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Teos2 allows LPCVD deposition of silicon dioxide, using tetraethyl orthosilicate (TEOS) which can provide a more conformal coating at lower temperature than tylanbpsg films. This is a six inch tube.

Teos2 Furnace Operation (short)


Clean substrates

Diffusion clean with HF last


Enable the furnace on Coral


Verify Pump program running

Go to the furnace and use the STATUS button to verify that the system is in 'RUN' mode and running the “PUMP program”. 

End Pump program 



Verify the Tube is vented

Twenty minutes after the pump program has ended you must manually test that the tube is vented. Push MANUAL on the boat puller, push FAST, then LOOK AT THE TUBE while you hold down OUT. You should immediately see the boat start to come out.  If it does not, stop and wait 10 more minutes and test it again.


Load your program (only after verifying manually that tube is vented)

From TYCOM type "LO  <program name>  <furnace#>" <RET>.  You will be asked to enter the deposit time.


Run program


Load your wafers


Send in tube



Monitor furnace

Take pressure readings during the gross leak check, leak check and the deposition steps of the program and write the values in the logbook.


Unload wafers


End program



Load pump program


Run Pump program


Measure wafers and log results


Disable the furnace on Coral.


Process Monitoring and Machine Qualification

Qualification Results:


To provide a standard procedure to monitor Poly thickness and uniformity both wafer-to-wafer and within-a-wafer.

Deposition material: Silicon dioxide

Expected deposition thickness: 1000 A



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.



Test results are recorded on Coral.



  1.  Use two new 'L' test wafers; <100>, P-type (boron), 10-20 ohm-cm.
  2.  Clean at wbdiff in the following sequence;  5:1:1 H2O:H2O2:NH4OH ten minutes, rinse, 5:1:1 DI;HCl:H2O2 ten minutes, rinse, 50:1 DI:HF 30 sec, rinse, spin dry.
  3.  Load program TEOS2STD into Teos2 furnace.  This will deposit a layer of silicon dioxide onto the wafers. Time variable is 00:16:00.
  4.   Load wafers into boats using clean (non-teflon) tweezers or vacuum wand.  Load wafers with the major flat up into the boats in the following positions:

1st boat: (Front, 1st boat to come out of furnace), 20 empty slots,

1st  two dummies, (slots 21 & 22)

1st boat:  two test wafers (slot 23 & 24),

1st boat: one dummy (slot 25, slot farthest towards back of furnace)




1. Measure the thickness and index of refraction at 9 points across the wafer using woollam using Silicon Oxide (100 - 10,000 Ang)

2.  Report the average thickness, standard deviation, and n at 633 nm for the wafer



Record results on the on Badger. If test’s values are not within 10% of plotted test average, 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.




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