JP2020155598A - Electrostatic chuck - Google Patents

Abstract

To provide an electrostatic chuck capable of surely adsorbing a wrapping wafer in which a wrapping occurs without requiring a large scale mechanism.SOLUTION: An electrostatic chuck 1 is an electrostatic chuck 1 having a clamp surface 10 that clamps a semiconductor wafer with a clamp force by a clamp voltage applied to the electrostatic chuck 1, and the clamp surface 10 can be partially deviated in a vertical direction. The electrostatic chuck includes: a first clamp surface 11 which can be deviated to a vertical direction for enabling the partial deviation of the clamp surface 10 to a vertical direction; and a second clamp surface 12 distributed on an outside of the first clamp surface. The electrostatic chuck provides a vertical moving mechanism 20 for deviating the first clamp surface 11 and the second clamp surface 12 independently to the vertical direction, or forms the clamp surface 10 with an elastic deformable material to distribute the vertical moving mechanism 20 which can partially move the clamp surface 10 in vertical.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electrostatic chuck for clamping a semiconductor wafer, and is particularly suitable for gripping a warped wafer in which a warped wafer is generated when inspecting a semiconductor wafer in a chamber in a high vacuum state using an electron microscope. Electrostatic chuck.

With the recent advancement of information technology, semiconductor devices have come to be used in various devices around us. In addition, with the increasing performance and multifunctionality of semiconductor devices used, there is an increasing need to manage manufacturing processes by combining various inspections and measurements.

When manufacturing semiconductor devices such as semiconductor wafers, fine precision on the order of nanometers is required to manufacture semiconductor devices that can exhibit the required performance. Further, in order to inspect whether the manufactured semiconductor device can exhibit the required performance, a highly accurate and strict inspection method is required.

Such a strict inspection method cannot be established with a conventional optical microscope, and inspection using an electron microscope is required. In the inspection using an electron microscope, an inspection stage is installed in a vacuum chamber whose degree of vacuum is set to a high degree by a vacuum pump or the like, and the semiconductor device mounted on the inspection stage is inspected.

In such an inspection method that requires nanometer-order accuracy, how to accurately position the wafer on the inspection stage is an important issue.

As a technique for accurately gripping a wafer on an inspection stage, a technique described in Patent Document 1 has been proposed (Patent Document 1).

Special Table 2018-537002

The electrostatic chuck described in Patent Document 1 is composed of a single plate having sufficient rigidity and having substantially the same diameter as a wafer. According to the electrostatic chuck described in Patent Document 1, since the electrostatic chuck is composed of a single plate having no step, the wafer formed on the flat plate can be reliably gripped.

However, the wafer does not always maintain the ideal flat plate state, and various treatments are applied in the process process, and in some cases, a warp of about 0.5 to 1.0 mm may occur. As described above, there is a problem in holding the warped wafer in which the warp has occurred by using the electrostatic chuck.

In principle, the electrostatic chuck does not generate a sufficient suction force unless the wafer and the electrode are spaced apart from each other. In the warped wafer, an attractive force is generated at the portion that first contacts the electrostatic chuck, but the other portions float with respect to the chuck because they are along the warped wafer. Sufficient adsorption force is not generated in the floating portion, and it cannot be adsorbed even if it takes a sufficient time. Therefore, the flatness required for measurement cannot be obtained, and in the worst case, an accident such as dropping off may occur. Therefore, the development of an electrostatic chuck capable of reliably adsorbing a warped wafer in which warpage has occurred is an urgent issue.

The present invention has been made in view of such a demand, and an object of the present invention is to provide an electrostatic chuck that does not require a large-scale mechanism and can reliably adsorb a warped wafer in which warpage has occurred. To do.

The present invention provides the following solutions.

The invention according to the first feature is an electrostatic chuck having a clamping surface that clamps a semiconductor wafer by a clamping force due to a clamping voltage applied to the electrostatic chuck, and the clamping surface can be partially displaced in the vertical direction. There is an electrostatic chuck, which provides.

According to the invention according to the first feature, by using a clamping surface that can be partially displaced in the vertical direction, the front surface of the semiconductor wafer can be clamped even when the semiconductor wafer is warped. it can.

The invention according to the second feature is an invention according to the first feature, which is a first clamp surface that can be displaced in the vertical direction and a second clamp that is arranged outside the first clamp surface as clamp surfaces. Provided is an electrostatic chuck having a surface and having a vertical movement mechanism that independently displaces a first clamp surface and a second clamp surface in the vertical direction.

