Electrostatic clamp, clamp assembly including the clamp, lithography system including the electrostatic clamp, and method of

Abstract

The invention provides an electrostatic clamp for clamping an object. The electrostatic clamp comprises an electrode layer; a first isolation layer comprising an electrically isolating flexible material disposed on top of the electrode layer, the first isolation layer having a first thickness; a first shielding layer including a conductive material disposed on top of the first isolation layer, the first shielding layer having a first shielding thickness and a cutout pattern for exposing the electrode layer covered with the first isolation layer; and a plurality of knots at a height of at least 1 m and arranged on top of the first shielding layer at the location of the cut-out pattern.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to EP application 22210278.2, filed on November 29, 2022, and the entire content of the EP application is incorporated herein by reference. Technical field

[0003] The present invention relates to an electrostatic chuck. The present invention also relates to a method of manufacturing a chuck and a method of using a chuck to hold an object. The object can be, for example, a substrate for a lithography process, such as a wafer, a reticle, or a mask. The chuck can be included, for example, in a robotic arm for transporting an object from one position to another position. Background art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, to manufacture integrated circuits (ICs). For example, a lithographic apparatus can project a pattern at a patterning device (e.g., a mask) onto a layer of radiation - sensitive material (resist) provided on a substrate.

[0005] To project a pattern onto a substrate, a lithographic apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum feature size that can be formed on the substrate. Compared to a lithographic apparatus that uses radiation having a wavelength of, for example, 193 nm, a lithographic apparatus that uses extreme ultraviolet (EUV) radiation having a wavelength 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 the substrate.

[0006] Electrostatic chucks typically hold and support a substrate during a lithography manufacturing process and also remove heat from the substrate without mechanically clamping the substrate. During the use of an electrostatic chuck, the backside of a substrate, such as a semiconductor wafer, is held against the surface of the electrostatic chuck by an electrostatic force. The substrate is separated from one or more electrodes in the surface of the electrostatic chuck by a surface layer of a material covering the electrodes. In a Coulombic chuck, the surface layer is electrically insulating, while in a Johnsen - Rahbek electrostatic chuck, the surface layer is weakly conductive. The surface layer of the electrostatic chuck can be flat or can have one or more protrusions, projections, or other surface features that further separate the backside of the substrate from the underlying electrodes. Heat transferred to the substrate during processing can be transferred from the substrate to the electrostatic chuck, for example, by contact heat conduction with the protrusions and / or by gas heat conduction with a cooling gas.

[0007] In microelectronic production, as the geometries of semiconductor and memory devices are gradually reduced and the sizes of wafers, flat panel displays, masks, and other processed substrates are gradually increased, the allowable particle contamination process specifications become more stringent. Since the wafer physically contacts or is mounted to the chuck gripping surface, the impact of particles on the electrostatic chuck is of particular concern. If any particles are allowed to be trapped between the mounting surface of the electrostatic chuck and the substrate, the substrate may be deformed due to the trapped particles. For example, if the backside of the wafer is electrostatically clamped to a flat reference surface, the trapped particles may cause the front side of the wafer to deform, so that the front side of the wafer will not lie in a flat plane. The actual height and diameter of the particle-induced displacement depend on a large number of parameters, such as particle size, particle hardness, clamping force, and mask thickness.

[0008] The robotic gripper may also include an electrostatic chuck. The robotic gripper can generally be included in a wafer handler. A wafer handler is a device that can be used to transfer substrates (such as wafers, masks, etc.) from one location to another.

[0009] Techniques comparable to those of the electrostatic chuck of the wafer platform can be used to fabricate the electrostatic chuck of the robotic gripper. However, the fabrication techniques for fabricating the robotic gripper chuck generally do not adequately balance the requirements of its gripper components. These requirements can include the potential energy of the anodic bond, the ability to withstand HF etching, and the ability to handle warped substrates within a certain range. In addition, the wafer handler chuck must operate at a much lower voltage (e.g., at about 1.6 kV instead of 3.2 kV) than the wafer platform chuck. Therefore, the electrostatic chuck of the wafer gripper tends to have relatively limited tolerance for warped substrates, increasing the risk of substrate slippage. In this document, "substrate slippage" refers to the sliding and dropping of a substrate (such as a wafer) from the gripper of the handler. The latter usually results in the loss of the corresponding substrate, thus reducing the throughput.

[0010] The current chuck is rigid (due to the glass structure) and can warp up to 40 µm across the width of one chuck (with a diameter of about 40 mm). The clamping pressure is insufficient to flatten the chuck against the wafer (against a flat wafer, let alone a warped wafer). In the case where the vacuum gap is designed to be, for example, a lower limit of about 10 µm, in practice, each chuck only makes three knuckle contacts, and the average vacuum gap may be (far) below the preferred setting, thus reducing the actual clamping pressure to below the design specifications expected at a specific voltage. This may cause the chuck of the robotic gripper to slide relative to the wafer, and thus damage the knuckles and the wafer, limiting the life and generating contamination. The resulting damage is related to the reduced availability (uptime).

