Electrostatic chuck device and cooling plate

Abstract

To equalize the temperature of an object adsorbed by an adsorption plate.SOLUTION: An electrostatic chuck device 100, which adsorbs an object by an electrostatic force, comprises an adsorption plate 2 which has an adsorption surface for adsorbing the object W on a front side, and a cooling plate 3 which is provided on the back side of the adsorption plate 2 and which has an inner channel 31 where a coolant flows. The inner channel 31 assumes a channel shape in which identically-patterned channel elements 31x are regularly connected in a plan view.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an electrostatic chuck device and a cooling plate.

Background Art

[0002] Conventionally, in the semiconductor manufacturing process, an electrostatic chuck device has been used to fix a wafer in a vacuum chamber. As shown in Patent Document 1, this electrostatic chuck device includes a suction plate that adsorbs an object by electrostatic force, and a metal cooling plate that contacts the back surface of the suction plate. A refrigerant flows through an internal flow path formed in the cooling plate to cool the wafer adsorbed on the suction plate. In this way, the surface temperature distribution of the wafer is made uniform.

[0003] Here, the cooling plate is provided with an introduction port for introducing the refrigerant into the internal flow path and a discharge port for discharging the refrigerant. Since the vicinity of the introduction port is preferentially cooled by the refrigerant, it becomes a low-temperature region, and as the refrigerant flows through the internal flow path, its temperature increases. Therefore, the vicinity of the discharge port where the refrigerant is discharged becomes a high-temperature region. That is, a temperature gradient is generated in the cooling plate. If this temperature gradient becomes large, the wafer adsorbed on the suction plate may crack due to thermal stress, and the suction plate may also be damaged.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, the present invention has been made to solve the above-described problems, and an object thereof is to reduce the temperature gradient of the adsorption plate and make the temperature of the object adsorbed on the adsorption plate uniform.

Means for Solving the Problems

[0006] That is, an electrostatic chuck device according to the present invention is an electrostatic chuck device that adsorbs an object by electrostatic force, and includes an adsorption plate having an adsorption surface for adsorbing the object on the surface side, and a cooling plate provided on the back surface side of the adsorption plate and having an internal flow path through which a refrigerant flows. The internal flow path has a flow path shape in which flow path elements of the same pattern are regularly connected in a plan view.

[0007] In such an electrostatic chuck device, since the internal flow path of the cooling plate has a flow path shape in which flow path elements of the same pattern are regularly connected in a plan view, it is possible to configure the flow to meander between the central portion side (radial inner side) and the outer peripheral portion side (radial outer side) of the cooling plate. As a result, the temperature difference between the central portion side and the outer peripheral portion side and the temperature difference in the circumferential direction can be reduced, and the temperature gradient of the entire adsorption surface of the adsorption plate can be made small. As a result, the temperature of the object adsorbed on the adsorption plate can be made uniform. In addition, by adopting a flow path shape in which flow path elements of the same pattern are regularly connected, the design and processing become easier, and the mechanical strength of the cooling plate can be increased.

[0008] As a specific embodiment, the internal flow path communicates with a refrigerant introduction port and a refrigerant discharge port of the cooling plate, and it is desirable that the change in the radial distance from the central portion of the cooling plate increases and the change in the radial distance from the central portion decreases repeatedly as the refrigerant flows from the refrigerant introduction port toward the refrigerant discharge port. With this configuration, since the internal flow path communicating from the refrigerant introduction port to the refrigerant discharge port repeatedly increases and decreases in the radial distance in the cooling plate, the temperature difference between the central portion side and the outer peripheral portion side can be reduced, and the temperature gradient of the entire adsorption plate can be made small.

[0009] As a specific embodiment, it is desirable that the flow path element has a curved flow path portion, a bent flow path portion, or a flow path portion bent in the middle. With this configuration, since the internal flow path communicating from the refrigerant introduction port to the refrigerant discharge port is curved, bent, or folded, the temperature difference between the central portion side and the outer peripheral portion side can be reduced, and the temperature gradient of the entire adsorption plate can be made small.

