JP7430872B2 - Conveyance method and conveyance device - Google Patents

Description

The present invention relates to a transport method and a transport apparatus for transporting a wafer to a hole in a carrier arranged between upper and lower surface plates of a double-sided polishing apparatus.

Conventionally, as an apparatus for polishing both sides of a wafer such as a semiconductor substrate, a carrier having a plurality of circular holes is meshed with a sun gear and an internal gear, and the wafer is inserted into the hole. The wafer is held in such a way that both sides of the wafer are sandwiched between an upper surface plate and a lower surface plate, and the carrier is moved in a planetary gear by a sun gear, etc., and at the same time, the upper and lower surfaces are rotated in relative directions. Devices that simultaneously polish both are known. As a technique for transporting and loading a wafer into a hole of such a carrier, a method and apparatus as disclosed in Patent Document 1, for example, are known.

In Patent Document 1, a visual sensor such as a camera or CCD optically recognizes the workpiece holding surface of a carrier, outputs image recognition data, processes the image recognition data, and identifies a reference mark on the workpiece holding surface of the carrier. The position of the carrier hole is determined based on this. Then, the robot arm for transporting the workpiece is controlled based on the determined hole position.
In this way, in the past, holes in the carrier were captured as image data using a camera, and wafers were transported based on this data.

However, when using a camera image to transport a wafer into a hole of a carrier, a camera and a computer for image processing are required, resulting in an expensive and space-consuming device. Therefore, it was difficult to install it for all double-sided polishing machines.

Japanese Patent Application Publication No. 11-207611

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a transfer method and a transfer device that can inexpensively transfer a wafer to a hole in a carrier in a wafer processing device such as a double-sided polishing device. shall be.

In order to achieve the above object, the present invention provides a transport method for transporting a wafer to a hole in a carrier disposed between upper and lower surface plates of a wafer processing apparatus, comprising:
passing a transfer head holding the wafer over the carrier by rotating a rotatable arm to which the transfer head is attached;
When passing over the carrier, a displacement sensor disposed on the transport head detects the inner peripheral edge of the hole from the transport head side based on the height difference between the surface of the carrier and the hole;
A control means for controlling the position of the arm calculates the center position of the hole from the position data of the displacement sensor when the inner peripheral edge of the hole is detected, and based on the calculated center position of the hole, the wafer is There is provided a transport method characterized in that the wafer is transported into a hole of the carrier by controlling the position of the transport head holding the wafer via the arm.

With the transport method of the present invention, carrier holes can be compactly, easily, and inexpensively used by displacement sensors without the need for expensive and space-consuming equipment such as visual sensors such as cameras or image processing computers. By calculating the center position of the wafer, it is possible to accurately transport the wafer into the hole without misalignment.

At this time, the displacement sensor can be a laser sensor.

Laser sensors are often used as displacement sensors and can be easily prepared.

At this time, the four displacement sensors are arranged at equal intervals along the outer periphery of the transport head,
a step A of selecting a combination of three position data from among four position data of the displacement sensor when detecting the inner peripheral edge of the hole;
Step B of configuring a triangle consisting of two short sides and one hypotenuse from the combination of the three selected position data;
step C of obtaining the intersection of the perpendicular bisectors of each of the two short sides as a candidate for the center position of the hole;
Step D of obtaining one or more different candidates for the center position of the hole by selecting three combinations of position data different from those selected in Step A and repeating Steps B and C;
The center position of the hole can be calculated from the average of all candidates for the center position of the hole obtained in steps A to D.

In this way, the center position of the hole in the carrier can be calculated more accurately, and the wafer can be transported into the hole more reliably.