[0011] US2012 / 0196242 discloses a substrate support that may include a plurality of substrate support pins. The plurality of substrate support pins may support the back surface of a substrate. In some embodiments, a support layer may be disposed on a first surface of a first member and each of the plurality of substrate support pins may extend from a surface of the support layer. In some embodiments, the support layer and each of the plurality of substrate support pins may be formed of the same material. For example, the support layer and each of the substrate support pins may be a one-piece structure. The support layer and each of the plurality of substrate support pins may be formed of a suitable process-compatible material having wear-resistant properties. For example, the material may be compatible with the substrate, compatible with the processes to be performed on the substrate, etc. In some embodiments, the support layer and / or the substrate support pins may be made of a dielectric material. In some embodiments, the material used to form the support layer and / or the substrate support pins may include polyimide (such as KAPTON ® ), alumina (Al2O3), aluminum nitride (AlN), silicon dioxide (SiO2), silicon nitride (Si3N4), etc. In some embodiments, for example, for low-temperature applications (e.g., at temperatures below about 200 degrees Celsius), the support layer and / or the substrate support pins may include KAPTON ® .

[0012] DE102004059122A1 discloses an electrostatic chuck (EC) for, for example, fixing a thin semiconductor wafer to a surface, having an array of conductive electrodes (E) and a dielectric that insulates the electrodes from the wafer at least at the holding surface. A conductive and elastic layer located at the electrode array allows for movement offset (ΔT) via thermal expansion without damage to the wafer surface.

[0013] Although the electrostatic chuck of DE102004059122A1 and the substrate support of US2012 / 0196242 may be well-suited for some applications, like other conventional systems, the electrostatic chuck of DE102004059122A1 and the substrate support of US2012 / 0196242 have proven to be unsuitable for use in the jaws of a robotic gripper. SUMMARY OF THE INVENTION

[0014] The present invention aims to provide an improved electrostatic chuck to alleviate at least some of the disadvantages mentioned above. The object of the present invention is to provide an improved chuck suitable for a wafer handler that is capable of handling a wider range of substrates.

[0015] The present disclosure provides an electrostatic chuck for gripping an object, comprising:

[0016] an electrode layer;

[0017] A first isolation layer, the first isolation layer including an electrically isolating flexible material disposed on top of the electrode layer, the first isolation layer having a first thickness;

[0018] A first shielding layer, the first shielding layer including a conductive material disposed on top of the first isolation layer, the first shielding layer having a first shielding thickness and a cutout pattern for exposing the first isolation layer; and

[0019] A plurality of protrusions, the plurality of protrusions being disposed on top of the first shielding layer at the locations of the cutout pattern and having a height between 1 µm and 50 µm, wherein the protrusions are electrically connected to the first shielding layer.

[0020] In an embodiment, the electrode layer is disposed on a second isolation layer.

[0021] In an embodiment, the electrostatic chuck includes: a second shielding layer, the second shielding layer including a conductive material disposed on the second isolation layer; and a third isolation layer disposed on the second shielding layer.

[0022] In an embodiment, the electrostatic chuck includes an electrical connection member that connects the first shielding layer and / or the second shielding layer for grounding and connects the electrode layer to a voltage source.

[0023] In an embodiment, the conductive material of the second layer includes chromium nitride (CrN); and / or the protrusions are made of a material including chromium nitride (CrN).

[0024] In an embodiment, the flexible material of the first isolation layer includes Kapton ® (polyoxydiphenylene pyromellitimide). In another embodiment, the flexible material of the first isolation layer includes Mylar ® (BOPET: biaxially oriented polyethylene terephthalate).

[0025] In an embodiment, the second thickness is in the range of 0.5 µm to 10 µm; and / or

[0026] The first thickness is in the range of 50 µm to 250 µm.

[0027] According to another aspect, the present disclosure provides a gripper assembly for transferring an object from one position to another position, the gripper assembly including:

[0028] A support structure,

[0029] A laminate of a plurality of layers disposed on the support structure, the laminate at least including:

[0030] Electrode layer;

[0031] A first isolation layer, the first isolation layer comprising an electrically isolating flexible material disposed on top of the electrode layer, the first isolation layer having a first thickness;

[0032] A first shielding layer, the first shielding layer comprising a conductive material disposed on top of the first isolation layer, the first shielding layer having a first shielding thickness and a cutout pattern for exposing the first isolation layer; and

[0033] A plurality of nodules, the plurality of nodules being disposed on top of the first shielding layer at the locations of the cutout pattern and having a height between 1 µm and 50 µm.

[0034] In an embodiment, the laminate further comprises a second isolation layer, the second isolation layer comprising an electrically isolating flexible material, and the electrode layer is disposed on the second isolation layer.

[0035] In an embodiment, the laminate further comprises:

[0036] A second shielding layer, the second shielding layer being a conductive material disposed on the second isolation layer; and

[0037] A third isolation layer disposed on the second shielding layer.

[0038] In an embodiment, the support structure comprises a plurality of fingers, each finger having an end provided with one of the at least one cutout pattern.

[0039] In an embodiment, the support structure comprises at least one opening, and each of the at least one cutout pattern covers a corresponding opening.

[0040] In an embodiment, the support structure has three fingers, each finger having an end provided with a corresponding opening.

[0041] In an embodiment, a damping material is disposed in at least one opening.

[0042] In an embodiment, the laminate extends from one end of the support structure to a second end, the one end being provided with at least one cutout pattern, the second end being provided with an electrical connector, wherein at least the electrode layer and the first shielding layer are electrically connected to the electrical connector.

[0043] In an embodiment, the conductive material comprises chromium nitride (CrN); and / or wherein the nodules are made of a material comprising chromium nitride (CrN).

