End effector, lithographic apparatus and method for handling a substrate - Patents.com

Abstract

Disclosed is an end effector for handling a substrate, the end effector comprising: a base; a clamp body with an actuator configured to switch between a first position in which the substrate is fixed in a fixed position relative to the clamp body and a second position in which the substrate is released; a guide mechanism that connects the clamp body to the base while allowing the clamp body to move freely relative to the base within a predetermined movable range; and a fixing mechanism that switches the connection between the clamp body and the base between a fixed position in which the clamp body is fixed to the base and a free position in which the clamp body can move relative to the base.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Application No. 22165835.4, filed March 31, 2022, which is incorporated by reference in its entirety.

[0002] The present invention relates to an end effector and a method for handling a substrate, the substrate may be, for example, a wafer, a mask or a reticle, the substrate may be for use in a lithographic apparatus and / or a lithographic process. [Background technology]

[0003] A lithographic apparatus is a machine built to apply a desired pattern onto a substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus can, for example, project a pattern (often also called a "design layout" or "design") in a patterning device (e.g., mask) onto a layer of radiation-sensitive material (resist) provided on a substrate (e.g., wafer).

[0004] As semiconductor manufacturing processes continue to advance, following a trend commonly referred to as "Moore's Law", the dimensions of circuit elements are continually shrinking and the amount of functional elements, such as transistors, per device has been steadily increasing for decades. To keep up with Moore's Law, the semiconductor industry is seeking technologies that allow it to create smaller and smaller features. To project a pattern onto a substrate, lithography equipment can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features that can be patterned on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. Lithography equipment using extreme ultraviolet (EUV) radiation, with wavelengths in the range of 4 nm to 20 nm, e.g., 6.7 nm or 13.5 nm, can be used to form smaller features on a substrate than lithography equipment using radiation with a wavelength of, e.g., 193 nm.

[0005] There are a variety of end effectors for handling the wafer, including those that clamp the underside of the wafer by vacuum, gravity, or electrostatic interaction.

[0006] KR100777201B1 discloses an end effector having grippers (30, 40) on two different structures (10, 20) that are movable relative to each other, for example by pneumatic pressure, to control the gripping movement.

[0007] US20090175705A1 describes a substrate transport device capable of supporting a wafer from above. The gripping mechanism has a fixed support part (28a) and a movable support part (28b) that can be controlled by air pressure.

[0008] The prior art end effectors discussed above have a fixed position relative to the robot that manipulates them. As a result, very precise positioning of the end effector with respect to the wafer is required. If precise alignment is not achieved, the wafer may be pushed against the edge of the gripper and damaged. Adding actuators improves positioning accuracy but adds cost, volume, and complexity. Also, heat dissipation from the actuators may reduce the accuracy of subsequent wafer processing.

[0009] SUMMARY OF THE DISCLOSURE The present disclosure aims to provide an improved end effector that avoids one or more of the shortcomings of prior art end effectors. Summary of the Invention

[0010] The present disclosure provides an end effector for handling a substrate, comprising: With the base, a clamp body including an actuator configured to switch between a first position in which the substrate is secured in place relative to the clamp body and a second position in which the substrate is released; a guide mechanism that connects the clamp body to the base while allowing the clamp body to move freely relative to the base within a predetermined movable range; An end effector is provided that includes a fixing mechanism that switches the connection between the clamp body and the base between a fixed position where the clamp body is fixed to the base and a free position where the clamp body is movable relative to the base.

[0011] In one embodiment, the clamp body comprises at least one fixed finger and at least one actuating finger comprising an actuator, and in a first position the substrate is fixed in position between an end of the at least one fixed finger and an end of the actuator of the at least one actuating finger.

[0012] In one embodiment, the guide mechanism includes at least one spring element, each spring element having one end connected to the base and an opposite end connected to the clamp body.

[0013] In one embodiment, the at least one spring element comprises a leaf spring or a bent piece of flexible material such as spring steel or a similar material.

[0014] In one embodiment, an end of at least one spring element is connected to the base and the clamp body by one or more of an adhesive, a weld, or a soldering.

[0015] In one embodiment, at least one spring element has a shape that allows relative movement between its ends in the horizontal plane (x, y) while preventing or at least limiting movement in the vertical direction (z).

[0016] In one embodiment, the predetermined range of motion permitted by the guide mechanism includes a lateral movement in the horizontal plane of ±500 μm, such as about ±250 μm, for example about ±200 μm, for example about ±150 μm, for example about ±100 μm, such as about ±50 μm, for example about ±20 μm, for example about ±10 μm.

[0017] In one embodiment, the predetermined range of motion permitted by the guiding mechanism includes a rotation θ, where θ is in the range of ±5 degrees, such as ±4 degrees, for example ±3 degrees, such as ±2 degrees, for example ±1 degree, for example ±0.5 degrees, such as ±0.4 degrees, for example ±0.3 degrees, such as ±0.2 degrees, for example ±0.1 degrees.

[0018] In one embodiment, the guide mechanism is adapted to move the clamp body to a reference position relative to the base when the locking mechanism is in the free position.

