System and method for controlling a temperature of a reaction assembly

A stage assembly (10) that includes (i) a stage (14) that retains a device (26); (ii) a reaction assembly (18) that is spaced apart from the stage (14); (iii) a stage mover (16) that moves the stage (14), the stage mover (16) including a magnet array (38) that is coupled to the stage (14) and a conductor array (36) that is coupled to the reaction assembly (18); (iv) a temperature adjuster (20); and (v) a control system (22) that selectively controls the temperature adjuster (20). The conductor array (36) includes a set of first zone conductor units (250), and a set of second zone conductor units (252). The temperature adjuster (20) independently adjusts the temperature of the set of first zone conductor units (250), and the set of second zone conductor units (252).

BACKGROUND

Exposure apparatuses are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an illumination source, a reticle stage assembly that retains a reticle, a lens assembly and a wafer stage assembly that retains a semiconductor wafer. Typically, the wafer stage assembly includes a wafer stage base, a wafer stage that retains the wafer, and a wafer stage mover assembly that precisely positions the wafer stage and the wafer. Somewhat similarly, the reticle stage assembly includes a reticle stage base, a reticle stage that retains the reticle, and a reticle stage mover assembly that precisely positions the reticle stage and the reticle. The size of the images and the features within the images transferred onto the wafer from the reticle are extremely small. Accordingly, the precise relative positioning of the wafer and the reticle is critical to the manufacturing of high density, semiconductor wafers.

Unfortunately, the stage mover assemblies generate heat that can influence the other components of the exposure apparatus. Conventionally, the stage mover assemblies are cooled by forcing a coolant around the movers of the stage mover assembly. However, existing coolant systems do not adequately or efficiently cool the movers of the stage mover assembly. This can reduce the accuracy of positioning of the wafer relative to the reticle, and degrade the accuracy of the exposure apparatus.

SUMMARY

The present invention is directed to a stage assembly that moves a device. In one embodiment, the stage assembly includes (i) a stage that retains the device; (ii) a reaction assembly that is spaced apart from the stage; (iii) a stage mover that moves the stage, the stage mover including a magnet array that is coupled to the stage and a conductor array that is coupled to the reaction assembly, the conductor array including a set of first zone conductor units, and a set of second zone conductor units; (iv) a temperature adjuster that independently adjusts the temperature of the set of first zone conductor units, and the set of second zone conductor units; and (v) a control system that selectively controls the temperature adjuster.

With this design, more circulation fluid can be directed to the conductor units that are used the most and that are generating the most heat. This will allow for the efficient cooling of the stage mover. Further, with this design, the temperature adjuster can efficiently and accurately maintain a substantially uniform temperature of the stage mover and the reaction assembly. This allows for more accurate positioning of the stage.

In one embodiment, the temperature adjuster directs a circulation fluid into the set of first zone conductor units at a first flow rate, and directs the circulation fluid into the set of second zone conductor units at a second flow rate that is different than the first flow rate. In this embodiment, the control system selectively controls the first flow rate to cool the first zone conductor units to a desired first temperature, and selectively adjusts the second flow rate to cool the second zone conductor units to a desired second temperature. Further, in this embodiment, the circulation fluid can be directed to each of the first zone conductor units substantially in parallel, and the circulation fluid can be directed to each of the second zone conductor units substantially in parallel.

Additionally, the conductor array can include a set of third zone conductor units. In this embodiment, the temperature adjuster directs the circulation fluid into the set of third zone conductor units at a third flow rate that is different from the first flow rate and the second flow rate. Further, the control system can selectively control the third flow rate to cool the set of third zone conductor units to a desired third temperature.

In one embodiment, the control system includes a model temperature estimator that estimates the temperature of the first zone conductor units and that estimates the temperature of the second zone conductor units. Further, in this embodiment, the control system adjusts the first flow rate based on the estimated temperature of the first zone conductor units, and adjusts the second flow rate based on the estimated temperature of the second zone conductor units. Moreover, in this embodiment, the stage assembly can include a feedback assembly that provides feedback regarding the temperature of at least a portion of the first zone conductor units and at least a portion of the second zone conductor units. In this embodiment, the feedback can be fed into the model temperature estimator to improve the model temperature estimator.

As provided herein, each of the conductor units can include a surface housing that is adjacent to the magnet array. In this embodiment, the temperature adjuster can direct a surface circulation fluid through the surface housing of each of the conductor units to maintain the temperature of the surface housings at a predetermined surface temperature.

Additionally, each conductor unit can includes a first coil set, a second coil set and a body housing positioned near coil sets. In this embodiment, the circulation fluid is directed through the body housing of each of the conductor units.

In yet another embodiment, the stage assembly can include: (i) a stage that retains the device; (ii) a rigid stage base; (iii) a countermass reaction assembly that is supported by the stage base and that moves relative to the stage base along the first axis; (iv) a planar, stage mover that moves the stage, the stage mover including a magnet array that is coupled to the stage and a conductor array that is coupled to the reaction assembly, the conductor array including a set of first zone conductor units, and a set of second zone conductor units, wherein current directed to the conductor array generates a force that can move the magnet array and the stage along the first axis in a first direction, and the conductor array and the countermass reaction assembly along the first axis in a second direction that is opposite the first direction; wherein each conductor unit includes a first coil set, a second coil set, a body housing positioned near coil sets, and a surface housing; (v) a temperature adjuster that directs (a) a body circulation fluid into the body housing of each of the first zone conductor units at a first flow rate, and into the body housing of each of the second zone conductor units at a second flow rate that is different than the first flow rate; and (b) a surface circulation fluid through the surface housing of each of the conductor units to maintain the temperature of the surface housings at a predetermined surface temperature; and (vi) a control system that selectively controls the temperature adjuster to selectively adjust the first flow rate to cool the first zone conductor units to a desired first temperature, and to selectively adjust the second flow rate to cool the second zone conductor units to a desired second temperature.

