Apparatus and method for in-situ jig surface roughening

Abstract

A specialized roughening substrate is disclosed that is provided with abrasive elements suitable for in situ roughening the surface of a jig in a semiconductor lithography apparatus. A method of using the roughened substrate is also disclosed in which the roughened substrate is loaded, positioned opposite the jig, and then pressed toward the jig and moved laterally.

Description

[0001] Description of the case

[0002] This application is a divisional application of the Chinese national phase patent application of the PCT application with international application number PCT / EP2019 / 062252, international application date May 14, 2019, date of entry into the Chinese national phase on November 20, 2020, Chinese national application number 201980034220.7, and invention name “Device and method for in-situ fixture surface roughening”. Technical Field

[0003] The present disclosure relates to a chuck that may be used to hold a reticle or substrate in an apparatus for semiconductor lithography, and more particularly to the treatment of a surface of such a chuck that contacts a reticle or substrate. Background Art

[0004] A lithographic apparatus is a machine that applies a desired pattern to a substrate (usually applied to a target portion of a substrate). For example, a lithographic apparatus can be used in the manufacture of an integrated circuit (IC). In this case, a pattern forming device (alternatively referred to as a mask or reticle) can be used to generate a circuit pattern to be formed on a separate layer of the IC. The pattern can be transferred to a target portion (e.g., a portion including one or more bare chips) on a substrate (e.g., a silicon wafer). The pattern is usually transferred to a radiation-sensitive material (resist) layer disposed on the substrate via imaging. Typically, a single substrate will contain a network of adjacent target portions that are continuously patterned.

[0005] Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing the entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern by a radiation beam in a given direction (the "scanning" direction) while simultaneously scanning the substrate parallel or antiparallel to that direction. The pattern can also be transferred from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0006] An object (such as a pattern forming device or a substrate) is attached to an object support, such as a mask stage or a wafer stage, respectively, by using a clamp. An electrostatic clamp may be provided to electrostatically clamp an object to an object support. As a component for holding the object, the clamp is in contact with the object. It is necessary to roughen the surface of the clamp that is in contact with the object. Otherwise, even after the electrostatic clamping force is removed, the object still has a tendency to continue to adhere to the clamp because the extremely flat surfaces of the clamp and the object can stick via optical contact. This "stickiness" can complicate the removal of the object from the clamp and prolong the time required to remove the object from the clamp, or even make non-destructive removal impossible.

[0007] Throughout the life of the fixture, the fixture surface must be roughened periodically or, for example, when the fixture surface begins to exhibit stickiness. Fixture roughening is usually performed with the scanner / stepper offline and the fixture removed from its operating environment. This situation can result in a significant amount of downtime.

[0008] Therefore, there is a need for a system for roughening a fixture that reduces machine downtime. Summary of the invention

[0009] A simplified summary of one or more embodiments is presented below in order to provide a basic understanding of the embodiments. This summary is not an exhaustive overview of all contemplated embodiments and is not intended to identify key or important elements of all embodiments, nor is it intended to set limitations on the scope of any or all embodiments. Its sole purpose is to present some concepts of one or more embodiments in a simplified form as a prelude to a more detailed description that will be presented later.

[0010] According to one aspect of the embodiments, an apparatus and method are disclosed in which fixture roughening can be performed in situ by providing a roughened substrate that can be loaded in the same manner as a mask or substrate and then moved to the fixture's surface (s) that need to be roughened and pressed against the surface (s). The roughened substrate includes an abrasive element connected to a substrate base by a flexure so that the abrasive element can conform to the fixture's surface (s) and apply a substantially uniform normal force to the fixture surface (s). The abrasive element is then moved back and forth laterally to roughen the fixture surface (s).

[0011] According to another aspect of the embodiment, each abrasive element has a corresponding actuator, such as a piezoelectric element, that is controlled to laterally move the abrasive element.

