JP5866323B2 - Lithography system, clamping method and wafer table - Google Patents

Description

  The present invention relates to a lithography system for projecting an image pattern onto a target surface such as a wafer.

  Such a system is generally known, for example, from WO2004038509. In the example proposed by the latter system, the target to be patterned is irradiated with photons or charged particles such as ions or electrons. In order to achieve high-precision patterning of the target, at least if the target position measurement is made by the target table, the target is firmly adhered to the target table so that it is moved relative to the incident source, or Should be connected. Such movement is at least in a predetermined direction essentially transverse to the main direction of incidence. Also, the target remains in a predetermined position relative to the table during processing of the target, for example, during insertion and removal of the target to and from the processed position, and the relative position of the target and the table. Can be measured as the final processed part. Furthermore, such requirements should remain valid where insertion and removal are made to and from the vacuum environment. There are various solutions that meet the above requirements, for example by electromechanical clamping.

  At locations where a target, typically a wafer, is processed in modern lithography systems is typically a chuck or wafer table, where instead there is a target transport means shown as a reference to the target. Such a reference, i.e. a transport means, is formed fairly flat to support positioning and minimizing focus errors during lithographic exposure of the target. For this purpose, in particular to avoid or prevent the occurrence of bows and warps here, the target is at least in close contact with the reference by exerting a force on it during the exposure. Maintained. In this way, the target is optimally maintained within the depth of focus of the lithography system in which the target is included. Generally, the force is obtained as a pulling force and is generated by electrostatic or vacuum means acting on the target.

  However, such a solution may have drawbacks with respect to the transport tube, cable and table wiring, so that the required accuracy of the table relative to the projection means of the litho system is required. Increases the complexity of positioning. Also, systems where the target is integral with the target table where the target is removed have the disadvantage that connection and disconnection operations are required, followed by cable cabling, writing, and conduits.

  A further important requirement for a lithography system for patterning a target includes the need for achieving planarization of the target, i.e., eliminating the curvature and warpage of the wafer made by pulling the target for reference. Means for performing this function are usually the same as or limited to those performing the function of maintaining the target at a predetermined position on the table within the exposure field.

  Means for maintaining the target in place and pulling the target on a flat reference may be loaded by thermal expansion and contraction due to the energy loading of the projection system of the system, such as included in the patterning of the wafer. .

  Thus, a further requirement for known lithographic systems is to achieve heat conduction between the target and the target table so that heat is actually conducted from the target towards the heat dissipation portion of the system. Such rapid conduction and dissipation of heat limits positioning distortion due to thermal expansion or contraction of the target. The latter is particularly important in modern lithography systems seeking to achieve high throughput, particularly for wafers per hour, where the target is subjected to a relatively high energy load and is usually transferred to heat. If not handled in this way, it can cause distortion of the positioning.

  Where heat dissipation can be handled by heat dissipation means, the transport of heat directed to the target towards this heat dissipation means is still a limiting factor in any solution for heat dissipation. obtain. Therefore, a further object of the present invention is to provide a clamping method which, while practical at the time of use, performs at least the positioning function of the table or chuck carrying the target without any distortion and optimally addresses the problem of heat conduction. And realizing the clamping means.

  In general, the positioning of a target, such as a wafer on a chuck, is known by machining processes such as EP0100648, JP7237066 and JP8066462, in which the wafer is frozen on the chuck before machining the wafer. Is done. To summarize the latter publication, the wafer is mounted on the wafer mounting surface by a layer of pure water having a microscale thickness. A drawback with the positioning accuracy required when transferring these known concepts to the lithography system is the pipe installation required to provide cooling by the chuck.

  The above disadvantages are illustrated in PCT / US01 / 26772 which discloses wafer clamps in lithography systems. The clamp is also used for the transport of heat induced by the charged particle beam on the target. Clamping and release of the target is accomplished in this apparatus by providing “at least one” phase transition to the clamping element provided between the wafer and the support structure. These phase transitions “facilitate various operations during processing” and “ensure that the wafer can be easily loaded and released from the structure”. The clamping element is provided in liquid or gaseous form and is brought to a solid state by vigorous cooling of the support structure so as to effect a firm clamp of the wafer to the structure. Here it is concluded that such a clamping method can basically mean bonding the wafers.

