Shielding device and control method thereof

Abstract

A method of controlling exposure dose at a substrate using a masking device comprising a first plate and a second plate is disclosed. The method includes: providing a radiation pulse at a masking device to expose a substrate; exposing an exposure region at the substrate by moving the first plate in a first direction with respect to the center of the slit and moving the second plate in a second 5 direction, where the second direction is opposite to the first direction; keeping the amount of radiation received at the exposure area constant; and wherein moving the first plate and the second plate is defined by a velocity profile of a substrate support supporting the substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application number 22217160.5 filed on December 29, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to an apparatus and method for controlling exposure dose. In particular, the present invention relates to a shielding device and a control method thereof. The shielding device can be arranged in an illumination system. The illumination system including the shielding device can form part of a lithographic apparatus to control the exposure dose at a substrate, where the substrate is exposed at a non-constant scanning speed. Background Art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern to a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). For example, a lithographic apparatus can project a pattern (often also referred to as a "design layout" or "design") of a patterning device (e.g., a mask or reticle) supported by a mask support onto a layer of radiation-sensitive material (resist) disposed on a substrate (e.g., a wafer). A substrate support (e.g., a wafer stage or wafer holder) configured to hold the substrate (e.g., a resist-coated wafer) can be accurately moved, for example, to position different target portions in the path of a radiation beam at focused and aligned positions, thereby projecting the pattern onto the substrate.

[0005] As semiconductor manufacturing processes continue to advance, circuit element dimensions have continued to decrease, while substrate throughput has increased. This places tighter constraints on lithography systems. As substrate throughput increases, the exposure time per target area decreases. Because the total dose per target area must remain constant (to properly expose the resist), the radiation flux needs to be adjusted. This dose control is typically achieved by directly controlling the number of radiation pulses, the pulse repetition rate, and / or the intensity of the radiation pulses of the radiation system (e.g., a laser system).

[0006] Typically, the exposure radiation is provided through a slit that scans the substrate surface. The dose at the substrate is determined by the actual speed of the substrate support supporting the substrate and the exposure area of the substrate (the so-called slit). The slit is defined by the shape of the opening formed by a masking device (e.g., a masking blade disposed adjacent to the reticle) ( US2005012913 ). In particular, the position of the masking blade in the scanning direction controls the area illuminated during an exposure cycle or exposure period. Before exposing a target area, the masking blade can be set to no opening (i.e., the slit is closed) to avoid unintended exposure of the substrate. To expose the target area, the first masking blade is linearly moved away from the second masking blade (opposed to the first in a fixed position), and the masking device is opened until the maximum slit area is reached. At this point, the system is ready to expose the target area. Exposure of the target area is typically performed at a constant speed of the support stage. The first and second shielding plates are arranged to move synchronously with the patterning device so that the distance between the two plates remains constant during exposure, as disclosed, for example, in US2005157285A1. Consequently, the shape of the masking device's opening remains constant over a certain period of time (i.e., the relative positions of the shielding plates remain constant). After exposure of the target area is complete, the second shielding plate begins to move linearly toward the first shielding plate to close the opening at the end of the target area.

[0007] To achieve higher substrate throughput in lithography systems without excessive acceleration and speed of the mask and substrate supports, substrate exposure is performed at a non-constant speed, as disclosed, for example, in US Pat. No. 678,839 B2. This means that the target area is exposed not only when the substrate support is moving at a constant speed, but also during acceleration and deceleration (before and after the exposure period at a constant speed, respectively). To provide a sufficient dose at the target area, the time interval between consecutive light pulses (e.g., from an excimer laser) is inversely proportional to the speed of the substrate support. This means that even during acceleration and deceleration, the laser pulse rate is adjusted to accommodate the speed of the substrate support. Controlling the exposure dose by varying the laser output (or the output of the radiation system) in response to the speed of the substrate support can lead to instabilities or undesirable fluctuations in the laser (or radiation system). As a result, the exposure dose at the substrate may not reach the desired level for at least a portion of the target area, potentially resulting in non-yielding dies. Summary of the Invention

[0008] According to a first aspect of the present disclosure, a method for controlling an exposure dose at a substrate using a shielding device is provided, the shielding device comprising a first plate and a second plate. The method comprises: providing a radiation pulse at the shielding device to expose the substrate, exposing an exposure area at the substrate by moving the first plate in a first direction relative to a center of a slit and moving the second plate in a second direction, wherein the second direction is opposite to the first direction and maintains a constant amount of radiation received at the exposure area; and wherein the movement of the first plate and the second plate is defined by a velocity profile of a substrate support supporting the substrate.

[0009] By controlling the movement of the plate in response to the speed profile of the substrate support and / or mask support, a way of controlling the radiation dose at the substrate is provided without disturbing the radiation system. Thus, the radiation system remains stable even during exposure of a substrate with a variable support speed.

[0010] During substrate exposure, the velocity profile can include a non-constant velocity of the substrate support and / or mask support. Exposing a substrate via scanning exposure while the substrate support moves at a non-constant velocity (i.e., the support accelerates or decelerates) can be advantageous in terms of substrate throughput. Furthermore, during scanning exposure, lower acceleration and deceleration rates can be used.

[0011] The speed profile may include a sinusoidal speed profile, which may introduce less mechanical disturbance to the lithography system.

