Extreme ultraviolet radiation source, method for generating extreme ultraviolet radiation, and method for pattern formation

Abstract

The disclosed embodiments provide an extreme ultraviolet radiation source, a method for generating extreme ultraviolet radiation, and a method for pattern formation. The method for generating extreme ultraviolet radiation includes simultaneously irradiating two or more target droplets with a laser in an extreme ultraviolet radiation source device to generate extreme ultraviolet radiation, and collecting and guiding the extreme ultraviolet radiation generated from the two or more target droplets through an imaging mirror.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to a method for generating radiation, and more particularly to a method for generating extreme ultraviolet radiation. Background Art

[0002] The wavelength of radiation used in lithography in semiconductor manufacturing has been reduced from ultraviolet to deep ultraviolet (DUV) and recently to extreme ultraviolet (EUV). Further reductions in feature size require further improvements in the resolution of lithography, which can be achieved using extreme ultraviolet lithography (EUVL). EUVL employs radiation with wavelengths of about 1 to 100 nanometers. One method of generating EUV radiation is laser-produced plasma (LPP). In an LPP-based EUV light source, a high-power laser beam is focused on a small droplet target of a metal (e.g., tin) to form a highly ionized plasma that emits EUV radiation with a maximum peak at 13.5 nanometers. Improving the efficiency of EUV light sources based on laser-produced plasma is urgently needed. Summary of the invention

[0003] An object of the embodiments of the present disclosure is to provide a method for generating extreme ultraviolet radiation to solve at least one of the above problems.

[0004] According to some embodiments of the present disclosure, a method for generating extreme ultraviolet radiation is provided, comprising simultaneously irradiating two or more target droplets with a first laser beam in an extreme ultraviolet radiation source device to generate extreme ultraviolet radiation, and collecting and guiding the extreme ultraviolet radiation generated from the two or more target droplets through an imaging mirror.

[0005] According to some embodiments of the present disclosure, a method for generating extreme ultraviolet radiation is provided, comprising generating two or more stripes by a first laser beam passing through a first slit pair, irradiating two or more target droplets through the two or more stripes to generate extreme ultraviolet radiation, wherein each of the two or more target droplets simultaneously passes through one of the two or more stripes, and collecting and guiding the extreme ultraviolet radiation generated from the two or more target droplets through an imaging mirror.

[0006] According to some embodiments of the present disclosure, there is provided an extreme ultraviolet radiation source, comprising a first laser source, a collecting mirror, a droplet generator, an optical system, and a controller. The first laser source is configured to generate a first laser beam. The collecting mirror comprises two or more slits. The droplet generator is configured to release two or more target droplets simultaneously on a plurality of first parallel lines in a first plane. The optical system is configured to divide the first laser beam into two or more parts, and pass two or more parts of the first laser beam through two or more slits to generate two or more first stripes parallel to the paths of the two or more target droplets. The controller couples and controls the first laser source and the droplet generator, wherein the controller is configured to emit laser pulses of the first laser source to irradiate the two or more target droplets released simultaneously through the two or more first stripes, wherein each first stripe irradiates one droplet. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The various aspects of the present disclosure are best understood from the following detailed description and by reading the accompanying drawings. It should be noted that the various features are not necessarily drawn to scale. In fact, the size and geometric dimensions of the various features may be arbitrarily enlarged or reduced for clarity of illustration.

[0008] Figure 1 A schematic diagram of an EUV lithography system with a laser generated plasma EUV radiation source is shown.

[0009] Figure 2 A schematic diagram of an extreme ultraviolet lithography exposure tool is shown.

[0010] Figure 3A as well as Figure 3B An optical system of an extreme ultraviolet radiation source for producing a pattern of light and dark fringes according to some embodiments of the present disclosure is shown.

[0011] Figure 4 An optical system of an extreme ultraviolet radiation source for producing a pattern of light and dark fringes according to some embodiments of the present disclosure is shown.

[0012] Figure 5 Shown is a pattern of light and dark fringes produced by an optical system according to some embodiments of the present disclosure.

[0013] Fig. 6A as well as Figure 6B An extreme ultraviolet radiation source for generating plasma from multiple droplets using multiple stripes is shown in accordance with some embodiments of the present disclosure.

[0014] Fig. 7A as well as Figure 7B An EUV radiation source for producing EUV radiation from a plurality of droplets is shown according to some embodiments of the present disclosure.

[0015] Figure 8 An exemplary EUV lithography system for producing EUV radiation from a plurality of droplets according to some embodiments of the present disclosure is schematically illustrated.

[0016] Fig.9A as well as Fig. 9B A flow chart is shown of an exemplary process for generating extreme ultraviolet radiation from a plurality of droplets according to some embodiments of the present disclosure.

[0017] Fig. 10A as well as Fig. 10B A computer system is shown of an apparatus for generating extreme ultraviolet radiation from a plurality of droplets according to some embodiments of the present disclosure.

[0018] The reference numerals are as follows:

[0019] 23: Plasma plume

[0020] 24: Extreme ultraviolet rays

[0021] 27: Microdrops

[0022] 29: Arrow

[0023] 50,142,148: Open

[0024] 85: Droplet Catcher

[0025] 100: Extreme ultraviolet radiation source

[0026] 105: Chamber

[0027] 110:Collection Mirror

[0028] 115: Droplet Generator

[0029] 117: Nozzle

[0030] 130: First buffer gas supplier

[0031] 132: Gas Flow

[0032] 135: Second buffer gas supply source

[0033] 140: Gas outlet

[0034] 146:Wall

[0035] 200: Exposure device

[0036] 205a, 205b, 205d, 205e: optical element

[0037] 205c: Reflective mask

[0038] 210:Semiconductor substrate

[0039] 300: Laser source

[0040] 310: Laser Generator

[0041] 330: Focusing Equipment

[0042] 400: Optical system

[0043] 504: Mirror system

[0044] 506,512,606: Laser beam / laser beam pair

[0045] 508: Reflector

[0046] 510: Beam splitter

[0047] 519,554: Width

[0048] 520,535: Pattern of light and dark stripes

[0049] 521: Middle Line

[0050] 522,530: Slit / Slit Pair

[0051] 523: Curve

[0052] 525: Length

[0053] 527,537: Stripes / Light Stripes

[0054] 531: Poor travel path

[0055] 532,536:Distance

[0056] 533: Dark Stripes

[0057] 534,552: Length

[0058] 538: Line

[0059] 540,546: Path

[0060] 544: Vertical Line

[0061] 610A, 610B, 610C, 610D, 810: Droplet lighting module

[0062] 620A, 620B, 620C, 620D, 820: Droplet detection module

[0063] 640: Illuminating radiation beam

[0064] 645:Reflection beam

[0065] 650: Extreme Ultraviolet Source

[0066] 800: Extreme Ultraviolet Lithography System

[0067] 830:Analyzer module

[0068] 840: Controller

[0069] 900,950: Technology

[0070] S910,S920,S930,S940,S952,S954,S956,S958,S960,S962: Operation

[0071] 1000:Computer Systems

[0072] 1001:Computer

[0073] 1002:Keyboard

[0074] 1003: Mouse

[0075] 1004: Monitor

[0076] 1005: CD-ROM drive

[0077] 1006:Disk drive

[0078] 1011: Processor

[0079] 1012: Read-only memory

[0080] 1013: Random Access Memory

[0081] 1014: Hard disk

[0082] 1015: Bus

[0083] 1021: CD

[0084] 1022: Disk

[0085] A,B,C:Point

[0086] BF: Ground floor

[0087] DP: Droplet

[0088] DMP1, DMP2: Damper

[0089] LR0,LR1,LR2:Laser beam

[0090] MF: Main Floor

[0091] PP1,PP2: Base plate

[0092] ZE: Excitation zone DETAILED DESCRIPTION

[0093] The following disclosure provides a variety of different embodiments or examples to implement the different features of the present disclosure. The following describes specific examples of various components and arrangements to simplify the present disclosure. Of course, these are only examples and are not intended to be limiting. For example, if the specification describes that a first feature is formed on a second feature, it means that an embodiment in which the first feature is in direct contact with the second feature may be included, and an embodiment in which an additional feature is formed between the first feature and the second feature so that the first feature and the second feature are not in direct contact may be included. In addition, in various examples, the present disclosure may use repeated reference symbols and / or letters. Such repetition is for the purpose of simplicity and clarity and does not represent the relationship between the various embodiments and / or configurations discussed.

[0094] In addition, spatially relative terms, such as "below", "below", "lower", "above", "higher", and the like, may be used herein to facilitate describing the relationship between one element or feature and another element or features in the drawings. These spatially relative terms are intended to cover different orientations of the device in use or operation in addition to the orientation shown in the drawings. The device can be turned to different orientations (rotated 90 degrees or other orientations), and the spatially relative terms used herein should be interpreted accordingly. In addition, the term "made of" can mean "including" or "consisting of". In the present disclosure, the sentence "one of A, B and C" means "A, B and / or C" (A, B, C, A and B, A and C, B and C, or A, B and C), unless otherwise specified, it does not mean one element from A, one element from B, and one element from C.