The present invention is directed to a method for moving a device that includes the steps of: (i) retaining the device with a stage; (ii) positioning a reaction assembly near the stage; (iii) moving the stage with a stage mover that includes a magnet array that is coupled to the stage and a conductor array that is coupled to the reaction assembly, the conductor array including a set of first zone conductor units, and a set of second zone conductor units; (iv) independently adjusting the temperature of the set of first zone conductor units, and the set of second zone conductor units with a temperature adjuster; and (v) controlling the temperature adjuster with a control system.

The present invention is also directed to an exposure apparatus, a device manufactured with the exposure apparatus, and/or a wafer on which an image has been formed by the exposure apparatus. Further, the present invention is also directed to a method for making an exposure apparatus, a method for making a device and a method for manufacturing a wafer.

DESCRIPTION

Referring initially toFIG. 1, a stage assembly10having features of the present invention includes a stage base12, a stage14, a stage mover16, a reaction assembly18, a temperature adjuster20, and a control system22. The design of each of these components can be varied to suit the design requirements of the assembly10. The stage assembly10can be positioned above a mounting base624(illustrated inFIG. 6). The stage mover16precisely moves the stage14relative to the stage base12and the reaction assembly18.

As an overview, in certain embodiments, the temperature adjuster20can independently control the flow rate of a circulation fluid44to different areas of the stage mover16. With this design, more circulation fluid44can be directed to areas of the stage mover16that are used the most and that are generating the most heat. This will allow for the efficient cooling of the stage mover16. Further, with this design, the temperature adjuster20can efficiently and accurately maintain a substantially uniform temperature of the stage mover16and the reaction assembly18. This allows for more accurate positioning of the stage14.

The stage assembly10is particularly useful for precisely positioning a device26during a manufacturing and/or an inspection process. The type of device26positioned and moved by the stage assembly10can be varied. For example, the device26can be a semiconductor wafer, and the stage assembly10can be used as part of an exposure apparatus630(illustrated inFIG. 6) for precisely positioning the semiconductor wafer during manufacturing of the semiconductor wafer. Alternately, for example, the stage assembly10can be used to move other types of devices during manufacturing and/or inspection, to move a device under an electron microscope (not shown), or to move a device during a precision measurement operation (not shown).

Some of the Figures provided herein include an orientation system that designates an X axis, a Y axis, and a Z axis. It should be understood that the orientation system is merely for reference and can be varied. For example, the X axis can be switched with the Y axis and/or the stage assembly10can be rotated. Moreover, these axes can alternatively be referred to as a first, second, or third axis.

The stage base12supports a portion of the stage assembly10above the mounting base624. In the embodiment illustrated herein, the stage base12is rigid and generally rectangular shaped.

The stage14retains the device26. Further, the stage14is precisely moved by the stage mover16to precisely position the device26. In the embodiments illustrated herein, the stage14is generally rectangular shaped and includes a device holder (not shown) for retaining the device26. The device holder can be a vacuum chuck, an electrostatic chuck, or some other type of clamp.

The stage14can be maintained spaced apart (e.g. above) the reaction assembly18with the stage mover16if the stage mover16is a six degree of freedom mover that moves stage14relative to the reaction assembly18with six degrees of freedom. In this embodiment, the stage mover16functions as a magnetic type bearing that levitates the stage14. Alternatively, for example, the stage14can be supported relative to the reaction assembly18with a stage bearing (not shown), e.g. a vacuum preload type fluid bearing. For example, the bottom of the stage14can include a plurality of spaced apart fluid outlets (not shown), and a plurality of spaced apart fluid inlets (not shown). In this example, pressurized fluid (not shown) can be released from the fluid outlets towards the reaction assembly18and a vacuum can be pulled in the fluid inlets to create a vacuum preload type, fluid bearing between the stage14and the reaction assembly18. In this embodiment, the stage bearing allows for motion of the stage14relative to the reaction assembly18along the X axis, along the Y axis and about the Z axis.

The stage mover16controls and adjusts the position of the stage14and the device26relative to the reaction assembly18and the stage base12. For example, the stage mover16can be a planar motor that moves and positions of the stage14along the X axis, along the Y axis and about the Z axis (“three degrees of freedom” or “the planar degrees of freedom”). Further, in certain embodiments, the stage mover16can also be controlled to move the stage14along Z axis and about the X and Y axes. With this design, the stage mover16is a six degree of freedom mover. Alternatively, in certain embodiments, the stage mover16can be another type of actuator designed to move the stage14with less than six degrees of freedom.

In the embodiments illustrated herein, the stage mover16includes a conductor array36, and an adjacent magnet array38that interacts with the conductor array36. InFIG. 1, the conductor array36is coupled to the reaction assembly18, and the magnet array38secured to the stage14. As provided herein, the array secured to the stage14can be referred to as the moving component of the stage mover16, and the array secured to the reaction assembly18can be referred to as the reaction component of the stage mover16.

In one embodiment, the conductor array36can include a plurality of conductor units40, and each conductor unit40can include one or more conductors (not shown inFIG. 1). The design and number of conductor units40in the conductor array36can vary according to the performance and movement requirements of the stage mover16.

Further, the magnet array38can include one or more magnets. The design of the magnet array and the number of magnets in each magnet array can be varied to suit the design requirements of the stage mover16. Each magnet can be made of a permanent magnetic material such as NdFeB.

Electrical current (not shown) is supplied to the conductors by the control system22. The electrical current in the conductors interacts with the magnetic field(s) of the one or more magnets in the magnet array38. This causes a force (Lorentz type force) between the conductors and the magnets that can be used to move the stage14relative to the stage base12.

Unfortunately, the electrical current supplied to the conductors also generates heat, due to resistance in the conductors. The heat from the conductors is subsequently transferred to the reaction assembly18. This can cause expansion and distortion of the reaction assembly18. Further, the heat from the conductors can be transferred to the surrounding environment, including the air surrounding the conductors. This can adversely influence a measurement system (not shown inFIG. 1) that measures the position of the stage14and the device26. For example, certain measurement systems utilize one or more interferometers. The heat from the conductor array changes the index of refraction of the surrounding air. This reduces the accuracy of the measurement system and degrades machine positioning accuracy. Moreover, the resistance of the conductors increases as temperature increases. This exacerbates the heating problem and reduces the performance and life of the stage mover16.

