Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
  • G03F7/70908—Hygiene, e.g. preventing apparatus pollution, mitigating effect of pollution or removing pollutants from apparatus
  • G03F7/70916—Pollution mitigation, i.e. mitigating effect of contamination or debris, e.g. foil traps
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
  • G03F7/70808—Construction details, e.g. housing, load-lock, seals or windows for passing light in or out of apparatus
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
  • G03F7/70858—Environment aspects, e.g. pressure of beam-path gas, temperature
  • G03F7/70883—Environment aspects, e.g. pressure of beam-path gas, temperature of optical system

Definitions

• the present invention relates to a lithographic apparatus comprising a closing device and to a device manufacturing method of using the same.
• the closing device is configured to close one or more vacuum chambers for optical elements of the lithographic apparatus.
• 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).
• a patterning device which is alternatively referred to as a mask or a 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 (e.g. comprising part of, one, or several dies) on a substrate (e.g. a Silicon wafer or a Gallium Arsenide wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate.
• resist radiation-sensitive material
• a single substrate will contain a network of adjacent target portions that are successively patterned.
• lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the "scanning"-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
• the size of features that can be imaged onto the substrate may be limited by the wavelength of the projection radiation.
• UV light generated by mercury lamps or excimer lasers it has been proposed to use shorter wavelength radiation, e.g. of around 13nm.
• Such radiation is termed extreme ultraviolet (EUV) or soft x-ray, and possible sources include, for example, laser-produced plasma sources, discharge plasma sources, or synchrotron radiation from electron storage rings.
• an optics chamber of an advanced lithographic apparatus employing the EUV radiation as a source is separated from a chamber for the substrate by sharing a limited opening between the chambers.
• the opening may be part of an optical path for projecting an image on a patterning device onto a substrate, because EUV radiation is normally not transmissive to most of materials.
• both chambers are under high vacuum level during operation, the chamber for optics is normally maintained with higher pressure than the chamber for substrate, because the optics should be kept as clean as possible while the chamber for substrate is normally a source of unwanted molecules contaminations (e.g. out-gassing from resist, and particles generated due to movable parts like wafer stages).
• the pressure difference between the chambers generates a gas-flow directed from the chamber of the optics towards the chamber of the substrate to make it difficult for the contaminations to come into the chamber for the optics during the operation of the apparatus.
• a lithographic apparatus comprising a projection system in a first chamber, which projection system is configured to project an image onto a substrate, a substrate table in a second chamber, which substrate table is configured to support the substrate, wherein the first and second chambers are coupled to each other through an opening between the first and second chambers, which opening is configured to enable a gas flow between the first and second chambers, a closing device configured to substantially close the opening wherein the gas flow between the first and second chambers is still enabled when the closing device has substantially closed the opening.
• a lithographic apparatus includes a first chamber that includes a projection system. The projection system is configured to project an image onto a substrate.
• the lithographic apparatus also includes a second chamber that includes a substrate table.
• the substrate table is configured to support the substrate.
• the apparatus further includes a opening between the first chamber and the second chamber. The opening is configured to enable a gas flow between the first chamber and the second chamber.
• the apparatus also includes a closing device configured to substantially close the opening without completely sealing the opening so that the gas flow between the first chamber and the second chamber is still enabled when the closing device has substantially closed the opening.
• a device manufacturing method using a lithographic apparatus includes projecting a patterned beam of radiation onto a substrate using a projection system in a first chamber, and supporting the substrate using a substrate table in a second chamber.
• the first chamber and the second chamber are coupled to each other through an opening configured to enable a gas flow between the first and second chambers.
• the method also includes substantially closing the opening with a closing device after the projecting so that the gas flow between the first and second chambers is still enabled when the closing device has substantially closed the opening.