  The known clamping devices described above for lithographic systems, especially in vacuum due to the large contact area between the component and the wafer, and in the high thermal conductivity of the clamping element, “in processes requiring cooling of the wafer” It is shown to be particularly useful. However, the disadvantages of this known system are the multiple conduits required to transport the clamping elements separately and the circulating cooling fluid to the target table in addition to the temperature changes required for the support structure. .

  US Patent Publication No. 2005/0186517 relates to a process for a lithography system in which a wafer is attached to a chuck that aligns the wafer to a wafer stage and subsequently exposed. In particular, this document teaches that after the initial stress that reduces the expansion of the wafer chuck, it causes an opposite stress to the expansion of the wafer, potentially resulting in a gap between the wafer and the chuck. Double the allowable heating of the wafer before undesired slips appear. The attachment process is illustrated by a process using an electrostatic clamp and by a process using a vacuum clamp, and requires the installation of cables and conduits to a movable table carrying the target.

Outside the vacuum environment faced in the field of lithographic exposure of the target, in the technical field of wafer testing, the 1991 en of the presentation "Liquid Interface in Wafer Testing" presented at the SWTW 2005 Conference on June 4, 2005 EP patent application 511928 is known, according to which the integration of heat conduction and clamping of the wafer to the chuck by a water flow film is known. The principle envisaged in this known device is to achieve heat conduction induced in the target by the film of water by maintaining the target at a fairly thin thickness, but usually on the back side of the wafer. It is large enough to flatten the roughness you face. In this principle according to the first document, the clamping is realized by the transfer of fluid to the upper side of the chuck's grooved flat clamping section.

  In the latter document, it appears that the groove appears to be removed from the clamp section, and heat is not transported by the fluid flow, and this explanation is made by noting that “the fluid is conducted to the chuck”. Support implicitly. Furthermore, it shows that the wafer has been pulled firmly onto the film by the vacuum, which is at the chuck recovery position, around the wafer positioned on the chuck, and into the liquid film between the chuck and the wafer. Given, thus, the fluid enters through the central opening.

  Due to the vacuum conditions in which lithography systems are made in modern systems, it is impractical to do this concept in the field of wafer testing against wafer exposure fields. However, a disadvantage to lithography systems that are not made under severe vacuum conditions can also be a generally undesirable phenomenon, especially due to the risk of water clogging with water, especially due to contamination. In the case of the required vacuum operation, the known system fails due to the lack of overpressure on the upper side of the target. Where the recovery opening requires a certain amount of vacuum, ie where the pressure is below atmospheric pressure to cause fluid flow, the central supply opening for fluid assumes a higher pressure than on the recovery side. . The system should be placed in a vacuum environment and the target tends to be lifted rather than tend to be clamped.

International Publication No. 2004/038509 European Patent No. 0100168 Japanese Patent No. 7237066 Japanese Patent No. 8064662 International Patent Application PCT / US01 / 26772 US Patent Publication No. 2005/0186517 European Patent Application No. 511928

Publication of presentation presented at SWTW2005 meeting on June 4, 2005 "Liquid interface in wafer test"

The present invention seeks to realize a clamping system for modern lithography systems, i.e., a clamping system that provides a relatively high accuracy pixel resolution and a relatively accurate accuracy of target and source relative positioning. The limitations here include a system capable of operating a vacuum from the exposed target to the target transport means, i.e. the chuck, and optimal heating conditions. To achieve this, the present invention provides a stationary liquid film contained between the transport means and the target so that both the heat transfer function and the clamping function are performed by the same liquid means. ), Suggesting the use of capillaries.

  With the new solution, the cables or conduits that lead from the “fixed” world to the mobile target vehicle are completely removed, so that these negative effects are not completely reduced, The conveying means is positioned fairly accurately.

  The present invention is surprisingly very general explained by the “Negative Pressure Physics” paper published in Discover on March 27, 2003, if the conditions for this were set appropriately. The terminology starts with the idea that a strong tensile force can be exerted on a liquid such as water. In the case of a lithography system, such a setting can be reached if the liquid is kept stationary as a capillary between the target surface of the wafer and the target transport means, i.e. the chuck. And these surfaces are usually kept as flat as possible for obvious reasons.

