JP3207871B2 - Wafer support device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray exposure apparatus using synchrotron radiation as a light source, and more particularly to a wafer supporting apparatus for supporting a wafer.

[0002]

2. Description of the Related Art Very fine patterns, for example, 0.25 μm
In an X-ray exposure apparatus for exposing a fine pattern of m or less, synchrotron radiation having an X-ray intensity of about 1000 (W / m ² ) is used as exposure light. The temperature of the wafer to be subjected to the exposure processing is increased due to the irradiation of the intense light, and thermal distortion may be caused by the increased temperature. For this reason, in a wafer support device used in this type of exposure apparatus, a wafer chuck for restraining a wafer is provided with a temperature adjustment mechanism, and the temperature is indirectly adjusted by raising the temperature of the wafer. It was configured to suppress thermal distortion of the wafer itself.

As such a mechanism for adjusting the temperature of the wafer chuck, there is one disclosed in Japanese Patent Application Laid-Open No. 2-183514. In this device, a temperature sensor is provided in the wafer chuck because the responsiveness of temperature control is better than that of cooling using cooling water, and a peltier attached to the wafer chuck is provided in accordance with a detection signal of the temperature sensor. The element is being controlled.

FIG. 7 is a view showing a structure of a wafer chuck using the above-mentioned Peltier device. In this conventional example,
The suction block 701 holding the wafer is moved to the stage 70 via a Peltier element 704 and a cooling block 706 in this order.
8 attached. A groove 702 is formed on the suction surface of the suction block 701, and a vacuum suction pipe 703 communicating with the groove 702 is provided inside. In addition, a temperature sensor 719 is attached to a part thereof, and outputs a signal indicating the detected temperature to the outside via a signal line 720. The Peltier element 704 has a structure in which a semiconductor thermoelectric element 718 is sandwiched between ceramic plates (alumina) 716. An electrode 717 is formed on the surface of the ceramics plate 716 on the semiconductor thermoelectric element 718 side, and the temperature is adjusted by the amount of current supplied through the current supply line 724.
A channel 712 is formed inside the cooling block 706, and the channel 712 communicates with the pipe 707.

[0005] The cooling block 706 is cooled by cooling water flowing through a flow path 712 in the cooling block 706 through a pipe 707. At this time, if the flow rate of the cooling water is too low, the temperature difference between the cooling water and the wall surface of the flow path 712 increases,
Thermal deformation occurs in the cooling block 706, and the entire wafer chuck is deformed.

FIG. 8 shows the result of measuring the relationship between the flow rate of the cooling water and the vibration when the cross-sectional shape of the flow path 712 is rectangular. The flow rate of the cooling water is set to 0.15 (m / sec) in which the influence of the vibration shown in FIG. 8 can be ignored, and aluminum nitride (hereinafter, referred to as AlN) having a thickness of 5 mm is used as a material for forming the adsorption block 701. , Cooling block 70
6 was made of AlN, and the distance between the surface of the cooling block 706 and the flow path 712 was 5 mm.
The channel has a rectangular cross section and a heat transfer coefficient of 300 (W / m ² .
In the case of K), the temperature difference between the cooling water and the wall surface of the flow path 712 for a heat flow density of 1000 (W / m ² ) is approximately 3 ° C. Here, as shown in FIG.
In the structure in which the Peltier element 704 is arranged between the Peltier element 704 and the suction block 701, the displacement occurs on the back surface of the Peltier element 704 without considering the thermal energy supplied to the Peltier element 704.

The displacement of the Peltier element 704 is x,
When calculated by a simple first-order approximation in the y-direction, the linear expansion coefficient of alumina as a constituent material of the ceramics plate 716 is 7E−
6) × (temperature rise value 3 ° C.) × (length of one side of exposure angle of view 3)
0 mm), that is, expands by 0.6 μm, and gives the suction block 701 considerable displacement. As a result, the wafer attached to the suction block 701 is also deformed, and the printing accuracy is deteriorated.