[0012] Furthermore, the amount of radiation can be controlled by an exposure control index, where the exposure control index is the number of pulses in the slit (N slit ) or radiation dose.

[0013] The method according to the first aspect is particularly useful for use in a control unit. The control unit may comprise means for setting the position of a shielding plate arranged in the shielding arrangement. The control unit is thereby operable to perform the method for controlling the exposure dose at the substrate.

[0014] According to a second aspect of the present disclosure, a shielding device for selectively shielding portions of a patterning device from a radiation beam is provided. The shielding device comprises a plurality of shielding plates that are mechanically separated from one another. A control unit is arranged to control a position of each of the plurality of shielding plates, and wherein the position of at least two of the plurality of shielding plates is defined by a velocity profile of a substrate support supporting the substrate.

[0015] During exposure of the substrate, the velocity profile may comprise a non-constant velocity of the substrate support and / or the mask support.The velocity profile may comprise a sinusoidal velocity profile.

[0016] The shielding arrangement according to the second aspect is particularly beneficial for use in an illumination system.The illumination system may be part of a lithographic apparatus.

[0017] According to a third aspect of the present disclosure, a method for controlling the position of a shielding plate of a shielding device is provided. The method comprises: receiving a first input at a control unit, the first input comprising velocity profile information of a mask support and / or substrate support to be used during exposure, receiving a second input at the control unit, the second input being an exposure control indicator, determining a position setpoint for the shielding plate during exposure, and moving the shielding plate to the determined position setpoint.

[0018] As an exposure control indicator, the number of pulses in the slit (N slit ) or radiation dose.

[0019] The method for controlling the position of the shielding plate can receive a signal corresponding to the position of the shielding plate at the control unit, which is used as a feedforward signal or a feedback signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0021] Figure 1 A schematic overview of a lithographic apparatus is depicted;

[0022] Figure 2 Depicted showing a shielding plate Figure 1 a schematic diagram of a portion of the depicted lithographic apparatus;

[0023] Figure 3A Describes the embodiment of the present disclosure that can be formed Figure 1 an exploded view of a shield arrangement of a portion of the depicted lithographic apparatus;

[0024] Figure 3B Depicts a diagram showing how openings between plates may be formed according to an embodiment of the present disclosure. Figure 1 a schematic three-dimensional overview of a shielding arrangement of a portion of the depicted lithographic apparatus;

[0025] Figure 4 illustrates the position of the mask as a function of time during a conventional exposure of a target area;

[0026] Figure 5 depicts a schematic front view of a shielding device;

[0027] Figure 6A depicting velocity profiles of the mask support and the substrate support as a function of time;

[0028] Figure 6BThe diagram shows an embodiment of the present invention. Figure 6A the position of the mask at different moments during the exposure of the target area in the case of a velocity profile of ; and

[0029] Figure 7 A schematic diagram of a method for controlling a shielding device according to an embodiment of the present invention is illustrated. DETAILED DESCRIPTION

[0030] In this document, the terms "radiation" and "beam" are used to cover all types of electromagnetic radiation, including ultraviolet radiation (e.g., having a wavelength of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and EUV (extreme ultraviolet radiation, e.g., having a wavelength in the range of about 5 nm-100 nm).

[0031] As used herein, the terms "reticle," "mask," or "patterning device" should be broadly interpreted to refer to a general-purpose patterning device that can be used to impart an incident radiation beam with a patterned cross-section corresponding to the pattern to be produced in a target portion of the substrate. The term "light valve" may also be used in this context. In addition to classical masks (transmissive or reflective, binary, phase-shift, hybrid, etc.), examples of other such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0032] To illustrate the present invention, a Cartesian coordinate system is used. A Cartesian coordinate system has three axes: the x-axis, the y-axis, and the z-axis. Each of these three axes is orthogonal to the other two. Rotation about the x-axis is called an Rx rotation. Rotation about the y-axis is called an Ry rotation. Rotation about the z-axis is called an Rz rotation. The Cartesian coordinate system is not intended to limit the present invention but is merely used to illustrate it.

[0033] Figure 1 A lithographic apparatus LA is schematically depicted. The lithographic apparatus LA comprises an illumination system (also referred to as an illuminator) IL configured to condition a radiation beam or beams LB (e.g., UV radiation, DUV radiation, or EUV radiation); a mask support (e.g., a mask table) MT configured to support a patterning device (e.g., a mask) MA and connected to a first positioner configured to accurately position the patterning device MA according to certain parameters; and a substrate support (e.g., a wafer stage) WT configured to hold a substrate (e.g., a resist-coated wafer) W. A second positioner may be provided configured to accurately position the substrate support according to certain parameters. A projection lens system (e.g., a refractive projection lens system) PL is configured to project a pattern (a patterned projection beam) imparted by the patterning device MA to the radiation beam LB onto a target portion of the substrate W (e.g., comprising one or more dies).

[0034] In operation, the illumination system IL receives a radiation beam from a radiation source SR, for example via a beam delivery system. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for directing, shaping, and / or controlling the radiation. The illuminator IL may be used to condition the radiation beam B so that it has a desired spatial and angular intensity distribution in its cross-section at the plane of the patterning device MA.

[0035] The term "projection lens system" PL as used herein should be broadly understood to cover various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and / or electrostatic optical systems, or any combination thereof, depending on the exposure radiation used, and / or other factors such as the use of immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system" PL.