[0012] According to another aspect of the embodiment, a device is disclosed, which includes a substrate base and a plurality of abrasive elements, each of which is mechanically coupled to the substrate base by a corresponding coupling element. The substrate base may include a mask base. Each of the corresponding abrasive elements may include a piezoelectric element, which is arranged to move the corresponding abrasive element laterally under the control of a control unit. Each of the corresponding coupling elements may include a corresponding flexure, which may be preloaded and may have a low spring constant in a direction substantially perpendicular to the substrate base. The spring constant is in the range of about 50N / m to about 5000N / m in a direction substantially perpendicular to the substrate base.

[0013] Each abrasive element in the plurality of abrasive elements may have substantially the same shape and size. The plurality of abrasive elements may be arranged in an array, which may be an ordered array. The array may substantially cover the substrate base.

[0014] Each of the abrasive elements may include a ceramic material.For each of the abrasive elements, a distance between the abrasive element and the backing base may be limited by a stop.

[0015] According to another aspect of the embodiment, a method for roughening the surface of a fixture in a semiconductor lithography apparatus is disclosed, the method comprising the following steps: loading a roughened substrate onto a stage, the roughened substrate having a face provided with a plurality of abrasive elements; aligning the roughened substrate with the fixture so that the surface of the fixture having the burls is opposite to the face of the roughened substrate having the abrasive elements; pressing the abrasive elements against the surface of the fixture; roughening the burls by translating the abrasive elements substantially in a plane substantially parallel to the surface of the fixture until a desired roughness is obtained; moving the roughened substrate away from the fixture; moving the roughened substrate to a position where the roughened mask can be unloaded from the stage; and unloading the roughened substrate from the stage. The step of translating the roughened substrate in a plane substantially parallel to the surface of the fixture until a desired roughness is obtained comprises: determining when the burls have a desired roughness. Determining when the desired roughness has been obtained comprises: determining when an amount of time known to produce the desired roughness has passed. Determining when the desired roughness has been obtained comprises: sensing the roughness of the burls. Roughening the burl by translating the abrasive element substantially in a plane substantially parallel to the surface of the fixture until a desired roughness is obtained may include moving the substrate. A plurality of abrasive elements may be mechanically coupled to respective actuators, and roughening the burl by translating the abrasive element substantially in a plane substantially parallel to the surface of the fixture until a desired roughness is obtained may include causing the actuators to move their respective abrasive elements substantially in a plane substantially parallel to the surface of the fixture. The actuators may include piezoelectric elements.

[0016] Further embodiments, features, and advantages of the subject matter of the present disclosure, as well as the structure and operation of the various embodiments are described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A lithographic apparatus according to aspects of an embodiment of the invention is depicted.

[0018] Figure 2 A partial cross section of a conventional edge clamp is depicted, and the clamp pressure is schematically illustrated.

[0019] Figure 3 is a plan view of a roughened substrate according to an aspect of an embodiment of the present invention.

[0020] Figure 4A is a cross-sectional view of a roughened substrate according to an aspect of an embodiment of the present invention.

[0021] Figure 4B is a cross-sectional view of a roughened substrate engaged with a fixture according to an aspect of an embodiment of the present invention.

[0022] Figure 5 is a flow chart illustrating a method of roughening a surface of a jig according to an aspect of an embodiment of the present invention.

[0023] Figure 6 is a plan view of a roughened substrate according to an aspect of another embodiment of the present invention.

[0024] Other features and advantages of the present invention and the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. Such embodiments are presented herein only for illustrative purposes. Based on the teachings contained herein, additional embodiments will be apparent to those skilled in the relevant art. DETAILED DESCRIPTION

[0025] Various embodiments are now described with reference to the drawings, wherein throughout the text, similar reference numerals are used to refer to similar elements. In the following description, for the purpose of explanation, many specific details are set forth to facilitate a thorough understanding of one or more embodiments. However, in some or all cases, it may be apparent that any embodiment described below may be practiced without the specific design details described below. In the following description and in the claims, the terms "upward", "downward", "top", "bottom", "vertical", "horizontal", etc. may be used. Unless otherwise indicated, these terms are intended only to show relative orientation, rather than any orientation relative to gravity.

