Source: https://patents.google.com/patent/EP1582929B1/en
Timestamp: 2019-07-17 01:17:33
Document Index: 45690062

Matched Legal Cases: ['Application No. 03252955', 'Application No. 03257072', 'application No. 03257070', 'application No. 03254078', 'arts 40', 'art 40', 'art 40', 'art 60', 'art 40', 'arts 40', 'in fine', 'art 60', 'art 40', 'art 40', 'art 40']

EP1582929B1 - Lithographic apparatus and device manufacturing method - Google Patents
EP1582929B1
EP1582929B1 EP20050251708 EP05251708A EP1582929B1 EP 1582929 B1 EP1582929 B1 EP 1582929B1 EP 20050251708 EP20050251708 EP 20050251708 EP 05251708 A EP05251708 A EP 05251708A EP 1582929 B1 EP1582929 B1 EP 1582929B1
EP20050251708
EP1582929A1 (en
Franciscus Andreas C. J. Spanjers
Petrus Marinus Ch. M. Van De Biggelaar
Jan-Gerard Cornelis Van Der Toor
2004-04-02 Priority to US816189 priority
2005-03-21 Application filed by ASML Netherlands BV filed Critical ASML Netherlands BV
2005-10-05 Publication of EP1582929A1 publication Critical patent/EP1582929A1/en
2010-05-12 Publication of EP1582929B1 publication Critical patent/EP1582929B1/en
2018-09-12 First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=34887757&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP1582929(B1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Another solution which has been proposed is to provide the liquid supply system with a seal member which extends along at least a part of a boundary of the space between the final element of the projection system and the substrate table. An example is illustrated in Figure 4. The seal member is substantially stationary relative to the projection system in the XY plane though there may be some relative movement in the Z direction (in the direction of the optical axis). A seal is formed between the seal member and the surface of the substrate. Preferably the seal is a contactless seal such as a gas seal. Such as system is disclosed in European Patent Application No. 03252955.4 .
In European Patent Application No. 03257072.3 , corresponding to the published European Patent Application EP 1 420 300 A , the idea of a twin or dual stage immersion lithography apparatus is disclosed. Such an apparatus is provided with two stages for supporting the substrate. Leveling measurements are carried out with a stage at a first position, without immersion liquid, and exposure is carried out with a stage at a second position, where immersion liquid is present.
Alternatively, the apparatus has only one stage.
It is an object of the present invention to improve immersion lithography performance. It is a further object of the present invention to improve through-put, overlay and critical dimension performance of an immersion lithography apparatus.
a liquid supply system for providing an immersion liquid between a final element of said projection system and said substrate;and
at least one actuator for applying a force on said substrate; characterised by further comprising:
a compensation controller arrranged to calculate a compensating force to be applied by said at least one actuator on said substrate wherein said compensating force is substantially equal in magnitude and opposite in direction to force applied to said substrate by said liquid supply system.
In this way any disturbance forces transmitted by the liquid supply system to the substrate do not affect the position of the substrate. Any source of force from the liquid supply system can be compensated in this way. Examples include force applied to the substrate by the liquid supply system due to gravity, due to variations in pressure in the immersion liquid and variations in pressure of liquid and/or gas being removed at a gas seal around the perimeter of a barrier member which gas seal seals between the barrier member and the substrate. If the liquid supply system comprises a barrier member which is positioned in a direction parallel to the optical axis of the projection system using a barrier actuator, the compensation controller can calculate the required compensation force based on the force needed by the barrier actuator to keep the barrier member steady or by the signals given off by a force sensor attached between the barrier member and the projection system. These are the many sources of disturbance forces transmitted to the substrate by the liquid supply system, all of which can be compensated for by the compensation controller for controlling the actuator.
Preferably the compensation controller calculates the compensation force in a feed-forward manner. For example, the compensation controller can calculate the compensation force based on a desired position of the substrate. This can be done from a calculation of the force of gravity on the liquid supply system, especially in the case of the presence of a barrier member. This is done particularly in the case of a localized area liquid supply system, where the components of the liquid supply system remain stationary in the plane orthogonal to the optical axis of the projection system. This is because the position, relative to the center of gravity of the substrate table, at which force from the liquid supply system is transmitted to the substrate, varies with the position of the substrate table. This can lead to rotational torques in the plane orthogonal to the optical axis which, if not, compensated for by the compensation controller, would lead to a reduction in imaging performance of the apparatus, particularly imaging and overlay.
