Patent Application
20070267995
The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:
When a stage such as a reticle stage has the capability to move in up to six degrees of freedom, the accuracy with which a reticle may be positioned is enhanced. In many stage systems, however, providing the capability for a stage to move in a z-direction is often difficult due to space constraints.
Utilizing a carrier stage with three degrees of freedom, e.g., two translational degrees of freedom and one rotational degree of freedom, to carry an actuator arrangement and to support a monolithic fine stage enables the monolithic fine stage to have up to six degrees of freedom. Cables and hoses associated with the actuator arrangement may be a part of the carrier stage, and the carrier stage may be used to provide three degrees of freedom to the monolithic fine stage, while a second actuator arrangement preferably attached to a countermass may be used to provide another three degrees of freedom to the monolithic fine stage.
Carrier stages 108a, 108b are arranged over a countermass 112. Countermass 112 typically is allowed to move along an x-axis 120a, along y-axis 120b, and about a z-axis 120c. A base frame arrangement 116 is arranged substantially beneath countermass 112 to support countermass 112 and carrier stages 108a, 108b.
With reference to
Although motor arrangement 201a and motor arrangement 201b are offset from one another relative to z-axis 120, it should be appreciated that motor arrangement 201a and motor arrangement 201b may instead be aligned with each other relative to z-axis 120. Typically, motor arrangement 201a and motor arrangement 201b are arranged such that net forces applied by motor arrangement 201a and motor arrangement 201b effectively push through a center of gravity 207 of reticle stage 104.
Each carrier stage 108a, 108b is arranged to move over base arrangement 116 of
Referring next to
In addition to masses 422 and flexures 426, countermass 112 also includes stators for actuators that provide translation movements within stage apparatus 100 of
Trim motor portions 542 are arranged to provide, in cooperation with trim motor portions 434 of
As shown in
A Z actuator that is carried on a carrier stage, e.g., Z actuator 310 of
Z actuator 810 includes a VCM 852, an antigravity arrangement 860, and an air bearing arrangement 858. Z actuator 810 also includes a base 862 that is arranged to be coupled to a surface such as a surface of a carrier stage (not shown). Air bearing arrangement 858 is arranged to support a structure such as a reticle fine stage. Z actuator 810 also includes a tilting flexure (not shown). The tilting flexure is arranged to allow a reticle fine stage to rotate about an x-direction and a y-direction. In general, Z actuator 810 includes a mover component and a stator component.
A tilting flexure 870 is positioned between air bearing arrangement 858 and magnet 852a. A guide shaft 874 extends through an interior of mover 864 and is arranged to be positioned in an air bushing guide (not shown) of a stator. Guide shaft 874 allows mover 864 to be aligned with the stator.
The design of a stage apparatus which uses a carrier stage with three degrees of freedom to carry a monolithic stage such that the monolithic stage has up to six degrees of freedom may vary.
Monolithic stage 904 is generally a fine stage that provides fine positioning, and carrier stage 908 is generally a lower accuracy stage that supports fine stage 904. In one embodiment, monolithic stage 904 is a reticle stage or a reticle holder that supports a reticle 911.
Drive actuators 901 are arranged to drive monolithic stage 904 at least along a y-axis 920b. Typically, drive actuators 901 drive monolithic stage 904 along both y-axis 920b and an x-axis 920a. Z actuators 910 are carried on carrier stage 908, and allow monolithic stage 904 to move relative to a z-axis 920c. Stage system 900 may include three or more Z actuators 910 such that monolithic stage 904 may translate relative to z-axis 920c, and rotate relative to x-axis 920a and y-axis 920b using Z actuators 910. Carrier stage 908 is driven by actuators 918 along y-axis 920b. A yaw guide 990 is arranged to constrain carrier stage 908 from moving along x-axis 920a or rotating about z-axis 920c. Typically, actuators 901, 918 may be coupled between fine stage 904 and carrier stage 908 and a countermass (not shown).
With reference to
The orientation of Z actuators, or an actuator arrangement, supported on a carrier stage, may vary depending on the requirements of a particular system. That is, specifications associated with a given stage apparatus may determine how actuators carried on a carrier stage are arranged.
Z actuators 1010 are positioned beneath a fine stage 1004 such that fine stage 1004 may rotate about an x-axis 1020a and about y-axis 1020b, and translate along a z-axis 1020c. Fine stage 1004 includes motor arrangements 1001a, 1001b that drive fine stage 1004 along x-axis 1020a, y-axis 1020b, and about z-axis 1020c. It should be understood that portions of actuators 1018 and motor arrangements 1001a, 1001b may be included in a countermass (not shown).