[0044] In an embodiment, the flexible material comprises Kapton® or Mylar ® 。

[0045] In an embodiment, the second thickness is in the range of 0.5 µm to 10 µm; and / or the first thickness is in the range of 50 µm to 250 µm.

[0046] According to yet another aspect, the present disclosure provides a lithography system, the lithography system including at least one of the electrostatic chucks or the gripper assemblies described above.

[0047] According to another aspect, the present disclosure provides a method of manufacturing a gripper assembly including an electrostatic chuck, the method including the steps of:

[0048] Providing a support structure,

[0049] Manufacturing a multi-layer laminate, the laminate including at least:

[0050] Providing an electrode layer;

[0051] Disposing a first layer of electrically insulating flexible material on top of the electrode layer, the first layer having a first thickness;

[0052] Disposing a first shielding layer including a conductive material on top of the first insulating layer, the first shielding layer having a first shielding thickness and at least one cutout pattern for exposing the first insulating layer;

[0053] Setting at least one plurality of protrusions at least 1 µm high on top of the first shielding layer at the location of the cutout pattern; and

[0054] Disposing the laminate on the support structure.

[0055] In an embodiment, the step of manufacturing the laminate further includes:

[0056] Disposing a second insulating layer including an electrically insulating flexible material on the electrode layer;

[0057] Disposing a second shielding layer of conductive material on the second insulating layer; and

[0058] Disposing a third insulating layer on the second shielding layer.

[0059] In an embodiment, the method includes the steps of:

[0060] Providing a support structure having at least one opening; and

[0061] Covering at least one opening with a fixture section of the laminate, the fixture section including a cutout pattern.

[0062] In an embodiment, the method includes the step of disposing damping material in at least one opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0064] - Figure 1 depicts a lithographic system including a lithographic apparatus and a radiation source;

[0065] - Figure 2 a perspective view depicting an example of a conventional gripper assembly;

[0066] - Figure 3 a schematic top view depicting an embodiment of an electrostatic chuck according to the present disclosure;

[0067] - Figure 4 a schematic side view depicting an embodiment of an electrostatic chuck according to the present disclosure;

[0068] - Figures 5A to 5G a top view depicting a corresponding layer of an embodiment of an electrostatic chuck according to the present disclosure;

[0069] - Figure 5H depicts Figure 5D a top view of an alternative embodiment of the layer shown in; and

[0070] - Figure 6 an exploded perspective view depicting a stack of layers of an embodiment of an electrostatic chuck;

[0071] - Figure 7 a schematic side view depicting an embodiment of an electrostatic chuck according to the present disclosure included in a gripper assembly;

[0072] - Figure 8 a schematic side view depicting another embodiment of an electrostatic chuck according to the present disclosure included in a gripper assembly; and

[0073] - Figure 9 a perspective view depicting an embodiment of a gripper assembly according to the present disclosure. DETAILED DESCRIPTION

[0074] Figure 1 shows a lithographic system including a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and supply the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA includes an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W.

[0075] The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the patterning device MA. Additionally, the illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. The faceted field mirror device 10 and the faceted pupil mirror device 11 together provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. In addition to or instead of the faceted field mirror device 10 and the faceted pupil mirror device 11, the illumination system IL may include other mirrors or devices.

[0076] After being conditioned in this way, the EUV radiation beam B interacts with the patterning device MA. Due to this interaction, a patterned EUV radiation beam B’ is produced. The projection system PS is configured to project the patterned EUV radiation beam B’ onto the substrate W. For this purpose, the projection system PS may include a plurality of mirrors 13, 14 configured to project the patterned EUV radiation beam B’ onto the substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B’, thus forming an image with features smaller than the corresponding features on the patterning device MA. For example, a reduction factor of four or eight may be applied. Although the projection system PS is illustrated in Figure 1 as having only two mirrors 13, 14, the projection system PS may include a different number of mirrors (e.g., six or eight mirrors).

[0077] The substrate W may include a previously formed pattern. In this case, the lithographic apparatus LA aligns the image formed by the patterned EUV radiation beam B’ with the pattern previously formed on the substrate W.

[0078] A relative vacuum may be provided in the radiation source SO, in the illumination system IL, and / or in the projection system PS, i.e., a small amount of gas (e.g., hydrogen) at a pressure far below atmospheric pressure.

[0079] Figure 1The radiation source SO shown belongs to a type that can be referred to as, for example, a laser-produced plasma (LPP) source. A laser system 1 that can include, for example, a CO2 laser is arranged to deposit energy into a fuel (such as tin (Sn)) provided by a fuel emitter 3, for example, via a laser beam 2. Although tin is mentioned in the following description, any suitable fuel can be used. The fuel can be in liquid form, for example, and can be a metal or an alloy. The fuel emitter 3 can include a nozzle configured to guide the tin, for example, in the form of droplets, along a trajectory towards a plasma formation region 4. The laser beam 2 is incident on the tin at the plasma formation region 4. Depositing the laser energy into the tin generates a tin plasma 7 at the plasma formation region 4. Radiation including EUV radiation is emitted from the plasma 7 during the de-excitation and recombination of the electrons and ions of the plasma.

