Patent Application
20080073563
The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:
As provided herein, one or both of the stage assemblies 18, 20 can include a mover combination 26 having one or more movers 28 and one or more circulation systems 30 (illustrated as a box in
A number of Figures include an orientation system that illustrates an X axis, a Y axis that is orthogonal to the X axis and a Z axis that is orthogonal to the X and Y axes. It should be noted that these axes can also be referred to as the first, second and third axes.
The exposure apparatus 10 is particularly useful as a lithographic device that transfers a pattern (not shown) of an integrated circuit from a reticle 32 onto a semiconductor wafer 34. The exposure apparatus 10 mounts to a mounting base 36, e.g., the ground, a base, or floor or some other supporting structure.
There are a number of different types of lithographic devices. For example, the exposure apparatus 10 can be used as a scanning type photolithography system that exposes the pattern from the reticle 32 onto the wafer 34 with the reticle 32 and the wafer 34 moving synchronously. In a scanning type lithographic device, the reticle 32 is moved perpendicularly to an optical axis of the optical assembly 16 by the reticle stage assembly 18 and the wafer 34 is moved perpendicularly to the optical axis of the optical assembly 16 by the wafer stage assembly 20. Scanning of the reticle 32 and the wafer 34 occurs while the reticle 32 and the wafer 34 are moving synchronously.
Alternatively, the exposure apparatus 10 can be a step-and-repeat type photolithography system that exposes the reticle 32 while the reticle 32 and the wafer 34 are stationary. In the step and repeat process, the wafer 34 is in a constant position relative to the reticle 32 and the optical assembly 16 during the exposure of an individual field. Subsequently, between consecutive exposure steps, the wafer 34 is consecutively moved with the wafer stage assembly 20 perpendicularly to the optical axis of the optical assembly 16 so that the next field of the wafer 34 is brought into position relative to the optical assembly 16 and the reticle 32 for exposure. Following this process, the images on the reticle 32 are sequentially exposed onto the fields of the wafer 34, and then the next field of the wafer 34 is brought into position relative to the optical assembly 16 and the reticle 32.
However, the use of the exposure apparatus 10 provided herein is not limited to a photolithography system for semiconductor manufacturing. The exposure apparatus 10, for example, can be used as an LCD photolithography system that exposes a liquid crystal display device pattern onto a rectangular glass plate or a photolithography system for manufacturing a thin film magnetic head. Further, the present invention can also be applied to a proximity photolithography system that exposes a mask pattern from a mask to a substrate with the mask located close to the substrate without the use of a lens assembly.
The apparatus frame 12 is rigid and supports the components of the exposure apparatus 10. The apparatus frame 12 illustrated in
In one embodiment, the illumination system 14 includes an illumination source 38 and an illumination optical assembly 40. The illumination source 38 emits a beam (irradiation) of light energy. The illumination optical assembly 40 guides the beam of light energy from the illumination source 38 to the optical assembly 16. The beam illuminates selectively different portions of the reticle 32 and exposes the wafer 34. In
The illumination source 38 can be a g-line source (436 nm), an i-line source (365 nm), a KrF excimer laser (248 nm), an ArF excimer laser (193 nm) or a F2 laser (157 nm). Alternatively, the illumination source 38 can generate charged particle beams such as an x-ray or an electron beam. For instance, in the case where an electron beam is used, thermionic emission type lanthanum hexaboride (LaB6) or tantalum (Ta) can be used as a cathode for an electron gun. Furthermore, in the case where an electron beam is used, the structure could be such that either a mask is used or a pattern can be directly formed on a substrate without the use of a mask.
The optical assembly 16 projects and/or focuses the light passing through the reticle 32 to the wafer 34. Depending upon the design of the exposure apparatus 10, the optical assembly 16 can magnify or reduce the image illuminated on the reticle 32. The optical assembly 16 need not be limited to a reduction system. It could also be a 1× or magnification system.
