Silicon Metals Bay

Acid Hood - WPS - G14
Location: 1.736
*****
*****Description: Acid Hood

*****Compatible Materials: Si / SiGe

*****Incompatible Materials: III-V
1. Log on to the tool using the LabAccess terminal.
2. Cover hotplate areas with the provided covers.
3. Fill the cascade rinser with DI water and wait until the resistivity is at least 12 MW-cm. This should only take a few minutes. If it does not reach 12 MW-cm, dump tank and restart.
4. Prepare the Piranha solution. Pour 825ml Hydrogen Peroxide into the rectangular quartz tank and then add 1650ml the Sulfuric Acid. If you are processing small samples that do not require this much chemical, please use the smallest amounts of chemical necessary in the ratio (1 part Hydrogen Peroxide : 2 parts Sulfuric Acid) to complete this etch. Cover the piranha beaker with a Teflon cover and allow the solution to sit for 5 minutes.
5. Place wafers into the Piranha solution for 8 minutes.
6. When Piranha clean is completed, place the wafers in the cascade rinser and perform two 5-cycle rinses.
7. Dump cascade rinse and remove wafers unless performing the optional HF native oxide etch.
8. Optional HF etch:
  • a) Pour 1600ml of DI water into the polypropylene tank in the hood and add 80ml of 49% Hydroflouric acid
  • b) Put the wafers into the HF solution until the wafer back de wets (20 seconds).
  • c) Place the wafers back into the full cascade tank for rinsing.
  • d) Perform one 5-cycle rinses. The resistively should reach 12.5MW-cm. If it does not, you have the option to perform additional 5-cycle rinses.

9.If you are drying your wafers by hand, remove them from the cascade tank and carefully blow them dry with the N2 gun.
10. If you are using a vertical shaft spin rinser dryer (SRD) to dry your wafers, you will need to use two carriers of equal size and weight to balance the load during spinning. Load an equal number of dummy wafers into one of the carriers and place it into the SRD. Remove the processed wafers from the cascade tank and place the second carrier into the SRD directly opposite the dummy wafer carrier. Please do not use SRDs in other bays as this can cause cross contamination.
11. Initiate SRD cycle.
12. Turn on the aspirator and plenum rinse to remove the Piranha. If an HF dip was used, aspirate of the HF. When the acid is completely removed, place the aspirator into DI water and run for 2 minutes.
13. Fill and dump each acid container with DI water three times.
14. Turn off the aspirator and plenum rinse.
15. When the SRD is finished, very carefully lift the SRD lid and remove the wafers.
16. DONT FORGET to turn off the DI water taps, rinse beakers, clean-up the hood deck (including covers and dividers) and any empty chemical bottles. Be sure to rinse your gloves.
17. Log off of the tool using the LabAccess terminal.