JP3713479B2 - Flat projection apparatus and element manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention
A radiation system for supplying a projection beam of radiation;
A support structure that supports patterning means that serves to pattern the projection beam according to a desired pattern;
-A vacuum chamber providing a vacuum beam path for the projection beam;
A substrate table for holding the substrate;
A projection system comprising a projection system for projecting a patterned beam onto a target portion of a substrate.
[0002]
[Prior art]
As used herein, the term “patterning means” refers to means that can be used to impart a patterned cross-section corresponding to the pattern to be formed in the target portion of the substrate to the incoming radiation beam. The term “light valve” can also be used in this context. In general, the pattern corresponds to a particular functional layer in a device being formed in the target portion, such as an integrated circuit or other device (see below). Examples of such patterning means include:
-Mask. The mask concept is well known in lithographic technology and includes mask types such as binary, alternating phase shift, and attenuated phase shift, as well as various hybrid mask types. By positioning such a mask in the radiation beam, radiation that impinges on the mask is selectively transmitted (in the case of a transmissive mask) and reflected (in the case of a reflective mask) according to the pattern of the mask. In the case of a mask, the support structure is generally a mask table, which can reliably hold the mask in a desired position in the incoming radiation beam and can move relative to the beam as desired. enable.
A programmable mirror array. An example of such an element is a matrix-addressable surface having a viscoelastic control layer and a reflective surface. The basic principle behind such devices is (for example) that the addressed area of the reflective surface reflects incident light as diffracted light, while the unaddressed area reflects incident light as non-diffracted light. By using a suitable filter, the undiffracted light can be filtered from the reflected beam, leaving only the diffracted light. In this way, the beam becomes patterned according to the address pattern of the matrix addressable surface. The required matrix addressing can be performed using suitable electronic means. Further information regarding such mirror arrays can be gathered, for example, from US Pat. Nos. 5,296,891 and 5,523,193, which are hereby incorporated by reference. In the case of a programmable mirror array, the support structure may be implemented, for example, as a frame or table that may be fixed or movable as required.
-Programmable LCD array. An example of such a structure is provided in US Pat. No. 5,229,872, which is included herein for reference. As described above, the support structure in this case may be implemented as, for example, a frame or a table that can be fixed or movable as required.
For the sake of clarity, the remainder of this description may specifically refer to examples including masks and mask tables at certain points. However, the general principles discussed in such cases should be understood in connection with the broad patterning means as described above.
[0003]
For example, a flat projection apparatus can be used in the manufacture of integrated circuits (ICs). In such a case, the patterning means generates a circuit pattern corresponding to the individual layers of the IC, which pattern (for example 1) of the substrate (silicon wafer) coated with a layer of radiation-sensitive material (resist). It can be imaged on a target portion (consisting of more than one die). In general, a single wafer will contain a whole network of adjacent target portions that are successively projected via the projection system, one at a time. In current devices that employ patterning with a mask on a mask table, a distinction can be made between two types of machines. In one type of flat projection apparatus, each target portion is irradiated by exposing the entire mask pattern on the target portion in one operation. Such an apparatus is commonly referred to as a wafer stepper. In an alternative apparatus commonly referred to as a step-and-scan apparatus, each target portion gradually scans the mask pattern under the projection beam in a predetermined reference direction (“scan” direction), while Irradiation is performed by synchronously scanning a substrate table parallel or antiparallel to the direction. In general, since the projection system has a magnification factor M (generally <1), the speed V at which the substrate table is scanned is a factor of M times the speed at which the mask table is scanned. Further information regarding the lithographic printing apparatus described herein can be gathered from US Pat. No. 6,046,792, which is included herein for reference.
[0004]
In a manufacturing process using a flat projection apparatus, a pattern (eg in a mask) is imaged on a substrate that is at least partially covered by a layer of radiation-sensitive material (resist). Prior to this imaging step, the substrate may be subjected to various processes such as priming, resist coating and soft baking. After exposure, the substrate may be subjected to other processes such as post-exposure bake (PEB), development, hard bake and measurement / inspection of the imaged formation. Such an alignment process is used as a reference for patterning individual layers of elements such as ICs. Such patterned layers can then be processed through various processes to finish all individual layers, such as etching, ion implantation (doping), metallization, oxidation, chemical-mechanical polishing, and the like. That's fine. If several layers are required, the entire procedure, or a variation thereof, must be repeated for each new layer. Eventually, an array of elements is formed on the substrate (wafer). These elements are then separated from each other by techniques such as dicing or sawing, after which the individual elements can then be mounted on a carrier connected to pins or the like. Further information on such methods is included by reference, by Peter Van Zant, published by McGraw Hill Publishers, 1997 ISBN 0-07-0667250-4, which is incorporated herein by reference. It can be gathered from a book named “Microchip Fabrication: A Practical Guide to Semiconductor Processing” (Microchip Fabrication: A Practical Guide to Semiconductor Processing).