[0026] Figure 1 A lithographic apparatus 100 according to an embodiment of the invention is schematically depicted. The apparatus comprises an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV radiation or EUV radiation), a support structure or support or pattern support (e.g. mask table) MT configured to support a patterning device (e.g. mask) MA and connected to a first positioner PM configured to accurately position the patterning device according to certain parameters, a substrate table (e.g. wafer stage) WT configured to hold a substrate (e.g. resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate 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 (e.g. comprising one or more dies) of the substrate W.

[0027] The illumination system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping or controlling the radiation.

[0028] The support structure holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as, for example, whether the patterning device is held in a vacuum environment. The support structure can hold the patterning device using mechanical, vacuum, electrostatic, or other clamping techniques. The support structure can be, for example, a frame or a stage, which can be fixed or movable as desired. The support structure can ensure that the patterning device is in a desired position, for example relative to a projection system. Any use of the term "reticle" or "mask" herein may be considered synonymous with the more general term "patterning device".

[0029] The term "patterning device" as used herein should be broadly interpreted as referring to any apparatus that can be used to impart a radiation beam with a pattern in its cross-section, such as to create a pattern in a target portion of a substrate. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so-called assist features. Typically, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device (such as an integrated circuit) being created in the target portion.

[0030] The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography and include various mask types, such as binary, alternating phase shift, and attenuated phase shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam, which is reflected by the matrix of mirrors.

[0031] The term "projection system" as used herein should be broadly interpreted to cover any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation used or other factors, such as the use of immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system".

[0032] The support structure and substrate table may also be referred to as article support hereinafter.Articles include, but are not limited to, patterning devices (such as reticles) and substrates (such as wafers).

[0033] As depicted herein, the device is reflective (eg, employing a reflective mask). Alternatively, the device may be transmissive (eg, employing a transmissive mask).

[0034] The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and / or two or more mask tables). In such a "multi-stage" machine the extra tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposure.

[0035] The lithographic apparatus may also be of a type in which at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, such as water, so as to fill the space between the projection system and the substrate. Immersion liquid may also be applied to other spaces in the lithographic apparatus, such as the space between the mask and the projection system. Immersion techniques for increasing the numerical aperture of the projection system are well known in the art. The term "immersion" as used herein does not mean that the structure (such as the substrate) must be immersed in the liquid, but only means that the liquid is located between the projection system and the substrate during exposure.

[0036] Reference Figure 1 , the illuminator IL receives a radiation beam from a radiation source SO. For example, when the source is an excimer laser, the source and the lithographic apparatus may be separate entities. In this case, the source is not considered to form a part of the lithographic apparatus, and the radiation beam is transferred from the source SO to the illuminator IL by means of a beam delivery system including, for example, suitable guide mirrors and / or a beam expander. In other cases, for example, when the source is a mercury lamp, the source may be an integral part of the lithographic apparatus. If desired, the source SO and the illuminator IL and the beam delivery system may be referred to as a radiation system.

[0037] The illuminator IL may include an adjuster for adjusting the angular intensity distribution of the radiation beam. Typically, at least the outer and / or inner radial extent of the intensity distribution in a pupil plane of the illuminator (commonly referred to as σ-outer and σ-inner, respectively) may be adjusted. In addition, the illuminator IL may include various other components, such as an integrator and a condenser. The illuminator may be used to adjust the radiation beam to have a desired uniformity and intensity distribution in its cross-section.