[0095] The extreme ultraviolet radiation source includes a laser source, a collecting mirror, a droplet generator, and a droplet catcher. In some embodiments, the droplet generator includes a plurality of nozzles, and simultaneously generates a plurality of target droplets of two, four, six, eight, or ten droplets in parallel. In some embodiments, the size of the plurality of droplets is relatively small, so less laser energy is required to be ionized to generate extreme ultraviolet radiation. In some embodiments, the high-power laser beam is divided into a plurality of parts, for example, into two, three, or four parts, and is introduced into the extreme ultraviolet radiation source via a plurality of slits (e.g., openings), and from a plurality of directions (e.g., via two, three, or four slits), and from two, three, or four directions. The plurality of parts of the laser beam may interfere at an excitation region in the extreme ultraviolet radiation source, and a plurality of parallel laser stripes may be generated at the excitation region. In some embodiments, the width of the plurality of stripes is comparable to the width of the smaller droplets, and the plurality of nozzles of the droplet generator release the droplets so that each droplet travels along one of the plurality of parallel stripes. As the droplet passes through each stripe (e.g., along the stripe), the laser energy of the stripe can free the droplet to generate extreme ultraviolet radiation. Although the laser energy / power is divided into multiple stripes, and thus the energy / power of each stripe is smaller than when the laser beam is focused on one point, because the surface area of ​​multiple smaller droplets is greater than the surface area of ​​a large droplet, the large droplet has the size of a combination of smaller droplets, and thus the efficiency of generating extreme ultraviolet radiation may be higher. Therefore, more laser energy can be transferred to smaller droplets than when the laser beam is focused on one point of the large droplet. In addition, the laser stripe has a length such that the smaller droplets pass along the length of the stripe, and therefore stay under the laser beam for a longer time than when the laser beam is focused on one point of the large droplet. Therefore, the efficiency of generating extreme ultraviolet radiation can be further improved.

[0096] Figure 1 Schematic diagram of an EUV lithography system with a laser generated plasma EUV radiation source is shown. The EUV lithography system includes an EUV radiation source 100 (EUV light source) that generates EUV radiation, an exposure device 200 (eg, a scanner), and an excitation laser source 300. Figure 1 As shown, in some embodiments, the extreme ultraviolet radiation source 100 and the exposure device 200 are installed in the main floor MF of the clean room, and the excitation laser source 300 is installed in the base floor BF located below the main floor MF. The extreme ultraviolet radiation source 100 and the exposure device 200 are placed on the base plates PP1 and PP2 via dampers DMP1 and DMP2, respectively. The extreme ultraviolet radiation source 100 and the exposure device 200 are coupled to each other through a coupling mechanism, and the coupling mechanism may include a focusing unit.

[0097] The photolithography system is an EUV lithography system designed to expose a photoresist layer by EUV light (also interchangeably referred to herein as EUV radiation). The photoresist layer is a material that is sensitive to EUV light. The EUV lithography system uses an EUV radiation source 100 to generate EUV light, for example, EUV light having a wavelength ranging from about 1 nanometer to about 100 nanometers. In a specific example, the EUV radiation source 100 generates EUV light having a wavelength centered at about 13.5 nanometers. In the present embodiment, the EUV radiation source 100 generates EUV radiation using a laser-generated plasma mechanism.

[0098] The exposure device 200 includes various reflective optical components, such as convex / concave / flat mirrors, a mask holding mechanism including a mask carrier, and a wafer holding mechanism. The extreme ultraviolet radiation generated by the extreme ultraviolet radiation source 100 is guided by the reflective optical components to the mask fixed on the mask carrier. In some embodiments, the mask carrier includes an electrostatic suction seat (e-chuck) for fixing the mask. Since gas molecules absorb extreme ultraviolet light, the lithography system used for extreme ultraviolet lithography patterning is maintained in a vacuum or low-pressure environment to avoid extreme ultraviolet intensity loss. Figure 2 The exposure device 200 is described in more detail in FIG.

[0099] In the present disclosure, the terms mask, photomask, and reticle are used interchangeably. In some embodiments, the mask is a reflective mask. In some embodiments, the mask includes a substrate having a suitable material, such as a low thermal expansion material or fused quartz. In various examples, the material includes titanium dioxide (TiO2) doped with silicon dioxide (SiO2), or other suitable materials with low thermal expansion. The mask includes a plurality of reflective layers (ML) deposited on the substrate. The reflective layer includes a plurality of film pairs, such as molybdenum silicon (Mo / Si) film pairs (e.g., each film pair has a layer of molybdenum above or below a layer of silicon). Alternatively, the reflective layer may include a molybdenum beryllium (Mo / Be) film pair, or other suitable materials that can be configured to highly reflect extreme ultraviolet light. The mask may also include a capping layer for protection disposed above the reflective layer, such as ruthenium (Ru). The mask also includes an absorption layer deposited above the reflective layer, such as a tantalum boron nitride (TaBN) layer. The absorption layer is patterned to define a layer of an integrated circuit (IC). Alternatively, another reflective layer may be deposited over the reflective layer and patterned to define a layer of an integrated circuit, thereby forming an extreme ultraviolet phase shift mask (EUV phase shift mask).

[0100] The exposure device 200 includes a projection optical element module, which is used to image the pattern of the mask onto a semiconductor substrate, which is coated with photoresist and fixed on a substrate stage of the exposure device 200. The projection optical element module generally includes a reflective optical element. The extreme ultraviolet radiation (EUV light) guided from the mask carries the image of the pattern defined on the mask and is collected by the projection optical element module, thereby forming an image on the photoresist.

[0101] In various embodiments of the present disclosure, the semiconductor substrate is a semiconductor wafer, such as a patterned silicon wafer or other type of wafer. In an embodiment of the present disclosure, the semiconductor substrate is coated with a photoresist layer that is sensitive to extreme ultraviolet light. The various components included above are integrated together and can be operated to perform a photolithography exposure process. The photolithography system may also include other modules, or be integrated (or coupled) with other modules.

[0102] like Figure 1 As shown, the extreme ultraviolet radiation source 100 includes a droplet generator 115 surrounded by a chamber 105 and a laser generated plasma collecting mirror 110. Non-interacting droplets DP reach a droplet catcher 85. The droplet generator 115 generates a plurality of target droplets DP, which are supplied into the chamber 105 via a nozzle 117. In some embodiments, the target droplets DP are metal droplets such as tin (Sn), lithium (Li), or an alloy of tin and lithium. Although in Figure 1 Although not shown in the cross-sectional view of FIG. 1 , in some embodiments, the droplet generator 115 generates multiple target droplets DP simultaneously and in parallel. Fig. 6A as well as Figure 6BAs will be described, the nozzle 117 of the droplet generator 115 has a plurality of openings that generate a plurality of target droplets DP in parallel (e.g., parallel target droplets DP). In some embodiments, each target droplet DP has a diameter in the range of about 10 microns (μm) to about 50 microns. For example, in some embodiments, the target droplets DP are tin droplets, each having a diameter of about 10 microns to about 22 microns. In some embodiments, the target droplets DP are supplied via the plurality of openings of the nozzle 117 at a rate of from about 50 droplets per second (i.e., a jetting frequency of about 50 Hz) to about 50,000 droplets per second (i.e., a jetting frequency of about 50 kHz). For example, in some embodiments, the target droplets DP are supplied at a jetting frequency of about 50 Hz, about 100 Hz, about 500 Hz, about 1 kHz, about 10 kHz, about 25 kHz, about 50 kHz, or any frequency between these frequencies. In various embodiments, the target droplets DP are ejected into the excitation zone ZE (e.g., the target droplet location) through the plurality of openings of the nozzle 117 at a speed ranging from about 10 meters per second (m / s) to about 100 meters per second. For example, in some embodiments, the target droplets DP have a speed of about 10 meters per second, about 25 meters per second, about 50 meters per second, about 75 meters per second, about 100 meters per second, or any speed between these speeds. Although in Figure 1 Not shown in the cross-sectional view, but in some embodiments, the droplet catcher 85 receives a plurality of parallel droplets DP that do not interact with the laser beam LR2. Fig. 6A as well as Figure 6B A droplet catcher 85 is shown, which receives a plurality of target droplets DP without interaction. Fig. 6A as well as Figure 6B As will be described, the nozzle 117 of the droplet generator 115 generates a plurality of target droplets DP (e.g., parallel target droplets DP) in parallel. The diameter of the parallel target droplets DP may be in the range of about 10 microns to about 22 microns. In various embodiments, the parallel target droplets DP are ejected through the nozzle 117 at a speed in the range of about 10 meters per second to about 100 meters per second and enter the excitation region ZE.