[0005]
For clarity, the projection system may be referred to hereinafter as a “lens”, but the term is intended to cover various types of projection systems including, for example, refractive optical devices, reflective optical devices, and catadioptric optical devices. It should be interpreted broadly. The radiation system also includes elements that operate according to any of these design types for directing, shaping, or controlling the projection beam of radiation, such elements may also be aggregated or separately: Sometimes referred to as “lens”. Further, the flat plate apparatus may be of a type having two or more substrate tables (and / or two or more mask tables). In such a “multi-stage” device, additional tables can be used in parallel, or a preparatory step can be performed on one or more tables while one or more tables are being used for exposure. . For example, US Pat. No. 5,969,441 and International Patent No. WO 98/40791, which are hereby incorporated by reference, describe a dual stage flat plate apparatus.
[0006]
In such a flat plate apparatus, it is typically necessary to provide areas in the apparatus having different atmospheric pressures, for example, one area is atmospheric pressure and the other area is vacuum. However, it can move freely, but it is necessary to provide an element in the device that separates the regions of different pressures. Accordingly, there is a need to provide a device having a bearing that allows movement of the element and a vacuum seal that maintains a differential pressure between regions separated by the movable element.
[0007]
In the accompanying drawings, FIG. 2 (a) schematically illustrates such a vacuum sealed gas bearing assembly. It consists of a slider 10 that separates a gas (gas) region at atmospheric pressure from a vacuum chamber 12 containing a vacuum. A gas bearing 14 is provided at the boundary between the slider 10 and the vacuum chamber 12. The bearing comprises one or more holes or grooves from which gas is pumped to support the slider 10 and provide a cushion of gas that allows the slider to move with very little friction. sell. The holes or grooves from which the gas is pumped can be separated by lands in which the gas is pressurized. The movement of the slider 10 can be brought about by means (not shown) such as an electromagnetic actuator or motor.
[0008]
A differential pressure seal 16 is also provided at the boundary between the slider 10 and the vacuum chamber 12. The differential pressure seal 16 consists of one or more series of grooves or holes through which gas is drawn by a vacuum pump. Therefore, the gas discharged by the gas bearing 14 and moving in the direction toward the vacuum inside the vacuum chamber 12 is swept by the differential pressure seal 16.
[0009]
More details regarding vacuum sealed gas bearing assemblies are described, for example, in US Pat. No. 4,191,385, which is hereby incorporated by reference.
[0010]
One problem associated with such an assembly is that, as shown in FIG. 2B, the atmospheric pressure outside the vacuum space applies a force distributed over the entire top surface of the slider 10, but the slider 10 On the other side, there is no corresponding force applied by the vacuum, instead there is only a force in the gas bearing indicated by the large upward arrow in FIG. 2 (b). Thus, as a result of the force distribution, the slider 10 tends to deform due to the large bending inertia applied to it. However, since the precision requirements for the sliding surface in the gas bearing are high, deformation is not acceptable. In the figure, the gap between the sliding surfaces is not shown to scale. In practice, it is very small and the surface must be flat and parallel with a high degree of tolerance. As a result, in conventional designs it is extremely rigid and therefore the slider 10 is very heavy to prevent any deformation of the sliding surface. As a result, there arises a problem that a large force is required to displace the heavy slider 10 for that purpose.
[0011]
When a gas bearing assembly such as that described above is used in a flat plate apparatus to support the sliders that make up the substrate table or mask table, these tables need to move very quickly and very frequently. The need to accelerate results in the problem of requiring a great deal of force due to weight design and heavy mass, which means a great loss of power in the device.
[0012]
[Problems to be solved by the invention]
The present invention aims to at least partially alleviate the aforementioned problems.