[0038] The radiation beam B is incident on a patterning device (e.g. a mask) MA held on a support structure (e.g. a mask table) MT and is patterned by the patterning device. After being reflected by the patterning device (e.g. a mask) MA, the radiation beam B passes through a projection system PS which focuses the beam onto a target portion C of the substrate W. With the aid of a second positioner PW and a position sensor IF2 (e.g. an interferometric measurement device, a linear encoder or a capacitive sensor), the substrate table WT can be accurately moved, for example in order to position different target portions C in the path of the radiation beam B. Similarly, a first positioner PM and a further position sensor IF1 can be used to accurately position the patterning device (e.g. a mask) MA relative to the path of the radiation beam B, for example after mechanical retrieval of the patterning device (e.g. a mask) MA from a mask library or during scanning. Typically, movement of the support structure (e.g. a mask table) MT can be achieved with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate table WT can be achieved using a long-stroke module and a short-stroke module, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the support structure (e.g., mask table) MT may be connected only to the short-stroke actuator, or may be fixed. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 may be used to align the pattern forming device (e.g., mask) MA and the substrate W. Although the substrate alignment marks as shown occupy dedicated target portions, these substrate alignment marks may be located in the space between the target portions (these substrate alignment marks are referred to as scribing alignment marks). Similarly, in the case where more than one die is disposed on the pattern forming device (e.g., mask) MA, the mask alignment marks may be located between the dies.

[0039] Figure 2 Depicted is a partial cross-section of an electrostatic chuck 110 that may be applied to the edge of an article such as a reticle or wafer. Figure 2 The clamp pressure that may be generated by the clamp is also schematically illustrated by the arrows in the figure. The clamp 110 includes a clamp lower portion 120 formed of an insulating material and a clamp upper portion 130 formed of a dielectric material. The clamp upper portion 130 is formed with a plurality of protuberances 140. The tops of the protuberances 140 determine the plane 150 in which the article (not shown) will be held. The first electrode 160 is disposed between the clamp lower portion 120 and the clamp upper portion 130, and the first electrode 160 is adapted to be held at a voltage (typically 3 kV) to generate an electrostatic clamping force. The ground electrode 170 is maintained grounded and is spaced apart from the first electrode 160 by a gap 180, which acts as a barrier between the first electrode and the ground electrode. The gap 108 may be filled with an insulating material, a dielectric material, or may be left empty.

[0040] Figure 2 The downward pointing arrow in the diagram schematically illustrates Figure 2 The clamping pressure that can be generated by the clamp of the embodiment of the present invention is shown in FIG. 1 . The length of the arrow indicates the clamping force, and it will be seen that a uniform clamping pressure can be generated across the width of the first electrode, the magnitude of which will depend on a number of parameters, including the applied voltage, the dielectric constant of the clamp upper portion 130, and the dimensions of the various portions of the clamp 110. When a voltage is applied to the electrode 160, the article can be held in the plane 150 by an electrostatic clamping force. Additional details regarding electrostatic clamps of this nature are disclosed, for example, in U.S. Patent No. 9,455,172, issued September 27, 2016, the entire contents of which are incorporated herein by reference.

[0041] As mentioned, in operation, the tops of the burls 140 contact the generally flat surface of the article to be held. This situation may result in optical contact adhesion of these surfaces, which may interfere with effective removal of the article from the fixture. To address this problem, the tops of the burls may be intentionally roughened to prevent complete optical contact. Typically, the surface roughness Ra (arithmetic mean of the absolute values ​​of the profile height deviations from the mean) is preferably in the range of about 3 nm to about 7 nm.

[0042] During use, due to wear, the burl top surface may become too smooth to make optical contact bonding possible again. When this happens, it is necessary to re-roughen the top of the burl. One way to accomplish this is to remove the fixture from the tool and roughen it manually. However, this results in significant downtime losses. Instead, it would be advantageous to have a system for repairing the burl top in situ with less downtime.

[0043] The following discussion uses a reticle as an example, but it should be understood that the disclosed principles can be applied to other clamped items, such as substrates. Figure 3 An example of a roughened mask 200 according to one aspect of an embodiment is shown. The roughened mask 200 includes an array of abrasive elements 210 mounted on a mask base 220 in a manner described below. The roughened mask 200 can be loaded into the tool like any other mask, but after the roughened mask is positioned facing the fixture, the roughened mask is pressed toward the fixture and moved laterally. This causes the abrasive elements 210, which are arranged to substantially cover the surface of the roughened mask 200, to contact the tops of the burls on the fixture and then roughen these tops. In Figure 2The abrasive elements 210 (e.g., ceramic "stones") on the arrangement are arranged in an ordered array as an example, but other arrangements are possible, including unordered arrays and arrays containing abrasive elements of different sizes and shapes. In addition, Figure 2 The array in is a 4X4 array, but it will be clear to one of ordinary skill in the art that other sized arrays may be used. The overall size of the array and abrasive elements 210 is selected so that the roughened mask is close enough to the size of the standard mask so that it is the same size as the standard mask so that equipment designed to work with the standard mask will also work with the roughened mask.

