JP5316172B2 - Wafer suction pad and pre-aligner having the same - Google Patents

Description

  The present invention relates to a pre-aligner that is used in a semiconductor manufacturing apparatus or inspection apparatus and performs angle alignment such as wafer centering and notching, and more particularly to a pad that sucks and holds a wafer.

A semiconductor wafer is provided with a notch or an orientation flat (orientation flat) serving as a mark in the crystal direction on the outer periphery thereof. In the semiconductor wafer processing process, there is a process in which processing is performed after matching the positions of the wafers, and the pre-aligner is a device that aligns the notch or orientation flat at a predetermined position.
In general, a pre-aligner is located in a semiconductor manufacturing apparatus or semiconductor inspection apparatus, is installed near a wafer handling robot, functions as a part of a semiconductor transfer system, and aligns the position of a wafer placed by the wafer handling robot. . The pre-aligner has a notch detection sensor for detecting the notch of the placed wafer. When the wafer is placed on the pad, the wafer outer periphery is sequentially sensed by the notch detection sensor by rotating the wafer. While detecting a notch position, a calculation process is performed from the turning position information at that time, and the notch position is turned to a predetermined position. Accordingly, since the pad on which the wafer is placed turns for detection and alignment of the notch position, it is necessary to securely hold and fix the wafer.

  Since the pre-aligner sequentially aligns the wafers one by one in this way, the operation time determines the throughput indicating the wafer processing capacity per unit time of the semiconductor manufacturing apparatus. Therefore, the pre-aligner is required to operate at high speed. Furthermore, since fine electronic circuits are formed on a semiconductor wafer, high accuracy is required for wafer alignment in the semiconductor wafer process. In addition, in order to form a fine electronic circuit, it is necessary to avoid adhesion of particles, which are extremely small dust and foreign matter, to the wafer. With the recent further miniaturization, not only the wafer surface but also the back surface There is a demand for particle reduction because the particles have an effect on miniaturization, and the pre-aligner also has a high demand for particle reduction particularly in a pad that is a part holding a wafer.

As a method of holding a wafer in a conventional semiconductor manufacturing apparatus, there is a method of holding a wafer by decompressing the back side of the wafer supported by a plurality of pin-shaped members with a fan (see, for example, Patent Document 1). ).
Further, as a method for holding the glass substrate, there is a method in which the inside of a seal ring made of rubber arranged concentrically is sucked with a vacuum pump and vacuum chucked (for example, see Patent Document 2).

JP-A-6-37082

JP-A-6-61134

In Patent Document 1, a negative pressure is generated while sucking an open space with a fan. However, since the fan is a fan, it takes time to obtain a holding force. In addition, since it is a fan, it takes time to release the holding force, and there is a problem that the responsiveness is poor. For this reason, the throughput cannot be improved, and there is a problem that it cannot be applied to an apparatus that requires the throughput.
Further, in Patent Document 1, a case where a vacuum pump is connected instead of a fan is considered as a method for obtaining a negative pressure due to the problem of responsiveness. In this case, since the ratio of the atmospheric part to the wafer peripheral portion is large, the volume of vacuum suction is extremely large, that is, the open space is sucked, so that sufficient holding force is obtained without increasing the degree of vacuum. Cannot be used, or it takes time to obtain a holding force, the vacuum level of a vacuum source such as a vacuum pump is lowered, and if other vacuum equipment is used, the effect on them will be affected. There are many problems, such as the need for a large capacity vacuum pump to reduce these effects.

In Patent Document 2, an inner seal ring and an outer seal ring are provided, and vacuum suction is performed on the inner side, and the portion surrounded by the seal ring is in a sealed state. However, since it is a continuous annular seal ring, there are many contact portions on the back surface of the wafer, and there is a problem that there is much particle contamination on the back surface of the wafer. This is because the contact portion of the wafer is inevitably contaminated by the transfer of particles through the seal ring. Therefore, if the contact portion is large, the back surface of the wafer is contaminated.
Further, when the wafer is held, airtightness between the wafer back surface is maintained by the seal ring. For this reason, when the wafer is delivered to the wafer transfer robot or the like and the atmosphere is introduced to release the holding force, there is a problem that the position of the wafer is shifted due to the momentum of the atmosphere. If the aligned wafer is displaced, there is a problem that the positional accuracy cannot be maintained, and as a result, the alignment accuracy of the pre-aligner is deteriorated. In order to minimize this problem, when a method of gradually flowing the air inflow rate such as a slow vent is taken, there is a problem that it takes time until the holding force is released and the throughput is deteriorated.

