Wafer processing system

Abstract

To provide a wafer processing system capable of improving throughput.SOLUTION: A wafer processing system according to the present invention includes a base plate 80, a grinding unit 16 mounted on the base plate 80 and grinding the edge WA of a wafer W, a measuring unit 20 mounted on the base plate 80 and measuring the shape of the ground edge WA of the wafer W, a loading unit 14 for transporting the wafer W between the grinding unit 16 and the measuring unit 20, and a vibration isolation table 90 arranged between the base plate 80 and the measuring unit 20.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a wafer processing system including a grinding unit for grinding an end portion of a wafer and a measuring unit for measuring the shape of the end portion of the wafer.

Background Art

[0002] When a disk-shaped wafer is surface-processed by a polishing apparatus, the end portion of the wafer is processed into a sharp shape, which may cause cracking or chipping of the wafer. Therefore, a grinding process (also referred to as chamfering) is performed on the wafer to remove the sharp portion at the end of the wafer and make the end portion into a round shape or a chamfered shape (see Patent Document 1).

[0003] The shape and dimensions of the end portion of the wafer formed by the grinding process are defined by the standards determined by industry groups or the requirements of clients. Therefore, it is necessary to grind the end portion within the defined range. For this reason, in the wafer manufacturing process, after the grinding process, the shape of the end portion of the wafer is measured, and shape measurement is performed to inspect whether the shape of the end portion is within the defined range.

[0004] Patent Document 2 discloses a shape measurement apparatus for measuring the shape of the end portion of a wafer by a light projection measurement method. This shape measurement apparatus projects light from directions substantially parallel to the front and back surfaces of the wafer onto the end portion of the ground wafer, and at the same time, images the projected image of the end portion of the wafer with a camera from a direction opposite to the light projection direction, and measures the shape of the end portion of the wafer based on the projected image.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Generally, the grinding process of a wafer is performed by a grinding device installed at the processing site. In addition, the shape measurement of the edge of the wafer performed after the grinding process is carried out by a shape measurement device installed in a precision measurement room at a location different from the processing site. The reason for this is that the precision measurement room has less floor vibration than the processing site, in order to avoid measurement errors caused by floor vibration.

[0007] As described above, conventionally, the grinding process and the shape measurement are carried out at separate locations. For this reason, a wafer transfer process for transferring the wafer between the processing site and the precision measurement room must be provided in the wafer manufacturing process, so there is a problem that the production volume (throughput) per unit time of the wafer decreases. Specifically, conventionally, the wafers after the grinding process are sequentially accommodated in a cassette, and a plurality of wafers for one lot are accommodated in this cassette. After that, it is necessary to transfer this cassette from the processing site to the precision measurement room, take out the wafer from the cassette, and measure the shape with a shape measurement device. In this case, even if there is insufficient grinding, it took even more time to return the wafer from the shape measurement device to the grinding device.

[0008] The present invention has been made in view of such circumstances, and an object thereof is to provide a wafer processing system capable of improving throughput.

Means for Solving the Problems

[0009] The present invention comprises the following aspects in order to achieve the above object.

[0010] The wafer processing system according to the first aspect includes a surface plate, a grinding unit mounted on the surface plate for grinding the edge of the wafer, a measurement unit mounted on the surface plate for measuring the shape of the edge of the ground wafer, a transfer unit for transferring the wafer between the grinding unit and the measurement unit, and a vibration isolation table disposed between the surface plate and the measurement unit.

[0011] In the wafer processing system according to the second aspect, in the first aspect, the grinding unit includes a grinding table on which the wafer is placed and that rotates the wafer, and a grindstone that is relatively brought into contact with an end portion of the wafer placed on the grinding table to grind the end portion. The measurement unit includes a measurement table on which the wafer is placed and that rotates the wafer, and a shape measurement device that measures the shape of an end portion of the wafer placed on the measurement table.

[0012] In the wafer processing system according to the third aspect, in the second aspect, it has a first sensor for measuring the diameter of the wafer and the center position of the wafer with respect to the measurement table. The surface plate has a second sensor for measuring the center position of the wafer with respect to the surface plate. Based on the difference between the two center positions measured by the first sensor and the second sensor, and the relative positions of the respective rotation centers of the measurement table and the grinding table set in advance, it has a control device for controlling the conveyance amount of the wafer by the conveyance unit.

[0013] In the wafer processing system according to the fourth aspect, in any one of the first aspect to the third aspect, the measurement unit is provided with a shape measurement device, and the shape measurement device includes an optical unit that is a white interference microscope.

[0014] In the wafer processing system according to the fifth aspect, in any one of the first aspect to the third aspect, the vibration isolation table is moved between a seating position that is a non-operating position and a floating position that is located above the seating position and is an operating position, and has a locking member that fixes the vibration isolation table in the floating position and releases the fixing.

Advantages of the Invention

[0015] According to the present invention, the throughput can be improved.

Brief Description of the Drawings

[0016]

Figure 1

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Figure 12

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Figure 14

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Figure 16

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0018] 〔Wafer Processing System〕

[0019] FIG. 1 is a plan view showing a schematic configuration of a wafer processing system 10. In the following description, among the three mutually perpendicular XYZ directions shown in the figure, the X direction and the Z direction indicate horizontal directions, and the Y direction indicates the vertical (perpendicular) direction.

[0020] As shown in FIG. 1, the wafer processing system 10 includes a cassette unit 12, a load unit 14, a grinding unit 16, a cleaning unit 18, a measurement unit 20, and a transfer unit 22. The load unit 14, the grinding unit 16, and the measurement unit 20 are examples of the transfer unit, the grinding unit, and the measurement unit of the present invention, respectively.

[0021] The load unit 14 transfers a wafer W (shown in FIGS. 2 and 3, etc.) between the cassette unit 12, the grinding unit 16, and the measurement unit 20. This operation is performed by a supply / retrieval robot. The cassette unit 12 is provided with a wafer cassette in which a large number of wafers W to be chamfered are stored. The supply / retrieval robot takes out the wafers W one by one from the wafer cassette and stores the chamfered wafers W in the wafer cassette.