When far ultra-violet rays such as the excimer laser is used, glass materials such as quartz and fluorite that transmit far ultra-violet rays can be used in the optical assembly 16. When the F2 type laser or x-ray is used, the optical assembly 16 can be either catadioptric or refractive (a reticle should also preferably be a reflective type), and when an electron beam is used, electron optics can consist of electron lenses and deflectors. The optical path for the electron beams should be in a vacuum.
Also, with an exposure device that employs vacuum ultra-violet radiation (VUV) of wavelength 200 nm or lower, use of the catadioptric type optical system can be considered. Examples of the catadioptric type of optical system include the disclosure 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 Japan Patent Application Disclosure No. 10-20195 and its counterpart U.S. Pat. No. 5,835,275. In these cases, the reflecting optical device can be a catadioptric optical system incorporating a beam splitter and concave mirror. Japan Patent Application Disclosure 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. Patent Application No. 873,605 (Application Date: Jun. 12, 1997) also use a reflecting-refracting type of optical system incorporating a concave mirror, etc., but without a beam splitter, and can also be employed with this invention. As far as is permitted, the disclosures in the above-mentioned U.S. patents, as well as the Japan patent applications published in the Official Gazette for Laid-Open Patent Applications are incorporated herein by reference.
The reticle stage assembly 18 holds and positions the reticle 32 relative to the optical assembly 16 and the wafer 34. Somewhat similarly, the wafer stage assembly 20 holds and positions the wafer 34 with respect to the projected image of the illuminated portions of the reticle 32. The design of each stage assembly 18, 20 can be varied to suit the movement requirements of the exposure apparatus 10. In
Somewhat similarly, the wafer stage assembly 20 includes a wafer stage 46 that retains the wafer 34 and a wafer mover assembly 48 that moves and positions the wafer stage 46 and the wafer 34 relative to the rest of the exposure apparatus 10. For example, the wafer mover assembly 48 can include one or more movers 28 and can be designed to move the wafer stage 46 with three degrees of freedom of movement. Alternatively, the wafer mover assembly 48 can be designed to move the wafer stage 46 with more than three or less than three degrees of freedom of movement.
When linear motors (see U.S. Pat. Nos. 5,623,853 or 5,528,118) are used in a wafer stage or a mask stage, the linear motors can be either an air levitation type employing air bearings or a magnetic levitation type using Lorentz force or reactance force. As far as is permitted, the disclosures in U.S. Pat. Nos. 5,623,853 and 5,528,118 are incorporated herein by reference.
Alternatively, one or both of the stages could be driven by a planar motor, which drives the stage by an electromagnetic force generated by a magnet unit having two-dimensionally arranged magnets and an armature coil unit having two-dimensionally arranged coils in facing positions. With this type of driving system, either the magnet unit or the armature coil unit is connected to the stage and the other unit is mounted on the moving plane side of the stage.
Movement of the stages as described above generates reaction forces that can affect performance of the photolithography system. Reaction forces generated by the wafer (substrate) stage motion can be mechanically transferred to the floor (ground) by use of a frame member as described in U.S. Pat. No. 5,528,100 and published Japanese Patent Application Disclosure No. 8-136475. Additionally, reaction forces generated by the reticle (mask) stage motion can be mechanically transferred 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. As far as is permitted, the disclosures in U.S. Pat. Nos. 5,528,100 and 5,874,820 and Japanese Patent Application Disclosure No. 8-330224 are incorporated herein by reference.
The measurement system 22 monitors movement of (i) the reticle stage 42 and the reticle 32 relative to the optical assembly 16 or some other reference, and (ii) the wafer stage 46 and the wafer 34 relative to the optical assembly 16 or some other reference. With this information, the control system 24 can control the reticle stage assembly 18 to precisely position the reticle 32 and the wafer stage assembly 20 to precisely position the wafer 34. For example, the measurement system 22 can utilize multiple laser interferometers, encoders, and/or other measuring devices.
