured to analyze the representation of the internal area can include the control system being configured To analyze each of the plurality of representations to determine the spatial distribution of the light emission in the inner region of each of each at different times. The light emission in the inner zone can be caused by an energy event in the inner zone, and the different times are all times that occur after the energy event. The energy event can include the interaction between the light beam and the target, and the light emission can be the emission from: (a) the target material; (b) the plasma formed by the interaction between the light beam and the target material; and /Or (c) Fragments formed by the interaction between the beam and the target.

The control system can be configured to receive an extended exposure representation of the inner zone, the extended exposure representation of the inner zone including the average of the spatial distribution of emissions in the inner zone within a time period. The vacuum chamber can be further configured to contain a gas in the inner zone, the energy event can be an interaction that adds energy to the gas, and the light emission can be an emission from the gas. The interaction of adding energy to the gas may include (a) the interaction between the light beam and the gas; (b) the interaction between the gas and the plasma formed by the interaction between the light beam and the target; and/or (c ) The interaction between ions and gases.

The control system being configured to analyze the representation to determine the spatial distribution of light emission in the inner region may include the control system being configured to estimate the shape and/or spatial distribution of the intensity of the light emission.

In some implementations, the system also includes: a first spectral filter configured to transmit light having a wavelength in a first wavelength band; and a second spectral filter configured To transmit light having a wavelength in a second wavelength band, and the control system is configured to analyze the representation may include: the control system is configured to estimate the amount of light emission in the first wavelength band and estimate the The amount of light emission in the second wavelength band, and the control system may be further configured to be based on comparing the estimated amount of light emission at the first wavelength band with the amount of light emission at the second wavelength band. The estimated amount is used to estimate the ionization fraction of the target material. The control system can determine whether to adjust at least one property of the light beam based on the estimated ionization fraction. The control system can determine whether to adjust the direction of the beam based on the estimated ionization fraction.

The light beam may include a main pulsed light beam having energy sufficient to convert at least some of the target materials into plasma that emits EUV light.

The beam may include a pre-pulse beam.

The representation of the spatial distribution may include the representation of a two-dimensional representation.

The light beam may include a pulsed light beam, and the control system configured to adjust at least one property of the light beam may include the control system configured to adjust at least one property of a pulse that occurs later in the pulsed light beam.

In another general aspect, an EUV light source includes a vacuum chamber configured to perform the following operations: containing a gas in an inner region and receiving a target and a beam, the target included in a plasma state A target material that emits extreme ultraviolet (EUV) light; a monitor that includes at least one sensor configured to detect emission from the gas in the inner region and generate the Detect and emit an indication; and a control system coupled to the monitor, the control system is configured to: analyze the indication of the detected emission; and determine whether to adjust at least one property of the beam based on the analysis And/or at least one property of the vacuum chamber.

Implementations can include one or more of the following features. The monitor may include a detection system configured to image a portion of the inner region and produce a representation of the spatial distribution of the detected emissions in the portion. The control system can be configured to receive a plurality of representations over a period of time, each representation indicating a spatial distribution of the detected transmissions in the portion of the time period at a different time, and the control system can be grouped The state is used to determine whether to adjust at least one property of the light beam and/or at least one property of the vacuum chamber based on two or more of the plurality of representations.

The gas may include hydrogen, and the detected emission may include H alpha (H-α) and/or H beta (H-β) emission from hydrogen.

The EUV light source may also include: a first spectral filter configured to transmit a first wavelength band; and a second spectral filter configured to transmit a second wavelength band, wherein In use, the first spectral filter and the second spectral filter may be between the part and the detection system; and the control system configured to analyze the detected emissions may include the control system It is configured to compare a representation of the emission transmitted by the first spectral filter with one representation of the emission transmitted by the second spectral filter; and whether to adjust at least one property of the light beam and based on the comparison /Or determination of at least one property of the vacuum chamber.

The EUV light source may also include a pressure controller coupled to the inside of the vacuum chamber, the pressure controller is configured to change a pressure of the gas in the inside of the vacuum chamber, and the control system may Coupled to the pressure controller.

In another general aspect, a method of controlling an EUV light source includes: providing a target to a target zone in a vacuum chamber, the vacuum chamber containing a gas in an internal zone; and causing a beam to interact with the target An interaction between the targets in the region; detecting light emission from atoms, ions, and/or molecules in the inner region of the vacuum chamber, the light emission being an energy event in the vacuum chamber In a response of, the energy event includes an event of adding energy to the target and/or the gas; analyzing the detected light emission to determine a spatial distribution of the light emission in the inner region; and determining whether to adjust based on the analysis A property of the light beam and/or the gas.

Implementations of any of the technologies described above may include EUV light sources, systems, methods, processes, devices, or devices. The details of one or more implementations are set forth in the following drawings and description. Other features will be obvious from the description and drawings and from the scope of the patent application.

A technique for controlling an extreme ultraviolet (EUV) lithography system and/or an EUV source based on the analysis of the emission of light occurring in the vacuum chamber of the EUV source is disclosed.

Referring to FIG. 1A, a block diagram of an extreme ultraviolet (EUV) light source 100 is shown. The EUV light source 100 includes a sensor system 130 and a control system 150. The sensor system 130 monitors the emission of light occurring inside the vacuum chamber 109 and provides information about the emission to the control system 150. The emissions are analyzed by the control system 150, which is configured to adjust one or more components of the EUV light source 100 based on the analysis of the emissions. The emissions may be emissions from target materials and/or fragments 195 in the plasma 196, gas 122, target 121p. Monitoring the emission in the vacuum chamber 109 allows the determination and control of various parameters of the EUV source 100 that affect the efficiency of the EUV source. For example, the information from the sensor system 130 can be used to determine the portion or fraction of the target material (or fuel) ionized by the plasma generation event and/or to determine the deposition in the gas 122 in the vacuum chamber 109 The amount of energy. Knowledge of such parameters allows the control system 150 to improve the performance of the EUV light source 100.

The monitored emission is light emitted from one or more substances in the vacuum chamber 109. These substances include or are atoms, molecules and/or ions. The emission can be any kind of emission involving luminescence from a substance. For example, the emission may be optical emission due to excitation of atoms by a high-temperature source. In another example, the emissions can be fluorescence from atoms, molecules, or ions. Fluorescence is the emission of light by substances that have absorbed light or other electromagnetic radiation.

In addition, the emission can be laser-induced fluorescence. Laser-induced fluorescence is a process by which atoms, ions, or molecules absorb laser light and the electrons of the substance are excited to a higher energy level. After excitation, the electron decays to a lower energy level and the atom, ion, or molecule emits light. The emitted light is laser-induced fluorescence. The laser-induced fluorescence may be generated by irradiating the substance with the light beam 106 (which may be a laser) and/or by irradiating the substance with the laser beam 115 generated by the detection laser 108. Any laser suitable for exciting the substance in the manner of interest can be used as the detection laser 108. For example, the detection laser 108 may be a laser that can be tuned to produce one of several different wavelengths (such as an optical parametric oscillator or other types of tunable lasers).

The wavelength of a specific emission is determined by the nature of the substance and the amount of energy used to excite the substance. In addition, certain substances can produce more than one wavelength of emission. For example, hydrogen emits light with a wavelength of 658.28 nanometers (nm) when hydrogen electrons transition from the third lowest energy level to the second lowest energy level. This emission is referred to as H alpha (H-α) emission. However, hydrogen also emits light of other wavelengths. For example, hydrogen emits light with a wavelength of 486.14 nm when hydrogen electrons transition from the fourth lowest energy level to the second lowest energy level. This emission is called H Beta (H-β) emission. Hydrogen also has other emission lines. The wavelength emitted by hydrogen depends on the amount of excitation energy, which determines the energy level to which the electron is excited from the ground state. Similarly, other substances that may exist in the vacuum chamber 109 emit light of specific wavelengths depending on their respective physical properties and the energy by which the substances are excited.

By analyzing these emissions, the control system 150 can monitor the conditions in the vacuum chamber 109 and adjust the environment in the vacuum chamber 109 accordingly. In detail, the control system 150 is configured to analyze and adjust one or more properties of subsequent (later occurring) pulses of the light beam 106 and/or one or more properties of the vacuum chamber 109 based on the monitored emission. The properties of the subsequent pulses of the beam 106 that can be adjusted include, for example, the size (for example, the beam waist at the plasma formation site 123), the average and/or maximum energy, the time duration, and/or the relative value of the plasma formation site 123. position. The adjustable properties of the vacuum chamber 109 include, for example, the pressure of the gas 122, the temperature of the gas 122, the flow rate of the gas 122, the flow direction of the gas 122, the size of the target 121p, and/or the target interval in the stream of the target 121 .

The various components of EUV source 100 are discussed in more detail before the control system 150 is discussed.

The EUV source 100 also includes a target supply system 110 that transmits a stream 121 of targets. The target supply system 110 includes a target forming device 117 that defines an aperture 119 fluidly coupled to the reservoir 118. In operational use, the target material is in a flowable state (for example, the target material is melted and at a temperature higher than its melting point) and the reservoir 118 is pressurized to pressure P. The pressure P is greater than the pressure in the vacuum chamber 109. Therefore, in operation and use, the target material flows through the hole 119 and enters the vacuum chamber 109 to form the target stream 121. In the example of FIG. 1A, the stream 121 of targets generally travels in the x direction from the hole 119 to the plasma formation site 123, wherein the target 121p (which is one of the targets in the stream 121) is depicted in FIG. 1A The time is at the plasma formation site 123.

The target in the target stream 121 may be a droplet of target material. The target material can be any material that emits EUV light when in the plasma state. For example, the target material may include water, tin, lithium, and/or xenon. The target material may be a target mixture including target substances and impurities (such as non-target particles). The target substance is a substance that has an emission line in the EUV range when in a plasma state. The target substance can be, for example, a droplet of a liquid or molten metal, a part of a liquid stream, solid particles or clusters, a solid particle contained in a droplet, a foam of the target material, or a part contained in a liquid stream Solid particles. The target substance can be, for example, water, tin, lithium, xenon, or any material that has an emission spectrum in the EUV range when converted into a plasma state. For example, the target substance may be elemental tin, which can be used as pure tin (of Sn); as tin compounds, _{e.g., SnBr 4, SnBr 2, SnH} 4; as a tin alloy, for example, tin - gallium alloy, tin -Indium alloy, tin-indium-gallium alloy, or any combination of these alloys. In addition, in the absence of impurities, the target material only includes the target substance.