[0036] The lithographic apparatus LA may be of a type in which at least a portion of the substrate may be covered by a liquid having a relatively high refractive index (e.g., water) to fill the space between the projection system PS and the substrate W, which is also known as immersion lithography. More information on immersion technology is given in US6952253 (which is incorporated herein by reference).

[0037] The lithographic apparatus LA may also be of a type having two (also referred to as "dual stage") or more substrate supports WT. In such a "multi-stage" machine, the substrate supports WT may be used in parallel, and / or steps for subsequent exposure preparation of the substrate W may be performed on a substrate W on one of the substrate supports WT while another substrate W on another substrate support WT is being used to expose a pattern on the other substrate W.

[0038] In addition to the substrate support WT, the lithographic apparatus LA may further comprise a measurement stage. The measurement stage is arranged to hold sensors and / or cleaning devices. The sensors may be arranged to measure properties of the projection system PL or properties of the radiation beam LB. The measurement stage may hold a plurality of sensors. The cleaning devices may be arranged to clean parts of the lithographic apparatus, such as a portion of the projection system PL or a portion of a system for providing immersion liquid. The measurement stage may be moved below the projection system PL when the substrate support WT is away from the projection system PL.

[0039] In operation, a radiation beam LB is incident on a patterning device (or mask) MA, which is held on a mask support MT and is patterned by a pattern (design layout) on the patterning device MA. After traversing the mask MA, the radiation beam LB passes through a projection system PL which focuses the beam onto a target portion of the substrate W. With the aid of a second positioner and a position measurement system, the substrate support WT can be accurately moved, for example, in order to position different target portions in the path of the radiation beam LB at focused and aligned positions. Similarly, a first positioner and possibly another position sensor (not shown) are provided. Figure 1 The patterning device MA (depicted explicitly in FIG) can be used to accurately position the patterning device MA relative to the path of the radiation beam LB. Mask alignment marks and substrate alignment marks can be used to align the patterning device MA and substrate W. Although the substrate alignment marks occupy dedicated target portions, they can be located in the spaces between target portions. When the substrate alignment marks are located between target portions, they are referred to as scribe lane alignment marks.

[0040] A shielding device MD is provided for selectively shielding portions of the patterning device MA from the radiation beam LB. Figure 1 (not shown in the figure), the masking device MD may be arranged to selectively mask parts of the patterned projection beam. Figure 1 As shown, relay optics (or relay lenses) RL are provided for projecting radiation passing through the shielding device to the patterning device MA.

[0041] Figure 2 Shown as Figure 1 A cross-sectional view in the yz plane of a portion of the lithographic apparatus LA is shown. A shielding device MD according to an embodiment of the present invention is schematically illustrated. Shielding device MD comprises a first shielding structure and a second shielding structure. The shielding structure may be a plate or other structure adapted to selectively (at least partially) shield the patterning device from being used. In other words, the provided radiation beam may be shielded by the shielding structure. Shielding device MD preferably comprises shielding plates 10, 11, 20, 21 arranged to form two sets of plates: X plates 20, 21 and Y plates 10, 11. The two sets of plates are mechanically separated from one another. In other words, the plates are mounted such that vibrations generated by the X plate or Y plate are not transmitted to the Y plate or X plate, and vice versa.

[0042] The shielding plates 10, 11, 20, and 21 can also be considered plates or other structures suitable for shielding. According to one embodiment of the present invention, the Y plates 10 and 11 are driven (i.e., operated to move) in the y-direction during substrate exposure, while the X plates 20 and 21 are stationary during exposure. However, the present invention is not limited in this respect, and the Y plates can also be stationary. That is, the X plates 20 and 21 can be movable while the Y plates 10 and 11 are stationary. The plates that move during scanning (hereinafter referred to as the Y plates for convenience) are controlled by software and electronics, and their positions can be adjusted by actuators. It should be noted that the X plates are similarly controlled by software and electronics (as well as actuators). Typically, the Y plates move together by a defined distance in the y-direction, which corresponds to the scanning direction (i.e., the direction in which the mask stage / mask holder MT and substrate table / substrate holder WT are moved during scanning exposure). The movable plates are controlled to move according to a desired scanning curve or trajectory.

[0043] The plates can be set so that a predetermined distance exists between the X-plates 20, 21 and between the Y-plates 10, 11. Conventionally, the Y-plates 10, 11 are arranged to be movable during scanning. While movable, the X-plates 20, 21 are typically arranged to be stationary during scanning. If the X-plates 20, 21 are to be moved, this typically occurs between scans (exposure cycles). For static exposures, the X-plates can be moved between exposures. For scanning exposures, the Y-plates 10, 11 are specifically arranged to perform additional movement, which allows the radiation beam LB to scan the patterning device MA.

[0044] refer to Figure 2 The shielding device MD, in particular the features of the shielding plates 10 , 11 , 20 and their arrangement relative to each other and other components of the lithographic apparatus, is described in further detail in US2005157285A1 , which is incorporated herein by reference.

[0045] Figure 3A and Figure 3B Depicted separately Figure 1 Exploded view and schematic three-dimensional overview of a shadow device MD of the depicted lithographic apparatus LA. These figures provide examples of arrangements of plates 10, 11, 20, 21 relative to each other. Double-headed arrows illustrate the direction of movement of each plate.