[0022] The supply / retrieval robot includes a three-axis rotary transfer arm, and this transfer arm is provided with a suction pad (not shown) on its upper surface portion. The transfer arm holds the wafer W by vacuum-sucking the lower surface of the wafer W with this suction pad. That is, the transfer arm of this supply / retrieval robot can move back and forth, up and down, and rotate while holding the wafer W, and transfers the wafer W by combining these operations.

[0023] The grinding unit 16 performs grinding of the edge of the wafer W, that is, from rough machining to finish machining.

[0024] FIG. 2 is a schematic configuration diagram showing a schematic configuration of a grinding device (chamfering device) 30 installed in the grinding unit 16. As shown in FIG. 2, the grinding device 30 includes a grinding table 32 for holding the wafer W, a grindstone 34, and a spindle motor 36 for rotating the grindstone 34.

[0025] The grinding table 32 has a holding surface 32a on its upper surface for sucking and holding the wafer W. The grinding table 32 is configured to be rotatable about an axis P1 parallel to the Y direction of the rotary shaft 38 by various actuators such as a motor drive mechanism (not shown). Note that the grinding table 32 is an example of the grinding table of the present invention.

[0026] In the grinding table 32, the wafer W is held in a state where the center P2 of the wafer W is aligned with the axis P1 of the rotary shaft 38. Note that the centering process for aligning the center P2 of the wafer W with the axis P1 of the rotary shaft 38 is performed by the measuring unit 20 or the like, which will be described later.

[0027] The grindstone 34 is configured to be rotatable about an axis parallel to the Y direction by a spindle motor 36. Further, the grindstone 34 is moved forward and backward in the Z direction relative to the end WA of the wafer W (including the edge portion WB and the notch portion WC to be described later; the same applies hereinafter) held by the grinding table 32. When the grindstone 34 is moved forward, the rotating grindstone 34 is relatively pressed against the outer peripheral portion, which is the end WA of the rotating wafer W, and the outer peripheral portion of the wafer W is ground. The grindstone 34 in this example is a total grindstone having a grinding groove 34a on its outer peripheral portion, and the shape of the grinding groove 34a is transferred to the outer peripheral portion of the wafer W during grinding. Note that the grindstone 34 is an example of the grindstone of the present invention.

[0028] The grinding unit 16 is provided with, in addition to the above-described grindstone (coarse grinding grindstone) 34, a finish grinding grindstone (not shown). Thereby, after the outer peripheral portion of the wafer W is roughly processed with the grindstone 34, chamfering for finish grinding of the outer peripheral portion of the wafer W is performed with the finish grinding grindstone.

[0029] Further, the grinding apparatus 30 is provided with a notch rough grinding grindstone and a notch finish grinding grindstone for grinding the notch portion WC (see FIG. 3). Thereby, for the notch portion WC, after rough processing with the notch rough grinding grindstone, chamfering as finish grinding is performed with the notch finish grinding grindstone. Note that a plurality of grinding apparatuses 30 may be installed in the grinding unit 16.

[0030] Returning to FIG. 1, the cleaning unit 18 cleans the wafer W after chamfering. This cleaning unit 18 includes a spin cleaning device (not shown). The spin cleaning device sprays a cleaning liquid onto the upper surface (front surface) of the wafer W while rotating the wafer W held on the cleaning table, and peels off and removes the dirt adhering to the upper surface of the wafer W.

[0031] The transfer unit 22 transfers the wafer W between the grinding unit 16 and the cleaning unit 18. The transfer unit 22 includes a transfer robot configured to be capable of linear motion in the Z direction and lifting motion in the Y direction (vertical direction). The transfer robot includes an arm portion, and a suction pad is provided at the tip thereof. The transfer robot transfers the wafer W while sucking the upper surface of the wafer W with the suction pad of the arm portion. Thus, in the transfer unit 22, the transfer robot transfers the wafer W chamfered by the grinding unit 16 to the cleaning unit 18, or transfers the wafer W cleaned by the cleaning unit 18 to the grinding unit 16.

[0032] FIG. 3 is a plan view of the wafer W. As shown in FIG. 3, an edge portion WB is formed along the circumferential direction on the outer peripheral portion which is the end portion WA of the wafer W, and a notch portion WC is formed on a part of the outer peripheral portion. The notch portion WC is a notch portion for indicating the silicon crystal orientation of the wafer W, and like the edge portion WB, is an object of grinding and shape measurement.

[0033] FIG. 4 is an explanatory diagram showing the configuration of the measurement unit 20. In the measurement unit 20, the above-mentioned centering process is performed, which will be described later. First, the configuration for measuring the shape of the end portion WA (edge portion WB and notch portion WC) of the wafer W will be described.

[0034] As shown in FIG. 4, a shape measurement device 54 is provided in the measurement unit 20 of this example. This shape measurement device 54 calculates three-dimensional shape data indicating height information (such as surface shape and surface roughness) of the measured surface of the end WA (edge portion WB and notch portion WC) of the wafer W, which is the object to be measured, based on a plurality of captured images captured at regular pitches while scanning an optical unit 60 described later in the scanning direction (Z direction).

[0035] The shape measurement device 54 generally includes an optical unit 60, a measurement table 52, and a control device 100.

[0036] The measurement table 52 has a holding surface 52a for sucking and holding the wafer W on its upper surface. The measurement table 52 is configured to be rotatable about an axis P3 parallel to the Y direction by a table drive unit 65. The table drive unit 65 is composed of various actuators such as a motor drive mechanism. Note that the measurement table 52 is an example of the measurement table of the present invention.

[0037] The optical unit 60 is disposed on the left side of the measurement table 52 in the Z direction. This optical unit 60 images the end WA of the wafer W at predetermined pitches while relatively scanning the end WA of the wafer W in the Z direction (the left-right direction in FIG. 4). Note that the shape measurement device 54 is an example of the shape measurement device of the present invention.

[0038] Next, the configuration of the optical unit 60 will be described. FIG. 5 is a schematic diagram showing the details of the configuration of the optical unit 60.