The control system 24 is electrically connected to the reticle stage assembly 18, the wafer stage assembly 20, the measurement system 22, and the one or more circulation systems 30. The control system 24 receives information from the measurement system 22 and controls the stage assemblies 18, 20 to precisely position the reticle 32 and the wafer 34. Further, the control system 24 controls the operation of the one or more circulation systems 30. The control system 24 can include one or more processors and circuits.
Additionally, the exposure apparatus 10 can include one or more isolation systems that include a mover combination 26 having features of the present invention. For example, in
A photolithography system (an exposure apparatus) according to the embodiments described herein can be built by assembling various subsystems, including each element listed in the appended claims, 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, every optical system is adjusted to achieve its optical accuracy. Similarly, every mechanical system and every electrical system are adjusted to achieve their respective mechanical and electrical accuracies. The process of assembling each subsystem into a photolithography system includes 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, a total adjustment is performed to make sure that accuracy is maintained in the complete photolithography system. Additionally, it is desirable to manufacture an exposure system in a clean room where the temperature and cleanliness are controlled.
This invention can be utilized in an immersion type exposure apparatus with taking suitable measures for a liquid. For example, PCT Patent Application WO 99/49504 discloses an exposure apparatus in which a liquid is supplied to the space between a substrate (wafer) and a projection lens system in exposure process. As far as is permitted, the disclosures in WO 99/49504 are incorporated herein by reference.
Further, this invention can be utilized in an exposure apparatus that comprises two or more substrate and/or reticle stages. In such apparatus, the additional stage may be used in parallel or preparatory steps while the other stage is being used for exposing. Such a multiple stage exposure apparatus are described, for example, in Japan Patent Application Disclosure No. 10-163099 as well as Japan Patent Application Disclosure No. 10-214783 and its counterparts U.S. Pat. No. 6,341,007, No. 6,400,441, No. 6,549,269, and No. 6,590,634. Also it is described in Japan Patent Application Disclosure No. 2000-505958 and its counterparts U.S. Pat. No. 5,969,411 as well as U.S. Pat. No. 6,208,407. As far as is permitted, the disclosures in the above-mentioned U.S. Patents, as well as the Japan Patent Applications, are incorporated herein by reference.
This invention can be utilized in an exposure apparatus that has a movable stage retaining a substrate (wafer) for exposing it, and a stage having various sensors or measurement tools for measuring, as described in Japan Patent Application Disclosure 11-135400. As far as is permitted, the disclosures in the above-mentioned Japan patent application are incorporated herein by reference.
In
The magnet component 260 includes one or more spaced apart magnet arrays 264 (illustrated in phantom). For example, in
Additionally, the mover 328 defines a fluid passageway 370 that can be used to cool and/or control the temperature of the conductor array 366 or another portion of the mover 328. The design and location of the fluid passageway 370 can be varied to achieve the desired cooling requirements of the mover 328. In one embodiment, the fluid passageway 370 is positioned near the conductor array 366. In
As provided herein, the fluid passageway 370 includes one or more passageway inlets 374 and one or more passageway outlets 376 that are in fluid communication with the circulation system 330. With this design, in certain embodiments, the circulation system 330 directs a circulation fluid 378 into the fluid passageway 370 via the one or more passageway inlets 374, and the circulation fluid 378 that passes through the fluid passageway 370 exits the one or more passageway outlets 376 to the circulation system 330. It should be noted that the location of the passageway inlet(s) 374 and/or passageway outlet(s) 376 can be varied to influence the cooling of the conductor array 366. In the embodiment illustrated in
In certain embodiments, the circulation system 330 can be used to maintain a portion of the entire outer surface of the mover 328 at a set temperature, and/or to reduce the amount of heat transferred from the mover 328 to the surrounding environment. This reduces the influence of the mover 328 on the temperature of the environment surrounding the mover 328 and allows for more accurate positioning by the mover 328.