[0046] like Figure 3BAs shown, plates 10, 11, 20, and 21 can be positioned so as to form an opening 30 between them. Through opening 30, a portion of radiation beam LB provided by illuminator IL can pass through shielding device MD and toward relay lens RL. The size of the radiation passage area 30 defined by the opening between the plates determines the so-called scanning slit shape. By controlling the position of the plates, the size of opening 30 (or passage area) can be controlled. Thus, the amount of radiation that passes through shielding device MD to interact with patterning device MA can be controlled and defined. Furthermore, the position of opening 30 is determined by the position of each plate. The plate positions can be set using a controller.

[0047] Figure 4 The diagram illustrates the position of the plates relative to the center of the slit (opening) 30 during a conventional exposure cycle of a target area of a substrate. The solid lines denoted by reference numerals 50 and 51 indicate the position of the first plate (first Y-plate) 11 over time. The dashed lines denoted by reference numerals 52 and 53 indicate the position of the second plate (second Y-plate) 10 over time. At the start of the exposure cycle, both plates are at the same y-position, indicated by the intersection of the solid and dashed lines (located at the lower left of the diagram). This means that before the exposure cycle begins, the plates are positioned to prevent any radiation from impinging on the patterning device MA. At the start of the exposure cycle, the first plate 11 moves to a defined distance from the second plate 10 (as indicated by the first portion of the solid line 50) to form the opening 30. Once the opening 30 is formed (at the starting position of the solid line denoted by reference numeral 51), the actual exposure is performed. At the end of the exposure (at the end position indicated by dashed line 52), the second plate (second Y plate) 10 is moved (towards the first plate 11) to a position that prevents radiation from impinging on the patterning device MA, as indicated by dashed line 53. Thus, at the end of the exposure cycle, the opening 30 is closed so that no radiation impinges on the patterning device MA.

[0048] During conventional exposure, the Y plates 10, 11 are kept at a constant distance from each other (i.e., a constant slit width), as shown in FIG. Figure 4 As shown by the solid lines 51 and dashed lines 52 in FIG. 4 , the size of the area where the radiation impinges on the patterning device remains constant. Note that the patterning device MA is exposed by the radiation beam LB passing through the openings between the plates 10, 11, 20, 21 while moving at a predetermined constant scanning speed.

[0049] To achieve higher throughput, the speed (or scanning speed) of the mask support MT and substrate support WT during exposure needs to be increased. Consequently, the accelerations, and the power required to achieve these accelerations, need to be significantly increased to achieve a constant high speed during exposure. Furthermore, the wafer stage trajectory may also introduce unwanted vibrations in the system. To minimize these vibrations, sudden changes in acceleration and deceleration need to be avoided. This can be achieved by making the velocity profile of the stages MT and WT a continuous or smooth curve (e.g., an arc-shaped curve). Such a velocity profile can be a non-constant speed. As disclosed, for example, in US Pat. No. 5,995,203A, substrate exposure can be performed during acceleration and deceleration of the stages. The speeds of the mask support MT and substrate support WT can be described as sinusoidal curves without a constant speed region. Note that similar velocity profiles with a constant speed region can be used. For these exposure settings, the opening and closing of the plates 10 and 11 (as described above) occurs at increased acceleration and speed of the plates. This can introduce additional vibrations or disturbances.

[0050] Radiation dose control is typically performed by means of multiple (inline) radiation detectors, uniformity correction using gray filters, or attenuation fingers. The goal of dose control is to provide a constant amount of energy uniformly across the substrate W. For radiation dose control, at constant radiation power and attenuation, varying scan speed (or speed of the mask support MT and substrate support WT) can lead to undesirable variations in the radiation dose in the field of the substrate W and / or on the die.

[0051] When exposure is performed at a non-constant stage speed, the radiation dose received by the exposed area varies from area to area. In other words, the radiation dose received by the exposed area depends on the actual stage speed. This means that, if radiation source SR provides a constant radiation dose, a first area exposed at a relatively low stage speed will receive a higher dose than a second area exposed at a relatively high stage speed. Therefore, without any countermeasures, the introduction of a non-uniform speed profile will result in a radiation dose variation at substrate level that is inversely proportional to the stage speed.

[0052] By adjusting the amount of radiation provided by the radiation source SR to suit the speed of the table MT, WT, variations in the radiation dose over the exposure area can be prevented or minimized. Adjustment of the radiation amount can be achieved by controlling the radiation source output. For example, the radiation amount can be adjusted by modulating the radiation power, the interval between radiation pulses (e.g., laser pulses), or a combination of both, as disclosed in US Pat. No. 5,995,203A. This control can be provided by a feedback control loop or a feedforward control loop. Typically, the radiation output of the radiation source SR is synchronized with the speed of the table MT, WT.

[0053] The inventors have recognized that modulating the radiation source SR in response to the stage velocity may require the radiation source SR to have a relatively large dynamic range in terms of output power and pulse modulation, which can lead to instabilities in the radiation source SR. Instabilities can result in uncontrolled variations in the energy, wavelength, and / or bandwidth of the radiation beam. For some types of sources, such as excimer lasers, performance is limited only for a constant repetition rate of the radiation pulses. To ensure the performance of the radiation source SR, it is preferable to minimize modulation of the radiation source.

[0054] According to an embodiment of the present invention, the amount of radiation that impinges on the patterning device MA is controlled by controlling the amount of radiation that passes through the mask device MD, thereby controlling the amount of radiation used to expose the substrate W. More specifically, during scanning exposure of the substrate W, radiation dose control is provided by the first and second Y plates 10 and 11 in response to the speed of the mask support MT and / or the substrate support WT.