[0039] The optical unit 60 is a Michelson-type white light interference microscope. This optical unit 60 includes a camera 66, a light source unit 68, a beam splitter 70, an interference objective lens 72, and an imaging lens 74. Note that the optical unit 60 is an example of the optical unit of the present invention.

[0040] In FIG. 5, an interference objective lens 72, a beam splitter 70, an imaging lens 74, and a camera 66 are arranged in this order along the left side in the Z direction from the end WA of the wafer W. Further, a light source unit 68 is arranged at a position facing the beam splitter 70 in the Y direction.

[0041] Under the control of the control device 100, the light source unit 68 emits white light (low-coherence light with little coherence) in a parallel light beam toward the beam splitter 70 as measurement light L1. The light source unit 68 includes, although not shown, a light source capable of emitting measurement light L1 such as a light-emitting diode, a semiconductor laser, a halogen lamp, and a high-intensity discharge lamp, and a collector lens that converts the measurement light L1 emitted from this light source into a parallel light beam.

[0042] For example, a half mirror is used as the beam splitter 70. The beam splitter 70 reflects a part of the measurement light L1 incident from the light source unit 68 toward the interference objective lens 72 on the right side in the Z direction. Further, the beam splitter 70 transmits the combined light L3, which will be described later, incident from the interference objective lens 72 to the left side in the Z direction and emits the combined light L3 toward the imaging lens 74.

[0043] The interference objective lens 72 is of the Michelson type and includes an objective lens 72A, a beam splitter 72B, and a reference surface 72C.

[0044] In FIG. 5, the beam splitter 72B and the objective lens 72A are arranged in this order along the left side in the Z direction from the end WA of the wafer W. Further, the reference surface 72C is arranged at a position facing the beam splitter 72B in the Y direction. Hereinafter, the description will be made using a Michelson-type interference optical system, but the interference optical system is not limited to the Michelson type, and known interference optical systems such as the Mirau type and the Linnik type can be adopted.

[0045] The objective lens 72A has a condensing action and condenses the measurement light L1 incident from the beam splitter 70 onto the measurement surface of the end WA of the wafer W through the beam splitter 72B.

[0046] The beam splitter 72B is, for example, a half mirror. The beam splitter 72B splits a part of the measurement light L1 incident from the objective lens 72A as the reference light L2, transmits the remaining measurement light L1, emits it to the end WA of the wafer W, and reflects the reference light L2 toward the reference surface 72C. The measurement light L1 transmitted through the beam splitter 72B is irradiated onto the measurement surface of the end WA of the wafer W, and then reflected by the measurement surface and returns to the beam splitter 72B.

[0047] The reference surface 72C is, for example, a reflection mirror, and reflects the reference light L2 incident from the beam splitter 72B toward the beam splitter 72B. The position of this reference surface 72C in the Y direction can be manually adjusted by a position adjustment mechanism (not shown). Thereby, the optical path length of the reference light L2 between the beam splitter 72B and the reference surface 72C can be adjusted. The optical path length of the reference light L2 is adjusted to be equal (including substantially equal) to the optical path length of the measurement light L1 between the beam splitter 72B and the measurement surface.

[0048] The beam splitter 72B generates a combined light L3 of the measurement light L1 returning from the measurement surface and the reference light L2 returning from the reference surface 72C, and emits this combined light L3 toward the objective lens 72A on the left side in the Z direction. This combined light L3 passes through the objective lens 72A and the beam splitter 70 and is incident on the imaging lens 74. In the case of a white light interference microscope, the combined light L3 becomes interference light including interference fringes.

[0049] The imaging lens 74 forms an image of the combined light L3 incident from the beam splitter 70 on the imaging surface (not shown) of the camera 66. Specifically, the imaging lens 74 forms an image of a point on the focal plane of the objective lens 72A as an image point on the imaging surface of the camera 66.

[0050] The camera 66 has an imaging device of the CCD (Charge Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type, although not shown in the figure. While the optical unit 60 is being driven (scanned) by the optical unit drive unit 62, the camera 66 captures the combined light L3 imaged on the imaging surface by the imaging lens 74.

[0051] The optical unit drive unit 62 is composed of various actuators such as a linear motor or a motor drive mechanism, and holds the optical unit 60 so as to be movable in the Z direction, which is the scanning direction. Under the control of the control device 100, this optical unit drive unit 62 scans the optical unit 60 along the Z direction. Further, the optical unit drive unit 62 holds the optical unit 60 so as to be movable in the Y direction and the X direction, and enables adjustment of the relative position of the optical unit 60 with respect to the wafer W.

[0052] The scale 64 is a position detection sensor that detects the Z-direction position of the optical unit 60 with respect to the wafer W. For example, a linear scale is used. This scale 64 repeatedly detects the Z-direction position of the optical unit 60 and repeatedly outputs the position detection result to the control device 100.

[0053] 〔Control Device〕 Next, the configuration of the control device 100 will be described. FIG. 6 is a functional block diagram of the control device 100. As shown in FIG. 6, the light source unit 68 and the camera 66, the scale 64, the table drive unit 65, the optical unit drive unit 62, the operation unit 110, and the output unit 120 of the optical unit 60 are connected to the control device 100.

[0054] The operation unit 110 includes operation members (for example, a keyboard and a mouse, etc.) for receiving an operator's operation input to the control device 100.

[0055] The output unit 120 is a device for outputting the execution results of programs, data of calculation results, etc. by the control device 100. The output unit 120 includes, for example, an operation UI (User Interface) and a monitor (e.g., a liquid crystal display, etc.) for displaying detection results. Further, the output unit 120 may include a printer, a speaker, etc. in addition to or instead of the monitor.

[0056] The control device 100 controls the measurement operation of the three-dimensional shape of the surface to be measured by the shape measurement device 54 in response to an operation input from the operation unit 110, and performs operations such as calculation of the three-dimensional shape of the surface to be measured. The control device 100 includes a processor (e.g., a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc.) that executes various operations, a memory (e.g., a ROM (Read Only Memory) and a RAM (Random Access Memory), etc.) that serves as a working area for the processor, and a storage device (e.g., an SSD (Solid State Drive) or an HDD (Hard Disk Drive), etc.) for storing various programs and data.

