Processing apparatus and imaging method

Abstract

We propose a novel technology for real-time imaging of machining grooves near the machining area. [Solution] 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 imaging unit comprises a housing, a microscope provided inside the housing, a light source, a fluid supply port for supplying and filling the gap between the housing and the workpiece with fluid, and an intrusion prevention fluid supply port for discharging an intrusion prevention fluid to prevent foreign matter from entering the gap between the housing and the workpiece.

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, as disclosed in Patent Document 1 for example, 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 (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a technique of forming a processing groove along a division planned line by a cutting unit which is a processing unit fixed to the tip of a spindle of a cutting device, and dividing it into individual chips.

[0004] When a workpiece is processed with a cutting blade of a cutting unit, chipping generated at the edge portion of the surface of the chip and meandering of the processing groove will affect the processing quality of the chip. However, inspection of the processing quality of the chip after processing cannot be performed unless the workpiece is processed, so there is a problem of poor yield.

[0005] Therefore, in Patent Document 1, an imaging unit is disposed on the downstream side (opposite to the moving direction) with respect to the moving direction of the processing unit of the cutting device so that the processing groove immediately after processing can be imaged in real time.

[0006] In the configuration disclosed in Patent Document 1, imaging is performed in a state where a liquid is supplied between the workpiece and the imaging unit. This is for the purpose of preventing contamination from adhering to the surface of the workpiece, preventing drying of the surface, and preventing the cutting fluid supplied to the cutting blade from scattering to the downstream side and affecting imaging.

[0007] Also, in the configuration disclosed in Patent Document 1, a partition plate is provided between the processing unit and the imaging unit in order to prevent scattering of the cutting fluid. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2008-262983 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, even when a partition plate like the one in Patent Document 1 is provided, the scattering of cutting fluid is significant, and there is concern that the cutting fluid may enter the imaging area as foreign matter through the gap between the partition plate and the workpiece. In other words, simply providing a partition plate is insufficient, and there is a problem that the cutting fluid may adversely affect imaging.

[0010] On the other hand, in addition to dicing by forming grooves using a cutting blade, there is also laser dicing, which involves forming grooves using laser ablation. In this laser dicing process as well, there is a need to image the grooves in real time.

[0011] Although cutting fluid is not used in this laser dicing process, the debris generated by laser ablation can scatter as foreign matter or remain on the surface of the workpiece, potentially negatively impacting imaging. This is another challenge.

[0012] In view of the above problems, the present invention proposes a novel technology for imaging machined grooves in real time near the machined area. This proposes a novel configuration. [Means for solving the problem]

[0013] The problems that this invention aims to solve are as described above, and the means for solving these problems will now be explained.

[0014] 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 imaging unit comprises a microscope, a light source, a fluid supply port for supplying and filling a gap between the imaging unit and the workpiece with fluid, and an intrusion prevention fluid supply port for discharging an intrusion prevention fluid to prevent foreign matter from entering the gap between the imaging unit and the workpiece.

[0015] Furthermore, according to one aspect of the present invention, the imaging unit is arranged downstream of the processing unit in the processing direction and images the surface of the workpiece immediately after it has been formed by the processing unit.

[0016] Furthermore, according to one aspect of the present invention, the ingress prevention fluid supply port is formed on the processing unit side relative to the fluid supply port, and the ingress prevention fluid flows out toward the processing unit side.

[0017] Furthermore, according to one aspect of the present invention, the fluid supply port for preventing ingress is configured to be a wide slit shape that is long in a direction perpendicular to the processing direction in the horizontal plane, or to be formed at multiple locations at predetermined intervals in a direction perpendicular to the processing direction in the horizontal plane.

[0018] Furthermore, according to one aspect of the present invention, an imaging method for imaging the surface of a workpiece comprises at least a holding step of holding the workpiece on a holding table, and an imaging step of imaging the surface of the workpiece from above using an imaging unit, wherein the imaging unit comprises a microscope, a light source, a fluid supply port for supplying and filling a gap between the imaging unit and the workpiece with fluid, and an intrusion prevention fluid supply port for discharging an intrusion prevention fluid to prevent foreign matter from entering the gap between the imaging unit and the workpiece, and the imaging step involves supplying and filling the gap between the imaging unit and the surface of the workpiece from the fluid supply port, and imaging while discharging an intrusion prevention fluid from the intrusion prevention fluid supply port. [Effects of the Invention]

[0019] The present invention has the following effects. That is, according to one aspect of the present invention, the adverse effect on imaging caused by foreign matter generated in the processing unit is prevented, and it becomes possible to image the processing groove in real time near the processing location.