When the length between the cooling surface and the surface of the wafer chuck is short, the heat diffusion to the xy plane is small, so that a plurality of angles of view are exposed on one wafer. In the exposure by the repeat method, during the exposure, the temperature of only the angle of view irradiated with X-rays increases, and the temperature of the other angles of view hardly increases. Therefore, in order to prevent the wafer from being thermally strained by restraining the wafer with a wafer chuck whose temperature has been adjusted with high precision using a Peltier element, a pair of a temperature sensor and a Peltier element must be provided in at least one angle of view. It is necessary that each Peltier element is controlled independently of the other Peltier elements by receiving the signals of the pair of temperature sensors.

FIG. 9 is a diagram for explaining a problem caused by controlling a plurality of Peltier elements by a detection signal of one temperature sensor.

A suction block 701 for holding a wafer (not shown) exposed by a heat flux 901 is temperature-controlled by _three Peltier elements 704 _{1 to} 704 ₃ .
The temperature sensor 719 is attached substantially at the center of the suction block 701, and a signal indicating the detected temperature is supplied to the converter 92.
1 to the controller 922. Controller 922 to perform the current supply to the Peltier device controller 923 based on the temperature detected by the temperature sensor 719, controls the temperature of the Peltier devices 704 _{1 to 704 3.}

As shown in FIG. 9A, when the temperature sensor 719 is not arranged at the exposure angle of view where the heat flux 901 is incident, the angle of view whose temperature is increased by exposure may not be cooled. As a result, exposure view angle and the Peltier devices 704 ₁ arranged in the region is thermally expanded, or baking line width wider than the mask pattern, the spacing between the pattern becomes wider.

[0012] As shown in FIG.
If the temperature sensor 719 is arranged at the exposure field angle
The unexposed angle of view cools down more than necessary
Sometimes. As a result, the non-exposure angle of view and the
Each peltier element 704 ₁, 704_ThreeHeat shrinks the mass
And the exposure angle of view is displaced.

[0013]

In the above-described conventional wafer supporting apparatus, when the cooling water is flowed at a flow rate at which the influence of the vibration can be ignored, the suction block is displaced and the wafer baking accuracy is deteriorated. There is.

Further, a pair of temperature sensors and a Peltier element are arranged at at least one angle of view, and each Peltier element needs to be configured to receive signals from the pair of temperature sensors and be controlled independently of the other Peltier elements. Therefore, there is a problem that the configuration and control are complicated.

The present invention has been made in view of the above-mentioned problems of the prior art, and does not cause displacement of the suction block even at a flow rate of cooling water in which the influence of vibration can be neglected. It is another object of the present invention to realize a wafer support device having a simplified configuration.

[0016]

According to the present invention, there is provided a wafer supporting apparatus comprising: a suction means for holding a wafer; and a Peltier element for controlling the temperature of the suction means. and the heat pipe on the other side of the Peltier element being in contact with one surface, the heat pipes
And a cooling block for cooling .

A wafer support apparatus according to another embodiment of the present invention
Includes suction means for holding a wafer, comprising: a temperature sensor for detecting the temperature of the adsorber unit, a Peltier element for adjusting the temperature of the adsorber unit, based on the detected temperature of the temperature sensor the in a wafer supporting apparatus temperature control is performed in the adsorption means, and the heat pipe to the other surface of the Peltier element that is in contact with the adsorption means and the one surface, the
And a cooling block for cooling the heat pipe .

Further, in any of the above cases,
A heat pipe may be provided between the Peltier device and the suction unit.

[0019]

In a heat pipe having a high thermal conductivity and a low thermal resistance, heat is quickly diffused. For this reason, the heat flow incident on one surface (heat receiving surface) of the heat pipe via the suction means and the Peltier element at the time of exposure is diffused over the entire surface of the other surface (cooling surface). The heat flow incident on one surface (heat receiving surface) of the heat pipe is diffused over the entire surface of the other surface (cooling surface) and then cooled by the Peltier element, so that cooling is performed efficiently.

If each of the temperature sensor and the Peltier element is mounted at a position where the temperature is averaged by the heat pipe, it is only necessary to provide a pair of these in one heat pipe. Simplified.

[0021]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing the structure of a first embodiment of the present invention, and FIG. 2 is a sectional view thereof. The suction block 101, which is a suction means for holding a wafer, is a heat conductive material and a low thermal expansion material, and is made of a material that can be easily processed. And is attached to the stage 108. The stage 108 includes an actuator 109,
It is attached to the fixed part 111 via each hinge spring 110, and is finely movable in the x direction. Originally, the stage for high-precision positioning has a structure that can finely move in six axes of each of the x, y, and z directions and its rotation direction. However, here, only the structure that finely moves in the x direction is shown.

