Volume Epitaxial Growth of Enhanced Mode HIGFETs using Minimal Material Characterization and Rapid Inline Processing to Minimize Risk
Michael Pelczynski, Mark Rittgers, Bob Duffin, Celicia Della-Morrow, Mikhail Mikhov*
Motorola Inc. Semiconductor Product Sector, Test and Manufacturing, CS-1
Tel: (480) 413-3121 Email: email@example.com
of Electrical Engineering,
Keywords: HIGFET, EMODE, epitaxial growth, MOCVD, OMVPE.
Previously, our epi-manufacturing group has reported on the growth of enhancement mode HIGFETs for cell phone applications . Since that report two Emcore E-450 Turbo-Disk reactors have been installed capable of 5x6-inch growth. Both reactors are qualified to run the HIGFET product with a combined maximum average output of between 900-1000 wafers/week. The original single wafer epitaxial growth tool output was about 150 HIGFET wafers/week. There is a significant possibility of increased scrap events from improper epi due to the increased output of the two reactors, the difficulty in projecting the device electrical parameters from the finished epi, and the length of time between insertion in the line and initial test results. Our enhancedmode HIGFET structure (EMODE) is a fully depleted structure [2, 3] and does not lend itself to many standard production-oriented characterization techniques. Typically, one would use Hall, photoluminescence (PL) , and/or x-ray measurements to analyze this type of structure (with higher grown-in charge). These methods have limited correlation in this case . Therefore, to minimize risk, we have developed a basic set of non-destructive characterization tools and coupled it with rapid processing to get initial electrical data. We use a Lehighton measurement coupled with a PL measurement as a pass/fail test after growth. The range and value of the Lehighton measurement can give us information about the charge level in the epi structure in general. We can then use the full-width-at-half-max value of the PL spectra to get information about the amount of the charge in the channel region. In this way we can tell the amount and general location of charge in the structure. Neither test is sufficiently accurate to measure electrical performance absolutely, but is instead useful as a go-no-go to the next step. Once the wafers pass the initial testing they are put into the process line. Rapid in-line results are obtained in four days, which give initial electrical parameter results. Based on these electrical results the wafers are qualified or downgraded.