The present invention also provides a transport device for transporting a wafer to a hole in a carrier disposed between upper and lower surface plates of a wafer processing device, comprising:
It has a transfer head that holds the wafer, a rotatable arm to which the transfer head is attached, and a control means that controls the position of the arm,
A displacement sensor is disposed on the transfer head,
The displacement sensor is capable of detecting the inner peripheral edge of the hole based on the height difference between the surface of the carrier and the hole from the side of the transfer head passing over the carrier by the arm,
The control means calculates the center position of the hole from position data of the displacement sensor when detecting the inner peripheral edge of the hole, and controls the transfer head that holds the wafer based on the calculated center position of the hole. Provided is a conveying device characterized in that the position of the conveyor can be controlled via the arm.

With the conveyance device of the present invention, the displace- ment sensor installed allows the carrier to be compactly, easily, and inexpensively handled without the need for expensive and space-consuming equipment such as a visual sensor such as a camera or an image processing computer. The central position of the hole can be calculated, and furthermore, the wafer carrier can be accurately transported into the hole.

At this time, the displacement sensor may be a laser sensor.

Laser sensors are often used as displacement sensors and can be easily prepared.

At this time, the four displacement sensors may be arranged at equal intervals along the outer periphery of the transport head.

With such a device, the center position of the hole in the carrier can be calculated more accurately, and the wafer can be transported into the hole more reliably.

As described above, the transport method and transport apparatus of the present invention do not require the relatively expensive and space-consuming visual sensor and image processing computer that were used when transporting the wafer carrier to the hall. By using a displacement sensor, the center position of the hole in the carrier can be calculated in a compact, simple, and inexpensive manner, and the wafer can be accurately transported and loaded into the hole without shifting.

1 is a schematic diagram showing an example of a conveyance device of the present invention. It is a schematic diagram showing an example of a conveyance head and an arm. FIG. 3 is an explanatory diagram showing an example of detection of the inner peripheral edge of a hole by a displacement sensor. FIG. 2 is a longitudinal cross-sectional view showing an example of a double-sided polishing device. FIG. 6 is an explanatory diagram showing an example of detection of the inner peripheral edge of a hole by a displacement sensor in a plan view. (1) The state at the start of detection, and (2) the state after the end of detection. FIG. 6 is an explanatory diagram of a process of calculating the center position of a hole from position data of a displacement sensor. (1) Steps A to C are shown, and (2) Step D and the average calculation step are shown.

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 shows an example of a conveying device according to the present invention. Note that a double-sided polishing device is also illustrated. Although a double-sided polishing device will be described as an example of a wafer processing device, a double-sided lapping device having almost the same mechanism may also be used.
The conveying device 1 of the present invention can perform processing without requiring an expensive camera or image processing computer as in the past, compared to a double-sided polishing device 2 that polishes both sides of a wafer such as a silicon wafer as a semiconductor substrate. This is an inexpensive and space-saving device that can be accurately loaded and set into a circular hole in a carrier that holds a wafer.

First, a double-sided polishing apparatus 2 to which the conveying apparatus of the present invention can be applied will be described. FIG. 4 shows an example of a longitudinal cross-sectional view of a double-sided polishing apparatus. As shown in FIG. 4, the carrier C is placed between the upper surface plate UT and the lower surface plate LT. The carrier C is equipped with a sun gear SG and an internal gear IG for planetary gear movement, and the outer circumference of the carrier C is provided with external teeth for meshing with the sun gear SG and internal gear IG. A circular hole H into which the wafer W is inserted and held is provided inside the carrier C.
Note that the inner peripheral edge of the hole H of the carrier C may be made of the carrier base material itself, or may be made of an insert made of resin or the like arranged in the carrier base material. Furthermore, polishing cloths PP for polishing the wafer W are attached to the surfaces of the upper and lower surface plates UT and LT that face each other.
As described above, the double-side polishing apparatus 2 itself equipped with the carrier C can be the same as the conventional one, for example.