As shown in FIG. 2, a temperature sensor 119 for detecting the temperature of the suction block 101 is attached to the suction block 101. A temperature sensor 119 such as a platinum resistance thermometer is attached to the end of the suction block 101, which is not affected by the exposure light and whose temperature is averaged by the heat pipe 105, and indicates the detected temperature. The signal is input to the converter 121 via the signal line 120. The signal indicating the detected temperature converted into a digital signal by the converter 121 is input to the controller 122 via the communication cable 125. Controller 12
2 outputs a signal indicating the set temperature of the Peltier element 104 based on the temperature detected by the temperature sensor 119 to the Peltier element controller 123 via the communication cable 125, and the Peltier element controller 123 determines whether the temperature of the Peltier element 104 is above. A current is supplied to the Peltier element 104 so as to reach the set temperature.

A groove 102 is formed on the suction surface of the suction block 101.
Is formed therein, and a vacuum suction pipe 103 communicating with the groove 102 is provided therein. As described above, the temperature sensor 119 is attached to a part thereof, and outputs a signal indicating the detected temperature to the outside via the signal line 120.

The Peltier element 104 is a semiconductor thermoelectric element 11
8 is sandwiched between ceramic plates (alumina) 116. Semiconductor thermoelectric element 118 of ceramics plate 116
An electrode 117 is formed on the side of the current supply line 1.
The temperature is controlled by the amount of current supplied via 24.

The heat pipe 105 is placed in a container 113,
Wick 114 for generating capillary action to wet the inner surface of container 113 with hydraulic fluid and saturated vapor 1 as hydraulic fluid
15 is confined. A method of manufacturing this type of heat pipe is described in, for example, Japanese Patent Application Laid-Open No. 58-096992, and is not specifically described here since many modifications have been proposed.

Inside the cooling block 106, a pipe 10
A cooling water passage 112 having a rectangular cross section communicating with the passage 7 is formed. The cooling block 106 is cooled by cooling water flowing through a flow path 112 in the cooling block 106 through a pipe 107.

Next, the heat transfer operation in this embodiment will be described.

When the exposure light is irradiated on the wafer held by the suction block 101 of this embodiment, the heat generated by the irradiation hardly spreads on the xy plane and the heat pipe 105 provided in the z direction. Conveyed to. Since the heat pipe 105 has a very high thermal conductivity and a low thermal resistance, the heat transmitted to the heat pipe 105 is quickly diffused to the xy plane, and efficient cooling using the entire cooling surface of the heat pipe 105 is performed. Is made.

Hereinafter, specific numerical values will be described.

Groove 10 for vacuum suction of suction block 101
X-rays are radiated from the z direction to the wafer adsorbed by the wafer 2.
One view angle of the exposure area to be printed on the wafer is 3 cm square (9
cm ^Two), The incident heat flow density of X-rays is 1000 (W / m^Two),
Cooling side of heat pipe 105 (cooling block 106 side)
Area of 15cm square (225cm^Two). Wafer,
Each of the suction block 101 and the Peltier element 104
Since it is thin, the heat generated by the irradiation is xy
Almost no diffusion on a plane. Because of this, heat pipe
Almost 100 on the heat receiving side of 105 (Peltier element 104 side)
0 (W / m^TwoA heat flow having a heat flow density of (2) is incident.

As described above, since the heat transmitted to the heat pipe 105 is quickly diffused to the xy plane, the heat flow density on the cooling side of the heat pipe 105 is 40 (W / m ² ) (= 1).
000 × 9/225).

The amplitude of the vibration generated by flowing the cooling water is suppressed to 0.01 μm or less when the flow rate of the cooling water is 0.15 (m / sec) or less.

