Table device and charged particle beam device provided with same

Abstract

The present invention provides a stage device and a charged particle beam device provided with the stage device, which can prevent thermal deformation of a stage and improve positional accuracy of stage positioning even in a manner of arranging a Peltier module on a stage on a fixed side. A table device is provided with: a linearly moving first table; a first fin extending in the direction of linear movement of the first table and having a comb-shaped cross-sectional shape; a second table having a second fin disposed facing the first fin and fixed when viewed from the first table; and a heat transfer mechanism that performs heat transfer while maintaining a non-contact relationship between the first fin and the second fin, a Peltier module is provided between the second fin and the second table, one heat transfer surface of the Peltier module is in contact with the second fin, and the other heat transfer surface of the Peltier module is in contact with the second table. The stage device has a control unit for controlling the temperature of the second fin by means of the Peltier module, and the charged particle beam device is provided with the stage device.

Description

Technical Field

[0001] The present invention relates to a worktable apparatus and a charged particle beam apparatus having the worktable apparatus. Background Technology

[0002] The integration level of semiconductor products is increasing year by year, and their circuit patterns are becoming increasingly sophisticated. Various inspection methods are used for semiconductor wafers with circuit patterns to improve quality management and yield. One such method is the technique of using a scanning electron microscope to photograph semiconductor wafers and inspecting the circuit patterns based on the obtained images.

[0003] In samples such as semiconductor wafers, circuit patterns are formed at high density, thus requiring particularly high positional accuracy in the stage setup of scanning electron microscopes.

[0004] One method for improving the positional accuracy of a stage assembly is to use a floating stage to prevent vibration propagation and positional errors caused by vibration. However, since the stage assembly for a scanning microscope is used in a vacuum space, heat dissipation of the stage becomes difficult when it is formed as a floating stage. If heat dissipation of the stage is not possible, the stage temperature changes due to the heat generated inside the stage, and the positional accuracy deteriorates due to the resulting thermal deformation. Therefore, Patent Document 1 discloses a technique for improving positional accuracy by actively cooling the floating stage. Patent Document 1 discloses the following technique: In order to further improve positional accuracy by preventing thermal deformation by suppressing the temperature rise of the stage, a blackbody surface is made on the magnetically floating stage in a vacuum, a radiation plate is placed in a non-contact state relative to the blackbody surface, and the radiation plate is cooled from the back using a Peltier element, and the opposite side of the Peltier element is cooled with a cooling plate, thereby suppressing thermal deformation of the stage. In addition, Patent Document 1, as another embodiment, shows that the Peltier element is arranged on the upper side of the magnetic levitation stage, and is divided and arranged on the plane. The Peltier element is driven according to the planar position of the stage to achieve effective cooling.

[0005] On the other hand, compared with the heat conduction of solids, the heat transfer capacity of radiation heat transfer (=radiative heat transfer) is generally weaker. Under the same temperature difference, the heat flux of radiation heat transfer tends to be smaller than that of the heat conduction of solids. As one means to solve this problem, there is Patent Document 2. In Patent Document 2, in order to increase the area of ​​the surface for radiation heat transfer, comb-shaped fins are arranged facing each other, and radiation heat transfer occurs between the two fins, thereby increasing the heat transfer area per unit space. Furthermore, the fins extend in the direction of table movement, so that even if the table moves, the fins will not interfere with each other. In addition, Patent Document 2 shows a Peltier element arranged on the side of the table that moves relative to the fixed side. When the Peltier element is arranged on the fixed side of the moving table, the relative positional relationship between the Peltier element and the moving table always changes, but when the Peltier element is arranged on the moving table side, the relative positional relationship is fixed and maintained. This means that no matter how the table moves back and forth, the relative position of the Peltier element will not change, thus becoming a major advantage in temperature control of the table.

[0006] As in Patent Document 2, when the Peltier element is positioned on the moving worktable side, the heat required for the Peltier element to operate also needs to be transferred to the fixed side via radiative heat transfer. On the other hand, when the Peltier element is positioned on the fixed side as in Patent Document 1, there is no need for radiative heat transfer to generate the heat required for the Peltier element to consume electricity. Therefore, the method of positioning the Peltier element on the moving worktable side has the disadvantage of a larger radiative heat transfer load compared to the method of positioning the Peltier element on the fixed side.

[0007] Furthermore, when the Peltier element is arranged on the fixed side as in Patent Document 1, and the comb-shaped fins are used facing each other as in Patent Document 2, the time delay caused by the temperature change of the fins makes it difficult to properly control the temperature of the worktable.