[0055] As described above, the amount of radiation reaching the exposure area at the substrate is clearly limited by plates 10, 11, 20, 21. By varying the insertion of Y plates 10, 11 according to the field position during scanning exposure (e.g., the field position of the exposure area at substrate W and / or patterning device MA) or the timing of the exposure cycle, opening 30 can be manipulated to control the radiation dose. Thus, the movement of the Y plates varies with the speed profile of mask support MT and / or substrate support WT.

[0056] According to an embodiment of the present invention, a method of controlling the shielding device is provided which determines and sets the position of the Y plates 10, 11 as a function of time (during an exposure period), whereby the control method aims to keep the number of radiation pulses in the slit constant. The number of pulses in the slit is referred to as N slit This indicator represents the number of radiation pulses received by each "pixel" of the substrate. During the scanning exposure, N slit The higher the value, the more pulse averaging occurs. This can lead to better dose performance of the exposed area on the substrate W.

[0057] According to another embodiment of the invention, a method of controlling a shielding arrangement is provided which determines and sets the position of the Y plates 10, 11 as a function of time (within an exposure period), whereby the control method is arranged to keep the radiation dose in the slit constant.

[0058] The two control methods described above (using N slit or dose as an exposure control indicator) utilizes the Y plates 10, 11 of the masking device MD. This makes the shape or size of the opening 30 non-constant during the exposure cycle (especially during the exposure of the substrate W), which will be explained in more detail below.

[0059] Figure 7 A method of controlling 100 a masking device according to an embodiment of the invention is schematically illustrated. A controller (or control unit) 103 is arranged to receive a first input 101 comprising information on a velocity profile of the mask support MT and / or substrate support WT to be used during exposure (exposure cycle). Based on the first input 101, set points for the plates 10, 11, 20, 21 are defined. As described above, N slit or dose as an exposure control indicator. The exposure control indicator is received or provided via the second input 102. Based on the received first input 101 and second input 102, the control unit 103 calculates / determines the set point of the plate during exposure. The set point can be stored in a memory (for example, in the form of a lookup table). The control unit 103 instructs one or more actuators 104 by providing a signal (voltage or current signal) to set or move the plates 105 (10, 11) of the masking device MD to a desired (calculated / determined) position. Since the mask support MT and the substrate support WT (also referred to as the stage) are continuously moving during scanning exposure (especially during scanning exposure without a velocity profile), the controller 103 continuously instructs the actuators 104 to synchronize the movement of the Y plates 10, 11 with the movement of the stage and its velocity profile (first input 101).

[0060] Each plate may be connected to at least one actuator.

[0061] According to another embodiment of the method for controlling the masking device 100, the control unit 103 may also receive a panel position signal 106. The panel position signal 106 includes information about the actual position of the panel 105, which can be used to calculate / determine a panel setpoint during exposure. The panel position signal 106 can be used as a feedforward signal or a feedback signal. The panel position information can be provided by one or more position sensors disposed on the panel 105. These sensors can be electromechanical, magnetic, inductive, capacitive, photoelectric, and / or ultrasonic sensors.

[0062] Note that the first signal 101 may include position information of the stage (mask support MT, substrate support WT) to ensure that the position of the Y-plates 10, 11 is synchronized with the stage position. The controller may use the stage position information received via the first input and the plate position information received via the plate position signal 106 to set and control the plate 105 via commands sent to the actuator 104.

[0063] The method of controlling the shielding device may use or include a controller (or control unit) to define and control the position setting and movement of the shielding plates 10, 11, 20, 21. The controller may receive one or more signals corresponding to the speed of the mask support MT and / or the substrate table. The one or more signals may be provided by one or more stage controllers.

[0064] Furthermore, a radiation detector may be provided downstream of the shielding device MD to measure and monitor the radiation dose and the radiation pulse rate passing through the shielding device MD. The radiation detector may be arranged to provide a detector signal to the controller, wherein the detector signal includes information about the measured radiation dose and / or radiation pulse rate.

[0065] One or more radiation detectors may be provided. One or more radiation detectors may be arranged on the relay optics RL, the mask support MT, the projection system PL and / or the substrate support WT. Each radiation detector may provide a signal to the controller. A signal corresponding to the amount of radiation dose measured by the one or more radiation detectors may be provided as a third input to the control unit 103 ( Figure 7 (not shown in the figure).

[0066] In an embodiment, the method comprises adjusting radiation characteristics of the radiation source. The radiation characteristics may include pulse length, pulse energy and pulse repetition rate.

[0067] Figure 5 The shielding plates 10, 11, 20, 21 of the shielding device MD are schematically shown from different angles. The angles are, for example, at the radiation beam LB in the illuminator IL (e.g. Figure 3B shown).

[0068] Figure 6A Depicts the high acceleration and velocity (mask support velocity V) without the need for a mask support. MT ) and excessive acceleration and velocity of the substrate support (substrate support velocity V WT ), a speed profile of the mask support MT and the substrate support WT that can achieve a high substrate (wafer) throughput of the lithography system. During the exposure cycle as shown in the gray filled area in the figure, both stages (mask support MT and substrate support WT) perform substrate exposure at a non-constant (or non-uniform) speed. Although a sinusoidal speed profile is shown in this example, other speed profiles that deviate from the sinusoidal curve can also be used for the same purpose. It will be clear to those skilled in the art that the present invention is not limited to the mask support speed V MT and substrate speed V WT Note that for an exposure system with a magnification of 1:4, the speed of the mask support MT is four times that of the substrate support WT.