According to the invention according to the second feature, since the clamp surface has a first clamp surface that can be displaced in the vertical direction and a second clamp surface that is arranged outside the first clamp surface, the warped wafer. By independently displaced the first clamp surface and / or the second clamp surface in the upward or downward direction according to the shape, even if the warped wafer has a high warp on the inside, the warp on the outside is high. Even a wafer can be securely clamped.

The invention according to the third feature is an invention according to the first feature, wherein the clamp surface is formed of an elastically deformable material and a vertical movement mechanism for partially moving the clamp surface up and down is arranged. Provides an electric chuck.

According to the invention according to the third feature, since the clamp surface is formed of an elastically deformable material and a vertical movement mechanism for partially moving the clamp surface up and down is provided, the wafer does not have a complicated mechanism. It is possible to prepare a clamp surface having a shape that matches the warp of the surface.

According to the present invention, it is possible to provide an electrostatic chuck that does not require a large-scale mechanism and can reliably adsorb a warped wafer in which warpage has occurred.

FIG. 1A shows a plan view of the electrostatic chuck 1 according to the first embodiment, and FIG. 1B shows a front view of the electrostatic chuck 1 according to the first embodiment. FIG. 2 (a) is a schematic view when measuring a downwardly convex warped wafer using the electrostatic chuck 1 according to the first embodiment, and FIG. 2 (b) is an electrostatic diagram according to the first embodiment. A schematic diagram is shown when measuring an upwardly convex warped wafer using the chuck 1. FIG. 3A shows the first usage mode when the warped wafer is adsorbed by using the electrostatic chuck 1 according to the first embodiment, and FIG. 3B shows the static electricity according to the first embodiment. A second usage mode when sucking a warped wafer by using the chuck 1 is shown. FIG. 4A shows the first electrode pattern of the electrostatic chuck 1 according to the first embodiment, and FIG. 4B shows the second electrode pattern of the electrostatic chuck 1 according to the first embodiment. FIG. 5 shows a usage mode when the electrostatic chuck 1 according to the first embodiment is used as a substitute for the load / unload arm. FIG. 6A shows a front view of the electrostatic chuck 1 according to the second embodiment, and FIG. 6B shows a downwardly convex warped wafer using the electrostatic chuck 1 according to the second embodiment. FIG. 6C shows a schematic diagram when measuring an upwardly convex warped wafer using the electrostatic chuck 1 according to the second embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. It should be noted that this is only an example, and the technical scope of the present invention is not limited to this.

[Structure of electrostatic chuck 1 according to the first embodiment]
FIG. 1A is a plan view of the electrostatic chuck 1 according to the first embodiment, and FIG. 1B is a front view of the electrostatic chuck 1 according to the first embodiment. In FIGS. 1A and 1B, only the parts necessary for understanding the present invention are shown.

The electrostatic chuck 1 includes a clamp surface 10 for clamping a semiconductor wafer with a force corresponding to an applied clamping voltage, and a vertical movement mechanism 20 for displacing the clamp surface in the vertical direction.

In the present embodiment, the clamp surface 10 is formed of a highly rigid material such as ceramic or glass, and is configured to reliably adsorb the semiconductor wafer.

The clamp surface 10 in the present embodiment is disposed inside, and is disposed outside the first clamp surface 11 and the first clamp surface 11 which can be displaced in the vertical direction by the vertical movement mechanism 20 described later. It is composed of a clamp surface 12.

Further, the vertical movement mechanism 20 includes a first vertical movement mechanism 21 for moving the first clamp surface 11 up and down, and a second vertical movement mechanism 22 for moving the second clamp surface 12 up and down.

In this way, the first clamp surface 11 displaceable in the vertical direction, the second clamp surface 12 arranged outside the first clamp surface 11, and the first clamp surface 11 can be displaced in the vertical direction. By configuring the electrostatic chuck 1 with the mechanism 21 and the second vertical movement mechanism 22 that can displace the second clamp surface 12 in the vertical direction, the clamp surface located inside and the clamp surface located outside are independent. It can be partially displaced in the vertical direction, and wafers with warpage in various shapes can be attracted. For example, by fixing the second vertical movement mechanism 22 and driving the first vertical movement mechanism 21 upward, an upwardly convex clamp surface 10 can be formed.

[Example of using the electrostatic chuck 1 according to the first embodiment]
With reference to FIGS. 2 (a) and 2 (b), the operation of each part when sucking the warped wafer by using the electrostatic chuck 1 according to the first embodiment will be described. FIG. 2A is a schematic view when the electrostatic chuck 1 according to the first embodiment is used to adsorb a downwardly convex warped wafer, and FIG. 2B is an electrostatic diagram according to the first embodiment. A schematic diagram is shown when the chuck 1 is used to adsorb an upwardly convex warped wafer.