The design of the circulation system 330 can vary. In one embodiment, the circulation fluid 378 can be used to cool the conductor component 362 without increasing the temperature of the circulation fluid 378 by using latent heat based on changes in a state of the circulation fluid 378. In certain embodiments, the circulation system 330 controls the temperature of the circulation fluid 378 at or near the passageway inlet 374 and the pressure of the circulation fluid 378 at or near the passageway outlet 376 so that (i) the circulation fluid 378 is primarily a liquid 378A (illustrated as small squares) at the passageway inlet 374, and (ii) the temperature of the circulation fluid 378 at the passageway outlet 376 is approximately equal to the temperature of the circulation fluid 378 at the passageway inlet 374. In alternative, non-exclusive embodiments, the circulation system 330 controls the temperature and pressure of the circulation fluid 378 so that at least approximately 95, 97, 98, 99 or 100 percent of the circulation fluid 378 is a liquid 378A at the passageway inlet 374. Further, the circulation system 330 controls the temperature and pressure of the circulation fluid 378 so that the circulation fluid 378 is near the boiling point without boiling at the passageway inlet 374. For example, in alternative, non-exclusive embodiments, the circulation system 330 controls the temperature and pressure of the circulation fluid 378 so that the circulation fluid 378 is within approximately 2, 1, 0.8, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 degrees Celsius of the boiling temperature of the circulation fluid 378 at the absolute pressure at the passageway inlet 374. Moreover, the pressure control device 388 controls the pressure of the circulation fluid 378 near the passageway outlet 376 so that the temperature of the circulation fluid 378 at the passageway outlet 376 is within approximately 1, 0.8, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 degrees Celsius of the temperature of the circulation fluid 378 at the passageway inlet 374.
Additionally, as detailed below, at least a portion of the circulation fluid 378 undergoes a phase change during movement through the fluid passageway 370. In one embodiment, at least a portion of the circulation fluid 378 changes phase from a liquid 378A to a gas 378B (illustrated as small circles) during movement through the fluid passageway 370.
In one embodiment, the circulation fluid 378 is a substantially inactive (e.g., inert) fluid. For example, hydrofluoroether (e.g., “Novec HFE”: manufactured by 3M, Minneapolis, Minn.), a fluoride system inactive liquid (e.g., “Flourinert” manufactured by 3M, Minneapolis, Minn.), or the like, can be used or water also can be used as a circulation substance.
In
It should also be noted that one or more of the components of the circulation system 330 can be controlled by the control system 24 (illustrated in
The pump assembly 380 moves the circulation fluid 378 through the circulation system 330 and the fluid passageway 370. In
The temperature adjusting device 382 adjusts the temperature of the circulation fluid 378 in the circulation system 330. In
The separator 384 separates gas 378B from the liquid 378A of the circulation fluid 378. With the use of the separator 384, only the gas 378B is directed to the condenser 390. As a result thereof, in certain embodiments, the plumbing for the liquid 378A and the gas 378B that exits the fluid passageway 370 can each be optimized.
The design and location of the separator 384 can be varied to achieve the requirements of the circulation system 330. Suitable gas/liquid separators 384 include a chamber with two outlet ports, namely a vapor remove port and liquid remove port, the vapor remove port being physically at a higher location than the liquid remove port. In this embodiment, the working of the separator is based on using gravity to separate lighter vapor from heavier liquid drops. The vapor which is lighter rises into the upper portion of the chamber and the liquid which is heavier will be on the lower portion of the chamber.
In one embodiment, the separator 384 is secured to the conductor component 362 and moves with the conductor component 362. In
Alternatively, the separator 384 can be spaced apart from the conductor component 362 and/or the conductor component 362 can move relative to the separator 384. In this design, the passageway outlet 376 is still in fluid communication with the inlet of the separator 382.
The level maintainer 386 maintains a predetermined level of liquid 378A within the fluid passageway 370. With this design, in certain embodiments, the level maintainer 386 ensures that all of the conductors 368 are at least partly submerged with the liquid 378A. A suitable level maintainer 386 is illustrated in
The pressure control device 388 precisely controls the pressure of the circulation fluid 378 in at least a portion of the fluid passageway 370 to precisely control the temperature of the circulation fluid 378 at or near the passageway outlet 376. In certain embodiments, the pressure control device 388 precisely controls the pressure of the circulation fluid 378 at or near the passageway outlet 376. With this design, the pressure control device 388 can adjust the pressure of the circulation fluid 378 at or near the passageway outlet 376 so that the temperature of the circulation fluid 378 at the passageway outlet 376 is approximately equal to the temperature of the circulation fluid 378 at the passageway inlet 374. With this design, the circulation fluid 378 can be used to maintain the mover 328 at a set temperature without increasing the temperature of the circulation fluid 378, and the influence of heat from the mover 328 on the surrounding environment is significantly reduced.