  In such capillaries containing liquid, in practice, the liquid volume between two plates or the liquid volume of one plate, the adhesion of the liquid to the surface of the plate, similar to that in current lithographic applications, is extended to the periphery. The surface of the plate extends concavely between the two plates. This concave liquid surface tends to maintain its shape, including that negative tension occurs with capillaries containing liquid deposits, even if tension is applied by pulling the plates apart.

  Furthermore, according to the present invention, with regard to including the capillary, it is realized that the liquid layer is so small that no boiling of the liquid, e.g. water, can occur, even when the liquid is under negative pressure. The This phenomenon is of practical value in heat conduction. Thus, it is believed that liquid at negative pressure can be applied to provide the force necessary to pull the target or wafer to a flat reference. In other words, the liquid in a small gap, such as between the plates formed by the reference and the target, exerts a force on the plates that make up the gap. Apart from the height of the gap, this force, which is dependent on the properties of the liquid and the material of these plates, is given in order to realize the force to maintain the integration of the target and the target table.

In such a new concept, the pressure inside the fluid is lower than zero, but it contains tension in the fluid and the height of the gap between the target and the reference is the bubble of the vapor at the pressure of the associated liquid. When made smaller than the critical radius of the liquid, it is realized that the liquid does not form bubbles, ie does not boil. Thus, also in this regard, in the case of including the described stationary capillary, boiling a liquid such as water when the liquid can generate a substantial clamping force sufficient for lithographic applications. It is realized that it is not possible.

  It will be apparent that the principles of the invention can be implemented in a variety of ways.

  The invention will be explained more clearly by means of the following embodiment example of a maskless lithography system according to the invention.

FIG. 1 is a cross-sectional view schematically showing a liquid capillary tube, structured as contained between two plates, namely the surfaces of materials A and B. FIG. FIG. 2 is a graph showing the relationship of capillary pressure drop to dissolved silica optical flat and silicon wafer with gap height between the capillaries of such plates containing water. FIG. 3 is a schematic diagram for implementing the idea underlying the present invention. FIG. 4 is a schematic diagram for implementing the idea underlying the present invention. FIG. 5 is a schematic diagram of a first method for incorporating liquid into the capillary gap between the table and the target. FIG. 6 schematically illustrates a technique for minimizing liquid evaporation from the capillary gap by providing a peripheral gutter. FIG. 7 schematically illustrates a method of providing a liquid layer between a target and a target table. FIG. 8 is a process flow of at least a portion of a lithography system according to the present invention. FIG. 9 is a schematic diagram of the use of a spacer.

  In the drawings, corresponding structural, ie at least functional, features are referenced by the same reference numerals.

  FIG. 1 shows a lithographic target, here in the form of a wafer 1. This wafer is typically moved by a driven target table or chuck, not shown in this figure, for example with respect to a charged particle beam column of a lithographic apparatus or other types of beam sources for lithography. To do. A predetermined volume of liquid 3 is contained in the capillary between the upper side of the target table 2 and the target 1. For this purpose, the target 1 and the top surface 2 have a mutual nominal distance of a gap height h. The volume of the liquid according to the invention, preferably water, is such that the radius of the target seen from above is substantially filled with the radius R of the capillary of the liquid 3 containing the liquid 3. In any case, the radius of the inscribed circle of the target is at least filled with the radius of the circumscribed circle suitable for the volume of liquid in the target boundary. In practice, the liquid stays within a target boundary, preferably only a short distance relative thereto. The liquid 3 thus contained forms a liquid surface 4 and instead means a fluid interface 4 at its outer periphery, as seen in the cross section according to FIG. And the adhesive connection of the liquid to each of the upper surfaces 2 of the target table has a substantially concave shape. This concave surface 4 tends to maintain this shape when pulled away from the target and the target table, which depends on the pressure difference. The dents in the interface 4 depend on the respective contact angles θ1 and θ2, and instead in this case depend on the material of the table 2 and the material of the target 1, which are material A and material B, respectively.