[0057] The control device 100 functions as a measurement control unit 140 and a shape data generation unit 150 by executing the program stored in the storage device by the processor. Further, the control device 100 includes a storage unit 162 configured by the above-described storage device (memory is also acceptable).

[0058] The measurement control unit 140 controls the table drive unit 65, the optical unit drive unit 62, the camera 66, and the light source unit 68 to repeatedly image the end portion WA of the wafer W by the camera 66 at a constant pitch while scanning the optical unit 60 in the scanning direction (Z direction). Specifically, the measurement control unit 140 controls the table drive unit 65 to rotate the measurement table 52 so that the end portion WA (edge portion 80 or notch portion 82) of the wafer W to be measured faces the optical unit 104. Further, after starting the emission of the measurement light L1 from the light source unit 68, the measurement control unit 140 controls the optical unit drive unit 62 to scan the optical unit 60 in the Z direction. Further, while the optical unit drive unit 62 scans the optical unit 60 in the Z direction, the measurement control unit 140 repeatedly executes imaging of the combined light L3 by the camera 66 and output of the captured image to the control device 100 every time the optical unit 60 moves by a constant pitch in the Z direction based on the detection result of the Z-direction position of the optical unit 60 by the scale 64.

[0059] Each time the camera 66 images the combined light L3, the shape data generation unit 150 acquires the captured image output from the camera 66 and generates three-dimensional shape data of the measurement surface of the end portion WA of the wafer W. Specifically, the shape data generation unit 150 compares the luminance values of the pixels at the same coordinates of each captured image. Next, the shape data generation unit 150 determines the Z-direction position where the luminance value is maximized for each pixel at the same coordinates of each captured image, thereby calculating height information indicating the height position (Z-direction position) of each part of the measurement surface corresponding to each pixel. Thereby, three-dimensional shape data indicating the three-dimensional shape (height distribution) of the measurement surface W is generated.

[0060] 〔Outline of the operation of the wafer processing system〕 Next, an outline of the operation of the wafer processing system 10 of the present embodiment will be described. FIG. 7 is a flowchart showing an outline of the operation of the wafer processing system 10.

[0061] First, the wafer W is taken out from the cassette attached to the cassette unit 12 by the supply / retrieval robot of the load unit 14 and conveyed to the measurement unit 20. The wafer W conveyed to the measurement unit 20 is placed on the measurement table 52 of the measurement unit 20 (step S1: wafer placement process).

[0062] Next, in the measurement unit 20, the diameter and the amount of eccentricity of the wafer W placed on the measurement table 52 are measured (step S2: diameter and amount of eccentricity measurement process). The above-mentioned amount of eccentricity is the amount of deviation of the center P1 of the wafer W with respect to the axis P1 of the grinding table 32 when the wafer W is placed on the grinding table 32. The process performed in step S2 corresponds to a centering process for aligning the center P2 of the wafer W with the axis P1 of the grinding table 32. This centering process will be described later.

[0063] Next, the wafer W whose diameter and amount of eccentricity have been measured in the measurement unit 20 is conveyed from the measurement unit 20 to the grinding unit 16 by the supply / retrieval robot of the load unit 14. The wafer W conveyed to the grinding unit 16 is placed on the grinding table 32 of the grinding unit 16 (step S3: wafer placement process).

[0064] At this time, the control device 100 corrects the distance (known relative position) between the axis P1 of the grinding table 32 and the axis P3 of the measurement table 52, which is a known distance, by the amount of eccentricity obtained in step S2, and controls the conveyance amount of the wafer W by the supply / retrieval robot based on this corrected distance (corrected relative position).

[0065] As a result, the wafer W is placed on the grinding table 32 in a state where the center P2 of the wafer W is aligned with the axis P1 of the grinding table 32. The above-mentioned known relative position is measured in advance and stored in the storage unit 160.

[0066] Next, in the grinding section 16, the end portion WA of the wafer W is ground (chamfered) by the grinding device 30. Specifically, after the edge portion WB, which is the outer peripheral portion of the wafer W, is roughly processed with a grindstone 34, chamfering for finish grinding of the outer peripheral portion of the wafer W is performed with a finish grinding grindstone. Also, for the notch portion WC of the wafer W, after rough processing with a notch rough grinding grindstone, chamfering as finish grinding is performed with a notch finish grinding grindstone (Step S4: Grinding process).

[0067] Next, the wafer W for which the grinding (chamfering) has been completed in the grinding section 16 is transported from the grinding section 16 to the cleaning section 18 by the transport robot of the transport section 22. Then, in the cleaning section 18, the wafer W is cleaned by the spin cleaning device (Step S5: Cleaning process).

[0068] Next, the wafer W for which the cleaning has been completed in the cleaning section 18 is transported from the cleaning section 18 to the grinding section 16 by the transport robot of the transport section 22. Thereafter, the wafer W is transported from the grinding section 16 to the measurement section 20 by the supply / retrieval robot of the load section 14. The wafer W transported to the measurement section 20 is placed on the measurement table 52 (Step S6: Transport process to the measurement section).

[0069] Next, in the measurement section 20, the three-dimensional shape of the end portion WA of the wafer W is measured by the shape measurement device 54 (Step S7: Shape measurement process). Specifically, the measurement control unit 140 controls each part to scan the optical unit 60 relative to the end portion WA of the wafer W in the scanning direction (Z direction) while imaging the end portion WA of the wafer W with the camera 66 at predetermined pitches. Next, the shape data generation unit 150 generates three-dimensional shape data indicating the surface shape of the end portion WA of the wafer W based on a plurality of captured images captured by the camera 66. The measurement result of the measurement section 20 (the three-dimensional shape of the end portion WA of the wafer W) is output to the output section 120. Note that the control device 100 may calculate a determination result indicating whether or not the measurement result of the measurement section 20 is within a predetermined specified range and output the determination result to the output section 120.

