Method and device for tuning flow rate profile

Abstract

The radiation source includes a mass transfer system, an illumination source, and a jet flow generator. The mass transfer system directs the target material toward the target area. The illumination source irradiates the target material at the target area to generate radiation as the output of the radiation source. The jet flow generator directs a jet of gas toward the target area. The jet flow generator includes a flow injector and a diffuser. The flow injector controls the velocity profile of the jet flow. The diffuser controls the diffusion of the jet flow.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] This application claims priority to U.S. Application No. 63 / 621,936, filed January 17, 2024, titled “Method and device for tuning a flow rate profile,” the contents of which are incorporated herein by reference in their entirety.

[0003] Technology field

[0004] The present application relates to an extreme ultraviolet (EUV) radiation source and a method thereof. EUV radiation can be used as exposure radiation, for example, in a lithography process for manufacturing semiconductor devices. Background Technology

[0005] A lithography device is a device that applies a desired pattern onto a substrate, typically onto a target portion of the substrate. A lithography device can be used, for example, in the manufacture of an integrated circuit (IC). In such cases, a patterning device, which may be a mask or a reticle, can be used to generate a circuit pattern to be formed on individual layers of the IC. This pattern can be transferred onto a target portion (e.g., part of a die, one die, or several dies) on a substrate (e.g., a silicon wafer). The transfer of the pattern is typically achieved through imaging onto a layer of radiation-sensitive material (photoresist or simply "resist") provided on the substrate. Generally, a single substrate will comprise a network of adjacent target portions that are continuously patterned. A conventional lithography device includes a so-called stepper, which irradiates each target portion by exposing the entire pattern onto the target portion at once, and a so-called scanner, which irradiates each target portion by scanning the pattern through a radiation beam in a given direction ("scanning" direction) while simultaneously scanning the target portions parallel or antiparallel to this scanning direction. It is also possible to transfer a pattern from a patterning device to a substrate by imprinting the pattern onto the substrate.

[0006] Generally, a lithography device includes an illumination system that conditions the radiation generated by a radiation source before it is incident on a patterning device. A patterned beam of EUV light can be used to create very fine features on a substrate. EUV light (often also called soft X-rays) is generally defined as electromagnetic radiation with wavelengths ranging from about 5 to 100 nm. The wavelength of particular interest for photolithography occurs at 13.5 nm.

[0007] A method for generating EUV light involves, but is not limited to, converting a source material having a chemical element having one or more emission lines within the EUV range into a plasma state. Such elements may include, but are not necessarily limited to, xenon, lithium, tin, etc.

[0008] In one such method, often called laser-generated plasma ("LPP"), a desired plasma can be generated by irradiating a source material, for example in the form of a droplet, stream, or wire. In another method, also called discharge-generated plasma ("DPP"), a plasma can be generated by placing a source material with a suitable emission line between a pair of electrodes and causing an electric discharge to occur between the electrodes.

[0009] Buffer gas may be used in an EUV source to mitigate the deposition of contaminants on the surface of the EUV source. When a buffer gas with appropriate flow velocity and directionality is generated, the viscosity of the buffer gas may be utilized to guide the consumed plasma material toward an appropriate outlet (e.g., an exhaust port). Controlling the flow of the buffer gas can significantly reduce the rate of contaminant deposition on the chamber surface. The flow of the buffer gas may be influenced by one or more optical elements placed in the gas flow path within the EUV source. A given design for the gas flow system can be made to fit the given architecture of the optical elements, but problems may arise when the architecture of the optical elements is updated or undergoes redesign. In such situations, the existing design of the gas flow system may become unsuitable, which can increase costs and complexity by triggering a redesign of the gas flow system.

[0010] Therefore, it is desirable to improve the gas flow system so that performance objectives can be achieved without being affected by structural changes around the gas flow system.

[0011] In some embodiments, the radiation source includes a mass transfer system, an illumination source, and a jet flow generator. The mass transfer system is configured to direct the target material toward the target area. The illumination source is configured to irradiate the target material toward the target area to generate radiation as the output of the radiation source. The jet flow generator is configured to direct a jet flow of gas toward the target area. The jet flow generator includes a flow injector and a diffuser. The flow injector is configured to regulate the velocity profile of the jet flow. The diffuser is configured to regulate the diffusion of the jet flow.

[0012] In some embodiments, the jet flow generator includes a flow injector and a diffuser. The flow injector is configured to control the velocity profile of the gas jet flow. The diffuser is configured to control the diffusion of the jet flow. The jet flow generator is configured to direct the jet flow having the velocity profile toward a target area.

[0013] In some embodiments, the method comprises controlling the velocity profile of a gas jet flow using a flow injector comprising a cavity to create a pressure gradient for the gas flow within the flow injector. The method also comprises controlling the diffusion of the jet flow using a diffuser comprising a spray hole to create a diffused gas flow to be coupled with the jet flow at the output structure of the flow injector.

[0014] Further features of various embodiments of the present invention are described in more detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. Such embodiments are presented herein merely for illustrative purposes. Additional embodiments will be apparent to a person skilled in the art based on the teachings contained herein. Brief explanation of the drawing

[0015] The accompanying drawings, which are incorporated herein and form part of the specification, are intended to illustrate the invention and, together with the detailed description, further explain the principles of the invention and enable a person skilled in the art to practice the embodiments described herein. FIG. 1 shows a reflective lithography apparatus according to some embodiments. Figure 2 shows a lithography cell according to some embodiment. FIGS. 3a, FIGS. 3b, and FIGS. 4 show more details of a radiation source that can be used in a reflective lithography device according to some embodiments. Figure 5 shows a part of a radiation source according to some embodiments. Figure 6 shows a part of a radiation source according to some embodiments. FIG. 7 shows a jet flow generator according to some embodiments. Figure 8 shows a graph of the velocity profile of the jet flow for various settings of the jet flow generator according to some embodiments. Figure 9 shows an intensity map of the velocity profile of the jet flow according to some embodiments. FIG. 10 shows a radiation system according to some embodiments. Figure 11 shows a flowchart of a method for controlling the velocity profile of a jet flow according to some embodiments. The features of the present disclosure will become more apparent from the detailed description provided below when taken together with the drawings, in which similar reference numerals identify corresponding elements throughout. In the drawings, similar reference numerals generally represent elements that are identical, functionally similar, and / or structurally similar. Also, generally, the leftmost number(s) of a reference numeral identify the drawing in which the reference numeral first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as drawings in scale. Specific details for implementing the invention

[0016] The embodiments described herein, and references to "one embodiment," "embodiment," "exemplary embodiment," "an example embodiment," etc. in this specification, indicate that the described embodiments may include specific features, structures, or characteristics, but not all embodiments are required to include specific features, structures, or characteristics. Furthermore, such phrases do not necessarily refer to the same embodiment. Additionally, it will be understood that when specific features, structures, or characteristics are described in relation to an embodiment, it is within the knowledge of those skilled in the art to implement such features, structures, or characteristics in relation to another embodiment, regardless of whether they are explicitly described.