There may be other occasions when the liquid supply system exerts a force on the substrate table directly without exerting the same force on the substrate. In such circumstances the compensation controller may control the at least one actuator to apply compensating force on the substrate table substantially equal in magnitude and opposite in direction to the force applied to the substrate table by the immersion liquid supply system.
The apparatus may further comprise a pressure sensor for measuring the pressure in the immersion liquid and/or gas and/or liquid pressure in the gas seal. This is particularly useful if the compensation controller calculates the compensating force based on variations in pressure in the immersion liquid either in the space or in the gas seal.
providing an immersion liquid between a final element of said projection system and said substrate; and
calculating and applying a compensating force on said substrate substantially equal in magnitude and opposite in direction to force applied to said substrate by said liquid supply system.
Figure 2 illustrates, in cross-section, a liquid supply system which may be used with the present invention;
Figure 3 illustrates the liquid supply system of Figure 2 in plan;
Figure 4 illustrates, in plan and in cross-section, another liquid supply system which may be used in the present invention;
Figure 5 illustrates, in cross-section, a substrate table and liquid supply system according to the present invention;
Figure 6 illustrates the positional dependence of the substrate table on the compensation force required; and
Figure 7 illustrates two possible ways of establishing the compensation force required.
The present invention concerns measures which can be taken to reduce the disturbance forces introduced by the supply of liquid between the final element of the projection system and the substrate in immersion lithography. The present invention is applicable to any type of liquid supply system, in particular localized area liquid supply systems which supply liquid to only a localized area of the substrate (c.f. a bath in which the substrate and perhaps substrate table are immersed).
Figures 2 and 3 illustrate a first type of liquid supply system in which the liquid supply system is supported in the Z direction by a base frame BF or a metrology reference frame RF (which is supported by but isolated from the base frame). On the other hand, Figure 4 illustrates a liquid supply system using a barrier member which has an orifice in which the final element of the projection system PL is situated. Thus, the barrier member at least partly surrounds the final element of the projection system PL and forms a space for immersion liquid between the final element of the projection system and the substrate W. This type of liquid confinement system can either have its weight supported by the projection lens PL, by the base frame BF or any other frame or may support its weight through a hydro-static, hydro-dynamic or air bearing on the substrate W.
A further generic type of liquid confinement system comprises a barrier member which at least partly surrounds the bottom of the projection lens and forms a space, defined by the substrate, the barrier member and the final element of the projection system PL, to which liquid is supplied. Such a liquid supply system is disclosed in, for example, European Patent application No. 03257070.7 , corresponding to published European Patent Application EP 1 420 298 A , and 03256643.2 In that document, the barrier member has a gas bearing on its under side which is used to support the weight of the barrier member on the substrate W. The barrier member is connected to the base frame BF but only substantially to prevent movement in the XY plane. Alternatively, a similar barrier member may be used in which hydrostatic pressure is used to support the barrier member on the substrate W. Such a system is disclosed in European Patent application No. 03254078.3 , corresponding to published European Patent Application EP 1 498 778 A . A further variation of the barrier member is disclosed in USSN 10/743,271 filed 23 December 2003 , corresponding to United States Patent Application Publication US 2005/134815 A ..
The materials of which the above mentioned liquid supply systems are constructed, and in particular the barrier members, are chosen so that they have no adverse effects on contact with the immersion liquid (e.g. corrosion), they do not deteriorate the quality of the immersion liquid e.g. by dissolving in the immersion liquid, and they are compatible with all other requirements related to lithography that are not specific to immersion. Typical examples include austenitic stainless steels (e.g. the AISI 300 series and equivalents), nickel and nickel-based alloys, cobalt and cobalt-based alloys, chromium and chromium-based alloys, titanium and titanium-based alloys. However, in order to prevent galvanic corrosion, it is best to avoid combinations of several different metals in the design. Polymers may also be used and suitable polymers include many fluorine-based polymers (e.g. PTFE (Teflon (RTM)), PFA and PVDF) also, uncolored PE and PP could be used as well as all ceramic materials, with the exception of aluminum nitride. Ceramic-based composite materials may also be suitable as may be glasses (e.g. fused silica or quartz glass) and low thermal expansion glasses or glass ceramics (e.g. ULE (TM) from Coming or Zerodur (TM) from Schott).