[0069] Figure 6B Depicts a process according to an embodiment of the present invention where both the mask support MT and the substrate support WT follow a sinusoidal velocity profile ( Figure 6A ), the position of the mask at different times during the exposure of the target area. During the exposure (e.g., Figure 6A The positions of the first plate 11 and the second plate 10 over time are shown as dashed trajectory 11a and solid trajectory 10a, respectively. Figure 5 A similar perspective is shown illustrating the positions of the two plates during an exposure cycle.

[0070] refer to Figure 6A and Figure 6B , the trajectories of the two plates relative to the slit center are plotted as a function of time. Figure 6B The illustrations near the graphs in the diagram provide an overview of the Figure 6A More insight into the plate position and movement during exposure of the non-constant velocity profile is described:

[0071] At the beginning of an exposure cycle (or exposure cycle), the two Y plates 10 and 11 are positioned so that there is no opening between them. The location of the slit area 30 is indicated by the dashed rectangle 31 (maximum slit area), while the center 32 of the slit area is indicated by the dashed line. Opening 30 is achieved by moving the first plate 11 upward (as indicated by the upward arrow) and the second plate 10 downward (as indicated by the downward arrow). Consequently, the Y plates 10 and 11 move away from each other.

[0072] II - The speed of the mask support and substrate support continues to increase. As the first plate 11 continues to move upwards and further away from the slit center 32 (albeit at a lower speed), the opening 30 becomes larger, and the second plate 10 continues to move downwards (also away from the slit center).

[0073] III and IV - At half the exposure time, the stages are approaching their maximum speed. Before the stages reach their maximum speed (acceleration decreases), the second plate 10 is in its end position relative to the center of the slit, as shown in III. After the stages have reached their maximum speed, they begin to decelerate and their speed decreases. The first plate 11 reaches its end position relative to the center of the slit, as shown in Figure 6B In this time window, the opening 30 (slit region) is at its maximum width.

[0074] V - Later in the exposure cycle, the stage continues to decelerate (stage speed decreases). The first and second plates move towards the center of the slit 32 and relatively towards each other.

[0075] VI - At the end of the exposure period, both the first plate 11 and the second plate 10 are positioned so that there is no opening between the two plates 10, 11. No more radiation passes through the shielding device MD.

[0076] The trajectory of the Y-plate (shown as solid line 10a and dashed line 11a) is governed by the velocity profile and control specifications of the stages (mask support MT and substrate support WT). These two trajectories (and Figure 6B , as highlighted in the inset in FIG, shows that the shape of the opening 30 (i.e., the slit shape) is not constant during the exposure period when the stage follows a non-constant velocity profile (e.g., a sinusoidal velocity profile). Furthermore, although the first and second plates 11 and 10 are designed to remove (or block) energy symmetrically from both sides of the slit based on field position, the slit becomes asymmetrical due to the nonlinear movement of the mask support MT and substrate support WT.

[0077] As described above, according to an embodiment of the present invention, the position or trajectory of each Y-plate 10, 11 depends on the velocity profile of the stage (mask support MT and substrate support WT), such as Figure 6B According to conventional methods, the position or trajectory of each plate is independent of the stage speed, as shown in Figure 4 By comparing the two figures, we can see that the conventional method ( Figure 4 ) and the present invention ( Figure 6B ) between the two groups, with a clear difference in the plate trajectory.

[0078] According to an embodiment of the present invention, a method for controlling the exposure dose at a substrate W using a shielding device MD is provided, wherein the shielding device MD includes a first plate 11 and a second plate 10, and the method includes: providing a radiation pulse at the shielding device MD to expose the substrate W through a scanning slit; exposing an exposure area at the substrate W by moving the first plate 11 and the second plate 10 independently of each other; keeping the amount of radiation received at the exposure area constant; and wherein the first plate and the second plate move according to a speed curve of a substrate support WT supporting the substrate W.

[0079] The number of pulses in the slit (N slit ) is kept constant to control and obtain a constant amount of radiation received at the exposure area. A controller 103 may be arranged that controls the position of the panel as N slit and the mask support speed V MT and / or substrate support speed V WT In this arrangement, N slit is set as a control indicator.

[0080] Due to the pulse-to-pulse randomness, the dose accuracy is 1 / sqrt(N slit ) scaling. Therefore, it is desirable to maintain Nslit Constant.

[0081] According to another arrangement, the amount of radiation received at the exposure area may be controlled and obtained to be constant by keeping the radiation dose constant. A controller 103 may be arranged which controls the plate position as a function of the radiation dose and the mask support speed V MT and / or substrate support speed V WT In this arrangement, the radiation dose is set as a control index.

[0082] According to an embodiment of the invention, during exposure of the substrate the velocity profile of the substrate support WT comprises (at least) a non-constant velocity.The velocity profile comprises (at least partially) a sinusoidal velocity profile.

[0083] According to another embodiment of the present invention, the first plate 10 moves along a first direction relative to the center of the scanning slit, and the second plate 11 moves along a second direction opposite to the first direction.