[0017] Spatially relative terms such as "below," "below," "lower," "above," "on top," and "upper" may be used herein for ease of explanation to describe the relationship between one element or feature and another element(s) or feature(s) illustrated in the drawings. Spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. The device may be oriented differently (rotated 90 degrees or oriented in a different way), and the spatially relative descriptive terms used herein may be interpreted accordingly.

[0018] Terms such as “about,” “approximately,” etc. may be used in this specification to indicate a given amount of value that may vary based on a specific technique. Depending on the specific technique, terms such as “about,” “approximately,” etc. may indicate a given amount of value that varies, for example, within 10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

[0019] Aspects of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. Aspects of the present disclosure may also be implemented as instructions stored on a computer-readable medium that can be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM); random access memory (RAM); magnetic disk storage medium; optical storage medium; flash memory device; electrical, optical, acoustic, or other forms of radio signals (e.g., carrier waves, infrared signals, digital signals, etc.). Additionally, firmware, software, routines, and / or instructions may be described in this specification as performing specific operations. However, it should be recognized that such descriptions are for convenience only, and that such operations originate from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc. The term “machine-readable medium” may be interchangeable with, for example, “computer program product,” “computer-readable medium,” “non-transient computer-readable medium,” or similar terms. In this specification, the term “non-transient” may be used to characterize one or more forms of a computer-readable medium excluding transient radio signals.

[0020] However, before describing these aspects in detail, it would be beneficial to present an exemplary environment in which the aspects of the present disclosure may be implemented.

[0021] Exemplary lithography system

[0022] FIG. 1 shows a lithography apparatus (100) in which an embodiment of the present disclosure can be implemented. In some embodiments, the lithography apparatus (100) comprises an illumination system (illuminator) (IL) configured to condition a radiation beam (B) (e.g., deep ultraviolet or extreme ultraviolet radiation), a support structure (e.g., mask table) (MT) configured to support a patterning device (e.g., mask, reticle, or dynamic patterning device) (MA) and connected to a first positioner (PM) configured to accurately position the patterning device (MA), and a substrate table (e.g., wafer table) (WT) configured to hold a substrate (e.g., resist-coated wafer) (W) and connected to a second positioner (PW) configured to accurately position the substrate (W). The lithography device (100) also includes a projection system (PS) configured to project a pattern applied by a radiation beam (B) by a patterning device (MA) onto a target portion (C) (e.g., comprising one or more dies) of a substrate (W). In the lithography device (100), the patterning device (MA) and the projection system (PS) are reflective.

[0023] The illumination system (IL) may include various types of optical components, such as refractive, reflective, reflector-refractive, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, to direct, shape, or control the radiation beam (B). The illumination system (IL) may also include a sensor (ES) that provides measurements for one or more of, for example, energy per pulse, photon energy, intensity, average power, etc. The illumination system (IL) may include a measurement sensor (MS) for measuring the movement of the radiation beam (B) and a uniformity compensator (UC) capable of controlling the uniformity of the illumination slit. The measurement sensor (MS) may be placed at other locations. For example, the measurement sensor (MS) may be on or near the substrate table (WT).

[0024] In some embodiments, the support structure (MT) may support the patterning device (MA) in a manner that depends on the orientation of the patterning device (MA) relative to a reference frame, the design of the lithography device (100), and other conditions, such as whether the patterning device (MA) is maintained in a vacuum environment. The support structure (MT) may implement mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device (MA). The support structure (MT) may be a frame or a table. The support structure (MT) may be fixed or movable. Using a sensor, the support structure (MT) may ensure that the patterning device (MA) is in a desired position (e.g., a position given to the projection system (PS)).

[0025] The term “patterning device” may be used herein to refer to any device that can be used to impart a pattern to a cross-section of a radiation beam (B) to create a pattern on a target portion (C) of a substrate (W), for example. The pattern imparted to the radiation beam (B) may correspond to a specific functional layer of the device created on the target portion (C) to form an integrated circuit.

[0026] The patterning device (MA) may be reflective. Examples of the patterning device (MA) include a reticle, a mask, a programmable mirror array, or a programmable LCD panel. The mask may include different mask types, such as binary, alternating phase shift, or attenuated phase shift mask types, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix array of small mirrors, each of which can be individually tilted to reflect an incident radiation beam in various directions. The tilted mirrors can impart a pattern to the radiation beam (B) reflected by the matrix of small mirrors.

[0027] In some embodiments, the term "projection system" (PS) may be used herein to refer to any type of projection system including refractive, reflective, semi-refractive, magnetic, electromagnetic, and electrostatic optical systems or any combination thereof, which is suitable for the exposure radiation used or for other factors such as the use of immersion fluid on the substrate (W) or the use of a vacuum. Atmospheric gases may absorb EUV or electrons used to expose the substrate. Therefore, a vacuum environment may be used for EUV or electron beam radiation. A vacuum environment may be provided throughout the entire beam path using vacuum walls and vacuum pumps.

[0028] The lithography apparatus (100) may be of the type having two (dual-stage) or more substrate tables (WT) (and / or two or more mask tables). In such a “multi-stage” apparatus, additional substrate tables (WT) may be used in parallel, or preparation steps may be performed on one or more tables while using one or more other substrate tables (WT) for exposure. In some situations, the additional tables may be different from the substrate tables (WT).

[0029] In some embodiments, the lithography device (100) may be of a type in which at least a portion of the substrate can be covered with a liquid having a relatively high refractive index, such as water, to fill the space between the projection system and the substrate. The immersion liquid may also be applied to other spaces of the lithography device, for example, between the mask and the projection system. The immersion technique may increase the numerical aperture of the projection system. As used herein, the term “immersion” does not mean that a structure such as a substrate must be submerged in liquid. For example, liquid may be positioned between the projection system and the substrate during exposure.

[0030] An illuminator (IL) can receive a radiation beam from a radiation source (SO). The source (SO) and the lithography device (100) may be separate physical entities. In such a case, the source (SO) is not considered to be part of the lithography device (100), and the radiation beam (B) may be transmitted from the radiation source (SO) to the illuminator (IL) with the help of a beam transmission system (not shown) which may include, for example, a suitable directional mirror and / or a beam expander. In another embodiment, the source (SO) may be an integrated part of the lithography device (100). The radiation system may include a source (SO), an illuminator (IL), and / or a beam transmission system (BD).

[0031] In some embodiments, an illuminator (IL) may be used to condition the radiation beam (B) so that there is a desired uniformity and intensity distribution across the cross section of the radiation beam (B). The desired uniformity of the radiation beam (B) may be maintained by using a uniformity compensator (UC). The uniformity compensator (UC) may include a plurality of protrusions (e.g., fingers) that can be adjusted in the path of the radiation beam (B) to control the uniformity of the radiation beam (B). A measurement sensor (MS) may be used to monitor the uniformity of the radiation beam (B).