The present invention relates to all of the above mentioned liquid supply systems and reduces the disturbance forces which are transmitted to the substrate by the liquid supply system.
Disturbance forces which might be transmitted to the substrate include forces due to gravity (for those liquid supply systems which are at least in part supported by the substrate) and the effect of immersion liquid pressure on the substrate W (for all types of liquid supply system). Other disturbance forces are, for example, from gas bearings or gas seals on the underside of a barrier member or due to activated movements in the z, Rz, Rx and Ry directions of the liquid supply system. The gas bearing or seal removes liquid and gas from the liquid supply system. The pressure of the liquid and/or gas can vary and cause disturbance forces to be transmitted to the substrate table.
The substrate table WT assembly is illustrated in Figure 5. What is illustrated in Figure 5 is an example only and the substrate table WT may have a different construction. The principals explained in relation to Figure 5 (and Figures 6 and 7) are equally applicable to other types of substrate table WT as well as, of course, other types of liquid supply system.
In Figure 5, a liquid supply system with a barrier member 10 is illustrated. A gas seal 15 seals between the bottom of the barrier member 10 and the substrate W. The barrier member 10 provides a space 5 which can be filled with immersion liquid so that the space between the final element of the projection system PL, the substrate W and bounded by the barrier member 10 is filled with immersion liquid. The apparatus includes a compensation controller for controlling at least one actuator 45 to apply a compensating force on the substrate W substantially equal in magnitude and opposite in direction to force applied to the substrate by the liquid supply system.
The substrate table WT is comprised of two main parts 40, 60. The upper main part 40 is designed for accurate fine positioning of the substrate W, which is carried by the upper main part 40. The lower main part 60 is moved by positioning means 65 on a course scale, final accurate positioning being achieved by movement of the upper main part 40 by actuators 45 which act between the upper and lower main parts 40, 60. The present invention is described below by referring to actuators 45 between the main upper and lower parts of the substrate table 40, 60 but of course is equally applicable to other substrate tables for example those types that only have one part or indeed those types that have more than two parts. The invention is described in relation to actuators 45 being the main fine three dimensional positioning actuators though the invention may be performed with separate actuators specifically for applying the compensating forces required. These compensating forces may even be applied directly to the substrate W or could indeed be applied by the actuator means 65 for the main lower part of the substrate table WT.
Both sets of actuators 45, 65 are capable of moving their respective parts of the substrate table 40, 60 in the XY plane and, to a more limited extent, in the Z direction relative to the lower main part 60 and to the base frame BF respectively.
Figure 6 illustrates how the present invention uses the compensation controller 30 for calculating the necessary compensation force and for controlling the actuator 45 to compensate for the effect of gravity of the barrier member 10 on the substrate W in the case where the barrier member 10 is supported by the substrate W (for example through a hydrostatic, hydrodynamic or air bearing). The calculations preferably account for Rx, Ry and Rz rotational movements as well as z movements. The same principals can be applied to other types of liquid supply system when considering the effects of disturbance forces transmitted through the immersion liquid and which will be described in more detail in relation to Figure 7. However, the same principals apply for the compensation of gravity forces, because in both cases the force applied to the substrate table W can be estimated as being through the center of gravity of the barrier member 10 or the center of the area of substrate covered by immersion liquid from the liquid supply system in the case of compensating for disturbances transmitted through the immersion liquid.