[0080] The EUV radiation from the plasma is collected and focused by a collector 5. The collector 5 includes, for example, a near-normal incidence radiation collector 5 (sometimes more commonly referred to as a normal incidence radiation collector). The collector 5 can have a multilayer mirror structure arranged to reflect EUV radiation (for example, EUV radiation having a desired wavelength such as 13.5 nm). The collector 5 can have an ellipsoidal configuration having two foci. The first of the foci can be at the plasma formation region 4, and the second of the foci can be at an intermediate focus 6, as discussed below.

[0081] The laser system 1 can be spatially separated from the radiation source SO. In this case, the laser beam 2 can be transmitted from the laser system 1 to the radiation source SO by means of a beam delivery system (not shown) that includes, for example, suitable guiding mirrors and / or beam expanders and / or other optical devices. The laser system 1, the radiation source SO, and the beam delivery system can be considered together as a radiation system.

[0082] The radiation reflected by the collector 5 forms an EUV radiation beam B. The EUV radiation beam B is focused at the intermediate focus 6 to form an image at the intermediate focus 6 of the plasma present at the plasma formation region 4. The image at the intermediate focus 6 serves as a virtual radiation source for an illumination system IL. The radiation source SO is arranged such that the intermediate focus 6 is at or near an opening 8 in an enclosure structure 9 of the radiation source SO.

[0083] Although Figure 1 the radiation source SO is depicted as a laser-produced plasma (LPP) source, any suitable source such as a discharge-produced plasma (DPP) source or a free electron laser (FEL) can be used to generate EUV radiation.

[0084] Figure 2An example of a gripper assembly GA for transferring an object from one location to another is shown. The object can be a substrate. In this document, a substrate can include, but is not limited to, a wafer, a reticle, and a mask. Although the respective locations can be inside the lithographic apparatus LA, they can also be outside the apparatus. That is, the gripper assembly can be part of a substrate handler for transferring a substrate from outside the lithographic apparatus to inside the apparatus, and vice versa. Generally, a lithographic apparatus includes an air lock for transferring a substrate from an atmospheric environment to a vacuum environment inside the lithographic apparatus.

[0085] The gripper assembly GA generally includes a support structure 20 provided with one or more electrostatic chucks CL for holding a substrate. The support structure 20 can include one or more fingers 22, 24, 26 extending outwardly from a body 28 of the support structure. Each finger can be provided with a respective chuck CL. The chucks can be arranged at the ends of the respective fingers.

[0086] For example, a conventional electrostatic chuck can include bosses made of anodically bonded glass, with a chromium electrode clamped between the bosses. The glass bosses can be etched on top of the electrode to keep the distance between the wafer and the chuck constant and to allow particles to be located between the wafer and the chuck without disturbing the lithographic process. Conventionally, each chuck is connected to a flexible power cable 30 via an electrical connector 32 and a power line 34. The power cable 30 is arranged to supply a high voltage to the electrostatic chuck. The power line has branches 36 extending to the respective electrostatic chucks.

[0087] A problem with conventional devices relates to the relatively fragile electrical connector 32. The connector 32 connects a high voltage source to a conductive layer having a thickness of approximately 100 nm. Therefore, the connector 32 is cumbersome to manufacture and is prone to damage.

[0088] As a solution, an electrostatic chuck can be constructed using an embodiment of an electrostatic chuck as discussed below, which optionally includes power lines 34, 36 and optionally also includes at least a portion of the power cable 30. Thus, the electrostatic chuck can be manufactured as a laminate. The laminate can constitute the electrostatic chuck and the associated power cable and its branches. This avoids the construction of a fragile electrical connector, reduces the chance of failure, and greatly simplifies and accelerates the construction, thereby reducing the associated costs.

[0089] Generally refer to Figure 3 、 Figure 4 、Figure 5 and Figure 6, an electrostatic chuck CL for holding a substrate may include a laminate including a plurality of stacked layers. The electrostatic chuck CL includes an electrode layer 40. A first isolation layer 42 including an electrically insulating flexible material is disposed on top of the electrode layer 40. The first isolation layer has a first thickness. A first shielding layer 44 of a conductive material is disposed on top of the first isolation layer 42. The first shielding layer has a first shielding thickness. The first shielding layer 44 is provided with a cutout pattern 46 for exposing the electrode layer covered with the first isolation layer. See, for example Figure 3 .

[0090] A plurality of nodules 48 are disposed on top of the first shielding layer 44 at the location of the cutout pattern 46. In this context, the phrase “at the location of the cutout pattern” means that the nodules 48 are disposed on top of the conductive material of the first shielding layer. The nodules 48 may be at least partially surrounded by the cutout pattern 46. Typically, the nodules may be composed of a conductive material. The material may be the same material as the conductive material of the conductive layer 44. In this context, the term “nodule” may refer to, for example, a stake, a column, or a raised structure.

[0091] The nodules may have a height between 1 µm and 50 µm, preferably between 2 µm and 20 µm, more preferably between 5 µm and 12 µm. Although Figure 3 four nodules are shown, the chuck CL may include any number of nodules suitable for supporting the substrate. The chuck CL may include, for example, at least three nodules. In a practical embodiment, the electrostatic chuck may include nodules in the range of about 10 to 100 nodules, such as about 20 to 50 nodules.

[0092] The cutout pattern 46 of the conductive material of the first shielding layer 44 provides a pattern of lines 50. The pattern may be a Manhattan pattern. Alternative patterns may also be contemplated. The nodules 48 may be electrically connected to each other and (via the lines 50) electrically connected to the first shielding layer 44.

