JP5600710B2 - Method for loading a substrate onto a substrate table, device manufacturing method, computer program, data carrier, and apparatus - Google Patents

Description

  The present invention relates to a method for loading a first object onto a second object in a lithography process, a device manufacturing method, a computer program and a data carrier. The method further relates to an apparatus in the lithographic apparatus constructed to hold a first object on a second object.

  A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that case, a patterning device, optionally referred to as a mask or reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (eg including part of, one, or several dies) on a substrate (eg a silicon wafer). Pattern transfer is generally by imaging onto a layer of radiation sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. In known lithographic apparatus, each target portion is irradiated by exposing the entire pattern onto the target portion in one go, a so-called stepper and a pattern via a radiation beam in a given direction (“scan” direction) While scanning the substrate synchronously or parallel to this direction, each target portion is illuminated so-called scanner. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

  When the substrate is positioned on the substrate table, thermal and mechanical stresses can be induced in the substrate, which can negatively affect high quality pattern transfer. Therefore, the purpose is to reduce stress.

According to one aspect, a method for loading a first object onto a second object in a lithography process comprising:
a) loading a first object onto a second object;
b) waiting for a certain amount of time,
c) A method is provided that includes performing a stress relaxation action to relieve stress experienced by at least one member of the group comprising the first object and the second object.

  According to one aspect of the present invention, there is provided a device manufacturing method comprising transferring a pattern from a patterning device onto a substrate and performing the method.

  According to another aspect of the invention, there is provided a computer program configured to perform the method when loaded on a computer device.

  A data carrier including the computer program is also provided.

According to another aspect, an apparatus in a lithographic apparatus constructed to hold a first object on a second object,
-A loading means for loading the first object onto the second object;
-Stress relaxation means for performing a stress relaxation action for removing stress experienced by at least one member comprising the first object and the second object;
An apparatus is provided that is configured to wait a certain amount of time between loading the first object.

  By way of example only, embodiments of the invention will now be described with reference to the accompanying schematic drawings, in which corresponding reference symbols indicate corresponding parts.

1 schematically depicts a lithographic apparatus according to one embodiment of the invention. 1 is a schematic cross-sectional view of a substrate support according to one embodiment. 2 is a schematic top view of a substrate support according to one embodiment. FIG. 1 is a schematic cross-sectional view of a substrate table according to one embodiment. 1 is a schematic cross-sectional view of a substrate table according to one embodiment. 1 is a schematic cross-sectional view of a substrate support according to one embodiment. 2 is a schematic top view of a substrate support according to one embodiment. FIG. 2 is a schematic view of a substrate support according to one embodiment. FIG. 1 is a schematic diagram of a computer according to one embodiment. FIG.

FIG. 1 schematically depicts a lithographic apparatus according to one embodiment of the invention. This device
An illumination system (illuminator) IL configured to condition a radiation beam B (eg UV radiation or EUV radiation);
A support structure (eg mask table) constructed to support the patterning device (eg mask) MA and connected to a first positioner PM configured to accurately position the patterning device according to several parameters MT,
A substrate table (eg a wafer table) constructed to hold a substrate (eg a resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate according to several parameters WT,
A projection system (eg a refractive projection lens system) configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (eg comprising one or more dies) of the substrate W ) PS.

  It will be appreciated that other lithographic apparatus can be present or envisioned that may include other elements. For example, a stepper or maskless exposure tool may not have the first positioner PM.

  The illumination system can be of various types, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, to induce, shape, or control radiation Types of optical components may be included.

  The support structure supports the patterning device, i.e. bears the weight of the patterning device. The support structure holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as for example whether or not the patterning device is held in a vacuum environment. The support structure can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device. The support structure may be a frame or table, for example, which may be fixed or movable as required. The support structure may ensure that the patterning device is at a desired position, for example with respect to the projection system. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device.”

  As used herein, the term “patterning device” refers to any device that can be used to provide a pattern in its cross-section to a radiation beam so as to produce a pattern in a target portion of a substrate. Should be interpreted broadly. It should be noted that the pattern imparted to the radiation beam may not correspond exactly to the desired pattern in the target portion of the substrate, for example if the pattern includes phase shift features, or so-called assist features. In general, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit.

  The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase shift, attenuated phase shift, and various hybrid mask types. One example of a programmable mirror array uses a matrix configuration of small mirrors, each of which can be individually tilted to reflect the incoming radiation beam in various directions. The tilting mirror provides a pattern in the radiation beam reflected by the mirror matrix.

  As used herein, the term “projection system” refers to a refractive optical system, a reflective optical system as appropriate for the exposure radiation used or for other factors such as the use of immersion liquid or the use of vacuum. Should be construed broadly to encompass any type of projection system, including catadioptric optical systems, magneto-optical systems, electromagnetic optical systems, electrostatic optical systems, or any combination thereof. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system”.