• Figure 1 depicts a lithographic apparatus according to an embodiment of the invention
• Figure 2 depicts a schematic view of a first chamber containing a projection system and a second chamber containing a substrate table of the lithographic apparatus of Figure 1, with an opening therebetween;
• Figure 3a depicts a schematic view of the opening of Figure 2 with the substrate table in a first position relative to the opening;
• Figure 3b depicts a schematic view of the opening of Figure 2 with the substrate table in second position relative to the opening;
• Figure 3 c depicts a schematic views of a closing device being moved into position to substantially close the opening;
• Figure 4 schematically depicts an embodiment of the closing device of Figure 3c;
• Figure 5 schematically depicts an embodiment of the closing device of Figure 3c.
• FIG. 1 schematically depicts a lithographic apparatus according to one embodiment of the invention.
• the apparatus comprises: an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV radiation, DUV radiation or EUV radiation); a support structure (e.g. a mask table) MT constructed to support a patterning device (e.g. a mask) MA and connected to a first positioner PM configured to accurately position the patterning device in accordance with certain parameters; a substrate table (e.g. a wafer table) WT constructed to hold a substrate (e.g. a resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate in accordance with certain parameters; and a projection system (e.g. a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g. comprising one or more dies) of the substrate W.
• a radiation beam B e.
• the illumination system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping, or controlling radiation.
• the support structure supports, i.e. bears the weight of, the patterning device. It 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 a 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.”
• patterning device used herein should be broadly interpreted as referring to any device that can be used to impart a radiation beam with a pattern in its cross-section such as to create a pattern in a target portion of the substrate. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so called assist features. Generally, 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, and attenuated phase-shift, as well as various hybrid mask types.
• An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in a radiation beam which is reflected by the mirror matrix.
• projection system used herein should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system”.
• the apparatus is of a reflective type (e.g. employing a reflective mask).
• the apparatus may be of a transmissive type (e.g. employing a transmissive 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 "multiple stage" machines the additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposure.
• the lithographic apparatus may also be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g. 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 for increasing the numerical aperture of projection systems.
• the illuminator IL receives a radiation beam from a radiation source SO.
• the source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In such cases, the source is not considered to form part of the lithographic apparatus and the radiation beam is passed from the source SO to the illuminator IL with the aid of a beam delivery system comprising, for example, suitable directing mirrors and/or a beam expander. In other cases the source may be an integral part of the lithographic apparatus, for example when the source is a mercury lamp.
• the source SO and the illuminator IL, together with the beam delivery system if used, may be referred to as a radiation system.
• the illuminator IL may comprise an adjuster for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer and/or inner radial extent (commonly referred to as ⁇ -outer and ⁇ -inner, respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted.
• the illuminator IL may comprise various other components, such as an integrator and a condenser. The illuminator may be used to condition the radiation beam, to have a desired uniformity and intensity distribution in its cross-section.
• the radiation beam B is incident on the patterning device (e.g., mask MA), which is held on the support structure (e.g., mask table MT), and is patterned by the patterning device. Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W.
• the substrate table WT can be moved accurately, e.g. so as to position different target portions C in the path of the radiation beam B.
• the first positioner PM and another position sensor IFl can be used to accurately position the mask MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library, or during a scan.
• movement of the mask table MT may be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM.
• movement of the substrate table WT may be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW.
• the mask table MT may be connected to a short-stroke actuator only, or may be fixed.
• Mask MA and substrate W may be aligned using mask alignment marks Ml, M2 and substrate alignment marks Pl, P2. Although the substrate alignment marks as illustrated occupy dedicated target portions, they may be located in spaces between target portions (these are known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the mask MA, the mask alignment marks may be located between the dies. [0030]
• the depicted apparatus could be used in at least one of the following modes: [0031] 1. In step mode, the mask table MT and the substrate table WT are kept essentially stationary, while an entire pattern imparted to the radiation beam is projected onto a target portion C at one time (i.e. a single static exposure). The substrate table WT is then shifted in the
• the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.
• the velocity and direction of the substrate table WT relative to the mask table MT may be determined by the (de-)magnification and image reversal characteristics of the projection system PS.