[0093] In an embodiment, the laminate of the electrostatic chuck CL may include additional layers. The laminate of the plurality of layers may include a second isolation layer 60. The second isolation layer 60 may be disposed adjacent to the electrode layer on a side opposite to the first isolation layer 42. The laminate of the electrostatic chuck CL may include a second shielding layer 62. The second shielding layer generally includes a conductive material. The second shielding layer 62 may be covered by a third isolation layer 64.

[0094] The electrode layer may be connected to a voltage source. The voltage source may typically provide a high voltage on the order of 1 kV to 3 kV. The first shielding layer and the second shielding layer may be connected to ground (0 V), thereby shielding the electric field generated by the electrode layer 42.

[0095] The conductive material of the electrode layer 42 and / or the second shielding layer may include metals such as copper, iron, iron composite materials, titanium, silver, gold, etc. Combinations of metals are also conceivable.

[0096] The first isolation layer 42, the second isolation layer 60, and the third isolation layer 64 may include suitable isolation polymers. The polymers of all the isolation layers may be the same. Alternatively, different isolation materials may be used for each isolation layer. Details of the actual embodiments are described below.

[0097] In an alternative embodiment, referring to Figure 5H , the electrode layer 40 may include a first section 70 and a second section 72 arranged with an interspacing 74. The spacing 74 is preferably sufficient to allow a voltage difference between the first section 70 and the second section 72. For example, during the use of an electrostatic chuck, the first section may operate at a positive voltage while the second section 72 may operate at a negative voltage, or vice versa. The positive voltage may be in the range of 0.5 kV to 3 kV, for example about 1 kV. The negative voltage may be in the range of -0.5 kV to -3 kV, for example about -1 kV.

[0098] Referring to Figures 3 to 6 , the corresponding layers of the electrostatic chuck CL of the present disclosure may include chuck sections 80. The corresponding stacked layers as described above and illustrated in the figures may operate as the electrostatic chuck CL. The corresponding layers may also include cable sections 82. Only partially shown in Figures 3 to 6 , the cable section 82 may extend further and along an arbitrarily selected path. Referring to Figure 9 , the cable sections 82 of the corresponding layers may combine to form a branch 36 and optionally also form a cable connection section 34 and optionally also form at least a part of a flexible cable 30. A connector 31 may be provided at the end of the cable 30 to allow connection to, for example, a voltage source.

[0099] Referring to Figure 7 , the support structure 20 is provided with one or more openings 84. Typically, at least one opening 84 may be provided at the end of the respective fingers 22, 24, 26 of the support structure 20. Relative to Figures 3 to 6 The laminate of the plurality of layers described is arranged on the support structure 20. Herein, the chuck section 80 may be arranged to cover at least one opening 84. Thus, the cable section 82 may be supported by the support structure 20 while the chuck section 80 is at least partially freely suspended above the opening 84. The suspended chuck section may be mounted like a membrane, thereby allowing increased compliance with the shape of the substrate.

[0100] Generally referring to Figure 8, in an embodiment, at least one opening 84 may be provided with a piece of damping material 86. The damping material may include a viscoelastic material. The material may be an elastomer, such as a high-performance fluorinated elastomer, such as Viton™. The damping material will suppress vibrations in the substrate.

[0101] The inherent flexibility of one or more isolation and flexible layers 42, 60, 64 combined with the relatively thin shielding layer and electrode layers allows the laminate structure to be flexible and to be used as a cable for transmitting voltage to the fixture. Thus, the laminate serves as a power cable (optionally provided with connectors) and an electrostatic fixture connected to the cable. See, for example Figure 9 . In the present disclosure, a laminate having a fixture section 80 and a cable section 82 is disposed on a support structure 20. A connector 31 may be provided at the end of the cable section 82.

[0102] The laminate, optionally including the connector 31, may be integrally constructed and then disposed on the support structure 20 of the gripper assembly. This avoids the high-voltage connections that are prone to failure and difficult to perform on layers about 100 nm thick. As an alternative, the laminate may be fabricated, the laminate may be disposed on the support structure 20, and then bosses may be provided.

[0103] One of the driving factors for the electrostatic fixture of the present disclosure is that the technology for manufacturing flexible cables is relatively inexpensive, fast, and reliable. The technology for manufacturing flexible cables is known from the production of electronic components. Current manufacturing equipment allows for perfect dimensional accuracy, resistance control, and the production of long continuous lengths.

[0104] In a first step, the respective layers 40, 42, 60, 62, and 64 are positioned and joined on top of each other to form a laminate of multiple layers. Joining the respective layers may be accomplished using, for example, thermoforming.

[0105] In a subsequent step, the laminate of multiple layers is cut into a predetermined shape. Cutting the shape may be accomplished using, for example, laser cutting.

[0106] The laser cutting step may be combined with the step of depositing a coating to form the shielding layer 44 and / or the bosses 48. In the present disclosure, deposition may include, for example, physical vapor deposition (PVD), triode sputtering, magnetron sputtering, or ion beam assisted deposition (IBAD). Alternatively, depositing the coating may involve a lithography process that involves a resist for generating the pattern 46 and the material for depositing the coating.

[0107] Next, the connector 31 may be connected to the laminate.

[0108] Subsequently, the laminate may be applied to the support structure 20 of the gripper assembly GA ( Figure 9 ).

[0109] Compared with conventional methods of connecting fixtures, as described in reference Figure 2 The method of manufacturing a gripper assembly having one or more electrostatic chucks according to the present disclosure is very fast and inexpensive.