[0103] The excitation laser source 300 generates an ionizing laser beam LR2, which is a pulsed beam in some embodiments. The laser pulses of the ionizing laser beam LR2 are generated by the excitation laser source 300. The excitation laser source 300 may include a laser generator 310, a laser guiding optical element 320, and a focusing device 330. In some embodiments, the laser generator 310 includes a carbon dioxide (CO2) or a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser source, the wavelength of which is in the infrared region of the electromagnetic spectrum. For example, in some embodiments, the laser generator 310 has a wavelength between 8 microns and 15 microns. The laser beam LR0 generated by the excitation laser source 300 is guided by the laser guiding optical element 320 and focused into the ionizing laser beam LR2 by the focusing device 330, and the ionizing laser beam LR2 is introduced into the extreme ultraviolet radiation source 100. In some embodiments, in addition to carbon dioxide and Nd:YAG lasers, the ionizing laser beam LR2 can be generated by a gas laser or a solid-state laser, and the gas lasers include excimer gas discharge lasers, helium-neon lasers, nitrogen lasers, transversely excited atmospheric (TEA) lasers, argon ion lasers, copper vapor lasers, krypton fluorine (KrF) lasers, or argon fluorine (ArF) lasers. Solid-state lasers include neodymium glass lasers, ytterbium-doped glass or ceramic lasers, or ruby ​​lasers. In some embodiments, the excitation laser source 300 also generates a non-ionizing laser beam LR1, and the focusing device 330 also focuses the non-ionizing laser beam LR1. In some embodiments, as described with respect to Fig. 6A as well as Figure 6B As will be described, the ionizing laser beam LR2 is divided into two parts of the laser beam LR2, and the two parts of the laser beam LR2 reach the excitation region ZE from two different angles and thus interact at the excitation region ZE to generate a first plurality of parallel bright stripes at the excitation region ZE. At the excitation region ZE, each of the parallel target droplets DP interacts in parallel with one of the first plurality of parallel bright stripes to be ionized and generate extreme ultraviolet radiation.

[0104] In some embodiments, the laser source 300 generates the ionizing laser beam LR2 and the non-ionizing laser beam LR1 as pulses. In such embodiments, the non-ionizing laser beam LR1 is a preheating laser pulse (interchangeably referred to herein as a "pre-pulse") that is used to heat (or preheat) a given target droplet to produce a low-density target plume with multiple smaller droplets, which is then heated (or reheated) by a pulse (e.g., a main pulse) from the ionizing laser beam LR2, resulting in increased extreme ultraviolet light emission compared to when no preheating laser pulse is used.

[0105] In some embodiments, such as regarding Fig. 6A as well as Figure 6B As will be described, the non-ionized laser beam LR1 is also divided into two parts of the non-ionized laser beam LR1, and the two parts of the non-ionized laser beam LR1 arrive at a position slightly before the excitation area ZE from two different angles, thereby interacting at a position slightly before the excitation area ZE to generate a second group of multiple parallel bright stripes. In some embodiments, as described with respect to Fig. 6A as well as Figure 6B As will be described, each of the parallel target droplets DP interacts with one of the second plurality of parallel bright stripes to be heated and produce a low-density target plume before reaching the excitation zone ZE. As noted, in some embodiments, the laser source 300 generates laser beams LR1 and LR2. Laser beam LR1 generates the second plurality of parallel bright stripes, and laser beam LR2 generates the first plurality of parallel bright stripes. In some embodiments, the laser source 300 includes a laser source for generating laser beam LR2, and also includes another laser source for generating laser beam LR1. In some embodiments, laser beam LR0 includes a non-ionizing laser and an ionizing laser generated by the excitation laser source 300 and the laser generator 310. In some embodiments, as described with respect to Figure 3B as well as Figure 7B As described, the laser guiding optical element 320 and the focusing device 330 send the ionized laser beam LR2 and the non-ionized laser beam LR1 to the excitation region ZE via the separated slit pairs in the collecting mirror 110 to generate a first group of multiple parallel bright stripes and a second group of multiple parallel bright stripes. The second group of multiple parallel bright stripes is generated on top of the first group of multiple parallel bright stripes.

[0106] In various embodiments, the preheating non-ionizing laser beam LR1 generates a second plurality of parallel bright stripes, the width of the second plurality of parallel bright stripes is between about 300 microns and about 500 microns, and the ionizing laser beam LR2 generates a first plurality of parallel bright stripes, the width of the first plurality of parallel bright stripes is between about 300 microns and about 500 microns. In some embodiments, the pulse duration of the preheating non-ionizing laser beam LR1 and the ionizing laser beam LR2 is in the range of about 10 nanoseconds to about 50 nanoseconds, and the pulse frequency is in the range of about 1 kHz to about 100 kHz. In various embodiments, the average power of the preheating laser and the excitation laser is in the range from about 1 kilowatt (kW) to about 50 kilowatts. In some embodiments, the pulse frequencies of the non-ionizing laser beam LR1 and the ionizing laser beam LR2 match the ejection frequency of the target droplet DP.

[0107] The ionizing laser beam LR2 is directed to the excitation region ZE via an opening (or lens). The opening is made of a suitable material that is substantially transparent to the laser beam. The generation of the laser pulse is synchronized with the ejection of the target droplet DP via the nozzle 117. As the target droplet moves through the excitation region, the pre-pulse heats the target droplet and transforms it into a low-density target plume. The delay between the pre-pulse of the non-ionizing laser beam LR1 and the main pulse of the ionizing laser beam LR2 is controlled to allow the target plume to form and expand to an optimal size and geometry. In various embodiments, the pre-pulse and the main pulse have the same pulse duration and peak power. When the main pulse heats the target plume, a high-temperature plasma is generated. The plasma emits extreme ultraviolet radiation, which is collected by the collecting mirror 110. The collecting mirror 110 (extreme ultraviolet collecting mirror) further reflects and focuses the extreme ultraviolet radiation for use in a photolithography exposure process performed via the exposure device 200. In some embodiments, as described with respect to Figure 3A , Figure 3B , Figure 4 as well as Figure 5 As will be described, the opening can be one or more pairs of slits, so that the two parts of the non-free laser beam LR1 and / or the two parts of the free laser beam LR2 enter from a pair of slits. As described, in some embodiments, the interaction of the two parts of the free laser beam LR2 generates a first plurality of parallel bright stripes at the excitation region ZE, and the interaction of the two parts of the non-free laser beam LR1 generates a second plurality of parallel bright stripes slightly before the excitation region ZE.

[0108] One method of synchronizing the generation of pulses (either pre-pulses and main pulses or both) from the excitation laser with the arrival of a target droplet in the excitation region ZE is to detect the passage of a target droplet at a given position and use it as a signal to trigger the excitation pulse (or pre-pulse). In this method, for example, if the passage time of the target droplet is denoted by t0, and the time of generation (and detection) of the EUV radiation is denoted by t rad Represented by, and the distance between the position where the target droplet passes and the center of the excitation area is detected as d, then the velocity v of the target droplet dp Calculated as

[0109] v dp =d / (t rad -t0)–Equation (1).

[0110] Since it is desirable for the droplet generator 115 to reproducibly provide droplets at a fixed rate, once v is calculated dp , after detecting that the target droplet has passed a given position, d / v dp The excitation pulse is triggered with a time delay of t to ensure that the excitation pulse arrives at the same time as the target droplet reaches the center of the excitation region. In some embodiments, because the passage of the target droplet is used to trigger the pre-pulse, the main pulse is triggered after a fixed delay of the pre-pulse. In some embodiments, if necessary, by periodically measuring t rad To periodically recalculate the target droplet velocity v dp The value of , and resynchronizes the arrival of the target droplet with the generation of the pulse. Fig. 6A as well as Figure 6B Described herein are the timing and duration of the pre-pulse and / or main pulse when generating the first group and / or the second group of multiple parallel bright stripes.

[0111] like Figure 1As shown, a buffer gas is supplied from a first buffer gas supply 130 via an opening in the collecting mirror 110, through which the ionized laser beam LR2 and / or the non-ionized laser beam LR1 are transmitted to the tin droplets. In some embodiments, the buffer gas is hydrogen (H2), helium (He), argon (Ar), nitrogen (N) or another inert gas. In some embodiments, hydrogen is used as a buffer gas because hydrogen radicals generated by the ionization of the buffer gas can be used for cleaning purposes. Buffer gas can also be provided toward the collecting mirror 110 and / or around the edge of the collecting mirror 110 by one or more second buffer gas supply sources 135. In addition, the chamber 105 includes one or more gas outlets 140 so that the buffer gas is discharged to the outside of the chamber 105. Hydrogen has low absorption of extreme ultraviolet radiation. The hydrogen reaching the coating surface of the collecting mirror 110 reacts chemically with the metal of the droplet to form a hydride, for example, a metal hydride. When tin (Sn) is used as a droplet, stanane (SnH4) which is a gaseous byproduct of the extreme ultraviolet generation process is formed. The gaseous stannane is then pumped out through gas outlet 140. However, it is difficult to exhaust all of the gaseous stannane from the chamber, and it is difficult to prevent the stannane from entering exposure apparatus 200. Therefore, monitoring and controlling debris in EUV radiation source 100 is beneficial to the performance of the EUV lithography system.