• the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, whereas the length of the scanning motion determines the height (in the scanning direction) of the target portion.
• the mask table MT is kept essentially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam is projected onto a target portion C.
• a pulsed radiation source is employed and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a 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.
• Exposure mode which can be defined as a period when a substrate (with coated resist on) is exposed by the radiation.
• Stepping mode which can be defined as a period between a completion of an exposure of a targeted portion and the beginning of the next exposure of the following target portion to be exposed.
• the substrate table WT or substrate support is moving from one target to the other.
• the stepping mode is a sub-mode of a "non-exposure period”.
• Substrate exchanging mode which can be defined as a period when one substrate is removed (unloaded) from the substrate table or substrate support and the other substrate is transferred (loaded) onto the substrate table or substrate support.
• the substrate exchanging mode is a sub-mode of the "non-exposure period".
• Swapping mode may exists only for the lithographic apparatus type having two (dual stage) or more substrate tables or substrate supports (and/or two or more mask tables or mask supports).
• the swapping mode can be defined as a period when one substrate table or substrate support and the other substrate table or substrate support are swapping its positions.
• the swapping mode is a sub-mode of the "non-exposure period”.
• FIG. 2 schematically depicts a lithographic apparatus according to a non-limiting embodiment of the invention.
• a chamber 10 e.g. vacuum chamber
• optics e.g. the projection system PS
• a chamber 20 e.g. vacuum chamber
• the opening 30 maybe a so-called dynamic gas lock (DGL), where gas flows are maintained to prevent contamination from traveling through the opening 30.
• DGL dynamic gas lock
• the gas employed in the DGL should be a substance that does not substantially absorb the radiation in the projection beam (e.g. EUV), while having a substantially low diffusion coefficient for contaminants.
• gases that have been used in dynamic gas locks are H, Ar and Kr.
• a DGL that uses gases such as Ar is described in United States Patent No. 6,198,792 Bl, which describes a hole in a membrane that separates the projection system area from the substrate area. The hole in the membrane allows for the projected radiation to impinge on the substrate. The inert gas flows across the transmission direction of the radiation beam.
• a DGL which describes a flow going in the same direction as the projected radiation, which further has a membrane or window through which the projected radiation is transmitted is described in United States Patent Nos. 6,683,936 B2 and 6,642,996 B2, and European Patent Application Publication No. 0 532 968 Al.
• the hollow tube of these latter documents that directs the inert gas may be cone-shaped and is covered at its top end by a membrane through which the radiation travels before impinging on the substrate. The membrane prevents the inert gas from flowing upwards towards the projection system.
• the first chamber 10 for optics contains the projection system PS
• the second chamber 20 for substrate table contains the substrate table WT.
• the first and the second chambers 10, 20 are coupled to each other via the shared opening 30 (DGL).
• the projection system PS may consist of reflective optics (e.g. mirrors) in which surface flatness is controlled with the atomic level. Such optics can easily be damaged if small particles come into the first chamber 10 and become attached on the surface of the optics.
• both chambers 10, 20 are under high vacuum levels during operation, the first chamber 10 for optics is normally maintained at a higher pressure than the second chamber 20 for substrate table. This is because the optics should be kept as clean as possible, while the second chamber 20 for substrate table is normally a source of unwanted molecules contaminations (e.g. out-gassing from resist, particles generated due to movable parts like wafer stages).
• the first chamber 10 may be purged (although the pressure of the chamber is very low) with a certain gas (e.g. hydrogen, nitrogen, helium or carbon dioxide) to keep optical elements for the projection system PS clean.
• a certain gas e.g. hydrogen, nitrogen, helium or carbon dioxide
• the pressure difference between the chambers 10, 20 generates a gas-flow (not shown in the Figure) directed from the first chamber 10 for optics towards the second chamber 20 for substrate table so as to prevent contaminations from entering the first chamber 10 for the optics during the operation of the apparatus.