  As used herein, the apparatus is of a transmissive type (eg, using a transmissive mask). Alternatively, the apparatus can be of a reflective type (eg, using a programmable mirror array of the type referred to above or using a reflective mask).

  The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and / or two or more mask tables). In such “multi-stage” machines, additional tables can be used simultaneously, or on one or more tables while one or more other tables are used for exposure. A preparatory step can be performed.

  The lithographic apparatus can also be of a type that can cover at least a portion of the substrate with a liquid having a relatively high refractive index, such as water, so as to fill a space between the projection system and the substrate. An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are well known in the art by increasing the numerical aperture of projection systems. As used herein, the term “immersion” does not imply that a structure, such as a substrate, must be submerged in a liquid, and conversely, the liquid is exposed to the projection system and the substrate during exposure. It just means that it is in between.

  Referring to FIG. 1, the illuminator IL receives a radiation beam from a radiation source SO. The radiation source and the lithographic apparatus can be separate, for example when the radiation source is an excimer laser. In such a case, the radiation source is not considered to form part of the lithographic apparatus, and the radiation beam is emitted from the radiation source SO, for example with the aid of a beam delivery system BD equipped with suitable guiding mirrors and / or beam expanders. Passed to IL. In other cases the source may be an integral part of the lithographic apparatus, for example when the source is a mercury lamp. Radiation source SO and illuminator IL may be referred to as a radiation system, optionally with a beam delivery system BD.

  The illuminator IL may include an adjuster AD for adjusting the angular intensity distribution of the radiation beam. In general, at least the outer and / or inner radius ranges (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in the pupil plane of the illuminator can be adjusted. Furthermore, the illuminator IL may comprise various other components such as an integrator IN and a capacitor CO. An illuminator can be used to adjust the radiation beam to have the desired uniformity and intensity distribution in its cross section.

  The radiation beam B is incident on the patterning device (eg, mask MA), which is held on the support structure (eg, mask table MT), and is patterned by the patterning device. The radiation beam B traverses the mask MA and passes through the projection system PS, which focuses the beam onto the target portion C of the substrate W. The substrate table WT is adapted, for example, to position various target portions C in the path of the radiation beam B with the aid of a second positioner PW and a position sensor IF (eg interferometer device, linear encoder or capacitive sensor). Can move accurately. Similarly, using the first positioner PM and another position sensor (not explicitly shown in FIG. 1), the radiation beam is emitted after the mask MA has been mechanically removed, for example from a mask library, or during a scan. It is possible to accurately position with respect to the path B. In general, the movement of the mask table MT can be realized with the aid of a long stroke module (coarse positioning) and a short stroke module (fine movement positioning) which form part of the first positioner PM. Similarly, movement of the substrate table WT can be achieved using a long stroke module and a short stroke module that form part of the second positioner PW. In the case of a stepper (not a scanner), the mask table MT can be connected only to a short stroke actuator or can be fixed. Mask MA and substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. The substrate alignment marks in the figure occupy dedicated target portions, but may be located in the space between target portions (these are known as scribe lane alignment marks). Similarly, in situations where multiple dies are provided on the mask MA, the mask alignment marks may be located between the dies.

The depicted apparatus can be used in at least one of the following modes:
1. In step mode, the mask table MT and the substrate table WT remain essentially stationary, while the entire pattern imparted to the radiation beam is projected once onto the target portion C (ie, a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.
2. In scan mode, the mask table MT and the substrate table WT are scanned synchronously (ie, a single dynamic exposure) while the pattern imparted to the radiation beam is projected onto the target portion C. The speed and direction of the substrate table WT relative to the mask table MT may be determined by the (reduction) magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width of the target portion (in the non-scan direction) in a single dynamic exposure, while the length of the scan motion increases the height of the target portion (in the scan direction). Is determined.
3. In another mode, the mask table MT remains essentially stationary holding the programmable patterning device and the substrate table WT is projected while the pattern imparted to the radiation beam is projected onto the target portion C. Moved or scanned. In this mode, a pulsed radiation source is generally used, and the programmable patterning device is updated as needed after each movement of the substrate table WT or between successive radiation pulses during the scan. This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device, such as a programmable mirror array of a type as referred to above.

  Combinations and / or variations on the above described modes of use or entirely different modes of use may also be employed.

  2 and 3 show a side view and a top view, respectively, of a substrate support according to one embodiment. The substrate support is generally designated 1. The substrate support 1 comprises a support structure 2 (eg a mirror block, also called a chuck) on which the substrate table WT is placed (and possibly clamped).

  The upper side of the substrate support 1 includes a vacuum clamp 4 for clamping the substrate W on the substrate support 1. The substrate support 1 comprises three other retractable pins 5, often referred to as e-pins, which are extended positions where the pins 5 extend from the substrate support 1 and the pins 5 are retracted into the substrate support 1. It can move with respect to the substrate support 1 between the contracted positions.