[0013]
[Means for Solving the Problems]
This and other objects are in accordance with the invention a flat projection apparatus as described in the opening section of the specification,
A movable member supported by a gas bearing in use, having movable first and second sides opposite to each other, the second member being exposed to the interior of the vacuum chamber;
A pressure correction vessel provided on the first side of the movable member to provide a substantially uniform gas pressure over at least a portion of the first and second sides of the movable member; This is achieved by a flat plate projection apparatus.
[0014]
By providing a substantially uniform gas pressure over at least a portion of the first and second sides of the movable member, it is possible to significantly reduce the bending inertia with respect to the movable member, thereby reducing the rigidity of the movable member. It is possible to maintain the tolerance on the sliding surface of the gas bearing that is still necessary to allow satisfactory operation while lowering and reducing weight. For example, the pressure on one side may be a rough vacuum and the pressure on the other side may be an ultra-high vacuum, but both pressures are basically zero for atmospheric pressure. It can be determined relative to atmospheric pressure, such as pressure.
[0015]
It is preferable that the inside of the pressure correction container communicates with a region on the second side of the movable member by a passage. This allows pressure uniformity to be easily and passively achieved without the need for any additional equipment, pumps, pressure gauging, etc.
[0016]
The pressure correction container is preferably at least partially deformable. This can reduce the weight of the container.
[0017]
It is preferable that at least one wall of the pressure correction container is in contact with the movable member in the vicinity of a region where the movable member is supported by the gas bearing in use. This means that the force applied to the movable member by the external pressure on the pressure compensation vessel is generally in harmony with the force applied to the movable member by the gas bearing, and thus the torque or bending inertia on the movable member is generally minimized. To do.
[0018]
It is preferable that a hollow member is provided on the second side of the movable member, and an opening is provided from the hollow member through the movable member and the pressure correction container. This means that, for example, air can be taken into a movable member such as a slider, and the cable can be led out from the slider. It is preferable to provide a bellows around the opening in order to block the inside of the pressure correction container from the inside of the hollow member. The bellows provides a barrier that allows the inside of the pressure compensation vessel to be kept at a different pressure than the inside of the hollow member, and because it is a bellows, the pressure compensation vessel is still deformable, and importantly, the bellows Since it is deformed, no force is applied to the movable member. In this way, the deformation of the pressure correction container is separated from the movable member by the bellows, and hence the deformation of the sliding surface is eliminated.
[0019]
The movable member may be a slider that allows displacement for xy coordinate positioning of the substrate table or mask table, or the movable member may perform rotational positioning about a specific axis, or combine both linear sliding and rotation It can be a rotor that can.
[0020]
The gas pressure in the pressure correction vessel and on the second side of the movable member in the vacuum chamber is preferably lower than atmospheric pressure, more preferably the pressure is 100 Pa or less, or actually several times more than this, ie many Double lower, eg 10^-2  Pa (10^-Four  Mbar) or less, preferably vacuum or ultra-high vacuum.
[0021]
According to another aspect of the invention,
Providing a substrate at least partially covered by a layer of radiation sensitive material;
Providing a projection beam of radiation using a radiation system;
Providing a vacuum beam path for the projection beam in the vacuum chamber;
Applying a pattern to the cross section of the projection beam using patterning means;
Projecting a patterned beam of radiation onto a target portion of a layer of radiation-sensitive material, comprising:
Providing a movable member supported by a gas bearing, the movable member having first and second sides opposite to each other, the second side being exposed to the inside of the vacuum chamber; Providing a pressure correction vessel on a first side of the member; and substantially equalizing gas pressures on at least a portion of the first side of the movable member and the second side of the movable member. An element manufacturing method is provided.
[0022]
Although particular reference is made herein to the use of the device according to the invention in the manufacture of ICs, it should be clearly understood that such a device has numerous other applications. For example, the apparatus according to the invention can be employed in the manufacture of integrated optical systems, guide and detection patterns for magnetic domain memories, liquid crystal display panels, thin film magnetic heads, and the like. One skilled in the art will recognize that the terms “reticle”, “wafer”, or “die” as used herein in connection with such alternative applications are the more universal “mask”, “substrate”, and Recognize that the term “target part” should be considered instead.