Alternatively, for example, the pressure control device 388 can be used to adjust the pressure of the circulation fluid 378 at or near the passageway outlet 376 so that the temperature of the circulation fluid 378 at the passageway outlet 376 is a predetermined amount (e.g. 1 degree Celsius) different than the temperature of the circulation fluid 378 at the passageway inlet 374.
Non-exclusive examples of suitable pressure control devices 388 can include an electronic regulator, a pump, or a variable volume chambers (e.g. bellows). The amount of pressure change that the pressure control device 388 makes on the circulation fluid 378 can be varied according to the type of circulation fluid 378, the design of the mover 328, and the design of the rest of the circulation system 330. In alternative, non-exclusive embodiments, the pressure control device 388 reduces the pressure of the circulation fluid 378 approximately 0.5, 1, 2, 3, 4, or 5 PSI.
The pressure control device 388 can be controlled either in an open-loop fashion or by using closed loop feedback control. The feedback can be from a temperature or pressure sensor 395 positioned at the point where temperature is to be regulated.
In
The condenser 390 receives the gas 378B from the separator 384 and condenses that gas 378B into liquid 378A with minimum deviation from the desired inlet temperature and is then transferred to the reservoir 392. In one embodiment, an inlet to the condenser 390 is in fluid communication with the gas outlet 384B of the separator 384. With this design, any gas 378B that leaves the separator 384 is condensed into liquid 378A. In one embodiment, the condenser 390 includes a heat exchanger that condenses the gas 378B into liquid 378A.
The reservoir 392 receives the liquid 378A from the separator 384 and the liquid 378A from the condenser 390. In one embodiment, a first inlet to the reservoir 392 is in fluid communication with the fluid exit of the level maintainer 386, and a second inlet to the reservoir 392 is in fluid communication with the exit of the condenser 390 via the pressure control device 388.
The operation of the circulation system 330 can be further explained with reference to
As illustrated in
It should be noted that the pressure of the circulation fluid 378 will change as the heat from the conductors 368 is transferred to the circulation fluid 378 and the circulation fluid 378 moves across the conductors 368. The pressure control device 388 can be used to compensate for the pressure change and to achieve the desired temperature of the circulation fluid 378 at the passageway outlet 376.
The left end of line Tp illustrates the inlet temperature Ti and the inlet pressure Pi of the circulation fluid 378 at the passageway inlet 374 (illustrated in
Stated in another fashion, as the circulation fluid 378 moves from the passageway inlet 374, the circulation fluid 378 first gains sensible heat from the conductors 368 (illustrated in
It should be noted that the inlet temperature Ti and the outlet temperature To are approximately equal to T1. However there is a slight variation in temperature in between Ti and To. More specifically, there is a slow rise in the temperature from state 1 to state 2 and a subsequent small drop in the temperature from state 2 to state 3. In certain embodiments, this temperature variation can be reduced by reducing the pressure drop from state 1 to state 2, and/or state 2 to state 3, leading to constant temperature heat removal from mover. Additionally, the appropriate choice of circulation fluid 378 can also help to reduce the variation in temperature.
Alternatively, the temperature variation can be reduced by either (i) adjusting the inlet temperature Ti to be different from desired mover temperature, (ii) adjusting the outlet pressure Po so that the liquid boils at a temperature different from desired mover temperature, (iii) by the appropriate design of the fluid passageway 370, (iv) by the appropriate design of the circulation system 330, and/or (iv) by using a combination of (i)-(iv).
