Laser segmented cutting, multi-step cutting, or both

Abstract

UV laser cutting throughput through silicon and like materials is improved by dividing a long cut path (112) into short segments (122), from about 10 μm to 1 mm. The laser output (32) is scanned within a first short segment (122) for a predetermined number of passes before being moved to and scanned within a second short segment (122) for a predetermined number of passes. The bite size, segment size (126), and segment overlap (136) can be manipulated to minimize the amount and type of trench backfill. Real-time monitoring is employed to reduce rescanning portions of the cut path 112(112) where the cut is already completed. Polarization direction of the laser output (32) is also correlated with the cutting direction to further enhance throughput. This technique can be employed to cut a variety of materials with a variety of different lasers and wavelengths. A multi-step process can optimize the laser processes for each individual layer.

Description

NOTICE[0001]More than one application for reissue of U.S. Pat. No. 6,676,878 has been filed. The reissue applications are U.S. patent application Ser. Nos. 12 / 351,562, (the present application), 12 / 350,767, 12 / 256,156, and 11 / 332,815, all of which are divisional applications for reissue of U.S. Pat. No. 6,676,878.RELATED APPLICATIONS[0002]This is an application for reissue of U.S. Pat. No. 6,676,878 and a division of U.S. patent application Ser. No. 11 / 332,815 filed Jan. 13, 2006, which is an application for reissue of U.S. Pat. No. 6,676,878.[0003]This patent applicationU.S. patent application Ser. No. 10 / 165,428, filed Jun. 6, 2002, on which U.S. Pat. No. 6,676,878 issued, derives priority from U.S. Provisional Application No. 60 / 297,218, filed Jun. 8, 2001, and is a CIP of U.S. patent application Ser. No. 10 / 017,497, filed Dec. 14, 2001, (now U.S. Pat. No. 7,157,038), which claims priority from U.S. Provisional Application No. 60 / 265,556, filed Jan. 31, 2001, and is a CIP of U.S....

AI Technical Summary

Benefits of technology

[0012]An object of the present invention is, therefore, to provide a method and / or system for improving the throughput for laser cutting silicon or other materials.

[0013]As a result, laser sawing is becoming an attractive alternative to these conventional techniques for dicing. Some reasons for the consideration of laser dicing would be that lasers can cut curved die such as Arrayed Waveguide Gratings (AWGs) from a wafer, unlike either of the two conventional techniques. In addition, lasers can often cut without the use of water, which is of great importance for the manufacture of devices which are water sensitive, such as MEMS. Dicing saws, which are today the predominant technique in use, typically require the use of water as a lubricant and / or coolant. Lasers also offer the potential of the smallest street width available, due to a potentially very small kerf width and the possibility of very accurate alignment of the laser to the workpiece (wafer).

Problems solved by technology

Skilled persons will also note that dicing blades tend to wear relatively quickly such that the widths of their cuts may vary over time.

In some cases, the blades can be inadvertently bent and then such blades produce curved or slanted cuts or increased chipping.

When the target material is thick, many passes (in some cases over 100 passes) may be necessary to complete the cutting process, particularly with limited laser power.

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