The present invention has been made in view of the above, and is suitable for an apparatus in which the throughput of the apparatus is required and the positional accuracy of the wafer on the pad is required even after the wafer holding unit is opened. An object of the present invention is to provide a pre-aligner that has very high throughput and alignment accuracy and is extremely low in particle contamination.

In order to solve the above problem, the present invention is configured as follows.
The present invention provides a wafer suction pad for vacuum-sucking and holding a wafer to directly support the wafer by protruding from the surface of the pad and to form a plurality of gaps between the surface of the pad and the wafer. A support piece, a first vacuum groove formed inside the plurality of support pieces and forming a substantially closed space together with the wafer, and formed outside the plurality of support pieces and forming a substantially closed space together with the wafer. A second vacuum groove, and the relationship between the pressure G1 in the substantially closed space of the first vacuum groove and the pressure G2 in the substantially closed space of the second vacuum groove satisfies G1 ≦ G2. The wafer suction pad is characterized in that the two vacuum grooves are vacuum-sucked.
Further, the present invention each of the plurality of supporting pieces, characterized in that it is made of rubber.
Further, in the present invention, the plurality of support pieces are arranged on the same circumference, the first vacuum groove is formed so as to draw a circle concentric with the circumference, and the circumference of the plurality of support pieces and the It said second vacuum groove to draw a circle of a circle concentric to the first vacuum groove is formed, characterized in that it is formed in an annular shape.
Further, the present invention is characterized in that a vacuum source for vacuum suction of the first vacuum groove, a vacuum source for vacuum suction of the second vacuum groove is provided each independently.
In the present invention, the vacuum source for vacuum suction of the first vacuum groove and the vacuum source for vacuum suction of the second vacuum groove are the same, and the flow path for vacuum suction of the second vacuum groove vacuum suction of the second vacuum groove, characterized in that the weakened than vacuum suction of the first vacuum groove by a regulator provided.
Further, the present invention includes a pad for holding the wafer by vacuum suction, a turning mechanism for turning the pad holding the wafer, and a sensor for detecting the outer periphery of the wafer held by the pad. In the pre-aligner for rotating the detected notch or orientation flat of the wafer in a desired direction, the pad protrudes from the surface of the pad and directly supports the wafer, and a minute amount is provided between the surface of the pad and the wafer. A plurality of support pieces that form gaps, a first vacuum groove that is formed inside the plurality of support pieces and forms a substantially closed space together with the wafer, and that is formed outside the plurality of support pieces, together with the wafer A second vacuum groove that forms a substantially closed space, and a relationship between a pressure G1 of the substantially closed space of the first vacuum groove and a pressure G2 of the substantially closed space of the second vacuum groove. But, G1 ≦ G2 become such that the first and second vacuum grooves in which the pre-aligner that characterized in that it is vacuum.
Further, the present invention is a semiconductor conveyance system characterized by comprising said realigner, and a wafer handling robot for placing the wafer on the pre-aligner.
Further, the present invention is a semiconductor manufacturing apparatus characterized by comprising said semiconductor transfer system.
The present invention also provides a semiconductor inspection apparatus comprising the semiconductor transfer system.

According to the present invention, since there are two vacuum grooves, a sufficient degree of vacuum can be ensured and the holding force of the wafer can be obtained, and the response time when the holding force is applied and when it is released is also high. It can be shortened and high throughput can be achieved.
In addition, since the wafer and the vacuum groove are in a substantially closed space when the holding force is released, since the vacuum groove returns to atmospheric pressure without affecting the position of the wafer, the wafer does not shift. High precision alignment is possible. Further, only the support piece is in contact with the wafer back surface, and there is almost no area of the wafer contact portion, so that there is very little particle adhesion on the wafer back surface.
Therefore, according to the present invention, it is possible to provide a pre-aligner with extremely low particle contamination while having high throughput and high alignment accuracy.