[0032] A radiation beam (B) can be incident on a patterning device (MA) held on a support structure (MT), and in this way, the radiation beam (B) can be patterned by the patterning device (MA). In a lithography device (100), the radiation beam (B) can be reflected from the patterning device (e.g., mask) (MA). After being reflected from the patterning device (MA), the radiation beam (B) can pass through a projection system (PS), and the projection system (PS) focuses the radiation beam (B) onto a target portion (C) of a substrate (W). Using a second positioner (PW) and a position sensor (IF2) (e.g., an interferometer device, a linear encoder, or a capacitive sensor), the substrate table (WT) can be moved accurately (e.g., to position various target portions (C) within the path of the radiation beam (B). Likewise, a first positioner (PM) and another position sensor (IF1) may be used to accurately position a patterning device (e.g., a mask) (MA) in the path of a radiation beam (B). The patterning device (MA) and the substrate (W) may be aligned using mask alignment marks (M1, M2) and substrate alignment marks (P1, P2).

[0033] In some embodiments, the lithography device (100) may be used in at least one of the following modes:

[0034] 1. In step mode, while the entire pattern applied to the radiation beam (B) is projected onto the target portion (C) at once, the support structure (MT) and the substrate table (WT) may be kept in a substantially stationary state (e.g., single static exposure). Then, the substrate table (WT) may be shifted in the X and / or Y directions so that a different target portion (C) can be exposed.

[0035] 2. In scan mode, while a pattern applied to the radiation beam is projected onto the target portion (C), the support structure (MT) and the substrate table (WT) can be scanned synchronously (e.g., single dynamic exposure). The speed and orientation of the substrate table (WT) relative to the support structure (MT) can be determined by the magnification (reduction ratio) and image inversion characteristics of the projection system (PS).

[0036] 3. In another mode, the support structure (MT) may be maintained in a substantially stationary state while holding the programmable patterning device, and the substrate table (WT) may be moved or scanned while the pattern imparted by the radiation beam is projected onto the target portion (C). A pulsed radiation source (SO) may be employed, and the programmable patterning device is updated between successive radiation pulses after each movement of the substrate table (WT) or during a scan. This mode of operation can be easily applied to maskless lithography using a programmable patterning device such as a programmable mirror array.

[0037] Combinations and / or variations of the usage modes described above, or completely different usage modes, may also be employed.

[0038] In some embodiments, the lithography device (100) may include an EUV radiation source configured to generate an EUV radiation beam for extreme ultraviolet (EUV) lithography. The EUV source is configured within a radiation system, and the corresponding illumination system may be configured to condition the EUV radiation beam of the EUV source.

[0039] Exemplary lithography cell

[0040] FIG. 2 illustrates a lithography cell (200), often referred to as a lithocell or cluster according to some embodiments. A lithography device (100) (see FIG. 1, 3a, 3b and 4) may form part of the lithography cell (200). The lithography cell (200) may also include one or more devices for performing pre-exposure and post-exposure processes on a substrate. Such devices include a spin coater (SC) for depositing a resist layer, a developer (DE) for developing the exposed resist, a cooling plate (CH), and a bake plate (BK). A substrate handler or robot (RO) picks up a substrate from an input / output port (I / O1, I / O2), moves it between different process devices, and delivers it to a loading bay (LB) of the lithography device (100). These devices, also collectively referred to as tracks, are under the control of a Track Control Unit (TCU) controlled by a Supervisory Control System (SCS), and the Supervisory Control System also controls the lithography device through a Lithography Control Unit (LACU). In this way, various devices can be operated to maximize throughput and processing efficiency.

[0041] Exemplary lighting sources and lighting optics

[0042] FIG. 3a shows different drawings of a source (SO) (e.g., source collector device), an illumination system (IL), and a projection system (PS) that can be used in a lithography device (100) according to some embodiments. The source (SO) is configured and arranged so that a vacuum environment can be maintained within the enclosure structure (320) of the source (SO). An EUV radiation-emitting plasma (310) can be formed by a discharge-generating plasma source. In some embodiments, a plasma of excited tin (Sn) (e.g., excited via a laser) is used to generate EUV radiation.

[0043] Radiation emitted by an EUV radiation-emitting plasma (310) can be transferred from a source chamber (311) into a collector chamber (312) through an optional gas barrier or contaminant trap (330) (sometimes referred to as a contaminant barrier or foil trap) located inside or behind the opening of the source chamber (311). The contaminant trap (330) may include a channel structure. The contaminant trap (330) may also include a gas barrier and / or a channel structure.

[0044] In some embodiments, the collector chamber (312) may include a radiation collector (CO). The radiation collector (CO) may be a so-called grazing incident collector. The radiation collector (CO) may include an upstream radiation collector side (351) and a downstream radiation collector side (352). Radiation passing across the radiation collector (CO) may be reflected from a grating spectrum filter (340) and focused at a virtual source point (INTF). The virtual source point (INTF) may also be referred to as an intermediate focus. The source collector device may be arranged so that the intermediate focus (INTF) is located at or near the opening (319) of the enclosure structure (320). The virtual source point (INTF) may be an image of the EUV radiation-emitting plasma (310). The grating spectrum filter (340) may be used to suppress infrared (IR) radiation.

[0045] The radiation then passes through an illumination system (IL). The illumination system (IL) may include a faceted field mirror device (322) and a faceted pupil mirror device (324) arranged to provide the required angular distribution of the radiation beam (321) in the patterning device (MA) as well as the required uniformity of radiation intensity in the patterning device (MA). When the radiation beam (321) is reflected from the patterning device (MA) held by a support structure (MT), a patterned beam (326) is formed, and the patterned beam (326) is imaged onto a substrate (W) held by a wafer stage or substrate table (WT) by a projection system (PS) through reflective elements (328, 329). In some embodiments, other configurations of mirrors and / or optical devices may be used to direct the radiation beam (321) toward the patterning device (MA).

[0046] Generally, there may be more elements in the lighting system (IL) and projection system (PS) than are shown. A grating spectrum filter (340) may be optionally present depending on the type of lithography device. Additionally, there may be more mirrors than are shown in FIG. 2a, and, for example, there may be 1 to 6 additional reflective elements within the projection system (PS) than are shown in FIG. 2a.

[0047] In some embodiments, the uniformity compensator (UC), sensor (ES), and / or measurement sensor (MS) shown in FIGS. 2a and 2b may be the same as described above with reference to FIG. 1.

[0048] As illustrated in FIG. 2a, the collector (CO) is shown as an example of a nested collector (or collector mirror) having grazing incident reflectors (353, 354, 355). The grazing incident reflectors (353, 354, 355) may be arranged axially symmetrically around the optical axis (O). This type of collector optical device may be used in combination with a discharge generating plasma source, often referred to as a DPP source.

[0049] FIG. 3b shows another drawing of a source (SO) having an alternative collector optical device that can be used in a lithography device (100) according to some embodiments. It should be understood that any structures shown in FIG. 3a that are not shown in FIG. 3b (for the sake of clarity of the drawings) may be included in the embodiments referenced in FIG. 3b. In FIG. 3b, elements having the same reference numerals as in FIG. 3a have the same or substantially similar structure and function as those described with reference to FIG. 3a.