In FIG. 1, the capillary pressure ΔPcap is the pressure drop over the fluid interface 4 at the edge of the volume of the liquid 3. Capillary pressure can be defined by the following simplified equation, according to further insights underlying the present invention.

Here, γ liquid is the surface tension [N / m] of the liquid. The contact angles θ1 and θ2 are angles at which the liquid / vapor interface 4 is in contact with the materials A and B, respectively. However, these contact angles are particularly important if they are not determined predominantly by the material properties of the liquid 3 and the solid materials A and B at the location of the interface 4. For the same matter, the following equation is given.

By combining these equations (1) and (2), the following relationship can be understood.

The latter situation occurs when Penv is approximately 0 bar or when | ΔPcap | ≧ 1 bar below atmospheric pressure. This is because Plip <0 bar means that the pressure inside the liquid is negative. It is further recognized that if Pliq is less than the vapor pressure of the liquid, the liquid 3 may begin to boil or bubbles may begin to form. However, the boiling of the liquid 3 is prevented by forming a gap height that is smaller than the critical radius of the bubble.

FIG. 2 illustrates the capillary pressure drop. This is because, as described above, in the case of water, shows dark the magnitude of the force that can be exerted when separating the two plates, which may include a fluid. The curves shown are derived from calculations for two plates: the contacting surface and water. Here, one is a silicon wafer and the other is a melted silica optical flat. The validity of the curve was tested based on calculations and measurements on glass plates instead of SiO2. This curve compared to the case of glass and water shows that sufficient tensile force can be sufficiently achieved with a gap height of 10 μm or less nominally, even within a nominal height of 5 μm, reachable for normal lithographic applications Shows that it is enough. At this gap height, the pressure drop is greater than 1 bar, so a particularly interesting range is below a gap height of about 1 μm or less, and the negative pressure in the liquid in this gap already occurs at atmospheric pressure. However, a pressure drop already close to 0.2 bar occurs with a gap height of 10 μm, due to a clamp that ensures that the placed wafer, eg the wafer table, is safely processed where it is inserted into the vacuum. Enough.

  FIG. 3 schematically shows a practical description of the invented principle and a part of the lithography system. This includes a target 1 specifically indicated by the wafer, a wafer table 8 or upper side 2 of the chuck part, a liquid 3 in the form of water, a so-called Viton® or rubber O-ring 9. including. The O-ring 9 is inserted into a portion where the height of the rim of the wafer table 8 is lowered, thereby sealing the liquid vapor evaporating from the gap including the liquid 3. By this measurement, the upper side of the O-ring is set to a level corresponding to its height, preferably set slightly higher than the height of the burl 7 on the upper side of the wafer table 8. . On the radial side, in this example, a notch is provided on the radially inward side, and the O-ring is sufficiently long to prevent steam leakage without requiring excessive force. Between the wafer and the wafer. Such leakage is particularly problematic in a vacuum environment where such lithographic means can be utilized. Thus, in practice, the O-ring, which is here a predetermined thickness in the range of 0 to 5 mm in diameter, is in the form of a C-ring and the pressure required to press the O-ring is kept to a minimum. It means to be drunk. The radial distance is not shown here, but is high at the center of the O-ring and the target conveying means 8 to provide a plurality of openings such as a recovery opening for the fluid 3 provided therebetween. Held between the table parts. Preferably, an O-ring or similar type of elastically deformable means is provided at the periphery of the target. In this way, a relatively large force can be applied between the target and the elastically deformable means. This allows the use of elastically deformable means of relatively coarse roughness, such means being readily available and easy to handle and relatively economical at the time of purchase.

  Instead, as in FIG. 4, the leakage of vapor is caused by a plurality of protrusions 7 on the table by means of a vapor restriction ring 9A supported by the outer rim of the table that blocks most of the peripheral opening of the liquid gap. This is prevented by leaving a very slight vertical distance 9B between the supported ring 9A and the target 1. In particular, this can be 10 to 20 times smaller than the gap height between the target and the target table.

  In a further setup according to the invention, the principle is used that the liquid at pressures below the vapor pressure can be in a metastable state. Attention is paid to the critical radius of the cavity beyond which such cavities become unlimited. The smallest dimension of the deposit containing liquid, according to a preferred embodiment of the present invention, will be relatively very small or less than this critical radius and cavitation will not occur. When the pressure drop is due to Laplace-pressure, the critical radius is about twice the gap height or more. The height depends on the material properties (contact angle) between the liquid and the solid surface.