[0070] Next, the inspected wafer W is transported from the measurement unit 20 to the cassette unit 12 by the supply / retrieval robot in the load unit and stored in the cassette (step S8: cassette storage process). Before transporting the wafer W from the measurement unit 20 to the cassette unit 12, it is preferable to measure the diameter and the amount of core deviation of the wafer W again in the measurement unit 20. Thereby, the wafer W can be stored at the correct position in the cassette. Further, when the shape of the end portion WA of the wafer W is outside the specified range, the wafer W may be returned to the grinding unit 16 and reground.

[0071] By the way, in order to improve the throughput (productivity of the wafer W), it is desirable to perform the grinding process and the shape measurement of the wafer W in the same system (on the same surface plate).

[0072] In other words, it is desirable to mount (arrange side by side) the grinding unit 16 and the measurement unit 20 on the same surface plate, and immediately measure the shape of the wafer W that has been finished grinding in the grinding unit 16 with the measurement unit 20 (via the cleaning unit 18). According to this configuration, the wafer transfer process (including the process of returning the wafer from the measurement unit 20 to the grinding unit 16 in the case of insufficient grinding) performed between the grinding unit 16 and the measurement unit 20 can be shortened, so that the throughput can be improved.

[0073] Here, before explaining the configuration of the wafer processing system 10 of the present embodiment, several comparative examples (Comparative Examples 1 and 2) will be described.

[0074] [Comparative Example 1] Comparative Example 1 is shown in FIG. 8. FIG. 8 shows a configuration when the grinding unit 16 and the measurement unit 20 are simply arranged side by side on the same surface plate 80.

[0075] However, in the configuration of Comparative Example 1, the floor vibration A is transmitted from the floor surface 82 at the processing site to the measurement unit 20 via the surface plate 80. For this reason, the floor vibration A enters the measurement result in the measurement unit 20 as noise, so there is a problem that the measurement accuracy deteriorates (large error).

[0076] [Comparative Example 2] Although illustration is omitted, in Comparative Example 2, in order to suppress the influence of floor vibration A, a vibration isolation table is installed between the floor surface 82 and the surface plate 80, and the floor vibration A transmitted from the floor surface 82 to the measuring unit 20 via the surface plate 80 is reduced (attenuated) by the vibration isolation table.

[0077] However, in the configuration of Comparative Example 2, although the influence of floor vibration A can be suppressed, since the machining vibration generated in the grinding unit 16 is transmitted to the measuring unit 20 via the surface plate 80, there is also a problem that the measurement accuracy deteriorates.

[0078] Due to such circumstances, conventionally, wafer grinding and shape measurement have been performed at separate locations (systems), and as a result, there has been a problem of reduced throughput.

[0079] Therefore, the wafer processing system 10 of the present embodiment has the following configuration in order to solve the above problems.

[0080] [Features of the Wafer Processing System of the Present Embodiment] FIG. 9 is an explanatory diagram for explaining the features of the wafer processing system 10 of the present embodiment.

[0081] As shown in FIG. 9, in the wafer processing system 10 of this example, the grinding unit 16 and the measuring unit 20 are juxtaposed on the surface plate 80, and a vibration isolation table 90 is installed between the surface plate 80 and the measuring unit 20. Further, a load unit 14 and the like shown in FIG. 1 are installed on the surface plate 80. The surface plate 80 is an example of the surface plate of the present invention.

[0082] As shown in FIG. 9, the vibration isolation table 90 is a passive vibration isolation table having a lower base 92 fixed to the surface plate 80, an upper base 94 to which the measuring unit 20 is fixed, a spring element 96 and a damping element 98 provided between the lower base 92 and the upper base 94. The vibration isolation table 90 is an example of the vibration isolation table of the present invention.

[0083] According to the wafer processing system 10 of the present embodiment, with the above configuration, the floor vibration A transmitted from the floor surface 82 to the measuring unit 20 via the surface plate 80 and the machining vibration B transmitted from the grinding unit 16 to the measuring unit 20 via the surface plate 80 can be reduced by the vibration isolator 90.

[0084] Thereby, the wafer processing system 10 of the present embodiment can ensure the measurement accuracy even when the grinding unit 16 and the measuring unit 20 are arranged side by side on the same surface plate 80. That is, the measurement accuracy can be ensured even when the grinding process by the grinding unit 16 and the shape measurement by the measuring unit 20 are simultaneously performed on the same surface plate 80. As a result, the wafer transfer process performed between the grinding unit 16 and the measuring unit 20 can be shortened, so that the throughput can be improved.

[0085] Note that the vibration isolator 90 is not limited to a passive vibration isolator, and for example, an active vibration isolator that performs an operation to cancel external vibration by a motor can also be used. Further, since the measurement table 52 mounted on the vibration isolator 90 is a rotating stage without the movement of the center of gravity, the inclination generated in the vibration isolator 90 can be suppressed as compared with a linear stage with the movement of the center of gravity.

[0086] By the way, when the measuring unit 20 is mounted on the surface plate 80 via the vibration isolator 90, due to the deviation of the return position of the vibration isolator 90, the distance that was originally known, that is, the distance between the axis P3 of the measuring unit 20 and the axis P1 of the grinding unit 16 (hereinafter, also referred to as the relative position) may become non-constant.

[0087] Then, even if only the amount of deviation of the center P2 of the wafer W from the axis P3 of the measuring unit 20 is measured, it may become impossible to align the center P2 of the wafer W with the axis P1 of the grinding table 32 due to the deviation of the above return position.

[0088] Therefore, in order to align the center P2 of the wafer W with the axis P1 of the grinding table 32, it is necessary to perform the following two centering processes (the first centering process and the second centering process) in the measuring unit 20.

[0089] <First centering process> The first centering process is a process of measuring the diameter of the wafer W and the amount of misalignment of the center P2 of the wafer W with respect to the axis P3 of the measurement table 52. In other words, it is a process of obtaining the center C1 of the wafer W in the vibration isolation pedestal coordinate system (XZ coordinate system) with respect to the measurement table 52. Hereinafter, the configuration for performing the first centering process will be briefly described.