In this embodiment, the pressure control device 588 is positioned between the separator 584 and the condenser 590. Further, the pressure control device 588 can be controlled to obtain similar functions as described in the previous embodiments.
In another embodiment, the amount of liquid supplied to the passageway inlet 574 can be regulated such that substantially all of the liquid is converted into gas at the passageway outlet 576. The gas coming out of the passageway outlet 576 may be saturated or superheated depending on temperature distribution requirements. With this design, the circulation system 530 can be designed without the separator 584 and a liquid outlet 584A.
In this embodiment, the circulation system 630 includes a pump assembly 680, a temperature adjusting device 682, a pair of separators 684, a pair of level maintainers 686, a pressure control device 688, a condenser 690, and a reservoir 692 that are somewhat similar to the corresponding components described above and illustrated in
In this embodiment, the circulation system 730 includes a pump assembly 780, a temperature adjusting device 782, a pair of separators 784, a pair of level maintainers 786, a pair of pressure control devices 788, a condenser 790, and a reservoir 792 that are somewhat similar to the corresponding components described above and illustrated in
In this embodiment, the circulation system 930 includes a pump assembly 980, a temperature adjusting device 982, a condenser 990, and a reservoir 992 that are somewhat similar to the corresponding components described above and illustrated in
In alternative, non-exclusive embodiments, the circulation system 930 controls the temperature and pressure of the circulation fluid 978 at the passageway inlet 974 so that at least approximately 95, 98, 99 or 100 percent of the circulation fluid 978 is a liquid 978A. Further, at least a portion of the circulation fluid 978 undergoes a phase change during movement through the fluid passageway 970. More specifically, at least a portion of the circulation fluid 978 changes from a liquid 978A to a gas 978B (illustrated as small circles) during movement through the fluid passageway 970.
In
Moreover, in
In this embodiment, the pressure control device 996 precisely adjusts the pressure of the circulation fluid 978, precisely controls the fluid state of the circulation fluid 978 at the passageway inlet 974, and brings the system to equilibrium with the proper fluid state at the passageway inlet 974. The temperature adjusting device precisely controls the temperature of fluid at inlet. Further, in one embodiment, the pressure control device 996 is at a location between the exit of the condenser 990 and the entrance to the reservoir assembly 980. With this design, the pressure control device 996 is acting on a single-phase circulation fluid 978.
The amount of pressure change that the pressure control device 996 makes on the circulation fluid 978 can be varied to achieve the desired fluid state of the circulation fluid 978. In alternative, non-exclusive embodiments, the pressure control device 996 decreases the pressure of the circulation fluid 978 at the passageway inlet 974 at least approximately 0.5, 1, 2, 3, 4, or 5 PSI. Stated another way, in alternative, non-exclusive embodiments, the pressure control device 996 decreases the pressure of the circulation fluid 978 at the passageway inlet 974 between approximately 0 and 1, 0 and 2, or 0 and 5 PSI.
In one embodiment, the passageway height 1000 is less than the passageway width 1002 and the passageway length 1004. Further, in one embodiment, the smallest dimension of the fluid passageway 1070 is positioned vertically and aligned with and coaxial with the force of gravity 1006, and the greatest dimension of the fluid passageway 1070 is positioned horizontally. In
Semiconductor devices can be fabricated using the above described systems, by the process shown generally in
At each stage of wafer processing, when the above-mentioned preprocessing steps have been completed, the following post-processing steps are implemented. During post-processing, first, in step 1115 (photoresist formation step), photoresist is applied to a wafer. Next, in step 1116 (exposure step), the above-mentioned exposure device is used to transfer the circuit pattern of a mask (reticle) to a wafer. Then in step 1117 (developing step), the exposed wafer is developed, and in step 1118 (etching step), parts other than residual photoresist (exposed material surface) are removed by etching. In step 1119 (photoresist removal step), unnecessary photoresist remaining after etching is removed. Multiple circuit patterns are formed by repetition of these preprocessing and post-processing steps.
While the current invention is disclosed in detail herein, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.