[0050] In some embodiments, the lithography device (100) may be used to expose a substrate (W), such as a resist-coated wafer, to a patterned beam of EUV illumination. In FIG. 3b, the illumination system (IL) and the projection system (PS) are combined to form an exposure device (356) that uses EUV light from a source (SO) (e.g., an integrated circuit lithography tool such as a stepper, scanner, step and scan system, direct lighting system, or a device using a contact and / or proximity mask). The lithography device (100) may include a collector (358) that reflects EUV light from an EUV radiation-emitting plasma (310) along a path to the exposure device (356) to irradiate the substrate (W). The collector (358) may include a near-perpendicular incident collector mirror having a reflective surface in the shape of a prolate spheroid (e.g., an ellipse rotated about a major axis). The prolate spheroid structure may have a graded multilayer coating in which molybdenum and silicon layers are alternately stacked, and may include, in some cases, one or more high-temperature diffusion barrier layers, planarization layers, capping layers and / or etching stop layers.

[0051] FIG. 4 shows a detailed drawing of a source (SO) and associated elements that may be used in a lithography apparatus (100) according to some embodiments. In FIG. 4, elements having the same reference numerals as those in FIG. 1, 3a, and 3b have the same or substantially similar structure and function as described with reference to FIG. 1, 3a, and 3b. In some embodiments, the source (SO) may be an LPP EUV source. The source (SO) may include a laser system (402) (or a suitable lighting system) for generating illumination used to generate an EUV generating plasma. The source (SO) may generate a series of light pulses and transmit the light pulses to a light source chamber (312). In the case of the lithography apparatus (100), the light pulses may travel along one or more beam paths from the laser system (402) into the chamber (312) to illuminate the source material (or target material) in the irradiation area (404) (or target area, or primary focus) to generate plasma. For example, an EUV radiation-emitting plasma (310) (Fig. 3b) is generated in an irradiation area (404). EUV light is generated by the plasma. The EUV light is used for substrate exposure in an exposure device (356).

[0052] In some embodiments, the laser system (402) may include a pulsed laser device, for example, a pulsed gas discharge CO2 laser device that generates radiation at, for example, 9.3 pm or 10.6 pm, using DC or RF excitation and operating at a relatively high power (e.g., 10 kW or more) and a high pulse repetition rate (e.g., 50 kHz or more). In some embodiments, the laser may be an axial flow RF-pumped CO2 laser having an oscillator-amplifier configuration (e.g., a master oscillator / power amplifier (MOPA) or a power oscillator / power amplifier (POPA)), which includes a multi-stage amplification and has a seed pulse initiated by a Q-switched oscillator having relatively low energy and a high repetition rate (e.g., capable of operating at 100 kHz). Then, the laser pulse from the oscillator may be amplified, shaped, and / or focused before reaching the irradiation area (404). A continuously pumped CO2 amplifier may be used in the laser system (402). Alternatively, the laser may be configured as a so-called "self-targeting" laser system, in which case a droplet acts as a mirror of the laser's optical cavity.

[0053] In some embodiments, other types of lasers may be suitable depending on the application, such as excimer lasers or molecular fluorine lasers operating at high power and high pulse repetition rates. Some examples may be suitable solid-state lasers with fiber-type, rod-type, slab-type, or disk-type active media; other laser hierarchies having one or more chambers, such as an oscillation chamber and one or more amplification chambers (the amplification chambers may be configured in parallel or series); master oscillator / power oscillator (MOPO) configurations; master oscillator / power ring amplifier (MOPRA) configurations; or solid-state lasers seeding one or more excimer, molecular fluorine, or CO2 amplifiers or oscillation chambers. Other suitable designs are anticipated.

[0054] In some embodiments, the source material may be irradiated first with a pre-pulse and then with a main pulse. The pre-pulse and main pulse seeds may be generated through a single oscillator or two separate oscillators. One or more common amplifiers may be used to amplify both the pre-pulse seed and the main pulse seed. In some embodiments, separate amplifiers may be used to amplify the pre-pulse and main pulse seeds.

[0055] In some embodiments, the source (SO) may include a beam conditioning unit (406) having one or more optics for beam conditioning, such as expanding, steering, and / or focusing the beam between the laser system (402) and the irradiation area (404). For example, a steering system that may include one or more mirrors, prisms, lenses, etc., may be provided and arranged to steer the laser focus spot to various positions within the chamber (312). For example, the steering system may include a first planar mirror mounted on a tip-tilt actuator (the tip-tilt actuator may independently move the first mirror in two dimensions) and a second planar mirror mounted on a tip-tilt actuator (the tip-tilt actuator may independently move the second mirror in two dimensions). Using the described configuration(s), the steering system may controllably move the focus spot in a direction substantially orthogonal to the beam propagation direction (beam axis or optical axis).

[0056] The beam conditioning unit (406) may include a focusing assembly that focuses the beam onto the irradiation area (404) and adjusts the position of the focus spot along the beam axis. An optical device, such as a focusing lens or a mirror, may be used for the focusing assembly. Such an optical device may be connected to an actuator to move in a direction along the beam axis so as to move the focus spot along the beam axis.

[0057] In some embodiments, the source (SO) may include a source material delivery system (408) for delivering a source material, such as a tin droplet, to an irradiation area (404), where the droplet may interact with a light pulse from a laser system (402) to generate plasma and produce EUV emission. The source material delivery system (408) may also be referred to as a material delivery system or a target material delivery system. The EUV emission is used to expose a substrate, such as a resist-coated wafer, in an exposure device (36). Details regarding various droplet distributor configurations can be found, for example, in U.S. Patent No. 7,872,245, issued January 18, 2011 (“System and method for delivering target material in a laser-generated plasma EUV light source”), U.S. Patent No. 7,405,416, issued July 29, 2008 (“Method and apparatus for delivering target from an EUV plasma source”), U.S. Patent No. 7,372,056, issued May 13, 2008 (“System for delivering target material from an LPP EUV plasma source”), and international application WO 2019 / 137846, published July 18, 2019 (“Apparatus and method for controlling droplet aggregation in a droplet stream”), the contents of all of these patents are incorporated herein by reference.

[0058] In some embodiments, the source material generating the EUV light output for substrate exposure may include, but is not limited to, a material comprising tin, lithium, xenon, or a combination thereof. The source material may be in the form of a liquid droplet and / or solid particles contained within the liquid droplet. For example, elemental tin may be used as pure tin, as a tin compound (e.g., as SnBr4, SnBr2, SnH4), or as a tin alloy (e.g., as a tin-gallium alloy, a tin-indium alloy, a tin-indium-gallium alloy, or any combination thereof). Depending on the material used, when the source material is sent to the irradiation area (404), it may be at various temperatures, e.g., room temperature or a temperature close to room temperature (e.g., tin alloy, SnBr4), an elevated temperature (e.g., pure tin), or a temperature below room temperature (e.g., SnH4).