The present invention, it can be closed against the inlet of the fluid can be a gas, and the wafer table fluid can be opened is that for the release of at, thus, to free up the target from the table Can further include the presence of at least one aperture that is possible. A volumetrically very accurate fluid inlet tube is preferably provided in the center. In addition, the present invention includes a pressing means for first pressing the target so as to be in firm contact with the target table, that is, a plurality of protrusions 7 are provided thereon. One embodiment of such a pressing means includes a high pressure directed vertically towards the upper side of the target 1, thus eliminating any bending of the target and allowing capillarity to be incorporated. According to a further aspect of the invention, one preferred way to achieve such pressure is to direct a flow of fluid means such as wind or water over the target.

FIG. 5 illustrates one preferred method of operation. Here, instead, the chuck, ie the initial clamp, which means eliminating the curvature of the target, is removed. Also, the liquid is introduced between the target and the table in a more or less combined manner. For this purpose, a central inlet channel 10 is provided in the target table and a valve V is provided. The wafer is chucked to the wafer table by the vacuum force generated by the vacuum pressure Pvac provided by a plurality of openings 10B in the periphery. When the wafer is correctly chucked on the wafer table, the valve V is opened and liquid is sucked into the gap between the wafer and the wafer table. The filling rate of the water flowing into the gap is prevailing with the capillary pressure Pcap.
ng) determined by the sum of the pressure difference between the vacuum pressure Pvac and the overpressure Pop and is at or provided at the inlet of the channel 10, ie at a fluid source not shown. The overpressure Pop is defined to be higher than the pressure Penv that spreads over the target. This pressure is limited to 1 bar for practical reasons so as not to disturb the position of the target on the table. An effective hydraulic pressure Pliq is also calculated.

FIG. 6 shows a technique for preventing liquid evaporation from the capillary gap, i.e. between the target and the target table. In the target table, a gutter, that is, a gutter, is formed in a region where the periphery of the target 1 is sealed by the elastically deformable means 9 leaving the minimum gap 9B. This groove has a width much larger than the gap height of the capillary and is made to contain the liquid 3 'not contained in the capillary. Preferably, the fluid 3 ′ is the same type as the liquid 3 contained in the capillary. However, it is provided to have a fairly wide surface or interface area. This gutta, i.e. the groove, can be filled using a fluid source supplying a liquid at pressure P _op for the channel 10, but preferably by means of separate filling means, a reed and a valve. That is, it is provided independently of supplying a capillary containing liquid. The filling means can be any independent filling means, for example, a filling means including a separate liquid source, dedicated leads and valves to the gutter, and a fluid pump.

  FIG. 7 schematically illustrates an alternative method of incorporating the capillary layer. Rather than entering the fluid through a central opening as in the first embodiment example, here the fluid is either deposited on the droplet 11, for example by spraying, either on the table or on the target. Entered in one or both. Preferably, however, a part of the liquid that is evenly distributed is achieved, for example by placing the droplets by means of droplet dispersion, for example by having at least one droplet dispersion port in a predefined position. To be controlled. With such a deposition method, rapid dispersion of the liquid is achieved, thus increasing the feasibility of the new clamping method and means. In the current example, the droplets are deposited on the target table 8. In this embodiment, the various openings 12 to prevent the inclusion of air over the area of the target table, preferably in a generally defined manner to be evenly distributed. Distributed.

  Apart from the opening above, the surface of the target table is defined by the presence of a plurality of protrusions 7. These protrusions are for withstanding the clamping force of capillary liquids with high dispersion density. In this way, the attracted target can remain flat, i.e., will not bend between the protrusions under the force of the capillary fluid.

