Campus News - January 14, 2002

UNM plans NASA flight at Johnson Space Center

By Michael Padilla

After winning a national competition, students from the UNM Department of Chemical and Nuclear Engineering will fly an experiment as part of the NASA Reduced Gravity Student Flight Opportunities Program on board the microgravity KC-135 airplane at Johnson Space Center March 7.

This is the second year in a row the department has won this national competition allowing the students to investigate the effect of weightlessness on spin-coating of computer wafers. The members of UNM, “S.P.I.N. Doctors” (Study of Photoresist in New Mexico) team, will fly on two consecutive days, two members each day for two hours.

“This is indeed great national recognition for UNM and a great opportunity and hands-on experience for our students,” said Mohamed El-Genk, faculty advisor for the project.

Spin-coating a photoresist polymer over a silicon substrate is traditionally one of the first steps in the manufacture of microprocessors in the semiconductor industry. This process is also widely employed in a number of other applications, including flat-screen display coatings, compact disks and television tube phosphor coatings. El-Genk said spin-coating is a fairly simple procedure involving minimal equipment and time.

The overall objectives of the experiment are to determine what role gravity plays in the spin-coating process and to ascertain whether or not spin-coating represents a viable method to coat a substrate with a thin, uniform film of material in a zero-gravity environment.

El-Genk said the procedure on board of the KC-135 airplane represents a fascinating, though somewhat complicated, fluid dynamics problem.

“Through the proposed experimentation, we hope to quantify the role gravity plays in the process, as well as determine if spin-coating may someday be feasible in a space environment,” El-Genk said.

The experiment will be carried out similarly to last year’s experiment. A modified spin-coater will be adapted for operation aboard the plane. The experiment will require two operators: one to store prepared wafers and place a clean wafer into the instrument, the other to change the parameters on the instrument control panel. Upon return to the lab, the photoresist films of each wafer prepared aboard the KC-135 will be profiled. This will help determine the overall thickness of the photoresist film, as well as the characteristics of the film at the edge of the wafer.

The specific objectives of the experiments are to collect a large enough database on spin-coating in microgravity and examine the effects of different operation parameters such the spin speed, the dispense rate of the photoresist polymer, and to obtain high-quality video footage of the spin-coating process in microgravity. In addition, the objective is to compare the characteristics of the photoresist film developed in microgravity, and examine the reproducibility of the results by performing repetitive experiments at the same condition in microgravity.

El-Genk said the team hopes to conduct several outreach activities to increase awareness regarding the experiment. Presentations will be conducted at Eldorado and Sandia High Schools as well as at other public schools. A video will also be created to highlight the experiment.

Tom Gamble, is the student team leader, and El-Genk, faculty advisor. The faculty co-advisor is Robert Busch, chemical and nuclear engineering professor. The external technical advisor is Dr. Steve Thornberg from Sandia National Laboratories.

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