During the operation of the EUV source 100, the plasma 196 is formed by the interaction of the light beam 106 with the target 121p at the plasma formation site 123. Plasma includes fine or small particles collectively called plasma particles. The plasma particles may be, for example, vaporized, atomized, and/or ionized particles of fuel, and the monitored emission may include emission from any of these substances. The interaction of the light beam with the target material (where the light beam has sufficient energy to convert at least some of the target material into plasma) is called a plasma generation event. Each plasma generation event also generally generates fragments (eg, fragments or pieces of target material not converted into plasma 196) and the monitored emission may include emission from the fragments. Therefore, during operation of the EUV source 100, the plasma 196 and debris 195 are present in the chamber 109 after the plasma generation event.

The EUV source 100 also includes a light generating module 105 which generates a light beam 106. The light generating module 105 can be, for example, a carbon dioxide (CO ₂ ) laser or a solid-state laser. The light generating module 105 may include various other components not shown in FIG. 1A, such as a preamplifier, a power amplifier, optical elements for guiding light (such as a mirror), and a beam combiner. In some embodiments, the light generating module 105 includes more than one optical source and may include more than one laser and may include different types of lasers. Figure 2 shows an example of a light generating module 205 that includes more than one optical source.

The light beam 106 can be a pulse train each of which is separated from the pulse closest in time. FIG. 1B shows an example of the time curve (optical power over time) of the pulse 104 in the column. The pulse 104 is an example of one of the pulses that can be part of the light beam 106. The pulse 104 has a peak power 103 and a finite time duration 102. In the example of FIG. 1B, the pulse duration 102 is the time during which the pulse 104 has non-zero power. The time for the pulse 104 to increase from zero to the peak power 103 is the rise time of the pulse. In other implementations, the pulse duration 102 and/or rise time may be based on other measures. For example, the pulse duration 102 may be less than the time during which the pulse 104 has a non-zero power (such as the full width at half maximum (FWHM) of the pulse 104). Similarly, the rise time can be measured between two values different from zero optical power and peak optical power 103.

In the example shown, the power of pulse 104 monotonically increases from zero power to peak power 103 and decreases monotonically from peak power 103 to zero. Other time curves are possible. For example, the power of the pulse can increase non-monotonically from zero to the peak power. The pulse may have more than one peak energy point. In addition, the pulses in the pulse train constituting the light beam 106 may have different time curves.

The light beam 106 is guided on the optical path 107 to the vacuum chamber 109 by the light beam delivery system 111 including one or more optical components 112. The optical component 112 may include any component capable of interacting with the light beam 106. The component 112 may also include devices capable of forming and/or shaping the pulse 104. For example, the optical component 112 may include passive optical devices (such as mirrors, lenses, and/or mirrors), and any associated mechanical mount devices and/or electronic drivers. These components can steer and/or focus the light beam 106. Additionally, the optical component 112 may include components that modify one or more of the characteristics of the light beam 106. For example, the optical component 112 may include an active optical element capable of changing the time profile of the light beam 106 to form the pulse 104, such as an acousto-optic modulator and/or an electro-optic modulator.

The pulse 104 leaves the beam delivery system 111 and enters the vacuum chamber 109. The pulse 104 passes through the aperture 113 of the optical element 114 to reach the plasma formation site 123. The interaction between the pulse 104 and the target material in the target 121p produces a plasma 196 that emits light 197. The light 197 includes light having a wavelength corresponding to the emission line of the target material in the target 121p.

The light 197 includes EUV light 198 and out-of-band light. Out-of-band light is light with a wavelength not in the EUV light range. For example, the target material may include tin. In these embodiments, the light 197 includes EUV light 198 and also includes out-of-band light, such as deep ultraviolet (DUV) light, visible light, near infrared (NIR) light, intermediate wavelength infrared (MWIR) light, and/or long wavelength Infrared (LWIR) light. EUV light 198 may include light having a wavelength of, for example, 5 nanometers (nm), 5 nm to 20 nm, 10 nm to 120 nm, or less than 50 nm. DUV light may include light having a wavelength between about 120 nm and 300 nm, visible light may include light having a wavelength between about 390 nm and 750 nm, and NIR light may include light having a wavelength between about 750 nm and 2500 nm. The MWIR light may have a wavelength between about 3000 nm and 5000 nm, and the LWIR light may have a wavelength between about 8000 nm and 12000 nm.

The optical element 114 has a reflective surface 116 that is positioned to receive at least some of the light 197. The reflective surface 116 has a coating of a nominal amount that reflects the EUV light 198 but not the out-of-band component of the light 197 or only the out-of-band component of the light 197. In this way, the reflective surface 116 only guides EUV light 198 to the lithography device 199.

The EUV source 100 also includes a gas management system 140 that supplies gas 122 to the vacuum chamber 109. The gas 122 may be, for example, hydrogen or oxygen. The gas management system 140 may include pumps, valves, and other components for gas management. The gas management system 140 is configured to control various properties of the gas 122 supplied to the vacuum chamber, such as temperature, pressure, and/or flow rate. For example, the gas management system 140 may be sufficient to supply gas 122 at a flow rate of moving debris (such as debris 195) in a controlled manner and/or control the temperature and/or pressure of gas 122 to affect the state of plasma generation.

The EUV light source 100 also includes a sensor system 130, which provides a signal 157 including data related to the monitored emission to the control system 150. As mentioned above, the monitored emissions may include emissions from plasma 196, emissions from gas 122, and/or emissions from debris 195. The sensor system 130 includes a sensor module 134 including one or more sensors 135. The sensor 135 is any detector or sensor capable of detecting or sensing light having a wavelength of interest emitted. Therefore, in the example of FIG. 1A, the sensor 135 can be a sensor capable of detecting emission from the plasma 196, a sensor capable of detecting one or more wavelengths that can be emitted from the gas 122, and/ Or a sensor capable of sensing the wavelength of light emitted from the fragment 195.

In some implementations, the sensor 135 can generate data that includes spatial information about the emission. For example, the sensor 135 may be a two-dimensional array of sensors, where each sensor is configured to sense light emitted from a specific portion of the vacuum chamber 109. Each sensor is fixed and has a known location relative to the part of the vacuum chamber 109 monitored by the sensor, so the relative location of the sensed emission can also be determined. In these embodiments, the spatial information shows how the emissions are distributed in the vacuum chamber 109. The data from the sensor 135 can be used to form a two-dimensional spatial representation (such as an image) of the vacuum chamber 109 (part of the vacuum chamber 109), where the image shows the relative location of the monitored emission within the vacuum chamber 109.

In addition, the sensor 135 may be able to generate many two-dimensional spatial representations of the monitored emission in the vacuum chamber 109 over a period of time. For example, the sensor 135 may be a video sensor that captures frames (images) collected at a frame rate determined by the video sensor. In these embodiments, each frame is a representation of the emission in the vacuum chamber 109 at different times. In another example, the sensor is a camera with an exposure mechanism that allows the sensor to sense emission within a limited period of time. In these embodiments, the data generated by the sensor 135 represents the time average of the emission in the vacuum chamber 109. The sensor module 134 may include more than one sensor. In these embodiments, the sensor 135 is located at a different location relative to a specific area of the vacuum chamber 109, so that the data generated by the sensor 135 can be used to generate a three-dimensional representation of the monitored emission.

In addition, the sensor system 130 may also include a spectral filter module 137. The spectral filter module 137 includes one or more spectral filters 136. The spectral filter 136 allows controlling which specific wavelength or wavelengths are sensed by the sensor 135. In this way, the specific emission can be separated from the total emission in the vacuum chamber so that only the emission of interest is monitored. When included in the sensor system 130, the spectral filter 136 is positioned on the optical path between the sensor 135 and the monitored portion inside the vacuum chamber 109.

The spectral filter 136 is any filter capable of allowing only some wavelengths or specific wavelengths to reach the sensor 135 while substantially preventing any other wavelengths from reaching the sensor 135. The spectral filter 136 may be, for example, a spectral filter that allows only visible light to reach the sensor 135, or a spectral filter that only allows specific wavelengths in the visible spectrum to reach the sensor 135. The spectral filter 136 may separate wavelengths based on transmission, reflection, and/or absorption. For example, the spectral filter 136 can be a multilayer dielectric stack that transmits wavelengths in the wavelength band while reflecting or absorbing all other wavelengths. In another example, the spectral filter 136 may be a dichroic mirror or grating that reflects different wavelengths in different directions.

The spectral filter module 137 may include more than one spectral filter 136. For example, in some implementations, the sensor module 134 includes more than one sensor 135, and the spectral filter module 137 includes a spectral filter for each of the sensors器136.

The EUV light source 100 also includes a control system 150 that uses information from the sensor system 130 to analyze the emission in the vacuum chamber 109. The control system 150 also provides a command signal 159 (which is generated based on information about the emission in the vacuum chamber 109) to the light generating module 105, the target supply system 110, the gas management system 140, and/or the beam delivery system 111.

The control system 150 includes an analysis module 152. The analysis module 152 analyzes the information from the sensor system 130 and determines whether to adjust the light beam 106 and/or the vacuum chamber 109 based on the analysis. Refer to FIG. 3 to further discuss the operation of the control system 150 and the analysis module 152. In the example of FIG. 1A, the electronic processor 154, the electronic storage 156 and the I/O interface 158 are used to implement the analysis module 152 of the control system 150. The electronic processor 154 includes one or more processors suitable for executing computer programs, such as general or special-purpose microprocessors, and any type of any type of digital computer. Generally speaking, electronic processors receive commands and data from read-only memory, random access memory (RAM), or both. The electronic processor 154 can be any type of electronic processor. The electronic processor 154 executes the instructions constituting the analysis module 152.

The electronic storage 156 may be a volatile memory such as RAM, or a non-volatile memory. In some implementations, the electronic storage 156 includes non-volatile and volatile portions or components. The electronic storage 156 can store data and information used to control the operation of the system 150. For example, the electronic storage 156 can store instructions for implementing the analysis module 152 (for example, in the form of a computer program). The analysis module 152 receives information from the sensor system 130, and may also receive information from the light generating module 105, the gas management system 140, the supply system 110, and/or the beam delivery system 111.