[0059] In some embodiments, the source (SO) may include a controller (410) and / or a drive laser control system (412) to control a device in the laser system (402) to generate a light pulse to be delivered into the chamber (312) and / or to control the movement of an optical device in the beam conditioning unit (306). The source (SO) may also include a droplet position detection system that may include one or more droplet imagers (414), which provides an output signal indicating the position of one or more droplets (e.g., to ensure that the droplets reach the target in the irradiation area (404)). The droplet imager (414) may provide a measurement output to a droplet position detection feedback system (416). The droplet position detection feedback system (416) may calculate the droplet position and trajectory and, from thereon, calculate the droplet error (e.g., per droplet or on average). Then, such droplet error may be provided as input to a controller (410), and the controller (410) may, for example, provide position, direction, and / or timing correction signals to a laser system (402) to control laser trigger timing and / or control the movement of an optical device within a beam conditioning unit (406), for example, change the position and / or focus power of an optical pulse delivered to an irradiation area (404) within a chamber (312). Additionally, the source material delivery system (408) may include a control system operable to correct the error of the droplet reaching the irradiation area (404) by modifying the emission point, initial droplet stream direction, droplet emission timing, and / or droplet modulation in response to a signal from the controller (410) (which in some embodiments may include the droplet error described above or a specific amount derived therefrom).

[0060] In some embodiments, the source (SO) may include a collector (358) and a gas distribution device (420). The gas distribution device (420) may distribute gas from the source material delivery system (408) to the path of the source material (e.g., an irradiation area (404)). The gas distribution device (420) may include a nozzle through which the distributed gas can escape. The gas distribution device (420) may be structured so that when placed near the optical path of the laser system (402), light from the laser system (402) can reach the irradiation area (404) without being blocked by the gas distribution device (420) (e.g., having an aperture). A buffer gas, such as hydrogen, helium, argon, or a combination thereof, may be introduced into the chamber (312). The buffer gas may be present in the chamber (312) during plasma discharge and may serve to slow down the velocity of plasma-generating ions, reduce degradation of the optical device, and / or increase plasma efficiency. Alternatively, a magnetic field and / or an electric field (not shown) may be used alone, or in combination with a buffer gas to reduce damage caused by high-speed moving ions.

[0061] In some embodiments, the collector (358) may be a near-perpendicular incident collector mirror having a reflective surface in the shape of a long-rotation ellipsoid as described above. The collector (358) may be formed with an aperture so that a light pulse generated by the laser system (402) can pass through and reach the irradiation area (404). The same or another aperture may be used to allow gas from the gas distribution device (420) to flow into the chamber (312). As illustrated, the collector (358) may be a long-rotation ellipsoid mirror having a first focus, for example, within or near the irradiation area (404), and a second focus in an intermediate area (318) where the EUV light can be delivered to the exposure device (356). It should be understood that other optics may be used instead of a long-rotation ellipsoid mirror to collect the light and direct it to an intermediate location for delivery to a device utilizing the EUV light. In addition, the structure and function described with reference to FIG. 3 are expected to be usable with collectors other than collector (358) (e.g., collector (CO) (Fig. 2a)).

[0062] Exemplary jet / cone flow generator

[0063] The buffer gas provided by the gas distribution device (420) provides other functions in addition to the functions described above. For example, consumed plasma material (e.g., liquid tin) can become a contaminant to the environment inside the chamber (312). When a buffer gas with an appropriate flow rate and directionality is generated, the viscosity of the buffer gas can be utilized to guide the consumed plasma material toward an appropriate outlet (e.g., exhaust port). Controlling the flow of the buffer gas can significantly reduce the rate at which contaminants are deposited on the surface of the chamber (312).

[0064] Protection of the collector (358) is also a function provided by the buffer gas. Protection of the collector (358) can be achieved by a combination of buffer gas flows including umbrella flow, circumferential flow, and conical flow. Conical flow may be the most dominant in protecting the collector (358) because it may be the fastest moving flow among the flows and applies pressure directly to the droplet material as described above.

[0065] FIG. 5 illustrates a jet flow generator (516) for use with a radiation source (500) according to some embodiments. The radiation source (500) includes a collector (502), an optical system (504) having one or more optical elements (508), an illumination beam (510) for irradiating a target droplet material to generate plasma, an aperture (512) for passing a gas flow and a radiation beam (510), and a flow control structure (513).

[0066] In some embodiments, a buffer gas may be supplied to the plasma region of the radiation source (500). Various configurations are anticipated for delivering the buffer gas (e.g., hydrogen) to the irradiation region. Depending on the arrangement of the buffer gas source, one or more optical elements (508) may affect the gas flow path and may hinder the delivery of the buffer gas to the irradiation (e.g., turbulence caused by physical obstacles in the path of the gas). If the configuration of one or more optical elements (508) is static, turbulence can be managed by carefully arranging the path of the gas flow. However, as the optical source changes and evolves, it is expected that newer and different optical configurations of one or more optical elements (508) may be implemented. Changing the configuration of one or more optical elements (508) may alter the gas flow and adversely affect the flow performance of the buffer gas. Therefore, it is desirable to provide a gas flow system capable of adapting to changes in the hardware structure within the radiation source.

[0067] In some embodiments, the jet flow generator (516) may include a flow injector (518) and a diffuser (520). The flow injector (518) and the diffuser (520) may have a ring-shaped structure (see description and drawing of FIG. 7). The flow injector (518) and the diffuser (520) may output buffer gases such as hydrogen, helium, argon, and nitrogen, which are used to solve problems regarding EUV plasma materials as described herein. The directionality of the initial output from the jet flow generator (516) is indicated by the arrows of the high-speed output (522) and the diffuse output (524). The high-speed output (522) may be oriented radially inward toward the axis (526). The axis (526) may be aligned with the irradiation area or primary focus of the radiation source (500). The radiation beam (510) can be directed substantially parallel to an axis (526) that aligns with the irradiation area where the radiation beam (510) meets the droplet to generate plasma. The pressure difference (523) can be set so that the high-speed output (522) can be further tilted according to the pressure difference (523) in addition to the radial inner component (e.g., to have more of a vertically upward component) (e.g., using a vacuum). In this way, a jet flow (528) can be generated that is output toward the irradiation area through the aperture (512).

[0068] In some embodiments, the diffuser (520) may initially generate a diffuse output (524) along a direction substantially anti-parallel to the jet flow (528) (e.g., downward toward the optical system (504) and away from the collector (502)). The pressure difference giving the jet flow (528) its directionality may also be used to draw the diffuse output (524) toward the axis (526), ​​i.e., radially inward. As described in more detail below in relation to other drawings, the diffuse output (524) may be combined with a high-speed output (522) to control the diffusion of the jet flow (528). The jet flow generator (516) may include a flow distributor that distributes the input gas load to the flow injector (518) and the diffuser (520). The flow distributor may be implemented as a supply unit (530 and 532) (e.g., a first and second supply unit) and a flow control unit (534). The gas load through each supply unit (530 and 532) can be controlled independently using a flow control unit (534). The flow control unit (534) can control the velocity profile of the jet flow (528) by adjusting the ratio of the portion of input gas supplied to the flow injector (518) and the portion of input gas supplied to the diffuser (520).

[0069] It must be understood that while velocity profiles and flow rates are related, they are clearly distinct, as indicated by their separate units. Velocity is measured in units of distance per unit of time (e.g., meters per second or m / s). A flow velocity profile can be considered as the distribution of velocity across the cross-section of the flow. For example, the velocity at the center of the flow (e.g., inside a duct) may be higher than the velocity at the edges of the flow (e.g., points closer to the duct walls). Flow rates, on the other hand, are measured in units of volume per unit of time (e.g., cubic feet per minute (cfm) or standard liters per minute (slm). A high flow rate (e.g., high slm) may indicate a high-speed flow. However, a high flow rate can also indicate a large volume flow at a slower velocity (e.g., a slow but large volume flow through a wide duct). While achieving a high flow rate can be relatively simple (e.g., by expanding the cross-section of the flow or increasing the pressure), controlling the velocity profile of a jet flow can be difficult.