[0112] Figure 2 A schematic diagram of an extreme ultraviolet lithography exposure tool is shown. Figure 2 The extreme ultraviolet lithography exposure machine includes an exposure device 200, which shows the exposure of a substrate coated with photoresist (target semiconductor substrate 210) with a patterned beam of extreme ultraviolet light. The exposure device 200 is an integrated circuit lithography machine, such as a stepper, a scanner, a step and scan system, a direct write system, a device using a contact and / or proximity mask, etc., and provides one or more optical elements 205a, 205b, for example, irradiating a patterned optical element (such as a reduction mask, for example, a reflective mask 205c) with an extreme ultraviolet beam to generate a patterned beam, and one or more reduction projection optical elements 205d, 205e, for projecting the patterned beam onto the target semiconductor substrate 210. A mechanical component (not shown) can be provided to generate a controllable relative movement between the target semiconductor substrate 210 and the patterned optical element (for example, the reflective mask 205c). As further shown, Figure 2The EUV lithography exposure tool further includes an EUV radiation source 100, which includes a plasma plume 23 emitting EUV light at an excitation region ZE in a chamber 105. The EUV light is collected by a collecting mirror 110 and reflected into an exposure device 200 to irradiate a target semiconductor substrate 210. In some embodiments, the first group and the second group of multiple parallel bright stripes are arranged in a Figure 2 The excitation region ZE is in a small area of ​​about 500 microns by about 500 microns, and the collecting mirror 110 is adjusted so that the extreme ultraviolet radiation generated in the extreme ultraviolet radiation source 100 is collected and focused by the collecting mirror 110, and is transmitted to one or more optical elements 205a, 205b outside the extreme ultraviolet radiation source 100.

[0113] Figure 3A as well as Figure 3B An optical system of an extreme ultraviolet radiation source for producing a pattern of light and dark stripes according to some embodiments of the present disclosure is shown. In some embodiments, Figure 3A The optical system 350 Figure 1 The method is implemented in the extreme ultraviolet radiation source 100 , and a pattern of bright and dark stripes is generated in the excitation region ZE of the extreme ultraviolet radiation source 100 using the laser beam LR0 generated by the excitation laser source 300 .

[0114] Figure 3A A plan view of the optical system 350 in the XY plane is shown. The optical system 350 receives and Figure 1 The laser beam 512 is consistent with the laser beam LR0. The laser beam 512 enters the mirror system 504, which includes a beam splitter 510 and three mirrors 508 (e.g., 45-degree mirrors). The mirror system 504 splits the laser beam 512 into two laser beams 506, i.e., a laser beam pair 506, which have similar (e.g., substantially equal) intensities. The laser beam pair 506 passes through the slit pair 522 in the collecting mirror 110 and produces a pattern 520 of bright and dark stripes, which has stripes 527 in the excitation region ZE in front of the slit 522 in the XZ plane. Figure 3A As shown, the laser beam pair 506 does not travel the same distance to reach the excitation region ZE, and therefore, the bright fringe 527 may not appear at the center line 521 (eg, the symmetry line) between the slit pair 522. In some embodiments, the laser beam 512 and the Figure 1 In some embodiments, laser beam 512 is consistent with laser beam LR2 or laser beam LR1. Fig. 6A , Figure 6B , Fig. 7A as well as Figure 7B The laser beam 506 or the laser beam 606 is consistent.

[0115] In some embodiments, Figure 3A As shown, a delay segment 502 is introduced in the path of one of the laser beams 506 to produce a delay in one of the laser beams 506 and thereby move the bright and dark stripes. In some embodiments, the delay segment 502 produces a delay so that the laser beams 506 are in-phase and thereby produce a bright stripe 527 at a center line 521 in the excitation region ZE. In some embodiments, the delay segment 502 produces a delay so that the laser beams 506 are 180 degrees out of phase and thereby produce a dark stripe 533 at a center line 521 in the excitation region ZE. In some embodiments, the slit pair 522 is a rectangular opening in the collecting mirror 110. In some embodiments, the distance 536 between the centers of the slits 522 in the X direction is between about 0.5 mm and about 10 mm. About Figure 3B The slits are described in more detail. Figure 3A As shown, the collecting mirror 110 is a cross section of the collecting mirror, so the pattern 520 of bright and dark stripes is perpendicular to Figure 3A The XY plane extends in the Z direction.

[0116] Figure 3B Two slit pairs 522 and 530 in the collector mirror 110 are shown. Figure 3Bis a plan view of the collector mirror 110 perpendicular to the Y direction. As shown, the slit pair 530 is arranged on top of the slit pair 522 in the Z direction. As described, the collector mirror 110 can have an elliptical or parabolic shape to guide the extreme ultraviolet radiation generated from the extreme ultraviolet radiation source 100. In some embodiments, each slit in the slit pair has a rectangular shape with a width 554 and a length 552, and the centers of the slits are separated by a distance 536 in the X direction. In some embodiments, the slits of each slit pair have similar shapes and sizes, while the slits of the slit pair 522 have different shapes and / or sizes from the slits of the slit pair 530. In some embodiments, the laser beam LR2 is split into a laser beam pair by the mirror system 504, and the pair of laser beams passes through the slit pair 522 and produces a pattern of light and dark stripes in the excitation region ZE. In some embodiments, the laser beam LR1 is split into a laser beam pair by another mirror system (not shown), and the pair of laser beams passes through the slit pair 530 and produces a pattern of light and dark stripes in the excitation region ZE. In some embodiments, laser beam LR2 generates a first pattern of light and dark stripes in excitation region ZE, and laser beam LR1 generates a second pattern of light and dark stripes in excitation region ZE, the second pattern of light and dark stripes being on top of the first pattern of light and dark stripes. Thus, two non-overlapping patterns of light and dark stripes can be generated on top of each other by laser beams LR1 and LR2 at excitation region ZE. In some embodiments, distance 536 is between about 0.5 mm and about 10 mm. Width 554 is between about 200 nanometers and about 10 microns, and length 552 is between about 100 microns and about 1 mm. In some embodiments, length 552 and width 554 of slit pair 522 and slit pair 530 are the same, however, because the wavelengths of laser beams LR1 and LR2 are different, distance 536 between the two slit pairs 522 and 530 is not the same. In some embodiments, the distance 536 between the slits in the slit pair 530 is adjusted by the ratio of the wavelengths of the laser beams LR2 and LR1, so that the first group and the second group of multiple parallel bright stripes generated by the laser beams LR2 and LR1 both have the same effective width and the same effective distance between adjacent stripes.

[0117] Figure 4 An optical system of an extreme ultraviolet radiation source for producing a pattern of light and dark fringes according to some embodiments of the present disclosure is shown. Figure 4 Shows the reception Figure 3A The optical system 400 includes a laser beam 506. The laser beam 506 enters the slit 522 in the collecting mirror 110 and generates a pattern 520 of light and dark stripes along the X direction above the line 538 at the excitation region ZE. The intensity variation of the pattern 520 of light and dark stripes is shown by the curve 523. In some embodiments, as Figure 4As shown, curve 523 has a maximum value and a minimum value. Curve 523 has a maximum value at point A where the center line 521 intersects the line 538 at the excitation region ZE. In some embodiments, the laser beam 506 entering the slit pair 522 is in phase, so the beams arriving at point A from the slit pair 522 remain in phase and constructively add at point A to produce a maximum value. In some embodiments, the distance 536 between the slits is between 200 nanometers and 100 centimeters. In some embodiments, the slit pair 522 is adjacent to each other, and the angle θ between the incident beams is between 0.5 and 5 degrees. In some embodiments, the slits 522 are on opposite sides of the collecting mirror 110, and the angle θ between the incident beams is between 175 degrees and 179.5 degrees.