The electronic storage 156 may also store instructions (perhaps as a computer program) which, when executed, cause the electronic processor 154 and the light generating module 105, the gas management system 140, the beam delivery system 111, the supply system 110 and/or The components in the sensor system 130 communicate. For example, the instructions may be instructions for prompting the electronic processor 154 to provide the command signal 159 generated by the analysis module 152 to the light generating module 105, the gas management system 140, the supply system 110, and/or the beam delivery system 111.

The command signal 159 is a signal that causes the light generating module 105 and/or the components in the beam delivery system 111 to act in a manner of adjusting the light beam 106 or a signal that causes the gas management system 140 to adjust the properties of the gas 122. For example, the command signal 159 may be a signal including information sufficient to prompt the valve and/or pump in the gas management system 140 to start operation, stop operation, or continue but operate in a different manner. In another example, the command signal 159 is a signal capable of adjusting the properties of the target supply system 110 that change the rate at which the target reaches the plasma formation site 123. In this example, the command signal 159 may be a signal including information sufficient to cause the target forming device 117 to vibrate at different rates so that the size and/or rate of the target reaching the plasma forming site 123 changes. In yet another example, the command signal 159 is a signal that operates on the light generating module 105 and/or the beam delivery system 111 to change the properties of the beam 106. For example, the command signal 159 may be a signal sufficient to cause the mirror in the beam delivery system 111 to move or a signal sufficient to adjust the operation of the electro-optical modulator in the beam delivery system 111.

The I/O interface 158 is for allowing one or more components of the control system 150 and arithmetic unit (operator), the light generating module 105, the light generating module 105, the lithography device 199 and/or to run on another electronic device Any kind of interface for the exchange of data and signals with automated procedures. For example, in some implementations, the analysis module 152 can be programmed by the end user to include end-user-specific analysis. In these implementations, the analysis module can be programmed via the I/O interface 158. The I/O interface 158 may include one or more of a visual display, a keyboard, and a communication interface such as a parallel port, a universal serial bus (USB) connection, and/or any type of network interface such as Ethernet. The I/O interface 158 may also allow communication via, for example, IEEE 802.11, Bluetooth, or Near Field Communication (NFC) connections without physical contact.

Referring to FIG. 2, a block diagram of EUV light source 200 is shown. The EUV light source 200 is another example of the implementation of the EUV light source. The EUV light source 200 is the same as the EUV light source 100 (FIG. 1A) except that the EUV light source 200 uses a light generating module 205 including a first optical source 208_1 emitting a first light beam 206_1 and a second optical source 208_2 emitting a second light beam 206_2 . The pulse 204_1 is the pulse of the first light beam 206_1, and the pulse 204_2 is the pulse of the second light beam 206_2. The pulse 204_2 may be referred to as the "pre-pulse" beam, and the pulse 204_1 may be referred to as the "main pulse" beam.

The EUV light source 200 includes the optical element 114, but only the aperture 113 of the optical element 114 is shown in FIG. 2 for simplicity. The pulse 204_2 propagates along the beam path 207_2, passes through the aperture 113 of the optical element 114, and is delivered to the initial target area 224 via the beam delivery system 211-2. The initial target area 224 receives the initial target 221p from the supply system 110. The initial target area 224 is displaced in the −x direction with respect to the plasma formation site 123.

The pulse 204_2 interacts with the target 221p at the initial target area 224 to adjust the target 221p and form a modified target 221m. The adjustment can enhance the ability of the target 221p to absorb the pulse 204_1. For example, although EUV luminescent plasma 196 is not generally generated at the initial target area 224, the interaction between the pulse 204_2 and the target 221p can change the shape, volume, and/or distribution of the target material in the initial target 221p. The size and/or the density gradient of the target material can be reduced along the propagation direction of the main pulse 204_1. In addition, the interaction between the pulse 204_2 and the initial target 221p can generate a pre-plasma or plasma that does not necessarily emit EUV light. The modified target 221m may be, for example, a disk-shaped distribution of target material, which has a larger range in the x-y plane than the target 221p and a smaller range along the z-axis than the target 221p. The modified target 221m is shifted to the plasma formation site 123 and irradiated by the pulse 204_1 to form the plasma 196.

In the embodiment of FIG. 2, the control system 150 is coupled to the optical source 208_2 and the beam delivery system 211_2, so that the control system 150 can be used to control the properties of the second beam 206_2 (or the subsequent or later pulses of the beam 206_2). For example, the control system 150 can adjust the pulse energy of the later pulse of the beam 206_2, the position of the later pulse of the beam 206_2 relative to the expected part of the target 221p, and/or the pulse of the beam 206_2 later Duration. In this way, the control system 150 can be used to control the adjusted parameters of the initial target 221p. The control system 150 is also coupled to the optical source 208_1 and the beam delivery system 211_1 and can be used to control the properties of the beam 206_1 (or the pulse of the beam 206_1). In addition, the control system 150 is coupled to the gas management system 140 and can adjust one or more characteristics of the gas 122.

The light sources 208_1 and 208_2 can be, for example, two lasers. For example, the light sources 208_1 and 208_2 may be two carbon dioxide (CO ₂ ) lasers. In other embodiments, the light sources 208_1 and 208_2 can be different types of lasers. For example, the optical source 208_2 may be a solid-state laser, and the optical source 208_1 may be a CO ₂ laser. In the example of FIG. 2, the first beam 206_1 and the second beam 206_2 are pulsed. The first light beam 206_1 and the second light beam 206_2 may have different wavelengths. For example, in an implementation where the light sources 208_1 and 208_2 include two CO ₂ lasers, the wavelength of the first beam 206_1 may be about 10.26 micrometers (µm) and the wavelength of the second beam 206_2 may be between 10.18 µm and 10.26 µm between. The wavelength of the second light beam 206_2 may be about 10.59 µm. In these implementations, the beams 206_1, 206_2 are generated from different lines of the CO ₂ laser, resulting in the beams 206_1, 206_2 having different wavelengths, even though the two beams are both generated from the same type of source.

The pulses 204_1 and 204_2 have different energies and may have different durations. For example, the pre-pulse 204_2 may have a duration of at least 1 ns. For example, the pre-pulse may have a duration of 1 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 to 60 mJ, a pulse duration of 20 to 70 nanoseconds (ns), and a wavelength of 1 to 10 microns (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, between 100 and 300 ps, or between 10 and 100 ps.

Each of the beam delivery systems 211_1 and 211_2 is similar to the beam delivery system 111 (FIG. 1A). In the example of FIG. 2, the first beam 206_1 and the second beam 206_2 interact with the separate beam delivery system and travel on separate optical paths. However, in other implementations, the first beam 206_1 and the second beam 206_2 may share all or part of the same optical path and may also share the same beam delivery system.

Referring to Figure 3, a flowchart of the procedure 300 is shown. The program 300 is an example of a program that can be executed by the control system 150.

The light emitted from the substance in the vacuum chamber 109 is detected (310). The emitted light is detected by the sensor 135. Substances can be atoms, ions, and/or molecules. The substance may be part of gas 122, plasma 196, and/or fragment 195. The light emitted from the substance can be fluorescence or laser-induced fluorescence. The emitted light is detected by the sensor 135. The sensor 135 generates data indicating the characteristics of the emitted light. For example, the data can indicate the intensity of the emitted light. In some embodiments, the data indicates the relative location of the emitted light in the vacuum chamber 109. In these embodiments, the data can be used to form a two-dimensional representation, such as an image. Furthermore, in some embodiments, the sensor module 134 includes more than one sensor 135. More than one sensor 135 can be positioned relative to a specific part of the vacuum chamber 109. In these implementations, the data from the sensors 135 can be used together to form a three-dimensional representation of the spatial distribution of light emission in the vacuum chamber 109 in a three-dimensional form.

In some embodiments, the sensor 135 collects data in a relatively short period (for example, 20 microseconds (µs) or less, such as a period of 10 nanoseconds (ns) or less), so that the detected emission and A single plasma generation event is associated. Such embodiments allow one or more components of EUV light source 100 or 200 to be changed on a pulse-by-pulse basis. In addition, monitoring in a relatively short period allows for the generation of fast time-resolved images, such as those shown in FIGS. 4A to 4D and FIG. 5. In other embodiments, the sensor 135 collects data over a longer period such that the detected emission is associated with more than one plasma generation event.

Analyze the indication of the detected emission (320). The indication is data received from the sensor system via signal 157. The signal 157 includes information describing the emission, such as the intensity of the detected emission. In some implementations, the signal 157 includes information about the location of the detected emission. For example, the signal 157 may include the readout of a two-dimensional array of sensors 135, where the intensity of the emission detected by each sensor in the array is included in the signal 157. Based on such information, the control system 150 determines the relative position of the detected emission.

As discussed above, in some implementations, the sensor system 130 includes a spectral filter module 137 and one or more spectral filters 136. In these implementations, the spectral filter 136 determines which wavelengths reach the one or more sensors 135. For example, the spectral filter 136 may include a filter designed to allow only wavelengths associated with H-α emission to reach the sensor 150. In such implementations, the signal 157 may include data indicating that the specific signal 157 includes information related to the detected H-α emission.

In addition, the signal 157 may include data related to the conditions under which the transmission is generated. For example, the signal 157 may include information about the sensor, such as exposure time. In another example, the signal 157 may include information about the environment in the vacuum chamber. Examples of such environmental information include temperature, pressure, and/or flow rate of gas 122 and information about light beam 106, such as pulse duration, pulse energy, and/or pulse wavelength.

The analysis module 152 of the control system 150 can perform various analyses on the detected transmitted instructions. Various analyses can be stored on the electronic storage 156 as computer programs that can be executed by the electronic processor 154, for example. Any type of analysis of the detected emissions can be performed. Refer to Figures 4A to 4D and Figure 5 for specific examples of data and corresponding analysis of that data. Analysis other than the analysis discussed in these examples may be performed by the analysis module 152.

Referring also to FIGS. 4A to 4D, examples of laser-induced fluorescence in which tin is emitted as a neutral atom are shown. In this example, tin is used as the target material, and the neutral atom tin may be tin fragments and/or tin that has not been converted into plasma 196. In the examples of FIGS. 4A to 4D, the sensor 135 is a camera that images the plasma forming part 123 and generates a two-dimensional image of the vacuum chamber 109.