[0019] In one embodiment, the securing mechanism comprises at least one vacuum line. The at least one vacuum line may control an actuator. The at least one vacuum line may control the securing mechanism. The at least one vacuum line may comprise a first section included in the base, the first section connected to a vacuum bridge, the vacuum bridge having one or more openings connecting the first section in the base to a corresponding section of the vacuum line in the clamp body, the section of the vacuum line in the clamp body may be connected to the actuator.

[0020] In one embodiment, the section of the vacuum line within the clamp body includes a check valve and / or a flow restrictor.

[0021] In one embodiment, the actuator comprises a spring for preloading the grippers, urging them outward in a position that allows engagement with the edge of the substrate.

[0022] According to another aspect, the present disclosure provides a lithographic apparatus comprising an end effector as described above.

[0023] According to yet another aspect, the present disclosure provides a method of using an end effector to handle a substrate, the method comprising: The end effector is With the base, a clamp body including an actuator configured to switch between a first position in which the substrate is secured in place relative to the clamp body and a second position in which the substrate is released; a guide mechanism that connects the clamp body to the base while allowing the clamp body to move freely relative to the base within a predetermined movable range; a fixing mechanism that switches a connection between the clamp body and the base between a fixed position where the clamp body is fixed to the base and a free position where the clamp body is movable relative to the base; The method is: moving the clamp body laterally over the substrate; lowering the clamp body onto the substrate; switching the locking mechanism to a free position; switching the actuator to a first position; switching the locking mechanism to a locking position; Lifting the clamp body and the substrate and moving the clamp body to another location; switching the actuator to a second position; and lifting the clamp body without the substrate.

[0024] In one embodiment, the step of switching the locking mechanism to the locking position comprises increasing the pressure in the first vacuum line to a first threshold P thr1 This includes reducing the

[0025] In one embodiment, the step of switching the locking mechanism to the free position comprises increasing the pressure in the first vacuum line to a second threshold P thr2 This includes increasing the

[0026] In one embodiment, the step of switching the actuator to the second position includes increasing the pressure in the second vacuum line to a third threshold P thr3 The step of reducing the pressure in the second vacuum line below a fourth threshold P thr4 This includes increasing the

[0027] In an embodiment, the method comprises projecting a patterned beam of radiation onto a substrate. [Brief description of the drawings]

[0028] [Figure 1] 1 depicts a schematic diagram of a lithographic apparatus; [Diagram 2] FIG. 1 is a schematic side view of one embodiment of an end effector of the present disclosure. [Figure 3A] FIG. 3 is a schematic top view of the end effector of FIG. 2 taken along line III-III. [Figure 3B] FIG. 2 is a schematic perspective view of an end effector according to one embodiment. [Figure 3C] FIG. 13 is a schematic perspective view of an end effector according to another embodiment. [Figure 4] FIG. 13 is a schematic side view of another embodiment of an end effector of the present disclosure. [Diagram 5] 1 is a schematic side view of an embodiment of an end effector at a step of a method of an embodiment of the present disclosure. FIG. [Figure 6] 1 is a schematic side view of an embodiment of an end effector at a step of a method of an embodiment of the present disclosure. FIG. [Figure 7] 1 is a schematic side view of an embodiment of an end effector at a step of a method of an embodiment of the present disclosure. FIG. [Figure 8] 1 is a schematic side view of an embodiment of an end effector at a step of a method of an embodiment of the present disclosure. FIG. [Figure 9] 1 is a schematic side view of an embodiment of an end effector at a step of a method of an embodiment of the present disclosure. FIG. [Figure 10] 1 is a schematic side view of an embodiment of an end effector at a step of a method of an embodiment of the present disclosure. FIG. [Figure 11] 1 is a schematic side view of an embodiment of an end effector at a step of a method of an embodiment of the present disclosure. FIG. [Figure 12] 1 is a schematic side view of an embodiment of an end effector at a step of a method of an embodiment of the present disclosure. FIG. [Figure 13] 1 is an exemplary diagram of pressure P (vertical axis) versus time (horizontal axis) in a vacuum line that can switch an end effector of the present disclosure between various positions. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] In this document, the terms "radiation" and "beam" are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g., having a wavelength of 365, 248, 193, 157, or 126 nm) and EUV (extreme ultraviolet radiation, e.g., having a wavelength in the range of about 5 to 100 nm).

[0030] The terms "reticle," "mask" or "patterning device" as used herein may be broadly interpreted to refer to any general patterning device that can be used to impart an incident radiation beam with a patterned cross-section that corresponds to the pattern to be created in a target portion of a substrate. The term "light valve" may also be used in this context. In addition to traditional masks (transmissive or reflective; binary, phase-shifting, hybrid, etc.), examples of other such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0031] Fig. 1 shows a schematic diagram of a lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system (also called illuminator) IL configured to condition a radiation beam B (e.g. UV radiation, DUV radiation or EUV radiation), a mask support (e.g. mask table) MT constructed to support a patterning device (e.g. mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA according to certain parameters, a substrate support (e.g. wafer table) WT constructed to hold a substrate (e.g. resist-covered wafer) W and connected to a second positioner PW configured to accurately position the substrate support according to certain parameters, and a projection system (e.g. refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C of the substrate W (e.g. comprising one or more dies).