[0110] The layers between the outer layers 44, 64 are all uniform and have the same shape. This includes the electrode layer.

[0111] The isolation layer 42 below the shielding layer 44 and the boss 48 together define the electrostatic field strength. The material of the isolation flexible layer 42 acts as a dielectric. The boss defines the distance between the substrate placed on top of the boss and the electrode. The voltage of the electrode layer can be controlled.

[0112] The cut pattern 46 of the structured layer 44 defines the electrostatic gripping function of the layer.

[0113] The bosses 48 may be difficult to mask or may be made entirely of a relatively hard and wear-resistant material. The bosses provide a relatively fast, inexpensive but robust way to define the gap (and thus the gripping force) between the dielectric of layer 42 and the substrate wafer.

[0114] The fixture may include an electrical connection connected to the second patterned layer 44. The electrical connection may allow a predetermined potential of the conductive layer 44. The wire pattern 50 made of a conductive material connects the bosses 48 to a predetermined potential. This potential is typically grounded or connected to ground, and the reference value is determined to be 0V. Thus, the conductive layer 44 can act as a shielding layer, shielding the potential of the electrode layer 40. The electrode layer is exposed only at the positions of the openings of the cut pattern 46, allowing its electric field to provide an electrostatic gripping force.

[0115] The electrode layer 40 can be connected to a voltage potential. This voltage potential can typically be a high voltage in the order of, for example, 0.5 kV or higher. In a practical embodiment, the voltage can be in the range of about 1 kV to 3.5 kV.

[0116] Here, the isolation layer 42 covering the electrode layer can act as a dielectric. A dielectric is an insulating material or a very poor conductor of electric current. When a dielectric is placed in an electric field, since the dielectric does not have free electrons that can drift through the material, practically no current flows in the dielectric. Instead, electrode polarization occurs. The positive charges within the dielectric are slightly displaced in the direction of the electric field, and the negative charges are slightly displaced in the direction opposite to the electric field. This slight charge separation or polarization reduces the electric field within the dielectric.

[0117] The conductive material of the second layer 44 can be made of a wear-resistant and conductive material. The second layer can be applied as a coating. The second layer can include chromium nitride (CrN).

[0118] The bump can be made of the same material as the conductive layer 44. The bump can be made of a material including chromium nitride (CrN).

[0119] The CrN included in the electrostatic chuck of the present disclosure is preferably conductive. The conductivity of CrN can be controlled, for example, by adjusting the amount of chromium relative to the amount of nitride. In an actual embodiment, the conductive shielding layer including CrN has a total resistance of no more than 250 ohms from the CrN coating to the electrical connection cable 30. Herein, the measurement points cover the entire CrN coating 44. The typical resistance of the conductive coating is, for example, about 10 ohms to 30 ohms. For the bump made of CrN, the resistance value may reach 100 ohms to 400 ohms.

[0120] In an actual embodiment, the resistivity of the conductive material (such as CrN) of the coating 44 can be in the range of 10 Ohm*m (ohm * meter) to 5000 Ohm*m. The resistivity (usually denoted by the Greek letter rho (ρ)) is numerically equal to the resistance R of the sample (such as the coating) multiplied by its cross-sectional area A and then divided by its length l, so ρ = RA / l. The unit of resistivity is Ohm*m. Insulators have higher resistivity values, usually on the order of 10 10 Ωm or higher. In contrast, (metal) conductors can have very small resistivity values, such as on the order of 10 -8 Ωm.

[0121] For example, the flexible insulating material of the first insulating layer 42, the second insulating layer 60, and / or the third insulating layer can include polyimide (PI), a polymer containing an imide group belonging to the class of high-performance plastics, or can include polyester. In an actual embodiment, the insulating flexible material includes Kapton ® (a type of polyimide) or is made of Kapton ® (a type of polyimide). In another actual embodiment, the insulating flexible material includes Mylar ® (a type of biaxially oriented polyester (BOPET)) or is made of Mylar ® (a type of biaxially oriented polyester (BOPET)). The flexible material of the first insulating layer 42, the second insulating layer 60, and / or the third insulating layer 64 can have one or more properties in, but not limited to, for example, the following order: a Young's modulus of about 2.5 GPa to about 5 GPa, such as about 4 GPa; a tensile strength of about 80 MPa to about 90 MPa; an elastic range or elongation rate in the elastic range of about 4% to about 5%; a compressive strength of about 150 MPa to about 180 MPa; a fatigue strength of about 15 MPa to about 30 MPa; a flexural strength of about 100 MPa to about 130 MPa, such as about 115 MPa; and / or a Poisson's ratio of about 0.3 to about 0.35, such as about 0.34.

[0122] In a practical embodiment, the layer may have a thickness within a certain range. The second thickness of the second layer 44 may be in the range of 0.5 µm to 10 µm. The first thickness of the first insulating layer 42 may be in the range of 50 µm to 250 µm. The electrode layer 40 may have a thickness in the range of 0.1 µm to 1 µm. One or more nodules 48 may have a height in the range of 1 µm to 20 µm.

[0123] The thickness of the second insulating layer 60 may be in the range of 100 µm to 1 mm. The thickness of the third insulating layer 64 may be in the range of 100 µm to 1 mm. The second coating thickness of the second shielding layer 62 may be in the range of 0.1 µm to 1 µm.