In the example of FIGS. 4A to 4D, the sensor 135 is an enhanced charge coupled device (ICCD) with an exposure time of about 10 nanoseconds (ns), and the spectral filter 136 is placed on the sensor 135 and the plasma Between the formation parts 123, and the laser-induced fluorescence is formed by using the laser beam 115 from the detection laser 108 to excite the neutral tin atoms. In this example, the detection laser 108 is a tunable laser, and the laser beam 115 is a pulsed beam with pulses having a duration of several nanoseconds (for example, 10 ns or less). In addition, the detection laser 108 is tuned so that the laser beam 115 has a wavelength of 286.3 nm, which excites the neutral atom tin in the ground state. A certain fraction or percentage of neutral tin atoms is attenuated by the electronic transition of light emitted at 317.5 nm (laser-induced fluorescence). In this example, the spectral filter 136 is a bandpass filter centered at 317.5 nm. In addition, FIGS. 4A to 4D are related to a system using a pre-pulse and a main pulse. Therefore, these drawings are discussed in relation to FIG. 2.

Figure 4A shows the laser-induced fluorescence from the neutral tin in the vacuum chamber 109 at 200 nanoseconds (ns) after the pre-pulse (pulse 204_2 in Figure 2) interacts with the initial target 221p (Figure 2) Image 400A. 4B is an image 400B of laser-induced fluorescence from the neutral tin in the vacuum chamber 109 at 1900 ns after the pre-pulse interacts with the initial target 221p. 4C is an image 400C of the laser-induced fluorescence from the neutral tin in the vacuum chamber 109 at 300 ns after the pre-pulse (pulse 204_1 in FIG. 2) interacts with the modified target 220m (FIG. 2). 4D is an image 400D of laser-induced fluorescence from neutral tin in the vacuum chamber 109 at 900 ns after the main pulse interacts with the modified target 220m. Each pixel of each image 400A to 400D represents the amount of laser-induced fluorescence in a specific area of the vacuum chamber 109. The interaction between the main pulse and the modified target 220m is a plasma generating event.

The analysis module 152 determines the amount of tin ionized by the interaction by analyzing the images 400A to 400D to determine the intensity of certain spectral lines and the relative intensity of these lines. For example, the intensity of the emission from neutral tin can be compared with the intensity of ionized tin alone or dually to determine the fraction of atoms of the target material ionized after the plasma generation event. The intensity of the emission is proportional to the number of tin atoms (neutral tin atoms in the example of FIGS. 4A to 4D). Therefore, if the intensity of the emission from the neutral tin atom decreases while the intensity from the ionic substance increases, this is evidence that the ionization fraction is changed.

Other characteristics of images 400A to 400D can be analyzed. For example, the spatial distribution of intensity can be analyzed to estimate the distance traveled by the neutral tin atom and/or the speed of the neutral tin atom. For example, as seen in Figure 4D, the distance traveled from the origin (the azimuth of the interaction between the main pulse and the modified target 220m) and the elapsed time (in this example, 900 ns after the interaction) are given The speed of their neutral tin atoms.

In addition, the orientation angle of the fluorescence indicates the angle or orientation of the modified target 220m relative to the propagation direction of the main pulse, and the orientation angle of the fluorescence changes with the orientation of the modified target 220m. Therefore, the orientation of the modified target 220m can also be determined from images (such as images 400A to 400D).

The analysis module 152 also determines other information about the emission from the images 400A to 400D. For example, the analysis module 152 can apply a morphological operator to identify the ring structure 401 in the image 400C. The ring structure 401 expands over time in space, which is due to plasma generation events. The analysis module 152 also recognizes the ring structure 401 in the image 400D. By comparing the spatial characteristics of the ring structure 401 in the image 400C and the ring structure 401 in the image 400D, the velocity of tin atoms can be estimated. For example, the radius and/or diameter of the ring structure 401 in the images 401C and 401D can be compared and used to estimate the velocity of tin atoms when the amount of time between the images 400C and 400D is known. Furthermore, in some embodiments, the velocity of tin atoms is determined from a single image. For example, when the time from the interaction between the main pulse and the modified target 220m is known for a single image, the velocity of tin atoms can be determined from that single image. When the speed of tin atoms is determined from two or more images, the change in the speed of tin atoms can also be determined.

In addition, the morphological calculator can be used to determine the orientation of the ring structure 401. The orientation of the ring structure provides an indication of the orientation of the modified target 220m. For example, the major axis and minor axis of the ring structure 401 can be estimated after the ring structure 401 is identified, and the orientation of the ring structure 401 can be estimated from these axes.

The images 400A to 400D are provided as examples of data that the sensor system 130 can provide to the control system 150. Can monitor other types of laser-induced fluorescence. For example, an image showing the laser-induced fluorescence of the ions of the target material formed during the plasma generation event may be generated and provided to the control system 150. In another example, the emission from the gas 122 is analyzed. The gas 122 can be attributed to, for example, the heat in the vacuum chamber 109 from the pulse 104 (or pulse 204_1 and/or pulse 204_2 in FIG. 2), and/or ion movement in the gas 122, formed by the plasma 196, Or by the direct excitation of the detection laser 108 to emit light. FIG. 5 shows an example related to analyzing the emission from the gas 122 to determine the amount of energy deposited into the gas 122 due to a plasma generation event.

In the example of FIG. 5, the gas 122 is hydrogen and the sensor 135 is a camera that generates a two-dimensional image of the plasma formation site 123. The light pulse converts at least some of the target material into plasma that emits EUV light. In the example in Figure 5, the pulse energy is 860 millijoules (mJ), the pulse wavelength is 10 µm, and the pulse duration is 10 ns. The target is a tin droplet with a radius of about 50 µm. In this embodiment, the spectral filter 136 is a band-pass filter with a narrow spectral band centered on the H-α emission wavelength and is placed between the plasma formation site 123 and the sensor 135. Therefore, H-α emission reaches the sensor 135 and light of other wavelengths is substantially prevented from reaching the sensor 135.

(Among more images taken) Four two-dimensional images 500A to 500D are shown in FIG. 5. Obtain each of the images 500A to 500D at different times. Therefore, the images 500A to 500D are images of the relative intensity or amount of H-α emitted at the plasma formation site 123 at four different times.

The analysis module 152 is configured to analyze images such as 500A to 500D to determine the spatial characteristics of the shock wave or the explosion wave 504. The explosion wave 504 is formed in the gas 122 by a plasma generating event. The spatial characteristics may include, for example, the radius, diameter, orientation of the semi-major axis, orientation of the major axis, orientation of the minor axis, and/or the perimeter of the explosion wave 504. The analysis module 152 locates the explosion wave 504 in one or more of the images collected by the camera by applying the morphological calculator and imaging processing technology to the image. For example, the general shape of the explosion wave 504 is known as a circle, and the analysis module 152 can apply a morphological filter that detects a circular target in the image to locate the explosion wave 504 in the image from the camera. In another example, the analysis module 152 may apply an edge detector that relies on the intensity difference between the emission at the edge of the shock wave 504 and the background.

方程式(1)， 其中E為沈積至氣體122中的能量，r為爆炸波之半徑，ρ_o 為氣體122之密度，且t-t_o 為自電漿產生事件以來的時間。自在時間(t)處俘獲的電漿形成部位123之影像估計在特定時間(t)處的半徑(r)。分析模組152使用方程式1及在特定時間(t)處之爆炸波504的半徑之估計值估計沈積至氣體122中的能量之量。 分析模組152亦可自影像500A至500D判定其他資訊。舉例而言，圖5亦包括相對總H-α發射隨自電漿產生事件以來的時間變化的曲線。為產生曲線501，由攝影機在特定時間收集的影像中之每一像素的值經求和並經正規化。繪製隨時間變化之結果。影像500A至500D對應於包括於曲線501上的點中之四個。After the spatial characteristics of the explosion wave 504 have been estimated, the analysis module 152 applies the Taylor-Sedov equation to estimate the amount of energy (E) deposited in the gas 122. The Taylor-Sedov equation is:

Equation (1), where E is the energy deposited into the gas 122, r is the radius of the explosion wave, ρ _o is the density of the gas 122, and tt _o is the time since the plasma generation event. The radius (r) at a specific time (t) is estimated from the image of the plasma formation site 123 captured at the time (t). The analysis module 152 uses Equation 1 and the estimated value of the radius of the explosion wave 504 at a specific time (t) to estimate the amount of energy deposited into the gas 122. The analysis module 152 can also determine other information from the images 500A to 500D. For example, Figure 5 also includes a plot of relative total H-α emission as a function of time since the plasma generation event. To generate curve 501, the value of each pixel in the image collected by the camera at a specific time is summed and normalized. Plot the results over time. Images 500A to 500D correspond to four of the points included on the curve 501.

The data shown in FIGS. 4A to 4D and FIG. 5 are examples of the types of data that the sensor system 130 can provide to the control system 150 via the signal 157. However, the sensor system 130 can be configured to collect any other data about emission in the vacuum chamber 109, and the analysis module 152 can also be configured to analyze such data. For example, in some implementations, the plasma formation site 123 is monitored by more than one sensor 135, each of which has a spectrum corresponding to a specific emission line of the target material or gas 122 Filter 136. In these embodiments, each sensor 135 provides data specifying the spatial distribution of one of the emission lines of the substance at the plasma generation site 123 under the same operating conditions. The measured emission from each sensor is compared with the measured emission measured by other sensors to determine the nature of the environment in the vacuum chamber 109. For example, in the case of comparing different possible emissions from the target material, this comparison yields an estimate of the portion of the target material ionized to form the plasma 196.

In addition, the analysis module 152 can be configured to compare the spatial distribution of a certain type of emission at two different times after the plasma event. For example, in an implementation in which tin is used as the target material, the sensor 135 may be used with a filter 136 that only allows emission from ionized tin to reach the sensor 135. By comparing the emitted images of ionized tin obtained at different times, the analysis module 152 can estimate the speed and/or direction of the movement of tin ions.

Therefore, the analysis module 152 analyzes the information and data from the sensor system 130.

In addition to analyzing the data provided by the sensor system 130, the control system 150 also determines whether to adjust the EUV light source 100 or 200 based on the analysis (330). The adjustment of the EUV light source 100 or 200 may be the adjustment of any component of the EUV light source 100 or 200 and may include the adjustment of more than one component of the EUV light source 100 or 200. Whether to adjust and the nature of the adjustment (if any) depends on the results of the analysis discussed in (320).