[0010] As a specific embodiment, it is desirable that the internal flow path has a meandering flow path shape by regularly connecting the flow path elements. With this configuration, since the internal flow path communicating from the refrigerant introduction port to the refrigerant discharge port is meandering, the temperature difference between the central portion side and the outer peripheral portion side can be reduced, and the temperature gradient of the entire adsorption plate can be made small.

[0011] As a specific embodiment of the internal flow path, it is desirable that the internal flow path has a shape that can be represented by a periodic function. By using such a periodic function in this way, the flow path design for reducing the temperature gradient of the cooling plate can be simplified.

[0012] As a specific embodiment of the internal flow path, it is desirable that the internal flow path has a shape that can be represented by a Fourier series. By using such a Fourier series in this way, for example, a meandering flow path can be formed on the inner and outer sides in the radial direction of the cooling plate, and the flow path design for reducing the temperature gradient of the cooling plate can be simplified.

[0013] As a specific embodiment of the internal flow path, it is desirable that the internal flow path has a fractal shape. By using such a fractal shape, for example, it is possible to form meandering flow paths on the inner and outer sides in the radial direction of the cooling plate, and it is possible to simplify the flow path design for reducing the temperature gradient of the cooling plate.

[0014] As a specific embodiment of the internal flow path, it is desirable that the internal flow path has a shape that can be represented by a Gosper curve or a Minkowski curve. By using such a Gosper curve or Minkowski curve, for example, it is possible to form meandering flow paths on the inner and outer sides in the radial direction of the cooling plate, and it is possible to simplify the flow path design for reducing the temperature gradient of the cooling plate.

[0015] In addition, the cooling plate according to the present invention is a cooling plate used in an electrostatic chuck device that adsorbs an object by electrostatic force, has an internal flow path through which a refrigerant flows, and the internal flow path has a flow path shape in which flow path elements of the same pattern are regularly connected in a plan view.

Effects of the Invention

[0016] Thus, according to the present invention, it is possible to reduce the temperature gradient of the adsorption plate and make the temperature of the object adsorbed on the adsorption plate uniform.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0018] Hereinafter, an embodiment of an electrostatic chuck device according to the present invention will be described with reference to the drawings. In addition, for any of the figures shown below, for the sake of clarity, they are schematically drawn with appropriate omissions or exaggerations. The same reference numerals are given to the same components, and the description thereof will be omitted as appropriate.

[0019] <Configuration of Electrostatic Chuck Device> The electrostatic chuck device 100 of the present embodiment is provided, for example, in a vacuum chamber of a semiconductor manufacturing apparatus using plasma, and adsorbs a wafer as an object by electrostatic force in the vacuum chamber.

[0020] Specifically, as shown in FIG. 1, the electrostatic chuck device 100 includes an adsorption plate 2 having an adsorption surface for adsorbing the wafer W on the surface side, a cooling plate 3 provided on the back surface side of the adsorption plate 2 and having one or a plurality of internal flow paths through which a refrigerant flows, and a refrigerant supply mechanism 4 for supplying the refrigerant to the cooling plate 3.

[0021] The adsorption plate 2 is, for example, a circular flat plate made of an insulating material such as ceramics or glass. An internal electrode (not shown) is embedded in the adsorption plate 2, and a voltage is applied by an external power source. When a voltage is applied to the internal electrode, a dielectric polarization phenomenon occurs in the adsorption plate 2, and the surface side of the adsorption plate 2 becomes the adsorption surface. Note that the adsorption plate 2 is, for example, a bipolar type, but is not limited thereto and may be a unipolar type.

[0022] The cooling plate 3 is a circular flat plate-shaped metal formed body having a hollow structure thicker than the adsorption plate 2. The cooling plate 3 of the present embodiment can be manufactured, for example, by 3D printing or additive manufacturing using metal particles containing titanium (Ti).

