Processing apparatus and imaging method

Abstract

We propose a novel technology for real-time imaging of machined grooves during machining. [Solution] A processing apparatus comprising at least a holding table 8 for holding a wafer W which is a workpiece, a processing unit 20 for processing the wafer W held on the holding table 8, an imaging unit 40 for imaging the surface of the wafer W, and a control unit 10, wherein the processing apparatus is configured to include a first moving mechanism for moving the processing unit 20 and a second moving mechanism for moving the imaging unit 40.

Description

Technical Field

[0001] The present invention relates to a technique for imaging a processed surface of a workpiece such as a semiconductor wafer.

Background Art

[0002] Conventionally, for example, as disclosed in Patent Document 1, a technique for dividing a workpiece such as a semiconductor wafer into individual chips is known. In Patent Document 1, it is disclosed that processing is performed by so-called dicing using a cutting device (for example, see Patent Document 1).

[0003] Patent Document 1 discloses a technique in which a processing groove is formed along a division line by a cutting unit, which is a processing unit fixed to the tip of a spindle of a cutting device, and the workpiece is divided into individual chips. [[ID=]18]

[0004] When the workpiece is processed with a cutting blade of a cutting unit, chipping occurring at the edge portion of the surface of the chip and meandering of the processing groove will affect the processing quality of the chip.

[0005] Therefore, Patent Document 1 discloses a technique in which after processing, the processing groove is imaged with a microscope on the cutting device to confirm the state of the processing groove.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the configuration in Patent Document 1 involves stopping the machining process after processing and then imaging the machined groove, which hinders the improvement of throughput (productivity). Furthermore, since the condition of the machined groove cannot be checked until the entire machining process is complete, any machining defects that occur during the process cannot be recognized, which also hinders the improvement of yield.

[0008] Therefore, real-time imaging during processing is being considered, but since the surface of the workpiece being imaged is not stationary but moving, it is necessary to be able to focus more accurately.

[0009] In view of the above problems, the present invention proposes a novel technology for imaging a machined groove in real time during machining. [Means for solving the problem]

[0010] The problems that this invention aims to solve are as described above, and the means for solving these problems will now be explained.

[0011] According to one aspect of the present invention, a processing apparatus comprising at least a holding table for holding a workpiece, a processing unit for processing the workpiece held on the holding table, an imaging unit for imaging the surface of the workpiece, and a control unit, wherein the processing apparatus comprises a first moving mechanism for moving the processing unit and a second moving mechanism for moving the imaging unit.

[0012] Furthermore, according to one aspect of the present invention, the processing unit is configured to be movable in a direction intersecting the processing direction by the first moving mechanism, and the imaging unit is configured to be movable in a direction parallel to the direction of movement of the processing unit by the second moving mechanism.

[0013] Furthermore, according to one aspect of the present invention, the imaging unit is configured to allow adjustment of the distance from the surface of the workpiece by the second moving mechanism.

[0014] Furthermore, according to one aspect of the present invention, the imaging unit is positioned by the second moving mechanism to image the location of the processing groove formed by the processing unit, the processing groove is formed along a division line set at a predetermined index width interval, and the imaging unit either images the processing groove formed on a division line processed before the division line currently being processed, or images the processing groove formed on the division line currently being processed.

[0015] Furthermore, according to one aspect of the present invention, the imaging method comprises at least a holding step of holding the workpiece on the holding table, a processing step of processing the workpiece along a planned division line using the processing unit, and an imaging step of imaging the processed area of ​​the processed workpiece using the imaging unit, wherein the processing step and the imaging step are performed simultaneously.

[0016] Furthermore, according to one aspect of the present invention, the imaging unit images a machining groove formed on a division line that was processed before the division line currently being processed, or images a machining groove formed on the division line currently being processed. [Effects of the Invention]

[0017] The present invention provides the following effects: In other words, according to one aspect of the present invention, the condition of the processed groove can be checked in real time (kerf check) simultaneously with processing. By stopping the processing according to the condition of the processed groove, defects can be identified and corrected, thereby improving the yield of wafer processing.