[0008] In typical devices, the time it takes for a worktable to remain stationary until it moves to the next location is not long. When a Peltier element is positioned on the fixed side, the control system needs to respond when the worktable moves, ensuring the Peltier element at the new destination cools the worktable. However, when the Peltier element cools the fins by increasing radiative heat transfer through the temperature difference between opposing fins, the heat capacity of the fins is delayed until the temperature of the cooled fins drops after the Peltier element absorbs heat. Therefore, even if the goal is to cool the worktable by increasing heat absorption and lowering the fin temperature after the worktable moves, the worktable may move to the next location before the fin temperature drops sufficiently, resulting in inadequate cooling. In the case of a Peltier element positioned on the moving side of the worktable, as in Patent Document 2, the Peltier element follows the movement of the worktable, thus eliminating this problem. However, this structure presents the problem of a large radiative heat transfer load compared to arranging Peltier elements on the fixed side.

[0009] In the case where the heat-absorbing surface of the Peltier element is used directly as the radiative heat transfer surface without using fins, as in Patent Document 1, the heat absorbed from the worktable changes immediately when the current of the Peltier element changes, so the aforementioned delay is not a problem. However, when the Peltier element is arranged on a fixed side and comb-shaped fins are used, the time delay of the temperature control system is large compared to the time interval of the worktable moving in the space, thus presenting a unique problem of difficulty in controlling the temperature of the worktable.

[0010] Patent Document 1: Japanese Patent Application Publication No. 2003-058258

[0011] Patent Document 2: Japanese Patent Application Publication No. 2006-351741 Summary of the Invention

[0012] The purpose of this invention is to provide a worktable device and a charged particle beam device having the worktable device. The worktable device can reduce the load on cooling the worktable through radiative heat transfer, thereby achieving high efficiency, and prevent thermal deformation by preventing changes in the worktable temperature over time, thereby improving the positional accuracy of the worktable during positioning.

[0013] The structure of the present invention for achieving the above objectives is as follows.

[0014] A worktable device includes: a first worktable that moves linearly; a first fin extending in the direction of linear movement of the first worktable and having a comb-like cross-sectional shape; a second worktable having a second fin arranged opposite to the first fin and fixed when viewed from the first worktable; and a heat transfer mechanism that transfers heat while maintaining a non-contact relationship between the first and second fins. A Peltier module is provided between the second fin and the second worktable, one heat transfer surface of the Peltier module contacting the second fin and the other heat transfer surface contacting the second worktable. The worktable device has a control unit that controls the temperature of the second fin via the Peltier module, thereby controlling the heat transfer between the second fin and the first fin on the first worktable side. Furthermore, a plurality of Peltier modules disposed on the second worktable are arranged in the direction of movement of the first worktable. By controlling these plurality of Peltier modules, the temperature of the second fin is homogenized, thereby achieving uniform heat transfer regardless of the location of the first worktable. Additionally, a charged particle beam device comprising this worktable device is also included.

[0015] By arranging Peltier elements on the fixed-side worktable, the load of radiative heat transfer can be reduced, and the heat transfer capacity can be improved by increasing the surface area through fins. Furthermore, a worktable device and a charged particle beam device equipped with the worktable device can be provided. This worktable device can solve the problem of temperature control delay caused by the heat capacity of the fins, thereby preventing the worktable temperature from changing over time, thus preventing thermal deformation of the worktable, and improving the positional accuracy of the worktable during positioning. Attached Figure Description

[0016] Figure 1 The diagram shows the worktable device of Embodiment 1 viewed from the direction opposite to the movement of the floating worktable.

[0017] Figure 2 This is a diagram of the worktable device in Embodiment 1, viewed from the perspective of observing the movement of the floating worktable laterally.

[0018] Figure 3 This is a diagram of the workbench device and system in Embodiment 2.

[0019] Figure 4 This is a diagram of the workbench device and system in Embodiment 3.

[0020] Figure 5 This is a diagram of the workbench device and system in Embodiment 4.

[0021] Figure 6 This is a diagram of the workbench device and system in Embodiment 5.

[0022] Figure 7 This is a diagram of the workbench device and system in Embodiment 6.

[0023] Figure 8 This is a diagram of the workbench device and system in Embodiment 7. Detailed Implementation

[0024] Hereinafter, embodiments of the present invention will be described using the accompanying drawings.

[0025] [Example 1]

[0026] Figure 1 and Figure 2 This illustrates the structure and system of the workbench device in Embodiment 1 of the present invention. Figure 1 and Figure 2 The diagram shows the observation stage device with its orientation changed by 90°, representing the same device.

[0027] In this worktable device, the upper worktable 1 is a floating worktable, and the lower worktable 2 is a guide rail type worktable. Figure 1 In this process, the upper worktable 1 (also called the "floating worktable" or "first worktable") moves in the depth direction of the paper, indicated by arrow 100. Additionally, the lower worktable 2 (also called the "second worktable") moves in the direction of arrow 101. Figure 2 In the middle, the upper worktable 1 moves in the direction indicated by arrow 100, and the lower worktable 2 moves in the direction of paper depth.

