High speed method of aligning cutting lines of a workplace using patterns

Abstract

Two imaging equipment are provided at a pair of cutting blade units, and the two imaging equipment image patterns at first positions in proximity to the center of a wafer at the same time. A controller drives drive mechanisms to align the wafer in such a way that current image patterns at the first positions can match with a reference pattern at the first positions. Then, the two imaging equipment are moved to positions for imaging patterns at second positions at the outer circumference of the wafer to image the patterns at the second positions. The controller drives the drive mecha- nisms to align the wafer in such a way that current image patterns at the second positions can match with a reference pattern at the second positions.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates generally to an alignment method and apparatus applied to a worktable of a semicon- ductor dicing machine, and more particularly to a wafer alignment method and apparatus of a dicing machine, which cuts a semiconductor wafer ( a workpiece) into squares with a pair of cutting blade units.[0003]2. Description of Related Art[0004]The processing speed of the dicing machine has become higher, whereas the diameter of the semiconductor wafer has become larger. To reduce the processing time, a cutting speed is raised, a return speed is raised, or an alignment speed is raised. Raising the cutting speed, however, may deteriorate the cutting performance, and raising the return speed excessively increases the vibrations of the dicing machine. Thus, raising the cutting speed and the return speed does not achieve dramatic results, and therefore, the best way is raising the alignment speed.[0005]FIG. 7 is...

AI Technical Summary

Benefits of technology

[0013]According to the present invention, the reference pattern at one point on the workpiece located at a preset position is registered in the storage means. Then, the patterns at two points in proximity to the center of the workpiece are imaged at the same time by the two imaging means which are provided at the pair of cutting blade units, and the control means drives the work mounting means so that the picked- up current image patterns at the two points can match with the reference pattern, thus aligning the workpiece. Next, either one of two imaging means is moved to a position to image a pattern at one point at the outer circumference of the workpiece. The control means drives the work mounting means so that the picked-up current image pattern at the point can match with the reference pattern, thus aligning the workpiece, and the alignment of the workpiece is completed. According to the present invention, the pair of cutting blade units are provided with the imaging means, and the two imaging means simultaneously image the patterns at two points in proximity to the center of the workpiece so as to align the workpiece. Compared with the conventional align- ment method in which the patterns are imaged on a point- by-point basis, the alignment can be performed at higher speed in a shorter period of time.

Problems solved by technology

Raising the cutting speed, however, may deteriorate the cutting performance, and raising the return speed excessively increases the vibrations of the dicing machine.

Thus, raising the cutting speed and the return speed does not achieve dramatic results, and therefore, the best way is raising the alignment speed.

The conventional wafer alignment method, however, has a problem in that the alignment cannot be performed at high speed since the patterns at the positions ①, ② and ③ must be imaged at three stages.

The conventional wafer alignment method has another problem in that it takes a long time to align the wafer since the camera must be moved in the direction X from the position ④ to ⑤ at CHI and the camera must be moved in the direction X from the position ⑥ to ⑦ at CH2.

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