[0023]
As used herein, all types of electromagnetic radiation, including ultraviolet light (eg, wavelengths 365, 248, 193, 157, and 126 nm) and EUV (eg, far ultraviolet light in the range of 5-20 nm), as well as, for example, ion beams Or the terms “radiation” and “beam” are used to cover particle beams such as electron beams.
[0024]
Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings.
[0025]
In the figure, corresponding reference symbols indicate corresponding parts.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
FIG. 1 schematically illustrates a flat projection apparatus according to the present invention. The apparatus includes:
A radiation system LA, IL for supplying a projection beam PB of radiation (eg UV or EUV radiation, electrons or ions);
A first object having a first object (mask) holder for holding a mask MA (for example, a reticle) and connected to the first positioning means PM so as to accurately position the mask with respect to the object PL Table (mask table) MT.
A second object (substrate) holder that holds the substrate W2 (for example, a resist-coated silicon wafer) is connected to the second positioning means P2W in order to accurately position the substrate with respect to the object PL. A second object table (substrate table) W2T;
A third object table (substrate table) that includes a third object (substrate) holder that holds the substrate W3 (for example, a silicon wafer coated with a resist) and that accurately positions the substrate with respect to the object PL. W3T;
A projection system (“lens”) PL (eg, a refractive or catadioptric lens system, a mirror group, or an array of field deflectors) that images the irradiated portion of the mask MA onto a target portion C of the substrate W.
[0027]
The radiation system is a light source LA that generates a beam of radiation (eg, an undulator or wiggler provided around an electron beam path in a storage ring or synchrotron, a plasma source, an electron or ion source, a mercury lamp or a laser. )including. The beam traverses various engineering elements included in the illumination system IL, so that the resulting beam PB has a desired shape and intensity distribution in cross section.
[0028]
The beam PB then impinges on the mask MA held by the mask holder on the mask table MT. Since it is selectively reflected (or transmitted) by the mask MA, the beam PB passes through the “lens” PL, which focuses the beam PB on the target portion C of the substrates W2 and W3. With the help of the positioning means P2W, P3W and the interference dislocation measuring means IF, the substrate tables W2T, W3T can be moved precisely to position the various target portions C in the path of the beam PB, for example. Similarly, the positioning means PM and the interferometric dislocation measuring means IF are used to accurately position the mask MA with respect to the path of the beam PB, for example after the mask MA has been mechanically retrieved from the mask library or during the scanning movement. Can be used for In the prior art, the movement of the object tables MT, W2T is generally realized with the aid of a long stroke module (coarse positioning) and a short stroke module (fine positioning) which are not clearly shown in FIG.
[0029]
The illustrated apparatus can be used in two different modes. That is,
In step mode, the mask table MT is basically kept stationary and the entire image of the mask is projected onto the target portion C in a single operation (ie, a single “flash”). The substrate table W2T is then shifted in the X and / or Y direction so that a different target portion C can be illuminated by the beam PB.
In scan mode, basically the same procedure is applied, except that a given target portion C is not exposed with a single “flash”. Instead, the mask table MT is movable at a velocity v in a predetermined direction (so-called “scan direction”, eg Y direction), so that the projection beam PB is scanned over the image of the mask and at the same time the substrate table W2T. Move in the same direction or in the opposite direction at a velocity V = Mv. M is the magnification of the lens PL (for example, M = 1/4 or 1/5). In this way, it is possible to expose a relatively large target portion C without having to compromise on resolution.
[0030]
In the flat projection apparatus according to the present invention, at least one of the first and second object tables is provided in the vacuum chamber 8 schematically shown in FIG.
[0031]
Referring to FIG. 3A, a slider arrangement used to move the mask table MT or substrate table W2T, W3T of the above-described embodiment of the present invention is schematically shown in cross-sectional view. Since members corresponding to those shown in FIG. 2A are indicated by corresponding reference symbols, the description thereof will not be repeated. The apparatus includes a movable member, in this case a slider 10. There is a pressure correction container 20 on the first side 22 of the slider 10, and a gas (gas) such as air or a purge gas, which may be at almost atmospheric pressure, exists outside the pressure correction container 20. Below the slider 10, on the second side, there is a vacuum space containing the decompressed gas. The slider 10 is supported by an air bearing 14, and the differential pressure between the vacuum space and the external gas is held by the differential pressure seal 16 as described above with reference to FIG. 2 (a). Has been.