Brief Description of the Drawings

[0020] [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 front view for explaining the configuration of the cutting unit and the like. [Figure 3] It is a cross-sectional view for explaining the configuration of the imaging unit. [Figure 4] It is a side view for explaining the configuration of the imaging unit and the like. [Figure 5] It is a diagram showing an example of an imaging image. [Figure 6] It is a diagram for explaining the state of processing steps and the like by the cutting unit. [Figure 7] It is a diagram for explaining an example of an imaging step by the imaging unit. [Figure 8] It is a diagram for explaining the state of processing steps and the like by the laser processing unit. [Figure 9] It is a diagram for explaining another example of an imaging step by the imaging unit.

Modes for Carrying Out the Invention

[0021] 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 according to an embodiment of 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.

[0022] The cutting device 2 has a base 4, on which a holding table 8 is mounted so as to be able to reciprocate in the X-axis direction by a cutting feed mechanism (X-axis movement mechanism) not shown.

[0023] 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.

[0024] The wafer W is integrated with the annular frame F via tape T to form a wafer unit U. The wafer unit U is housed in a cassette 5 and transported onto a holding table 8 by a transport device (not shown). After being cut by a cutting unit 20, which is a processing unit, as will be described in detail later, it is transported to a cleaning device 6 for cleaning, and after cleaning it is returned to the cassette 5.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] A cutting unit 20, which serves as a processing unit, is installed in the Z-axis movement block 30. Inside the spindle housing 36 of the cutting unit 20, a spindle driven by a motor (not shown) is rotatably housed, and a cutting blade 21 is attached to the tip of the spindle. Near the cutting unit 20, an imaging unit 7 is installed for imaging the surface of the wafer W and performing alignment.

[0029] Near the cutting unit 20, an imaging unit 40 is provided for imaging the surface of the wafer W processed by the cutting unit 20. In this embodiment, the imaging unit 40 is fixed to the Z-axis moving block 30 via a Z-axis moving mechanism 60, and the Z-axis moving mechanism 60 is configured to adjust the position of the imaging unit 40 in the vertical direction (Z-axis direction). Mechanisms for adjusting the position of the imaging unit 40 in the X-axis direction or Y-axis direction may also be provided.

[0030] The cutting device 2 is equipped with a control unit 10, which automatically controls each drive unit. Specifically, the control unit 10 controls the cutting unit 20 to cut the wafer W along the grid-like division lines, divide the wafer W into chips, and then performs a series of controls up to cleaning in the cleaning device 6.

[0031] Figure 2 shows the arrangement of the cutting unit 20 and the imaging unit 40. The cutting unit 20 comprises a cutting blade 21, a spindle 22, a shower nozzle block 23, and a cutting fluid supply nozzle assembly 24.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] An imaging unit 40 is provided downstream of the cutting unit 20 in the X-axis direction (machining direction), that is, at a position where the machined groove newly formed by the cutting unit 20 is imaged. This makes it possible to image the surface Wa of the wafer W immediately after it is formed by the cutting unit 20.

[0038] 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.

[0039] 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).

[0040] 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.

[0041] As shown in Figure 4, the housing 41 of the imaging unit 40 is configured to include a first housing 41a that houses the optical system 42, and a second housing 41b that houses the fiber head 43b, microscope 44a, and camera 44b. The light source 43a is provided outside the second housing 41b, or it may be provided outside the second housing 41b.

[0042] The second housing 41b is supported by the Z-axis movement block 30 via the Z-axis movement mechanism 60. The Z-axis movement mechanism 60 is provided with a drive unit 62 for moving the second housing 41b up and down, and the drive unit 62 is driven and controlled by the control unit 10, thereby adjusting the overall height position (Z-direction position) of the imaging unit 40.

[0043] As shown in Figure 3, the first housing 41a has fluid supply ports 41c and 41d for supplying and filling the gap between it and the surface Wa of the wafer W.

[0044] In this embodiment, the first housing 41a is made of a metal block such as aluminum, and two fluid paths 41e and 41f are formed inside the first housing 41a for circulating fluid, and fluid supply ports 41c and 41d are formed at the openings of each fluid path 41e and 41f to the outside. The fluid paths 41e and 41f are connected to a fluid supply source 41k via a hose 41h and a valve 41v, and the supply and cessation of fluid is controlled by the control unit 10 controlling the valve 41v.