[0018] Furthermore, according to one aspect of the present invention, the second movement mechanism (Z-axis movement mechanism) can be driven to focus the imaging unit during imaging, so that a more focused and clearer image can be obtained even when the surface of the workpiece being imaged is not stationary but moving. [Brief explanation of the drawing]

[0019] [Figure 1] It is a perspective view of an embodiment of a cutting device used in the implementation of the present invention. [Figure 2] It is a diagram for explaining the configuration of a processing unit and the like. [Figure 3] It is a diagram for explaining a Z-axis movement mechanism and a Y-axis movement mechanism. [Figure 4] It is a diagram for explaining the configuration of an imaging unit and the like. [Figure 5] It is a diagram showing an example of an imaged image. [Figure 6] (A) It is a diagram for explaining an example of a processing step. (B) It is a diagram for explaining an example of a processing step. [Figure 7] (A) It is a diagram for explaining an example of a processing step. (B) It is a diagram for explaining an example of a processing step. [Figure 8] It is a diagram for explaining an embodiment in a dual dicer.

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the configuration of a cutting device 2 which is an embodiment of a processing device according to the present invention. In the following figures, explanations will be made based on the directions of the X-axis, Y-axis, and Z-axis shown in FIG. 1.

[0021] The cutting device 2 has a base 4, and a holding table 8 is disposed on the base 4 so as to be reciprocable in the X-axis direction by a cutting feed mechanism (X-axis movement mechanism) not shown in the figure.

[0022] The upper surface of the base 4 is provided with a cassette mounting section 5a for mounting a cassette 5 containing the workpiece wafer W, and a cleaning device 6 for cleaning the wafer W after cutting. Devices are arranged regularly on the surface of the wafer W, and grid-like division lines are set between the devices. By cutting along the division lines, the wafer is expected to be broken down into individual chips. Note that devices may not be formed on the surface of the wafer W.

[0023] The wafer W is integrated with the annular frame F via tape T to form a frame unit U. The frame unit U is housed in a cassette 5 and transported onto a holding table 8 by a transport device (not shown). As will be described in detail later, the wafer W is cut in a processing unit 20 (cutting unit), then transported to a cleaning device 6 for cleaning, and after cleaning, it is transported back to the cassette 5.

[0024] Multiple clamps 9 and a water cover 11 are arranged around the holding table 8, and a bellows 12 is connected between the water cover 11 and the base 4 to protect the cutting feed mechanism located below.

[0025] A gate-shaped column 14 is erected on the base 4. On the side of the column 14 are a pair of guide rails 15 extending in the Y-axis direction, a Y-axis movement mechanism 17 consisting of a ball screw 16a and a pulse motor 16b, and a Y-axis movement block 18. The Y-axis movement block 18 moves in the Y-axis direction along the guide rails 15 by the drive of the Y-axis movement mechanism 17.

[0026] The Y-axis movement block 18 is provided with a pair of guide rails 19 extending in the Z-axis direction, a Z-axis movement mechanism 32 consisting of a ball screw 31a and a pulse motor 31b, and a Z-axis movement block 30. The Z-axis movement block 30 moves in the Z-axis direction along the guide rails 19 by the drive of the Z-axis movement mechanism 32.

[0027] A machining unit 20 is installed in the Z-axis movement block 30. The machining unit 20 has a spindle driven by a motor (not shown), and a cutting blade 21 is attached to the tip of the spindle.

[0028] An imaging unit 40 is positioned near the processing unit 20 to image the surface of the wafer W processed by the processing unit 20. The imaging unit 40 is supported by a Z-axis movement block 30 via a Z-axis movement mechanism 61 and a Y-axis movement mechanism 62, and is configured to allow positional adjustment of the imaging unit 40 in both the Z-axis and Y-axis directions. The imaging unit 40 may image the surface of the wafer W and perform alignment between the processing unit 20 and the planned division line, or imaging for alignment may be performed by a device separate from the imaging unit 40.