[0028] The upper worktable 1 is driven by a linear motor, which consists of a coil component 46 as the mover and a magnet component 47 as the stator. Current flows through the coil component 46 in the magnetic field formed by the magnet component 47, thereby generating thrust. This thrust is transmitted to the upper worktable 1, causing it to move in the direction of arrow 100. When this worktable is driven, heat is generated due to the current flowing through the coil component. That is, the coil must have resistance, and Joule heating is generated proportional to the product of the resistance and the square of the current flowing through it. Since the coil component 46 needs to transmit thrust to the upper worktable 1, the two are necessarily connected, and the Joule heat from the coil component 46 is transferred to the upper worktable 1, causing its temperature to rise. Furthermore, in Figure 1 , Figure 2 The diagrams of the mechanism for raising the upper worktable 1, the mechanism for measuring the position of the worktable, and the mechanism for driving the lower worktable 2 are omitted.

[0029] like Figure 1As shown, a heat sink 5 (also referred to as the "first fin") is mounted on the bottom surface of the floating platform 1. The heat sink 5 has a comb-shaped cross-section and extends along the depth direction of the floating platform 1 while maintaining the same cross-sectional shape. The heat absorber fin 6 (also referred to as the "second fin"), described later, also has a comb-shaped cross-sectional shape. The two fins are configured such that the front ends of the comb teeth face each other, with the comb teeth intersecting each other's gaps. With this configuration, it is possible to form a shape in which most of the surface area of ​​the two fins faces each other.

[0030] Thermal radiation generated from the surface of a solid is proportional to the fourth power of its absolute temperature, and it possesses the characteristic of absorbing or reflecting the energy of thermal radiation when subjected to it. The ratio of thermal radiation absorbed by a solid surface is called emissivity, which is the same as the ratio of the heat radiated by a blackbody surface to the actual thermal radiation generated. Therefore, it is preferable that the heat sink 5 and the heat absorber 6 respectively increase the emissivity of the surface. In the heat sink 5, the temperature decreases as heat is released from the surface of the fins, moving from the root of the comb teeth towards the tip. Therefore, regarding the material of the fins, a material with high thermal conductivity is preferred. In addition, in a repeatedly moving worktable, the lighter the mass of the component, the smaller the inertial force, thus reducing vibration. Therefore, the lower the material density (lower specific gravity) of the fins, the better. Aluminum, especially materials such as A6063 and A6061, are suitable for fins as materials with high thermal conductivity and low density. On the other hand, aluminum generally has low emissivity, so when forming fins with aluminum, it is preferable to perform a surface treatment to increase the emissivity. In addition, aluminum materials are typically modified by applying an alumina film to improve their corrosion resistance. Special alumina film treatments that enhance emissivity can be applied to both heat sinks and heat absorbers.

[0031] The heat absorber 6 is connected to the lower worktable 2 via (through) a Peltier module 7. Preferably, the heat absorber 6 does not directly contact the lower worktable 2, allowing for more precise temperature control of the heat absorber 6 via the Peltier module 7 (also referred to as the "first Peltier module"). The Peltier module 7 typically consists of multiple Peltier elements arranged on an electrically insulating plate, connected by circuitry. Both the upper and lower surfaces are made of insulating plates, thus making one surface the heat absorber and the other the heat dissipation surface.

[0032] In this embodiment, the upper surface of the Peltier module 7 is a heat-absorbing surface, which cools the heat-absorbing sheet 6. Additionally, the lower surface of the Peltier module 7 is a heat-dissipating surface, which transfers the heat dissipated by the Peltier module 7 to the lower worktable 2 by contacting this surface. The law of conservation of energy also holds true when the Peltier module 7 is activated. Therefore, the total heat absorbed by the Peltier module and the heat consumed (e.g., the power supplied) constitutes the heat dissipation. Therefore, without heat dissipation, heat absorption is impossible. Thus, cooling the heat-absorbing sheet 6 using the Peltier module 7 is primarily achieved by dissipating heat to the lower worktable 2. The lower worktable 2 transfers the heat received from the Peltier module 7 to the guide rail 3 via the sliding unit 8, and this heat is then transferred to the base 4 of the worktable device. In cases where the worktable device is located within a vacuum container, the base 4 is typically a vacuum container.

[0033] To efficiently cool the floating worktable using the heat absorber 6, the heat absorber 6 can absorb only radiative heat from the heat sink 5, without accepting heat transfer from other components. As a means to achieve this, the fins at both ends of the heat absorber 6 can be covered by heat sinks (if...). Figure 1 The structure allows the heat sink 5 to have one more fin than the heat absorber 6 (e.g., one more fin). This prevents the heat absorber 6 from absorbing heat from other components and creating an unnecessary load in the Peltier module 7.

[0034] Furthermore, the back side of the root of the comb-shaped heat absorber 6 faces the lower worktable 2. Ideally, the heat absorber 6 should not receive radiative heat transfer from the lower worktable 2, and the back side of the heat absorber 6 can reduce its emissivity.