  It will be appreciated that FIG. 2 illustrates a possible embodiment. According to other embodiments, the e-pin 5 may not be part of the substrate support 1 and may be part of a support structure and / or a structure that supports the substrate support 1. For example, the e-pin 5 can also be part of the second positioner PW described with reference to FIG. The retractable pins 5 are movable in a substantially vertical direction, i.e. in a direction substantially perpendicular to the main plane of the substrate W to be supported by the pins 5. The retractable pins 5 can be used to transfer a substrate W between the substrate support 1 and a robot or any other type of substrate handler. The retractable pins 5 are provided so that a robot can be placed under the substrate W to support the substrate W. When the robot is configured to hold the substrate W side or top, the retractable pins 5 may be omitted.

  The robot can place the substrate W on the pin 5 in the extended position. The pin 5 can then be moved to the retracted position, so that the substrate W stops on the support surface of the substrate support 1. After the substrate W supported by the substrate support 1 is exposed with the patterned radiation beam, it can be exchanged for another substrate. In order to replace the substrate W, the substrate W is lifted from the substrate table WT by retractable pins 5 which are moved from the contracted position to the extended position. When the pins 5 are in the extended position, the substrate W can be carried by a robot or any other type of substrate handler.

  The vacuum clamp 4 is formed by a recessed surface 6 surrounded by a sealing rim 7. In order to create a low pressure in the vacuum space bounded by the recessed surface 6, the sealing rim 7 and the substrate W placed or to be placed on the substrate support 1, an air suction conduit 8 is provided. Provided. The air suction conduit 8 is connected to the air suction pump PU in order to extract air from the vacuum space. This low pressure provides a vacuum force that pulls the substrate W above the support surface toward the substrate support 1.

  In the recessed surface 6 are arranged several bars 9 (projections) 9. The upper end of the burl 9 provides a support surface for the substrate W to be placed on the substrate support 1. The sealing rim 7 and the upper end of the burl 9 may be arranged in substantially the same plane so as to provide a substantially flat surface for supporting the substrate W with a relatively small contact area. is there. The sealing rim 7 acts as a seal and does not need to contact the substrate W. A very small gap may exist between the substrate W and the rim 7 to create a controlled leak.

  In one embodiment of the substrate support 1, more than one vacuum clamp can be provided as a clamping device. In practice, other types of clamping devices such as electrostatic clamps, magnetic clamps, or electromagnetic clamps can be provided to provide an attractive force applied to the substrate W.

  When the substrate W is positioned on the substrate table WT and clamped to the substrate table WT, the temperature of the substrate W and the temperature of the substrate table WT may be different both in distribution and in total. Also, the temperature difference may exist in the substrate W or in the substrate table WT. After the substrate W is positioned on the substrate table WT, these temperature differences are neutralized and temperature equilibrium is reached. As a result of these changing temperatures, the substrate W and the substrate table WT can deform and experience thermal stress. Thus, the substrate W is clamped on the substrate table WT and when its initial temperature just before loading deviates from the temperature of the substrate table WT, or when the substrate W and / or the substrate table WT has an initial temperature difference before loading , May be subject to thermal stress. Thermal stress can cause the substrate W to slide on the substrate table (on the burl 9), which leads to positioning errors.

  The stress in the substrate W may also be induced by positioning the substrate W on the substrate table WT. For example, when the substrate W is placed on the retractable pins 5 in the extended position, the substrate W may touch one pin 5 first and then the other pin 5. This can cause mechanical stress called load induced stress.

  It will be appreciated that stress may be induced when the substrate W is placed (and possibly clamped) on the substrate table WT. Substrate load induced stress and thermal stress are the incentives for large overlays.

  Since the substrate W may be clamped in another form that is not desirable, the projection overlay performance of the lithographic apparatus may be degraded, which may have a negative impact on product quality. .

  A possible way to reduce the thermal stress is to accurately control the temperature of the substrate W and match the temperature of the substrate table WT before loading the substrate W onto the substrate table WT. However, this is a time consuming method that requires the device to measure and control the temperature of the substrate W (and possibly the substrate table WT). Thus, accurately controlling the substrate temperature is relatively complex and costly, at the expense of throughput.

  Embodiments are provided to overcome thermal and load induced stresses that can occur as described above. According to the embodiment provided herein, the first object is first loaded onto the second object in the lithographic apparatus, and after a predetermined settling time interval that can balance the temperature difference, the first object A stress relaxation action is performed that allows the object and / or the second object to be stress relaxed or stress free. As described above, when the first object is loaded and clamped on the second object, it may not be able to relieve stress due to friction between the first object and the second object. Thus, the stress relaxation action includes reducing friction between the first object and the second object. The first object can be a substrate and the second object can be a substrate table WT. According to an alternative, the first object can be the substrate table WT and the second object can be the support structure 2 that supports the substrate table WT. The support structure may also be referred to as a chuck or a mirror block.