[0118] Similarly, laser beam 506 entering slit pair 522 travels along paths 546 and 540 to reach point B of line 538 at excitation region ZE. In some embodiments, paths 546 and 540 have a travel path difference 531, which is Figure 4 540 is shown in the figure by a vertical line 544 from the upper slit 522 to the path 540. The travel path difference 531 is equal to one or more wavelengths, for example one wavelength, of the laser beam 506. Therefore, the light beams arriving at point B from the slit pair 522 remain in phase at point B and constructively add to produce a maximum value at point B. In some embodiments, the length 534 between point A and point B is equal to the wavelength of the laser beam 506 multiplied by the ratio of distance 532 to distance 536. Distance 532 is the distance between the collecting mirror 110 and the excitation region ZE in the Y direction, and distance 536 is the distance of the slit 522 of the collecting mirror 110 in the X direction. Conversely, the laser beam 506 entering the slit pair 522 is destructively added at point C between point A and point B, thereby producing a minimum value at point C. In some embodiments, as Figure 4 As shown, curve 523 has a cosine square shape, and as shown, bright fringe 527 is centered at the maximum point of curve 523, while dark fringe 533 is centered at the minimum point of curve 523.

[0119] Figure 5 Shown is a pattern of light and dark fringes produced by an optical system according to some embodiments of the present disclosure. Figure 5 A pattern of light and dark stripes 520 is shown in the excitation region ZE, and also light stripes 527 and dark stripes 533 are shown. In some embodiments, the pattern of light and dark stripes 520 extends along a line 538 in the X direction with a width 519. In some embodiments, each stripe of the pattern of light and dark stripes 520 extends along a line perpendicular to the line 538 (e.g., in the Z direction) with a length 525. Figure 4As shown, the length 534 is the sum of the widths of the bright stripes 527 and the dark stripes 533, and therefore, the width of each of the bright stripes 527 and the width of each of the dark stripes 533 is half of the length 534. In some embodiments, as the bright stripes 527 are further away from the center of the pattern of bright and dark stripes 520, the length of the bright stripes 527 is reduced. In some embodiments, when the slit 522 has a rectangular shape in the XZ plane, the pattern of bright and dark stripes 520 has a two-dimensional sinc-function envelope in the XZ plane at the excitation region ZE. Therefore, in some embodiments, the pattern of bright and dark stripes 520 is a two-dimensional cosine square function that varies in the X direction and is limited by the main lobe of the two-dimensional sinc function. In some embodiments, the length 525 of the stripes decreases as the stripes are away from the central stripes. Therefore, the stripes away from the central stripes do not have an effective length so that when the droplet DP passes through the stripes, sufficient energy of the laser beam LR1 or LR2 is transferred to the droplet DP. Therefore, the length 525 of the stripes defines the number of parallel droplets that pass through the stripes at the same time.

[0120] In some embodiments, the width 519 of the pattern of light and dark stripes 520 is inversely proportional to the width 554 of the slit pair 522, and the length 525 of the pattern of light and dark stripes 520 is inversely proportional to the length 552 of the slit pair 522. In some embodiments, the two-dimensional sinc function has other lobes with smaller intensities in the X direction and the Z direction, and thus the other patterns of light and dark stripes are repeated with smaller intensities to the right, left, above, and below the pattern of light and dark stripes 520, and at least a portion of the other patterns of light and dark stripes is invisible. In some embodiments, the frequency of the stripes of the pattern of light and dark stripes 520 (e.g., the frequency of the cosine square function) is proportional to the distance 536 between the centers of the slit pair 522. In some embodiments, the stripes in the lobe between the droplet generator 115 and the pattern of light and dark stripes 520 are used to preheat the droplet DP.

[0121] Fig. 6A as well as Figure 6B An extreme ultraviolet radiation source for generating plasma from multiple droplets using multiple stripes is shown in accordance with some embodiments of the present disclosure. Fig. 6A as well as Figure 6B A droplet generator 115 is shown having a nozzle 117 which generates a plurality of droplets DP simultaneously and in parallel. Fig. 6A Shows the passage through Figure 3A The non-free laser beam LR1 of the reflector system consistent with the reflector system 504 is generated by the laser beam pair 606. In addition, the laser beam pair 606 passes through the Figure 3BThe slit pair 530 of FIG. 5 is consistent with the slit pair 530 of FIG. 5 and generates a light-dark stripe pattern 535 having stripes 537 at the excitation region ZE. When reaching the excitation region ZE, the plurality of parallel droplets DP pass through the light-dark stripe pattern 535 and thus a flat pancake-shaped droplet 27 is generated from each of the plurality of droplets DP. Fig. 6A As shown, each of the plurality of droplets DP passes through one of the bright stripes 537 of the pattern 535 of bright and dark stripes.

[0122] Fig. 6A It also shows the Figure 3A The free laser beam LR2 of the reflector system consistent with the reflector system 504 is generated by the laser beam pair 506. In addition, the laser beam pair 506 passes through the Figure 3B The slit pair 522 of the EUV lithography system is consistent with the slit pair 522 of the EUV lithography system, and a pattern 520 of bright and dark stripes is generated at the excitation region ZE. The oval-shaped droplet 27 passes through the pattern 520 of bright and dark stripes, so that each oval-shaped droplet 27 passes through one of the bright stripes 527 of the pattern 520 of bright and dark stripes. Each oval-shaped droplet 27 that passes through the bright stripe 527 interacts with the bright stripe 527 at the excitation region ZE in the chamber of the EUV lithography system to form a plasma plume 23, and the plasma plume 23 emits EUV rays 24 in all directions. In some embodiments, a plurality of droplets DP are simultaneously interacted by a plurality of bright stripes 527 at the excitation region ZE, and the plurality of bright stripes 527 are generated by the ionizing laser beam LR2 to generate a plasma plume 23 that emits EUV rays 24 in all directions.

[0123] Figure 6B shows the Figure 3B The laser beam pair 506 is aligned with the slit pair 522 of the slit pair 522, and generates a pattern of bright and dark stripes 520 at the excitation region ZE. A plurality of droplets DP pass through the pattern of bright and dark stripes 520, so that each droplet DP passes through one of the bright stripes 527 of the pattern of bright and dark stripes 520. Passing through the bright stripes 527, the droplet DP interacts with the bright stripes 527 at the excitation region ZE in the chamber of the EUV lithography system to form a plasma plume 23 that emits EUV light rays 24 in all directions.

[0124] like Fig. 6A as well as Figure 6B As shown, each of the plurality of droplets DP receives laser energy when passing through the bright stripes, and thus is connected to the droplet DP in Figure 1 The amount of time the laser energy is received is longer than the amount of time the laser energy is received in the extreme ultraviolet radiation source 100 of FIG. Fig. 6A as well as Figure 6BIn the embodiment of the present invention, the ionizing laser beam LR2 is divided into a plurality of stripes, and by irradiating a plurality of droplets DP at the same time and receiving the laser energy for a longer time, in terms of converting the laser energy into extreme ultraviolet radiation, Fig. 6A as well as Figure 6B The efficiency of the extreme ultraviolet radiation source is greater than Figure 1 The efficiency of the extreme ultraviolet radiation source is 100.

[0125] In some embodiments, Figure 6B As shown in FIG. 6 , one or more droplet illumination modules (DIM) 610A, 610B, 610C, or 610D illuminate the excitation region ZE with non-ionized light to illuminate the droplet DP. In addition, one or more droplet detection modules (DDM) 620A, 620B, 620C, or 620D capture an image of the excitation region ZE to determine (e.g., calculate) the speed of the plurality of droplets DP, and determine the timing of the laser pulse to generate the ionized laser beam LR2 and the timing of the non-ionized laser beam LR1 to generate a pattern of light and dark stripes 520 / 535, so that the plurality of droplets DP / flattened droplets 27 travel through the pattern of light and dark stripes 520 / 535, respectively. In some embodiments, the droplet illumination module 610A transmits the illumination radiation beam 640 to the excitation region ZE, and the droplet detection module 620A receives the reflected beam 645 from the excitation region ZE.

[0126] In some embodiments, the collector mirror 110 is modified (e.g., adjusted) so that an interaction of the plasma plumes 23 (emitting extreme ultraviolet rays 24 from each of the plurality of droplets DP) is generated in the excitation region ZE, and the extreme ultraviolet rays 24 are collected by the collector mirror 110 and directed to the exposure device 200. In some embodiments, a pattern 520 of bright and dark stripes appears in the excitation region ZE, and the excitation region ZE is at the focus of the collector mirror 110 or sufficiently surrounds the focus of the collector mirror 110. In some embodiments, the collector mirror 110 is adjusted to improve the efficiency of the collector mirror 110 for collecting and focusing the generated extreme ultraviolet radiation. In some embodiments, Figure 1 Compared with the size of the droplet DP, Fig. 6A as well as Figure 6B The size of the multiple droplets DP in Figure 1 Compared with the plasma plume of the microdroplet DP in 23 Fig. 6A as well as Figure 6BThe droplets in the plasma plume 23 use less laser energy. In some embodiments, as described above, the size of the plurality of droplets DP is between about 10 microns and about 22 microns. In some embodiments, the size and number of the plurality of parallel droplets DP are adjusted so that 250 watts of extreme ultraviolet radiation is generated.