[0044] The abrasive element 210 may be composed of any material used to roughen a surface, such as a ceramic material. Other examples of materials that may be used include aluminum oxide and zirconium oxide.

[0045] Parameters related to the roughening process include: the amount of force applied to the abrasive element 210 as it slides on the fixture surface, the uniformity of the pressure between the abrasive element 210 and the burls 140 above the abrasive element area, and the roughness of the stone. One of the main challenges of in-situ roughening is to ensure uniform and consistent pressure across all reticle fixture burls. This design goal is met by the system described below. As for stone roughness, the same material can have a variety of different roughnesses. Typically, the range of stone roughness for use in the system disclosed herein is about 200nm to about 1000nm.

[0046] Figure 4A An example of a roughened reticle 200 is shown in accordance with one aspect of an embodiment. Roughened reticle 4A includes a plurality of abrasive elements 210 that together cover substantially the entire surface of a reticle base 220.

[0047] As mentioned, two parameters relevant to the roughening process are the amount of force applied to the abrasive element 210 as it slides over the fixture surface, and the uniformity of the pressure between the abrasive element 210 and the burls 140 over the abrasive element area. Most advantageously, the pressure is uniform and consistent across all of the reticle fixture burls. In order to control these parameters and as Figure 4A As shown in , each of the abrasive elements is provided with at least one flexure 230. The flexure 230 may be, for example, a spring. Figure 4B As shown in FIG. 1 , the flexure 230 is preloaded to ensure a uniform minimum normal force while conforming to the shape and flatness of the fixture 110 . The stop 240 limits the vertical travel of the abrasive element 210 under the preload from the flexure 230 .

[0048] Thus, each abrasive element 210 is attached to the reticle base 220 by a flexure 230. The flexure 230 is preloaded in the z-direction and is designed to have a low spring constant in the z-direction (i.e., to be "soft"). The flexure 230 has a spring constant in the range of about 50 N / m to about 5000 N / m in a direction substantially perpendicular to the reticle base 220. This ensures the desired consistency of the normal force between the fixture and the abrasive element, which will be approximately the same as the preload force.

[0049] The compliant preloaded flexure ensures compliance with the fixture surface. Each abrasive element in the abrasive element array is mechanically coupled to the mask base using a flexure that is preloaded in the z direction (orthogonal to the array corresponding to the xy plane), has a low spring constant (e.g., a spring) and has a low spring constant (soft) in z, Rx (rotation around the x-axis) and Ry (rotation around the y-axis), and has a higher spring constant (hardened) for all other degrees of freedom. The stopper 240 constrains the movement of the abrasive element in the z direction so that the abrasive element 210 maintains a predetermined distance from the mask base at most. Since the applied force is sufficient to overcome the preload for all abrasive elements 210, the low-elasticity spring allows a substantially constant elastic force within the displacement range in the z direction.

[0050] Therefore, if Figure 4B , the roughened reticle 200 is moved in the z direction so that when the abrasive elements 210 are pressed against the burls 140 on the fixture 110, the force generated by the displacement of the abrasive elements 210 overcomes the upward spring force applied by the flexure 230. In this condition, the force applied by the flexure 230 is substantially constant, thus applying a substantially constant normal force on the burls 140. Each abrasive element 210 contacts a certain number n of burls 140. Each abrasive element 210 conforms to the fixture surface independently.