[0090] First, the original purpose is to transfer the wafer W from the measurement unit 20 to the grinding unit 16 so that the center P2 of the wafer W coincides with the axis P1 of the grinding table 32.

[0091] Therefore, in advance, the relative position between the axis P1 of the grinding table 32 and the axis P3 of the measurement table 52 is measured and stored in the storage unit 162 of the control device 100.

[0092] Thereafter, the wafer W is taken out from the wafer cassette using the supply / retrieval robot of the load unit 14, transferred to the measurement unit 20, and placed on the measurement table 52. However, since the position of the wafer W in the cassette is unknown, the wafer W is placed in a state of being misaligned with respect to the measurement table 52. Note that the misaligned state means a state in which the center P2 of the wafer W is displaced with respect to the axis P3 of the measurement table 52.

[0093] FIG. 10 shows a diameter sensor 180 for performing the first centering process. This diameter sensor 180 is installed on the upper base 94 of the vibration isolation pedestal 90 and has a light receiving unit 182 and a light projecting unit 184. The light receiving unit 182 and the light projecting unit 184 are arranged to face each other in the Y direction with the wafer W interposed therebetween. Note that the diameter sensor 180 is an example of the first sensor of the present invention.

[0094] As the light receiving unit 182, for example, a CCD camera is applied. The CCD camera can image the outer peripheral portion of the wafer W.

[0095] The CCD camera, which is the light-receiving unit 182, images a plurality of imaging points on the outer peripheral portion of the wafer W while rotating the measurement table 52. In other words, the CCD camera is a sensor that detects the position of the outer peripheral portion of the wafer W placed on the measurement table 52, and outputs to the control device 100 the change in the position of the outer peripheral portion of the wafer W according to the rotation angle of the measurement table 52.

[0096] The image captured by the CCD camera is obtained as a black-and-white binary image. The control device 100 performs image processing on the captured image, and obtains the distance between the axis P3 of the measurement table 52 and the outer peripheral end point (edge) by obtaining the coordinates of the outer peripheral end points (edges) in each image obtained by the image processing. Then, the measurement table 52 is rotated to obtain the distances for a plurality of end points in the circumferential direction of the wafer W, and based on these distances, the diameter of the wafer W and the amount of deviation of the center P2 of the wafer W from the axis P3 of the measurement table 52 (the center C1 of the wafer W in the vibration isolation pedestal coordinate system) are obtained. The above is the first centering step. Note that the distance between the axis P3 of the measurement table 52 and the CCD camera (light-receiving unit 182) in the Z direction is known.

[0097] 〈Second centering step〉 The second centering step is a step of measuring the position of the center P1 of the wafer W with respect to the surface plate 80. In other words, it is a step of obtaining the center C2 of the wafer W in the grinding unit coordinate system (XZ coordinate system) with respect to the surface plate 80. Hereinafter, the configuration for performing the second centering step will be briefly described.

[0098] As shown in FIG. 10, above the measurement table 52, an outer diameter sensor 190 for detecting the outer diameter position of the wafer W is arranged. The outer diameter sensor 190 has two sensors 192 and 194 that are spaced apart from each other on the XZ plane. These sensors 192 and 194 are attached to a pole 196 installed on the surface plate 80 in order to obtain the center C2 of the wafer W in the grinding unit coordinate system. Note that the outer diameter sensor 190 is an example of the second sensor of the present invention.

[0099] FIG. 11 is an explanatory diagram showing the postures of two wafers W placed on the measurement table 52. The wafer W shown by the solid line in FIG. 11 is placed in a state where the center P2 of the wafer W is displaced with respect to the axis P3 of the measurement table 52, and the virtual wafer W shown by the dotted line is placed in a state where the center P2 of the wafer W coincides with the axis P3 of the measurement table 52.

[0100] Also, in FIG. 11, the outer diameter positions of the wafer W detected by the two sensors 192 and 194 are shown as D1 and D2. Also, the diameter of the wafer W obtained in the first centering step is shown as D.

[0101] When the outer diameter positions D1 and D2 of the wafer W are detected by the two sensors 192 and 194, the control device 100 determines the center C2 of the wafer W in the grinding unit coordinate system based on the two outer diameter positions D1 and D2 detected by the sensors 192 and 194 and the diameter D of the wafer W obtained in the first centering step. The above is the second centering step.

[0102] When the above center C2 is obtained, the control device 100 calculates the difference between the center C1 obtained in the first centering step and the center C2 obtained in the second centering step in order to execute the above object (transfer the wafer W from the measurement unit 20 to the grinding unit 16 so that the center P2 of the wafer W coincides with the axis P1 of the grinding table 32), corrects the relative position with the difference, and calculates the transfer amount of the wafer W by the supply and recovery robot based on the corrected relative position (transfer amount calculation step). Then, the wafer W is transferred by the supply and recovery robot based on this transfer amount (transfer step).

[0103] Thereby, even when the return position of the vibration isolation table 90 is displaced, the wafer W can be transferred so that the center P2 of the wafer W coincides with the axis P1 of the grinding table 32.

[0104] Note that, through the first centering process and the second centering process, the process of step S2 shown in FIG. 7 (diameter and core deviation measurement process) is realized. Further, through the above-described conveyance amount calculation process and the conveyance process, the process of step S3 (wafer placement process) is realized.

[0105] 〔Characteristics of Vibration Isolation Table〕 In the vibration isolation table 90, when the vibration isolation table 90 is in the stopped (OFF) state, the upper base 94 is located at the seating position which is the non-operating position. Then, when the vibration isolation table 90 is activated (ON), the upper base 94 rises from the seating position to the floating position which is the operating position. The shape measurement of the wafer W is performed at this floating position. In this case, the wafer W is transferred from the supply and recovery robot to the measurement table 52 at a seating position more stable than the floating position, and then the shape measurement is performed at the floating position.

[0106] However, in such a measurement procedure, there is a problem that it takes time for the upper base 94 to move from the seating position to the floating position.