[0023] Inside this cooling plate 3, one or a plurality of internal flow paths 31 through which a refrigerant flows are formed. This internal flow path 31 is connected to a refrigerant supply mechanism 4 outside the cooling plate 3 and is configured such that the refrigerant circulates between the cooling plate 3 and the refrigerant supply mechanism 4. Note that each of the refrigerant introduction port P1 and the refrigerant discharge port P2 that connect the internal flow path 31 and the refrigerant supply mechanism 4 may be one or a plurality according to the configuration of the internal flow path 31.

[0024] The refrigerant supply mechanism 4 includes a refrigerant introduction pipe 41 connected to the refrigerant introduction port P1 of the cooling plate 3, a refrigerant discharge pipe 42 connected to the refrigerant discharge port P2, a cooler 43 such as a chiller unit that cools the refrigerant, and a circulation pump 44 that circulates the refrigerant. This refrigerant supply mechanism 4 performs temperature control of the refrigerant so that, for example, a refrigerant at -80°C or lower is supplied to the internal flow path 31 of the cooling plate 3.

[0025] <Specific configuration of the internal flow path 31> Then, as shown in FIGS. 2 and 3, the one or a plurality of internal flow paths 31 formed in the cooling plate 3 of the present embodiment have a flow path shape in which flow path elements 31x of the same pattern are regularly connected in a plan view. That is, the internal flow path 31 has a portion in which the flow path elements 31x of the same pattern are regularly and continuously connected in the flow path from the refrigerant introduction port P1 to the refrigerant discharge port P2.

[0026] Here, the flow path elements 31x of the same pattern may have different arrangement positions and arrangement angles on the cooling plate 3 as long as their shapes and sizes are the same or substantially the same. Further, the flow path element 31x is bent or flexed at least once in the direction (radial direction) from the central portion (inner side in the radial direction) to the outer peripheral portion (outer side in the radial direction) of the cooling plate 3.

[0027] Then, the internal flow path 31 has a meandering flow path in the direction from the center (radial inner side) to the outer periphery (radial outer side) of the cooling plate 3 in the flow path from the refrigerant introduction port P1 formed at the center of the cooling plate 3 to the refrigerant discharge port P2 formed at the outer periphery of the cooling plate 31, where a plurality of flow path elements 31x are regularly connected. Further, the internal flow path 31 repeats a change in which the radial distance from the center increases and a change in which the radial distance from the center decreases as it goes from the refrigerant introduction port P1 to the refrigerant discharge port P2. Note that a configuration may also be adopted in which the refrigerant introduction port P1 is formed at the outer periphery of the cooling plate 3 and the refrigerant discharge port P2 is formed at the center of the cooling plate 3.

[0028] Here, the internal flow path 31 may have a flow path shape in which flow path elements 31x of the same pattern with different pattern shapes are regularly connected. For example, the internal flow path 31 may have a configuration including a first flow path portion in which flow path elements 31x of pattern shape A are regularly connected and a second flow path portion connected to the downstream side of the first flow path portion and in which flow path elements 31x of pattern shape B are regularly connected.

[0029] Specifically, each internal flow path 31 has a shape that can be represented by a periodic function. More specifically, as shown in FIG. 2, the internal flow path 31 has a shape that can be represented by a Fourier series. Also, as shown in FIG. 3, the internal flow path 31 may have a fractal shape. The internal flow path 31 in FIG. 3 shows a shape that can be represented by a Gosper curve (here, it is two iterations, but it may be three or more iterations) which is a fractal shape. In addition, the internal flow path 31 may have a shape that can be represented by other fractal curves such as a Minkowski curve, a self-avoiding walk, a Koch curve, a Takagi curve, a dragon curve, a Hilbert curve, and a Weierstrass function.

[0030] <Simulation Results of Temperature Gradient> Next, the simulation results of the temperature gradient by the cooling plate forming the internal flow path of the present embodiment are shown in FIG. 4. Here, as a comparative example, (A) a case where the internal flow path is formed in a spiral shape is shown. Further, the internal flow path of the present embodiment has a shape that can be represented by (B) a Fourier series, which is a connection of flow path elements of the same pattern in a spiral shape, and (C) a shape that can be represented by a second-order Gosper curve. In these cases, the refrigerant is configured to be introduced from the central portion of the cooling plate and led out from the outer peripheral portion. Also, the refrigerant flowing through the internal flow path is laminar flow.