  In a particular measurement, one or both of the target and table contact surfaces, in particular towards the desired clamping pressure, in particular at the predetermined operating conditions, i.e. in vacuum, the liquid and its associated contact surface. Can be surface-treated or coated with a material to affect the contact angle between. In practice, given the current criteria for targets in the case of wafers, only the target table will be coated. In order to further influence the capillary pressure drop in the clamp according to the invention, the height of the protrusion is tailored to a specific, desired pressure drop, considering the liquid material, the target and the material of the surface in contact with the target table. It is possible. Matching in this way, for example, to match the minimum desired clamping force and to match a specific combination of clamping force, the distribution of multiple protrusions and mutual distance, in particular the clamping pressure and the resulting force on the target. In consideration, it can be done to prevent local curvature of the target between the plurality of protrusions. The minimum projection height is taken into account here in this way, and the density of the projections can be matched, for example increased to meet the minimum required clamping force. it is conceivable that. The minimum protrusion height is considered in connection with the measurement to accommodate dust or other contaminant particles between the protrusions and within the gap height. The latter, of course, cannot take place within the limits of the measurement according to the invention which maintains the gap height to thus minimize the boiling of the fluid between them.

FIG. 8 shows relevant portions of the process flow of a lithographic apparatus or system improved with the present invention. Here, the target is formed of a wafer. This processing part starts with a clean wafer table operation and state CT shown in the lower left corner. From here, either of two alternative processing paths can be made subsequently. The first, illustrated path portion includes a first process WOT that places the wafer on the target table, and a second process LIG that flows liquid through a conduit in the table into the gap between the table and the wafer. The third step CS is characterized by sealing the conduit for water, i.e. supplying liquid and removing contained air. A second possible path for performing the process according to the invention is indicated by the lower branch. This includes a first process LOT for applying a liquid on the table, a process WOT for placing the wafer on the table, and in this case simply a sealing process CS of the conduit comprising sealing off the contained air release, Is shown. Such sealing is preferably performed with a central discharge or supply conduit connected to the surface of the table by a plurality of branches.

  In the subsequent process IT, the table and wafer are inserted into the part of the lithographic system that is brought to a vacuum, the wafer is processed in process PW, the table and wafer are removed from the apparatus in process RT, and the wafer is Is removed from the table in step DW, in particular by removing or opening any conduit seals to clean the wafer table.

  In the case of a liquid application LIG, the water is provided by at least one conduit, but may alternatively be provided by multiple water conduits through which water is supplied to the gap. According to a further aspect of the invention, the filling of the gap is performed with a sufficiently large capillary pressure to allow water or any other associated liquid to be drawn into the gap. In a further embodiment, this process is improved, i.e. faster, by using an external pressure to increase the pressure during filling. However, in a further detail of the invention, an air-containing opening is used to supply a low pressure.

  In the case of a water application LOT on the table, the water application is accomplished by providing small, flat, evenly distributed droplets on the surface of the wafer table or wafer. When the wafer is placed on the wafer table, the droplets spread by capillary action. This process can be assisted by suction through a plurality of open holes. In the case of CS sealing the conduit, when the wafer table / wafer combination is in a vacuum, all the holes used for filling the gap are sealed after applying liquid to prevent evaporation. Must be stopped. In addition, when the wafer is removed from the table in the processing step DW, the opening used for supplying water or preventing air from being contained is also used for supplying air pressure. In further details of the invention, water is blown off the table. The air pressure is in this case distributed at least fairly evenly so that the wafer is not braked.

  Also, the smaller the gap, the greater the pressure drop required to keep the flow rate equal. Furthermore, such an increase in the required pressure drop is greater than the pressure increase from the capillary pressure resulting from the smaller gap. Therefore, the flow in capillary pressure is slower for smaller gaps, and in fact, gaps above the critical gap height given a given condition contain liquid material and contact surface material. At very small gaps, the electroviscous effect increases the apparent viscosity of the water, essentially known as “water capillary filling rate in the nanochannel”.

  Multiple protrusions are necessary to reduce the effects of contamination by particles on the backside of the wafer. The maximum pitch of these protrusions is determined by the distortion of the wafer between the protrusions caused by capillary pressure. A typical value of the pitch of these protrusions is 3 [mm]. The height of the protrusion is used to determine the gap and regulate the clamping pressure in view of other system conditions such as material and dimensions, and vice versa, in accordance with the present invention. The surface due to the protrusion is sufficiently formed so that it does not deform or become a brake under capillary pressure. The diameter of the protrusion is about 25 μm or more. These protrusions are preferably substantially round, i.e., have no corners, so as to reduce the possibility of contamination by particles during cleaning. These are particles from the tissue during table wiping.