[0107] Therefore, in order to stably transfer the wafer W to the measurement table 52 while shortening the above time, the upper base 94 of the vibration isolation table 90 is fixed (locked) so as not to be movable at the floating position, the wafer W is transferred to the measurement table 52 in this locked state, and then the lock is released to perform the shape measurement of the wafer W.

[0108] FIG. 12 shows a state in which the upper base 94 of the vibration isolation table 90 located at the floating position is pressed against the stopper wall 210 using an external lock pin 200, thereby locking the upper base 94 so as not to be movable at the floating position. Note that the lock pin 200 is an example of the lock member of the present invention.

[0109] The lock pin 200 and the stopper wall 210 are arranged to face each other in the Z direction with the upper base 94 interposed therebetween. The lock pin 200 is provided so as to be able to move forward and backward in the Z direction with respect to the upper base 94.

[0110] When the locking pin 200 moves forward (see Fig. 12), the upper base 94 is pressed against the stopper wall 210 by the locking pin 200 and is locked in a non-movable state. The wafer W is transferred to the measurement table 52 in this locked state.

[0111] With such a configuration, it is possible to stably transfer the wafer W to the measurement table 52 while shortening (reducing) the time from the seating position to the floating position of the upper base 94. After the upper base 94 is locked, the vibration isolation table 90 may be stopped. In this case, since the upper base 94 is pressed against the stopper wall 210 and locked, it does not return from the floating position to the seating position.

[0112] Also, when the locking pin 200 moves backward, the pressing (locking) of the upper base 94 against the stopper wall 210 is released, so it becomes operable at the floating position. The wafer W is measured for its shape in this unlocked state. Naturally, the vibration isolation table 90 is started before the locking pin 200 moves backward.

[0113] According to the configuration of this example, as described above, the time from the seating position to the floating position of the upper base 94 can be shortened, so it can contribute to the improvement of throughput.

[0114] 〔When an active type vibration isolation table is applied as the vibration isolation table〕 The active type vibration isolation table has a position feedback sensor. This position feedback sensor generally has a dead zone (see Fig. 13) within the return range in order to prevent hunting (chaotic adjustment). Due to the influence of this dead zone, the position of the vibration isolation table mounting portion may not be strictly determined.

[0115] Fig. 13 is an explanatory diagram showing that there is a dead zone within the return range in the active type vibration isolation table. The dead zone is a region where no feedback is given even if it deviates from the neutral position within the dead zone range.

[0116] Therefore, when transferring the wafer W, for example, by using a pressing member to push the vibration isolation table from one side each time to return it to its original position (the return position outside the dead zone: position E1 in FIG. 13), a structure that is not affected by the dead zone is achieved.

[0117] In this case, it is necessary that the speed when separating the pressing member from the vibration isolation table does not exceed the return speed of the vibration isolation table. That is, if the speed when separating the pressing member exceeds the return speed, the vibration isolation table may overrun from the position E2 in FIG. 13 to the position E3 which is the edge of the dead zone and enter the dead zone area. Therefore, the speed when separating the pressing member is set to a slow speed that does not exceed the return speed.

[0118] Also, when a shaft (in the horizontal direction) is mounted on the vibration isolation table, the change in the center of gravity can be utilized instead of pushing. Note that in many cases, when the vibration isolation table is subjected to external disturbances, feedback is applied to return it to the neutral position.

[0119] Hereinafter, several modification examples (the first modification example and the second modification example) will be described.

[0120] 〔The first modification example〕 FIG. 14 is a schematic plan view of a wafer processing system 220 showing the first modification example. FIG. 15 is a schematic side view of the wafer processing system 220 shown in FIG. 14. When explaining the first modification example, members that are the same as or similar to those of the wafer processing system 10 of the present embodiment shown in FIG. 1 are denoted by the same reference numerals and will be described.

[0121] As shown in FIGS. 14 and 15, in the wafer processing system 220 of the first modification example as well, the grinding unit 16 and the measuring unit 20 are mounted on the same surface plate 80. Note that in FIG. 14, the loading unit 14 is also shown.

[0122] As shown in FIG. 15, in the wafer processing system 220 of the first modification example, the measuring unit 20 is installed on the upper side (Y direction side) compared to the grinding unit 16.

[0123] When the wafer W is ground by the grinding unit 16, the grinding chips 230 generated during the grinding process are scattered radially from the wafer W and fall onto the surface plate 80. As in the wafer processing system 220 of the second modification, by installing the measuring unit 20 above the grinding unit 16 in the upward (Y direction), it is possible to prevent the grinding chips 230 from being reflected in the measurement image when the wafer W is imaged by the optical unit 60. In addition, it is possible to prevent the grinding chips 230 from adhering to the wafer W placed on the measurement table 52 of the measuring unit 20 and each sensor (diameter sensor 180 and outer diameter sensor 190) of the measuring unit 20. Thereby, the measurement accuracy can be ensured.

[0124] Here, in the wafer processing system 10 of the present embodiment, the measuring unit 20 is mounted on the surface plate 80 via the vibration isolation table 90, so that the measuring unit 20 is installed above the grinding unit 16 in the upward (Y direction). However, the member for installing the measuring unit 20 above the grinding unit 16 in the upward (Y direction) is not limited to the vibration isolation table 90, and other raising members 240 (see FIG. 15) may be used.

[0125] That is, the configuration of the first modification can also be adopted in a wafer processing system in which the grinding unit 16 and the measuring unit 20 are mounted on the same surface plate 80 and the vibration isolation table 90 is not provided. Even with such a configuration, it is possible to prevent the reflection of the grinding chips 230, and the measurement accuracy can also be ensured.

[0126] Further, as shown in FIG. 14, the shape measuring device 54 in the first modification is preferably disposed at a position separated from the corner portions 80A, 80A of the surface plate 80. Since the grinding chips 230 tend to accumulate in the corner portion 80A, by disposing the optical unit 60 at a position separated from such a corner portion 80A, it is possible to more reliably prevent the reflection of the grinding chips 230.