[0031] As can be seen from FIG. 4, when comparing the low-temperature region surrounded by the circle 21 and the high-temperature region near the circle 22, it can be seen that the temperature gradient is reduced in the configuration of the present embodiment compared to the comparative example. In the configuration of the present embodiment, since the flow path meanders in the direction from the inner side in the radial direction to the outer side in the radial direction (radial direction) of the cooling plate 3, the heat flux on the horizontal plane (particularly in the radial direction) of the cooling plate 3 can be promoted, and thereby the temperature gradient is reduced.

[0032] <Effect of the present embodiment> As described above, according to the electrostatic chuck device 100 in the present embodiment, since the internal flow path of the cooling plate has a flow path shape in which flow path elements of the same pattern are regularly connected in a plan view, it is possible to form a configuration in which the refrigerant flows while meandering between the inner side and the outer side in the radial direction of the cooling plate 3. As a result, the temperature difference between the inner side and the outer side in the radial direction and the temperature difference in the circumferential direction can be reduced, and the temperature gradient of the entire adsorption surface of the adsorption plate 2 can be made small. As a result, the temperature of the object adsorbed on the adsorption plate can be made uniform. Further, by adopting a flow path shape in which the flow path elements 31x of the same pattern are regularly connected, the design and processing become easier, and the mechanical strength of the cooling plate 3 can be increased.

[0033] <Other embodiments> For example, the metal forming the cooling plate is not limited to titanium. For example, 3D printing or additive manufacturing using alloy particles containing at least nickel (Ni), molybdenum (Mo), and chromium (Cr) such as Inconel (registered trademark) or metal particles containing aluminum (Al) may be used to form the cooling plate.

[0034] Furthermore, the electrostatic chuck device according to the present invention is not limited to applications such as plasma processing. The electrostatic chuck device according to the present invention may be used in other semiconductor manufacturing processes performed in a chamber.

[0035] In addition, various modifications and combinations of embodiments may be made as long as they do not depart from the spirit of the present invention.

Description of Reference Numerals

[0036] 100 ··· Electrostatic chuck device W ··· Object 2 ··· Adsorption plate 3 ··· Cooling plate 31 ··· Internal flow path 31x ··· Flow path element

Claims

1. An electrostatic chuck device that adsorbs an object by electrostatic force, comprising an adsorption plate having an adsorption surface for adsorbing the object on the surface side, and a cooling plate provided on the back surface side of the adsorption plate and having an internal flow path through which a refrigerant flows. The internal flow path has a flow path shape in which flow path elements of the same pattern are regularly connected in a plan view, the electrostatic chuck device.

2. The internal flow path communicates with a refrigerant introduction port and a refrigerant discharge port of the cooling plate, and the radial distance from the central portion of the cooling plate increases as it goes from the refrigerant introduction port to the refrigerant discharge port. The electrostatic chuck device according to claim 1, wherein the change and the change in the radial distance from the central portion are repeated.

3. The flow path element has a curved flow path portion, a bent flow path portion, or a flow path portion bent in the middle, the electrostatic chuck device according to claim 1 or 2.

4. The internal flow path has a meandering flow path shape by regularly connecting the flow path elements, the electrostatic chuck device according to claim 3.

5. The internal flow path has a shape that can be represented by a periodic function, the electrostatic chuck device according to claim 1.

6. The internal flow path has a shape that can be represented by a Fourier series, the electrostatic chuck device according to claim 1.

7. The internal flow path has a fractal shape, the electrostatic chuck device according to claim 1.

8. The internal flow path has a shape that can be represented by a Gosper curve or a Minkowski curve, the electrostatic chuck device according to claim 1.

9. A cooling plate used in an electrostatic chuck device that adsorbs an object by electrostatic force, having an internal flow path through which a refrigerant flows, wherein the internal flow path has a flow path shape in which flow path elements of the same pattern are regularly connected in a plan view, the cooling plate.

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