Figure 6 illustrates the real life 3-dimensional problem in two dimensions. Although the weight of the barrier member 10 is constant, as can be seen from Figure 6, when the center of the substrate W moves away from directly underneath the optical axis of the projection system (indicated as dotted line 1) a moment 100 around the center of gravity of the upper part of the substrate table 40 is generated. In the case illustrated in Figure 6 this requires a larger compensating force F1 to be applied on the left hand actuator 45 than the compensating force F2 applied to the right hand actuator 45. The actuators 45 must apply a force to support both the upper part 40 of the substrate table and the barrier member. If the substrate table WT were moved to the right, the force on the left hand actuator F1 would increase and the force on the right hand actuator F2 would need to reduce. Thus, it can be seen that the compensation controller can calculate the compensating force based on a desired position of the substrate W and control the actuator 45 accordingly. The calculation can also be carried out using the actual x, y position as this is usually only a few nm different to the desired position.
The actuators are controlled to apply compensating force on the substrate table substantially equal in magnitude and opposite in direction to the force applied to the substrate by the liquid supply system.
It is also possible that the liquid supply system applies forces to the substrate table WT directly and not through the substrate. In this case the same principals apply and the compensation controller can compensate for any disturbances caused in this way.
The compensation controller 30 can calculate the compensation force in a feed-forward manner by being fed the desired (or actual) co-ordinates of the substrate W. From this information the combined center of gravity of the upper part of the substrate table 40 and of the barrier member 10 can be calculated from a knowledge of their positions and masses and the force applied to actuator 45 as appropriate. Clearly the calculations can be based on any point in space. The calculations can be carried out from a knowledge of the mass of the barrier member 10 and its position as well as the mass of the upper part 40 of the substrate table, including the substrate W.
The compensation controller 30 can additionally or alternatively calculate the compensation force required due to pressure of the liquid and/or gas in the gas seal or pressure of liquid in the space. The pressures can be measured and the calculation performed in a feed forward or feed back manner. For this purpose a pressure sensor 80 is provided or the data from the force sensor 70 can be used. Alternatively, the pressure can be calculated from, for example, a knowledge of the flow rate of liquid into and/or out of the space 5. In this way the inherent variations in pressure of the immersion liquid in the space 5 due to extraction of air/water mixture can be compensated.
As can be seen, a compensation force component is added to the overall force signal generated for each of the actuators 45. The other components include that for positioning of the substrate W as well as that for compensating the force of gravity on the upper part 40.
Alternatively, if the barrier member 10 is partly supported by another part of the apparatus other than the substrate or substrate table, and is actuated in the Z direction by an actuator 70, it is possible to measure the force on the substrate W from a knowledge of the force applied by the actuator 70. The actuator 70 may be a electromagnetic motor, a piezoelectric motor, an air bearing between the barrier member 10 and the substrate W or a hydrostatic or hydrodynamic bearing or any other sort of actuator. Information about the forces applied by the actuators can be used to calculate the force on the substrate W and used (in a feed-forward manner) to calculate the compensation force required. Alternatively or additionally the element 70 may be a force sensor 70 which outputs a signal representing the force between the barrier member and the projection lens which can be used by the compensation controller to calculate the required compensation force.
The compensation force may be filtered (and thereby corrected) for certain dynamic properties of the barrier member 10 (such as bending for example) and possible bearing characteristics (such as elasticity).
The compensation controller may also calculate the compensation force in a feedback manner based on any variable other than the position of the table. For example the feedback calculation may be on the basis of the force sensor 70 output or the actuator force or the pressure of the liquid in the space and/or at the seal and/or the gas pressure at the seal.
As stated above, the pressure of liquid in space 5 and the gas seal can apply a force (pressure times area) to the substrate W or substrate table WT. The moment applied to the upper part of the substrate table 40 by the immersion liquid is also positionally dependent and the force can be calculated from a knowledge of the pressure of immersion liquid in the space 5 and the surface area over which that pressure is applied.
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 description is not intended to limit the invention. The invention is defined by the following claims.
- an illumination system (IL) for providing a projection beam (PB) of radiation;
- a support structure (MT) for supporting patterning means (MA), the patterning means serving to impart the projection beam with a pattern in its cross-section;
- a substrate table (WT) for holding a substrate (W);
- a liquid supply system for providing an immersion liquid between a final element of said projection system and said substrate; and
- at least one actuator (45;65) for applying a force on said substrate; characterised by further comprising:
- a compensation controller (30) arranged to calculate a compensating force to be applied by said at least one actuator on said substrate wherein said compensating force is substantially equal in magnitude and opposite in direction to force applied to said substrate by said liquid supply system.