[0127] 〔Second Modification〕 FIG. 16 is a schematic plan view of a wafer processing system 250 showing a second modification. In describing the second modification, members that are the same as or similar to those of the wafer processing system 10 of the present embodiment shown in FIG. 1 will be described with the same reference numerals.

[0128] As shown in FIG. 16, also in the wafer processing system 250 of the second modification, the grinding unit 16 and the measuring unit 20 are mounted on the same surface plate 80. Note that the loading unit 14 is also shown in FIG. 16.

[0129] In the wafer processing system 250 shown in FIG. 16, the machining vibration B generated in the grinding unit 16 propagates along the rotational direction indicated by the arrow of the grinding table 32. The white interference microscope, which is the optical unit 60, has a characteristic that the resolution in the direction along the optical axis (Z1) is superior to the resolution in the direction orthogonal to the optical axis (Z1).

[0130] In consideration of such characteristics, on the XZ plane, the white interference microscope is arranged such that the optical axis (Z1) of the white interference microscope faces the grinding unit 16. Then, since the machining vibration B propagates along the direction substantially orthogonal to the optical axis (Z1), it is possible to measure the shape of the wafer W without being affected by the machining vibration B. As a result, the measurement accuracy by the measuring unit 20 can be ensured.

[0131] Here, "such that the optical axis (Z1) of the white interference microscope faces the grinding unit 16" means that the optical axis (Z1) faces within the arrangement area of the measurement table 52, preferably that the optical axis (Z1) faces the axis center P1 of the measurement table 52. However, as long as it is a range that is hardly affected by the machining vibration B, the optical axis (Z1) may face outside the arrangement area of the measurement table 52.

[0132] Also in the configuration of the second modification example, similar to the configuration of the first modification example, it is a wafer processing system in which the grinding unit 16 and the measuring unit 20 are mounted on the same workbench 80, and it can also be adopted in a wafer processing system not provided with a vibration isolation table. Even with such a configuration, it is possible to measure the shape of the wafer W without being affected by the machining vibration B.

[0133] Incidentally, as a reference example, the wafer W can be centered using the diameter sensor 180 shown in FIG. 10. Also, the wafer W can be centered using a dedicated centering sensor. The dedicated centering sensor has, for example, two sensors that detect two separated points on the outer peripheral portion of the wafer W, and when the two sensors simultaneously detect the outer peripheral portion of the wafer W, it is determined that the wafer W is centered.

[0134] In the above-described embodiment, in the measuring unit 20, the configuration including a shape measuring device having a white light interference microscope has been described as an example, but it is not limited thereto. For example, it may include a shape measuring device having a microscope such as a focus variation method microscope or a laser confocal method microscope, or it may include a shape measuring device using a light projection measurement method.

[0135] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above examples, and of course, various improvements or modifications may be made without departing from the gist of the present invention.

Description of Reference Numerals

[0136] 10…Wafer processing system, 12…Cassette section, 14…Load section, 16…Grinding section, 18…Washing section, 20…Measuring section, 22…Conveyor section, 30…Grinding device, 32…Grinding table, 32a…Holding surface, 34…Grinding wheel, 34a…Grinding groove, 36…Spindle motor, 38…Rotating shaft, 52…Measuring table, 52a…Holding surface, 54…Shape measuring device, 60…Optical unit, 62…Optical unit drive section, 64…Scale, 65…Table drive section, 66…Camera, 68…Light source section, 70…Beam splitter, 72…Interference objective lens, 72A…Objective lens, 72B…Beam splitter, 72C…Reference surface, 74…Imaging lens, 80…Surface plate, 80A…Corner section, 90…Vibration isolation table, 92…Lower base, 94…Upper base, 96…Spring element, 98…Damping element, 100…Control device, 110…Operation section, 120…Output section, 150…Shape data generation section, 180…Diameter sensor, 182…Light receiving section, 184…Light projecting section, 190…Outer diameter sensor, 192…Sensor, 194…Sensor, 200…Lock pin, 210…Stopper wall, 220…Wafer processing system, 230…Grinding chips, 240…Build-up member, 250…Wafer processing system, A…Floor vibration, B…Processing vibration, D…Diameter, D1…Outer diameter position, D2…Outer diameter position, E1…Position of vibration isolation table, E2…Position of vibration isolation table, E3…Position of vibration isolation table, W…Wafer, WA…End portion, WB…Edge portion, WC…Notch portion, P1…Axis center, P2…Center, P3…Axis center

Claims

1. A surface plate, A grinding unit mounted on the surface plate for grinding an end portion of a wafer, A measuring unit mounted on the surface plate for measuring the shape of the end portion of the ground wafer, A transfer unit for transferring the wafer between the grinding unit and the measuring unit, A vibration isolation table disposed between the surface plate and the measuring unit, A wafer processing system comprising the above.

2. The grinding unit includes A grinding table on which the wafer is placed and which rotates the wafer, A grindstone that is relatively contacted with an end portion of the wafer placed on the grinding table to grind the end portion, and has The measuring unit includes A measuring table on which the wafer is placed and which rotates the wafer, A shape measuring device for measuring the shape of an end portion of the wafer placed on the measuring table, and has The wafer processing system according to Claim 1.

3. The measuring unit has A first sensor for measuring the diameter of the wafer and the center position of the wafer with respect to the measuring table, The surface plate has A second sensor for measuring the center position of the wafer with respect to the surface plate, Based on the difference between the two center positions measured by the first sensor and the second sensor, and the relative positions of the respective rotation centers of the measuring table and the grinding table set in advance, it has a control device for controlling the transfer amount of the wafer by the transfer unit, The wafer processing system according to Claim 2.

4. The measuring unit is provided with a shape measuring device, The shape measurement device includes an optical unit that is a white light interference microscope. The wafer processing system according to any one of claims 1 to 3.

5. The vibration isolation table is moved between a seating position that is a non-operating position and a floating position that is located above the seating position and is an operating position. It has a locking member that fixes the vibration isolation table in the floating position and releases the fixing. The wafer processing system according to any one of claims 1 to 3.

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