Uniformity Testing Procedure for Tylannitride
Purpose: To provide a standard procedure to monitor Nitride thickness and uniformity both wafer-to-wafer and within-a-wafer.
Frequency of test: to be completed after major maintenance such as a tube change or on a set schedule to be determined or as needed based on user feedback.
Documentation of results: to be posted in hardcopy in the Uniformity Test Book located in the lab, posted in the email archive for the specific furnace and keep in process/maintenance group internal spreadsheet.
††††††††††† Use four new 'L' test wafers; <100>, P-type (boron), 10-20 ohm-cm.
Clean at wbdiff in the following sequence;† 4:1 H2SO4:H2O2 ten minutes, rinse, 5:1:1 DI;HCl:H2O2 ten minutes, rinse, 50:1 DI:HF 30 sec, rinse, spin dry.
††††††††††† Load program NEWLSN into Tylannitride furnace.† Time variable is 00:30:00.
Load wafers into boats using very clean tweezers or vacuum wand.† Load wafers with the major flat up into the boats in the following positions:
1st boat: (Front), 20 empty slots,
1st †two dummies,
1st boat:† two test wafers(slot 23 & 24),
1st boat: one dummy.
2nd boat: one dummy,
2nd boat: two test wafers (slot 2 &3),
2nd boat one dummy,† 21 empty slots.†
Use Nanospec to measure poly thickness at the flat, center, bottom, left and right on each wafer.† Test sites should be no more than about 15mm from the edge of the wafer.† Use the Elipsometer to measure the Refractive index at the center of the wafer.
Record results on the Uniformity Testing Form and post to appropriate email and spreadsheets. If testís thickness values arenít not within 10% of plotted test average or Refractive Index is not 2.0 +/- .1, contact the Diffusion Process/Maintenance team.
Save wafers in a box with the date, furnace number, program name and growth time.† They may be re-tested sometime in the future.