  Friction can be reduced by reducing the normal force applied by the second object that supports the first object. Several embodiments for doing this are described below.

A method of loading a first object onto a second object in a lithographic apparatus, comprising:
a) loading a first object onto a second object;
b) wait for a certain amount of waiting time,
c) A method is provided that includes performing a stress relaxation action.

Furthermore, a lithographic apparatus constructed to hold a first object on a second object,
a) load the first object onto the second object;
b) Wait for a certain amount of waiting time,
c) A lithographic apparatus configured to perform stress relaxation actions is provided.

  The first object can be a substrate W and the second object can be a substrate table WT. According to one embodiment, the first object can be a substrate table WT and the second object can be a support structure 2 for supporting the substrate table WT.

  Furthermore, a device manufacturing method is provided that includes transferring the pattern from the patterning device onto the substrate W and that includes performing one of the methods described in the embodiments.

  Examples of such stress relaxation actions are provided in the following embodiments.

  In one embodiment, the waiting time to wait between loading the first object on the second object and performing the stress relaxation action is a portion between the first object and the second object. Is selected to achieve optimal temperature equilibrium. For example, when an initial temperature difference of several Kelvin between the substrate W and the substrate table WT needs to be set to a difference of about 100 to 150 mK, a time interval of about 3 seconds is appropriate to balance the temperature difference. There is a possibility. Here, 150 mK can be considered as the maximum allowable temperature. Of course, this time interval depends on the initial temperature difference and the temperature characteristics of the material. In one embodiment, the time interval to wait is predetermined based on, for example, an expected or worst case temperature difference and a model for settling the temperature difference.

  The stress relaxation action is performed to reduce stress in the first object and the second object, including thermal stress and load induced stress.

  It will be appreciated that action b), ie waiting for a certain amount of waiting time, does not mean that no further or other actions can be performed during this action. For example, while waiting for a predetermined settling interval, a measurement position at which a substrate table WT on which a substrate W is loaded can be measured (measured in shape, orientation, position, etc.) from the load position. Or to the exposure position.

(Embodiment 1)
According to one embodiment, the stress relaxation action includes temporarily reducing the clamping force applied by the clamping device.

  As described above, when the substrate W is loaded onto the substrate table WT, a clamping device can be prepared and applied. The clamping device clamps the substrate W to the substrate table WT by providing an attractive force applied to the substrate. The clamping device can include at least one of a vacuum clamp, an electrostatic clamp, a magnetic clamp, and an electromagnetic clamp.

  According to this embodiment, the stress relaxation action includes temporarily reducing the clamping force.

  There is provided a method as described above, wherein action a) comprises clamping the substrate to the substrate table by using a clamping device and providing an attractive force applied to the substrate. The clamping device can include at least one of a vacuum clamp, an electrostatic clamp, a magnetic clamp, and an electromagnetic clamp. Action c) of the method can include temporarily reducing the clamping force.

  Furthermore, the apparatus further comprises a clamping device for clamping the substrate W to the substrate table WT by providing an attractive force applied to the substrate W, wherein the action a) uses the clamping device to attach the substrate W to the substrate table WT. There is provided a lithographic apparatus as described above, comprising clamping. The clamping device can include at least one of a vacuum clamp, an electrostatic clamp, a magnetic clamp, and an electromagnetic clamp. The action c) that can be performed by the lithographic apparatus can include temporarily reducing the clamping force.

  This embodiment is easy to implement in that it does not require additional hardware features. This embodiment uses hardware that is normally available in lithographic apparatus and is therefore easy and cost effective to implement. In some cases, simply unclamping the substrate W may not be sufficient to settle all of the stress in the substrate W. However, this embodiment provides a very easy way to at least settle some of the stresses present in the substrate W.

(Embodiment 2)
According to one embodiment, the stress relaxation action can include lifting the substrate W from the substrate table WT. This is done after temperature averaging has been performed, to provide room for stress relaxation. After stress relaxation has taken place, the substrate W is returned to the substrate table WT.

  As described above, the substrate table WT can include retractable pins 5 that can be used to perform stress relaxation actions by lifting the substrate W from the substrate table WT. FIG. 4a shows the substrate W loaded on the substrate table WT, with the pins in the retracted position. FIG. 4b shows the substrate W in the raised position. After performing the stress relaxation action, the substrate W is again placed on the substrate table WT.