[0032] In operation, the illumination system IL receives a radiation beam from the radiation source SO, for example via the beam delivery system BD. 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, to direct, shape and / or control the radiation. The illuminator IL may be used to condition the radiation beam B such that it has a desired spatial and angular intensity distribution in its cross-section in the plane of the patterning device MA.

[0033] The term "projection system" PS as used herein should be interpreted broadly to encompass various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and / or electrostatic optical systems, or any combination thereof, appropriate for the exposure radiation used and / or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein can be considered as synonymous with the more general term "projection system" PS.

[0034] The lithographic apparatus LA may be of a type in which at least a part of the substrate may be covered by a liquid having a relatively high refractive index, such as water, so as to fill a space between the projection system PS and the substrate W, which is also referred to as immersion lithography. Details of immersion techniques are described in US6952253, which is incorporated herein by reference.

[0035] The lithographic apparatus LA may be of a type that has two or more substrate supports WT (also referred to as "dual stage"). In such a "multiple stage" machine, the substrate supports WT can be used in parallel and / or can be used to perform preparatory steps for a subsequent exposure on a substrate W arranged on one of the substrate supports WT, while simultaneously exposing a pattern on another substrate W on the other substrate support WT.

[0036] In addition to the substrate support WT, the lithographic apparatus LA may comprise a measurement stage. The measurement stage is configured to hold a sensor and / or a cleaning device. The sensor is configured to measure a property of the projection system PS or a property of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning device is configured to clean a part of the lithographic apparatus, for example a part of the projection system PS or a part of a system for providing immersion liquid. The measurement stage may be moved below the projection system PS when the substrate support WT is spaced apart from the projection system PS.

[0037] In operation, the radiation beam B is incident on a patterning device MA, e.g. a mask, held on a mask support MT and is patterned by a pattern (design layout) present on the patterning device MA. After passing through the mask MA, the radiation beam B passes through a projection system PS which focuses the beam onto a target portion C of a substrate W. With the aid of a second positioner PW and a position measurement system PMS, the substrate support WT can be precisely moved, e.g. to position various target portions C in the path of the radiation beam B in a focused and aligned position. Similarly, the first positioner PM and possibly further position sensors (not explicitly shown in FIG. 1 ) can be used to precisely position the patterning device MA with respect to the path of the radiation beam B. The patterning device MA and substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. As shown the substrate alignment marks P1, P2 occupy dedicated target portions, although they may be located in spaces between the target portions. When the substrate alignment marks P1, P2 are located between target portions C, they are known as scribe-lane alignment marks.

[0038] For clarity of the invention, a Cartesian coordinate system is used. There are three axes in the Cartesian coordinate system: X, Y, and Z. Each of the three axes is orthogonal to the other two. Rotation about the X axis is called Rx rotation. Rotation about the Y axis is called Ry rotation. Rotation about the Z axis is called Rz rotation. The X and Y axes define the horizontal plane, and the Z axis defines the vertical direction. The Cartesian coordinate system is not a limitation of the invention and is used for illustration purposes only. Alternatively, another coordinate system, such as a cylindrical coordinate system, can be used to clarify the invention. The orientation of the Cartesian coordinate system may be different, for example, such that the Z axis has a component along the horizontal plane.

[0039] Generally, referring to Figures 2 to 4, a new end effector EE is provided. The end effector may comprise a base BA. The base BA may be fixed to or fixedly attached to the robot RO. The end effector EE may comprise a clamping body CB. The body CB may be a "floating" clamping body that is free from the robot RO. Free in this context means, for example, that the clamping body CB can move within a certain range relative to the base and / or the robot.

[0040] The clamp body may comprise one or more, typically a large number of, fingers FI for holding and releasing the substrate SUB. The substrate may be, for example, a wafer W, a reticle or a mask MA. At least one finger 20 of the one or more fingers FI may be fixed. The one or more fixed fingers 20 have an end that aligns with the edge of the substrate SUB (left side in FIG. 2). At least one other finger may be an actuating finger 22 that is movable relative to the clamp body CB or has a movable part. The actuating finger 22 allows to hold the substrate SUB in place, for example by clamping the substrate between the ends of the respective fingers, and to subsequently release the substrate. The end effector EE may, for example, move the substrate SUB between one position and another. For example, the end effector may move the substrate from another position to a chuck or similar holding structure CH, typically provided on top of a wafer table WT (see FIG. 1), and subsequently remove the substrate from the chuck. The separate location may be, but is not limited to, another wafer table, a storage facility, or a container for holding wafers between respective lithography steps.

[0041] The base BA may be reversibly securable to the clamp body CB via an interface 30. The interface may be pneumatic, but is not limited to such. The interface 30 may be, for example, mechanical or electromagnetic. When the clamp body CB is secured to the base BA, the end effector is configured (e.g., by being connected to a handler robot) to align the fixed fingers 20 of the clamp body with the wafer, thereby avoiding possible damage to the wafer.

