Internship in 8729 Microsystems Processing

1. Internship in 8729Microsystems Processing A Look from Before, During, and After Craig R. Forest July 26, 2001

2. Past, Present, and Future from today�s perspective Background Previous research experience Challenges Faced in 8729 Gold mask metrology Mask layout guide Positive valve indicator 630 base metrology Extracurricular activities Future endeavors Internship Exit Presentation

3. Georgia Tech B.S. Mechanical Engineering in May 2001 Calculus Teaching Assistant ASME President 2000-2001 Engineering Student of the Year, Woodruff School Chair�s Award NASA Five work terms Applied textbook knowledge to real engineering problems Variety of work Operations New spacecraft design and development Research Past

4. Georgia Tech Controls Created simulation of overhead gantry crane Effects of input shaping on operator behavior studied Publication, Conference Manufacturing Researched tool life and tool wear in hard turning process NASA Materials Developed light weight, high strength single-walled nanotube composite materials Previous Research Experience

5. Gold Mask Metrology Challenges in 8729

6. Motivation for Research Problem Quality of LIGA parts depends on mask Compound adhesion problems, sidewall runout Causes X-ray impingement on PMMA above or below threshold value for dissolution Need to understand 3 scales of nonuniformity Wafer scale Part scale Proximity effect Si usually, sometimes other substrate like carbon or �metallized plastic� Or substantially x ray transparent substrate Dimensions (undercut parts, sidewall runout) Exposure duration 3rd bullet Perhaps gold thickness can vary as a function of radius from the center, or part characteristic dimension at a constant radiusSi usually, sometimes other substrate like carbon or �metallized plastic� Or substantially x ray transparent substrate Dimensions (undercut parts, sidewall runout) Exposure duration 3rd bullet Perhaps gold thickness can vary as a function of radius from the center, or part characteristic dimension at a constant radius

7. Approach What can they do? Characterization of capability� Non contact High resolution Metrology of gold thickness is first step in improving the manufacturing process of the mask What can they do? Characterization of capability� Non contact High resolution Metrology of gold thickness is first step in improving the manufacturing process of the mask

8. Repeatabilty Testing Observed correlation between position measurement/temp Consider fluctuation in z-position accuracy Use only relative measurements Mobile clean room installation should alleviate problem Voyager 6X12

9. Mask selected for study Constant diameter features at various distances from wafer center Sinusoidal thickness pattern observed Voyager 6X12

10. Hypothesis Confirmed! Voyager 6X12

11. Six radiographs of three masks with standard (Skala) Analysis using visualization software Photoshop, Spyglass Transform X-ray Radiography�Methods

12. X-ray Radiography�Results Quantitative analysis method developed Maximum 15?m variation in thickness Developing method to measure uniformity of mask thickness Ultimately this tool can be used to measure the thickness anywhere Lots of variation in thicknessDeveloping method to measure uniformity of mask thickness Ultimately this tool can be used to measure the thickness anywhere Lots of variation in thickness

13. Mask is still warped when mounted in synchotron frame Projection onto wafer will be distorted Use X-ray transparent medium to sandwich gold mask (Graphite) Plate stress-free gold Recommendations, Future Work Gold thickness on mask should be above or below threshold for PMMA dissolution If this criterion is met, slight variations in thickness, sidewalls are irrelevant Want to say that parts manufactured with masks used in radiography study are within design tolerances�they work Gold thickness on mask should be above or below threshold for PMMA dissolution If this criterion is met, slight variations in thickness, sidewalls are irrelevant Want to say that parts manufactured with masks used in radiography study are within design tolerances�they work

14. Veeco NT3300 Optical Interferometer Not operational yet (Fall 2001) Capability to examine mask/part topography Vertical resolution of 0.1 nm Quantify bowing, warpage Surface roughness measurements Part inspection Correlate part quality to gold mask metrology Compare as-built part to CAD model Voyager useful for feature inspection Future Work Useful for part inspection to compare to CAD model Thousands of points at different x,y,z locations Non-contact, non-destructive Radiography�ultimately, be able to measure the thickness anywhereUseful for part inspection to compare to CAD model Thousands of points at different x,y,z locations Non-contact, non-destructive Radiography�ultimately, be able to measure the thickness anywhere

15. Motivation Mask layout rules and recommendations not concrete No existing comprehensive, current guidelines document Useful starting point for novice Mask layout guide created Technical explanations and recommendations General guidelines (e.g. symmetry, clusters, rows) Guidelines for specific geometry profiles (e.g. circles, long profiles) Examples Mask Layout Guide

16. Justification Need microdevice actuated by pressure that will not fail negative; weapon application Positive Valve Indicator

17. Contributions Design tweaks Mask layout Manufacturing liaison Assembler Positive Valve Indicator Tests: strength, vibration, thermal cyclingTests: strength, vibration, thermal cycling

18. Challenge Utilize the Voyager�s capability to inspect part Results Analyzed features on front, back Sets of measurements taken and averaged for reliability Compared as-built part to CAD model Reported findings, conclusions 630 Base Metrology

19. Social director for 180 interns Bi-weekly SCuM for social planning Worked with HR to integrate social, professional experience Talent Show Backstreet Boys dance parody NoCal adventures Lake Tahoe SF Gay Pride Parade Napa Valley Biking Mt. Diablo, Black Diamond Mines, Redwood Preserve A�s and Giants games Extracurricular Activities

20. Starting grad school at MIT in Fall MS/PhD program in ME dept Research area Space, MEMS, Precision Machine Design Co-advisors Alexander Slocum, Mark Schattenburg No plans for Summer �02! Future

21. Thank you