The flow rate of the cooling water is 0.15 (m / sec), and the heat transfer coefficient of the
When the temperature is 00 (W / m ² .K), the temperature rise of the cooling water and the wall surface of the flow path 112 for a heat flow density of 40 (W / m ² ) can be suppressed to approximately 0.1 ° C. At this time, the Peltier element 1
04, the displacement amount in the xy direction on the heat pipe 105 side is x,
When calculated by a simple first-order approximation in the y-direction, (linear expansion coefficient 7E−
6) × (temperature rise value 0.1 ° C.) × (length of one side of the exposure angle of view 30 mm), that is, a very small 0.02 μm expansion, and the amount of displacement of the suction block 101 caused by this is extremely small. Becomes

In this embodiment, as shown, the area of the heat pipe 105 on the heat receiving side is larger than the area of the wafer suction section of the suction block 101, and the back surface of the wafer suction section is a heat pipe. Since the structure is always cooled by the wick of 105, there is no possibility of poor cooling.

In the present embodiment, it is not necessary to provide a pair of temperature sensors and a Peltier element for one angle of view as in the prior art, but only for one heat pipe. It was simplified and the control was easy.

FIG. 3 is a diagram showing the configuration of the second embodiment of the present invention.

In this embodiment, the order of the Peltier element 104 and the heat pipe 105 in the z direction in the first embodiment is changed, and the Peltier element 304 and the heat pipe 305 are respectively replaced. The other configuration is the same as that of the first embodiment, and thus the same reference numerals as those in FIG.

With such a configuration, the displacement of the suction block 101 caused by exposure can be reduced as in the first embodiment. In addition, temperature sensor 1
Since 19 may be provided between the wafer and the Peltier element 304, in the present embodiment,
For example, the heat pipe 305 may be provided.

FIG. 4 is a diagram showing the configuration of the third embodiment of the present invention.

In the present embodiment, the wafer suction block in the first and second embodiments is used as a component of a heat pipe.

[0042] In this embodiment, the container portion of the heat pipe, which is formed by a plurality of constituent members 402 ₁ to 402 _3, each surface facing the inside of these containers of the components 402 _{1-402 3} wick forming surface 403 ₁ -
There is a 403 _3. The wick can be formed by forming a groove having a depth of not more than mm in, for example, a lattice shape by using machining such as a dicing saw or etching or dry etching. Was.

_On the outer surface of the _first component 4021, a wafer suction surface 40 as suction means for partially holding a wafer is provided.
1 is formed, and a Peltier element 404 is attached to a part of the outer surface of the _third component 4023. In the present embodiment, the first component 402 _first wafer suction surface 4
01 is a heat receiving surface, and the back surface of the Peltier element 404 of the _third component 4023 is a cooling surface.

As shown, the first component 402 ₁
Covers the entire surface of the wafer suction surface 401,
1 is configured such that a wick is always formed on the back surface. Thus, the back surface of the wafer suction surface 401 as being always cooled by the working fluid 404 in the wick wick forming surface 403 _1, which is assumed to cooling failure does not occur. Also, the working fluid 40 contained in the container
4 is positioned below the outer periphery of the wafer suction surface 401, and a vertical chuck, that is, an exposure apparatus that suctions a wafer so that the irradiation direction of exposure light is substantially orthogonal to gravity does not cause cooling failure. I have. The heat pipe configured as described above is supported by the wafer chuck support block 408. Peltier element 404
Is provided with a cooling block 405, and is cooled by cooling water supplied via a pipe 407 to a flow path 406 provided therein. This Peltier element 404
Is controlled by calculating the output of a temperature sensor (not shown) by a controller (not shown) and supplying an appropriate current to the Peltier element 404 from a Peltier element controller (not shown).

The number of the temperature sensors and the number of the Peltier elements used in this embodiment may be one or more.
This is because the temperature distribution of the heat pipe is substantially uniform except that the temperature of the heat receiving surface is high and the temperature of the cooling surface is low. In the example shown in FIG. 4, the temperature in the hatched portion becomes uniform, and the temperature sensor may be provided in any of these portions.

As described above, in the present embodiment in which the wafer suction block is a component of the heat pipe,
The structure could be further simplified as compared with the second embodiment.

FIG. 5 is a diagram showing the configuration of the fourth embodiment of the present invention.