The EUV light source 100 or 200 can be associated with various performance specifications, and analysis of emission can be used to determine whether the EUV light source 100 or 200 operates within one or more performance specifications. Conversion efficiency (CE) is an example of performance specifications. The conversion efficiency is the ratio of the energy supplied to the EUV light source 100 or 200 converted into EUV light. CE depends on the ionization fraction (the part of the target material that is converted into ions). As discussed above, analysis of emissions can be used to estimate the ionization fraction. To increase the ionization fraction, the duration and/or energy of the pulses in the beam 106 can be increased. Therefore, if the CE is lower than the specified CE, the control system 150 can send a command signal 159 to the light generating module 105 to change the duration and/or intensity of the pulse in the light beam 106.

In another example, the control system 150 can send a command signal 159 to the light generating module 205 (FIG. 2) to change the nature of the pre-pulse 204_2. As discussed above, the pre-pulse 204_2 adjusts the target by changing the shape and/or density of the target, so that the modified target 221m (FIG. 2) is more conducive to plasma generation. The light generating module 205 can be adjusted so that the intensity and/or duration of the pre-pulse 204_2 makes the modified target 211m generated later have a lower density and/or a different shape. In addition, in some embodiments, the control system 150 sends a command signal to the beam steering system 211_1 so that the position of the pre-pulse 204_2 relative to the initial destination site 224 is changed. In addition, the size of the target in the stream 121 can be adjusted to reduce the ionization fraction. In these embodiments, the command signal 159 is provided to the target supply system 110 to, for example, change the frequency of the vibration of the target forming device 117 so that the size of the target in the stream 121 is reduced.

In another example, analysis of the emission produces an estimated ion velocity that is greater than the desired ion velocity. In this example, the control system 150 sends a command signal 159 to the gas management system 140. The gas management system 140 causes the pressure of the gas 122 to increase so that the ions generated in the subsequent plasma generation event have a lower velocity. In yet another example, the analysis of the emission reveals a relatively high atomic weight of tin relatively shortly after the plasma generation event. The relatively high atomic weight of tin shortly after the plasma generation event is an indicator of excessive debris in the vacuum chamber 109. The control system 150 can send a command signal 159 to the gas management system 140 to increase the flow rate of the gas 122 and/or change the flow direction of the gas 122 to move debris away from the optical element 114.

In yet another example, the analysis of emission is used to generate an estimate of the amount of energy deposited into the gas 122. The estimated amount of energy is compared with the threshold and/or specification (for example, the range of acceptable amount of energy), and if the estimated amount of energy is higher than the threshold and/or does not meet the threshold, control The system 150 can issue a command to the light generating module 205 to reduce the power of the pre-pulse 204_2. Reducing the power or pre-pulse 204_2 generally reduces the amount of ions and/or pre-pulse plasma generated during the interaction between the pre-pulse 204_2 and the initial target 221p, and thereby reduces the energy deposited into the gas 122 .

In some embodiments, the control system 150 sends a command signal 159 to more than one component or system of the EUV light source 100 or 200. For example, in order to increase the ionization score, the control system 150 can send a command signal 159 to the light generating module 105 or 205, the target supply system 110 and the gas management system 140. In addition, in some cases, all performance specifications are met and/or EUV light source 100 can be operated acceptably without adjustments.

After determining whether to adjust the EUV light source 100 or 200, the control system 150 determines whether to continue monitoring the vacuum chamber 109 (340). If the monitoring continues, the routine 300 returns to (310). If the monitoring does not continue, the procedure 300 ends. Furthermore, in some embodiments, the program 300 runs continuously during the operation of the EUV light source 100 or 200, so that the control system continuously monitors the EUV light source 100 or 200. In these embodiments, the control system 150 does not determine whether to continue monitoring the vacuum chamber 109 and actually monitors the vacuum chamber 109 continuously and uninterruptedly during the operation of the EUV light source 100 or 200.

FIG. 6A is a block diagram of the lithography apparatus 600 including the source collector module SO. The lithography device 600 includes: • Illumination system (illuminator) IL, which is configured to adjust the radiation beam B (for example, EUV radiation); • A support structure (such as a mask stage) MT, which is constructed to support a patterned device (such as a mask or a reduction mask) MA, and is connected to a first positioner configured to accurately position the patterned device PM; • A substrate table (such as a wafer table) WT, which is constructed to hold a substrate (such as a resist coated wafer) W, and is connected to a second positioner PW configured to accurately position the substrate; and • A projection system (such as a reflective projection system) PS, which is configured to project the pattern imparted to the radiation beam B by the patterned device MA onto the target portion C (such as one or more dies) of the substrate W.

The lighting system may include various types of optical components for guiding, shaping or controlling radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof.

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 device, and other conditions (such as whether the patterned device is held in a vacuum environment). The support structure can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterned device. The supporting structure can be, for example, a frame or a table, which can be fixed or movable as required. The support structure can ensure that the patterned device, for example, is in a desired position relative to the projection system.

The term "patterned device" used should be broadly interpreted as referring to any device that can be used to impart a pattern to the radiation beam in its cross-section so as to create a pattern in the target portion of the substrate. The pattern imparted to the radiation beam may correspond to a specific functional layer in a device (such as an integrated circuit) generated in the target portion.

The patterned device can be transmissive or reflective. Examples of patterned devices include photomasks, programmable mirror arrays, and programmable LCD panels. Photomasks are well-known to us in lithography, and include mask types such as binary, alternating phase shift, and attenuated phase shift, as well as various hybrid mask types. An example of a programmable mirror array uses a matrix configuration of small mirrors, each of which can be individually tilted to reflect incident radiation beams in different directions. The tilted mirror imparts a pattern to the radiation beam reflected by the mirror matrix.

Similar to the illumination system IL, the projection system PS may include various types of optical components suitable for the exposure radiation used or other factors such as the use of vacuum, such as refraction, reflection, magnetic, electromagnetic, electrostatic or other types of optics Components, or any combination thereof. It may be necessary to use vacuum for EUV radiation, because other gases can absorb too much radiation. Therefore, the vacuum environment can be provided to the entire beam path by virtue of the vacuum wall and the vacuum pump.

In the example of FIGS. 6A and 6B, the device is reflective (for example, using a reflective mask). The lithography device may be of a type having two (dual stage) or more than two substrate stages (and/or two or more patterned device stages). In these "multi-stage" machines, 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.

Referring to FIG. 6A, the illuminator IL receives the extreme ultraviolet radiation beam from the source collector module SO. Methods for generating EUV light include, but are not necessarily limited to: using one or more emission lines in the EUV range to convert materials with at least one element (such as xenon, lithium or tin) into a plasma state. In one such method (often referred to as laser-generated plasma "LPP"), a laser beam is used to irradiate fuel (such as droplets, streams, or clusters of materials with desired spectral emission elements). ) To generate the required plasma. The source collector module SO may be part of an EUV radiation system including a laser (not shown in FIG. 6A) for providing a laser beam for exciting fuel. The resulting plasma emits output radiation, such as EUV radiation, which is collected using a radiation collector placed in the source collector module. For example, when a carbon dioxide (CO ₂ ) laser is used to provide a laser beam for fuel excitation, the laser and the source collector module can be separate entities.

In these cases, the laser is not considered to form part of the lithography device, and the radiation beam is transmitted from the laser to the source collector module by means of a beam delivery system including, for example, a suitable guide mirror and/or beam expander. In other cases, for example, when the source is a discharge generating plasma EUV generator (often referred to as a DPP source), the source can be an integral part of the source collector module.

The illuminator 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 of the intensity distribution in the pupil plane of the illuminator can be adjusted (usually referred to as σ outer and σ inner, respectively). In addition, the illuminator IL may include various other components, such as a faceted field mirror device and a faceted pupil mirror device. The illuminator IL can be used to adjust the radiation beam to have the desired uniformity and intensity distribution in its cross section.

The radiation beam B is incident on a patterned device (such as a photomask) MA that is held on a support structure (such as a photomask table) MT, and is patterned by the patterned device. After being reflected from the patterned device (such as a photomask) MA, the radiation beam B 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 position sensor PS2 (such as an interference device, a linear encoder or a capacitive sensor), the substrate table WT can be accurately moved, for example, to position different target parts C in the path of the radiation beam B in. 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 patterned device alignment marks M1, M2 and the substrate alignment marks P1, P2 can be used to align the patterned device (such as a photomask) MA and the substrate W.

The depicted device can be used in at least one of the following modes: 1. In the stepping mode, when projecting the entire pattern given to the radiation beam onto the target portion C at one time, the supporting structure (such as the mask stage) MT and the substrate stage WT are kept substantially stationary (that is, the 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. 2. In the scanning mode, when the pattern imparted to the radiation beam is projected onto the target portion C, the support structure (for example, the mask stage) MT and the substrate stage WT are simultaneously scanned (that is, a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure (such as the mask table) MT can be determined by the magnification (reduction ratio) and the image reversal characteristics of the projection system PS. 3. In another mode, when the pattern imparted to the radiation beam is projected onto the target portion C, the supporting structure (such as the mask stage) MT is kept substantially stationary, thereby holding the programmable patterned device, and Move or scan 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 variants of the above-described usage modes or completely different usage modes can also be adopted.

FIG. 6B shows in more detail an implementation of the lithography device 600, which includes a source collector module SO, an illumination system IL, and a projection system PS. The source collector module SO is constructed and configured such that a vacuum environment can be maintained in the enclosure structure 620 of the source collector module SO. The systems IL and PS are also contained in their own vacuum environment. LPP plasma source can be generated by laser to form EUV radiation emission plasma 2. The function of the source collector module SO is to deliver the EUV radiation beam 20 from the plasma 2 so that it is focused on the virtual source point. The virtual source point is generally referred to as an intermediate focus (IF), and the source collector module is configured such that the intermediate focus IF is located at or near the aperture 621 in the enclosure structure 620. The virtual source point IF is the image of the radiation emission plasma 2.

From the aperture 621 at the intermediate focus IF, the radiation traverses the illumination system IL, which in this example includes a faceted field mirror device 22 and a faceted pupil mirror device 24. These devices form so-called "fly-eye" illuminators, which are configured to provide the desired angular distribution of the radiation beam 21 at the patterned device MA, and the radiation intensity at the patterned device MA (as shown by reference 660) It needs uniformity. After the reflection of the light beam 21 at the patterned device MA held by the support structure (mask stage) MT, a patterned light beam 26 is formed, and the patterned light beam 26 is transmitted by the projection system PS through the reflective elements 28, 30 The image is imaged onto the substrate W held by the substrate table WT. In order to expose the target portion C on the substrate W, a pulse of radiation is generated while the substrate table WT and the patterned device table MT perform synchronized movement to scan the pattern on the patterned device MA through the illumination slit.