[0045] The fluid supply ports 41c and 41d are positioned on both sides of the objective lens 45 in the X-axis direction (machining direction), and the fluid is directed downwards around the objective lens 45. The shape, number, and arrangement of the fluid supply ports 41c and 41d are not particularly limited; for example, the fluid supply ports 41c and 41d may each be semi-circular in shape, or they may be connected to form an annular supply port overall.

[0046] The fluid discharged from the fluid supply ports 41c and 41d is a liquid, a gas, or a mixture of liquid and gas, and is selected as appropriate depending on the processing method, as will be described in more detail later.

[0047] As shown in Figure 3, the first housing 41a has an intrusion prevention fluid supply port 41m through which an intrusion prevention fluid is discharged to prevent foreign matter from entering the gap between the housing 41a and the surface Wa of the wafer W.

[0048] In this embodiment, the first housing 41a is made of a metal block such as aluminum, and a fluid path 41n for circulating fluid is formed inside the first housing 41a, and an ingress prevention fluid supply port 41m is formed at the opening of the fluid path 41n to the outside. The fluid path 41n is connected to a fluid supply source 41x via a hose 41p and a valve 41w, and the supply and cessation of fluid is controlled by the control unit 10 controlling the valve 41w.

[0049] The fluid ingress prevention port 41m is formed upstream of the objective lens 45 and the fluid ingress port 41c, that is, closer to the cutting unit 20, and is also formed so that the fluid flowing out from the fluid ingress prevention port 41m flows upstream in the X-axis direction (machining direction).

[0050] The shape, number, and arrangement of the fluid ingress prevention ports 41m are not particularly limited, but for example, the fluid ingress prevention ports 41m can be a wide slit shape that is long in the Y-axis direction (index feed direction) perpendicular to the processing direction (X-axis direction) in the horizontal plane, or multiple ports can be formed at predetermined intervals. This makes it possible to make the width Y1 of the fluid flowing out from the fluid ingress prevention ports 41m wider than the objective lens 45, as shown in Figure 4, for example, and effectively prevent foreign matter from entering the gap S between the objective lens 45 (first housing 41a of the imaging unit 40) and the surface Wa of the wafer W. Note that the fluid ingress prevention ports 41m can be formed in one or multiple locations.

[0051] The fluid discharged from the ingress prevention fluid supply port 41m is a liquid, a gas, or a mixture of liquid and gas, and is selected as appropriate depending on the processing method, as will be described in more detail later.

[0052] 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 6, first, a holding step is performed in which the wafer W, which is the workpiece, is held on the holding table 8.

[0053] Next, as shown in Figure 6, a processing step is performed in which the wafer W is processed by the cutting unit 20. Specifically, after alignment, the cutting blade 21 of the cutting unit 20 is positioned at a predetermined height and rotated at high speed, and the holding table 8 is fed in the X-axis direction, thereby continuously cutting the wafer W along the planned division line to form processing grooves.

[0054] 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.

[0055] As shown in Figures 6 and 7, an imaging step is performed in parallel with the processing step, in which the imaging unit 40 images the surface of the wafer W from above.

[0056] In this process, as shown in Figure 7, fluid R1 is supplied from the fluid supply ports 41c and 41d to fill the gap S between the objective lens 45 of the imaging unit 40 and the surface Wa of the wafer W. As the fluid R1, for example, pure water can be used, or high-pressure air can be used. This makes it possible to perform imaging while preventing foreign matter from adhering to the surface Wa of the wafer W.

[0057] During the machining and imaging steps, splashes 81 of the cutting fluid supplied to the cutting blade 21 and cutting debris 82 generated by cutting become foreign matter and scatter toward the imaging unit 40 downstream of the cutting unit (cutting blade 21). However, the entry of this foreign matter into the gap S is prevented by the entry prevention fluid R2.

[0058] Specifically, as shown in Figure 7, imaging is performed while the intrusion prevention fluid R2 is discharged from the intrusion prevention fluid supply port 41m. The intrusion prevention fluid supply port 41m is formed so that the discharged intrusion prevention fluid R2 flows upstream, that is, towards the cutting blade 21. By sealing the gap S with the intrusion prevention fluid R2 and allowing it to flow upstream, it is possible to prevent foreign matter such as splashes 81 of cutting fluid flying from the cutting blade 21 and cutting debris 82 generated by cutting from flowing into the gap S.

[0059] As the ingress prevention fluid R2, for example, pure water can be used, or high-pressure air can be used.