In certain embodiments, to reduce the influence of the heat from the conductors, the present invention actively cools the reaction assembly18and the conductor units40with the temperature adjuster20.

The reaction assembly18counteracts, reduces and/or minimizes the influence of the reaction forces from the stage mover16on the position of the stage base12and the mounting base624. This minimizes the distortion of the stage base12and improves the positioning performance of the stage assembly10. Further, for an exposure apparatus630, this allows for more accurate positioning of the semiconductor wafer.

As provided above, the conductor array36of the stage mover16is coupled to the reaction assembly18. With this design, the reaction forces generated by the stage mover16are transferred to the reaction assembly18. As a result thereof, when the stage mover16applies a force to move the stage14, an equal and opposite reaction force is applied to the reaction assembly18.

InFIG. 1, the reaction assembly18is a rectangular shaped countermass that is maintained above the stage base12with a reaction bearing (not shown), e.g. a vacuum preload type fluid bearing. For example, the bottom of reaction assembly18can include a plurality of spaced apart fluid outlets (not shown), and a plurality of spaced apart fluid inlets (not shown). Pressurized fluid (not shown) is released from the fluid outlets towards the stage base12and a vacuum is pulled in the fluid inlets to create a vacuum preload type, fluid bearing between the stage base12and the reaction assembly18. In this embodiment, the reaction bearing allows for motion of the reaction assembly18relative to the stage base12along the X axis, along the Y axis and about the Z axis. Alternately, for example, the reaction bearing can be a magnetic type bearing, or a roller bearing type assembly.

With this design, through the principle of conservation of momentum, (i) movement of the stage14with the stage mover16along the X axis in a first X direction along the X axis, generates an equal but opposite X reaction force that moves the countermass reaction assembly18in a second X direction that is opposite the first X direction along the X axis; (ii) movement of the stage14with the stage mover16along the Y axis in a first Y direction, generates an equal but opposite Y reaction force that moves the countermass reaction assembly18in a second Y direction that is opposite the first Y direction along the Y axis; and (iii) movement of the stage14with the stage mover16about the Z axis in a first theta Z direction, generates an equal but opposite theta Z reaction force (torque) that moves the countermass reaction assembly18in a second theta Z direction that is opposite the first theta Z direction about the Z axis.

The design of the countermass reaction assembly18can be varied to suit the design requirements of the reaction assembly18. In certain embodiments, the ratio of the mass of the countermass reaction assembly18to the mass of the stage14is relatively high. This will minimize the movement of the countermass reaction assembly18and minimize the required travel of the countermass reaction assembly18. A suitable ratio of the mass of the countermass reaction assembly18to the mass of the stage14is between approximately 2:1 and 10:1. A larger mass ratio is better, but is limited by the physical size of the reaction assembly18.

In one embodiment, the countermass reaction assembly18is made from a non-electrically conductive, non-magnetic material, such as low electrical conductivity stainless steel or titanium, or non-electrically conductive plastic or ceramic.

Additionally, a trim mover (not shown) can be used to adjust the position of the reaction assembly18relative to the stage base12. For example, the trim mover can include one or more rotary motors, voice coil motors, linear motors, electromagnetic actuators, or other type of actuators.

The temperature adjuster20reduces the influence of the heat from the conductors of the conductor array36from adversely influencing the other components of the stage assembly10and the assemblies nearby the stage assembly10. In one embodiment, the temperature adjuster20efficiently reduces the amount of heat transferred from the conductors to the surrounding environment.

The design of the temperature adjuster20can vary. In one embodiment, the temperature adjuster20includes (i) a body circulation system42that directs a body circulation fluid44(illustrated as small circles) through the reaction assembly18and through a portion of each of the conductor units40; and (ii) a surface circulation system46that directs a surface circulation fluid48(illustrated as small circles) through another portion of the reaction assembly18and another portion of each of the conductor units40. With this design, in one embodiment, the circulation systems42,46can be used to inhibit the transfer of heat from the conductors of the conductor array36to the surrounding environment.

The type of circulation fluid44,48can be varied. For example, the circulation fluid44,48can be water. In certain embodiments, the circulation fluid44,48can be referred to as a coolant.

As provided herein, during use of the stage assembly10(e.g. during an exposure with the exposure apparatus630), the device26is moved by the stage mover16. Typically, during use of the stage assembly10, more current is directed to the conductors in certain conductor units40than the conductors in other conductor units40. For example, certain conductor units40are primarily used to move the wafer26during the scanning portion of an exposure. These conductor units40will generate more heat and will require more cooling. As provided herein, the body circulation system42and/or the surface circulation system46are uniquely designed to provide more cooling to certain conductor units40and/or groups of conductor units40. The design of the circulation systems42,46are discussed in more detail below.

The measurement system monitors movement of the stage14relative to the stage base12, or to some other reference such as an optical assembly686(illustrated inFIG. 6). With this information, the stage mover16can be controlled to precisely position of the stage14. For example, the measurement system can utilize laser interferometers, encoders, and/or other measuring devices to monitor the position of the stage14.

The control system22is electrically connected to, directs and controls electrical current to the conductors of the stage mover16to precisely position the device26. Further, the control system22is electrically connected to and controls the circulation systems42,46of the temperature adjuster to accurately control the temperature of the reaction assembly18and the conductor units40. The control system22can include one or more processors.

FIG. 2is an exploded perspective view of one conductor unit40, a portion of the reaction assembly18, and a portion of a printed circuit board250positioned between the reaction assembly18and the conductor unit40that electrically connects to the conductor unit40. The other conductor units in the conductor array36(illustrated inFIG. 1) can be similar to the conductor unit40illustrated inFIG. 2. Alternatively, the conductor units40can have a different design than that illustrated inFIG. 2.