  The above-described method is provided wherein the stress relaxation action can include lifting the substrate W from the substrate table WT. This can be done by moving the pins 5, which can be moved in a direction substantially perpendicular to the main surface of the substrate table, the pins 5 being retracted into the substrate support 1. From the contracted position, the pin 5 is moved to the extended position extending from the substrate support 1 so as to lift the substrate W from the substrate table WT. The main surface is the surface that contacts the substrate while clamping the substrate.

  Furthermore, a lithographic apparatus as described above is provided, comprising means for temporally lifting the substrate W from the main surface of the substrate table, wherein the relaxation action c) includes lifting the substrate W from the substrate table WT. The lithographic apparatus may comprise pins 5, which are movable in a direction substantially perpendicular to the main surface of the substrate table WT, and the stress relaxation action is such that the pins 5 are within the substrate table WT. Moving the pin 5 from the retracted position to the extended position to which the pin 5 extends from the substrate table WT to lift the substrate from the substrate table WT. After lifting the substrate W from the substrate table WT, the substrate W is repositioned on the main surface of the substrate table WT.

  It will be appreciated that this embodiment can be implemented in combination with previous embodiments, in which the stress relaxation action includes reducing the clamping force applied by the clamping device. The clamping force can be reduced before lifting the substrate W from the substrate table WT, and after the stress relaxation action, the substrate W can be positioned on the substrate table and then reapplied.

  This embodiment is easy to implement in that it does not require additional hardware features. This embodiment uses hardware that is normally available in lithographic apparatus and is therefore easy and cost effective to implement.

(Embodiment 3)
According to another embodiment, the stress relaxation action is performed by applying a positive pressure to the substrate W, thereby reducing the frictional force between the substrate W and the substrate table WT. If a clamping device is used, the clamping force can be reduced.

  The stress relaxation action can be performed by applying a tightly controlled positive pressure for a predetermined (short) period in the compartment between the substrate table WT and the substrate W. By doing this, it is possible to reduce the frictional force between the substrate W and the substrate table WT, and further to lift the substrate from the substrate table WT and thereby release the internal stress from the substrate W. is there. This process can be repeated when a single pulse is insufficient to remove all the stress. By using several relatively small pulses rather than one long pulse, substrate lift (ie, movement of...) That could potentially lose the substrate can be avoided. This air pulse can be generated by pressurizing a small container of air and then using a simple two-way valve to release air through a hole in the substrate table WT.

  5 and 6 schematically show a substrate holder 1 according to such an embodiment. As shown in FIG. 5, several nozzles 10 are provided. As shown in FIGS. 5 and 6, the nozzle 10 is provided between the bars 9. However, it will be appreciated that these nozzles may be provided in several bars 9. In the embodiment shown in FIGS. 5 and 6, the nozzles 10 are evenly distributed over the entire surface area bounded by the sealing rim 7. The nozzle 10 is connected to the gas supply unit via the gas supply conduit 11 and is substantially perpendicular to the recessed surface, ie to the main surface of the substrate W to be placed on the substrate table WT. It is configured to deliver jets or gas pulses in substantially orthogonal directions. To actually deliver the injection or gas pulse, the gas supply unit can be a pump (not shown) or another source of pressurized gas connected to the supply conduit 11. As shown in FIG. 5, a container CO containing a gas having a high pressure relative to the pressure near the substrate table WT is provided. A valve VA that can be controlled to open and close the supply conduit 11 is provided in the supply conduit 11. Note that any type of suitable gas, such as air, can be used to deliver the jet.

  The above-described method is provided wherein the stress relaxation action includes supplying a gas between the substrate W and the substrate table WT. The gas can be supplied by a series of at least one gas pulse.

  Furthermore, the substrate table WT comprises at least one nozzle 10, which is connected to or connectable to a gas supply unit and configured to supply gas between the substrate W and the substrate table WT. There is provided a lithographic apparatus as described above, wherein the stress relaxation action can comprise supplying a gas between the substrate and the substrate table. The lithographic apparatus may be configured to supply the gas in a series of at least one gas pulse.

  It will be appreciated that this embodiment can be implemented in combination with previous embodiments, in which the stress relaxation action includes reducing the clamping force applied by the clamping device. The clamping force can be reduced before supplying the gas and reapplied after the stress relaxation action.

(Embodiment 4)
According to another embodiment, the stress relaxation action includes vibrating the substrate table WT. By applying appropriate vibrations, the frictional force between the substrate W and the substrate table WT is reduced and the substrate is stress relieved. The vibration can occur at any suitable frequency and any suitable amplitude, eg, an amplitude of about 1 μm and a frequency of> 500 Hz or less.

  FIG. 7 schematically shows a substrate holder 1 comprising a substrate table WT on which a substrate W is loaded. FIG. 7 further shows a vibrating device formed by two actuators AC that can be used to activate the substrate holder 1 and thus to vibrate the substrate table WT.