[0035] When the heat absorber fin 6 is made of aluminum, only the surface of the fin can be treated to increase its emissivity, while the aluminum substrate is exposed on the back side, resulting in a high reflectivity. Alternatively, in a configuration where the heat absorber fin 6 is fixed together with the Peltier module 7 to the lower worktable 2, a structure that suppresses heat conduction can also be used.

[0036] When the heat absorber 6 is installed by pressing it against the lower worktable 2 with bolts in place of the Peltier module 7, applying pressing pressure to the heat transfer surface is appropriate. However, if the bolt has high thermal conductivity, heat will flow from the lower worktable 2 to the low-temperature heat absorber 6, and the cooling load on the Peltier module will increase accordingly. Therefore, the bolts used to install the heat absorber 6 on the lower worktable with respect to the Peltier module 7 can be made of a material with low thermal conductivity, such as resin.

[0037] To maintain a constant temperature of the floating platform 1 at the target temperature, a temperature measurement unit (not shown) can be used to measure its temperature while simultaneously sending a command to the power supply unit 10 that supplies current to the Peltier module 7, thus providing feedback control over the cooling capacity of the Peltier module 7. The measured temperature of the floating platform 1 is recorded as Ts, and the target temperature is recorded as Ts'. When Ts > Ts', the current flowing through the Peltier module 7 is increased, increasing the cooling capacity. Conversely, when Ts < Ts', the current flowing through the Peltier module 7 is decreased, reducing the cooling capacity. Furthermore, to improve this control action, PID control can be implemented. That is, the current flowing through the Peltier module 7 is determined by using three variables: the value of Ts-Ts', the time derivative of that value, and the time integral of that value, by setting proportional coefficients (i.e., weighting) for each of the three variables and summing the results.

[0038] Alternatively, a control method considering the following delay time can be used: the delay time from the change of current flowing through the Peltier module 7 until the temperature of the heat absorber 6 changes, and then until the temperature of the heat sink 5 and the floating stage body 1 changes. These control calculations are performed by the controller 11 (also called the "control unit" or "controller").

[0039] like Figure 2 As shown, when observing the movement of the floating worktable 1 from a horizontal perspective, in this embodiment, three Peltier modules 7 are arranged in the direction of movement of the floating worktable 1. Here, three are arranged as an example; the number can be changed as needed. To enable the floating worktable 1 to move back and forth, a movement range larger than the size of the main body 1 is set. To ensure cooling capacity at any position within this movement range, multiple Peltier modules can be arranged in the direction of movement of the worktable.

[0040] Thus, when using multiple Peltier modules, in this embodiment, a parallel circuit is used to supply current, applying the same voltage (V) to all Peltier modules. The purpose of applying the same voltage is to homogenize the temperature of the heat-absorbing plate 6 relative to the direction of movement of the floating stage 1. Furthermore, in Figure 2 The diagram illustrates the shape of the heat absorber 6 divided for each Peltier module, but the entire heat absorber 6 can also be manufactured as a single piece.

[0041] When manufactured as a single unit, it has the advantage of uniform temperature throughout through heat conduction from the solid. On the other hand, if the temperature of the heat absorber is significantly reduced, the temperature difference compared to other components becomes larger, and the heat absorber alone undergoes significant thermal contraction, generating thermal stress. This reduction in thermal stress is achieved by dividing the heat absorber 6 into segments for each Peltier module.

[0042] like Figure 2 As shown, when the floating platform 1 remains on the left side of its movement range for an extended period, heat exchange primarily occurs with the heat-absorbing fin 6 on the left. That is, the heat generated by the floating platform 1 is transferred to the heat-absorbing fin 6 via the heat sink 5. However, at this time, radiative heat transfer mainly occurs at the points where the fins face each other, so the heat-absorbing fin 6 only applies a heat load to the area where the heat sink 5 is located. Even so, by measuring the temperature of the floating platform 1 and using feedback control to regulate the cooling capacity of the Peltier module, the floating platform 1 can be brought to the target temperature. However, this is the case when the floating platform 1 remains stationary in the same location; the situation is different if the floating platform 1 is assumed to move back and forth.

[0043] When the floating platform 1 remains stationary on the left side of its deflection range for an extended period, and multiple Peltier modules operate with the same cooling capacity, although the floating platform 1 maintains the target temperature, the heat-absorbing fins 6 in the areas without the floating platform are not subjected to heat load and become subcooled. That is, Figure 2 The heat absorber fin 6 on the right side is at a lower temperature compared to the left side. However, this is acceptable when the floating platform 1 is not on the right side, but when it suddenly moves to the right, the floating platform overcools. If overcooling of the floating platform 1 is detected, the cooling capacity of the Peltier module can be reduced, but this introduces a time delay, thus making a temporary drop in the temperature of the floating platform unavoidable. In contrast, if... Figure 2 This situation can be prevented by using a parallel circuit to supply current to multiple Peltier modules.