In this non-exclusive embodiment, the conductor unit40includes a first (“upper”) coil set252; a second (“lower”) coil set254that is positioned below and is spaced apart from the first coil set252; a body circulation assembly256; and a surface circulation assembly258. Alternatively, the conductor unit40can be designed without some of these components. For example, the conductor unit40can be designed to include a single coil set.

The design of each coil set252,254and the number of conductors in each coil set252,254can be varied to suit the design requirements of the stage mover16(illustrated inFIG. 1). InFIG. 2, for a three phase planar motor, each coil set252,254includes three adjacent racetrack shaped coils that are aligned side by side. In one embodiment, (i) the first coil set252can also be referred to as a Y coil set because current directed to the first coil set252is used to generate a force along the Y axis; and (ii) the second coil set254can also be referred to as a X coil set because current directed to the second coil set254is used to generate a force along the X axis. Alternatively, the orientation of the coil sets252,254can switched or the size of the coil sets252,254can be different than that illustrated inFIG. 2.

Each coil can be made of metal such as copper or any substance or material responsive to electrical current and capable of creating a magnetic field such as superconductors. Alternatively, each coil set252,254can include more than three or fewer than three coils.

As provided herein, in one embodiment, (i) the body circulation system42(illustrated inFIG. 1) directs the body circulation fluid44(illustrated inFIG. 1) through the body circulation assembly256of each conductor unit40to remove the heat generated by the operation of the respective conductor unit40; and (ii) the surface circulation system46(illustrated inFIG. 1) directs the surface circulation fluid48(illustrated inFIG. 1) through the surface circulation assembly258of each conductor unit40to maintain an upper, outer surface260of each conductor unit40at the desired temperature. The design of each circulation assembly256,258can be varied to suit the design requirements of each conductor unit40.

InFIG. 2, the body circulation assembly256includes (i) an upper body housing262A that defines one or more upper passageways262B, e.g. micro-channels, (a portion illustrated in phantom) that weave back and forth within the upper body housing262A; (ii) a middle body housing264A that defines one or more middle passageways264B, e.g. micro-channels, (a portion illustrated in phantom) that weave back and forth within the middle body housing264A; and (iii) a lower body housing266A that defines one or more lower passageways266B, e.g. micro-channels, (a portion illustrated in phantom) that weave back and forth within the lower body housing266A. Further, the surface circulation assembly258includes a surface housing268A that defines one or more surface passageways268B, e.g. micro-channels, (a portion illustrated in phantom) that weave back and forth within the surface housing268A. In one embodiment, each housing262A,264A,266A,268A is generally flat, rectangular plate shaped and is made from a non-electrically conductive, non-magnetic material, such as titanium, or non-electrically conductive plastic or ceramic. Further, in this embodiment, the housings262A,264A,266A,268A are substantially parallel to each other.

Moving from the bottom to the top inFIG. 2, the components of the conductor unit40are assembled as follows, (i) the lower body housing266A is positioned adjacent to and above the printed circuit board250; (ii) the lower coil set254is positioned above the lower body housing266A, (iii) the middle body housing264A is positioned adjacent to and above the lower coil set254; (iv) the upper coil set252is positioned adjacent to and above the middle body housing264A; (v) the upper body housing262A is positioned adjacent to and above the upper coil set252; and (vi) the surface housing268A is positioned adjacent to and above the upper body housing262A.

With this design, the body circulation fluid44can be directed through (i) the lower body housing266A, (ii) the middle body housing264A, and (iii) the upper body housing262A to remove the bulk of the heat generated by the coil sets252,254. Further, the surface circulation fluid48can be directed through the surface housing268A to maintain the surface temperature of each conductor unit40at the desired temperature to inhibit the transfer of heat from each conductor unit40.

FIG. 3Ais a simplified top view of the conductor array36including the plurality of conductor units40, and the reaction assembly18, and a schematic of the temperature adjuster20, and the control system22ofFIG. 1. As provided herein, the number and design of conductor units40can be varied according to the movement requirements of the stage assembly10(illustrated inFIG. 1). For example, inFIG. 3A, the conductor array36includes one hundred and eight separate, spaced apart, generally rectangular shaped, conductor units40that are secured to the countermass reaction assembly18in a two dimensional, planar array. It should be noted that the twelve rows and nine columns of the conductor array36are labeled in some of the Figures for reference. Alternatively, the conductor array36can include more than or fewer than one hundred and eight separate conductor units40. Further, one or more of the conductor units40can have a shape other than rectangular.

As provided herein, depending upon the desired usage of the stage assembly10, certain conductor units40will be used more than other conductor units40to move the stage14. Further, the conductor units40that are used more will generate more heat and will require more cooling via the temperature controller20. In one embodiment, the conductor array36and the countermass reaction assembly18are divided into a plurality of different zones depending upon the projected heat generated each conductor unit40and their respective cooling requirements. In one, non-exclusive example, the conductor array36and the countermass reaction assembly18can be divided into (i) a centrally located, rectangular shaped first zone380(the outer boundary illustrated with a short dashed line); (ii) a rectangular tube shaped second zone382(the outer boundary is illustrated with a long dashed line and the inner boundary is illustrated with the short dashed line); (iii) a rectangular tube shaped third zone384(the outer boundary is illustrates with a dash-dot line and the inner boundary is illustrated with the long dashed line); and (iv) a pair of rectangular shaped fourth zones386. Further, in this example, (i) the conductor units40that are part of the first zone380are labeled with an “A” and can be referred to as first zone conductor units340A; (ii) the conductor units40that are part of the second zone382are labeled with a “B” and can be referred to as second zone conductor units340B; (iii) the conductor units40that are part of the third zone384are labeled with a “C” and can be referred to as third zone conductor units340C; and (iv) the conductor units40that are part of the fourth zones386are labeled with a “D” and can be referred to as fourth zone conductor units340D.