  The vibrating device can be formed by the second positioner already described above with reference to FIG. However, a special dedicated actuator can also be provided for carrying out the vibration.

  The actuator may be specially prepared, but it is also possible to use an existing actuator such as a short stroke motor for driving the support structure. The actuator may be a Lorentz-type actuator with nm accuracy having a high bandwidth servo loop. These motors are used to position the support structure and the substrate W during exposure and measurement. By simply adding a ditter signal to the normal set point, the support structure can be commanded to move in the target direction and at the same time effect vibrational movement.

  The vibration is after the substrate W has been loaded onto the substrate table WT so that the substrate W and the substrate table WT can at least partially settle the temperature difference within or between each other. Only the amount of time is added. This amount of time is selected such that the difference is expected to be lower than the maximum allowable temperature difference. The possible applied clamping force can be reduced and the substrate table WT can be vibrated at a high frequency. The vibration may have a small position amplitude and a large acceleration. This mechanical “dita” motion can be used to overcome the frictional force between the substrate W and the substrate table WT. The substrate W will then release its internal stress.

  The vibration can be applied in a direction that is substantially orthogonal to the surface of the substrate table WT, ie, substantially orthogonal to the major surface of the substrate W that is to be disposed on the substrate table WT. During the downward movement, the normal force (and hence the frictional force) applied by the substrate table WT to the substrate W is temporarily reduced and the substrate W can be stress relieved.

  According to a variant, the vibration is in a direction substantially parallel to the surface of the substrate table WT, ie substantially parallel to the main surface of the substrate W to be arranged on the substrate table WT. Added in. As a result of this movement, the substrate W and the substrate table WT can move relative to each other, thereby reducing the friction force and allowing the substrate W to relieve stress (the static coefficient of friction is a dynamic friction coefficient). Note that it is higher than the coefficient). In an alternative embodiment, the vibration is applied in a direction other than the two directions described herein, eg, an oblique direction having both a component parallel to and orthogonal to a component parallel to the surface of the substrate table WT.

  In other embodiments, the vibration is applied directly to the substrate. The vibration action can be applied by using a vibration tool such as a spring or a flexible element. This vibration tool can be activated. Any suitable actuator can be used. In one embodiment, the vibration action is applied on the substrate starting within the center of the substrate. Vibrating action can be applied to the substrate / object by a central gripper. In other steps, the vibration action can be applied to a more external portion of the object. In this way, the stress in the object is preferably “moved”, preferably “released” to the outer part of the object. In one embodiment, an E pin is used as the vibration device to vibrate the object.

  The oscillating action can be a very short action, eg only one period or even a half period. The vibration action is characterized by movement relative to at least one action, preferably a balanced position. This can be an offset movement. It is believed that such an oscillating action would have a stress reducing effect within the object, since the oscillating action can cause a wave-like stress relief lobe that moves through the object material. Such wave-like motion is considered to be more effective in reducing local stresses in the object.

  In other embodiments, a striking device can be used to apply vibrations to the object. By hitting the object, a temporary disturbance, in this case excessive disturbance, is transmitted over the object, which can be used to dissipate or release other internal stresses across the object. The striking device can also initiate a wave-like movement within the object.

  In one embodiment, vibrations are applied to the substrate and substrate table, partially simultaneously or one at a time.

  A method and lithographic apparatus are provided in which a substrate table and / or substrate is vibrated at a high frequency and a small amplitude. Furthermore, a lithographic apparatus as described above is provided, wherein the substrate table comprises a vibrating device and the stress relaxation action comprises vibrating the substrate table.

  It will be appreciated that this embodiment can be implemented in combination with previous embodiments, in which the stress relaxation action includes reducing the clamping force applied by the clamping device. The clamping force can be reduced before supplying the gas and reapplied after the stress relaxation action.

(Embodiment 5)
The above embodiments describe how to load a substrate W onto the substrate table WT. However, the substrate table WT itself can be a separate part positioned on the support structure 2. The substrate table WT can be clamped to the support structure 2 using a clamping device including at least one of a vacuum clamp, an electrostatic clamp, a magnetic clamp, and an electromagnetic clamp.

  The same stress relaxation procedure described above can be applied to the substrate table when a stress eventually occurs in the substrate table that causes slippage between the substrate table WT and the support structure 2.

  Loading the substrate table WT onto the support structure 2 can involve the same problems as loading the substrate W onto the substrate table WT, ie, thermal and mechanical stresses are induced in the substrate table WT. It will be understood that

  Thus, the embodiment described above can also be used to load the substrate table WT onto the support structure 2.

Thus, a method for loading a substrate table onto a support structure, comprising:
a) loading the substrate table onto the support structure;
b) wait for a certain amount of waiting time,
c) A method is provided that includes performing a stress relaxation action.