When polishing both sides, after transporting the wafer W into the hole H of the carrier C, the horizontally swingable upper surface plate UT is swing-moved to move the wafer W between the lower surface plate LT and the upper surface plate UT. to hold. By rotating the sun gear SG, etc., the carrier C is moved in a planetary gear motion, and at the same time, the lower surface plate LT and the upper surface plate UT are rotated in the relative direction while supplying polishing liquid to the clamping surfaces, and both surfaces of the wafer W are placed on each surface plate. Polishing is performed using the polishing cloth PP on the side of the clamping surface.

In contrast to such a double-side polishing apparatus 2, a transfer apparatus 1 of the present invention for transferring a wafer to a hole H of a carrier C includes a transfer head 3 that holds a wafer W, and a transfer head 3 that is attached to the rotation. It has a movable arm 4 and control means 5 for controlling the position of the arm 4. Further, a displacement sensor 6 is disposed on the transport head 3.
Here, FIG. 2 shows an example of the transport head 3 and the arm 4.
The transfer head 3 is attached to the tip of the arm 4, and the transfer head 3 can be freely rotated. The rotation mechanism itself is not particularly limited, and may be the same as the conventional one, for example. The movements of the arm 4 and the transfer head 3 can be controlled by a control means 5. In particular, the position of the transfer head 3 can be adjusted via the arm 4 so that the wafer W taken out from the wafer cassette 7 can be transferred into the hole H of the carrier C.

Further, the structure of the transfer head 3 for holding the wafer W is not particularly limited, and may be the same as the conventional structure, for example. It is only necessary that the control means 5 be able to hold the wafer W taken out from the wafer cassette 7 by suction or the like, and to detach the wafer W above the hole H.

The displacement sensor 6 measures the distance between the displacement sensor 6 and an object, and is used to obtain the center position of the hole H of the carrier C placed on the lower surface plate LT (polishing cloth PP). It is. More specifically, the inner peripheral edge of the hole H can be detected from the transfer head 3 side passing over the carrier C using the arm 4 based on the height difference between the surface of the carrier C and the hole H.
The displacement sensor 6 can be, for example, a laser sensor. Laser sensors are small, easy to prepare, and relatively low cost. By irradiating a laser toward the surface of the carrier C, it is possible to measure the distance between the laser sensor and the object.

As the transport head 3 passes over the carrier C, when passing above the hole H, the distance from the displacement sensor 6 such as a laser sensor changes significantly compared to before. That is, when the carrier C is passing horizontally above the surface of the carrier C, the distance measured by the displacement sensor 6 is almost constant depending on the distance between the surface and the displacement sensor 6, but the distance measured by the displacement sensor 6 is almost constant. When the displacement sensor 6 reaches above the hole H, since the hole H is hollow, the object facing the displacement sensor 6 is the polishing cloth PP attached to the lower surface plate LT, and the polishing cloth PP is affixed to the lower surface plate LT. A change occurs in which the distance measured by the displacement sensor 6 becomes larger. Moreover, when the position of the displacement sensor 6 moves from above the hole H to above the surface of the carrier C, a change occurs in which the measurement distance becomes smaller by the thickness of the carrier C. Due to this measurement distance variation (height difference between the surface of carrier C and hole H), the boundary between the surface of carrier C and hole H, that is, the inner peripheral edge of hole H (also, the position of displacement sensor 6 located above it) data) can be detected.

Figure 3 shows how the inner edge of the hole is detected by the displacement sensor. In the example shown in FIG. 3, an insert I is disposed at the inner peripheral edge of the carrier C forming the hole H. In the example shown in FIG. In this case, there is a height difference because there is a step between the corner of the insert I, which is the inner peripheral edge of the hole H, and the hole H itself (ie, the cavity). While irradiating a laser toward the surface of the carrier C from a displacement sensor (laser sensor) 6 disposed on the outer periphery of the transfer head 3, the transfer head 3 is rotated by the arm 4 together with the displacement sensor 6, and the carrier C is rotated by the arm 4. When passing above, it can be seen that the measured distance changes greatly with the inner peripheral edge of the hole H as a boundary, as described above.