In this example, generally speaking, (i) the first zone conductor units340A are used the most and require the most cooling; (ii) the second zone conductor units340B are used the second most and require the second most cooling; (iii) the third zone conductor units340C are used the third most and require the third most cooling; and (iv) the fourth zone conductor units340D are used the least and require the least cooling. In this embodiment, the conductor units40are grouped based on usage. Stated in another fashion, in the embodiment illustrated inFIG. 3A, the conductor array36has been divided (i) a set of first zone conductor units340A that includes twenty conductor units that require approximately the same amount of cooling; (ii) a set of second zone conductor units340B that includes twenty-two conductor units that require approximately the same amount of cooling; (iii) a set of third zone conductor units340C that includes thirty conductor units that require approximately the same amount of cooling; and (iv) two sets of fourth zone conductor units340D that each includes eighteen conductor units that require approximately the same amount of cooling.

Alternatively, depending upon the usage of the stage assembly10, the conductor units40can be grouped into different zones and/or the conductor array36and the countermass reaction assembly18can be divided into more than four or fewer than four zones, and/or the shapes of the zones can be different.

Additionally, the conductor array36can include one or more feedback elements388(represented with an “x”) that provided feedback to the control system22for controlling the temperature adjuster20. In certain embodiments, each of zones380,382,384,386includes one or more feedback elements388. A non-exclusive example of a suitable feedback element388is a temperature sensor.

FIG. 3Bis a simplified top view of the reaction assembly18, and a schematic of the temperature adjuster20, and the control system22. In this embodiment, the reaction assembly18includes (i) a first passageway390that is routed through the first zone380; (ii) a second passageway392that is routed through the second zone382; (iii) a third passageway394that is routed through the third zone384; and (iv) a fourth passageway396that is routed through the fourth zones386. It should be noted that the design of each passageway390,392,394,396can be varied to suit the cooling requirements of the reaction assembly18and the sets of conductor units40. It should also be noted that the simplified illustration of each passageway390,392,394,396is merely for reference.

As one non-exclusive example, (i) the first passageway390can include a manifold (not shown) that is in fluid communication with each of the first zone conductor units340A (illustrated inFIG. 3A); (ii) the second passageway392can include a manifold (not shown) that is in fluid communication with each of the second zone conductor units340B (illustrated inFIG. 3A); (iii) the third passageway394can include a manifold (not shown) that is in fluid communication with each of the third zone conductor units340C (illustrated inFIG. 3A); and (iv) the fourth passageway396can include a manifold (not shown) that is in fluid communication with each of the fourth zone conductor units340D (illustrated inFIG. 3A).

Referring toFIGS. 3A and 3B, the temperature adjuster20independently adjusts and controls the temperature of each of the zones, e.g. the first zone380, the second zone382, the third zone384, and the fourth zone386. The temperature of each zone can be controlled to be the same or different. As provided herein, the body circulation system42can independently direct and control the flow rate of the body circulation fluid44through (i) the first passageway390and the first zone conductor units340A; (ii) the second passageway392and the second zone conductor units340B; (iii) the third passageway394and the third zone conductor units340C; and (iv) the fourth passageway396and the fourth zone conductor units340D.

Stated in another fashion, the temperature adjuster20can direct the body circulation fluid44(i) at a first flow rate through the first passageway390and each of the first zone conductor units340A; (ii) at a second flow rate through the second passageway392and each of the second zone conductor units340B; (iii) at a third flow rate through the third passageway394and each of the third zone conductor units340C; and (iv) at a fourth flow rate through the fourth passageway396and each of the fourth zone conductor units340D. Further, each of the flow rate can be controlled to be different. In this example, the first flow rate is the largest, the second flow rate is the next largest, the third flow rate is the subsequently largest, and the fourth flow rate is the smallest. As a non-exclusive examples, the difference between flow rates can vary approximately 10, 20, 40, 50, or 90 percent. With this design, the temperature adjuster20can efficiently direct the body circulation fluid44to the conductor units40that require the most cooling.

In certain embodiments, the body circulation system42further includes a chiller (not shown) for controlling the temperature of the body circulation fluid44that is delivered to the conductor array36. As is well known to those skilled in the art, such a chiller typically includes both heaters and a refrigeration system to allow precise control of the temperature of body circulation fluid44. According to the specific requirements of each embodiment, the chiller can be configured in a way to allow the temperature adjuster20to adjust the temperature of body circulation fluid44supplied to each of the passageways390,392,394, and396.

In one embodiment, the body circulation system42can include a body fluid source (not shown) that provides pressurized body circulation fluid44to the passageways390,392,394,396at the desired temperature, and a valve assembly398that includes (i) a first valve398A that is independently adjusted to control the first flow rate, (ii) a second valve398B that is independently adjusted to control the second flow rate, (iii) a third valve398C that is independently adjusted to control the third flow rate, and (iv) a fourth valve398D that is independently adjusted to control the fourth flow rate. With this design, the flow rate of the body circulation fluid44can be selectively controlled to be different for each of the circulation zones380,382,384,386. In one embodiment, the flow rates in each circulation zone380,382,384,386and temperature of the first circulation fluid44is controlled to remove the heat from the conductor units40.

In some embodiments, the body circulation system42can include two body fluid sources (not shown) that provides pressurized body circulation fluid44at two different temperatures (e.g., hot and cold) to the valve assembly398. The temperature adjuster20can direct valves (not shown) within valve assembly398to direct varying amounts of body circulation fluid44from each supplied temperature to control the temperature of the body circulation fluid44supplied to each of the passageways390,392,394,396.

For example, each valve398A,398B,398C,398D can be an electronic valve controlled by the control system22. With this design, the control system22can independently and selectively adjust the valves398A,398B,398C,398D to selectively adjust and control the respective flow rate based on the amount of anticipated heat generated in the respective zone380,382,384,386. In this embodiment, the valve assembly398is illustrated outside of the reaction assembly18. Alternatively, the valve assembly398can be positioned within the reaction assembly18.