Side sectional view of the pre-aligner of the present invention The top view and side sectional view which expanded the pad part of the pre-aligner of FIG. Side sectional view of a pre-aligner showing another embodiment in the flow path formation of the pre-aligner of the present invention The top view and side sectional view showing other examples in the pad of the pre-aligner of the present invention

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

The configuration of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view of a pre-aligner of the present invention, and FIG. 2 is an enlarged top view and side sectional view of only the pad portion.
Reference numeral 1 denotes a pad on which a wafer is placed, and is fixed to the pad base 2. Bearings are provided on the outer periphery of the pad base 2, and the pad base 2 and the pad 1 are supported rotatably with respect to the apparatus main body. A rotary joint 4 is connected to the lower side of the pad base 2. The rotary joint 4 is composed of two parts divided into upper and lower parts, and a plurality of independent passages through which compressed air or vacuum can flow are formed, and either one of the upper and lower parts can turn continuously. In this embodiment, the upper side is turned. In addition, since the flow path is sealed independently even during turning, the pressure of the gas in the flow path does not change at all.
Further, the pad base 2 is provided with a pulley 5, and is connected to a pulley 6 provided at a shaft end of a turning motor 8 serving as a servo motor by a timing belt 7, and the pad base 2 performs a turning operation. The turning position information is managed by a controller (not shown).
A notch detection sensor 9 is provided near the outer periphery of the wafer placed on the pad 1 and can detect the notch position of the wafer. By turning the wafer placed on the pad 1, the notch detection sensor 9 senses a notch on the outer periphery of the wafer, and the notch position information and the turning position information are arithmetically processed by a controller (not shown). The notch can be indexed and the wafer can be swung to a predetermined position.

On the upper surface of the pad 1, four convex wafer support pieces 10 made of rubber protruding only slightly from the pad surface are arranged on the circumference, and a circular shape is formed inside the support piece 10 on the pad 1. The first vacuum groove 11 is formed, and on the other hand, an annular second vacuum groove 12 is formed on the outer side of the support piece 10 concentrically with the first vacuum groove 11. Therefore, since the wafer is supported by the wafer support piece 10, it does not contact the upper surface of the pad 1 itself, and a minute gap is generated between the upper surface of the pad 1 and the lower surface of the wafer.
The first vacuum groove 11 and the second vacuum groove 12 are each connected to a flow path formed independently inside the pad base 2, and further communicated with the flow path of the rotary joint 4. The flow path communicating from the lower part serving as the fixed side of the rotary joint 4 to the first vacuum groove 11 is connected to the vacuum source of the semiconductor manufacturing apparatus via the solenoid valve 13 for switching to the atmospheric flow path. Has been. On the other hand, the flow path communicating with the second vacuum groove 12 is connected to a vacuum generation unit 14 including a vacuum generator for generating a vacuum from compressed air or the like, a solenoid valve for switching to the atmospheric flow path, and the like. .

FIG. 3 shows another embodiment of the formation of the flow path of the present invention. The vacuum regulator 15 is connected to the flow path communicating with the second vacuum groove 12 and then communicated with the first vacuum groove 11. It can be applied when the vacuum generating capacity and capacity of the connected vacuum source are sufficiently large.

FIG. 4 shows another embodiment of the pad, in which the wafer support piece 10 from the pad surface is embedded and fixed so that a cut piece of an O-ring made of rubber protrudes only slightly.

Next, the operation of the pre-aligner of the present invention will be described.
A wafer handling robot (not shown) places the wafer on the pad 1 of the pre-aligner. When placed, vacuum suction is performed on the first vacuum groove 11 and the second vacuum groove 12 by the solenoid valve 13 and the vacuum generation unit 14. In addition to the frictional force caused by the wafer support piece 10, the holding force by vacuum suction increases and the wafer is held by the pad 1. Next, a wafer turning operation is performed to detect the notch position.
At the time of this vacuum suction, the first vacuum groove 11 evacuates the vacuum in the substantially closed space formed by the first vacuum groove 11 without a heavy burden on the vacuum source because the differential pressure is small due to the second vacuum groove 12 on the outer periphery. Can be secured. In addition, since the second vacuum groove 12 is the atmosphere outside the substantially closed space formed by the second vacuum groove 12, it is not easy to suck up to a high degree of vacuum in terms of securing the degree of vacuum in this space. Since it is independent of the vacuum source of the first vacuum groove 11, there is no influence on ensuring a high degree of vacuum required for the first vacuum groove 11.
When the capacity of the vacuum source of the first vacuum groove 11 is sufficiently large, the vacuum regulator 15 may be adjusted so that a high degree of vacuum can be secured in the first vacuum groove 11 as shown in the example of FIG.