Furthermore, the number of displacement sensors 6 is not limited and can be determined as appropriate; for example, four displacement sensors 6 may be provided. Here, these four displacement sensors 6 are arranged on the outer periphery of the transport head 3 at equal intervals in a plan view. It is preferable to have four because the center position of the hole H of the carrier C can be calculated more accurately. The larger the number, the more positional data regarding the inner periphery of the hole H can be acquired, making it easier to more accurately calculate the center position of the hole H, but the number may be determined in consideration of cost.

Furthermore, the control means 5 can be, for example, a computer. The functions of this computer can be broadly divided into, for example, a control unit that controls the arm 4, etc., a data processing unit that processes signal data from the displacement sensor 6 to obtain position data, and a data processing unit that processes the signal data from the displacement sensor 6 to obtain position data. It consists of an arithmetic unit that calculates H. Naturally, it may have functions other than these. Furthermore, the upper and lower surface plates UT, LT, etc. of the double-sided polishing apparatus 2 may also be controllable.
The control unit can control the connected arm 4 to rotate as desired. In addition, the positional relationship between the arm 4 and the transfer head 3, as well as the positional relationship between the center of the transfer head 3 and the displacement sensor 6 disposed on the outer periphery thereof, can be obtained in advance and inputted. It is possible to obtain position data of the arm 4, the transfer head 3, and even the displacement sensor 6 from the rotational state of the arm 4, and also to control the position. For example, it is possible to set virtual XY coordinates on a horizontal plane where the fulcrum of the rotation of the arm 4 is X=0, Y=0, and the position of the displacement sensor 6 etc. can be converted into coordinates and obtained at the XY coordinates. , can be moved to the desired coordinate position.
In particular, the position of the transfer head 3 that holds the wafer W can be controlled via the arm 4 based on the center position of the hole H calculated by the calculation unit. Specifically, the arm 4 can be rotated so that the center of the transfer head 3 (the center of the held wafer W) coincides with the center position of the hole H.

Further, the data processing section of the control means 5 can receive a signal from the displacement sensor 6, and can acquire the transition of data on the distance measured by the displacement sensor 6. Then, from the above-mentioned fluctuation in the acquired measurement distance data, it is possible to know the timing at which the inner circumferential edge of the hole H of the carrier C was detected, and the position data of the displacement sensor 6 at that time (in other words, the position above the inner circumferential edge) can be known. The position data of the displacement sensor 6 or the position data of the inner circumferential edge) can be obtained from, for example, information from the control unit.
Furthermore, the calculation unit can calculate the center position of the hole H from the acquired position data. The calculation program itself is not particularly limited as long as it can calculate the center position of hole H. In the explanation of the conveyance method of the present invention to be described later, an example thereof will be explained in detail.

With the transport device of the present invention as described above, the center position of the hole H can be calculated, and the wafer W held by the transport head 3 can be accurately transported and loaded into the hole H. It is. A conventional device equipped with a visual sensor requires relatively expensive equipment and processing software such as an image processing computer in addition to the visual sensor, resulting in an overall expensive and space-consuming conveyance device. This may also lead to an increase in the cost of polished wafers W.
On the other hand, in the present invention, since the displacement sensor 6, which is relatively low cost, is provided, it is possible to provide an inexpensive and space-saving device. As a computer for data processing, it only needs to be able to process the data of the distance measured by the displacement sensor 6, so there is no need to process complex data such as images, and the processing software can be simple and inexpensive. can.