[0051] Figure 51 is a flow chart of an example of a fixture roughening process using a roughened mask 200. In step S500, the roughened mask 200 is loaded onto the mask stage like a normal mask. Then, in step S510, the roughened mask 200 is aligned with the fixture 110 so that the surface of the fixture 110 having the burls 140 is opposite to the surface of the roughened mask 200 having the abrasive elements 210. In step S520, the mask stage is controlled to press the roughened mask 200 toward the fixture 110 so that the abrasive elements 210 will contact the burls 140 to achieve the desired contact force and displacement. The flexure 230 will deform to maintain a separate force of approximately the preload. In step S530, the mask stage is then commanded to translate the roughened mask 200 in the xy plane to perform polishing until the desired roughness is obtained. The desired roughness will have an Ra in the range of about 3 nm to about 7 nm. Then, in step S540, the roughened reticle 200 is pulled away from the fixture. Then, in step S550, the roughened reticle 200 is moved from the fixture to a position where the roughened reticle 200 can be unloaded. Then, in step S560, the roughened reticle 200 is unloaded from the reticle stage.

[0052] Step S530 may be terminated when a certain time of relative motion is performed to produce the desired surface roughness, which time is known a priori. Alternatively, performing part of step S530 may involve, for example, optically using sensor data to make a positive determination that the desired surface roughness has been obtained, in which case relative xy motion is performed until the determination is positive.

[0053] exist Figure 6 In the alternative embodiment shown in , each individual abrasive element 210 is individually actuated using an individual actuator 250 (e.g., using a piezoelectric element). The actuators 250 are under the control of a control unit 260 to move the corresponding abrasive elements 210 of these actuators laterally, i.e., in the xy plane. The force can be applied in a coordinated manner so that as the abrasive elements 210 move in different directions in the xy plane so that these movements cancel each other out as a whole, the total net applied lateral force will be substantially zero.

[0054] The embodiments may also be described using the following terms:

[0055] 1. A device comprising:

[0056] substrate base;

[0057] A plurality of abrasive elements, each of the abrasive elements being mechanically coupled to the backing base via a respective coupling element.

[0058] 2. The apparatus of clause 1, wherein the substrate pedestal comprises a reticle pedestal.

[0059] 3. The apparatus according to clause 1, further wherein each of the respective abrasive elements comprises a piezoelectric element arranged to laterally move the respective abrasive element under control of the control unit.

[0060] 4. The device according to clause 1, wherein each of the respective coupling elements comprises a respective flexure.

[0061] 5. Apparatus according to clause 4, wherein each respective flexure is preloaded.

[0062] 6. Apparatus according to clause 4, wherein each respective flexure has a low spring constant in a direction substantially perpendicular to the substrate base.

[0063] 7. The apparatus of clause 4, wherein each respective flexure has a spring constant in a direction substantially perpendicular to the substrate base in a range of about 50 N / m to about 5000 N / m.

[0064] 8. The device of clause 1, wherein each abrasive element in the plurality of abrasive elements has substantially the same shape and size.

[0065] 9. The device of clause 1, wherein the plurality of abrasive elements are arranged in an array.

[0066] 10. The apparatus of clause 9, wherein the array is an ordered array.

[0067] 11. The device according to clause 9, wherein the array substantially covers the substrate base.

[0068] 12. The device of clause 1, wherein each of the abrasive elements comprises a ceramic material.

[0069] 13. The apparatus of clause 1, wherein for each of the abrasive elements, a distance between the abrasive element and the backing base is limited by a stop.

[0070] 14. A method for roughening the surface of a fixture in a semiconductor lithography apparatus, the method comprising the following steps:

[0071] loading a roughened substrate onto a stage, the roughened substrate having a surface provided with a plurality of abrasive elements;

[0072] aligning the roughened substrate with the fixture so that the surface of the fixture having the burls is opposite the face of the roughened substrate having the abrasive elements;

[0073] pressing the abrasive element against the surface of the fixture;

[0074] roughening the burl by translating the abrasive element substantially in a plane substantially parallel to the surface of the fixture until a desired roughness is achieved;

[0075] removing the roughened substrate from the fixture;

[0076] moving the roughened substrate to a position where the roughened reticle can be unloaded from the stage; and

[0077] The roughened substrate is unloaded from the stage.

