JP2022169880A - Wafer support device - Google Patents

Abstract

To provide a wafer support device capable of reducing stress applied to a wafer in wafer processing performed at high temperatures.SOLUTION: A wafer support device P includes a wafer support device used during wafer processing at high temperature, a support base 2, at least one electrostatic attraction member E that attracts the wafer 1 in an area smaller than the outline of the wafer 1, a support member 4 that connects the support base 2 and the electrostatic attraction member E, and the support member 4 allows the electrostatic attraction member E to move following thermal deformation of the wafer 1 that occurs during wafer processing.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wafer support device for supporting wafers.

Some film deposition apparatuses, ion implantation apparatuses, and the like employ processes for processing wafers at high temperatures.
When the wafer is processed at a high temperature, stress due to thermal expansion is generated in the wafer, and the wafer is deformed into various shapes.

In order to suppress thermal deformation of the wafer, a method of firmly fixing the wafer using an electrostatic chuck is used during wafer processing. However, when such a fixing method is used, the suppressed stress applied to the wafer is released at once when the wafer is released from the electrostatic chuck. In that case, a problem occurs in which the wafer bounces off the electrostatic chuck when it is detached, and falls off. Therefore, a countermeasure against the wafer bouncing off the electrostatic chuck has been required.

As an example of countermeasures, Patent Document 1 proposes to release the wafer from the electrostatic chuck while pins are pressed against the upper surface of the wafer.

JP 2015-15330

Although the method of Patent Document 1 can prevent the wafer from jumping, depending on the magnitude of the stress applied to the wafer, the wafer may crack when it is released from the electrostatic chuck, or the wafer may be displaced in the radial direction. There is a concern that it may shift.

Therefore, a wafer supporting apparatus capable of reducing the stress applied to the wafer during wafer processing performed at high temperatures is provided.

The wafer support device
Wafer support equipment used for wafer processing at high temperatures,
a support base;
at least one electrostatic chucking member that chucks the wafer in an area smaller than the outline of the wafer;
a support member connecting the support base and the electrostatic adsorption member;
The support member allows the electrostatic attraction member to move following thermal deformation of the wafer that occurs during wafer processing.

By making the suction area of the wafer smaller than the outer shape of the wafer, it is possible to allow thermal deformation of the wafer at locations where the wafer is not supported by suction.
Moreover, by using a support member that allows the movement of the electrostatic attraction member following the thermal deformation of the wafer, it is possible to reduce the stress caused by suppressing the thermal deformation of the wafer.

Also, the wafer support device preferably has a protection member provided on the support base to protect the support member from charged particles used in wafer processing.

2. Description of the Related Art In a semiconductor processing process, wafer processing is performed using charged particles such as ion beams and plasma.
If the support member is visible to the charged particles used in wafer processing, the support member will be sputtered by the charged particles during wafer processing, causing problems such as unacceptable movement of the electrostatic attraction member. is concerned.
However, such concerns can be resolved by providing a protective member that protects the support member from charged particles.

When performing wafer processing with the support base tilted,
The electrostatic attraction member has a first electrostatic attraction member corresponding to the center of the wafer,
It is desirable to have a first movement restricting member that allows movement of the first electrostatic attraction member only in a direction perpendicular to the support base.

Since the movement direction of the first electrostatic attraction member is limited to the direction perpendicular to the support base by using the first movement restricting member, the wafer is prevented from sagging downward due to its own weight and colliding with the support base. be able to.

On the other hand, when performing wafer processing with the supporting base tilted,
The electrostatic attraction member has a second electrostatic attraction member corresponding to the outer circumference of the wafer,
allowing movement of the second electrostatic attraction member in a direction perpendicular to the support base, and allowing movement of the second electrostatic attraction member in a direction horizontal to the support base within a predetermined range; A configuration having a second movement restricting member may be employed.

The above configuration can also prevent the wafer from colliding with the support base.

By making the suction area of the wafer smaller than the outer shape of the wafer, thermal deformation of the wafer can be allowed at locations where the wafer is not supported by suction.
Moreover, by using a support member that allows the movement of the electrostatic attraction member following the thermal deformation of the wafer, it is possible to reduce the stress caused by suppressing the thermal deformation of the wafer.