An apparatus according to claim 1, wherein said compensation controller calculates said compensation force in a feed-forward manner.
An apparatus according to claim 1, wherein said compensation controller calculates said compensation force in a feedback manner.
An apparatus according to claim 1, wherein said compensation controller calculates a compensation force that is filtered and corrected for dynamic properties of the liquid supply system.
An apparatus according to claim 1, wherein said compensation controller calculates said compensation force based on an actual or a desired position of said substrate.
An apparatus according to claim 1, wherein said compensation controller controls said at least one actuator to apply a compensating force on said substrate table substantially equal in magnitude and opposite in direction to force applied to said substrate table by said liquid supply system.
An apparatus according to claim 1, wherein said compensation controller calculates said compensation force based on force applied to said substrate by said liquid supply system due to gravity.
An apparatus according to claim 1, wherein said liquid supply system comprises a barrier member (10) at least partly surrounding said final element of said projection system thereby to define a space (5) between said final element of said projection system and said substrate for being at least partially filled with immersion liquid.
An apparatus according to claim 8, wherein said barrier member is at least partly supported by said substrate and/or substrate table.
An apparatus according to claim 8, wherein said barrier member is positioned in a direction parallel to the optical axis of the projection system using a barrier actuator (70).
An apparatus according to claim 10, wherein said barrier actuator is an air bearing, a hydrodynamic or hydrostatic bearing.
An apparatus according to claim 10, wherein said compensation controller calculates said compensating force based on the force needed by said barrier actuator to keep said barrier member steady.
An apparatus according to claim 1, wherein said compensation controller calculates said compensating force based on variations in pressure in said immersion liquid or variations in pressure of liquid and/or gas in a gas bearing of said liquid supply system.
An apparatus according to claim 13, further comprising a pressure sensor (80) for measuring said pressure in said immersion liquid and/or a force sensor for measuring a force between said liquid supply system and said projection system.
An apparatus according to claim 1, wherein said actuator is for applying force to at least part of said substrate table which supports said substrate.
An apparatus according to claim 15, wherein said compensation controller calculates said compensating force based on the desired or actual position of the center of gravity of said part of said substrate table supporting said substrate relative to said projection system.
An apparatus according to claim 1, wherein said compensation controller is for applying a compensating force on said substrate in the direction of the optical axis of the projection system, and rotationally about axes orthogonal to said optical axis of the projection system.
- providing a substrate (W);
- providing a projection beam (PB) of radiation using an illumination system (IL);
- using patterning means (MA) to impart the projection beam with a pattern in its cross-section;
- projecting the patterned beam of radiation onto a target portion of the substrate using a projection system (PL);
- providing an immersion liquid between a final element of said projection system and said substrate; and
- calculating and applying a compensating force on said substrate substantially equal in magnitude and opposite in direction to force applied to said substrate by said liquid supply system.
A method according to claim 18, wherein said compensation force is calculated in a feed-forward manner.
A method according to claim 18, wherein said compensation force is calculated in a feedback manner.
A method according to claim 18, wherein said compensation force is calculated based on the actual or a desired position of said substrate.
A method according to claim 18, wherein said compensation force is calculated based on force applied to said substrate by said liquid supply system due to gravity.
A method according to claim 18, wherein said compensating force is calculated based on variations in pressure in said immersion liquid.
EP20050251708 2004-04-02 2005-03-21 Lithographic apparatus and device manufacturing method Active EP1582929B1 (en)
US816189 2004-04-02
EP1582929A1 EP1582929A1 (en) 2005-10-05
EP1582929B1 true EP1582929B1 (en) 2010-05-12
EP20050251708 Active EP1582929B1 (en) 2004-04-02 2005-03-21 Lithographic apparatus and device manufacturing method
US20050219481A1 (en) 2005-10-06
EP1503244A1 (en) 2005-02-02 Lithographic projection apparatus and device manufacturing method
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