Z actuators 1110 are positioned beneath a fine stage 1104. Using Z actuators 1110, fine stage 1104 may rotate about an x-axis 1102a, rotate about y-axis 1102b, and translate along a z-axis 1102c. Fine stage 1104 includes motor arrangements 1101a, 1101b that drive fine stage 1104 along x-axis 1120a, y-axis 1120b, and about z-axis 1120c.
Referring next to
Wafer table 51 may be levitated in a z-direction 10b by any number of VCMs (not shown), e.g., three voice coil motors. In one embodiment, at least three magnetic bearings (not shown) couple and move wafer table 51 along a y-axis 10a along x-axis 10c and about z-axis 10b. The motor array of wafer positioning stage 52 is typically supported by a base 70. Base 70 is supported to a ground via isolators 54. Reaction forces generated by motion of wafer stage 52 may be mechanically released to a ground surface through a frame 66. One suitable frame 66 is described in JP Hei 8-166475 and U.S. Pat. No. 5,528,118, which are each herein incorporated by reference in their entireties.
An illumination system 42 is supported by a frame 72. Frame 72 is supported to the ground via isolators 54. Frame 72 may be part of a lens mount system of illumination system 42, and may be coupled to an active damper (not shown) which damps vibrations in frame 72 and, hence, illumination system 42. Illumination system 42 includes an illumination source, and is arranged to project a radiant energy, e.g., light, through a mask pattern on a reticle 68 that is supported by and scanned using a reticle stage 44 which includes a carrier stage and a fine stage, as described above. The radiant energy is focused through projection optical system 46, which is supported on a projection optics frame 50 and may be supported the ground through isolators 54. Suitable isolators 54 include those described in JP Hei 8-330224 and U.S. Pat. No. 5,874,820, which are each incorporated herein by reference in their entireties.
A first interferometer 56 is supported on projection optics frame 50, and functions to detect the position of wafer table 51. Interferometer 56 outputs information on the position of wafer table 51 to system controller 62. A second interferometer 58 is supported on projection optics frame 50, and detects the position of reticle stage 44 which supports a reticle 68. Interferometer 58 also outputs position information to system controller 62.
It should be appreciated that there are a number of different types of photolithographic apparatuses or devices. For example, photolithography apparatus 40, or an exposure apparatus, may be used as a scanning type photolithography system which exposes the pattern from reticle 68 onto wafer 64 with reticle 68 and wafer 64 moving substantially synchronously. In a scanning type lithographic device, reticle 68 is moved perpendicularly with respect to an optical axis of a lens assembly (projection optical system 46) or illumination system 42 by reticle stage 44. Wafer 64 is moved perpendicularly to the optical axis of projection optical system 46 by a wafer positioning stage 52. Scanning of reticle 68 and wafer 64 generally occurs while reticle 68 and wafer 64 are moving substantially synchronously.
Alternatively, photolithography apparatus or exposure apparatus 40 may be a step-and-repeat type photolithography system that exposes reticle 68 while reticle 68 and wafer 64 are stationary, i.e., at a substantially constant velocity of approximately zero meters per second. In one step and repeat process, wafer 64 is in a substantially constant position relative to reticle 68 and projection optical system 46 during the exposure of an individual field. Subsequently, between consecutive exposure steps, wafer 64 is consecutively moved by wafer positioning stage 52 perpendicularly to the optical axis of projection optical system 46 and reticle 68 for exposure. Following this process, the images on reticle 68 may be sequentially exposed onto the fields of wafer 64, and then that the next field of semiconductor wafer 64 is brought into position relative to illumination system 42, reticle 68, and projection optical system 46.
It should be understood that the use of photolithography apparatus or exposure apparatus 40, as described above, is not limited to being used in a photolithography system for semiconductor manufacturing. For example, photolithography apparatus 40 may be used as a part of a liquid crystal display (LCD) photolithography system that exposes an LCD device pattern onto a rectangular glass plate or a photolithography system for manufacturing a thin film magnetic head.
The illumination source of illumination system 42 may be g-line (436 nanometers (nm)), i-line (365 nm), a KrF excimer laser (248 nm), an ArF excimer laser (193 nm), and an F2-type laser (157 nm). Alternatively, illumination system 42 may also use charged particle beams such as x-ray and electron beams. For instance, in the case where an electron beam is used, thermionic emission type lanthanum hexaboride (LaB6) or tantalum (Ta) may be used as an electron gun. Furthermore, in the case where an electron beam is used, the structure may be such that either a mask is used or a pattern may be directly formed on a substrate without the use of a mask.