  Action a) can include clamping the substrate table to the support structure by using a clamping device and providing an attractive force applied to the substrate table. The clamping device can include at least one of a vacuum clamp, an electrostatic clamp, a magnetic clamp, and an electromagnetic clamp.

  Action c) can include temporarily reducing the clamping force and / or can include supplying gas between the substrate table and the support structure. The gas can be supplied by a series of at least one gas pulse.

  Action c) may further comprise vibrating the support structure. The support structure can be vibrated at a high frequency and a small amplitude.

  Vibration is applied at short time intervals after the substrate table is loaded onto the support structure. In one embodiment, the clamping force is reduced. Alternatively or additionally, the support structure is vibrated at a high frequency. The vibration has a small position amplitude and a large acceleration. This mechanical “dita” motion is used to overcome the frictional force between the substrate table WT and the support structure. The substrate W will then release its internal stress.

Action c) may further comprise lifting the substrate table WT from the support structure 2, for example by moving the pins, the pins being in a direction substantially perpendicular to the main surface of the support structure. These pins are movable and are moved from a retracted position where the pins are retracted into the support structure to an extended position where the pins extend from the support structure to lift the substrate table from the major surface of the support structure.

  The amount of waiting time can be selected so that the substrate W and the substrate table WT can at least partially settle the temperature difference within or between each other.

  Action c) can be performed to reduce the stress in the substrate table WT.

Further, a lithographic apparatus comprising a support structure 2 constructed to hold a substrate table WT,
a) Load the substrate table WT onto the support structure 2,
b) Wait for a settling time interval,
c) A lithographic apparatus configured to perform stress relaxation actions may be provided.

(Computer)
All of the above embodiments can be implemented using a computer CO, for example as shown in FIG. The computer CO may comprise a processor PR configured to communicate with the input / output device I / O and the memory ME.

  The computer CO can be a personal computer, a server, or a laptop. All these devices are different types of computers. The memory ME may comprise instructions readable and executable by the processor PR in order to cause the computer CO to implement the described embodiment. The computer CO may be configured to interact with other parts of the lithographic apparatus via input / output device I / O to implement the described embodiments.

  FIG. 8 shows a schematic block diagram of an embodiment of a computer CO comprising a processor PR for performing operations. The processor PR is a memory ME that can store instructions and data, such as a tape unit, a hard disk, a read only memory (ROM), an electrically erasable programmable read only memory (EEPROM), and a random access memory (RAM). Connected to.

  The input / output device I / O is configured to communicate with other computer systems or devices included in the lithographic apparatus 1 (not shown) via a communication link.

  However, it should be understood that more and / or other memories ME and processors PR may be provided. Further, one or more of them may be physically located at a remote location. The processor PR is shown as one box, but as is known to those skilled in the art, several may be located remotely from one another, function in parallel, or controlled by one main processor Processor PR.

  Note that although all connections are shown as physical connections, one or more of these connections can be wireless. They are only intended to show that “connected” units are configured to communicate with each other in some way.

  When loaded on a computer device, a computer program configured to perform any one of the provided methods is provided. A data carrier including such a computer program is also provided. The data carrier can be any type of computer readable medium.

(Other notes)
The embodiments described above describe options for reducing the clamping force. It will be appreciated that this can be done in combination with all other embodiments. Also, reducing the clamping force includes reducing the clamping force to substantially zero, i.e., applying no clamping force at all.

  The embodiment of sending gas and the embodiment of applying vibration can be applied with a relatively small throughput loss. Also, there is no restriction on the substrate table position within the existing metrology sequence where stress relaxation actions can be performed.

  When lifting the substrate W from the substrate table WT (Embodiment 2), this may have a negative impact on pre-alignment accuracy. Furthermore, for machine / substrate safety, lifting the substrate (Embodiment 2) can only be done at a very special location of the substrate table WT, where throughput is not optimal.

  Based on the above description, it will be appreciated that the stress relaxation action is implemented to temporarily reduce the friction between the substrate W and the substrate table WT, to relieve the substrate W and relieve stress. Numerous methods are provided for performing stress relaxation actions, such as reducing the clamping force, lifting the substrate W, sending gas between the substrate W and the substrate table WT, vibrating the substrate table WT, etc. The

  It is understood that the stress relaxation action should be performed so that the substrate W is accurately positioned with respect to the substrate table WT after the stress relaxation action to allow accurate processing of the substrate W. Like. In practice, the substrate W is a sensor used to measure the position and orientation of the substrate W, such as an alignment sensor for measuring the horizontal orientation of the substrate and a level sensor for measuring the surface profile of the substrate. Should be within the capture range. The capture range is about several tens of microns.

  After the stress relaxation action, other measurement actions can be performed to measure the position and orientation of the substrate W.

  It will also be appreciated that all of the embodiments may be used in combination with one or more other embodiments. For example, the vibration can be performed in combination with reducing the supply gas and / or the clamping force.