[0124] Although reference may be specifically made herein to the use of a lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications. Possible other 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.

[0125] Although embodiments of the invention may be specifically referred to herein in the context of a lithographic apparatus, embodiments of the invention may be used in other apparatuses. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus for measuring or processing an object such as a wafer (or other substrate) or a mask (or other patterning device). These apparatuses may generally be referred to as lithographic tools. Such lithographic tools may use vacuum conditions or ambient (non-vacuum) conditions.

[0126] Although reference may be specifically made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that, where the context allows, the invention is not limited to optical lithography and may be used in other applications, such as imprint lithography.

[0127] Although specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced in other ways different from those described. The above description is intended to be illustrative, not restrictive. Thus, it will be apparent to those skilled in the art that the described invention may be modified without departing from the scope of the claims set forth below.

[0128] Example

[0129] 1. An electrostatic chuck for holding an object, comprising:

[0130] An electrode layer;

[0131] A first isolation layer, the first isolation layer including an electrically isolating flexible material disposed on top of the electrode layer, the first isolation layer having a first thickness;

[0132] A first shielding layer, the first shielding layer including a conductive material disposed on top of the first isolation layer, the first shielding layer having a first shielding thickness and a cutout pattern for exposing the first isolation layer; and

[0133] A plurality of protrusions, the plurality of protrusions being at least 1 µm high and disposed on top of the first shielding layer at the positions of the cutout pattern.

[0134] 2. The electrostatic chuck according to Example 1, wherein the electrode layer is disposed on a second isolation layer.

[0135] 3. The electrostatic chuck according to Example 2, comprising:

[0136] A second shielding layer, the second shielding layer including a conductive material disposed on the second isolation layer; and

[0137] A third isolation layer, the third isolation layer being disposed on the second shielding layer.

[0138] 4. The electrostatic chuck according to any one of the foregoing examples, comprising:

[0139] An electrical connection member, the electrical connection member connecting the first shielding layer and / or the second shielding layer for grounding, and the electrical connection member connecting the electrode layer to a voltage source.

[0140] 5. The electrostatic chuck according to any one of the foregoing examples,

[0141] wherein the conductive material of the second layer includes chromium nitride (CrN); and / or

[0142] wherein the protrusions are made of a material including chromium nitride (CrN).

[0143] 6. The electrostatic chuck according to any one of the foregoing examples, wherein the flexible material of the first layer includes Kapton ® or Mylar ® .

[0144] 7. The electrostatic chuck according to any one of the foregoing examples,

[0145] wherein the second thickness is in the range of 0.5 µm to 10 µm; and / or

[0146] wherein the first thickness is in the range of 50 µm to 250 µm.

[0147] 8. A gripper assembly for transferring an object from one position to another, the gripper assembly comprising:

[0148] A support structure,

[0149] A multi-layer laminate disposed on the support structure, the laminate at least comprising:

[0150] An electrode layer;

[0151] A first isolation layer comprising an electrically isolating flexible material disposed on top of the electrode layer, the first isolation layer having a first thickness;

[0152] A first shielding layer comprising a conductive material disposed on top of the first isolation layer, the first shielding layer having a first shielding thickness and a cutout pattern for exposing the first isolation layer; and

[0153] A plurality of protrusions at least 1 µm high and disposed on top of the first shielding layer at the positions of the cutout pattern.

[0154] 9. The gripper assembly according to Example 8, wherein the laminate further comprises a second isolation layer comprising an electrically isolating flexible material, and the electrode layer is disposed on the second isolation layer.

[0155] 10. The gripper assembly according to Example 9, wherein the laminate further comprises:

[0156] A second shielding layer which is a conductive material disposed on the second isolation layer; and

[0157] A third isolation layer disposed on the second shielding layer.

[0158] 11. The gripper assembly according to any one of Examples 8 to 10, wherein the support structure comprises a plurality of fingers, each finger having an end provided with one of the at least one cutout pattern.

[0159] 12. The gripper assembly according to any one of Examples 8 to 11, wherein the support structure comprises at least one opening, and each of the at least one cutout pattern covers a corresponding opening.

[0160] 13. The gripper assembly according to Example 12, wherein the support structure has three fingers, each finger having an end provided with a corresponding opening.

[0161] 14. The gripper assembly according to Example 12 or 13, wherein damping material is disposed in the at least one opening.

[0162] 15. The gripper assembly according to any one of Examples 8 to 14, wherein the laminate extends from one end of the support structure to a second end, the one end being provided with the at least one cut pattern, the second end being provided with an electrical connector, and wherein at least the electrode layer and the first shielding layer are electrically connected to the electrical connector.

[0163] 16. The gripper assembly according to any one of Examples 8 to 15, wherein the conductive material comprises chromium nitride (CrN); and / or wherein the nodules are made of a material comprising chromium nitride (CrN).

[0164] 17. The gripper assembly according to any one of Examples 8 to 16, wherein the flexible material comprises Kapton ® or Mylar ® .

[0165] 18. The gripper assembly according to any one of Examples 8 to 17,

[0166] wherein the second thickness is in the range of 0.5 µm to 10 µm; and / or

[0167] wherein the first thickness is in the range of 50 µm to 250 µm.

[0168] 19. A lithography system comprising at least one electrostatic chuck according to Example 1 or a gripper assembly according to Example 8.