FIG. 2 is a plan view showing a configuration example of a wafer support device; Cross-sectional view along line AA in FIG. Explanatory drawing of the movement of the electrostatic attraction member following the thermal deformation of the wafer. Explanatory drawing of protective material Explanatory diagram for tilt injection Explanatory drawing of the first movement restricting member Explanatory drawing of the second movement restricting member FIG. 3 is a plan view showing another configuration example of the wafer support device;

FIG. 1 is a plan view showing a configuration example of the wafer support device P. FIG. FIG. 2 is a cross-sectional view taken along line AA shown in FIG. A configuration example of the wafer support device P will be described with reference to FIGS. 1 and 2. FIG.

The wafer support device P is a wafer support device used when wafer processing is performed at a temperature higher than room temperature.
The wafer support device P has at least one electrostatic attraction member E. As shown in FIG. An attraction surface of an electrostatic chuck is provided on the surface of the electrostatic attraction member E that contacts the wafer 1, and the wafer is supported by attraction using this attraction surface.

For example, when four electrostatic attraction members are used, the electrostatic attraction members are distributed within the wafer surface. Specifically, as shown in FIG. 2, the wafer 1 is attracted using an electrostatic attraction member Ec that supports the center of the wafer 1 and three electrostatic attraction members E1 to E3 that support the outer periphery of the wafer 1. Support.

The total area of the electrostatic chuck regions of the electrostatic attraction members Ec, E1 to E3 is smaller than the area of the wafer 1. FIG. In other words, the electrostatic chucking member E chucks the wafer 1 in a region smaller than the outline of the wafer 1 . In other words, the wafer 1 has regions that are not supported by the electrostatic chuck.
Thermal deformation of the wafer is allowed in the unsupported region, so the stress applied to the wafer in this region is greatly reduced.

The wafer support device P has a support base 2 as a foundation. The electrostatic adsorption member E is supported by the support base 2 via the support member 4 .
The support member 4 is composed of, for example, a heat-resistant coil spring or leaf spring, and is configured to allow the movement even when the electrostatic attraction member E moves following the thermal deformation of the wafer 1. there is

By using the support member 4 described above, it is possible to reduce the stress caused by suppressing the thermal deformation of the wafer 1 . 1 and 2 and other drawings to be described later show the shape of the wafer before being thermally deformed. It transforms into various shapes such as potato chips.
As an example, FIG. 3 illustrates how the wafer is thermally deformed during wafer processing and the electrostatic adsorption members (Ec, E2, E3) move following this. Although not shown, the electrostatic attraction member E1 is arranged on the Y direction side of the electrostatic attraction member Ec in the figure, and the electrostatic attraction member E1 also moves following the thermal deformation of the wafer. .

2. Description of the Related Art In a semiconductor processing process, wafer processing is performed using charged particles such as ion beams and plasma.
If the support member 4 is visible to the charged particles used in wafer processing, the support member 4 may be sputtered by the charged particles during wafer processing, causing problems such as the movement of the electrostatic attraction member E becoming unacceptable. It is feared that

As a countermeasure for the above concerns, a wafer support device P shown in FIG. 4 may be adopted. In the configuration of FIG. 4, a protective member 7 is provided on the support base 2 to protect the outer periphery of the support member 4 of each electrostatic attraction member. The protection member 7 is, for example, a cylindrical member and accommodates the support member 4 therein.
Instead of the structure shown in FIG. 4, a structure may be adopted in which the protective member 7 is individually provided for the support member 4 of each electrostatic attraction member.

It is conceivable that the height of the protection member 7 from the support base 2 is set to a level that protects the sides of the support member 4 .
On the other hand, if wear of the electrostatic chucking member E is taken into account, the height of the protective member 7 from the support base 2 is partially adjusted in consideration of physical interference with the electrostatic chucking member E. It is conceivable that the electrostatic chucking member E should be protected.