[0070] The embodiments disclosed herein can achieve control of the velocity profile of a jet flow through a jet flow generator. An exemplary velocity profile is described in more detail with reference to FIG. 8, which is discussed in detail below.

[0071] In some embodiments, the flow injector (518) can shape the jet flow (528) into a conical flow. The conical flow can be obtained by adjusting the velocity profile of the jet flow (528). The flow injector (518) can be used to adjust the symmetry of the conical flow (or the symmetry of the jet flow (528) of any shape as well as the conical flow). The diffuser (520) can adjust the width of the conical flow. The flow control structure (513) can be designed to be symmetric about the axis (526). The flow control structure (513) can adjust the shape (e.g., symmetry) and / or intensity of the jet flow (528). In some embodiments, the control structure (513) can be asymmetric about the axis (526). This asymmetry can be used to tilt the jet structure, and this feature is described in more detail below with reference to FIG. 10.

[0072] FIG. 6 illustrates a jet flow generator (616) for use with a radiation source (600) according to some embodiments. The radiation source (600) includes a collector (602), an optical system (604), one or more optical elements (608), an illumination beam (610), an aperture (612), a flow control structure (613), a jet flow generator (616), a flow injector (618), a diffuser (620), a high-speed output (622), a pressure difference (623), a diffusion output (624), an axis (626), a jet flow (628), and a supply unit (630).

[0073] The jet flow (616) implements a single supply unit (630) and includes a flow splitter (636) positioned on the body or frame of the flow injector (618) and / or diffuser (620). The flow splitter (636) can receive a single gas input load from the supply unit (630) and split the gas input load. The flow splitter (636) can control the velocity profile of the jet flow (628) by adjusting the ratio of the portion of input gas supplied to the flow injector (618) and the portion of input gas supplied to the diffuser (620).

[0074] FIG. 7 shows a layout (left) and a perspective cross-sectional view (right) of a jet flow generator (716) according to some embodiments. In some embodiments, the jet flow generator (716) is depicted to correspond to the elements of FIG. 6 (e.g., a flow splitter (736) is depicted). However, it should be understood that the description of FIG. 7 may also apply to the jet flow of FIG. 5 by replacing the splitter / single-feeder configuration with a dual-feeder configuration. Therefore, unless otherwise specified, the description of the elements of FIG. 5 and 6 may also apply to the elements of FIG. 7. Among the elements appearing in FIG. 7, those corresponding to the elements of FIG. 5 and 6 may have similar reference numerals (e.g., the rightmost two digits of the reference numeral are identical). In FIG. 7, these elements may include, for example, a jet flow generator (716), a flow injector (718), a diffuser (720), a high-speed output (722), a diffusion output (724), an axis (726), a supply unit (730), and a flow splitter (736).

[0075] In some embodiments, the jet flow generator (716) may include a support (738). The support (738) may provide a frame structure for supporting the flow injector (718) and the diffuser (720). The jet flow generator (716) may also include an aperture (740). In the radiation source, the jet flow generator (716) may be positioned so that the aperture (740) aligns with the aperture (512 / 612) (Figs. 5 and 6) (e.g., at least partially overlapping). The aperture thereby allows the radiation beam (510 / 610) and the jet flow (528 / 628) (Figs. 5 and 6) to pass through without obstruction.

[0076] In some embodiments, the flow injector (718) may include a cavity (742) and / or a cavity (744) (e.g., first and second cavities of the flow injector). The cavity (742) and / or cavity (744) may be ring-shaped cavities. The ring shape of the cavity may be continuous (e.g., a continuous cavity structure) or may be implemented by including two or more segments of the ring. The cavity (742) and cavity (744) may be concentric ring-shaped cavities. The cavity (742) may have a larger ring diameter than the cavity (744) (e.g., the outer cavity is further from the center axis than the inner cavity and the inner cavity is closer to the center axis than the outer cavity). The cavity (742) can provide a pressure gradient for the flow of gas in the flow injector (716). The cavity (744) can receive the flow of gas from the cavity (742) and spread the gas flow to prevent the jet flow (528 / 628) (Figs. 5 and 6) from becoming too narrow.

[0077] In some embodiments, the flow injector may include an output (746) and / or an output (748). A pressure gradient in the flow injector (718) (e.g., created by the cavity (744)) may cause the input gas load to flow at high speed toward the outputs (746 and 748). The operating pressure may be in the range of about 150 to 20,000 Pa (e.g., at the input). The operating flow rate may be in the range of about 80 to 200 slm. If the flow rate is less than 80 slm, in some cases the jet flow alone may not be sufficient to suppress tin contamination. If the flow rate exceeds 200 slm, in some cases the jet flow easily overshoots and does not align with the dynamic gas lock flow. The peak flow velocity at the center of the jet flow may be in the range of about 200 to 400 m / s. High-speed gas flowing through the cavity (742 and / or 744) can be ejected at the output (746 and 748) to generate a jet flow (528 / 628) (Figs. 5 and 6). The output (746) may be a slit opening along the ring-shaped inner circumference of the flow injector (718). The structure of the output (746) may be a continuous slit or two or more segments of a slit (a segmented example is shown in Fig. 7). The high-speed output (722) ejected through the output (746) may be directed radially inward toward the axis (726). The output (748) may be another slit opening along the ring-shaped inner circumference of the flow injector (718). The output (748) may be positioned upward relative to the output (746) (e.g., upward, as in the direction of the jet flow (528 / 628) (Figs. 5 and 6). The role of the output (748) may be to impart additional directionality to the ejected gas.While the gas ejected from the output (746) can be directed mainly inward in the radial direction, the gas ejected from the output (748) can be directed not only inward in the radial direction but also upward in the direction of the jet flow (528 / 628) (Figs. 5 and 6) (e.g., at an angle to the gas ejected from the output (748)).

[0078] In some embodiments, the diffuser (720) may include a cavity (750) and / or a cavity (752) (e.g., first and second cavities of the diffuser). The cavity (750) and / or cavity (752) may be ring-shaped cavities. The ring shape of the cavity may be continuous (e.g., a continuous cavity structure) or may be implemented by including two or more segments of the ring. The cavity (750) and cavity (752) may be concentric ring-shaped cavities. The cavity (750) may have a larger ring diameter than the cavity (752) and may be located outside of it (e.g., the outer cavity is further from the center axis than the inner cavity and the inner cavity is closer to the center axis than the outer cavity). The diffuser (720) can accept an input gas load and generate a gas flow through the cavity (752) to the cavity (750). The cavity (752) can generate a pressure difference to guide and disperse the gas into the cavity (750).