[0042] The interface 30 creates an actuation mechanism between the base BA and the clamp body CB. The actuation mechanism is configured to actuate at least one actuation finger 22 of the clamp body to enable clamping and releasing of the substrate SUB. The end effector may include a guide mechanism 40 that provides freedom of movement of the clamp body CB relative to the base BA within a predetermined range.

[0043] The guiding mechanism may, for example, include one or more springs or spring elements 42, 44, 46 connecting the clamp body to the base BA. The spring elements 42-46 may, for example, be leaf springs and / or may include bent pieces of flexible material such as spring steel or a similar material. Both ends of the spring elements are connected to the base and the clamp body, respectively. The ends of the spring elements may, for example, be connected to the base and the clamp body, respectively, by adhesive, welding or soldering. The spring elements 42-46 may have a shape that allows relative movement between their ends in a horizontal plane (x, y) while preventing or at least limiting movement in a vertical direction (z). The guiding mechanism 40 may, for example, allow the clamp body to move with up to three degrees of freedom relative to the base BA and / or the robot RO. The degrees of freedom may, for example, include lateral movement in a horizontal plane (t x ,t y ) and rotation in the horizontal plane (r z ) may be included.

[0044] The movement of the clamp body relative to the base BA allows it to adapt to the position of the substrate SUB in addition to the positioning controlled by the robot RO. Indeed, during the lithography process, the substrate may be positioned slightly offset (eccentric) from the center of the chuck CH. Although the lithography process itself can adapt to this eccentricity within a certain range, it is important to maintain the same relative eccentricity for the same wafer for subsequent steps in the lithography process. After all, at each step of the process, the lithography apparatus may need to identify markers (see FIG. 1, e.g. markers P1, P2 of the wafer W and e.g. markers M1, M2 of the mask MA) before illumination in order to allow the required accuracy for processing the respective layer on the wafer. To maintain a throughput above a threshold suitable for commercial applications, it is important that the apparatus LA is able to identify the position of the markers within a given time that is fast enough. By maintaining the same relative position of the substrate relative to the chuck between each lithography step, the markers also maintain the same relative position, making it easier for the apparatus LA to identify their position. The guide mechanism 40 provides an additional means for accurately positioning the clamp body relative to the substrate in addition to the movements controlled by the robot RO. In effect, the guide mechanism provides a means for improving the level of accuracy of the clamp body movements over that of the robot. Here, the disclosed method and system avoids bulky add-ons and actuators, allowing the use of a relatively simple and modestly priced robot RO, while still providing relatively good accuracy. After clamping the clamp body to the substrate, the position of the clamp body and the clamped substrate can be fixed relative to the base BA, and the precise position of the substrate can be maintained between each position and each step of the lithography process.

[0045] In practical embodiments, the predetermined range of motion permitted by the guide mechanism 40 may be, for example, about ±5 mm, about ±4 mm, about ±3 mm, about ±2.5 mm, about ±2 mm, about ±1.5 mm, about ±1 mm, about ±500 μm, about ±250 μm, about ±200 μm, about ±150 μm, about ±100 μm, about ±50 μm, about ±20 μm, about ±10 μm for lateral movement in the horizontal plane (translation in the x and / or y directions, see FIG. 2).

[0046] One may wish to express the rotation r permitted by the guiding mechanism as a rotational vector, or Euler vector, i.e., an unnormalized three-dimensional vector, r = θe, where the direction of the axis of rotation is e = [e x ,e y ,e z In a practical embodiment, the guide mechanism is determined by e z >>e x ,e y As a result, r is z , i.e., a rotation about a vertical axis. The length of the rotation vector r is determined by the rotation angle θ. In practical embodiments, the guiding mechanism 40 may allow for θ within a range of about ±1 degree, about ±2 degrees, about ±3 degrees, about ±4 degrees, about ±5 degrees, about ±6 degrees, about ±7 degrees, about ±8 degrees, about ±9 degrees, about ±10 degrees, or more.

[0047] The end effector may include a compliance mechanism. The compliance mechanism has a function of moving the clamp body CB to a reference position relative to the base BA. In the above-mentioned embodiment, the guide mechanism includes the spring elements 42, 44, 46. Here, the spring elements function as the compliance mechanism. Thus, for example, the compliance mechanism and the guide mechanism can be integrated, i.e., the spring elements function as both the compliance mechanism and the guide mechanism.

[0048] The end effector EE may include a locking mechanism 50. The locking mechanism may be incorporated into the interface 30. The locking mechanism is adapted to allow the clamp body CB to switch between a free or movable position, in which the clamp body CB can move within a range relative to the base BA, and a fixed position, in which the clamp body CB is fixed relative to the base BA. The locking mechanism may also allow the clamp body to have the freedom of clamping, i.e., to control the actuator 74.