Each system IL and PS is configured in its own vacuum or near-vacuum environment, which is defined by an enclosure structure similar to the enclosure structure 620. More elements than shown may 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. 6B, there may also be one to six additional reflective elements in the illumination system IL and/or the projection system PS.

Considering the source collector module SO in more detail, the laser energy source including the laser 623 is configured to deposit the laser energy 624 into the fuel including the target material. The target material can be any material that emits EUV radiation in a plasma state, such as xenon (Xe), tin (Sn), or lithium (Li). Plasma 2 is a highly ionized plasma with an electron temperature of tens of electron volts (eV). Other fuel materials, such as Tb and Gd, can be used to generate higher energy EUV radiation. The high-energy radiation generated during the de-excitation and recombination of the plasma is emitted from the plasma, collected by the near-normal incidence collector 3, and focused on the aperture 621. Plasma 2 and aperture 621 are respectively located at the first focus and second focus of the collector CO.

Although the collector 3 shown in FIG. 6B is a single curved mirror surface, the collector may take other forms. For example, the collector may be a Schwarzschild collector with two radiation collection surfaces. In one embodiment, the collector may be a grazing incidence collector comprising a plurality of substantially cylindrical reflectors nested within each other.

In order to deliver fuel (which is, for example, liquid tin), a droplet generator 626 is arranged in the enclosure 620, and the droplet generator 626 is configured to emit a high-frequency droplet stream 628 toward a desired part of the plasma 2. The droplet generator 626 may be the target forming device 216 and/or include an adhesive such as an adhesive 234. In operation, the laser energy 624 is delivered synchronously with the operation of the droplet generator 626 to deliver radiation pulses to make each fuel droplet become plasma 2. The delivery frequency of the droplets can be several kilohertz, for example, 50 kHz. In practice, the laser energy 624 is delivered with at least two pulses: before the pre-pulse with limited energy reaches the plasma site, the pre-pulse is delivered to the droplet to vaporize the fuel material into a small cloud, and then, The main pulse of laser energy 624 is delivered to the cloud at the desired location to generate plasma 2. The trap 630 is provided on the opposite side of the enclosure structure 620 to trap fuel that has not become plasma for whatever reason.

The droplet generator 626 includes a reservoir 601 containing a fuel liquid (such as molten tin), a filter 669 and a nozzle 602. The nozzle 602 is configured to inject droplets of fuel liquid toward the plasma 2 formation site. A droplet of fuel liquid can be ejected from the nozzle 602 by a combination of the pressure in the reservoir 601 and the vibration applied to the nozzle by a piezoelectric actuator (not shown).

Those familiar with the art will know that reference axes X, Y, and Z can be defined to measure and describe the geometry and behavior of the device, its various components, and the radiation beams 20, 21, and 26. At each part of the device, the local reference coordinate system of X-axis, Y-axis and Z-axis can be defined. In the example of FIG. 6B, the Z axis roughly coincides with the directional optical axis O at a given point in the system, and is substantially perpendicular to the plane of the patterned device (reducing mask) MA and perpendicular to the plane of the substrate W. In the source collector module, the X-axis roughly coincides with the direction of the fuel stream 628, and the Y-axis is orthogonal to the direction of the fuel stream 628, which is indicated from the page, as indicated in FIG. 6B. On the other hand, in the vicinity of the support structure MT holding the zoom mask MA, the X axis is substantially transverse to the scanning direction aligned with the Y axis. For convenience, in this area of the schematic diagram in Figure 6B, the X axis is pointed out from the page, again as marked. These designations are conventional in this technology and will be adopted in this article for convenience. In principle, any reference coordinate system can be selected to describe the device and its behavior.

Many additional components used in the overall operation of the source collector module and the lithography device 600 exist in a typical device, but are not described here. These components include configurations for reducing or mitigating the effects of pollution in the enclosed vacuum, for example, to prevent deposits of fuel materials from damaging or weakening 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 device 600.

Referring to Figure 7, an implementation of the LPP EUV light source 700 is shown. The light source 700 can be used as the source collector module SO in the lithography device 600. In addition, the light generating module 105 in FIG. 1 may be a part of driving the laser 715. The driving laser 715 can be used as the laser 623 (Figure 6B).

The LPP EUV light source 700 is formed by irradiating the target mixture 714 at the plasma formation site 705 with an amplified light beam 710 that travels along a beam path toward the target mixture 714. The target material discussed with respect to FIGS. 1A, 2 and 3 and the target in the stream 121 of FIGS. 1A and 2 may be or include the target mixture 714. The plasma formation site 705 is located in the interior 707 of the vacuum chamber 730. When the amplified light beam 710 is irradiated on the target mixture 714, the target material in the target mixture 714 is converted into a plasma state of elements having emission lines in the EUV range. The resulting plasma has certain characteristics that depend on the composition of the target material in the target mixture 714. 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 700 also includes a supply system 725, which delivers, controls and guides liquid droplets, liquid streams, solid particles or clusters, solid particles contained in droplets, or solid particles contained in a liquid stream. Target mixture 714. The target mixture 714 includes a target material, such as water, tin, lithium, xenon, or any material that has an emission line in the EUV range when converted into a plasma state. 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. The target mixture 714 may also include impurities such as non-target particles. Therefore, in the absence of impurities, the target mixture 714 is composed of only the target material. The target mixture 714 is delivered by the supply system 725 into the interior 707 of the chamber 730 and delivered to the plasma formation site 705.

The light source 700 includes a driving laser system 715 that generates an amplified light beam 710 due to the population inversion in one of the laser systems 715 or several gain media. The light source 700 includes a beam delivery system between the laser system 715 and the plasma formation site 705, and the beam delivery system includes a beam delivery system 720 and a focusing assembly 722. The beam delivery system 720 receives the amplified light beam 710 from the laser system 715, and turns and modifies the amplified light beam 710 as necessary and outputs the amplified light beam 710 to the focusing assembly 722. The focusing assembly 722 receives the amplified light beam 710 and focuses the light beam 710 to the plasma formation site 705.

In some implementations, the laser system 715 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 devices forming a laser cavity. Therefore, the laser system 715 will generate an amplified beam 710 due to the population inversion in the gain medium of the laser amplifier even in the absence of a laser cavity. In addition, the laser system 715 can generate the amplified beam 710 as a coherent laser beam in the presence of a laser cavity to provide sufficient feedback to the laser system 715. The term "amplified light beam" covers one or more of the following: light from laser system 715 that is only amplified but not necessarily coherent laser oscillation, and light from laser system 715 that is amplified and also coherent laser Shoot oscillating light.

The optical amplifier in the laser system 715 may include a filling gas (including CO ₂ ) as a gain medium, and may have a gain greater than or equal to 800 times for amplification at a wavelength between about 9100 nm and about 11000 nm, and especially at about 10600. Light under nm. Suitable for use in laser amplifiers and laser 715. The system may include a pulsed laser device, for example a 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) operation of DC or RF excitation produces radiation at about 9300 nm or about 10600 nm. For example, the pulse repetition rate can be 50 kHz. The optical amplifier in the laser system 715 may also include a cooling system, such as water, which can be used when the laser system 715 is operated at a higher power.

The light source 700 includes a collector mirror 735 having an aperture 740 to allow the amplified light beam 710 to pass through and reach the plasma formation site 705. The collector mirror 735 can be, for example, an ellipsoidal mirror with a primary focus at the plasma formation site 705 and a secondary focus (also called an intermediate focus) at the middle site 745, where EUV light can be output from the light source 700 and It can be input to, for example, an integrated circuit lithography tool (not shown in the figure). The light source 700 may also include an open-ended hollow cone-shaped shield 750 (such as a gas cone), which is tapered from the collector mirror 735 toward the plasma formation site 705 to reduce entry into the focusing assembly 722 and/or light beam The amount of debris generated by the plasma of the system 720 is conveyed while allowing the amplified light beam 710 to reach the plasma formation site 705. For this purpose, an air flow can be provided in the shield, and the air flow is guided toward the plasma formation site 705.

The light source 700 may also include a main control controller 755 connected to the droplet position detection feedback system 756, the laser control system 757, and the beam control system 758. The light source 700 may include one or more targets or droplet imagers 760 that provide an output indicating the position of the droplet, for example, relative to the plasma formation site 705 and provide this output to the small A drop position detection and feedback system 756, 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. Therefore, the droplet position detection feedback system 756 provides the droplet position error as an input to the main control controller 755. Therefore, the main control controller 755 can provide the laser position, direction, and timing correction signals to, for example, the laser control system 757 that can be used to, for example, control the laser timing circuit and/or to the beam control system 758. The beam control system is used to control the position of the amplified beam and the shaping of the beam delivery system 720 to change the position and/or the focus of the beam focal spot in the chamber 730.

The supply system 725 includes a target material delivery control system 726 that is operable to modify the release point of the droplets as released by the target material supply device 727 in response to, for example, a signal from the main control controller 755, To correct the error in the droplet reaching the desired plasma formation site 705. The target material supply device 727 includes a target forming device using an adhesive (such as an adhesive 234).

In addition, the light source 700 may include light source detectors 765 and 770 for measuring one or more EUV light parameters, including but not limited to pulse energy, energy distribution that varies according to wavelength, and specific wavelength bands. The energy inside, the energy outside a specific wavelength band, and the angular distribution of EUV intensity and/or average power. The light source detector 765 generates a feedback signal for the main control controller 755 to use. The feedback signal may, for example, indicate errors in parameters such as timing and focus of laser pulses that are properly intercepted at the appropriate place and time for effective and efficient EUV light generation.

The light source 700 may also include a guide laser 775, which can be used to align the various sections of the light source 700 or assist in steering the amplified light beam 710 to the plasma formation site 705. In combination with the guide laser 775, the light source 700 includes a metrology system 724, which is placed in the focusing assembly 722 to sample a portion of the light from the guide laser 775 and the amplified beam 710. In other embodiments, the metrology system 724 is placed within the beam delivery system 720. The metrology system 724 may include an optical element that samples or re-directs 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 710. The beam analysis system is formed by the metrology system 724 and the main control controller 755. This is because the main control controller 755 analyzes the light sampled by the self-guided laser 775 and uses this information to adjust the focus assembly 722 via the beam control system 758 The components.