This embodiment is different from the third embodiment shown in FIG. 4 in that a pillar 501 is provided in a heat pipe constituted by a plurality of structural members 402 _{1 to} 402 ₃ . This pillar 50
By providing 1, the heat pipe is prevented from being deformed by the differential pressure between the saturated vapor pressure of the working fluid 404 in the heat pipe and the atmospheric pressure outside the heat pipe. In this embodiment, a temperature sensor may be provided in the above-mentioned column 501.

In each of the above embodiments, the heat pipe has been described as being integrally formed in a rectangular shape as seen from the incident direction of the exposure light, like the heat pipe 601 shown in FIG. , The heat pipe 602 shown in FIG. 6B, and the heat pipe 602 shown in FIG.
Like the divided heat pipe 603, a temperature sensor and a Peltier element may be provided for each of the divided heat pipes, and the shape is not limited. When the heat pipe is divided into a plurality of parts, the xy plane of each divided heat pipe becomes smaller, so that the supply of the working fluid becomes faster, and the effect of the present invention is further improved.

By dividing the heat pipe into a plurality of parts, in the case of a conventional heat pipe structure in which the working fluid is present in the exposure area (for example, as shown in FIG. 6C), Alternatively, only the storage section for the hydraulic fluid may be provided outside the exposure area.

[0051]

Since the present invention is configured as described above, it has the following effects.

According to the first and second aspects of the present invention, cooling can be performed efficiently, and no displacement occurs in the suction block even at a flow rate at which the influence of vibration can be ignored. There is an effect that can be.

According to the third and fourth aspects, it is not necessary to provide a pair of temperature sensors and a Peltier element for one angle of view, so that the apparatus configuration is simplified and the control is simplified. There is also an effect that can be made easier.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a first exemplary embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration of a third exemplary embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of a fourth embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of division of a heat pipe.

FIG. 7 is a cross-sectional view showing a configuration of a conventional example.

FIG. 8 is a diagram illustrating a relationship between a flow rate of cooling water and a displacement amount of an adsorption block.

9A and 9B are diagrams showing an exposure state of a conventional example, in which FIG. 9A shows a state in which a temperature sensor is not arranged at an exposure angle of view at which a heat flux enters, and FIG. 9B shows an exposure state at which a heat flux enters. The state where the temperature sensor is arranged at the angle of view is shown.

[Explanation of symbols]

 101 Suction block 102 Groove 103, 107 Piping 104, 304, 404 Peltier element 105, 305 Heat pipe 106 Cooling block 108 Stage 109 Actuator 110 Elbow spring 111 Fixed part 112 Flow path 113 Container 114 Wick 115 Saturated vapor 116 Ceramics plate 117 Electrode 118 semiconductor thermoelectric element 119 temperature sensor 120 signal line 121 converter 122 controller 123 Peltier element control unit 124 current supply line 125 communication cable

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027 H01L 21/68

Claims (6)

(57) [Claims] 1. A wafer supporting apparatus comprising: a suction means for holding a wafer; and a Peltier element for controlling the temperature of the suction means, wherein the other surface of the Peltier element is in contact with the suction means on one surface. Heat pipe and cool the heat pipe
A wafer support device provided with a cooling block . 2. A wafer support apparatus comprising: a suction device for supporting a wafer; and a Peltier device for controlling the temperature of the suction device, wherein a heat pipe is provided between the Peltier device and the suction device. A wafer support device, characterized in that: 3. A suction device for holding a wafer, a temperature sensor for detecting the temperature of the suction device, and a Peltier element for controlling the temperature of the suction device, wherein the temperature detected by the temperature sensor is In the wafer supporting apparatus, the temperature of the suction unit is controlled based on the heat pump, and the other surface of the Peltier element that is in contact with the suction unit on one surface is provided with a heat pipe and the heat pipe is cooled.
A wafer support device provided with a cooling block . 4. A suction device for holding a wafer, a temperature sensor for detecting the temperature of the suction device, and a Peltier element for controlling the temperature of the suction device, wherein the temperature detected by the temperature sensor is A wafer support device in which a temperature control of the suction unit is performed based on a heat pipe, wherein a heat pipe is provided between the Peltier element and the suction unit. 5. The wafer support device according to claim 1, wherein the heat pipe has a space provided with a wick. 6. The wafer supporting apparatus according to claim 1, wherein said suction means vertically supports the wafer to be exposed.