[0049] In one embodiment, the end effector EE may comprise one or more vacuum lines, for example for controlling the securing mechanism 50 and / or the actuator 74. The at least one vacuum line may comprise a first vacuum line 52 and / or a second vacuum line 53. The second vacuum line is described in more detail below with respect to FIG. 4. The first vacuum line 52 may comprise a first section 54 contained in a base BA. As shown in FIG. 3A, the base itself may have a fork structure with a number of, for example, two fingers 60, 62. The first section 54 may be divided into two second sections 56, 58, which may be respectively contained in the fingers 60, 62 of the base. The second sections 56, 58 of the vacuum line may be connected to a vacuum bridge or vacuum connector 64. The vacuum connector is included in the interface 30. The vacuum bridge may have one or more openings 66, 68, 70 that allow the connection of one or more sections 56, 58 of the vacuum line in the base BA to a corresponding section 72 of the vacuum line in the clamp body CB. One or more of the openings 66, 68, 70 may be provided with suitable vacuum seals or gaskets 67, 69, 71. Said seals may be O-rings made of a suitable material. The material may be rubber or special polymers suitable as seals for (high) vacuum environments.

[0050] The pressure in line 52 can control whether the clamp body is free to move relative to the base BA or is fixed to the base. The pressure in line 52 can be controlled using a suitable pump and controller (not shown) that can be included in or connected to the robot RO. With general reference to FIG. 13, by way of example, the pressure in line 52 can be adjusted to a predetermined first threshold P thr1 When the pressure in line 52 falls below a predetermined second threshold P thr2 When the clamp body is released from the base and is free to move relative to the base as described herein, the first and second pressure thresholds may be substantially the same or may be slightly different.

[0051] A vacuum line 72 in the body may connect the opening 68 in the vacuum bridge to an actuator 74 via an opening 76. The actuator 74 may be a pneumatic actuator. The actuator 74 may be movable between a first position, e.g., an open position, in which the actuator is disengaged from the substrate SUB, and a second position, e.g., a closed position, in which an edge or gripper 78 (see FIG. 2) of the actuator engages a side of the substrate.

[0052] In a practical embodiment, the actuator may comprise a spring 79. The spring 79 may preload the gripper 78 and push it outward to a position that allows engagement with the edge of the substrate. The spring 79 has a certain spring constant k. The formula for the spring force is expressed by the equation F=-kx, where F is the applied force, k is the spring constant and represents how proportionally stiff or strong the spring is, and x is the distance the spring is stretched or compressed from its equilibrium or rest position. The unit of force may be Newtons per meter (N / m). The minus sign indicates that this force is in the opposite direction to the force that stretches or compresses the spring. The spring may have a spring force in the opposite direction to the compression direction. When the pressure in the line 72 is reduced, the end 78 of the actuator 74 is pulled inward, compressing the spring 79.

[0053] As a practical example, and referring generally to FIG. 13, when the pressure falls below a certain value, e.g., a third threshold P thr3 Below the third threshold P the gripper 78 can release the edge of the substrate. thr3 may be between pressures P2 and P3 (described in more detail herein below).

[0054] The body vacuum line 72 may be provided with a valve 80 and / or a flow restrictor 82. The valve and flow restrictor may permit or enable two levels of pressure switching for separate operations, such as securing the clamp body CB to the base BA (via the interface 30) and clamping or releasing the substrate (via the actuator 74).

[0055] The valve 80 may be a check valve. A check valve may also be called a non-return valve, reflux valve, retention valve, foot valve, or one-way valve. A check valve is a valve that typically allows a fluid (liquid or gas) to flow only in one direction. In the embodiment of FIG. 2, the check valve 80 may allow flow from the actuator 74 to the base BA. This allows a vacuum to be applied in the line 52 to remove gas from the actuator. The vacuum may be continuously applied using a pump connected upstream of the line 52. In practice, the actuator 74 will usually always leak at least a little, for example through the sides of the edge of the gripper 78. The latter typically allows the valve 80 to be deactivated, including a delay depending on the rate of gas leakage. The valve 80 may be deactivated, for example, by terminating the vacuum actively applied via the vacuum lines 72, 52. 13, applying a pressure of the order of P2 to lines 52, 72 allows actuator 74 to be deactivated while retaining clamping mechanism 50 in interface 30 activated, i.e. in a fixed position. It is also possible to deactivate clamping mechanism 50 while actuator 74 remains activated (for a time depending on the rate of gas leakage in the actuator) to clamp and hold the substrate. The latter can be done, for example, by switching the gas supply to near a reference pressure (e.g., a pressure of about 1 atmosphere or P3 in line 52 as shown in FIG. 13), while a throttle device 82 slows down the change in pressure upstream of valve 80.

[0056] 4 shows an alternative embodiment of the end effector EE. Instead of the valve 80 and the throttle device 82, the base BA may be provided with two or more pneumatic or vacuum lines 52, 53. Here, the line 52 may be connected to the actuator 74 via a section 72 of a corresponding vacuum line in the clamp body, as described above. A second pneumatic or vacuum line 53 is connected to and can control the fixing mechanism 50. Here, the vacuum in the line 53 can lock or fix the clamp body relative to the base. A higher pressure in the line 53, for example atmospheric pressure, can move the body CB relative to the base, within the constraints set by the guiding mechanism 40.