Next, a conveyance method of the present invention using the conveyance device 1 of the present invention shown in FIGS. 1-3 will be explained. Note that although a case will be described here in which a laser sensor is used as the displacement sensor 6 and four displacement sensors 6 are arranged at equal intervals around the outer circumference of the transport head 3, the present invention is not limited to this.
First, the arm 4 is rotated by the control means 5 to cause the transfer head 3 (and displacement sensor 6) to pass over the hole H of the carrier C disposed on the lower surface plate LT of the double-sided polishing device 2. , the inner peripheral edge of the hole H is detected by the displacement sensor 6.
Here, FIG. 5 is an explanatory diagram showing an example of detection of the inner peripheral edge of the hole H by the displacement sensor 6 in plan view. It shows the state at the start of detection of the inner peripheral edge of hole H and after the detection ends. In FIG. 5, the circle indicates the inner peripheral edge (edge) of the hole H, and a, b, c, and d indicate the four displacement sensors 6 disposed on the transfer head 3, and each of the vertices of an approximately square It is located at. Further, the control means 5 sets a virtual XY plane whose X axis is a line connecting the circled number 0 (the fulcrum of the arm 4) to the sun gear SG side (the center of the sun gear SG). Here, the transport head 3 is moved along the X axis.

When the transfer head 3 is passed over the carrier C, first, the transfer head 3 holding the wafer W is rotated to a detection start position where the appropriately determined hole H and the transfer head 3 overlap. Then, the transport head 3 is moved while the distance between the surface of the carrier C and the displacement sensor 6 is measured by irradiating a laser beam directly below the surface of the carrier C from the displacement sensor 6 . The inner peripheral edge of the hole H is detected from the variation in the measured distance as described with reference to FIG. In the example of FIG. 5, displacement sensors a and d detect an upward step from the hole H to the surface of the carrier C, and displacement sensors b and c detect a downward step from the surface of the carrier C to the hole H.
Then, the position data (PQRS) of the displacement sensor 6 (all abcd) when the inner peripheral edge of the hole H is detected is acquired from the control section of the control means 5 or the like.

Next, the calculation unit of the control means 5 calculates the center position of the hole H from the four acquired position data. This calculation step may include, for example, the following steps. FIG. 6 is an explanatory diagram of this calculation process. FIG. 6(1) shows the following steps A to C, and FIG. 6(2) shows the following step D and the average calculation step.
(Process A)
A combination of three position data is selected from among the above four position data (PQRS).
For example, combinations such as QRS and PRS are possible, but here QRS is selected first.
(Process B)
A triangle consisting of two short sides and one hypotenuse is constructed from the combination of the three selected position data.
Here, it is assumed to be △QRS. The two short sides are QR and RS, and one hypotenuse is QS.
(Process C)
The intersection of the perpendicular bisectors of each of the two short sides is obtained as a candidate for the center position of the hole H.
Here, T1 is a candidate for the center position of hole H.
(Process D)
By selecting three combinations of position data different from those selected in step A and repeating steps B and C, one or more different candidates for the center position of hole H are obtained.
For example, select PQR, PRS, and PQS, respectively, and similarly obtain candidates T2, T3, and T4. Although it is sufficient to obtain one or more candidates in addition to T1, it is preferable to have a larger number of candidates because the center position of the hole H can be calculated more accurately.
(Average calculation process)
The center position of the hole H is calculated from the average of all candidates for the center position of the hole H obtained in steps A to D.
Here, the center position T of the hole H is calculated as the average value (coordinates) of T1-T4.

Based on the center position T of the hole H calculated in this way, the control section of the control means 5 controls the position of the transfer head 3 that holds the wafer W via the arm 4. For example, the arm 4 is rotated so that the center of the transfer head 3 (the center of the held wafer W) coincides with the center position T of the hole H. Thereafter, the wafer W is removed from the transfer head 3 and transferred into the hole H of the carrier C.
According to the transport method of the present invention as described above, the wafer W can be accurately transported and loaded into the hole H of the carrier C of the double-sided polishing apparatus 2 easily and inexpensively using low-cost, space-saving equipment.

Note that the present invention is not limited to the above embodiments. The above-mentioned embodiments are illustrative, and any embodiment that has substantially the same configuration as the technical idea stated in the claims of the present invention and has similar effects is the present invention. within the technical scope of the invention.