• Figure 3 a, 3b and 3c schematically depict a non-limiting embodiment of the lithographic apparatus of Figure 1.
• the substrate table WT is positioned under the opening 30 (DGL).
• travel distance of the contaminations from the second chamber 20 for substrate table into the first chamber 10 for optics is relatively long (as shown with dotted allows). Therefore, the chance that contaminations in the second chamber 20 for substrate table will enter the first chamber 10 for optics is negligibly small, because there is a correlation between the travel distance of the contaminations and the chance of such contamination to enter into the first chamber 10 for the projection system PS.
• a closing device 40 may be applied to the opening 30, as shown in Figure 3 c.
• the closing device 40 which moves into the position under the opening 30 DGL, increases the travel distance for contaminations.
• the closing device 40 should not completely close the opening 30 (DGL), because the completion of the closure of the shared opening 30 (DGL) may cause throughput loss due to the pressure difference between the chambers 10, 20, which may cause the closing device 40 to "strongly stick" to the wall separating the chambers 10, 20.
• the opening 30 were to completely close, the pressure of the first chamber 10 would increase due to the purged gas, while the second chamber 20 would be maintained at a low pressure. Then, if the closing device 40 were to be opened under this circumstance, a strong gas current would be generated due to the large pressure difference between the chambers 10, 20, and the current would effectively stir up contaminations in the second chamber 20. The effect may even make the first chamber 10 dirtier than without the closing device 40.
• Figure 4 schematically depicts a lithographic apparatus according to a non-limiting embodiment of the invention.
• the closing device 40 discussed with respect to Figure 3c is located not “under” the opening 30 but “inside” the opening 30.
• the closing device 40 may be "above” the opening (not shown in the Figure) to achieve the same effect.
• This embodiment may be beneficial because there is no extra space needed for the mechanism of the closing device 40.
• the distance between the opening 40 to the top surface of the substrate table WT is in the order of a millimeter.
• to make a space for such a closing device may create challenges, which may be solved by this approach.
• FIG. 5 schematically depicts a lithographic apparatus according to an non-limiting embodiment of the invention.
• a closing device 50 configured to close the opening 30 (DGL) while keeping the gas-flow capability is not a plate-like structure.
• the closing device 50 of Figure 5 is a cone-like structure that complements the cone-like structure of the opening 30 (DGL).
• the closing device of embodiments of the present invention is not limited to a plate, but may have any shape that allows the opening 30 to be substantially closed, while still allowing gas flow between the first chamber 10 and the second chamber 20.
• Such a closing device 50 may be advantageous because of its efficiency to increase the travel distance of the contaminations in the second chamber 20 to enter the firs chamber 10.
• the closing device may have a lot of small trough-holes that are not straight through, but meander so as to enlarge the travel distance (travel length for contaminations).
• specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin-film magnetic heads, etc.
• any use of the terms "wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or “target portion”, respectively.
• the substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and/or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.
• imprint lithography a topography in a patterning device defines the pattern created on a substrate.
• the topography of the patterning device may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof.
• the patterning device is moved out of the resist leaving a pattern in it after the resist is cured.
• UV radiation e.g. having a wavelength of or about 365, 355, 248, 193, 157 or 126 nm
• EUV radiation e.g. having a wavelength in the range of 5-20 nm
• particle beams such as ion beams or electron beams.
• lens may refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic and electrostatic optical components.
• the invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g. semiconductor memory, magnetic or optical disk) having such a computer program stored therein.
• a data storage medium e.g. semiconductor memory, magnetic or optical disk

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• 2009
  • 2009-02-12 NL NL1036566A patent/NL1036566A1/nl active Search and Examination
  • 2009-03-26 WO PCT/EP2009/002211 patent/WO2009124660A1/en active Application Filing
  • 2009-03-27 TW TW098110317A patent/TWI463268B/zh not_active IP Right Cessation

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