Instructions for Tylan Oxidation Process Qualification

 

Purpose: to provide verification and trend of a wet oxidation program and wafer-to-wafer and within-a-wafer uniformity of etch over a 50 wafer load.

 

Frequency of the test: to be completed after major maintenance such as a pull and clean or injector change, or once monthly, or as needed based on user feedback.  Labmembers are encouraged to use this procedure before committing their work to critical runs to check that the furnace is operating correctly.

 

Documentation of results: to be posted on the log sheet located in the assigned book at the tool, posted in the equipment archive for each of the four tylan oxidation furnaces on the SNF website and in a file or webpage available to users in data or chart format.

 

Procedure:

 

  1. From the stock room get four wafers for each furnace, tylan1, tylan2 and tylan3.  Get two wafers for tylan4.  Use ‘L’ stock test wafers.
  2. Clean all wafers using standard pre-diffusion clean, 5:1:1 DI:H2O2:HCl last.
  3. Load wet program WET900 into all furnaces.  Time variable is 00:39:00.  This should grow between 900A and 1100A oxide.
  4. Load the wafers into the furnaces flats up (top) and polished sides facing out (load direction).  Arrange the wafers so that they are in the front and back positions of two boats.  See Fig. 1. Tylan4 will have one wafer in the front position of the first boat and one wafer in the back position of the second boat.  This will represent a 50 wafer spread.  See Fig. 2.
  5. Start the program and monitor the gas flows and temperature of the Load, Center and Source TC’s.
  6. After the program has finished (about 2hr) unload the wafers into the appropriately marked box for the furnace tested.
  7. Measure the wafers using either Nanospec or Nanospec, program 1. Be sure to reference the instrument using the standard wafer.  Take readings for the Center, Flat, Bottom, Right and Left positions of the wafer.  Readings should be taken about 15mm from the edge.  See Fig. 3.
  8. Note the reading for thickness and in the Oxide Thickness Logbook

 

Figure 1:  Wafer placement in tylan1-3 boats

Figure 2:  Wafer placement in tylan4 boats

Figure 3:  Reading placement.  Note that the flat is “up”.