[0032]
A passage 26 is provided through the slider 10 so that the interior of the pressure correction vessel 20 communicates with the vacuum space in the region of the second side 24 of the slider 10. When the pressure balance is reached, the pressure inside the pressure correction vessel 20 becomes the same as the pressure in the vacuum space, and thus also becomes a vacuum. The inside of the pressure correction vessel 20 may be evacuated under reduced pressure by an independent gas discharge means without necessarily providing the passage 26. This is advantageous because any contaminants present in the pressure correction vessel 20 due to outgassing do not reach a highly contaminant sensitive vacuum space on the second side 24 of the slider 10. By any of the methods described above, the gas pressures at the main portions of the first side 22 and the second side 24 of the slider 10 are the same, so there is no significant bending inertia with respect to the slider 10, so that the slider has a high altitude. The rigidity of is not necessary and can be made lighter. Of course, external gas pressure is still present in the upper portion of the apparatus, but the upper wall 28 of the pressure correction vessel transmits the resulting force to the side wall 30 of the pressure correction vessel 20. Thus, instead of distributing pressure across the first side 22 of the slider 10, the pressure concentrates on the slider where the slider 10 contacts the sidewall 30. The side walls 30 are positioned so that they correspond to the position of the gas bearing 14. As a result, as shown in FIG. 3 (b), the force applied to the slider 10 by the side wall 30 indicated by a large downward arrow in FIG. 3 (b) is a gas bearing indicated by an upward arrow in FIG. 3 (b). In harmony with the force on the slider 10 from 14.
[0033]
In use, the upward force of the air bearing 14 needs to react not only to atmospheric pressure on the upper portion of the apparatus, but also to the weight of the slider 10 and related elements. Since the weight of the slider 10 resulting from the action of force due to gravity is of course distributed across the slider 10, there is still some bending inertia acting on the slider 10, which is inherent to the device, Although it is impossible to eliminate, the slider 10 acts on its upper surface 10⁵Since it is not deformed by the gas pressure of Pa, it is reduced from the fact that the slider 10 can be made lighter.
[0034]
  As shown in FIG. 3A, the upper side wall 28 of the pressure correction container 20 is inward due to an external gas pressure acting on the upper side wall 28 that is not corrected due to a vacuum inside the pressure correction container 20. It is shown as deformable due to the fact that it becomes a bow. The pressure correction container 20 can be partially deformed.PressureThis is advantageous in reducing the rigidity of the force correction container 20 and making it more lightweight. The key point of the pressure correction container 20 is that it changes the distribution of force due to gas pressure across the slider 10 so that they are not distributed over the entire first surface 22 of the slider, but instead of the pressure correction container 20. It is to be transmitted through the side wall 30.
[0035]
Example 2
Another preferred embodiment of the present invention is shown in FIG. Only features that are different from FIG. 3A will be described. In the drawings so far, the slider 10 has been schematically illustrated as a simple beam, but in practice a more desirable shape is shown in FIG. 4, in which air or other gas is taken inside the slider. A hollow member is provided on the lower side of the slider 10 for obtaining. An opening 34 is provided through the slider 10 and through the upper side wall 32 of the pressure correction container 20 to lead out a cable or the like from the inside of the hollow member 32. Gas tight around the opening 34 to seal the internal vacuum of the pressure correction vessel 20 from the external atmosphere that can pass through the opening 34 into the interior of the hollow member 32 with any desired cable (not shown). A bellows 36 is provided. Bellow 36 is made of metal or other suitable material and is in the form of a concertina. Since the bellows 36 is swayable, the upper side wall 28 of the pressure correction container can be deformed. However, since the elasticity of the bellows 36 is zero or extremely small, no force is actually transmitted to the first side 10 of the slider 10 when compressed in the vertical direction. In this manner, the upper wall 28 of the pressure correction container 20 can be deformed without transmitting force to the slider 10 at a point far from the support point provided by the air bearing 14 and can be lightweight. . Most of the force generated from atmospheric pressure at the upper side wall 28 of the pressure correction vessel 20 is still transmitted through the side wall 30 located in alignment with the air bearing 14. There is a small additional force on the slider 10 equal to the area of the opening 34 multiplied by atmospheric pressure, but this force acts on the slider 10 where the wall of the hollow member 32 is joined to the slider. Still, it is much smaller than the overall force of the gas pressure on the upper wall 28 of the pressure correction vessel 20.