[0084] Although N can be used slit While the exposure dose at the exposure area can be controlled by modulating the radiation source SR in response to the stage speed as an additional control parameter, it may be advantageous to control the exposure dose at the exposure area. Thus, the exposure dose is controlled not only by the Y plate position but also by the output of the radiation source SR. Consequently, the output of the radiation source SR may vary in terms of pulse repetition rate, number of pulses, and / or intensity. This additional control parameter allows for optimized control and a more flexible control approach.

[0085] According to an embodiment of the present invention, a controller (or control unit) 103 is provided, which is operable to perform the method of controlling the exposure dose at the substrate W as described above. The controller may receive one or more signals (or information) during an exposure cycle, wherein the one or more signals include the following information: mask support speed V MT , substrate support speed V WT , radiation dose, radiation pulse characteristics (eg pulse length, pulse energy, pulse repetition rate), position of the shield, position of the mask support MT, position of the substrate support WT. The one or more signals may be provided by a sensor or detector.

[0086] The controller may include means for setting and adjusting the position of the shielding panels in response to one or more received signals (information). Adjustments to the panels may be made by actuators controlled by the controller 103. The controller 103 may be part of the shielding device MD or be arranged at the shielding device MD.

[0087] Those skilled in the art will appreciate that the control unit (controller) 103 may control the positions of the X plates 20, 21 in response to input signals. However, during exposure of the substrate W, the positions of the X plates 20, 21 may be constant.

[0088] The controller may include means for setting and adjusting radiation pulse characteristics (eg pulse length, pulse energy, pulse repetition rate) of the radiation source SR.

[0089] According to an embodiment of the present invention, a lithographic apparatus LA is provided. The apparatus is configured to expose a semiconductor substrate using radiation. The apparatus comprises an illuminator IL, a masking device MD, a mask support, a projection system PL, and a substrate support WT. Furthermore, the apparatus LA may include a controller configured to control an exposure dose at the substrate W.

[0090] One or more detectors and / or sensors may be arranged in the lithographic apparatus LA to provide one or more signals to the controller. The one or more signals that may be provided by the one or more detectors and / or sensors include the following information: mask support speed V MT , substrate support speed V WT , radiation dose, radiation pulse characteristics (e.g. pulse length, pulse energy, pulse repetition rate), position of the shielding plates, position of the mask support MT, position of the substrate support WT. For example, one or more detectors and / or sensors may be arranged at the shielding device MD to measure the position of the plates and their speed.

[0091] It will be appreciated by those skilled in the art that features of different aspects of the present invention as described above may be combined together.

[0092] Although specific reference may be made herein to the use of lithographic apparatus in the manufacture of integrated circuits, it should be understood that the lithographic apparatus described herein may have other applications. Other possible applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

[0093] Although embodiments of the present invention may be specifically referenced herein in the context of lithographic equipment, embodiments of the present invention may be used in other equipment. Embodiments of the present invention may form part of mask inspection equipment, metrology equipment, or any equipment that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These equipment are generally referred to as lithographic tools. Such lithographic tools may utilize vacuum conditions or ambient (non-vacuum) conditions.

[0094] Where appropriate, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented by instructions stored on a machine-readable medium, which 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 storage media; optical storage media; flash memory devices; electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and the like. Furthermore, firmware, software, routines, and instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are for convenience only and that these actions are in fact performed by a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., and that the execution of such actions may cause actuators or other devices to interact with the physical world.

[0095] Various aspects of the invention are set out in the following clauses.

[0096] 1. A method for controlling an exposure dose at a substrate using a shielding device, the shielding device comprising a first plate and a second plate, the method comprising: providing a radiation pulse at the shielding device to expose the substrate; exposing an exposure area at the substrate by moving the first plate in a first direction relative to a center of a slit and moving the second plate in a second direction, the second direction being opposite to the first direction; maintaining a constant amount of radiation received at the exposure area; and wherein moving the first plate and the second plate is defined by a velocity profile of a substrate support supporting the substrate.

[0097] 2. The method of clause 1, wherein the velocity profile comprises a non-constant velocity of the substrate support.

[0098] 3. A method according to clause 1 or 2, wherein the speed profile comprises a sinusoidal speed profile.

[0099] 4. A method according to any one of clauses 1 to 3, wherein the amount of radiation is controlled by an exposure control index.

[0100] 5. The method of clause 4, wherein the exposure control indicator is N slit or dosage.

[0101] 6. A control unit comprising means for setting a position of a shielding plate arranged in a shielding arrangement, wherein the control unit is operable to perform the method of controlling exposure dose according to any one of clauses 1 to 5.

[0102] 7. The control unit according to clause 6, further comprising means for setting and adjusting the radiation (pulse) characteristics of the radiation source used during exposure of the substrate.

[0103] 8. A shielding device for selectively shielding portions of a patterning device from a radiation beam, comprising: a plurality of shielding plates, each shielding plate being mechanically separated relative to one another; a control unit arranged to control a position of each of the plurality of shielding plates; and wherein the position of at least two of the plurality of shielding plates is defined by a velocity profile of a substrate support supporting a substrate.

[0104] 9. A shielding arrangement according to clause 8, wherein the speed profile comprises a non-constant speed.

[0105] 10. A screening arrangement according to clause 8 or 9, wherein the velocity profile comprises a sinusoidal velocity profile.

[0106] 11. An illumination system comprising a shielding arrangement according to any one of clauses 8 to 10.