[0029] The cutting device 2 is equipped with a control unit 10, which automatically controls each drive unit. Specifically, the control unit 10 controls the process from cutting the wafer W along the grid-like division lines using the processing unit 20, dividing the wafer W into chips, to cleaning in the cleaning device 6.

[0030] Figures 2 and 3 show the arrangement and configuration of the processing unit 20 and the imaging unit 40. As shown in Figure 2, the machining unit 20 is comprised of a cutting blade 21, a spindle 22, a shower nozzle block 23, and a cutting fluid supply nozzle assembly 24.

[0031] The cutting blade 21 is constructed with a disc-shaped cutting edge, which is formed to a predetermined thickness from abrasive grains such as diamond or CBN (Cubic Boron Nitride) and a bonding material (binder) such as metal or resin.

[0032] The spindle 22 is rotationally driven by a motor (not shown), and the cutting blade 21 is fixed to the tip of the spindle 22.

[0033] The shower nozzle block 23 is configured to have a shower nozzle 23a for supplying cutting fluid toward the outer edge of the cutting blade 21 and cooling the cutting blade 21. Cutting fluid is supplied to the shower nozzle block 23 from a cutting fluid supply source (not shown) via a hose 23b.

[0034] The cutting fluid supply nozzle assembly 24 is configured to have a pair of cutting fluid supply nozzles 24a that supply cutting fluid from the sides toward the lower end portion of the cutting blade 21, thereby cooling the cutting blade 21. The cutting fluid supply nozzles 24a are positioned on both sides of the cutting blade 21 in the Y-axis direction, flanking the cutting blade 21. The cutting fluid supply nozzle assembly 24 is supplied with cutting fluid from a cutting fluid supply source (not shown) via a hose 24b.

[0035] The cutting fluid supplied from the shower nozzle 23a and the cutting fluid supply nozzle 24a may be the same or different. The cutting fluid may be, for example, pure water.

[0036] An imaging unit 40 is positioned upstream of the processing unit 20 in the X-axis direction (processing direction), that is, upstream in the processing feed direction X1 of the wafer W.

[0037] As shown in Figures 2 to 4, the imaging unit 40 is comprised of a housing 41, an optical system 42, a light source 43a, a fiber head 43b, a microscope 44a, a camera 44b, and an objective lens 45.

[0038] As shown in Figure 4, the optical system 42 is housed within the housing 41 and comprises a mirror 42a for changing the direction of light supplied from the light source 43a and emitted from the fiber head 43b by 90 degrees toward the surface of the wafer W, and a half-mirror 42b for changing the direction of reflected light from the wafer W by 90 degrees and directing it into the microscope 44a. An objective lens 45 is positioned between the half-mirror 42b and the wafer W, and the light image incident from the objective lens 45 is formed by the camera 44b through the microscope 44a, and an image is formed by a driver (not shown). The light source 43a may be provided inside the housing 41, or it may be provided outside the housing 41b.

[0039] Figure 5 shows an example of an image G captured by camera 44b, illustrating the formation of a processing groove Wm on the surface Wa of the wafer W.

[0040] As shown in Figure 3, the housing 41 of the imaging unit 40 is supported by the Z-axis movement block 30 via the Z-axis movement mechanism 61 and the Y-axis movement mechanism 62.

[0041] Specifically, the housing 41 of the imaging unit 40 is fixed to the case 61a of the Z-axis movement mechanism 61 via a bracket 64a. Inside the case 61a of the Z-axis movement mechanism 61, there is a Z-axis drive unit 61b for relative movement of the case 61a in the Z-axis direction with respect to the Y-direction movement arm 62a. By moving the case 61a in the Z-axis direction, the imaging unit 40 is moved in the Z-axis direction. This makes it possible to adjust the distance between the imaging unit 40 and the surface Wa of the wafer W.

[0042] The Y-axis movement mechanism 62 has a Y-axis drive unit 62b for moving the Y-direction movement arm 62a in the Y-axis direction. By moving the Y-direction movement arm 62a, the case 61a of the Z-axis movement mechanism 61 is moved in the Y-axis direction, thereby moving the imaging unit 40 in the Y-axis direction.