As a non-exclusive example, the body fluid source can include (i) a reservoir that retains the first circulation fluid44, (ii) a fluid pump that controls the overall flow rate and pressure, and (iii) a chiller/heat exchanger that adjusts the temperature of the first circulation fluid44. Alternatively, the body fluid source can include multiple fluid pumps and multiple reservoirs. Moreover, the first circulation fluid44that is directed through the reaction assembly18can be returned to the reservoir for a closed loop circulation system.

Additionally, the temperature adjuster20can include the surface circulation system46that directs the surface circulation fluid48into the surface housing268A (illustrated inFIG. 2) to maintain the outer surface260of each conductor units40at the predetermined temperature, e.g. the temperature of the room that houses the stage assembly10. With this design, the surface circulation system46can control the flow rate to maintain the desired temperature of the outer surface260of the conductor units40. For example, the desired temperature can be the temperature of the room that houses the stage assembly10. By controlling the temperature of the outer surface260, the amount of heat transferred from the conductor units40to the surrounding environment can be controlled and minimized.

In one embodiment, the surface circulation system46can include a fluid source that provides pressurized surface circulation fluid48to the surface housing268A at the desired temperature and flow rate. For example, the fluid source can include (i) a reservoir that retains the second circulation fluid48, (ii) a fluid pump that controls the overall flow rate and pressure, and (iii) a chiller/heat exchanger that adjusts the temperature of the second circulation fluid48. Moreover, the second circulation fluid48that is directed through the reaction assembly18and the top covers266can be returned to the reservoir for a closed loop circulation system.

The control system22selectively controls the temperature adjuster20. For example, the control system22can selectively control the valves390,392,394,396to selectively and independently control (i) the first flow rate to cool the first zone380to a desired first temperature, (ii) the second flow rate to cool the second zone382to a desired second temperature, (iii) the third flow rate to cool the third zone384to a desired third temperature, and (iv) the fourth flow rate to cool the fourth zone386to a desired fourth temperature. Stated in another fashion, in one embodiment, the temperature controller20is controlled by the control system22to individually and independently adjust the temperature of the different zones380,382,384,386.

As provided herein, the problem of a non-uniform surface temperature of the conductor array36and the countermass reaction assembly18is solved by dividing the conductor array36and the countermass reaction assembly18into a number of separate zones380,382,384,386, and directing the body circulation fluid44into the separate zones380,382,384,386at selectively different rates. This provides an efficient way to maintain a uniform surface temperature of the conductor array36and control the surface temperature of the conductor array36. Further, only a limited number of temperature sensors388are necessary to provide feedback to the control system22.

FIG. 3Cis a simplified schematic of (i) the body circulation system42, (ii) the valves398A,398B,398C,398D, (iii) the set of first zone conductor units340A and the first zone380; (iv) the set of second zone conductor units340B and the second zone382, (v) the set of third zone conductor units340C and the third zone384, (vi) the set of fourth zone conductor units340D and the fourth zone386, and (vii) the control system22. In this embodiment, the control system22dynamically controls the valves398A,398B,398C,398D to control the respective flow rates of the body circulation fluid44to the zones380,382,384,386.

It should be noted that in the embodiment illustrated inFIG. 3C, (i) the body circulation fluid44flows in parallel through the first zone conductor units340A; (ii) the body circulation fluid44flows in parallel through the second zone conductor units340B; (iii) the body circulation fluid44flows in parallel through the third zone conductor units340C; and (iv) the body circulation fluid44flows in parallel through the fourth zone conductor units340D.

FIG. 3Dis a simplified schematic of (i) the surface circulation system46, (ii) the set of first zone conductor units340A and the first zone380; (iii) the set of second zone conductor units340B and the second zone382, (iv) the set of third zone conductor units340C and the third zone384, (v) the set of fourth zone conductor units340D and the fourth zone386, and (vi) the control system22. In this embodiment, the control system22can dynamically control a valve398E to control the flow rate of the surface circulation fluid48to the zones380,382,384,386.

It should be noted that in the embodiment illustrated inFIG. 3D, the surface circulation fluid48flows in parallel through the first zone conductor units340A, the second zone conductor units340B, the third zone conductor units340C, and the fourth zone conductor units340D.

FIG. 4is a simplified top view of another embodiment of the conductor array436including the plurality of conductor units440, and the reaction assembly418, and a schematic of the temperature adjuster20, and the control system22ofFIG. 1. In this embodiment, the conductor array436is similar to the conductor array36described above and illustrated inFIG. 3A. However, in this embodiment, the required movement of the stage (not shown inFIG. 1) is slightly different. Accordingly, the conductor units440are grouped differently and cooled differently than the embodiment illustrated inFIG. 3A.

More specifically, in the non-exclusive example illustrated inFIG. 4, the conductor array436and the countermass reaction assembly418are divided into (i) a centrally located, diagonally shaped first zone480(the outer boundary illustrated with a short dashed line); (ii) a second zone482(the outer boundary is illustrated with a long dashed line and the inner boundary is illustrated with the short dashed line); (iii) a third zone484(the outer boundary is illustrates with a dash-dot line and the inner boundary is illustrated with the long dashed line); and (iv) a pair of fourth zones486. Further, in this example, (i) the conductor units440that are part of the first zone480are labeled with an “A” and can be referred to as first zone conductor units440A; (ii) the conductor units440that are part of the second zone482are labeled with a “B” and can be referred to as second zone conductor units440B; (iii) the conductor units440that are part of the third zone484are labeled with a “C” and can be referred to as third zone conductor units440C; and (iv) the conductor units440that are part of the fourth zones486are labeled with a “D” and can be referred to as fourth zone conductor units440D.