[0044] The mathematical formula for the action characteristics of the Peltier module is used to explain the principle that enables the above situation. The variables used in the formula are listed in Table 1.

[0045] [Table 1]

[0046]

[0047] First, Equation (1) represents the heat absorption [W] of the Peltier module.

[0048] [Formula 1]

[0049]

[0050] The heat absorption of the Peltier module is proportional to the current flowing through it, and the proportionality coefficient can be expressed using the Seebeck coefficient and the absolute temperature of the heat-absorbing surface. On the other hand, the temperature difference between the heat dissipation surface and the heat absorption surface of the Peltier module, as represented by equation (3), causes heat conduction, which reduces the heat absorption of the Peltier module.

[0051] [Formula 2]

[0052]

[0053] Furthermore, the resistance of the Peltier module generates Joule heat corresponding to the current flowing through it, with half of this heat flowing to the absorbing surface and half to the dissipating surface. On the other hand, the first term on the right side of equation (2), which relates to the heat dissipation of the Peltier module, represents the effect of the current, and its proportionality coefficient is composed of the Seebeck coefficient and the absolute temperature of the dissipating surface.

[0054] [Formula 3]

[0055] ΔT=T H -T C ...(3)

[0056] Due to the Seebeck effect, the coefficients of heat absorption and heat dissipation relative to the current are different. This Seebeck effect can be described by equation (4), which is the phenomenon of generating a thermoelectric potential proportional to the temperature difference between the heat dissipation surface and the heat absorption surface.

[0057] [Formula 4]

[0058] V Z =αΔT...(4)

[0059] Due to the Seebeck effect, the voltage applied across the Peltier module is described as in equation (5).

[0060] [Formula 5]

[0061] V=IR+α△T...(5)

[0062] That is, the sum of the voltage generated by current × resistance and the thermoelectric potential generated by the Seebeck effect becomes the voltage when current flows through the Peltier module. Incidentally, the power supplied to the Peltier module (=power consumed) is the same as that of a normal DC current load and can be calculated by voltage × current. In addition, the law of conservation of energy, which states that the difference between heat dissipation and heat absorption is the power consumed, holds true through the mathematical formula of this system. If we take the difference between equation (2) and equation (1), we can confirm the relationship of equation (6).

[0063] [Formula 6]

[0064] P = VⅠ = Q H -Q C ...(6)

[0065] As explained by the mathematical formula of this system, in the Peltier module, a thermoelectric electromotive force (i.e., voltage) is generated in proportion to the temperature difference between the heat-dissipating and heat-absorbing surfaces. Figure 2In the illustrated configuration, the floating stage 1 is positioned biased to the left, thus preventing the heat-absorbing fins on the right from being subjected to thermal load, which could cause them to become overcooled. In this case, the temperature of the heat-absorbing surface of the right-side Peltier module is lower than that of the other Peltier modules. This also means that the temperature difference between the heat-dissipating surface and the heat-absorbing surface of the right-side Peltier module is greater. Consequently, the thermoelectric electromotive force generated by the Seebeck effect is greater than that of the other Peltier modules.

[0066] When the same voltage is applied to all Peltier modules, if the thermoelectric potential of one Peltier module increases, the voltage across the current multiplied by the resistance decreases accordingly. This voltage decrease means that the current flowing through the Peltier module decreases. Therefore, when the same voltage is applied to multiple Peltier modules, if there is a Peltier module whose absorber surface temperature decreases and thus its thermoelectric potential increases, the current flowing in that Peltier module is lower than that in the other Peltier modules. Consequently, the cooling effect of the Peltier module decreases, and therefore the temperature of the absorber surface of the Peltier module rises. Therefore, applying the same voltage to multiple Peltier modules means acting in a direction that unifies the temperature of the absorber surface, which means acting in a direction that unifies the temperature of the absorber plate. Therefore, if current is supplied to multiple Peltier modules arranged in the direction of movement of the floating stage 1 through a parallel circuit, it is possible to achieve uniformity of the absorber plate temperature relative to the direction of movement of the floating stage 1.

[0067] When the heat-absorbing fins reach a uniform temperature along the moving direction of the floating stage 1, the same cooling capacity can be obtained regardless of the location of the floating stage 1. Therefore, even if the floating stage 1 is moved to another location after being in a biased location for a long time, the temperature of the floating stage 1 can be kept constant. Furthermore, depending on the use... Figure 1 The control principle described above allows the temperature of the floating worktable 1 to be kept constant even when the average heat generation of the floating worktable 1 changes, through feedback control.

[0068] [Example 2]

[0069] Figure 3 The structure and system of the worktable device according to the second embodiment of the present invention are shown. Furthermore, in the following description, parts with the same function will be labeled with the same reference numerals, thus omitting the description.

