A dicing apparatus, which performs a cutting or groove-forming process on a workpiece such as a wafer on which semiconductor elements or electronic components are formed, includes at least: a rotary blade which is formed of a thin grindstone called a blade and is rotated by a spindle at high speed; a worktable which holds the workpiece; and X, Y, Z, and θ moving shafts which change a relative position between the worktable and the blade. At the time of processing the workpiece, a cutting fluid for cooling or lubrication is supplied from a nozzle to the rotating blade or a processing point at which the workpiece and the blade contact each other, and the cutting or groove-forming process is performed on the workpiece by the operations of the respective moving shafts.
FIG. 8 illustrates a conventional example of the dicing apparatus. A dicing apparatus 70 includes a processing part 75. The processing part has: high-frequency motor built-in type spindles 72, 72 respectively equipped with a blade 71 and a wheel cover (not shown) on their tips, and disposed so as to be opposed to each other; a worktable 73 which adsorbs and holds a workpiece W; and an image pickup device 74 formed of a microscope, a CCD camera, or the like for picking up an image of the workpiece W. In addition to these components, the dicing apparatus 70 includes: a cleaning part 76 which spin-cleans the processed workpiece W which has been processed by the processing part 75; a load port 77 onto which a cassette that houses a large number of the workpieces W mounted on a frame F is set; a conveyance device 78 which conveys the workpiece W; a controller 79 which controls the operations of the respective parts; and the like.
As illustrated in FIG. 9, the structure of the processing part 75 includes an X table 83 which is guided by X guides 81, 81 provided to an X base 80 and is driven by a linear motor 82 in an X direction indicated by X-X of the figure. A worktable 85 is provided to the X table 83 via a rotary table 84 which rotates in a θ direction.
On the other hand, Y tables 88, 88 which are guided by Y guides 87, 87 and are driven by a stepper motor (not shown) and a ball screw (not shown) in a Y direction indicated by Y-Y of the figure are provided on a side surface of a Y base 86. A Z table 89 which is driven by a drive device (not shown) in a Z direction indicated by Z-Z of the figure is provided to each of the Y tables 88. The high-frequency motor built-in type spindle 72 which has the blade 71 on its tip is fixed to the Z table 89. The processing part 75 has the structure as described above, and hence the blade 71 is step-fed (fed in a stepwise manner) in the Y direction and also is fed while cutting-in (cutting-in feed) in the Z direction, and the worktable 73 is fed while cutting (cutting feed) in the X direction.
The spindles 72 are both rotated at a high speed of 1,000 rpm to 80,000 rpm, and a supply nozzle (not shown) which supplies the cutting fluid into which the workpiece W is to be immersed is provided in the vicinity of the spindles 72.
An electrodeposition blade obtained by electrodepositing diamond abrasive grains or CBN abrasive grains with nickel, a metal-resin bonding blade obtained by bonding with a resin mixed with a metal power, or the like is used as the blade 71. The dimensions of the blade 71 are variously selected depending on the processing type. In a case where a general semiconductor wafer is diced into the workpiece, a blade having a diameter of approximately 50 mm and a thickness of approximately 30 μm is used.
In addition, the controller which controls the operations of the respective parts of the dicing apparatus 70 includes a CPU, a memory, an input/output circuit part, various control circuit parts, and the like, and is incorporated inside a pedestal of the dicing apparatus 70. As the dicing apparatus having the above-mentioned structure, for example, a dicing apparatus disclosed in Patent Document 1 has been proposed.
In the dicing apparatus 70 having the above-mentioned structure, as a stage prior to the processing, an alignment operation is performed, in which an image of the workpiece W is picked up by the image pickup device 74 and the position of the workpiece W is aligned with the blade 71. Also during the processing, if necessary, an image of the workpiece W is picked up by the image pickup device 74 as appropriate to check a processing condition. However, in the dicing apparatus 70, only one worktable 73 onto which the workpiece W is set and only one image pickup device 74 which picks up an image of the workpiece are provided. Therefore, during the processing of one workpiece W, it is not possible to set another new workpiece W onto the worktable 73 to perform the alignment by the image pickup device 74. Accordingly, the utilization rate of the image pickup device is low, and in addition, the utilization rate of the entire dicing apparatus is also deteriorated.
As a solution to such a problem, Patent Document 2 discloses a dicing apparatus in which two blades, two worktables, and two image pickup devices are provided. In this dicing apparatus, a workpiece which is set onto one worktable is aligned by one image pickup device, while a workpiece which is set onto another worktable is aligned by another image pickup device. Then, the workpiece which is set onto the one worktable is processed by one blade, while the workpiece which is set onto the another worktable is processed by another blade. Alternatively, the workpiece which is set onto the one worktable or the another worktable is processed by both the one blade and the another blade. In this manner, two workpieces are aligned individually by the two image pickup devices, and one workpiece is processed by the two blades, whereby the utilization rate of the dicing apparatus is improved.    Patent Document 1: Japanese Patent Application Laid-Open No. 2002-280328    Patent Document 2: Japanese Patent Application Laid-Open No. 2006-156809