[0057] Fig. 3C shows another embodiment, where the vacuum lines are provided as tubes 52a, 53a. Here, the first tube 53a connects a first vacuum device, such as a pump in or connected to the robot RO, to the actuator 74. The second tube 52a connects a second vacuum device in or connected to the robot RO to the fixation device 50. The first tube 53a and / or the second tube 52a may be flexible tubes made of a flexible material, such as rubber or an elastomer, such as PTFE (polytetrafluoroethylene).

[0058] Exemplary steps of a method of operating an end effector of the present disclosure are described herein below with general reference to FIGS.

[0059] Figure 13 shows an example of the pressure level in at least one vacuum line 52 during the operation of the end effector EE. In Figure 13, the pressure P in line 52 is shown on the vertical axis, and values in the range from the reference level shown as "0" to the reduced pressure level or vacuum are shown. Figure 13 shows, as an example, three respective pressure levels P1, P2, and P3. In a practical embodiment, the reference level 0 can be about atmospheric pressure or 1 bar. The pressure levels P1, P2, P3 can be in the range of about 0 to 200 kPa lower than the reference level. The reference level may be about 1 bar, or 1 atmosphere. Here, P1 < P2 < P3. For example, P3 may be about the reference level, or about 0 to 5 kPa subtracted from the reference level. P2 may be a value about 10 kPa to 50 kPa, for example about 25 kPa lower than the reference level. P1 may be a value about 30 kPa to 100 kPa, for example about 50 kPa lower than the reference level.

[0060] Alternative options are also possible, such as using two or more separate pressure control lines 52a, 53a (Figure 3C) or 52, 53 (Figure 4). An additional check valve 82 may be added to create additional pressure control levels. In Figure 13, the time t is shown on the horizontal axis. The upper two lines of the graph show the position of the actuator 74 on the actuating finger 22 (first line) and the position of the clamp body CB (second line). Here, the actuator 74 is in the open position ACT op (where the substrate is released) and the closed position ACT cl (where the actuator can engage the side or edge of the substrate) and can move between them. The clamp body is in the fixed position CB fix (where the clamp body is fixed to the base) and the free position CB fr (where the clamp body can move relative to the base) and can move between them.

[0061] The figures show the operation of the end effector to lift the substrate from the chuck and move the substrate to another location, however, similar steps allow the end effector to move the substrate from another location to the chuck or to any other location.

[0062] In the first step shown in Figure 5, the robot RO moves its end effector towards the substrate and positions the clamp body above the substrate. The positioning accuracy here is determined by the best accuracy the robot can achieve. The actuator 74 is in the open position and the clamp body is in a fixed position.

[0063] In a second step, shown in Fig. 6, the robot lowers the base and the attached clamp body onto the substrate. The ends of each finger FI are level with the edge of the substrate SUB. Alternatively or additionally, the chuck CH can raise the substrate SUB towards the clamp body CB.

[0064] In a third step, shown in Fig. 7, the clamp body is switched to a free position. Here, the clamp body is released from the base, which may create a space or opening 90 between the base and the clamp body. Here, the guide mechanism 40 guides and limits the freedom of movement of the clamp body CB relative to the base BA. The release of the clamp body may be achieved, for example, by increasing the pressure in the control line 52 to a pressure level P3. P3 may be at or near a reference level or atmospheric pressure, as described above.

[0065] In the fourth step shown in Fig. 8, the actuator 74 switches to the closed position. Here, the gripper part 78 of the actuator 74 engages the side or edge of the substrate, clamping it between the gripper 78 and the end of the other respective finger FI. Although shown in different figures, the third and fourth steps may be controlled or initiated by the same pressure, namely by the rise of the pressure P in the line 52 to P3. Due to timing differences, for example due to the flow restrictor 82 in the line 72, the actuator 74 may in fact be actuated slightly later than the moment when the clamp body is released from the base. With reference to Fig. 13, the dotted lines show possible variations in the pressure level in the actuator relative to the pressure level in the line 52.

[0066] In the fifth step shown in Figure 9, the position of the clamp body CB is again fixed relative to the base. This step ensures that the substrate remains in the same position relative to the chuck during transfer to another location. As explained above, maintaining the position of the substrate allows the lithography process to maintain a high throughput rate even if the substrate is slightly misaligned relative to the nominal position.

[0067] In a sixth step, shown in Figure 10, the substrate is released from its position, for example on the chuck CH. The robot RO lifts the base together with the clamp body CB and the substrate.

[0068] In the seventh step, shown in Figure 11, the robot places the substrate at another selected location. The substrate is lowered. The actuator 74 is moved to the open position, clearing the gripper 78 from the edge of the substrate.

[0069] In an eighth step, shown in FIG. 12, the robot RO lifts the clamp body CB, leaving the substrate in the selected position 92.

[0070] Although specific reference may be made herein to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, including 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, etc.

[0071] Although specific reference may be made herein to embodiments of the invention in the context of a lithographic apparatus, embodiments of the invention may be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatus may be generally referred to as lithography tools. Such lithography tools may use vacuum or ambient (non-vacuum) conditions.

[0072] Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be understood that, where the context permits, the invention is not limited to optical lithography and may be used in other applications such as, for example, imprint lithography.

