San Jose, California
June 29, 2005

(San Jose, CA)—STM, Inc. has determined that purging the UV irradiation chamber with liquid Nitrogen provides excellent repeatability in curing the UV tape used for wafer dicing and subsequent pick-and-place processing. When used in conjunction with a clean backside surface and uniformly mounted wafer, the addition of Nitrogen also allows for delays that may occur between dicing and pick-and place without compromising the quality of the process.

The experiment involved a matrix that included wafers diced and picked the same day both with and without Nitrogen purging, and wafers diced, but picked 72 hours later with and without Nitrogen purging. The results clearly show that those wafers processed with Nitrogen had no residual tape residue, no matter the process time involved.

The explanation for these results is directly related to the displacement of Oxygen by the addition of Nitrogen. The reaction between the UV light and the Oxygen present in the atmosphere creates ozone, thus blocking the UV light from the adhesive surface. This makes it hard to predict the time necessary for complete curing of the tape, and could lead to problems when attempting to lift off the die at the next step.

As manufacturing levels increase, it is inevitable that backups will occur at some process steps. Having the flexibility to delay the pick-and-place process without affecting the quality of the die can be a vital benefit.

ABOUT STM, INC.
Semiconductor Tapes and Materials, Inc. provides consumable products for use by integrated circuit manufacturers. The STM product line includes UV and Non-UV backgrinding and dicing tapes, dicing blades, and diamond grining wheels. STM, Inc. is headquartered in San Jose, California.

For More Information Contact:
Laila H. Collins
Ph. (408) 451-2000 x101
lhaq@semiconductortapes.com