As shown in FIG. 2A, when the downwardly convex warped wafer is attracted, the first clamp arranged inside is used by the first vertical movement mechanism 21 that displaces the first clamp surface 11. The surface 11 is displaced downward. By doing so, it is possible to form a clamp surface having a high outside and a low inside to obtain a clamp surface that matches the shape of the warped wafer that is convex downward. As a result, the downwardly convex warped wafer can be reliably gripped.

Further, as shown in FIG. 2B, when the upwardly convex warped wafer is attracted, the first vertical movement mechanism 21 that displaces the first clamp surface 11 is used to dispose of the first vertically moving wafer 21 inside. (1) The clamp surface 11 is displaced upward. By doing so, it is possible to form a clamp surface having a high inside and a low outside to obtain a clamp surface that matches the shape of the warped wafer that is convex upward. As a result, the upwardly convex warped wafer can be reliably gripped.

In the examples shown in FIGS. 2 (a) and 2 (b), the second clamp surface 12 was fixed and only the first clamp surface 11 was displaced upward or downward, but this is not the only case. Instead, the first clamp surface 11 may be fixed and the second clamp surface 12 may be displaced so as to correspond to the shape of the warped wafer. Alternatively, both clamp surfaces may be displaced in the vertical direction.

Subsequently, with reference to FIGS. 3 (a) and 3 (b), a usage mode for inspecting after adsorbing the warped wafer using the electrostatic chuck 1 according to the first embodiment will be described.

In FIG. 3A, the warped wafer is attracted in a state of being aligned with the warp, and then the first clamp surface 11 and / or the second clamp surface 12 is displaced and deformed into the same plane. An example of performing an inspection such as exposure is shown.

In this example, in order to deform and correct the warped wafer, radial stress is applied to the wafer and the dimensions change.

As shown in FIG. 3A, when the wafer is exposed by an exposure apparatus, the wafer needs to be flat. Therefore, the warped wafer is formed by using the first vertical movement mechanism 21 and / or the second vertical movement mechanism 22. Straighten to a flat surface.

FIG. 3B shows an example in which a warped wafer is sucked in a state of being aligned with the warp and then inspected as it is. In such a case, no stress is applied to the wafer, and the wafer dimensions and the like can be measured in a natural state.

Subsequently, the electrode pattern of the electrostatic chuck 1 according to the first embodiment will be described with reference to FIGS. 4 (a) and 4 (b).

FIG. 4A is an example showing a pattern in which the respective clamp surfaces 11 and 12 are used as bipolar poles. In this example, two electrodes are connected to each of the clamp surfaces 11 and 12, and one clamp surface has both anode and cathode functions.

FIG. 4B is an example showing a pattern in which the respective clamp surfaces 11 and 12 are used as a single pole. In this example, one electrode is connected to each of the clamp surfaces 11 and 12, and one clamp surface has the function of either an anode or a cathode. At this time, when the first clamp surface 11 is used as the anode, the second clamp surface 12 becomes the cathode, and when the first clamp surface 11 is used as the cathode, the second clamp surface 12 becomes the anode.

Generally, when adsorbing a wafer, it is often used as a bipolar as shown in FIG. 4 (a), but when adsorbing a non-conductive material, a single pole as shown in FIG. 4 (b) is used. Sometimes.

Next, using FIGS. 5A to 5C, an example in which the electrostatic chuck 1 according to the first embodiment is provided with a part of the function of the load / unload arm to perform unloading. Will be described.

In the example shown in FIG. 5, the first clamp surface 11 is used for getting on and off the wafer. When lowering the wafer from the electrostatic chuck 1, first, as shown in FIG. 5A, the first clamp surface 11 is used to displace the wafer upward. Next, as shown in FIG. 5B, the load / unload arm 30 is moved below the wafer. In that state, as shown in FIG. 5C, when the first clamp surface 11 is lowered, the wafer is placed on the load / unload arm 30. Finally, the load / unload arm 30 moves the wafer to complete the unloading operation.

Similarly, in the loading work, the clamp surface 10 that can be displaced in the vertical direction can perform a part of the work of the load / unload arm 30. Further, in the example shown in FIG. 5, the first clamp surface 11 is used for getting on and off the wafer, but the present invention is not limited to this, and the second clamp surface 12 can be used for getting on and off the wafer.