  These embodiments can be implemented to temporarily overcome the frictional force between the first object and the second object so that the first object can settle.

  Although specific references may be made throughout the text to the use of a lithographic apparatus in the manufacture of ICs, the lithographic apparatus described herein includes integrated optical systems, guides and detection patterns for magnetic domain memories. It should be understood that there may be other applications such as the manufacture of flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like. In the context of such alternative fields of application, any use of the terms “wafer” or “die” herein may refer to the more general terms “substrate” or “target portion”, respectively. Those skilled in the art will understand that they can be considered synonymous. The substrate referred to herein may be used before and after exposure, for example, in a track (typically a tool that applies a layer of resist to the substrate and develops the exposed resist), metrology tool, and / or inspection tool. Can be processed. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. In addition, the substrate can be processed multiple times, for example to create a multi-layer IC, so that the term substrate used herein can also refer to a substrate that already contains multiple processed layers. is there.

  In the above, the use of embodiments of the present invention may be specifically referred to in the context of optical lithography, but the present invention can be used in other applications, such as imprint lithography, It will be understood that the invention is not limited to optical lithography where possible. In imprint lithography, the topography within the patterning device defines the pattern that is produced on the substrate. The topography of the patterning device can be pushed into a layer of resist supplied to the substrate, at which time the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. The patterning device is moved out of the resist after the resist is cured, leaving a pattern in the resist.

  The terms “radiation” and “beam” as used herein refer to ultraviolet (UV) radiation (eg, having a wavelength of about 365, 355, 248, 193, 157, or 126 nm), and (eg, 5 Includes all types of electromagnetic radiation, including extreme ultraviolet (EUV) radiation (with wavelengths in the range of ˜20 nm), as well as particle beams such as ion beams or electron beams.

  The term “lens” refers to any one of various types of optical components, including refractive optical components, reflective optical components, magneto-optical components, electromagnetic optical components, and electrostatic optical components, where possible in the context. Or it may refer to a combination.

  While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the invention may be a computer program that includes one or more sequences of machine-readable instructions that describe the methods disclosed above, or a data storage medium (eg, a semiconductor memory) on which such a computer program is stored. , Magnetic disk, or optical disk).

  The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims (14)

A method of loading a first object onto a second object in a lithographic apparatus, comprising:
Loading the first object onto the second object;
Waiting until temperature equilibrium is achieved between the first object and the second object;
Friction between the first object and the second object by performing a relaxation action after waiting for temperature equilibrium to be achieved between the first object and the second object With reducing power,
The mitigation action includes vibrating the second object by striking the second object.   The method of claim 1, wherein the first object is a substrate and the second object is a substrate table.   The method of claim 1, wherein the first object is a substrate table and the second object is a support structure that supports the substrate table.   The loading includes clamping the first object to the second object by using a clamping device and providing an attractive force applied to the first object. The method according to claim 3.   The method of claim 4, wherein the clamping device comprises at least one of a vacuum clamp, an electrostatic clamp, a magnetic clamp, and an electromagnetic clamp.   6. A method according to claim 4 or claim 5, wherein the relaxation action comprises temporarily reducing the clamping force.   The method of claim 1, wherein the second object is vibrated at a high frequency and a small amplitude.   The relaxation action includes moving a pin, the pin is movable in a direction substantially perpendicular to a major surface of the second object, the pin being the second pin. The method of claim 1, wherein the pin is moved from a retracted position retracted into a second object to an extended position extending from the second object to lift the first object from the second object. .   9. A method according to any one of the preceding claims, wherein the relaxation action is performed to reduce stress in the first object.   The method according to claim 1, wherein the relaxation action includes temporarily lifting the first object from the second object.   The method according to claim 1, wherein the relaxation action includes oscillating the second object so that the second object moves. A system comprising a lithographic apparatus constructed to hold a first object on a second object,
The lithographic apparatus comprises:
Loading the first object onto the second object;
Wait until temperature equilibrium is achieved between the first object and the second object;
Friction between the first object and the second object by performing a relaxation action after waiting for temperature equilibrium to be achieved between the first object and the second object Configured to reduce power,
The mitigation action includes vibrating the second object by striking the second object. The lithographic apparatus comprises a lifting device for lifting the first object from the second object;
The system of claim 12 , wherein the mitigating action includes temporarily lifting the second object from the first object. A method of loading a first object onto a second object in a lithography process, comprising:
a) loading the first object onto the second object;
b) waiting until temperature equilibrium is achieved between the first object and the second object;
c) Stress experienced by at least one member of the group including the first object and the second object after waiting for temperature equilibrium to be achieved between the first object and the second object Performing stress relaxation actions to remove
The method wherein the action c) comprises vibrating the second object by hitting the second object.

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