[0078] 15. The method of clause 14, wherein the step of translating the roughened substrate in a plane substantially parallel to the surface of the fixture until a desired roughness is achieved comprises determining when the burl has the desired roughness.

[0079] 16. The method of clause 15, wherein determining when a desired roughness has been achieved comprises determining when an amount of time known to produce the desired roughness has elapsed.

[0080] 17. The method of clause 15, wherein determining when a desired roughness has been achieved comprises sensing the roughness of the burl.

[0081] 18. The method of clause 14, wherein roughening the burl by translating the abrasive element substantially in a plane substantially parallel to the surface of the fixture until a desired roughness is achieved comprises: moving the substrate.

[0082] 19. A method according to claim 14, wherein a plurality of abrasive elements are mechanically connected to respective actuators, and wherein roughening the burl by translating the abrasive elements substantially in a plane substantially parallel to the surface of the fixture until a desired roughness is achieved comprises causing the actuators to move the respective abrasive elements of the actuators substantially in a plane substantially parallel to the surface of the fixture.

[0083] 20. The method of clause 19, wherein the actuator comprises a piezoelectric element.

[0084] The present disclosure is made with the aid of functional building blocks that illustrate implementations of specific functions and their relationships. For ease of description, the boundaries of these functional building blocks have been arbitrarily defined herein. Alternate boundaries may be defined as long as the specified functions and their relationships are properly performed. For example, the metering module functions may be divided between several systems, or at least partially performed by the overall control system.

[0085] The above description includes examples of one or more embodiments. Of course, for the purpose of describing the aforementioned embodiments, it is not possible to describe every possible combination of components or methods, but those of ordinary skill in the art will recognize that many further combinations and permutations of various embodiments are possible. Therefore, the described embodiments are intended to cover all such changes, modifications and variations that fall within the spirit and scope of the appended claims. In addition, in the sense of using the term "includes" in the detailed description or claims, such term is intended to be included in a manner similar to the term "comprising" because "comprising" is interpreted as a transitional word in the claims when adopted. In addition, although the elements of the described aspects and / or embodiments may be described or required in the singular, the plural form may be expected unless a limitation to the singular is explicitly stated. Additionally, unless otherwise stated, all or part of any aspect and / or embodiment may be utilized together with all or part of any other aspect and / or embodiment.

Claims

1. A method for roughening the surface of a fixture in a semiconductor lithography apparatus, the method comprising the following steps: loading a roughened substrate onto a stage, the roughened substrate having a surface provided with a plurality of abrasive elements; aligning the roughened substrate with the fixture so that the surface of the fixture having the burls is opposite the face of the roughened substrate having the abrasive elements; pressing the abrasive element against the surface of the fixture; roughening the burl by substantially translating the abrasive element in a plane substantially parallel to the surface of the fixture until a desired roughness is achieved; removing the roughened substrate from the fixture; moving the roughened substrate to a position where the roughened mask can be unloaded from the stage; as well as The roughened substrate is unloaded from the stage.

2. The method of claim 1 , wherein the step of translating the roughened substrate in a plane substantially parallel to the surface of the fixture until a desired roughness is obtained comprises: It is determined when the burl has the desired roughness.

3. The method of claim 2, wherein determining when the desired roughness has been achieved comprises: It is determined when an amount of time has elapsed that is known to result in the desired roughness.

4. The method of claim 2, wherein determining when the desired roughness has been achieved comprises: The roughness of the burl is sensed.

5. The method of claim 1 , wherein roughening the burl by substantially translating the abrasive element in a plane substantially parallel to the surface of the fixture until the desired roughness is achieved comprises: The substrate is moved.

6. The method of claim 1 , wherein a plurality of abrasive elements are mechanically coupled to respective actuators, and wherein roughening the burls by substantially translating the abrasive elements in a plane substantially parallel to the surface of the fixture until the desired roughness is achieved comprises: The actuator is caused to substantially move its corresponding abrasive element in a plane substantially parallel to the surface of the fixture. The method of claim 6 , wherein the actuator comprises a piezoelectric element.

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