[0060] Figure 8 shows an example in which a laser processing unit 90 is used as the processing unit. The laser processing unit 90 performs laser ablation processing (laser dicing) by irradiating the wafer W with a laser beam 92 to form processing grooves.

[0061] As shown in Figure 9, during laser ablation processing, debris 84 (processing waste) is scattered as foreign matter, but the entry of this debris 84 into the gap S is prevented by an entry prevention fluid R4. This entry prevention fluid R4 is, for example, high-pressure air. In addition, fluid R3 is supplied from fluid supply ports 41c and 41d to fill the gap S between the objective lens 45 of the imaging unit 40 and the surface Wa of the wafer W, and this fluid R3 is also high-pressure air.

[0062] In typical laser ablation processes, the surface Wa of the wafer W is protected by a water-soluble resin, preventing damage to the surface Wa from direct adhesion of foreign matter. Therefore, it is preferable to use air as the fluid R3 or the intrusion prevention fluid R4 so as not to wash away this water-soluble resin.

[0063] As described above, according to the present invention, adverse effects on imaging by foreign matter generated in processing units such as the cutting unit 20 (Figure 6) and the laser processing unit 90 (Figure 8) are prevented, and it becomes possible to image the processed groove in real time near the processing area. [Explanation of Symbols]

[0064] 2 Cutting equipment 7 Imaging Unit 8. Holding Table 9 clamps 10 Control Unit 20 cutting units 21 Cutting blades 23a Shower nozzle 24a Cutting fluid supply nozzle 30 Z-axis movement block 40 Imaging Units 41 cabinets 41a First enclosure 41b Second cabinet 41c Fluid supply port 41d Fluid supply port 41e Fluid path 41f Fluid path 41k Fluid Source 41m Intrusion prevention fluid supply port 41n fluid path 41V bulb 41W bulb 41x Fluid Source 42 Optical system 42a Miller 42b Half Mirror 43a light source 43b Fiber head 44a Microscope 44b Camera 45 Objective lens 60 Z-axis movement mechanism 62 Drive unit 81. Droplets 82 Cutting waste 90 Laser Processing Unit G imaging R1 Fluid R2 Ingress prevention fluid S Gap W wafer Wa surface Wm Machining groove Y1 width

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, The imaging unit is, A microscope and, Light source and A fluid supply port for supplying and filling the gap between the workpiece and the device, An intrusion prevention fluid supply port for discharging an intrusion prevention fluid to prevent foreign matter from entering the gap between the workpiece and the device, A processing device equipped with the following features.

2. The imaging unit is positioned downstream of the processing unit in the processing direction. The surface of the workpiece immediately after it has been formed by the processing unit is imaged. The processing apparatus according to claim 1, characterized in that it is a processing apparatus.

3. The fluid supply port for preventing entry is formed on the processing unit side relative to the fluid supply port. The ingress prevention fluid is discharged toward the processing unit. The processing apparatus according to feature 2.

4. The ingress prevention fluid supply port is, The slit shape is long and wide in the direction perpendicular to the machining direction within the horizontal plane. or The configuration is such that multiple points are formed in a horizontal plane at predetermined intervals in a direction perpendicular to the processing direction. The processing apparatus according to feature 3.

5. An imaging method for imaging the surface of a workpiece, A holding step in which the workpiece is held by a holding table, The process includes at least an imaging step of imaging the surface of the workpiece from above using an imaging unit, The imaging unit is, A microscope and, Light source and A fluid supply port for supplying and filling the gap between the workpiece and the device, It comprises an intrusion prevention fluid supply port for discharging an intrusion prevention fluid to prevent foreign matter from entering the gap between the workpiece and the device, In the imaging step, Fluid is supplied from the fluid supply port to fill the gap between the imaging unit and the surface of the workpiece, The image is taken while the intrusion prevention fluid is discharged from the intrusion prevention fluid supply port. Imaging method.

6. The imaging unit is positioned downstream of the processing unit in the processing direction. The surface of the workpiece immediately after it has been formed by the processing unit is imaged. The imaging method according to claim 5, characterized by the features described herein.

7. The fluid supply port for preventing entry is formed on the processing unit side relative to the fluid supply port. The ingress prevention fluid is discharged toward the processing unit. The imaging method according to feature 6.

8. The ingress prevention fluid supply port is, The slit shape is long and wide in the direction perpendicular to the machining direction within the horizontal plane. or The configuration is such that multiple points are formed in a horizontal plane at predetermined intervals in a direction perpendicular to the processing direction. The imaging method according to feature 7.

Images