[0079] In some embodiments, the diffuser (720) may include a spray hole (754) on a surface of the diffuser (720) facing opposite to the propagation direction of the jet flow (528 / 628) and / or the radiation beam (510 / 610) (Figs. 5 and 6) (e.g., downward). Gas from the diffuser (720) may be ejected through the spray hole (754) to produce a diffuse output (724). The diffuse gas from the spray hole (754) is deflected to drift toward a high-speed output (722) by a pressure difference, and at the output, the diffuse gas and the high-speed gas combine to form a jet flow (528 / 628) having a controllable velocity profile.

[0080] FIG. 8 shows graphs (802, 804, 806) of the velocity profiles of the jet flow for various settings of the jet flow generator according to some embodiments. In some embodiments, the vertical axis of the graph represents the velocity in normalized velocity units. The horizontal axis of the graph represents the radial distance from the center of the jet flow in normalized length units. In some embodiments, the approximate width of the "bell curve" of the velocity profile may be similar to the width of the aperture.

[0081] In some embodiments, graph (802) shows the velocity profile when the flow injector receives about 100% of the input gas load, while the diffuser receives about 0% of the input gas load. When the diffuser contribution is significantly reduced, the velocity profile of the jet flow becomes a narrow cone profile as shown in the figure. The narrow cone is narrower than that shown in graphs (804 and 806).

[0082] In some embodiments, when the injector-to-diffuser gas load ratio is adjusted to approximately 80:20, the velocity profile may resemble graph (804). When comparing graph (804) with graph (802), the velocity profile of graph (804) is slightly wider and has a dip in the center (e.g., "donut profile").

[0083] In some embodiments, when the injector-to-diffuser gas load ratio is adjusted to approximately 60:40, the velocity profile may resemble graph (806). Comparing graph (806) with graphs (802 and 804), the velocity profile of graph (806) is again wider and relatively flat (e.g., a "top hat profile"). Additional velocity profiles are expected based on other adjustments of the jet flow generator.

[0084] FIG. 9 shows a cross-section of a velocity intensity map of a jet flow (928) according to some embodiments. In some embodiments, FIG. 9 is illustrated to correspond to the elements of FIG. 5-7. Therefore, unless otherwise specified, the description of the elements of FIG. 5-7 may also apply to the elements of FIG. 9. Among the elements shown in FIG. 9, those corresponding to the elements of FIG. 5-7 may have similar reference numerals (e.g., the rightmost two digits of the reference numeral are identical). In FIG. 9, these elements may include, for example, a high-speed output (922), a diffusion output (924), an axis (926), and a jet flow (928).

[0085] In some embodiments, the velocity intensity map of the jet flow (928) corresponds to the cross-section of line AA' in FIG. 7. The velocity is represented in grayscale, with darker values ​​indicating faster velocity and brighter values ​​indicating slower velocity (values ​​are normalized to be unitless). To supply the jet flow (928), high-speed output (922) is ejected from outputs (746 and 748) ( FIG. 7). Diffusion output (924) can be supplied from diffusers (520 / 620 / 720) ( FIG. 5 to 7).

[0086] In some embodiments, a high-pressure region is formed as the flow converges toward the axis (926). A pressure difference with an upward deflection (e.g., a low-pressure region being at the top) can establish an upward direction of the jet flow (928). In FIG. 9, the velocity intensity map shows substantially the same velocity magnitude for most of the conical flow, with the velocity of the flow becoming somewhat slower toward the outer edge of the flow. This configuration corresponds to the velocity profile of graph (806) (Fig. 8).

[0087] FIG. 10 illustrates a jet flow (1028) used in a radiation source (1000) according to some embodiments. In some embodiments, unless otherwise specified, the description of the elements of FIG. 5-7 may also apply to the elements of FIG. 10. Among the elements appearing in FIG. 10, those corresponding to the elements of FIG. 5-7 may have similar reference numerals (e.g., the rightmost two digits of the reference numeral are identical). In FIG. 10, these elements may include, for example, a collector (1002) and a jet flow (1028).

[0088] In some embodiments, the radiation source (1000) can generate plasma in the irradiation area (1056). As described above, the plasma is generated by irradiating a target material (e.g., liquid tin droplet) with a high-energy light pulse. When the target material exits the plasma phase, the target material can be considered as consumed waste material and must be removed from the surroundings so that a new target material can initiate a new plasma ignition (a process that may occur periodically at high frequency). A jet flow (1028) may be used to guide the waste material toward the exhaust port (1058) to protect the collector (1002) from the waste material (contaminant).

[0089] As described above, the embodiments of the jet flow generator and flow control structure described herein can control the velocity profile, directionality, and symmetry of the jet flow. In some embodiments, the jet flow generator and / or flow control structure may be used to induce an asymmetric velocity profile to deflect the jet flow (1028) in a desired direction. The jet flow (1028) may be deflected toward the exhaust port (1058) (in the positive y direction) to minimize the travel distance of waste material from the irradiation area (1056). The jet flow (1028) may be deflected away from the exhaust port (1058) (in the negative y direction). The jet flow (1028) may be deflected toward a waste collection element or a shroud. The jet flow (1028) may be deflected in any direction. Deflecting the jet flow (1028) can reduce the risk of downstream contamination of the lithography device. The inner wall of the plasma chamber of the radiation source (1000) may be coated with a wall liner. By controlling the deflection of the jet flow (1028), the deposition of waste material can be reduced or dispersed, thereby extending the life of the wall liner.

[0090] A pressure difference may also be used to further deflect the plume of the jet flow (1028). To orient the jet flow (1028) toward the exhaust port (1058), for example, the tilt may be about 10 to about 30 degrees with respect to an axis extending along the direction of the beam radiation. The tilt may also be adjusted in an azimuth direction with respect to the axis, for example toward the exhaust port (1058), away from the exhaust port (1058), or any other direction within a 360-degree azimuth range. The jet flow generator and / or flow control structure may orient the jet flow (1028) toward the desired direction by adjusting the velocity profile. To orient the jet flow toward the exhaust port (1058), the injector-to-diffuser gas load ratio may be about 60:40 to about 80:20.

[0091] The jet flow generator (516 / 616 / 716) (Figs. 5 to 7) can significantly reduce the deposition rate of waste material compared to the performance of other gas flow generators (e.g., about 2 times).

[0092] FIG. 11 illustrates a method (1100) for controlling the velocity profile of a jet flow according to some embodiments.

[0093] In some embodiments, in operation (1102), the velocity profile of the gas jet flow is controlled using a flow injector. The structure of the flow injector may be as described above (e.g., having one or more cavities to create a pressure gradient).

[0094] In some embodiments, in operation (1104), the diffusion of the jet flow is controlled using a diffuser. The structure of the diffuser may be the same as described above (e.g., having spray holes to generate a diffusion gas output). Operation (1104) may be performed simultaneously with operation (1102).

[0095] In some embodiments, in operation (1106), the jet flow is measured to determine whether the speed profile is within a nominal range or a predetermined range (e.g., a top-hat profile). If it is not within the nominal range, operations (1102 and / or 1104) may be repeated to further fine-tune the speed profile and achieve nominal flow performance. If the speed profile is within the nominal range, the method proceeds to operation (1108) to terminate the control operation.

[0096] The method steps of FIG. 11 may be performed in any expected order and not all steps must be performed. Furthermore, the method steps of FIG. 11 described above are merely examples of steps and are not limiting. That is, additional method steps and functions are conceived based on the embodiments described with reference to FIG. 1 through 10.