[0073] Where the context permits, 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 as instructions stored on a machine-readable medium that may 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.), among others. Furthermore, firmware, software, routines, instructions may be described herein as performing certain operations. However, it should be understood that such description is merely for convenience and that such operations may in fact result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., which may cause actuators or other devices to interact with the physical world.

[0074] While specific embodiments of the invention have been described above, it should be understood that the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not limiting. Thus, it will be apparent to one skilled in the art that modifications can be made to the invention as described without departing from the scope of the claims set forth below. Other aspects of the invention are described in the following numbered passages. 1. An end effector for handling a substrate, comprising: With the base, a clamp body including an actuator configured to switch between a first position in which the substrate is secured in place relative to the clamp body and a second position in which the substrate is released; a guide mechanism that connects the clamp body to the base while allowing the clamp body to move freely relative to the base within a predetermined movable range; An end effector comprising a fixing mechanism that switches the connection between the clamp body and the base between a fixed position in which the clamp body is fixed relative to the base and a free position in which the clamp body is movable relative to the base. 2. The end effector described in clause 1, wherein the clamp body comprises at least one fixed finger and at least one actuating finger comprising the actuator, and in the first position the substrate is fixed in a fixed position between an end of the at least one fixed finger and an end of the actuator of the at least one actuating finger. 3. The end effector of clause 1 or 2, wherein the guiding mechanism includes at least one spring element, each spring element having one end connected to the base and an opposite end connected to the clamp body. 4. The end effector of clause 3, wherein the at least one spring element comprises a leaf spring or a bent piece of flexible material such as spring steel or a similar material. 5. The end effector of claim 3 or 4, wherein an end of the at least one spring element is connected to the base and the clamp body by one or more of an adhesive, welding, or soldering. 6. An end effector described in any of clauses 3 to 5, wherein the at least one spring element has a shape that allows relative movement between its ends in a horizontal plane (x, y) while preventing or at least limiting movement in a vertical direction (z). 7. An end effector described in any of clauses 1 to 6, wherein the predetermined range of motion permitted by the guiding mechanism includes a lateral movement in the horizontal plane of ±5 mm, for example about ±4 mm, for example about ±3 mm, for example about ±2.5 mm, for example about ±2 mm, for example about ±1.5 mm, for example about ±1 mm, for example about ±500 μm, for example about ±250 μm, for example about ±200 μm, for example about ±150 μm, for example about ±100 μm, for example about ±50 μm, for example about ±20 μm, for example about ±10 μm. 8. An end effector described in any of clauses 1 to 7, wherein the predetermined range of motion permitted by the guiding mechanism includes a rotation θ, where θ is in the range of ±5 degrees, for example ±4 degrees, for example ±3 degrees, for example ±2 degrees, for example ±1 degree, for example ±0.5 degrees, for example ±0.4 degrees, for example ±0.3 degrees, for example ±0.2 degrees, for example ±0.1 degrees. 9. The end effector of any of clauses 1 to 8, wherein the guide mechanism is adapted to move the clamp body to a reference position relative to the base when the fixing mechanism is in the free position. 10. The end effector of any of clauses 1 to 9, wherein the fixing mechanism is connected to at least one vacuum line for controlling the fixing mechanism. 11. The end effector of clause 10, wherein the at least one vacuum line comprises a first section contained in the base, the first section connected to a vacuum bridge, the vacuum bridge having one or more openings connecting the first section in the base to a corresponding section of a vacuum line in the clamp body, the section of the vacuum line in the clamp body connected to the actuator. 12. The end effector of clause 11, wherein the section of the vacuum line within the clamp body includes a check valve and / or a flow restrictor. 13. An end effector according to any of clauses 1 to 12, wherein the actuator comprises a spring for preloading the gripper, the spring urging the gripper outward in a position that allows engagement with the edge of the substrate. 14. A lithographic apparatus comprising an end effector according to any one of clauses 1 to 13. 15. A method of using an end effector to handle a substrate, comprising: The end effector includes: With the base, a clamp body including an actuator configured to switch between a first position in which the substrate is secured in place relative to the clamp body and a second position in which the substrate is released; a guide mechanism that connects the clamp body to the base while allowing the clamp body to move freely relative to the base within a predetermined movable range; a fixing mechanism that switches a connection between the clamp body and the base between a fixed position in which the clamp body is fixed to the base and a free position in which the clamp body is movable relative to the base; The method comprises: moving the clamp body laterally over the substrate; lowering the clamp body onto the substrate; switching the locking mechanism to the free position; switching the actuator to the first position; switching the locking mechanism to the locking position; lifting the clamp body and the substrate and moving the clamp body to another location; switching the actuator to the second position; and lifting the clamp body without the substrate. 16. The step of switching the locking mechanism to the locking position includes reducing the pressure in the first vacuum line to a first threshold P thr1 16. The method of claim 15, comprising reducing the 17. The step of switching the locking mechanism to the free position includes reducing the pressure in the first vacuum line to a second threshold P thr2 17. The method of claim 15 or 16, comprising increasing the expression level of 18. The step of switching the actuator to the second position includes reducing the pressure in the second vacuum line to a third threshold P thr3 and / or switching the actuator to the first position reduces the pressure in the second vacuum line below a fourth threshold P thr4 18. The method of any of clauses 15 to 17, comprising increasing the concentration of 19. The method of any of clauses 15 to 18, comprising projecting a patterned beam of radiation onto a substrate.