With respect to projection optical system 46, when far ultra-violet rays such as an excimer laser is used, glass materials such as quartz and fluorite that transmit far ultra-violet rays is preferably used. When either an F2-type laser or an x-ray is used, projection optical system 46 may be either catadioptric or refractive (a reticle may be of a corresponding reflective type), and when an electron beam is used, electron optics may comprise electron lenses and deflectors. As will be appreciated by those skilled in the art, the optical path for the electron beams is generally in a vacuum.
In addition, with an exposure device that employs vacuum ultra-violet (VUV) radiation of a wavelength that is approximately 200 nm or lower, use of a catadioptric type optical system may be considered. Examples of a catadioptric type of optical system include, but are not limited to, those described in Japan Patent Application Disclosure No. 8-171054 published in the Official gazette for Laid-Open Patent Applications and its counterpart U.S. Pat. No. 5,668,672, as well as in Japan Patent Application Disclosure No. 10-20195 and its counterpart U.S. Pat. No. 5,835,275, which are all incorporated herein by reference in their entireties. In these examples, the reflecting optical device may be a catadioptric optical system incorporating a beam splitter and a concave mirror. Japan Patent Application Disclosure (Hei) No. 8-334695 published in the Official gazette for Laid-Open Patent Applications and its counterpart U.S. Pat. No. 5,689,377, as well as Japan Patent Application Disclosure No. 10-3039 and its counterpart U.S. Pat. No. 5,892,117, which are all incorporated herein by reference in their entireties. These examples describe a reflecting-refracting type of optical system that incorporates a concave mirror, but without a beam splitter, and may also be suitable for use with the present invention.
The present invention may be utilized, in one embodiment, in an immersion type exposure apparatus if suitable measures are taken to accommodate a fluid. For example, PCT patent application WO 99/49504, which is incorporated herein by reference in its entirety, describes an exposure apparatus in which a liquid is supplied to a space between a substrate (wafer) and a projection lens system during an exposure process. Aspects of PCT patent application WO 99/49504 may be used to accommodate fluid relative to the present invention.
Further, the present invention may be utilized in an exposure apparatus that comprises two or more substrate and/or reticle stages. In such an apparatus, e.g., an apparatus with two substrate stages, one substrate stage may be used in parallel or preparatory steps while the other substrate stage is utilizes for exposing. Such a multiple stage exposure apparatus is described, for example, in Japan patent Application Disclosure No. 10-163099, as well as in Japan patent Application Disclosure No. 10-214783 and its U.S. counterparts, namely U.S. Pat. No. 6,341,007, U.S. Pat. No. 6,400,441, U.S. Pat. No. 6,549,269, U.S. Pat. No. 6,590,634. Each of these Japan patent Application Disclosures and U.S. patents are incorporated herein by reference in their entireties. A multiple stage exposure apparatus is also described in Japan patent Application Disclosure No. 20000-505958 and its counterparts U.S. Pat. No. 5,969,441 and U.S. Pat. No. 6,208,407, each of which are incorporated herein by reference in their entireties.
The present invention may be utilized in an exposure apparatus that has a movable stage that retains a substrate (wafer) for exposure, as well as a stage having various sensors or measurement tools, as described in Japan patent Application Disclosure No. 11-135400, which is incorporated herein by reference in its entirety. In addition, the present invention may be utilized in an exposure apparatus that is operated in a vacuum environment such as an EB type exposure apparatus and a EUVL type exposure apparatus when suitable measures are incorporated to accommodate the vacuum environment for air (fluid) bearing arrangements.
Further, in photolithography systems, when linear motors (see U.S. Pat. Nos. 5,623,853 or 5,528,118, which are each incorporated herein by reference in their entireties) are used in a wafer stage or a reticle stage, the linear motors may be either an air levitation type that employs air bearings or a magnetic levitation type that uses Lorentz forces or reactance forces. Additionally, the stage may also move along a guide, or may be a guideless type stage which uses no guide.
Alternatively, a wafer stage or a reticle stage may be driven by a planar motor which drives a stage through the use of electromagnetic forces generated by a magnet unit that has magnets arranged in two dimensions and an armature coil unit that has coil in facing positions in two dimensions. With this type of drive system, one of the magnet unit or the armature coil unit is connected to the stage, while the other is mounted on the moving plane side of the stage.