As for the structure of the protection member 7, a plate-like member may be used to protect a part of the support member 4 other than the cylindrical member. In particular, if only a portion of the support member 4 is worn away by charged particles used in wafer processing, a configuration that partially protects the support member 4 may be adopted.

Wafer processing may be performed with the support base 2 tilted with respect to the direction of gravity G. FIG. FIG. 5 shows a state in which the tilt angle is set in the ion implantation process and the wafer is implanted with ions.
The ion beam IB is a ribbon beam elongated in the front and back direction of the paper surface, and the wafer supporting device P is scanned across the ion beam IB in the vertical direction of the drawing using a driving mechanism (not shown), thereby ions are directed onto the wafer 1. An injection process is being performed.

In the wafer processing of FIG. 5, since the support member 4 is a member that allows the movement of the electrostatic adsorption member E, there is concern that the wafer 1 may hang down from the support base 2 in the gravitational direction G due to its own weight. . The effect of gravity increases as the wafer surface and the direction of gravity G become parallel to each other in FIG. In other words, the greater the tilt angle of the support base 2 placed on the floor perpendicular to the direction of gravity G, the greater the effect of gravity. As a countermeasure for this concern, the configurations shown in FIGS. 6 and 7 may be employed.

In FIG. 6, a first movement restricting member 31 is used to restrict movement of the electrostatic attraction member Ec corresponding to the center of the wafer.
The first movement restricting member 31 restricts the moving direction of the electrostatic attraction member Ec to only the direction perpendicular to the support base 2 .

Specifically, the first movement restricting member 31 in FIG. 6A is a cylindrical member 3a having a diameter slightly larger than that of the electrostatic attraction member Ec. The cylindrical member 3a is supported by the support base 2, and the support member 4 and a portion of the electrostatic attraction member Ec are housed inside the cylindrical member 3a. This cylindrical member 3a may also serve as the protective member 7 described in FIG.

In the configuration using the cylindrical member 3a shown in FIG. 6A, since there is a slight gap between the first movement restricting member 31 and the electrostatic attraction member Ec, strictly speaking, the movement in directions other than the vertical direction is difficult. Movement will also take place. Specifically, it may move obliquely upward or downward, albeit with a slight movement. However, if the above-described gap is several percent with respect to the diameter of the electrostatic attraction member Ec, the components in the directions other than the vertical direction can be ignored. Therefore, the phrase "limited to the vertical direction" in the present invention also covers the case where the electrostatic attraction member Ec slightly moves in directions other than the vertical direction.
When the electrostatic attraction member Ec moves obliquely upward or downward, there is concern that the side surface of the electrostatic attraction member Ec may rub against the cylindrical member 3a and be worn. As a countermeasure, the configuration of FIG. 6B may be adopted.

The first movement restricting member 31 shown in FIG. 6B is formed with an annular protrusion 3b attached to the outer periphery of the electrostatic adsorption member Ec and a groove 3c for sliding the protrusion 3b in the vertical direction. and a plate member 3d.
The plate member 3d is curved along the annular protrusion 3b when viewed from above the support base 2, and is provided on the support base 2 on its left and right sides so as to sandwich the electrostatic attraction member Ec. ing.
By adopting the configuration shown in FIG. 6B, it is possible to prevent wear and tear associated with the movement of the electrostatic attraction member Ec.

A similar movement restricting member may be used for the electrostatic attraction members E1 to E3 corresponding to the outer periphery of the wafer.
FIG. 7 illustrates a configuration example in which a cylindrical second movement restricting member 32 is arranged around the outer periphery of the electrostatic adsorption members E1 to E3.
The second movement restricting member 32 has a larger diameter than the cylindrical member 3a exemplified as the first movement restricting member 31 in FIG. Not only the movement in the direction but also the movement in the horizontal direction of the support base 2 is allowed within a predetermined range.
The horizontal direction of the support base 2 is a direction parallel to the surface of the flat support base 2 . As for the actual movement of the electrostatic adsorption members E1 to E3, horizontal and vertical movements occur at the same time, and they sometimes move obliquely.