[0070] Figure 3The difference between this embodiment and the first embodiment is that, instead of applying the same voltage to multiple Peltier modules 7 through a single power supply unit, separate power supply units 12 to 14 are provided for each Peltier module. Since each power supply unit exists one-to-one with a Peltier module, the thermoelectric potential generated in each Peltier unit can be determined. That is, when power supply unit 12 supplies power with current I1 and voltage V1, the thermoelectric potential Vz1 of the Peltier module can be calculated using equation (5). The same applies to power supply units 13 and 14.

[0071] On the other hand, when controlling the temperature of the floating stage 1 using this structure, the controller 18 observes the difference between the measured temperature Ts and the target temperature Ts', and determines the target thermoelectric potential Vz. This target thermoelectric potential is assigned to all Peltier modules as the same target value. Based on this, each power supply unit 12-14 operates current so that the thermoelectric potential in the operating state becomes the target value. If such current operation is performed, the thermoelectric potential of all Peltier modules is the same, and temperature uniformity can be achieved with higher precision compared to the case of Embodiment 1. Therefore, the temperature variation of the floating stage 1 becomes smaller, thermal deformation is further reduced, thereby improving positional accuracy.

[0072] [Example 3]

[0073] Figure 4 This section illustrates the structure and system of the stage device according to a third embodiment of the present invention. In this embodiment, the temperature of the heat absorber plate under the responsibility of each Peltier module is measured. The current of each Peltier module is controlled based on the difference between the measured temperature of each heat absorber plate and the temperature of the target heat absorber plate. In this case, controllers 19 to 21 are provided to determine the current of each Peltier module. In addition, when controlling the temperature of the floating stage 1, controller 22 determines the target temperature of the heat absorber plate. The individual controllers 19 to 21 are operated using the target fin temperature determined by controller 22. Using PID control in controllers 19 to 21 is also an effective means. Since the output current is determined by controllers 19 to 21 respectively, the internal structure of each power supply unit 15 to 17 of the Peltier module becomes easier.

[0074] [Example 4]

[0075] Figure 5 This section illustrates the structure and system of the worktable apparatus according to a fourth embodiment of the present invention. In this embodiment, it is a structure in which a cooling system for a lower worktable is added to the first embodiment. The cooling system for the floating worktable 1 is the same as in the first embodiment, and therefore its description is omitted here. Alternatively, the cooling structure of the lower worktable shown here can be combined with the cooling system of the floating system in embodiments 2 and 3.

[0076] To aid in cooling the lower worktable, in this embodiment, a heat sink 23 (also referred to as a "third fin") is installed on the bottom surface of the lower worktable 2. This heat sink 23 has a comb-like cross-sectional shape and extends in the direction of movement of the lower worktable 2. Additionally, a heat-absorbing fin 24 (also referred to as a "fourth fin") is positioned opposite the heat sink 23 and mounted on the base 4 across a Peltier module 25 (also referred to as a "second Peltier module"). Similar to the first embodiment, when this worktable device operates in a vacuum environment, the base 4 represents a vacuum container. Furthermore, multiple Peltier modules 25 are arranged in the direction of movement of the lower worktable 2 and are powered via a parallel circuit.

[0077] When the Peltier module 25 for cooling the lower worktable is in operation, the controller 26 can monitor the temperature measured by the temperature measuring unit (not shown) installed on the lower worktable 2, and apply feedback to make the temperature the target temperature for the lower worktable, and control the voltage for making the current flow through the Peltier module 25.

[0078] As in this embodiment, if the temperature of the lower worktable 2 is actively controlled, its temperature becomes more stable. Without active temperature control, when heat dissipation from the Peltier module 7 used for the floating worktable 1 increases, the temperature of the lower worktable 2 rises, resulting in increased heat transfer from the sliding unit 8 to the guide rail 3, leading to temperature equilibrium. On the other hand, if active temperature control is introduced for the lower worktable 2, its temperature remains constant even with fluctuations in heat dissipation from the Peltier module 7. This stabilizes the temperature of the heat dissipation surface of the Peltier module 7, allowing for a smooth increase in heat absorption when the current flowing through it increases. If the temperature of the heat dissipation surface of the Peltier module is unstable, the heat absorption is affected not only by changes in the current but also by fluctuations in the heat dissipation surface temperature, resulting in poor controllability of heat absorption. Therefore, when the temperature of the lower worktable 2 is actively controlled to achieve temperature stabilization, the controllability of the Peltier module 7 used for cooling the floating worktable improves, further contributing to the temperature stabilization of the floating worktable 1. Furthermore, the cooling control of the lower worktable 2 only controls it to its corresponding target temperature, so there is no need to consider the operating status of the upper worktable 1. Therefore, it can operate as an independent control system without causing interference or temperature instability between the two control systems.