[0036]
While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The above description is not intended to limit the invention.
[Brief description of the drawings]
FIG. 1 shows a flat projection apparatus according to an embodiment of the present invention.
FIG. 2 (a) shows a schematic cross-sectional view of a slide and its supporting device.
FIG. 2 (b) schematically illustrates the force on the slider shown in FIG. 2 (a).
FIG. 3 (a) schematically illustrates a cross section of a slider device embodying the present invention.
FIG. 3 (b) schematically illustrates the force shown in FIG. 3 (a).
FIG. 4 schematically illustrates in cross-section another embodiment of a slider device according to the present invention.
[Explanation of symbols]
C Target part
IL radiation system
IF interference dislocation measurement means
LA radiation source
MA mask
MT mask table
PB projection beam
PL lens
PM positioning means
W substrate
WT board table
10 Slider
12 Vacuum chamber
14 Air bearing
16 Differential pressure seal
20 Pressure compensation container
22 First side of slider
24 Second side of slider
26 Passage
28 Upper wall of pressure compensation container
30 side walls
32 Hollow member
34 Opening
36 Bellows

Claims (11)

A radiation system providing a projection beam of radiation;
A support structure that supports patterning means that serves to pattern the projection beam according to a desired pattern;
-A vacuum chamber providing a vacuum beam path for the projection beam;
A substrate table for holding the substrate;
A projection system comprising a projection system for projecting a patterned beam onto a target portion of the substrate, further comprising:
A movable member supported by a gas bearing in use, the movable member having first and second sides opposite to each other, the second side being exposed to the inside of the vacuum chamber;
A pressure correction vessel provided on the first side of the movable member and at least partially deformable, the interior of the pressure correction vessel communicating with the second side of the movable member via a passage A flat plate projection apparatus. A radiation system providing a projection beam of radiation;
A support structure that supports patterning means that serves to pattern the projection beam according to a desired pattern;
-A vacuum chamber providing a vacuum beam path for the projection beam;
A substrate table for holding the substrate;
A projection system comprising a projection system for projecting a patterned beam onto a target portion of the substrate, further comprising:
A movable member supported by a gas bearing in use, the movable member having first and second sides opposite to each other, the second side being exposed to the inside of the vacuum chamber;
A flat plate projection apparatus comprising: a pressure correction container provided on the first side of the movable member and at least partially deformable , wherein a gas pressure in the pressure correction container is lower than an atmospheric pressure;   The apparatus according to claim 1 or 2, wherein a gas pressure in the pressure correction container is 100 Pa or less.   The apparatus according to claim 1 or 2, wherein a gas pressure in the pressure correction container is 0.01 Pa or less.   5. The device according to claim 1, comprising two regions separated by the movable member and the pressure correction container and having different gas pressures, wherein one of the regions includes a region formed from the inside of a vacuum chamber. The device described in 1.   6. The apparatus of claim 5, including a differential pressure seal for maintaining different gas pressures in the two regions while allowing the movable member to be movably supported by the gas bearing. The at least one wall of the pressure correction container is in contact with the movable member in the vicinity of a region where the movable member is supported by the gas bearing in use. The device according to item. The hollow member is provided in the 2nd side of the said movable member, The opening which passes the said movable member and the said pressure correction container from the inside of the said hollow member is provided in any one of Claim 1-7 The device described in 1. The apparatus according to claim 8, wherein a bellows is provided around the opening to block the inside of the pressure correction container from the inside of the hollow member. The apparatus according to any one of claims 1 to 9, wherein a gas pressure on the second side of the movable member is lower than an atmospheric pressure. Providing a substrate at least partially covered by a radiation sensitive layer;
Providing a projection beam of radiation using a radiation system;
Providing a vacuum beam path for the projection beam in the vacuum chamber;
Using a patterning means to impart a pattern in the cross section of the projection beam; ,
Projecting a patterned beam of radiation onto a target portion of a layer of radiation sensitive material, comprising:
Providing a movable member supported by a gas bearing, having opposite first and second sides, wherein the second side is exposed to the interior of the vacuum chamber; and at least a portion Providing a pressure correction container that is deformable on the first side of the movable member, the gas pressure in the pressure correction container on the first side of the movable member, and the second side of the movable member And substantially equalizing the gas pressure over at least a portion of the device.

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