Therefore, in summary, the light source 700 generates an amplified light beam 710, which is guided along the beam path to irradiate the target mixture 714 at the plasma formation site 705 to convert the target material in the mixture 714 into emission Plasma of light within the EUV range. The amplified light beam 710 operates at a specific wavelength determined based on the design and properties of the laser system 715 (which is also referred to as the driving laser wavelength). In addition, the amplified light beam 710 can be a laser when the target material provides sufficient feedback back to the laser system 715 to generate coherent laser light or when the driving laser system 715 includes appropriate optical feedback to form a laser cavity. beam.

Previously, only the principles of the embodiments of the present invention have been explained. Therefore, it should be understood that those skilled in the art will be able to design various configurations. Although not explicitly described or shown herein, the configurations embody the principles of the present invention and are included in its spirit and scope. In addition, all the examples and conditional language described in this article are mainly intended to be used for educational purposes only and to assist readers in understanding the principles of the present invention and the concepts contributed by the inventor to promote the field, and all examples should be understood as not Limited to these specific examples and conditions. In addition, all statements describing the principles, aspects and embodiments of the present invention and specific examples thereof are intended to cover both structural equivalents and functional equivalents. In addition, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future (that is, any elements developed that perform the same function regardless of structure).

It is intended to read this description of the exemplary embodiment in conjunction with the accompanying drawings, which are considered to be part of the entire written description. In the description, such as "lower", "upper", "horizontal", "vertical", "above", "below", "up", "down", "top" and The relative terms of "bottom" and its derivatives (eg, "horizontally", "downwardly", "upwardly", etc.) should be interpreted to refer to the orientation as described below or as shown in the diagrams discussed below. These relative terms are only for convenience of description and do not require the device to be constructed or operated in a specific orientation. Terms related to attachment, coupling, and the like (such as “connected” and “interconnected”) refer to the relationship between structures that are fastened or attached to each other directly or indirectly via intervening structures, and movable or Rigid attachment or relationship, unless explicitly described otherwise.

Although the present invention has been described with respect to exemplary embodiments, it is not limited thereto. Other implementation schemes are within the scope of the patent application. The scope of the attached patent application shall be broadly regarded as including other variants and embodiments of the present invention, which can be used by those familiar with the art without departing from the scope and scope of equivalents of the present invention manufacture.

The following items can be used to further describe the embodiments of the present invention: 1. A system that includes: A vacuum chamber comprising an inner zone, wherein the inner zone is configured to receive a target and a light beam, the target includes a target material, and the target material emits extreme ultraviolet (EUV) when in a plasma state Light; A detection system configured to image the inner zone, the detection system being configured to detect light emission from atoms, ions, or molecules in the inner zone and generate the light emission in the inner zone One representation of a spatial distribution; and A control system, which is coupled to the detection system, the control system is configured to: Analyzing the representation of the spatial distribution of the light emission to determine a spatial distribution of the light emission from atoms, ions or molecules in the inner region; and Based on the spatial distribution of the light emission, it is determined whether to adjust at least one property of the light beam and/or at least one property of the vacuum chamber. 2. As in the system of Clause 1, where the light emission includes fluorescence. 3. As in the system of Clause 2, where the fluorescence includes laser-induced fluorescence. 4. Such as the system of Clause 1, it further includes one or more spectral filters configured to be positioned relative to the detection system, and the spectral filters are configured to allow only certain wavelengths to reach the detection system.测系统。 Measurement system. 5. The system as in Clause 4, wherein each of the one or more spectral filters is configured to transmit light having a wavelength of one of a plurality of emission lines of the target material. 6. The system as in Clause 5, wherein at least one of the one or more spectral filters is configured to transmit a wavelength in a visible light range. 7. The system as in Clause 4, wherein the vacuum chamber is further configured to contain a gas in the inner region, and the spectral filter is configured to transmit the light at an emission line of the gas One wavelength of light. 8. Such as the system of Clause 1, wherein the control system is configured to receive multiple representations of the internal area, each of the multiple representations is associated with a different time, and the control system is configured Analyzing the representation of the inner zone includes that the control system is configured to analyze each of the plurality of representations to determine the space in which the light is emitted in the inner zone at each of the different times distributed. 9. As in the system of clause 8, wherein the light emission in the inner zone is caused by an energy event in one of the inner zones, and the different times are all times that occur after the energy event. 10. The system as in clause 9, wherein the energy event includes an interaction between the beam and the target, and the light emission is an emission from: (a) the target material; (b) by A plasma formed by the interaction between the light beam and the target material; and/or (c) fragments formed by the interaction between the light beam and the target. 11. The system as in Clause 1, wherein the control system is configured to receive an extended exposure representation of the internal area, and the extended exposure representation of the internal area includes the transmitted data in the internal area within a time period An average value of this spatial distribution. 12. The system of clause 9, wherein the vacuum chamber is further configured to contain a gas in the inner zone, the energy event includes adding energy to an interaction of the gas, and the light emission is from the One of the gas is emitted. 13. The system of clause 12, wherein the interaction of adding energy to the gas includes: (a) an interaction between the light beam and the gas; (b) the gas and the light beam and the target And/or (c) an interaction between ions and the gas. 14. The system as in Clause 1, wherein the control system is configured to analyze the representation to determine a spatial distribution of the light emission in the inner region includes one of the control system configured to estimate the intensity of the light emission Shape and/or a spatial distribution. 15. As the system of item 1, it further includes: A first spectral filter configured to transmit light having a wavelength in a first wavelength band; and A second spectral filter configured to transmit light having a wavelength in a second wavelength band, and wherein the control system is configured to analyze the representation includes: the control system is configured to estimate An amount of light emission in the first wavelength band and an amount of light emission in the second wavelength band is estimated, and the control system is further configured to compare the light emission at the first wavelength band based on The estimated amount of and the estimated amount of light emission at the second wavelength band are used to estimate an ionization fraction of the target material. 16. The system as in Item 15, wherein the control system determines whether to adjust at least one property of the beam based on the estimated ionization fraction. 17. The system as in Clause 16, wherein the control system determines whether to adjust the direction of one of the beams based on the estimated ionization fraction. 18. The system of Clause 1, wherein the light beam includes a main pulsed beam, and the main pulsed beam includes an energy sufficient to convert at least some of the target material into a plasma that emits EUV light. 19. The system as in Clause 1, where the beam includes a pre-pulse beam. 20. The system as in Clause 4, wherein the control system is configured to analyze the representation and further includes that the control system is configured to compare the spatial distributions of the fluorescent lights in the internal area at least at two different times. Estimate a velocity of the ions in the inner region, and compare the estimated velocity with a velocity specification, and the control system can be configured to determine whether to adjust the gas based on the comparison of the estimated velocity with the velocity specification One pressure. 21. Such as the system of item 1, where the representation of the spatial distribution includes one of a two-dimensional representation. 22. The system of clause 1, wherein the beam includes a pulsed beam, and the control system is configured to adjust at least one property of the beam includes the control system configured to adjust one of the pulsed beams to occur later At least one property of the pulse. 23. An EUV light source, which includes: A vacuum chamber configured to: contain a gas in an internal region and receive a target and a light beam, the target including a target material emitting extreme ultraviolet (EUV) light in a plasma state; A monitor comprising at least one sensor configured to detect emission from the gas in the inner region and generate an indication of the detected emission; and A control system, which is coupled to the monitor, the control system is configured to: Analyze the indication of the detected emission; and Based on the analysis, it is determined whether to adjust at least one property of the light beam and/or at least one property of the vacuum chamber. 24. Such as the EUV light source of Clause 23, wherein the monitor includes a detection system configured to image a part of the inner region and generate a spatial distribution of the detected emission in the part. 25. Such as the EUV light source of clause 24, in which the control system is configured to receive a plurality of indications within a period of time, each indication indicating the detected emission in that part of the time period at a different time A spatial distribution, and the control system is configured to determine whether to adjust at least one property of the light beam and/or at least one property of the vacuum chamber based on two or more of the plurality of representations. 26. Such as the EUV light source of Clause 23, wherein the gas includes hydrogen, and the detected emission includes a H alpha (H-α) and/or H beta (H-β) emission from the hydrogen. 27. As the EUV light source in item 24, it further includes: A first spectral filter configured to transmit a first wavelength band; and A second spectral filter configured to transmit a second wavelength band, wherein in operational use, the first spectral filter and the second spectral filter are in the part and the detection system Between; and The control system is configured to analyze the detected emissions. The control system is configured to compare a representation of the emission transmitted by the first spectral filter with the emission transmitted by the second spectral filter. A representation; and whether to adjust at least one property of the beam and/or at least one property of the vacuum chamber is based on the comparison. 28. Such as the EUV light source of Clause 24, which further includes a pressure controller coupled to the inside of the vacuum chamber, and the pressure controller is configured to change one of the gases in the inside of the vacuum chamber Pressure, and wherein the control system is coupled to the pressure controller. 29. A method for controlling an EUV light source, the method includes: Providing a target to a target zone in a vacuum chamber, the vacuum chamber containing a gas in an internal zone; Promote an interaction between a light beam and the target in the target area; Detect light emission from atoms, ions and/or molecules in the inner region of the vacuum chamber, the light emission being a response to an energy event in the vacuum chamber, the energy event including adding energy to the Target and/or an event of the gas; Analyzing the detected light emission to determine a spatial distribution of light emission in the inner region; and Based on the analysis, it is determined whether to adjust a property of the light beam and/or the gas.

Other implementation schemes are within the scope of the patent application.