[0043] The Y-axis movement mechanism 62 is supported by the Z-axis movement block 30 via brackets 64b and 64c. Bracket 64c has a through groove 64d formed in the Y-axis direction, through which the Y-direction movement arm 62a passes vertically, and which allows movement in the Y-axis direction.

[0044] As described above, as shown in Figures 1 to 4, a processing apparatus is configured that includes at least a holding table 8 for holding a wafer W which is a workpiece, a processing unit 20 for processing the wafer W held on the holding table 8, an imaging unit 40 for imaging the surface of the wafer W, and a control unit 10, wherein the processing apparatus is configured to include a first moving mechanism for moving the processing unit 20 and a second moving mechanism for moving the imaging unit 40. In the example in Figure 1, the first moving mechanism for moving the processing unit 20 is configured to include a Y-axis moving mechanism 17 and a Z-axis moving mechanism 32. In the example in Figure 3, the second moving mechanism for moving the imaging unit 40 is configured to include a Z-axis moving mechanism 61 and a Y-axis moving mechanism 62.

[0045] Furthermore, with the above configuration, as shown in Figures 1 to 4, the processing unit 20 is configured to be movable in the Y-axis direction intersecting the processing direction (X-axis direction) by a first moving mechanism, and the imaging unit 40 is configured to be movable in the Y-axis direction parallel to the movement direction (Y-axis direction) of the processing unit 20 by a second moving mechanism.

[0046] Furthermore, with the above configuration, as shown in Figures 1 to 4, the imaging unit 40 is configured to be able to adjust its distance from the surface Wa of the wafer W by the second movement mechanism.

[0047] Next, a method for imaging the processed grooves on the surface of the wafer in the above configuration will be described. As shown in Figure 1, first, a holding step is performed in which the wafer W, which is the workpiece, is held on the holding table 8. Specifically, the annular frame unit U is removed from the cassette 5, placed on the holding table 8, and the annular frame F is clamped with the clamp 9.

[0048] Next, as shown in Figures 2 and 3, a processing step is performed in which the wafer W is processed by the processing unit 20. Specifically, after alignment, the cutting blade 21 of the processing unit 20 is positioned at a predetermined height and rotated at high speed, and the wafer W is fed in the X-axis direction (processing feed direction X1) to form a processing groove Wm on the surface Wa of the wafer W along the planned division line. After processing for a planned division line, the processing unit 20 is indexed and fed in the Y-axis direction by the Y-axis movement block 18 (Figure 1), and processing is performed for the next adjacent planned division line. Each planned division line is set at an interval of a predetermined index width.

[0049] During the machining step, cutting fluid is supplied to the cutting blade 21 from the shower nozzle 23a and the cutting fluid supply nozzle 24a shown in Figure 2.

[0050] As shown in Figure 6(A), in parallel with the processing step, an imaging step is performed in which the imaging unit 40 images the surface Wa of the wafer W from above.

[0051] In the example shown in Figure 6(A), imaging is performed on the machining groove Wm formed on the division line S-1, which was machined immediately before the division line S currently being machined. In this case, the control unit 10 (Figure 1) drives the Y-axis movement mechanism 62 (Figure 3) to align the Y-axis position of the imaging unit 40 (objective lens 45 (Figure 4)) with the division line S-1, and drives the Z-axis movement mechanism 61 (Figure 3) to focus, thereby acquiring an image G including the machining groove Wm, as shown in Figure 5.

[0052] In this way, an image G including the processed groove Wm can be acquired in parallel with the processing step, and the state of the processed groove Wm can be checked in real time (kerf check) simultaneously with processing. Then, by stopping the processing according to the state of the processed groove Wm, defects can be identified and corrected, and the yield of wafer processing can be improved.