[0079] [Example 5]

[0080] Figure 6 This describes the structure and system of the worktable device according to the fifth embodiment of the present invention. This embodiment also describes an additional cooling system for the lower worktable 2; therefore, the cooling system of the combined floating worktable can be any of the embodiments described in the first to third embodiments.

[0081] To assist in cooling the lower worktable, in this embodiment, a Peltier module 27 (equivalent to a "second Peltier module") is first installed on the bottom surface of the lower worktable 2, and a heat sink 28 (equivalent to the "third fin" mentioned above) is installed on its heat dissipation surface. Furthermore, a heat-absorbing fin 29 (equivalent to the "fourth fin" mentioned above) is installed facing the heat sink 28, and its back is mounted on the base 4. In this embodiment, since the Peltier module 27 for cooling the lower worktable 2 is installed on the moving side, it is not necessary to configure the Peltier module to cover the entire moving range of the lower worktable. The Peltier module 27 has its heat-absorbing surface mounted on the lower worktable body 2, absorbs heat from the lower worktable 2, and transfers heat to the heat sink 28. Therefore, the temperature of the heat sink 28 is higher than that of the lower worktable 2. On the other hand, the heat-absorbing fin 29 is mounted on the base 4, and therefore becomes approximately the same temperature as the base 4. Current cooling systems use low-temperature absorbers to induce radiative heat transfer, but in the cooling of the lower stage in this embodiment, radiative heat transfer is induced by high-temperature heat sinks. In this method, since the Peltier module 27 is mounted on the lower stage 2, its positional relationship with the Peltier module remains unchanged even if the lower stage moves, thus preventing changes in heat load. Therefore, even when using multiple Peltier modules, they do not need to be connected in parallel; they can be connected in series. When power is supplied via a series circuit, the voltage supplied from the power source increases, but the current remains low. Generally, a power supply with low current allows for a smaller device, thus offering the advantage of operating with low current.

[0082] Furthermore, in this embodiment, to prevent radiant heat from the heat sink 28 from returning to the lower worktable 2, the heat-absorbing sheet 29 is configured to cover both ends of the heat sink 28. Figure 6 In the structure shown, the heat sink 28 has one more fin than the heat absorber 29. This configuration prevents heat from returning. Furthermore, the surfaces of the heat sink 28 and the heat absorber 29 can be treated to increase emissivity, but the emissivity can be reduced only on the back side of the heat sink 28.

[0083] [Example 6]

[0084] Figure 7This describes the structure and system of the worktable device according to the sixth embodiment of the present invention. In this embodiment, cooling assistance for the lower worktable is performed passively without active control. A heat sink 31 is installed on the bottom surface of the lower worktable 2, and a heat absorber 32 is installed opposite it. The back of the lower worktable is cooled by a radiator 33. The radiator 33 allows refrigerant to flow internally, maintaining a constant temperature at the radiator inlet and operating at a constant flow rate. Therefore, the cooling capacity of the radiator 33 is not actively controlled; the heat transfer only varies over time due to the temperature change of the heat sink 31. A total heat load is applied to the lower worktable 2, consisting of the heat generated by the floating worktable 1, the power consumed by the Peltier module 7, and the heat generated by the lower worktable 2. Compared to heat dissipation solely through heat transfer from the sliding unit 8 to the guide rail 3, adding a path for heat dissipation to the radiator 33 reduces the temperature rise of the lower worktable 2, which also contributes to the temperature stabilization of the floating worktable 1.

[0085] In addition, the cooling aid using radiator 33 can also be used in combination with the fourth and fifth embodiments.

[0086] [Example 7]

[0087] Figure 8 This describes the structure and system of the worktable apparatus according to a seventh embodiment of the present invention. The difference between this embodiment and the first embodiment is that the lengths of the heat-absorbing plates 6 cooled by each Peltier module 7 are different. In the case of an apparatus where the ratio of the areas where the floating worktable 1 stays is approximately fixed, by increasing the arrangement density of the Peltier modules arranged in areas with a high staying ratio, the heat load on the Peltier modules can be made more uniform. Figure 8 In the embodiment described, it is assumed that the floating stage 1 has a high rate of staying in the central part during its movement range. Under this assumption, the heat load applied to the central Peltier module becomes higher. Therefore, the length of the heat absorber fin 6' cooled by the central Peltier module is shortened, and instead, the length of the left and right heat absorber fins 6 is lengthened. With the operating mode of the floating stage determined and the dwell ratio known in advance, the hardware design can be made accordingly to ensure a uniform heat load applied to the Peltier module, thereby achieving uniform heat load and temperature of the heat absorber fins. With such a structure, the same cooling capacity can be obtained regardless of where the floating stage 1 is located. Furthermore, in Figure 8 In this circuit, multiple Peltier modules are connected in parallel, but current can also be supplied through a series circuit.