[0127] Fig. 7A as well as Figure 7B An EUV radiation source for producing EUV radiation from a plurality of droplets according to some embodiments of the present disclosure is shown. Fig. 7A Shows Figure 1 Detail of a droplet generator 115 having a nozzle 117 that generates a plurality of droplets DP simultaneously (eg, in parallel) from a plurality of adjacent openings. Figure 3A The mirror system 504 of the collector mirror 110 is consistent with the mirror system 504, and the ionizing laser beam LR2 is divided into a laser beam pair 506. The laser beam pair 506 passes through the slit pair 522 of the collector mirror 110 and generates a pattern of bright and dark stripes 520 in the XZ plane in the excitation area ZE in front of the slit pair 522. A plurality of droplets DP pass through the plane of the pattern of bright and dark stripes 520, so that each droplet DP passes through a bright stripe 527 of the pattern of bright and dark stripes 520, which receives the laser beam energy from the bright stripe and generates a plasma plume 23 that generates extreme ultraviolet light rays 24 (extreme ultraviolet radiation). The droplet catcher 85 is configured to receive debris droplets associated with the plurality of droplets DP. In some embodiments, the collector mirror 110 collects the generated extreme ultraviolet light rays 24 and directs them to the opening 148 of the extreme ultraviolet radiation source 100. In some embodiments, the ionizing laser beam LR2 interacts with the tin droplets DP in the space between the collecting mirror 110 and the wall 146 of the extreme ultraviolet radiation source 100 at the excitation region ZE to form a plasma plume 23 that emits extreme ultraviolet light rays 24 in all directions. Wall 146 is used to create a cone shape so that the extreme ultraviolet radiation along arrow 29 inside the cone exits through opening 148, and any other radiation not along arrow 29 does not exit the cone, and therefore does not exit the extreme ultraviolet radiation source 100.

[0128] Figure 7B Also shown is a droplet generator 115 having a nozzle 117 that generates a plurality of droplets DP in parallel from a plurality of adjacent openings simultaneously. Figure 3A The mirror system 504 of the collector mirror 110 is consistent with the mirror system 504, and the ionizing laser beam LR2 is divided into a laser beam pair 506. The laser beam pair 506 passes through the slit pair 522 of the collector mirror 110 and generates a pattern 520 of bright and dark stripes in the XZ plane in the excitation region ZE in front of the slit pair 522. Figure 3AThe mirror system 504 of the collector mirror 110 is consistent with the mirror system 504, and the preheating non-ionizing laser beam LR1 is divided into a laser beam pair 606. The laser beam pair 606 passes through the slit pair 530 of the collector mirror 110 and generates a pattern 535 of bright and dark stripes in the XZ plane in front of the slit pair 530. In some embodiments, the pattern 535 of bright and dark stripes and the pattern 520 of bright and dark stripes do not overlap and appear in the same XZ plane in the excitation region ZE. In some embodiments, the opening 50 of the collector mirror 110 is used to allow the gas flow 132 to enter the extreme ultraviolet radiation source 100. In some embodiments, at least a portion of the gas flow 132 exits through the opening 142 in the conical wall 146.

[0129] As about Fig. 6A As described, the plurality of droplets DP pass through the plane of the pattern of bright and dark stripes 535 and 520, so that each droplet DP first passes through a bright stripe 537 of the pattern of bright and dark stripes 535, receives the laser beam energy from the bright stripe 537, and generates a pancake-shaped droplet 27. Then, each pancake-shaped droplet 27 passes through a bright stripe 527 of the pattern of bright and dark stripes 520, receives the laser beam energy from the bright stripe 527, and generates a plasma plume 23, which generates extreme ultraviolet light rays 24 (extreme ultraviolet radiation). Therefore, the plurality of droplets DP first pass through the bright stripe 537 of the pattern of bright and dark stripes 535, receive the preheating non-ionizing energy of the laser beam LR1, and generate pancake-shaped droplets 27. Then, the pancake-shaped droplet 27 passes through the bright stripe 527 of the pattern of bright and dark stripes 520, receives the ionizing energy of the laser beam LR2, and generates a plasma plume 23, which generates extreme ultraviolet light rays 24. In some embodiments, the collecting mirror 110 collects the generated extreme ultraviolet light rays 24 and directs them to the opening 148 of the extreme ultraviolet radiation source 100. In some embodiments, the size of the droplet DP, the number of parallel droplets DP, and the distance between parallel droplets are designed so that during each pulse of the laser beams LR1 and LR2, a plurality of droplets DP simultaneously pass through the first plurality of parallel bright stripes 537 to generate pancake-shaped droplets 27, and the pancake-shaped droplets 27 simultaneously pass through the second plurality of parallel bright stripes 527 to generate extreme ultraviolet radiation, while the droplets DP and the pancake-shaped droplets 27 are inside the stripes. In some embodiments, the effective width of the stripes is half of the distance 536, and the effective distance between the stripes is also half of the distance 536.

[0130] Figure 8An exemplary EUV lithography system for generating EUV radiation from a plurality of droplets DP according to some embodiments of the present disclosure is schematically shown. The EUV lithography system 800 includes an analyzer module 830 and a controller 840 coupled to each other. The analyzer module 830 receives an image of the droplet DP via a droplet detection module 820 consistent with one of the droplet detection modules 620A, 620B, 620C, or 620D, and determines, for example, calculates the timing of the laser generator 310 to generate subsequent pulses, which generate patterns 520 and 535 of light and dark stripes based on the positions of the plurality of droplets DP. The analyzer module 830 may command the laser generator 310 via the controller 840. In some embodiments, based on the timing of the laser generator 310, the analyzer module 830 commands the droplet generator 115 via the controller 840 to eject the droplet DP. In some embodiments, analyzer module 830 commands droplet illumination module 810 consistent with one of droplet illumination modules 610A, 610B, 610C, or 610D to illuminate excitation zone ZE with non-ionizing light to illuminate droplet DP.

[0131] Fig.9A as well as Fig. 9B Schematic diagram of a process for generating extreme ultraviolet radiation from a plurality of droplets according to some embodiments of the present disclosure. Fig.9A The process 900 can be achieved through Figure 1 as well as Figure 8 The EUV lithography system uses Fig. 6A , Figure 6B , Fig. 7A , Figure 7B In some embodiments, process 900 or a portion of process 900 is performed by the following Fig. 10A as well as Fig. 10B The computer system 1000 described herein is executed and / or controlled. The method includes an operation S910, in which the laser beam passing through the slit pair generates two or more stripes. Fig. 7A As shown, the ionizing laser beam 506 passes through the slit pair 522 and generates a pattern of light and dark stripes 520. In operation S920, two or more droplets DP are irradiated by two or more bright stripes 527 of the pattern of light and dark stripes 520 to generate extreme ultraviolet radiation. Fig. 7A As shown, the droplet DP passes through the bright stripe 527 and is irradiated by the ionizing laser beam 506, and generates extreme ultraviolet light rays 24 (extreme ultraviolet radiation). In operation S930, the extreme ultraviolet radiation generated by two or more droplets DP is collected and guided by a collecting mirror. Fig. 7A As shown, the extreme ultraviolet rays 24 are collected and directed by the collecting mirror 110 to Fig. 7A In operation S940, in a photolithography system (eg, Figure 2The collected and directed extreme ultraviolet radiation is used in a system of Figure 2 The reflective mask 205c) is imaged onto a substrate (eg, a target semiconductor substrate 210).

[0132] Fig. 9B The process 950 can be achieved by Figure 1 as well as Figure 8 The EUV lithography system uses Figure 6B as well as Figure 7B In some embodiments, process 950 or a portion of process 950 is performed by the following Fig. 10A as well as Fig. 10B The computer system 1000 described herein is executed and / or controlled. The method includes an operation S952, in which the free laser beam passing through the first slit pair generates two or more first stripes. Figure 7B As shown, the ionizing laser beam 506 passes through the slit pair 522 and generates two or more first bright stripes 527 of the pattern 520 of bright and dark stripes in the excitation region ZE. In operation 954, two or more second stripes are generated by the non-ionizing laser beam passing through the second slit pair. Figure 7B As shown, the non-ionizing laser beam 606 passes through the slit pair 530 and generates two or more second bright fringes 537 of the pattern 535 of bright and dark fringes in the excitation region ZE.