[0053] Furthermore, by driving the second movement mechanism (Z-axis movement mechanism 61 (Figure 3)), the imaging unit 40 can be focused during imaging. This allows for the acquisition of a more focused and clearer image G even when the surface of the workpiece being imaged is not stationary but moving.

[0054] In the example shown in Figure 6(B), imaging is performed on the machining groove Wm formed on the division line S-2, which was machined two division lines prior to the division line S currently being machined. Since the imaging unit 40 can set its position in the Y-axis direction independently of the machining unit 20, it is possible to obtain an image of the desired division line. For example, in situations where imaging is difficult due to the influence of cutting fluid because the imaging unit 40 is too close to the machining unit 20, it is possible to deliberately image a machining groove Wm at a position far from the machining unit 20.

[0055] In the example shown in Figure 7(A), the imaging unit 40 is positioned downstream of the processing unit 20 in the X-axis direction (processing direction), that is, downstream of the processing unit 20 in the processing feed direction X1 of the wafer W. In this case, in Figure 3, for example, the Z-axis moving mechanism 61 and the Y-axis moving mechanism 62 are positioned so that the imaging unit 40 is located behind the Z-axis moving block 30. According to this example, it becomes possible to image the processing groove Wm immediately after it is formed on the dividing line currently being processed by the processing unit 20, enabling real-time checking (kerf checking).

[0056] Figure 7(B) shows an example where processing is performed sequentially from the leftmost division line in the figure. As shown, the imaging unit 40 can set its position in the Y-axis direction independently of the processing unit 20, so it can handle both processing from the left and processing from the right, as shown in Figures 6(A) and 6(B).

[0057] Furthermore, as shown in the example in Figure 8, for example, the present invention can also be implemented in a processing apparatus that constitutes a so-called dual dicer by having two processing units 20A and 20B.

[0058] Furthermore, although the above embodiments have described an example of a processing apparatus equipped with a cutting blade 21 (Figure 3) as a processing unit, the processing unit may also be a laser processing unit that forms processing grooves by laser ablation. The present invention makes it possible to check (kerf check) the processing grooves formed by laser ablation in real time. [Explanation of Symbols]

[0059] 2 Cutting equipment 8. Holding Table 10 Control Unit 20 processing units 21 Cutting blades 30 Z-axis movement block 40 Imaging Units 61 Z-axis movement mechanism 62 Y-axis movement mechanism F Circular Frame G imaging S division planned line W wafer Wm Machining groove X1 Machining feed direction

Claims

1. A holding table for holding the workpiece, A processing unit for processing the workpiece held on the holding table, An imaging unit for imaging the surface of the workpiece, A processing apparatus comprising at least a control unit, A first moving mechanism for moving the processing unit, A second moving mechanism for moving the imaging unit, A processing device equipped with the following features.

2. The processing unit is configured to be movable in a direction intersecting the processing direction by the first moving mechanism, The imaging unit is configured to be movable in a direction parallel to the movement direction of the processing unit by the second moving mechanism. The processing apparatus according to feature 1.

3. The imaging unit is configured to allow adjustment of the distance to the surface of the workpiece by the second moving mechanism. The processing apparatus according to feature 2.

4. The imaging unit is positioned by the second moving mechanism to image the location of the processed groove formed by the processing unit. The processed groove is formed along a division line set at a predetermined index width interval, The imaging unit is, Image the machined grooves formed on the division line that was processed before the division line currently being processed. Or, Image the machining grooves formed in the division line currently to be processed. The processing apparatus according to claim 1 or 2.

5. An imaging method for imaging a workpiece in a processing apparatus according to any one of claims 1 to 3, A holding step of holding the workpiece on the holding table, A processing step of processing the workpiece along the planned division line using the processing unit, An imaging step in which the processed area of ​​the processed workpiece is imaged by the imaging unit, It includes at least, The processing step and the imaging step are performed simultaneously. An imaging method characterized by the following:

6. The imaging unit is, Image the machined grooves formed on the division line that was processed before the division line currently being processed. Or, Image the machining grooves formed in the division line currently to be processed. The imaging method according to feature 5.

Images