2: Plasma 3: collector 21: Radiation beam 22: Faceted field mirror device 24: Faceted pupil mirror device 26: Patterned beam 28: reflective element 30: reflective element 100: extreme ultraviolet (EUV) light source 102: Pulse duration 103: Peak power 104: Pulse 105: light generating module 106: beam 107: Optical Path 108: Detection laser 109: Vacuum chamber 110: Target Supply System 111: beam delivery system 112: Optical components 113: Pore 114: optical components 115: Laser beam 116: reflective surface 117: Target Formation Device 118: Reservoir 119: Hole 121: Goal 121p: target 122: Gas 123: Plasma formation site 130: sensor system 134: Sensor Module 135: Sensor 136: Spectral filter 137: Spectral filter module 140: Gas Management System 150: control system 152: Analysis Module 154: electronic processor 156: Electronic Storage 157: Signal 158: I/O interface 159: Command signal 195: Fragment 196: Plasma 197: Light 198: EUV light 199: Lithography Device 200: EUV light source 204_1: pulse 204_2: Pulse 205: Light Generation Module 206_1: First beam 206_2: Second beam 207_1: beam path 207_2: beam path 208_1: the first optical source 208_2: second optical source 211_1: beam delivery system/beam steering system 211_2: beam delivery system 221m: modified target 221p: initial goal 224: initial target area 300: program 400A: Video 400B: Video 400C: Image 400D: image 401: ring structure 500A: Video 500B: Video 500C: Image 500D: image 501: Curve 504: Shock Wave/Explosion Wave 600: Lithography device 601: Reservoir 602: Nozzle 620: enclosure structure 621: Pore 623: Laser 624: Laser Energy 626: Droplet Generator 628: High-frequency droplet stream/fuel stream 630: Interceptor 660: reference 669: filter 700: LPP EUV light source 705: Plasma formation site 707: Inside the vacuum chamber 710: Amplified beam 714: Target Mix 715: Drive laser/laser system 720: beam delivery system 722: Focus Assembly 725: Supply System 726: Target Material Delivery Control System 727: Target Material Supply Device 730: vacuum chamber 735: collector mirror 740: Pore 745: middle part 750: Open-ended hollow conical shield 755: Master Controller 756: Droplet position detection feedback system 757: Laser Control System 758: Beam Control System 760: Target or droplet imager 765: Light Source Detector 770: Light Source Detector 775: Guided Laser B: radiation beam C: target part IL: lighting system/illuminator MA: Patterned device M1: Patterned device alignment mark M2: Patterned device alignment mark P: pressure P1: substrate alignment mark P2: substrate alignment mark PM: the first locator PS: Projection system PS1: Position sensor PS2: position sensor PW: second locator SO: Source Collector Module W: substrate WT: substrate table

The present invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to convention, the various features of the schema are not necessarily to scale. In contrast, for clarity, the size of various features can be arbitrarily enlarged or reduced. Throughout this specification and drawings, similar numbers represent similar features.

Figure 1A is a block diagram of an example of an extreme ultraviolet (EUV) light source.

Figure 1B is an example of the time curve of the optical pulse.

Fig. 2 is a block diagram of another example of an extreme ultraviolet (EUV) light source.

Fig. 3 is a flowchart of an example of a procedure for controlling EUV light sources.

Figures 4A to 4D show example images of laser-induced fluorescence.

Figure 5 shows example data related to the analysis of light emission from gas.

6A and 6B are block diagrams of examples of lithography devices.

Figure 7 is a block diagram of an example of an EUV light source.

100: extreme ultraviolet (EUV) light source

104: Pulse

105: light generating module

106: beam

107: Optical Path

108: Detection laser

109: Vacuum chamber

110: Target Supply System

111: beam delivery system

112: Optical components

113: Pore

114: optical components

115: Laser beam

116: reflective surface

117: Target Formation Device

118: Reservoir

119: Hole

121: Goal

121p: target

122: Gas

123: Plasma formation site

130: sensor system

134: Sensor Module

135: Sensor

136: Spectral filter

137: Spectral filter module

140: Gas Management System

150: control system

152: Analysis Module

154: electronic processor

156: Electronic Storage

157: Signal

158: I/O interface

159: Command signal

195: Fragment

196: Plasma

197: Light

198: EUV light

199: Lithography Device

P: pressure

Claims (29)

A system that includes: A vacuum chamber comprising an inner zone, wherein the inner zone is configured to receive a target and a light beam, the target includes a target material, and the target material emits extreme ultraviolet (EUV) when in a plasma state Light; A detection system configured to image the inner zone, the detection system being configured to detect light emission from atoms, ions, or molecules in the inner zone and generate the light emission in the inner zone One representation of a spatial distribution; and A control system, which is coupled to the detection system, the control system is configured to: Analyzing the representation of the spatial distribution of the light emission to determine a spatial distribution of the light emission from atoms, ions or molecules in the inner region; and Based on the spatial distribution of the light emission, it is determined whether to adjust at least one property of the light beam and/or at least one property of the vacuum chamber. Such as the system of claim 1, wherein the light emission includes fluorescence. Such as the system of claim 2, wherein the fluorescence includes laser-induced fluorescence. Such as the system of claim 1, which further includes one or more spectral filters configured to be positioned relative to the detection system, the spectral filters being configured to allow only certain wavelengths to reach the detection system . The system of claim 4, wherein each of the one or more spectral filters is configured to transmit light having a wavelength in one of a plurality of emission lines of the target material. The system of claim 5, wherein at least one of the one or more spectral filters is configured to transmit a wavelength in a visible light range. The system of claim 4, wherein the vacuum chamber is further configured to contain a gas in the inner region, and the spectral filter is configured to transmit a wavelength at an emission line of the gas Of light. Such as the system of claim 1, wherein the control system is configured to receive a plurality of representations of the internal area, each of the plurality of representations is associated with a different time, and the control system is configured to analyze The representation of the inner zone includes that the control system is configured to analyze each of the plurality of representations to determine the spatial distribution of the light emission in the inner zone at each of the different times. Such as the system of claim 8, wherein the light emission in the inner zone is caused by an energy event in the inner zone, and the different times are all times that occur after the energy event. The system of claim 9, wherein the energy event includes an interaction between the light beam and the target, and the light emission is an emission from: (a) the target material; (b) by the light beam A plasma formed by the interaction with the target material; and/or (c) fragments formed by the interaction between the beam and the target. Such as the system of claim 1, wherein the control system is configured to receive an extended exposure representation of the internal region, and the extended exposure representation of the internal region includes the space of the emission in the internal region within a time period The mean of one of the distributions. The system of claim 9, wherein the vacuum chamber is further configured to contain a gas in the inner region, the energy event includes an interaction that adds energy to the gas, and the light emission is from one of the gas emission. The system of claim 12, wherein the interaction of adding energy to the gas includes: (a) an interaction between the light beam and the gas; (b) the gas and an interaction between the light beam and the target An interaction between a plasma formed by the interaction; and/or (c) an interaction between an ion and the gas. Such as the system of claim 1, wherein the control system is configured to analyze the representation to determine a spatial distribution of the light emission in the inner region includes a shape and the control system configured to estimate the intensity of the light emission / Or a spatial distribution. Such as the system of claim 1, which further includes: A first spectral filter configured to transmit light having a wavelength in a first wavelength band; and A second spectral filter configured to transmit light having a wavelength in a second wavelength band, and wherein The control system is configured to analyze the representation includes: the control system is configured to estimate a quantity of light emission in the first wavelength band and estimate a quantity of light emission in the second wavelength band, and the control The system is further configured to estimate an ionization fraction of the target material based on comparing the estimated amount of light emission at the first wavelength band with the estimated amount of light emission at the second wavelength band. The system of claim 15, wherein the control system determines whether to adjust at least one property of the beam based on the estimated ionization fraction. Such as the system of claim 16, wherein the control system determines whether to adjust a pointing direction of the light beam based on the estimated ionization fraction. The system of claim 1, wherein the beam includes a main pulsed beam, and the main pulsed beam includes an energy sufficient to convert at least some of the target material into a plasma that emits EUV light. Such as the system of claim 1, wherein the beam includes a pre-pulse beam. Such as the system of claim 4, wherein the control system is configured to analyze the representation further includes the control system is configured to compare the spatial distributions of the fluorescence in the inner region at least at two different times to estimate the A velocity of the ions in the inner region is compared with the estimated velocity and a velocity specification, and the control system is configured to determine whether to adjust a pressure of the gas based on the comparison of the estimated velocity and the velocity specification. Such as the system of claim 1, wherein the representation of the spatial distribution includes a representation of a two-dimensional representation. Such as the system of claim 1, wherein the light beam includes a pulsed light beam, and the control system is configured to adjust at least one property of the light beam includes the control system configured to adjust the pulse of a pulse that occurs later in the pulsed light beam At least one property. An EUV light source, which includes: A vacuum chamber configured to: contain a gas in an internal region and receive a target and a light beam, the target including a target material emitting extreme ultraviolet (EUV) light in a plasma state; A monitor comprising at least one sensor configured to detect emission from the gas in the inner region and generate an indication of the detected emission; and A control system, which is coupled to the monitor, the control system is configured to: Analyze the indication of the detected emission; and Based on the analysis, it is determined whether to adjust at least one property of the light beam and/or at least one property of the vacuum chamber. Such as the EUV light source of claim 23, wherein the monitor includes a detection system configured to image a portion of the inner region and generate a spatial distribution representation of the detected emission in the portion. Such as the EUV light source of claim 24, wherein the control system is configured to receive a plurality of representations within a period of time, each of which indicates a space of the detected emission in the portion at a different time in the period of time The control system is configured to determine whether to adjust at least one property of the light beam and/or at least one property of the vacuum chamber based on two or more of the plurality of representations. Such as the EUV light source of claim 23, wherein the gas includes hydrogen, and the detected emission includes a H alpha (H-α) and/or H beta (H-β) emission from the hydrogen. Such as the EUV light source of claim 24, which further includes: A first spectral filter configured to transmit a first wavelength band; and A second spectral filter configured to transmit a second wavelength band, wherein in operational use, the first spectral filter and the second spectral filter are in the part and the detection system Between; and The control system is configured to analyze the detected emissions. The control system is configured to compare a representation of the emission transmitted by the first spectral filter with the emission transmitted by the second spectral filter. A representation; and whether to adjust at least one property of the beam and/or at least one property of the vacuum chamber is based on the comparison. Such as the EUV light source of claim 24, which further includes a pressure controller coupled to the inside of the vacuum chamber, the pressure controller being configured to change a pressure of the gas in the inside of the vacuum chamber, And wherein the control system is coupled to the pressure controller. A method for controlling an EUV light source, the method includes: Providing a target to a target zone in a vacuum chamber, the vacuum chamber containing a gas in an internal zone; Promote an interaction between a light beam and the target in the target area; Detect light emission from atoms, ions and/or molecules in the inner region of the vacuum chamber, the light emission being a response to an energy event in the vacuum chamber, the energy event including adding energy to the Target and/or an event of the gas; Analyzing the detected light emission to determine a spatial distribution of light emission in the inner region; and Based on the analysis, it is determined whether to adjust a property of the light beam and/or the gas.

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