The movement distance of the electrostatic adsorption members E1 to E3 in the horizontal direction is limited by the inner diameter of the cylinder. As a result, although the horizontal movement of the electrostatic attraction members E1 to E3 is allowed within a predetermined range, the movement is restricted when the allowable range is exceeded. For this reason, the electrostatic attraction members E1 to E3 are not inclined beyond a certain degree. The predetermined range described above is determined based on the inclination angles of the electrostatic attraction members E1 to E3. This tilt angle is an angle that can prevent the wafer from tilting due to its own weight, and is changed according to the number and arrangement of the electrostatic attraction members.
In the horizontal direction, the movement of the electrostatic attraction members E1 to E3 due to thermal deformation of the wafer 1 is permitted to some extent, thereby reducing the occurrence of stress and preventing the wafer from tilting due to its own weight.

FIG. 8 shows a configuration example of a wafer supporting device P having a function of heating the wafer 1. As shown in FIG. The difference from the configurations described in the previous embodiments is that a heater 5 and a coolant channel 6 are provided.

The heater 5 is, for example, a disc-shaped PG heater or PBN heater, and is supported by the first movement restricting member 31 and the second movement restricting member 32 described with reference to FIGS. The heater 5 is used to heat the back side of the wafer 1 .
Note that the heater 5 may be supported by the support base 2 .

A reflector may be attached to the support base 2 in order to reflect the heat radiated from the heater 5 to the support base 2 side to the wafer 1 side. Also, for the same purpose, a reflective film may be attached to the surface of the support base 2 .

When the heater 5 is provided, there is concern that the set temperature of the heater 5 is high and exceeds the heat resistance temperature of the spring used for the support member 4 .
As a countermeasure against this, the support base 2 is provided with a coolant channel 6 to cool the support member 4 .
Instead of forming the cooling medium flow path 6 in the support base 2 , a piezoelectric element may be attached to the support member 4 or the support base 2 to cool the support member 4 .

In the above embodiment, the configuration for supporting the wafer using four electrostatic attraction members has been described, but the wafer 1 may be supported using only the electrostatic attraction member Ec corresponding to the center of the wafer.
As the number of electrostatic attraction members decreases, the area where the wafer 1 is not supported increases, so thermal deformation of the wafer during processing can be allowed accordingly.
Conversely, if the wafer 1 is stably supported, the number of electrostatic attraction members E may be increased to support the wafer at multiple points. For example, in that case, the electrostatic attraction member Ec corresponding to the center of the wafer may be eliminated, and the wafer 1 may be supported by three electrostatic attraction members E1 to E3 corresponding to the periphery of the wafer.

In addition, it goes without saying that the present invention is not limited to the above-described embodiments, and that various modifications are possible without departing from the spirit of the present invention.

P Wafer support device E, Ec, E1, E2, E3 Electrostatic adsorption member 2 Support base 4 Support member 7 Protective member 31 First movement limiting member 32 Second movement limiting member

Claims (4)

Wafer support equipment used for wafer processing at high temperatures,
a support base;
at least one electrostatic chucking member that chucks the wafer in an area smaller than the outline of the wafer;
a support member connecting the support base and the electrostatic adsorption member;
A wafer support device in which the support member allows movement of the electrostatic attraction member following thermal deformation of the wafer that occurs during wafer processing. 2. A wafer support apparatus according to claim 1, further comprising a protection member provided on said support base for protecting said support member from charged particles used in wafer processing. The electrostatic attraction member has a first electrostatic attraction member corresponding to the center of the wafer,
3. A wafer support apparatus according to claim 1, further comprising a first movement restricting member that permits movement of said first electrostatic attraction member only in a direction perpendicular to said support base. The electrostatic attraction member has a second electrostatic attraction member corresponding to the outer circumference of the wafer,
allowing movement of the second electrostatic attraction member in a direction perpendicular to the support base, and allowing movement of the second electrostatic attraction member in a direction horizontal to the support base within a predetermined range; 4. A wafer support apparatus according to any one of claims 1 to 3, further comprising a second movement restricting member.

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