[0097] Terms such as “radiation,” “beam,” “light,” and “illumination” may be used herein to denote one or more types of electromagnetic radiation, such as ultraviolet (UV) rays (e.g., having a wavelength λ of 365, 248, 193, 157, or 126 nm), extreme ultraviolet (EUV or soft X-ray) radiation (e.g., in the 5-100 nm range, having a wavelength of 13.5 nm), or hard X-rays acting at less than 5 nm, as well as particle beams such as ion beams or electron beams. Generally, radiation with a wavelength of about 400 to about 700 nm is considered visible radiation, and radiation with a wavelength of about 780 to 3000 nm (or greater) is considered IR radiation. UV refers to radiation with a wavelength of about 100 to 400 nm. In lithography, the term "UV" also applies to wavelengths that can be generated by a mercury discharge lamp: G-line 436 nm, H-line 405 nm; and / or I-line 365 nm. Vacuum UV or VUV (i.e., UV absorbed by gas) refers to radiation with wavelengths of about 100 to 200 nm. For example, radiation having wavelengths in the range of 5 to 20 nm should be understood as radiation having a specific wavelength band in which at least some parts fall within the 5 to 20 nm range.

[0098] While some aspects of the present disclosure have been described in the context of a lithography apparatus for the manufacture of ICs, it should be understood that the lithography apparatus described herein may be used in other applications, such as the manufacture of integrated optical systems, induction and detection patterns for magnetic domain memory, flat panel displays, LCDs, thin film magnetic heads, etc. Those skilled in the art will understand that, in relation to these other applications, any use of terms such as "wafer" or "die" as used herein may be considered a specific example of a more general term such as "substrate" or "target." The substrate may be processed before or after exposure, for example, in a track unit (a tool that typically applies a resist layer to the substrate and develops the exposed resist) and / or a metrology unit. Where applicable, aspects of the present disclosure may be applied to such substrate processing tools and other substrate processing tools. Furthermore, since the substrate may be processed multiple times, for example to create a multilayer IC, the term "substrate" as used herein may refer to a substrate containing layers that have already been processed multiple times.

[0099] It should be understood that the phrases or terms in this specification are intended to be descriptive, not limiting, so that they can be interpreted by a person skilled in the art in light of the teachings of this application.

[0100] The present invention has been described above with the help of functional components that exemplify the implementation of specific functions and their relationships. The boundaries of these functional components are arbitrarily defined in this specification for convenience of description. Alternative boundaries may be defined as long as the specified functions and their relationships are properly performed. Since the foregoing description of specific embodiments will sufficiently reveal the general essence of the present disclosure, it will be possible to easily modify and / or adapt these specific embodiments for various applications by applying knowledge within the art, without excessive experimentation and without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and scope of equivalents of the disclosed embodiments based on the teachings and guidelines set forth herein.

[0101] It should be recognized that the detailed description, rather than the description and abstract, is intended to interpret the claims. The description and abstract may present one or more aspects (not necessarily all) of the invention as anticipated by the inventor(s) and are therefore not intended to limit the invention and the appended claims in any way. The scope and breadth of the subject matter protected shall not be limited by any of the aforementioned aspects but shall be defined by the following claims and their equivalents.

Claims

Claim 1 A radiation source comprising: a mass transfer system configured to direct a target material toward a target area; a light source configured to irradiate a target material toward a target area to generate radiation as the output of the radiation source; and a jet flow generator configured to direct a jet flow of gas toward a target area, wherein the jet flow generator comprises: a flow injector configured to control the velocity profile of the jet flow; and a diffuser configured to control the diffusion of the jet flow. Claim 2 A radiation source according to claim 1, wherein the jet flow is a conical flow, and the flow injector is further configured to control the symmetry of the conical flow. Claim 3 In paragraph 2, a radiation source, wherein the diffuser is further configured to control the dimensions of the conical flow. Claim 4 A radiation source according to claim 1, wherein the flow injector comprises a cavity configured to create a pressure gradient for the flow of gas within the flow injector. Claim 5 In paragraph 4, the cavity is a ring-shaped cavity, a radiation source. Claim 6 In paragraph 4, the flow injector further comprises another cavity connected to the cavity by a duct, the cavity is further configured to inject a flow of gas into the other cavity, and the other cavity is configured to reduce the speed of the injected flow, a radiation source. Claim 7 A radiation source according to claim 1, wherein the diffuser comprises a spray hole configured to generate a diffused gas flow to be combined with a jet flow in the output structure of a flow injector. Claim 8 A radiation source according to claim 1, wherein the jet flow generator further comprises a flow splitter configured to control the velocity profile by adjusting the ratio of the portion of input gas supplied to the flow injector and the portion of input gas supplied to the diffuser. Claim 9 A radiation source according to claim 1, further comprising a flow control structure configured to tilt the jet flow and direct the jet flow toward the exhaust port of the radiation source. Claim 10 A jet flow generator comprising: a flow injector configured to control the velocity profile of a gas jet flow; and a diffuser configured to control the diffusion of the jet flow, wherein the jet flow generator is configured to direct the jet flow having the velocity profile toward a target area. Claim 11 A jet flow generator according to claim 10, wherein the flow injector is further configured to shape the jet flow into a conical flow and to control the velocity profile to control the symmetry of the conical flow, and the diffuser is further configured to control the dimensions of the conical flow. Claim 12 A jet flow generator according to claim 11, wherein the flow rate of the jet flow is approximately 80 to 200 liters per minute. Claim 13 In paragraph 10, the jet flow generator comprises a ring-shaped cavity configured to create a pressure gradient for the flow of gas within the flow injector. Claim 14 In paragraph 13, the flow injector further comprises another cavity connected to the cavity by a duct, the cavity is further configured to inject a flow of gas into the other cavity, and the other cavity is configured to reduce the velocity of the injected flow, a jet flow generator. Claim 15 In paragraph 10, a jet flow generator further configured such that the diffuser outputs a diffused gas flow in a direction substantially anti-parallel to the jet flow. Claim 16 In paragraph 10, the jet flow generator is configured to control the velocity profile by adjusting the ratio of the portion of input gas supplied to the flow injector and the portion of input gas supplied to the diffuser, and the velocity profile has the shape of a narrow conical profile, a donut profile, or a top-hat profile based on said ratio. Claim 17 In paragraph 10, the jet flow generator is further configured to tilt the jet flow and direct the jet flow toward the exhaust port of the radiation source. Claim 18 A method comprising: controlling the velocity profile of a gas jet flow using a flow injector comprising a cavity to create a pressure gradient for the flow of gas within the flow injector; and controlling the diffusion of the jet flow using a diffuser comprising a spray hole to create a diffused gas flow to be coupled with the jet flow in the output structure of the flow injector. Claim 19 A method according to claim 18, further comprising using a flow splitter to control the velocity profile to adjust the ratio of the portion of input gas supplied to the flow injector to the portion of input gas supplied to the diffuser. Claim 20 A method according to claim 18, further comprising measuring the velocity profile of a jet flow; and determining whether the velocity profile is within a predetermined range.

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