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Teos2 furnace 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.

Operating Procedure

Basic Operation Instructions

  1. Clean substrates
    Diffusion clean with HF last
  2. Enable the furnace
  3. 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."
  4. End Pump program
    ALARM ACK twice
  5. Verify the Tube is vented
    Ten 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.
  6. 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.
  7. Run program
  8. Load your wafers.
  9. Send in tube
    ALARM ACK once
  10. 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.
  11. Unload wafers
  12. End program
    ALARM ACK twice
  13. Load pump program
  14. Run Pump program
  15. Measure wafers and log results
  16. Disable the furnace


Process Monitoring and Machine Qualification

Each month, tool qualification runs are performed on most tools in the SNF to monitor variations in each tool’s performance. The purpose of the Teos2 qual is to monitor deposition accuracy and uniformity. The qual is performed by SUMO members, but users may perform the specified qual process before tool use if more recent qual data is desired for reference.

For more information on the SNF tool performance monitoring system and SUMO, please see the Monthly Tool Monitoring page under the Equipment tab on the SNF wiki.


Qual Process Overview

The Teos2 qual runs two freshly cleaned 4" Si wafers through the TEOS2STD for 16 minutes to be coated with 1,000A SiO2. After the deposition, the wafers are analyzed via Woollam using the nine point Silicon Oxide (100 - 10,000 Ang) analysis.



Wafers for Processing

SUMO Wafer #
(all Si 4" wafers)
Location to be Tested
21 Front
22 Back



  1.  Use two new 'L' test wafers; <100>, P-type (boron), 10-20 ohm-cm
  2.  Clean wafers 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 (from first boat to come out of furnace):
        • 20 empty slots
        • two dummies (slots 21 & 22)
        • two test wafers (slot 23 & 24)
        • one dummy (slot 25, slot farthest towards back of furnace) 


Post-Deposition Measurements

  1. Measure the thickness and index of refraction at 9 points across the wafer using Woollam program Silicon Oxide (100 - 10,000 Ang).
  2. Report the average thickness, standard deviation, and n at 633 nm for the wafer. Test sites should be no more than about 15mm from the edge of the wafer.


Reported Data

Qual data may also be found on the Badger comment log. The following data is reported for the Teos2 qual.

  • average deposition thickness
  • one standard deviation
  • index of refraction

If test 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.


Qualification Results

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