In addition to or instead of using the protrusions 7, a plurality of spacers 15 (glass grains, SiO 2 grains, etc.) are sprayed, for example, over the conveying means 8 or a dispersion solution of these spacers By application, it is evenly distributed on the conveying means 8 as shown in FIG. 9, thus providing these spacers 15. In one embodiment, these spacers 15 are dispersed in the liquid 3 to ultimately form a layer of stationary liquid.

Apart from the concepts as described above and all the relevant details, the present invention is directly and clarified by those skilled in the art with all the features as defined in the following claims and the accompanying drawings. Related to all the details that can be derived. In the following claims, any reference signs corresponding to structures in the drawings shall not be construed as limiting the meaning of the terms described above, but to assist in interpreting the claims. It is simply given in parentheses to indicate its meaning.
The invention described in the scope of claims at the beginning of the filing of the present application will be appended.
[1] A lithography system for projecting an image or image pattern onto a target (1), the target being carried to the lithography system by a target table (2), the lithography system being placed on the table Clamping means for clamping the target is provided, the clamping means of the stationary liquid (3) in contact with the contact surfaces (A, B) between the contact surfaces (A, B) of the target and the target table. And a layer of the stationary liquid (3) is formed between the contact surfaces (A, B) such that the spacing between the target and the target table causes a capillary pressure drop (Pcap). The target table (2) includes a plurality of layers defining the thickness of the stationary liquid (3). System spacer (15) or projections (7) are provided.
[2] The system according to [1], wherein an interval between the target and the target table is 0.1 to 10 μm.
[3] The system according to [1] or [2], wherein a height of the spacer (15) or the protrusion (7) is equal to a distance between the target and the target table.
[4] The system according to any one of [1] to [3], wherein the capillary pressure drop results in a pressure (Pliq) that is lower than the vapor pressure of the layer of the stationary liquid (3).
[5] The lithography system according to any one of [1] to [4], which is used in a vacuum.
[6] The system according to any one of [1] to [5], wherein the thickness of the layer of the stationary liquid (3) is smaller than a critical radius of vapor bubbles of the stationary liquid (3).
[7] The system according to any one of [1] to [6], further comprising a peripheral sealing means provided between the target and the target table and sealing a periphery of the layer of the stationary liquid (3).
[8] The peripheral sealing means includes a vapor restricting ring (9A) disposed between the target table (8) and the target, and the vapor restricting ring (9A) includes the stationary liquid (3). The system of [7], which surrounds the layer with a gap.
[9] The steam restricting ring (9A) is disposed so as to leave a gap (9B) extending along a peripheral edge between the steam restricting ring and the target (1), and is also disposed on the target table. Is provided with a groove for containing a fluid, the groove having a width greater than the height of the gap (9B), and within the periphery defined by the steam restriction ring (9A), of the target table. The system according to [8], which is located on a periphery of the target support portion.
[10] The system according to any one of [1] to [9], wherein the target table is provided with a plurality of discharge openings that can be closed.
[11] The system according to [10], wherein the plurality of discharge openings are formed on a peripheral edge of the target table with a groove.
[12] The system according to any one of [1] to [11], wherein the liquid for clamping is water.
[13] The supply of the liquid between the target and the target table is performed by an application that spreads the liquid on one contact surface of the target table and the target. Or 1 system.
[14] The system according to any one of [1] to [13], wherein at least one of contact surfaces of the target and the target table is coated with a material different from a base of the contact surface.
[15] The system according to any one of [1] to [14], wherein the target table is formed without connection of a plurality of conduits in a lithographic apparatus for processing a target carried by the target table.
[16] The system according to any one of [1] to [15], wherein the target and the liquid layer are circular, and the volume of the liquid is such that the radius of the target is equal to the radius of the capillary tube containing the liquid. .
[17] A target table for inserting a target into a vacuum environment, comprising clamping means for clamping the target to the target table, the clamping means being a contact surface between the target and the target table (A, B) having a layer of stationary liquid (3) in contact with the contact surfaces (A, B), wherein the layer of stationary liquid (3) has an interval between the target and the target table. The target table (2) includes a layer thickness of the stationary liquid (3) included in the capillary formed between the contact surfaces (A, B) so as to generate a capillary pressure drop (Pcap). A table provided with a plurality of spacers (7, 15) for defining
[18] The clamping means realizes clamping outside the vacuum compartment of the lithographic apparatus before inserting the target table into the vacuum compartment of the lithographic apparatus to process a target carried by the target table. The table of [17] provided as follows.
[19] A method of clamping a target in a lithography system for projecting an image or image pattern onto a target (1) to a target table, said target being carried to this system by a target table (2) The system comprises clamping means for clamping the target on the table, the clamping means between the contact surfaces (A, B) between the target and the target table and the contact surfaces (A, B) A layer of stationary liquid (3) in contact, wherein the layer of stationary liquid (3) is such that the spacing between the target and the target table causes a capillary pressure drop (Pcap). (A, B) included in the capillary formed between the target table (2) The method in which a plurality of spacers (15) or projections which define the thickness of the stationary layer of liquid (3) (7) is provided.
[20] The method according to [19], wherein the lithography system is operated in a vacuum.
[21] The method of [19] or [20], wherein the target table is removed from the lithography system to replace a target on the target table.
[22] The method according to any one of [19] to [21], wherein the target tables are exchanged with each other for the purpose of exchanging a target of the lithographic apparatus.
[23] The method according to any one of [19] to [22], wherein the target table is processed outside the lithographic apparatus, and the temperature of the lithographic apparatus is adjusted in this process.