[0107] 12. An exposure apparatus (or lithographic apparatus) comprising an illumination system according to clause 11.

[0108] 13. A method for controlling the position of a shielding plate of a shielding device, comprising: receiving a first input at a control unit, the first input comprising information of a speed curve of a mask support and / or substrate support to be used during exposure; receiving a second input at the control unit, the second input being an exposure control indicator; determining a position set point of the shielding plate during exposure; and moving the shielding plate to the determined position set point.

[0109] 14. The method of clause 13, wherein the exposure control indicator is N slit or dosage.

[0110] 15. The method of clause 13 or 14, further comprising receiving a shutter position signal at the control unit, the shutter position signal being used as a feedforward signal or a feedback signal.

[0111] 16. A method according to any of clauses 13 to 15, wherein moving the shield plate is performed by instructing one or more actuators connected to the shield plate.

[0112] 17. A controller arranged to slit and the mask support speed and / or the substrate support speed to control the position of the shield plate, where N slit It is a control indicator.

[0113] 18. A controller arranged to control the position of a shield plate as a function of radiation dose and mask support speed and / or substrate support speed, wherein the radiation dose is the control indicator.

[0114] 19. A controller according to clause 17 or 18, wherein the velocity profile of the substrate support comprises at least a non-constant velocity during exposure of the substrate.

[0115] 20. A controller according to clause 19, wherein the speed profile at least partially comprises a sinusoidal speed profile.

[0116] 21. The exposure apparatus of clause 12, being a lithographic apparatus, further comprising a mask support, a projection system and a substrate support.

[0117] 22. An exposure apparatus according to clause 12 or 21, comprising one or more detectors to provide one or more signals to the control unit.

[0118] 23. An exposure device according to item 22, wherein the one or more signals provided by the one or more detectors include information about the speed of the mask support, the speed of the substrate support, the radiation dose, the characteristics of the radiation pulse, the position of the shielding plate, the position of the mask support or the position of the substrate support.

[0119] 24. A controller according to any of clauses 17 to 20, further comprising means for setting and adjusting the radiation characteristics of the radiation source.

[0120] 25. The method of any one of clauses 1 to 5, further comprising controlling the output of a radiation source providing the radiation pulses.

[0121] 26. The method of any one of clauses 1 to 5 and 25, further comprising adjusting the radiation characteristics of the radiation source.

[0122] 27. A screening arrangement according to any of clauses 8 to 12, 21 and 22, further comprising an actuator for moving the plurality of panels.

[0123] 28. A screening arrangement according to any of clauses 8 to 12, 21, 22 and 27, further comprising one or more detectors for measuring the position and / or speed of the screening plate.

[0124] While specific embodiments of the present invention have been described above, it will be appreciated that the present invention may be implemented in other ways than those described above. The foregoing description is intended to be illustrative, not restrictive. Therefore, it will be appreciated by those skilled in the art that modifications may be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A method for controlling an exposure dose at a substrate using a shielding device, the shielding device comprising a first plate and a second plate, the method comprising: providing a radiation pulse at the shielding device to expose the substrate; The exposure area of the substrate is exposed by the following operations: moving the first plate in a first direction relative to the center of the slit, and moving the second plate in a second direction, the second direction being opposite to the first direction; maintaining a constant amount of radiation received in the exposure area; as well as Wherein movement of the first plate and the second plate is defined by a velocity profile of a substrate support supporting the substrate. 2 . The method of claim 1 , wherein the velocity profile comprises a non-constant velocity of the substrate support. The method according to claim 1 , wherein the speed profile comprises a sinusoidal speed profile.

4. The method according to any one of claims 1 to 3, wherein the radiation amount is controlled by an exposure control index.

5. The method according to claim 4, wherein the exposure control index is N slit or radiation dose.

6. A control unit comprising means for setting a position of a shielding plate arranged in a shielding device, wherein the control unit is operable to perform the method for controlling the exposure dose according to any one of claims 1 to 5.

7. A control unit according to claim 6, further comprising means for setting and adjusting the radiation characteristics of the radiation source used during exposure of the substrate.

8. A shielding device for selectively shielding portions of a patterning device from a radiation beam, comprising: a plurality of shielding plates, each shielding plate being mechanically separate from one another; as well as a control unit arranged to control a position of each of the plurality of shielding plates; Wherein the position of at least two of the plurality of shielding plates is defined by a velocity profile of a substrate support, the velocity profile being provided to the control unit.

9. A screening arrangement according to claim 8, wherein the speed profile comprises a non-constant speed.

10. A screening arrangement according to claim 8 or 9, wherein the speed profile comprises a sinusoidal speed profile.

11. An illumination system comprising the shading device according to any one of claims 8 to 10.

12. An exposure apparatus comprising the illumination system according to claim 11.

13. A method for controlling a position of a shielding plate of a shielding arrangement, comprising: receiving a first input at a control unit, said first input comprising information of a velocity profile of a mask support and / or a substrate support to be used during exposure of the substrate; receiving a second input at the control unit, the second input being an exposure control indicator; determining a position set point for the mask during exposure; as well as The shielding plate is moved to the determined position set point.

14. The method according to claim 13, wherein the exposure control index is N slit or radiation dose.

15. The method according to claim 13 or 14, further comprising receiving a shutter position signal at the control unit, the shutter position signal being used as a feedforward signal or a feedback signal.

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