[0133] In operation S956, two or more droplets DP are irradiated by two or more second bright stripes 537 of the pattern 535 of bright and dark stripes to preheat the two or more droplets DP to generate two or more pancake-shaped droplets 27. In operation S958, two or more pancake-shaped droplets 27 are irradiated by two or more first bright stripes 527 of the pattern 520 of bright and dark stripes to generate extreme ultraviolet radiation. In operation S960, the extreme ultraviolet radiation generated by the two or more pancake-shaped droplets 27 is collected and guided by a collecting mirror. Fig. 7A As shown, the extreme ultraviolet rays 24 are collected by the collecting mirror 110 and directed to Figure 7B In operation S962, in a photolithography system (eg, Figure 2 The collected and directed extreme ultraviolet radiation is used in a system of Figure 2 The reflective mask 205c) is imaged onto a substrate (eg, a target semiconductor substrate 210).

[0134] Fig. 10A as well as Fig. 10B A computer system is shown of an apparatus for generating extreme ultraviolet radiation from a plurality of droplets according to some embodiments of the present disclosure. Fig. 10A1 is a schematic diagram of a computer system 1000 that performs a process for generating extreme ultraviolet radiation from a plurality of droplets according to one or more embodiments described above. All or part of the processes, methods, and / or operations of the aforementioned embodiments may be implemented using computer hardware and computer programs executed thereon. In some embodiments, the computer system 1000 provides Figure 8 The functions of the controller 840 and the analyzer module 830. Fig. 10A In the figure, the computer system 1000 is provided with a computer 1001, a keyboard 1002, a mouse 1003 and a monitor 1004. The computer 1001 includes an optical disk read only memory (for example, a compact disc read-only memory (CD-ROM) or a digital video disc read-only memory (DVD-ROM)) drive 1005 and a disk drive 1006.

[0135] Fig. 10B 1 is a diagram showing the internal configuration of the computer system 1000. Fig. 10B In addition to the CD-ROM drive 1005 and the disk drive 1006, the computer 1001 is also provided with one or more processors 1011, a read-only memory 1012, a random access memory (RAM) 1013, a hard disk 1014, and a bus 1015. The processor 1011 may be, for example, a microprocessor unit (MPU). The read-only memory 1012 stores programs such as boot up programs. The random access memory 1013 is connected to the processor 1011 and temporarily stores commands of the application program and provides a temporary storage area. The hard disk 1014 stores application programs, system programs, and data. The bus 1015 connects the processor 1011, the read-only memory 1012, etc. It should be noted that the computer 1001 may include a network card (not shown) for providing connection to a local area network (LAN).

[0136] In the aforementioned embodiment, the program for causing the computer system 1000 to execute the process for generating extreme ultraviolet radiation from a plurality of droplets may be stored in the optical disk 1021 or the magnetic disk 1022, inserted into the optical disk drive 1005 or the magnetic disk drive 1006, and transferred to the hard disk 1014. Alternatively, the program may also be transferred to the computer 1001 via a network (not shown) and stored in the hard disk 1014. When executed, the program is loaded into the random access memory 1013. The program may be loaded from the optical disk 1021 or the magnetic disk 1022 or directly from the network. The program does not necessarily include, for example, an operating system (OS) or a third-party program to cause the computer 1001 to execute the process for manufacturing a photolithography mask for a semiconductor device in the aforementioned embodiment. The program may include only a command portion to call out the appropriate function (module) in the control mode and obtain the desired result.

[0137] According to some embodiments of the present disclosure, a method for generating extreme ultraviolet radiation includes simultaneously irradiating two or more target droplets with a first laser beam in an extreme ultraviolet radiation source device to generate extreme ultraviolet radiation. The method also includes collecting and directing the extreme ultraviolet radiation generated from the two or more target droplets through an imaging mirror. In some embodiments, the method also includes configuring a droplet generator to release two or more target droplets in a first parallel line in a first plane. In some embodiments, the method also includes dividing the first laser beam into two parts, interfering the two parts of the first laser beam to generate two or more stripes, and irradiating each of the two or more target droplets with one of the two or more stripes. In some embodiments, the method also includes configuring the two parts of the first laser beam to pass through a slit pair to generate two or more stripes. In some embodiments, the method also includes generating two or more stripes in the first plane. The two or more stripes are parallel to the first parallel line, and each of the two or more target droplets is configured to simultaneously pass through a separate stripe of the two or more stripes. In some embodiments, the first plane is perpendicular to the direction of the first laser beam, and the method also includes using the collected and directed extreme ultraviolet radiation in a lithography system to image a photomask on a substrate. In some embodiments, the method further includes dividing the first laser beam into three or more parts, interfering the three or more parts of the first laser beam to generate two or more stripes, and irradiating each of the two or more target droplets with one of the two or more stripes. In some embodiments, the method further includes generating a plasma plume by irradiating the two or more target droplets with the two or more stripes of the first laser beam. The extreme ultraviolet radiation is generated by the plasma plume. In some embodiments, the method further includes configuring the two parts of the first laser beam to pass through different path lengths, and offsetting the positions of the two or more stripes through the different path lengths. In some embodiments, the method further includes preheating the two or more target droplets simultaneously with a second laser beam in the extreme ultraviolet radiation source, and generating flat pancake-shaped droplets by preheating. The preheating is before irradiating the two or more target droplets with the first laser beam.

[0138] According to some embodiments of the present disclosure, a method for generating extreme ultraviolet radiation includes generating two or more stripes by a first laser beam passing through a first slit pair. The method includes irradiating two or more target droplets through the two or more stripes to generate extreme ultraviolet radiation. Each of the two or more target droplets simultaneously passes through one of the two or more stripes. The method also includes collecting and directing the extreme ultraviolet radiation generated from the two or more target droplets through an imaging mirror. In some embodiments, the method also includes dividing the first laser beam into two parts and interfering the two parts of the first laser beam to generate two or more stripes. In some embodiments, the method also includes generating a plasma plume by irradiating two or more target droplets with the two or more stripes of the first laser beam. The extreme ultraviolet radiation is generated by the plasma plume. In some embodiments, the method also includes configuring the droplet generator to release two or more target droplets simultaneously.

[0139] According to some embodiments of the present disclosure, an extreme ultraviolet radiation source includes a first laser source configured to generate a first laser beam and a collecting mirror having two or more slits. The radiation source includes a droplet generator configured to simultaneously release two or more target droplets in a first parallel line in a first plane. The radiation source also includes an optical system configured to divide the first laser beam into two or more parts and pass two or more parts of the first laser beam through two or more slits to generate two or more first stripes parallel to the paths of the two or more target droplets. The radiation source includes a controller that couples and controls the first laser source and the droplet generator. The controller is configured to emit laser pulses of the first laser source to irradiate the two or more target droplets released simultaneously through two or more first stripes. Each first stripe irradiates a droplet. In some embodiments, the optical system of the extreme ultraviolet radiation source includes a lens configured to generate a collimated beam of the first laser beam. The collimated beam is configured to be incident on two or more slits. In some embodiments, the slit has a rectangular shape. In some embodiments, the extreme ultraviolet radiation source further comprises a second laser source, which is configured to generate a second preheating laser beam. The optical system is further configured to divide the second preheating laser beam into two or more parts, and pass the two or more parts of the second preheating laser beam through two or more slits to generate two or more second stripes parallel to the path of the two or more target droplets. In some embodiments, the optical system is configured to generate a first number of first stripes equal to a second number of second stripes, and the first number of first stripes and the second number of second stripes are between 2 and 8, generate two or more first stripes in the excitation region, and generate two or more second stripes in the path of the two or more target droplets from the droplet generator to the excitation region and before the excitation region. In some embodiments, the extreme ultraviolet radiation source further comprises a droplet illumination module and a droplet detection module, and the droplet illumination module is configured to illuminate the excitation region with non-ionized light to illuminate the two or more target droplets. The droplet detection module is configured to capture an image from the excitation region to determine the speed of the two or more target droplets, and determine the timing of turning on and off the first and second laser sources based on the speed.

[0140] In some embodiments, the above processes and methods are implemented to increase the efficiency of generating EUV radiation by irradiating multiple droplets simultaneously.

[0141] The features of several embodiments are summarized above so that those skilled in the art can better understand various aspects of the present disclosure. It should be understood by those skilled in the art that the present disclosure can be easily used as a basis for designing or modifying other processes and structures to achieve the same purposes and / or achieve the same advantages of the embodiments introduced herein. It should also be understood by those skilled in the art that such equivalent configurations do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions and modifications may be made to the present disclosure without departing from the spirit and scope of the present disclosure.

Claims

1. A method for generating extreme ultraviolet radiation, comprising: configuring a droplet generator to simultaneously release two or more target droplets in a plurality of first parallel lines in a first plane; In an extreme ultraviolet radiation source device, simultaneously irradiating two or more target droplets with a first laser beam to generate extreme ultraviolet radiation, wherein simultaneously irradiating the two or more target droplets with the first laser beam comprises: dividing the first laser beam into two parts; interfering the two portions of the first laser beam to generate two or more bright fringes; and simultaneously illuminating each of the two or more target droplets with one of the two or more bright fringes; and The EUV radiation generated from the two or more target droplets is collected and directed by an imaging mirror.