Movement of the stages as described above generates reaction forces which may affect performance of an overall photolithography system. Reaction forces generated by the wafer (substrate) stage motion may be mechanically released to the floor or ground by use of a frame member as described above, as well as in U.S. Pat. No. 5,528,118 and published Japanese Patent Application Disclosure No. 8-166475. Additionally, reaction forces generated by the reticle (mask) stage motion may be mechanically released to the floor (ground) by use of a frame member as described in U.S. Pat. No. 5,874,820 and published Japanese Patent Application Disclosure No. 8-330224, which are each incorporated herein by reference in their entireties.
Isolaters such as isolators 54 may generally be associated with an active vibration isolation system (AVIS). An AVIS generally controls vibrations associated with forces, i.e., vibrational forces, which are experienced by a stage assembly or, more generally, by a photolithography machine such as photolithography apparatus 40 which includes a stage assembly.
A photolithography system according to the above-described embodiments may be built by assembling various subsystems in such a manner that prescribed mechanical accuracy, electrical accuracy, and optical accuracy are maintained. In order to maintain the various accuracies, prior to and following assembly, substantially every optical system may be adjusted to achieve its optical accuracy. Similarly, substantially every mechanical system and substantially every electrical system may be adjusted to achieve their respective desired mechanical and electrical accuracies. The process of assembling each subsystem into a photolithography system includes, but is not limited to, developing mechanical interfaces, electrical circuit wiring connections, and air pressure plumbing connections between each subsystem. There is also a process where each subsystem is assembled prior to assembling a photolithography system from the various subsystems. Once a photolithography system is assembled using the various subsystems, an overall adjustment is generally performed to ensure that substantially every desired accuracy is maintained within the overall photolithography system. Additionally, it may be desirable to manufacture an exposure system in a clean room where the temperature and humidity are controlled.
Further, semiconductor devices may be fabricated using systems described above, as will be discussed with reference to
At each stage of wafer processing, when preprocessing steps have been completed, post-processing steps may be implemented. During post-processing, initially, in step 1315, photoresist is applied to a wafer. Then, in step 1316, an exposure device may be used to transfer the circuit pattern of a reticle to a wafer. Transferring the circuit pattern of the reticle of the wafer generally includes scanning a reticle scanning stage. It should be appreciated that when the circuit pattern of the reticle is transferred to the wafer, an automatic reticle blind is generally in an open position to allow a laser beam to pass therethrough.
After the circuit pattern on a reticle is transferred to a wafer, the exposed wafer is developed in step 1317. Once the exposed wafer is developed, parts other than residual photoresist, e.g., the exposed material surface, may be removed by etching in step 1318. Finally, in step 1319, any unnecessary photoresist that remains after etching may be removed. As will be appreciated by those skilled in the art, multiple circuit patterns may be formed through the repetition of the preprocessing and post-processing steps.
Although only a few embodiments of the present invention have been described, it should be understood that the present invention may be embodied in many other specific forms without departing from the spirit or the scope of the present invention. By way of example, the configuration of motor arrangements that drive a fine stage along horizontal axes may vary. Further, the alignment of such motor arrangements may also vary. As described above, motor arrangements which drive a fine stage along an x-axis and a y-axis may be aligned in substantially any manner that enables the fine stage to be driven through a center of gravity.
While a fine stage has been described as being a reticle stage, a fine stage may instead be a wafer stage, i.e., a stage that supports a wafer. Further, a reticle stage may not necessarily be a fine stage, e.g., stage 104 of
The number of actuators in a stage apparatus may vary widely. By way of example, more than three Z actuators may be supported on a carrier stage arrangement. Further, the number of motor arrangements that drive a fine stage along a horizontal axis may vary. Separate actuators may provide movement along each horizontal axis, i.e., a motor arrangement may not necessarily be a combined actuator that is capable of providing translational movement along more than one axis. In one embodiment, a fine stage may be driven by approximately four 3-phase motors along a y-axis, and by one VCM in an x-direction.
Stators associated with motors which allow a carrier stage to be driven and controlled may generally be considered to be part of a countermass frame. That is, a countermass may include the mass associated with motor stators. As previously mentioned, a countermass may have a variety of different configurations. Therefore, the present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope of the appended claims.
This application claims priority of U.S. Provisional Patent Application No. 60/747,556, filed May 18, 2006, which is incorporated herein by reference in its entirety. The present invention is also related to co-pending U.S. patent application Ser. No. 11/750,545, filed May 18, 2007 (Atty. Docket No. NRCAP037/PAO-720), which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60747556 | May 2006 | US |