In this example, generally speaking, (i) the first zone conductor units440A are used the most and require the most cooling; (ii) the second zone conductor units440B are used the second most and require the second most cooling; (iii) the third zone conductor units440C are used the third most and require the third most cooling; and (iv) the fourth zone conductor units440D are used the least and require the least cooling. In this embodiment, the conductor units40are grouped based on usage. Stated in another fashion, in the embodiment illustrated inFIG. 4, the conductor array36has been divided (i) a set of first zone conductor units440A that includes nineteen conductor units that require approximately the same amount of cooling; (ii) a set of second zone conductor units440B that includes twenty-six conductor units that require approximately the same amount of cooling; (iii) a set of third zone conductor units440C that includes thirty conductor units that require approximately the same amount of cooling; and (iv) two sets of fourth zone conductor units440D that each includes sixteen conductor units that require approximately the same amount of cooling.

FIG. 5is a simplified schematic of one embodiment of the control system522. In this embodiment, the present invention utilizes a (computer generated) model temperature estimator504that is a simulated physical model of the conductor array (not shown inFIG. 5) and/or the countermass reaction assembly18(not shown inFIG. 5) that simulates conditions that are substantially similar to the conditions to which the conductor array and/or the countermass reaction assembly itself is subjected. With the present invention, using a mathematical model (model temperature estimator)504of the conductor array, (with the projected movements of the stage) the heat distribution (transient and steady state) can be calculated for each zone (not shown inFIG. 5). By evaluating the heat that is transferred from the conductor array to the countermass reaction assembly, the control system522, via the model temperature estimator can control the temperature controller (not shown inFIG. 5) to accurately control the temperature of the zones.

In the non-exclusive embodiment illustrated inFIG. 5, the control system522includes a control loop for each zone. In the first control loop, the first zone input500A, e.g. the projected usage of the first zone conductor units is fed into the system. Block502A represents the first zone system and block504A represents the model temperature estimator for the first zone. With this design, the model temperature estimator504A estimates the first zone output508A, e.g. the cooling requirements for the first zone. Further, block506A represents feedback gain into the estimator504A to improve the performance of the estimator.

Similarly, in the second control loop, the second zone input500B, e.g. the projected usage of the second zone conductor units is feed into the system. Block502B represents the second zone system and block504B represents the model temperature estimator for the second zone. With this design, the model temperature estimator504B estimates the second zone output508B, e.g. the cooling requirements for the second zone. Further, block506B represents feedback gain into the estimator504B to improve the performance of the estimator.

Further, in the third control loop, the third zone input500C, e.g. the projected usage of the third zone conductor units is feed into the system. Block502C represents the third zone system and block504C represents the model temperature estimator for the third zone. With this design, the model temperature estimator504C estimates the third zone output508C, e.g. the cooling requirements for the third zone. Further, block506C represents feedback gain into the estimator504C to improve the performance of the estimator.

Finally, in the fourth control loop, the fourth zone input500D, e.g. the projected usage of the fourth zone conductor units is fed into the system. Block502D represents the fourth zone system and block504D represents the model temperature estimator for the fourth zone. With this design, the model temperature estimator504D estimates the fourth zone output508D, e.g. the cooling requirements for the fourth zone. Further, block506D represents feedback gain into the estimator504D to improve the performance of the estimator.

With the present invention, utilizing the simulated physical model (mathematical model; model temperature estimator)504, the control system522predicts the required coolant flow for each zones, and controls the temperature controller to selectively and individually control the flow of the circulation fluid to each of the zones to achieve the predicted cooling requirements. For example, the model temperature estimator504can estimate a temperature of each of the zones based on the projected usage of the conductor units. With this design, the temperature adjuster can be controlled to accurately control the temperature of the zones.

Further, with the feedback from the conductor array and/or the countermass reaction assembly (e.g. with the feedback elements), the model temperature estimator504can be regularly updated and improved so as to more accurately and effectively predict the required coolant flow rate for each zone, and control the temperature of the conductor array and/or the countermass reaction assembly. As a result thereof, in certain embodiments, using a limited number of temperature sensors in conjunction with a system thermal model, the flow rate to various zones can be controlled. In certain embodiments, the purpose of the sensors is to update the thermal model, which in turn is used to determine the flow rates for a coil unit or groups of coil unit.

Alternatively, the control system can use the feedback elements to directly determine the required flow rates to each of the zones.

FIG. 6is a schematic view illustrating an exposure apparatus630useful with the present invention. The exposure apparatus630includes the apparatus frame680, an illumination system682(irradiation apparatus), a reticle stage assembly684, an optical assembly686(lens assembly), and a wafer stage assembly610. The stage assemblies provided herein can be used as the wafer stage assembly610. Alternately, with the disclosure provided herein, the stage assemblies provided herein can be modified for use as the reticle stage assembly684.

The exposure apparatus630is particularly useful as a lithographic device that transfers a pattern (not shown) of an integrated circuit from the reticle688onto the semiconductor wafer690. The exposure apparatus630mounts to the mounting base624, e.g., the ground, a base, or floor or some other supporting structure.

The apparatus frame680is rigid and supports the components of the exposure apparatus630. The design of the apparatus frame680can be varied to suit the design requirements for the rest of the exposure apparatus630.

The illumination system682includes an illumination source692and an illumination optical assembly694. The illumination source692emits a beam (irradiation) of light energy. The illumination optical assembly694guides the beam of light energy from the illumination source692to the optical assembly686. The beam illuminates selectively different portions of the reticle688and exposes the semiconductor wafer690. InFIG. 6, the illumination source692is illustrated as being supported above the reticle stage assembly684. Alternatively, the illumination source692can be secured to one of the sides of the apparatus frame680and the energy beam from the illumination source692is directed to above the reticle stage assembly684with the illumination optical assembly694.

The optical assembly686projects and/or focuses the light passing through the reticle to the wafer. Depending upon the design of the exposure apparatus630, the optical assembly686can magnify or reduce the image illuminated on the reticle.

The reticle stage assembly684holds and positions the reticle688relative to the optical assembly686and the wafer690. Similarly, the wafer stage assembly610holds and positions the wafer690with respect to the projected image of the illuminated portions of the reticle688.