Claims (11)

A wafer table (8) for supporting said wafer (1) during processing of the wafer (1) in a lithography system,
The wafer table (8) has an upper surface (2) provided with a protrusion (7) for supporting the wafer (1),
The protrusions have a height to maintain a mutual nominal distance of 0.1 to 10 μm between the wafer (1) and the upper surface (2) of the wafer table (8);
The mutual nominal distance is a height (h) of a gap between the upper surface (2) and the wafer (1) when the wafer is supported by the protrusion (7),
The wafer table is configured to include a layer of stationary liquid (3) in the gap between the upper surface (2) of the wafer table (8) and the wafer (1),
The wafer table (8) has a peripheral gutta located at the periphery of the wafer transport portion (2) of the wafer table;
The gutta has a width that is significantly greater than the height (h) of the gap;
The outer rim of the wafer table is arranged to leave a very slight vertical spacing (9B) relative to the wafer (1) when the wafer (1) is supported by the protrusions (7). Have a ring
The wafer table, wherein the very slight vertical spacing (9B) is 1/20 to 1/10 of the height of the protrusion.   The wafer table according to claim 1, wherein the ring closes most of the peripheral gap (9B) between the wafer table (8) and the wafer (1) supported by the protrusion (7).   The wafer table according to claim 1 or 2, wherein the wafer table (8) is provided with a plurality of peripheral openings (10B).   The wafer table according to claim 3, wherein the plurality of peripheral openings (10B) are included in the gutta.   2. The wafer table according to claim 1, wherein the protrusions (7) are evenly distributed on the wafer table (8).   A lithography system comprising the wafer table of claim 1. The lithography system according to claim 6 , further comprising dispersion means for dispersing liquid on the upper surface (2) of the wafer table (8). Further comprising a wafer (1) supported by the protrusions (7) of the wafer table (8);
A layer of static liquid (3) is included between the wafer table (8) and the wafer (1), and the layer of static liquid includes both the wafer table (8) and the wafer (1). The lithographic system of claim 6 , wherein the layer of stationary liquid (3) has a thickness defined by the height of the protrusion (7). Lithographic system according to claim 6 , wherein the layer of stationary liquid (3) is a layer of water. A lithography system according to claim 6 , configured to project an image or image pattern onto the wafer (1) supported by the wafer table (8). Configured to move the wafer (1) relative to the beam source of the lithography system by a driven target table or chuck;
The wafer table (8) is formed in the lithography system with loose components, ie without connection of a plurality of conduits, in order to process the wafer (1) carried by the wafer table (8). The lithography system of claim 6 .

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