Since the present invention has such a configuration, the holding force can be immediately increased by vacuum suction, and the wafer turning operation for detecting the notch position can be immediately performed.
Then, the wafer is further swiveled so that the notch position becomes a predetermined position by the notch detection by the notch detection sensor 9 and the turning position information at that time by a calculation process by a controller (not shown), and alignment is performed. End the operation.

Thereafter, when a wafer handling robot (not shown) accesses the pad 1 of the pre-aligner, the solenoid valve 13. By switching the vacuum generation unit 14, the vacuum application is released and the wafer is removed. Regarding the opening of the vacuum suction, the first vacuum groove 11 and the second vacuum groove 12 are substantially closed spaces with a slight gap between the support piece 10 and the lower surface of the wafer. The vacuum suction can be released immediately without shifting and without taking time.

As described above, according to the present invention, since there are two vacuum grooves, a sufficient holding force can be obtained, and since the responsiveness at the time of applying and releasing the holding force is high, the alignment time can be shortened. it can. In addition, since the wafer is not displaced even when the holding force is released, highly accurate alignment can be performed. Furthermore, since only the wafer support piece is in contact with the wafer back surface and there is almost no area of the wafer contact portion, it is possible to provide a pre-aligner with very little particle adhesion on the wafer back surface.

DESCRIPTION OF SYMBOLS 1 Pad 2 Pad base 3 Bearing 4 Rotary joint 5 Pulley 6 Pulley 7 Timing belt 8 Turning motor 9 Notch detection sensor 10 Wafer support piece 11 1st vacuum groove 12 2nd vacuum groove 13 Solenoid valve 14 Vacuum generation unit 15 Vacuum regulator

Claims (9)

In the wafer suction pad that holds the wafer by vacuum suction,
A plurality of support pieces that protrude from the surface of the pad and directly support the wafer, and form minute gaps between the surface and the wafer over the entire surface of the pad;
A first vacuum groove formed inside the plurality of support pieces and forming a substantially closed space together with the wafer;
A second vacuum groove formed outside the plurality of support pieces and forming a substantially closed space together with the wafer,
The first and second vacuum grooves are vacuum-sucked so that the relationship between the pressure G1 in the substantially closed space of the first vacuum groove and the pressure G2 in the substantially closed space of the second vacuum groove satisfies G1 ≦ G2. A wafer suction pad characterized by that.   The wafer suction pad according to claim 1, wherein each of the plurality of support pieces is made of rubber.   The plurality of support pieces are arranged on the same circumference, the first vacuum groove is formed so as to draw a circle concentric with the circumference, and the circumference of the plurality of support pieces and the first vacuum groove are formed. 2. The wafer suction pad according to claim 1, wherein the second vacuum groove is formed in an annular shape so as to draw a circle concentric with the circle to be formed.   2. The wafer suction pad according to claim 1, wherein a vacuum source for vacuum suction of the first vacuum groove and a vacuum source for vacuum suction of the second vacuum groove are provided independently.   The vacuum source for vacuum suction of the first vacuum groove and the vacuum source for vacuum suction of the second vacuum groove are the same, and a regulator provided in the flow path for vacuum suction of the second vacuum groove 2. The wafer suction pad according to claim 1, wherein the vacuum suction of the second vacuum groove is weaker than the vacuum suction of the first vacuum groove. A pad for holding the wafer by vacuum suction, a turning mechanism for turning the pad holding the wafer, and a sensor for detecting an outer periphery of the wafer held by the pad, and the wafer detected by the sensor. In the pre-aligner that rotates the notch or orientation flat in the desired direction,
The pad is
A plurality of support pieces that protrude from the surface of the pad and directly support the wafer, and form minute gaps between the surface and the wafer over the entire surface of the pad;
A first vacuum groove formed inside the plurality of support pieces and forming a substantially closed space together with the wafer;
A second vacuum groove formed outside the plurality of support pieces and forming a substantially closed space together with the wafer,
The first and second vacuum grooves are vacuum-sucked so that the relationship between the pressure G1 in the substantially closed space of the first vacuum groove and the pressure G2 in the substantially closed space of the second vacuum groove satisfies G1 ≦ G2. Pre-aligner characterized by that.   7. A semiconductor transfer system comprising: the pre-aligner according to claim 6; and a wafer handling robot for placing the wafer on the pre-aligner.   A semiconductor manufacturing apparatus comprising the semiconductor transfer system according to claim 7.   A semiconductor inspection apparatus comprising the semiconductor transfer system according to claim 7.

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