There are a number of different types of lithographic devices. For example, the exposure apparatus630can be used as scanning type photolithography system that exposes the pattern from the reticle688onto the wafer690with the reticle688and the wafer690moving synchronously. Alternatively, the exposure apparatus630can be a step-and-repeat type photolithography system that exposes the reticle688while the reticle688and the wafer690are stationary.

However, the use of the exposure apparatus630and the stage assemblies provided herein are not limited to a photolithography system for semiconductor manufacturing. The exposure apparatus630, 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 by closely locating a mask and a substrate without the use of a lens assembly. Additionally, the present invention provided herein can be used in other devices, including other semiconductor processing equipment, elevators, machine tools, metal cutting machines, inspection machines and disk drives.

In the embodiments previously described herein and illustrated inFIG. 1, the stage assembly10includes a single stage14that is moved relative to the stage base12. Alternately, for example, as illustrated inFIG. 7, the stage assembly710can be designed to include multiple stages714A,714B (only two are illustrated inFIG. 7) that can be independently moved and positioned relative to the stage base712. As a non-exclusive example, the multiple stages714A,714B can be used in a photolithography system including an exposure region and a measurement region. In this case, each region can be divided into a plurality of different zones similar to the embodiments described above, based on the cooling requirements of the respective conductor units740. Such multiple stages are described in U.S. Pat. No. 6,208,407 and U.S. Pat. No. 6,590,634. As far as permitted, the contents of U.S. Pat. Nos. 6,208,407 and 6,590,634 are incorporated herein by reference. Further, inFIG. 7, (i) the conductor units740are labeled with “A”, “B”, and “C” similar to the coil units40shown inFIG. 3A. (The conductor units740positioned underneath each stage714A,714B are labeled with “A”).

In this embodiment, the temperature adjuster720can independently control the flow rate of the circulation fluid744to different zones. With this design, more circulation fluid744can be directed to conductor units740that are used the most and that are generating the most heat. This will allow for the efficient cooling.

As described above, a photolithography system according to the above described embodiments 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. Needless to say, 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.

FIG. 8is a simplified top view of the conductor array836including the plurality of conductor units840, and the reaction assembly818, and the control system822that are similar to the corresponding components described above. However, in this embodiment, the temperature adjuster820is slightly different. More specifically, in this embodiment, the temperature adjuster820is designed to independently adjust and control both the temperature and the flow rate of the body circulation fluid that is directed to each of the zones, e.g. the first zone880, the second zone882, the third zone884, and the fourth zone886. Alternatively, the temperature adjuster820can be designed to control the temperature of the circulation fluid without adjusting the rate to each zone.

In the Embodiment illustrated inFIG. 8, the temperature adjuster820includes multiple body circulation systems in addition to the surface circulation system846. For example, the temperature adjuster820can include a first body circulation system842A that delivers a first body circulation fluid844A at a first outlet temperature, and a second body circulation system842B that delivers a second body circulation fluid844B at a second outlet temperature that is different from the first outlet temperature (e.g one hot and one cold) to the valve assembly898. In this embodiment, the control system822can independently control the valves898A,898B,898C,898D within valve assembly898to direct varying amounts of each body circulation fluid844A,844B from each supplied temperature to independently control the temperature of the body circulation fluid supplied to each of the zones880,882,884,886.

With this design, the temperature adjuster820can direct the body circulation fluid (i) at a first flow rate and at a first temperature through the zone880; (ii) at a second flow rate and at a second temperature through the second zone882; (iii) at a third flow rate and at a third temperature through the third zone884; and (iv) at a fourth flow rate and at a fourth temperature through the fourth zone886. It should be noted that the flow rates can be the same or different for each zone880,882,884,886, and/or the temperatures can be the same or different for each of the zone880,882,884,886.

FIG. 9is a perspective view of a portion of another embodiment of a stage mover916, a reaction assembly918, and a temperature adjuster920. In this embodiment the stage mover916is a linear motor that includes (i) a moving magnet array (not shown inFIG. 9) that is attached to the stage (not shown inFIG. 9); and (ii) a pair of spaced apart conductor arrays936A,936B that are secured to the reaction assembly918. In this embodiment, each conductor arrays936A,936B includes a plurality of conductor units940. Further the conductor units940can be divided into a number of different sets or zone depending upon the projected usage. In this embodiment, the temperature adjuster920can independently adjust the temperature and/or flow rate of the circulation fluid944to each of the zones similar to the method described above.

Semiconductor devices can be fabricated using the above described systems, by the process shown generally inFIG. 10A. In step1001the device's function and performance characteristics are designed. Next, in step1002, a mask (reticle) having a pattern is designed according to the previous designing step, and in a parallel step1003a wafer is made from a silicon material. The mask pattern designed in step1002is exposed onto the wafer from step1003in step1004by a photolithography system described hereinabove in accordance with the present invention. In step1005the semiconductor device is assembled (including the dicing process, bonding process and packaging process), finally, the device is then inspected in step1006.

FIG. 10Billustrates a detailed flowchart example of the above-mentioned step1004in the case of fabricating semiconductor devices. InFIG. 10Bin step1011(oxidation step), the wafer surface is oxidized. In step1012(CVD step), an insulation film is formed on the wafer surface. In step1013(electrode formation step), electrodes are formed on the wafer by vapor deposition. In step1014(ion implantation step), ions are implanted in the wafer. The above mentioned steps1011-1014form the preprocessing steps for wafers during wafer processing, and selection is made at each step according to processing requirements.

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 step1015(photoresist formation step), photoresist is applied to a wafer. Next, in step1016(exposure step), the above-mentioned exposure device is used to transfer the circuit pattern of a mask (reticle) to a wafer. Then in step1017(developing step), the exposed wafer is developed, and in step1018(etching step), parts other than residual photoresist (exposed material surface) are removed by etching. In step1019(photoresist removal step), unnecessary photoresist remaining after etching is removed.

Multiple circuit patterns are formed by repetition of these preprocessing and post-processing steps.