Claims

1. 1. An end effector for handling a substrate, comprising: With the base, a clamp body including an actuator configured to switch between a first position in which the substrate is secured in place relative to the clamp body and a second position in which the substrate is released; a guide mechanism that connects the clamp body to the base while allowing the clamp body to move freely relative to the base within a predetermined movable range; An end effector comprising a fixing mechanism that switches the connection between the clamp body and the base between a fixed position in which the clamp body is fixed relative to the base and a free position in which the clamp body is movable relative to the base.

2. 2. The end effector of claim 1, wherein the clamp body comprises at least one fixed finger and at least one actuating finger comprising the actuator, and in the first position the substrate is fixed in a fixed position between an end of the at least one fixed finger and an end of the actuator of the at least one actuating finger.

3. The end effector of claim 1 or 2, wherein the guide mechanism comprises at least one spring element, each spring element having one end connected to the base and an opposite end connected to the clamp body.

4. The end effector of claim 3 , wherein the at least one spring element comprises a leaf spring or a bent piece of flexible material such as spring steel or a similar material.

5. The end effector of claim 3 or 4, wherein an end of the at least one spring element is connected to the base and the clamp body by one or more of an adhesive, a welding, or a soldering.

6. 6. An end effector according to claim 3, wherein the at least one spring element has a shape that allows relative movement between its ends in a horizontal plane (x, y) while preventing or at least limiting movement in a vertical direction (z).

7. 7. An end effector according to any preceding claim, wherein the predetermined range of motion permitted by the guiding mechanism comprises a lateral movement in a horizontal plane of ±5 mm, such as about ±4 mm, for example about ±3 mm, such as about ±2.5 mm, for example about ±2 mm, such as about ±1.5 mm, for example about ±1 mm, such as about ±500 μm, for example about ±250 μm, for example about ±200 μm, such as about ±150 μm, for example about ±100 μm, such as about ±50 μm, for example about ±20 μm, for example about ±10 μm.

8. 8. An end effector according to any preceding claim, wherein the predetermined range of motion permitted by the guiding mechanism includes a rotation θ, where θ is in the range of ±5 degrees, for example ±4 degrees, for example ±3 degrees, for example ±2 degrees, for example ±1 degree, for example ±0.5 degrees, for example ±0.4 degrees, for example ±0.3 degrees, for example ±0.2 degrees, for example ±0.1 degrees.

9. The end effector of claim 1 , wherein the guide mechanism is adapted to move the clamp body to a reference position relative to the base when the locking mechanism is in the free position.

10. The end effector of claim 1 , wherein the clamping mechanism is connected to at least one vacuum line for controlling the clamping mechanism.

11. 11. The end effector of claim 10, wherein the at least one vacuum line comprises a first section included in the base, the first section connected to a vacuum bridge, the vacuum bridge having one or more openings connecting the first section in the base to a corresponding section of a vacuum line in the clamp body, the section of the vacuum line in the clamp body connected to the actuator.

12. The end effector of claim 11 , wherein the section of the vacuum line within the clamp body comprises a check valve and / or a flow restrictor.

13. The end effector of claim 1 , wherein the actuator comprises a spring for preloading a gripper, the spring urging the gripper outwardly in a position that allows engagement with an edge of the substrate.

14. A lithographic apparatus comprising an end effector according to any one of claims 1 to 13.

15. 1. A method of using an end effector to handle a substrate, comprising: The end effector includes: With the base, a clamp body including an actuator configured to switch between a first position in which the substrate is secured in place relative to the clamp body and a second position in which the substrate is released; a guide mechanism that connects the clamp body to the base while allowing the clamp body to move freely relative to the base within a predetermined movable range; a fixing mechanism that switches a connection between the clamp body and the base between a fixed position in which the clamp body is fixed to the base and a free position in which the clamp body is movable relative to the base; The method comprises: moving the clamp body laterally over the substrate; lowering the clamp body onto the substrate; switching the locking mechanism to the free position; switching the actuator to the first position; switching the locking mechanism to the locking position; lifting the clamp body and the substrate and moving the clamp body to another location; switching the actuator to the second position; and lifting the clamp body without the substrate.

16. The step of switching the locking mechanism to the locking position includes increasing the pressure in the first vacuum line to a first threshold P ｔｈｒ１ 16. The method of claim 15, comprising reducing the

17. The step of switching the locking mechanism to the free position includes increasing the pressure in the first vacuum line to a second threshold P ｔｈｒ２ 17. The method of claim 15 or 16, comprising increasing the concentration of

18. The step of switching the actuator to the second position includes increasing the pressure in the second vacuum line to a third threshold P ｔｈｒ３ and / or switching the actuator to the first position reduces the pressure in the second vacuum line below a fourth threshold P ｔｈｒ４ 18. The method of claim 15, comprising increasing the concentration of

19. 19. A method according to any of claims 15 to 18, comprising projecting a patterned beam of radiation onto a substrate.

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