Pad Surface Preparation, Grooving, and QC

The Challenge

Thickness Non-Uniformity Our experience has shown that most as-received CMP pads exhibit gross local and global thickness uniformity issues. This non-uniformity, which may be as high as ±50 microns for a 1,500-micron-thick pad, can significantly affect within-wafer removal-rate uniformity, wafer-level defects, polisher vibration, and pad life.

Presence of a Skin Layer Most individually formed pads have a skin layer on their outer surface that forms during molding or pressing. Because of its distinct mechanical and textural properties, this skin layer significantly lengthens pad seasoning and break-in procedures, reducing throughput, shortening diamond disc life, and increasing your module’s overall cost of ownership.

Surface Preparation

Araca, Inc., is the exclusive agent of Toho in North America, Europe, and the Middle East. Using Toho’s patented pad surface preparation technology, we can efficiently remove the skin layer from your pad’s surface with controlled accuracy of 5 microns and processing precision of 15 microns. The amount of material that can be skinned may be as low as 50 microns or as high as 75 percent of the pad’s initial thickness. The skinning process may be performed on both top and bottom surfaces of the pad.

Accuracy and Precision 5 microns of controlled accuracy and 15 microns of processing precision

Flexible Material Removal From 50 microns up to 75% of the initial pad thickness. Both on the top and bottom surfaces

Precision Grooving

The same patented technology also allows us to precisely and efficiently groove the surface of most CMP pads (regardless of their bulk mechanical properties, although there may be some limitations). Grooves of virtually any design can be machined with a control accuracy of 5 microns and a processing precision of 15 microns, in all three dimensions (i.e., depth, width, and pitch).

Custom Groove Patterns

We also work with our clients to design, develop, and test customized groove patterns to achieve specific thermal, mechanical, tribological, kinetic, wafer-level defect, and fluid-dynamics goals during the CMP process. In the case of spiral and concentric patterns, the grooves can also be slanted by up to 40 degrees (as in a series of recent patents awarded to Toho Engineering) to achieve specific polishing objectives.

Dimensional QC Services

Our surface preparation and grooving processes are conducted at Toho’s world-class clean room facility in Mie, Japan. Within the same facility, we also provide dimensional QC services with 100% sampling, including surface roughness, groove width, depth, and pitch.