[0169] 20. A method of manufacturing a gripper assembly comprising an electrostatic chuck, the method comprising the steps of:

[0170] providing a support structure,

[0171] manufacturing a laminate of multiple layers, the laminate comprising at least:

[0172] providing an electrode layer;

[0173] laying a first layer comprising an electrically insulating flexible material on top of the electrode layer, the first layer having a first thickness;

[0174] laying a first shielding layer comprising a conductive material on top of the first insulating layer, the first shielding layer having a first shielding thickness and at least one cut pattern for exposing the first insulating layer;

[0175] setting at least a plurality of nodules at least 1 µm high on top of the first shielding layer at the location of the cut pattern; and

[0176] laying the laminate on the support structure.

[0177] 21. The method as described in Example 20, wherein the step of manufacturing the layer laminate further comprises:

[0178] disposing a second isolation layer including an electrically insulating flexible material on the electrode layer;

[0179] disposing a second shielding layer of a conductive material on the second isolation layer; and

[0180] disposing a third isolation layer on the second shielding layer.

[0181] 22. The method as described in any one of Examples 20 or 21, comprising the steps of:

[0182] providing the support structure having at least one opening; and

[0183] covering the at least one opening with a clamp section of the layer laminate, the clamp section including the cut pattern.

[0184] 23. The method as described in Example 22, comprising the step of disposing a damping material in the at least one opening.

Claims

1. An electrostatic chuck for clamping an object, comprising: An electrode layer; A first isolation layer (42), the first isolation layer comprising an electrically isolating flexible material disposed on top of the electrode layer, the first isolation layer having a first thickness; A first shielding layer (44), the first shielding layer comprising a conductive material disposed on top of the first isolation layer, the first shielding layer having a first shielding thickness and a cut pattern for exposing the first isolation layer; And A plurality of protrusions (48), the plurality of protrusions being disposed on top of the first shielding layer and having a height between 1 µm and 50 µm.

2. The electrostatic chuck according to claim 1, wherein, The protrusions are at least partially surrounded by the cut pattern, and / or wherein the protrusions are electrically connected to each other and electrically connected to the first shielding layer.

3. The electrostatic chuck according to claim 2, wherein, The electrode layer is disposed on a second isolation layer, and the electrostatic chuck further comprises: A second shielding layer, the second shielding layer comprising a conductive material disposed on the second isolation layer; and A third isolation layer, the third isolation layer being disposed on the second shielding layer.

4. The electrostatic chuck according to any one of the preceding claims, comprising: An electrical connector that connects the first shielding layer and / or the second shielding layer for grounding, and the electrical connector connects the electrode layer to a voltage source.

5. The electrostatic chuck according to any one of the preceding claims, Among them, The conductive material of the second layer comprises chromium nitride (CrN); and / or Wherein, the protrusions comprise chromium nitride (CrN).

6. The electrostatic chuck according to any one of the preceding claims, wherein, The flexible material of the first isolation layer includes Kapton ® (polyoxydiphenylene pyromellitimide) or Mylar ® (biaxially oriented polyethylene terephthalate).

7. The electrostatic chuck according to any one of the preceding claims, Among them, The first shielding thickness is in the range of 0.5 µm to 10 µm; and / or Wherein, the first thickness is in the range of 50 µm to 250 µm.

8. A gripper assembly for transferring an object from one position to another, the gripper assembly comprising: A support structure, A laminated member of a plurality of layers disposed on the support structure, the laminated member at least comprising: An electrode layer; A first isolation layer, the first isolation layer comprising an electrically isolating flexible material disposed on top of the electrode layer, the first isolation layer having a first thickness; A first shielding layer, the first shielding layer comprising a conductive material disposed on top of the first isolation layer, the first shielding layer having a first shielding thickness and a cut pattern for exposing the first isolation layer; and A plurality of protrusions (48), the plurality of protrusions being disposed on top of the first shielding layer and having a height between 1 µm and 50 µm.

9. The gripper assembly according to claim 8, wherein the laminated member further comprises a second isolation layer, the second isolation layer comprising an electrically isolating flexible material, and the electrode layer is disposed on the second isolation layer.

10. The gripper assembly according to claim 9, wherein the laminated member further comprises: A second shielding layer, the second shielding layer being a conductive material disposed on the second isolation layer; And A third isolation layer disposed on the second shielding layer.

11. The gripper assembly according to any one of claims 8 to 10, wherein, The support structure comprises a plurality of fingers, and each finger has an end provided with one of the at least one cut pattern.

12. The gripper assembly according to any one of claims 8 to 11, wherein, The support structure includes at least one opening, and each of the at least one cut pattern covers a corresponding opening.

13. The gripper assembly according to claim 12, wherein, The support structure has three fingers, each finger having an end provided with a corresponding opening.

14. A lithography system comprising at least one electrostatic chuck according to claim 1 or a holder assembly according to claim 8.

15. A method of manufacturing a holder assembly including an electrostatic chuck, the method comprising the steps of: providing a support structure, manufacturing a multi-layer laminate, the multi-layer laminate at least including: providing an electrode layer; disposing a first layer of electrically insulating flexible material on top of the electrode layer, the first layer having a first thickness; disposing a first shielding layer including a conductive material on top of the first insulating layer, the first shielding layer having a first shielding thickness and at least one cut pattern for exposing the first insulating layer; providing a plurality of nodules having a height between 1 µm and 50 µm and disposed on top of the first shielding layer; and disposing the laminate on the support structure.

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