[Structure of electrostatic chuck 1 according to the second embodiment]
When the configuration of the electrostatic chuck 1 according to the second embodiment and the electrostatic chuck 1 according to the second embodiment are used to attract the warped wafer by using FIGS. 6 (a) to 6 (c). The operation of each part of the above will be described. FIG. 6A shows a front view of the electrostatic chuck 1 according to the second embodiment, and FIG. 6B shows an upwardly convex warped wafer using the electrostatic chuck 1 according to the second embodiment. FIG. 6 (c) shows a schematic view when sucking a downwardly convex warped wafer by using the electrostatic chuck 1 according to the second embodiment.

The electrostatic chuck 1 according to the second embodiment is a vertical movement mechanism that partially displaces a single clamp surface 10 formed of a material having an elastic force such as a polyimide resin and the clamp surface 10 in the vertical direction. Has 20 and.

In the example shown in FIG. 6A, the vertical movement mechanism 20 includes a first vertical movement mechanism 21 provided at the center and a second vertical movement mechanism 22 provided at the ends, and by doing so, The clamp surface 10 can be partially displaced in the vertical direction. For example, by fixing the second vertical movement mechanism 22 and driving the first vertical movement mechanism 21 upward, an upwardly convex clamp surface 10 can be formed.

The vertical movement mechanism 20 to be arranged is not limited to the first vertical movement mechanism 21 and the second vertical movement mechanism 22, and may be provided in a place other than these places. Depending on the position and number of the vertical movement mechanisms 20, the suction operation can be performed according to the warp of various patterns of the wafer.

When the electrostatic chuck 1 according to the second embodiment is used to attract an upwardly convex warped wafer, as shown in FIG. 6B, a first vertical movement mechanism that displaces the clamp surface 10 near the center. 21 is used to drive the first vertical movement mechanism 21 upward to displace the clamp surface 10 near the center upward. By doing so, it is possible to form a clamp surface having a high inside and a low outside to obtain a clamp surface that matches the shape of the warped wafer that is convex upward. As a result, the upwardly convex warped wafer can be reliably gripped.

On the other hand, when the electrostatic chuck 1 according to the second embodiment is used to attract the downwardly convex warped wafer, as shown in FIG. 6C, the first upper and lower parts that displace the clamp surface 10 near the center. The moving mechanism 21 is used to drive the first vertical moving mechanism 21 downward to displace the clamp surface 10 near the center downward. By doing so, it is possible to form a clamp surface having a low inside and a high outside to obtain a clamp surface that matches the shape of the warped wafer that is convex downward. As a result, the downwardly convex warped wafer can be reliably gripped.

In the examples shown in FIGS. 6 (b) and 6 (c), the second vertical movement mechanism 22 was fixed and only the first vertical movement mechanism 21 was driven upward or downward, but this is limited to this. The first vertical movement mechanism 21 may be fixed and the second vertical movement mechanism 22 may be driven to deform the wafer so as to correspond to the shape of the warped wafer. Alternatively, both vertical movement mechanisms may be driven in the vertical direction.

As described above, by configuring the clamp surface to be partially displaceable in the vertical direction, an electrostatic chuck capable of reliably gripping warped wafers of various shapes without the need for a large-scale device. 1 can be provided.

Further, in the conventional electrostatic chuck, a lift pin for moving the semiconductor wafer mounted on the clamp surface up and down is required, but since it has a vertical movement mechanism for displacing in the vertical direction, the lift pin is not required. This makes it possible to provide an electrostatic chuck that can handle warped wafers while suppressing manufacturing costs and maintenance costs.

In the present invention, the electrostatic chuck that grips the semiconductor wafer on the inspection stage in the semiconductor inspection device has been described, but the present invention is not limited to the inspection device and is used for gripping the semiconductor wafer in various manufacturing processes. It can be done.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments described above. In addition, the effects described in the embodiments of the present invention merely list the most preferable effects arising from the present invention, and the effects according to the present invention are limited to those described in the embodiments of the present invention. is not.

1 Electrostatic chuck 10 Clamp surface 11 First clamp surface 12 Second clamp surface 20 Vertical movement mechanism 21 First vertical movement mechanism 22 Second vertical movement mechanism

Claims (3)

An electrostatic chuck having a clamping surface that clamps a semiconductor wafer by a clamping force due to a clamping voltage applied to the electrostatic chuck.
The clamp surface can be partially displaced in the vertical direction.
Electrostatic chuck. As a clamp surface, a first clamp surface that can be displaced in the vertical direction,
It has a second clamp surface disposed on the outside of the first clamp surface, and has a second clamp surface.
The electrostatic chuck according to claim 1, further comprising a vertical movement mechanism that independently displaces the first clamp surface and the second clamp surface in the vertical direction. The electrostatic chuck according to claim 1, wherein the clamp surface is formed of an elastically deformable material, and a vertical movement mechanism for partially moving the clamp surface up and down is provided.