2. The method for generating extreme ultraviolet radiation according to claim 1, wherein the first plane is perpendicular to a direction of the first laser beam, the method further comprising: The collected and directed EUV radiation is used in a photolithography system to image a photomask onto a substrate.

3. The method of generating extreme ultraviolet radiation according to claim 1, further comprising: The two portions of the first laser beam are configured to pass through a pair of slits to generate the two or more bright fringes.

4. The method of generating extreme ultraviolet radiation according to claim 1, further comprising: Generating the two or more bright stripes in the first plane, wherein the two or more bright stripes are parallel to the plurality of first parallel lines; as well as Each of the two or more target droplets is configured to simultaneously pass through a separate bright stripe of the two or more bright stripes.

5. The method of generating extreme ultraviolet radiation according to claim 1, further comprising: dividing the first laser beam into three or more portions; interfering the three or more portions of the first laser beam to generate the two or more bright fringes; as well as Each of the two or more target droplets is illuminated with one of the two or more bright fringes.

6. The method of generating extreme ultraviolet radiation as claimed in claim 1, further comprising: A plasma plume is generated by irradiating the two or more target droplets with the two or more bright stripes of the first laser beam, wherein the extreme ultraviolet radiation is generated by the plasma plume.

7. The method of generating extreme ultraviolet radiation as claimed in claim 1, further comprising: configuring the two portions of the first laser beam to traverse different path lengths; as well as The positions of the two or more bright fringes are offset due to the different path lengths.

8. The method of generating extreme ultraviolet radiation of claim 1, further comprising: Preheating the two or more target droplets simultaneously with a second laser beam in the EUV radiation source, wherein the preheating is prior to irradiating the two or more target droplets with a first laser beam; and This preheating produces flat, pancake-shaped droplets.

9. A method of generating extreme ultraviolet radiation, comprising: Producing two or more bright fringes by a first laser beam passing through a first pair of slits; irradiating two or more target droplets through the two or more bright stripes to produce extreme ultraviolet radiation, wherein each of the two or more target droplets simultaneously passes through one of the two or more bright stripes; as well as The EUV radiation generated from the two or more target droplets is collected and directed by an imaging mirror.

10. The method of generating extreme ultraviolet radiation of claim 9, further comprising: dividing the first laser beam into two parts; as well as The two portions of the first laser beam are interfered to generate the two or more bright fringes.

11. The method of generating extreme ultraviolet radiation of claim 9, further comprising: A plasma plume is generated by irradiating the two or more target droplets with the two or more bright stripes of the first laser beam, wherein extreme ultraviolet radiation is generated by the plasma plume.

12. The method of generating extreme ultraviolet radiation of claim 9, further comprising: A droplet generator is configured to release the two or more target droplets simultaneously.

13. An extreme ultraviolet radiation source, comprising: a first laser source configured to generate a first laser beam; a collecting mirror comprising two or more slits; a droplet generator configured to release two or more target droplets simultaneously on a plurality of first parallel lines in a first plane; an optical system configured to split the first laser beam into two or more parts and pass the two or more parts of the first laser beam through the two or more slits to generate two or more first bright streaks parallel to a path of the two or more target droplets; as well as A controller is coupled to and controls the first laser source and the droplet generator, wherein the controller is configured to emit a laser pulse of the first laser source to illuminate two or more target droplets released simultaneously through the two or more first bright stripes, wherein each first bright stripe illuminates one droplet.

14. The EUV radiation source of claim 13, wherein the optical system comprises a lens configured to produce a collimated beam of the first laser beam, and wherein the collimated beam is configured to be incident on the two or more slits.

15. The EUV radiation source of claim 13, wherein a plurality of the slits have a rectangular shape.

16. The extreme ultraviolet radiation source of claim 13, further comprising: a second laser source configured to generate a second preheating laser beam, wherein the optical system is further configured to split the second preheating laser beam into two or more parts and pass the two or more parts of the second preheating laser beam through the two or more slits to generate two or more second bright stripes parallel to a path of the two or more target droplets.

17. The EUV radiation source of claim 16, wherein the optical system is configured to: Generate a first number of the first bright stripes, the first number of the first bright stripes is equal to a second number of the second bright stripes, and the first number of the first bright stripes and the second number of the second bright stripes are between 2 and 8; generating the two or more first bright stripes in an excitation region, and The two or more second bright streaks are generated in a path of the two or more target droplets from the droplet generator to the excitation region and before the excitation region.

18. The extreme ultraviolet radiation source of claim 17, further comprising: a droplet illumination module configured to illuminate the excitation region with non-ionizing light to illuminate the two or more target droplets; as well as A droplet detection module is configured to capture images from the excitation area to determine a velocity of the two or more target droplets, and determine a time to turn on and off the first laser source and the second laser source based on the velocity.

19. An extreme ultraviolet radiation source, comprising: a laser source configured to generate a laser beam; a beam splitter configured to split the laser beam into two laser beams; a collecting mirror comprising two openings, through which the two laser beams pass respectively; as well as a droplet generator, comprising a plurality of nozzles, configured to release a plurality of droplets simultaneously and in parallel, The extreme ultraviolet radiation source is configured so that the two laser beams generate a plurality of parallel bright stripes in an excitation region and each of the plurality of droplets is simultaneously irradiated by each of the plurality of bright stripes.

20. The EUV radiation source of claim 19, wherein the laser beam is a pre-pulse laser.

21. The EUV radiation source of claim 19, wherein the laser beam is a main pulse laser.

22. The extreme ultraviolet radiation source of claim 19, wherein the two openings are two slits, and a distance between the centers of the two slits is in the range of 0.5 mm to 10 mm.

23. The EUV radiation source of claim 22, wherein a width of each of the two slits is in the range of 200 nm to 10 μm.

24. The EUV radiation source of claim 19, wherein the EUV radiation source is configured such that the two laser beams are in phase when passing through the two openings.

25. The EUV radiation source of claim 19, wherein the number of droplets is in the range of 2 to 8.

26. An extreme ultraviolet radiation source comprising: a laser source configured to generate a pre-pulse laser beam and a main pulse laser beam; a collecting mirror including a first slit pair; as well as a droplet generator, comprising a plurality of nozzles, configured to release a plurality of droplets simultaneously and in parallel, The extreme ultraviolet radiation source is configured so that at least one of the pre-pulse laser beam or the main pulse laser beam passes through the first slit pair to generate a plurality of bright stripes in an excitation region by interference, and each of the plurality of droplets is simultaneously irradiated by each of the plurality of bright stripes.

27. The extreme ultraviolet radiation source of claim 26, further comprising a plurality of droplet illumination modules to illuminate the plurality of droplets respectively.

28. The extreme ultraviolet radiation source of claim 27, further comprising a plurality of droplet detection modules to respectively acquire reflection images of the plurality of droplets.

29. The extreme ultraviolet radiation source of claim 28, further comprising a controller configured to control the laser source and the droplet generator based on a detection result of the plurality of droplet detection modules.

30. The EUV radiation source of claim 26, wherein a distance between centers of the first pair of slits is in the range of 200 nm to 10 μm.

31. The EUV radiation source of claim 26, further comprising a second pair of slits.

32. The EUV radiation source of claim 31, wherein the EUV radiation source is configured such that the pre-pulse laser beam passes through the first pair of slits and the main pulse laser beam passes through the second pair of slits.

33. The extreme ultraviolet radiation source of claim 32, wherein: A wavelength of the pre-pulse laser beam is different from a wavelength of the main pulse laser beam, and A slit width of the first slit pair is different from a slit width of the second slit pair.

34. A pattern forming method comprising: generating one or more laser beams; The one or more laser beams are caused to generate a plurality of bright stripes in an excitation region through interference; Simultaneous generation of multiple target droplets; Generating an extreme ultraviolet light by simultaneously irradiating each of the plurality of target droplets with each of the plurality of bright stripes generated by the one or more laser beams; collecting the extreme ultraviolet light through a collecting mirror; directing the extreme ultraviolet light to a photomask; as well as A photoresist layer is exposed using the extreme ultraviolet light reflected by the photomask.

35. The pattern forming method of claim 34, wherein a laser beam passes through a pair of slits provided in the collecting mirror to cause the interference.

36. The pattern forming method of claim 34, wherein two laser beams pass through two openings provided in the collecting mirror to cause interference.

37. The pattern forming method of claim 34, wherein: The one or more laser beams include a pre-pulse laser beam and a main pulse laser beam, and The pre-pulse laser beam and the main pulse laser beam respectively generate the plurality of bright stripes.

38. The pattern forming method of claim 37, wherein in a direction in which the plurality of target droplets travel, a position of the plurality of bright stripes generated by the pre-pulse laser beam is different from a position of the plurality of bright stripes generated by the main pulse laser beam.

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