[0088] Explanation of reference numerals in the attached figures

[0089] 1. Floating worktable (upper worktable)

[0090] 2 Lower workbench

[0091] 3. Guide rails for the lower worktable

[0092] 4. Base of the worktable assembly (vacuum container)

[0093] 5. Heat sinks for the floating worktable

[0094] 6. Heat-absorbing fins for the floating worktable

[0095] 7. Peltier modules for the floating worktable (multiple modules arranged in an array)

[0096] 8. Sliding unit that slides on the guide rail

[0097] 10 Power supply unit for supplying current to the Peltier module

[0098] 11. Controller for controlling the temperature of the floating worktable

[0099] 12–17 Power supply units for supplying current to individual Peltier modules

[0100] 18. Controller for controlling the temperature of the floating worktable (via thermoelectric potential)

[0101] 19-21 Controllers that determine the current of a single Peltier module

[0102] 22. Controller for controlling the temperature of the floating worktable (via fin temperature type)

[0103] 23. Heat sink for the lower workbench

[0104] 24. Heat-absorbing fins for the lower workbench

[0105] 25 Peltier module for lower workbench

[0106] 26. Controller for controlling the temperature of the lower worktable

[0107] 27. Peltier module for the lower workbench (type located on the side of the workbench)

[0108] 28. Heat sink for the lower workbench

[0109] 29. Heat-absorbing fins for the lower workbench

[0110] 30 Controller for controlling the temperature of the lower worktable

[0111] 31. Heat sink for the lower workbench

[0112] 32 Heat-absorbing fins for the lower workbench

[0113] 33 Radiators using refrigerant

[0114] 100 indicates the arrow pointing in the direction of movement of the floating worktable.

[0115] 101 indicates the arrow pointing in the direction of movement of the lower workbench.

Claims

1. A worktable device, comprising: The first worktable moves in a straight line. The first fin extends in the direction of linear movement of the first worktable and has a comb-like cross-sectional shape. The second worktable has a second fin arranged opposite to the first fin and is fixed when viewed from the first worktable; as well as The heat transfer mechanism performs heat transfer while maintaining a non-contact relationship between the first fin and the second fin. Its features are, A first Peltier module is located between the second fin and the second worktable. One heat transfer surface of the first Peltier module contacts the second fin, and the other heat transfer surface contacts the second worktable. The workbench device has a control unit that controls the temperature of the second fin via the first Peltier module, thereby controlling the heat transfer generated between the first fin and the first workbench side.

2. The workbench device according to claim 1, characterized in that, There are multiple first Peltier modules in the second worktable, and multiple first Peltier modules are arranged in the direction of linear movement of the first worktable. The control unit adjusts the current flowing through each of the multiple first Peltier modules so that the temperature of the second fins on the second worktable is approximately uniform relative to the direction of linear movement of the first worktable.

3. The workbench device according to claim 2, characterized in that, The control unit uses the thermoelectric potential generated by the temperature difference between the heat absorption surface and the heat dissipation surface of each of the multiple first Peltier modules to control the temperature of the second fins of the second worktable to make the temperature of the second fins approximately uniform.

4. The workbench device according to claim 3, characterized in that, The control unit has a parallel circuit for supplying current to a plurality of first Peltier modules, and the control unit controls the driving of each of the plurality of first Peltier modules with approximately the same voltage.

5. The workbench device according to claim 2, characterized in that, The workbench device has a temperature measuring unit for measuring the temperature of the first workbench. The control unit controls the current flowing through the multiple first Peltier modules, so that the temperature of the first workbench measured by the temperature measurement unit becomes a preset target temperature, and controls the temperature of the second fin of the second workbench to change.

6. The workbench device according to claim 1, characterized in that, The second workbench becomes a lower workbench that can move along with the first workbench. The first worktable can move in two dimensions because its movement direction is approximately orthogonal to that of the second worktable.

7. The workbench device according to claim 6, characterized in that, The fixing part, as seen from the second worktable, has a third fin with a comb-like cross-sectional shape. The fixing part is configured to have a fourth fin facing the third fin, and the heat transfer between the third fin and the fourth fin promotes the transfer of heat from the second worktable to the fixing part.

8. The workbench device according to claim 7, characterized in that, The workbench device includes a second Peltier module for promoting heat transfer between the second workbench and the fixed part. The control unit controls the second Peltier module so that the temperature of the second workbench becomes the set target temperature.

9. The worktable device according to claim 8, characterized in that, The first worktable is used in a state where it is floating relative to the second worktable. The second worktable moves while in contact with the guide rail provided on the fixed part.

10. The workbench device according to claim 9, characterized in that, The first worktable is a magnetically levitated worktable that is lifted from the second worktable by magnetic force, and the first worktable moves linearly by a linear motor, which is a moving-coil linear motor.

11. A charged particle beam device, characterized in that, A stage device according to any one of claims 1 to 10 is provided in a housing that is kept in a vacuum. The stage device is used for positioning a sample and has a charged particle beam irradiation section for irradiating the sample with a charged particle beam.

Images