1... Conveyance device of the present invention, 2... Double-sided polishing device, 3... Conveyance head,
4... Arm, 5... Control means, 6, a, b, c, d... Displacement sensor,
7...Wafer cassette,
C...Carrier, H...Hole of carrier, UT...Upper surface plate, LT...Lower surface plate,
SG...Sun gear, IG...Internal gear, PP...Polishing cloth,
I...insert, W...wafer,
P, Q, R, S...position data of the displacement sensor when detecting the inner edge of the hole,
T1, T2, T3, T4...Candidates for the center position of the hole,
T... Average value of hole center position candidates (calculated hole center position).

Claims (6)

A transport method for transporting a wafer to a hole in a carrier disposed between upper and lower surface plates of a wafer processing device, the method comprising:
passing a transfer head holding the wafer over the carrier by rotating a rotatable arm to which the transfer head is attached;
When passing over the carrier, a displacement sensor disposed on the transport head detects the inner peripheral edge of the hole from the transport head side based on the height difference between the surface of the carrier and the hole;
A control means for controlling the position of the arm calculates the center position of the hole from the position data of the displacement sensor when the inner peripheral edge of the hole is detected, and based on the calculated center position of the hole, the wafer is A transfer method characterized in that the wafer is transferred into a hole of the carrier by controlling the position of the transfer head holding the wafer via the arm. 2. The transport method according to claim 1, wherein the displacement sensor is a laser sensor. The four displacement sensors are arranged at equal intervals along the outer periphery of the transport head,
a step A of selecting a combination of three position data from among four position data of the displacement sensor when detecting the inner peripheral edge of the hole;
Step B of configuring a triangle consisting of two short sides and one hypotenuse from the combination of the three selected position data;
step C of obtaining the intersection of the perpendicular bisectors of each of the two short sides as a candidate for the center position of the hole;
Step D of obtaining one or more different candidates for the center position of the hole by selecting three combinations of position data different from those selected in Step A and repeating Steps B and C;
3. An average calculation step of calculating the center position of the hole from an average of all candidates for the center position of the hole obtained in the steps A to D. Transport method as described. A transport device that transports a wafer to a hole in a carrier disposed between an upper and lower surface plate of a wafer processing device,
It has a transfer head that holds the wafer, a rotatable arm to which the transfer head is attached, and a control means that controls the position of the arm,
A displacement sensor is disposed on the transfer head,
The displacement sensor is capable of detecting the inner peripheral edge of the hole based on the height difference between the surface of the carrier and the hole from the side of the transfer head passing over the carrier by the arm,
The control means calculates the center position of the hole from position data of the displacement sensor when detecting the inner peripheral edge of the hole, and controls the transfer head that holds the wafer based on the calculated center position of the hole. 1. A conveyance device characterized in that the position of the conveyance device is controllable via the arm. 5. The conveying device according to claim 4, wherein the displacement sensor is a laser sensor. The four displacement sensors are arranged at equal intervals along the outer periphery of the transport head,
The control means includes a control unit that controls the arm, a data processing unit that acquires position data of the displacement sensor, and a calculation unit that includes a program that calculates a center position of the hole of the carrier from the position data. It has
The program of the arithmetic unit is
a step A of selecting a combination of three position data from among four position data of the displacement sensor when detecting the inner peripheral edge of the hole;
Step B of configuring a triangle consisting of two short sides and one hypotenuse from the combination of the three selected position data;
step C of obtaining the intersection of the perpendicular bisectors of each of the two short sides as a candidate for the center position of the hole;
Step D of obtaining one or more different candidates for the center position of the hole by selecting three combinations of position data different from those selected in Step A and repeating Steps B and C;
Claim characterized in that it includes an average calculation step of calculating the center position of the hole from the average of all candidates for the center position of the hole obtained in the steps A to D. 4. The conveying device according to claim 4 or claim 5.

Images