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wbdecon and wbclean-3

This bench has two units. The left side, wbdecon, has one HCl bath, dump rinser, and SRD for the decontamination of 3", 4" or 6 " KOH-etched silicon wafers before being allowed back into the clean equipment group. The right side of the bench, wbclean-3, has four bath: the chemical baths are: SC1 (5:1:1 H2O:H2O2:NH4OH for removal of trace organics) and SC2 (5:1:1 H2O:H2O2:HCl for removal of trace metal ions), 50:1 HF, for oxide etching and 6:1 BOE for oxide etching.

Picture and Location

Wbdecon
The tool is located at E78 on the Lab Map.

Process Capabilities

Cleanliness Standard

This wet bench is in the Clean Equipment Group.

Special cases: Contact staff or the Prom committee for exceptions.

Materials control policies are governed by equipment groups; for the description of this policy, click <here>.

 

Performance of the Tool

What the Tool CAN do

This bench has two units.
The left side, wbdecon, has one HCl bath (70C), dump rinser, and SRD for the decontamination of 3", 4" or 6 " KOH-etched silicon wafers before being allowed back into the clean equipment group.

The right side ,wbclean-3, will be used as the back up while the new wet bench diffusion will be installed.
The chemical baths are: SC1 (5:1:1 H2O:H2O2:NH4OH for removal of trace organics) and SC2 (5:1:1 H2O:H2O2:HCl for removal of trace metal ions), 50:1 HF, for oxide etching and 6:1 BOE for oxide etching.

 

Substrates

Substrates must be 3" or 4" rounds, which can be handled by the dedicated cassettes at this station. Only silicon, silicon germanium, and quartz substrates may be process at this station, subject to the constraints in the Materials Allowed section (section 1.3). Odd-sized substrates must be processed at wbflexcorr

 

What the Tool CANNOT do

Substrates containing any metal films are strictly prohibited from being processed here, even if the free metal has been previously removed.

 

How to Become a User

 

  1. Read all material on the SNF website concerning the wet bench, including Background, Process Capabilities, Operating Procedures and Process Monitoring.
  2.  View the Diffusion Wetbench Training movie (13 minutes, 106 Mbytes).
  3. View the Delrin Tweezer Cleaning (9 minutes, 37 Mbytes) and the Metal Tweezer Cleaning (9 minutes, 64 Mbytes) movies as well.
  4. Print the SNF Shadowing Form and the wet bench checklist on clean room paper and contact a qualified user of the wet bench to arrange to ‘shadow’ them while they use the tool. You are responsible to be with that labmember for the full time they are operating the tool, and it would be intelligent to ask questions and try to become as familiar as possible with the wet bench during this ‘shadowing.’  You may have to shadow the qualified user more than one time. The qualified user and you will have to sign the SNF Shadowing Form.
  5. Contact SNF training contact on the Equipment Summary page. There is a written test for the tool.

 

Operating Procedures

Read the Wet Bench Operating Instructions for WAFAB benches. Please note these instructions are generic and cover following wet benches: wbdecon and wbclean3.

System Overview


This is a Wafab brand wet bench. It is equipped with: three quartz-lined, temperature controlled hot pots (for NH4OH, and HCl cleans) which aspirate into the acid waste neutralization system; two Teflon-lined tanks (for HF etching) which drain into HF waste collection system; and two dump rinsers and a spin-rinse dryer which drain into the acid waste neutralization system. Each of these modules has its own microcontroller unit, mounted in the overhead control panel. The wet bench also contains a glove wash, an N2 gun, and a DI water hand sprayer. The wet bench plenum, over which all the modules sit, collects runoff and overflow, and drains into the acid waste neutralization system.

Chemical Hazards

Hydrogen peroxide, hydrofluoric acid, hydrochloric acid, and ammonium hydroxide are used at this wet bench. You must read the Material Safety Data Sheets for these chemicals and understand safe chemical handling procedures before working at this station.

The primary hazard classifications for the chemical mixtures used at this bench are:

For 5:1:1 H2O:H2O2:HCl - Corrosive, oxidizer
For 5:1:1 H2O:H2O2:NH4OH Corrosive, oxidizer

For 50:1 HF and 6:1 BOE - Corrosive, toxic

Chemical Frequency

The 5:1:1 H2O:H2O2:NH4OH hot pot should be changed once every four hours.

The 5:1:1 H2O:H2O2:HCl hot pot should be changed every four hours.
HF 50-1 tank should be changed once every 24 hours.
6:1 BOE tank should be changed once per month or as needed.

How to fill the chemical tanks

  • To fill the NH4OH hot pot:
    • Fill DI water to the bottom of the Teflon dip-stick. Then add hydrogen peroxide to the mark on the dip-stick and then add the NH4OH to the last mark on the dip-stick.
  • To fill the HCL hot pot:
    • Fill DI water to the bottom of the Teflon dip-stick. Then add hydrogen peroxide to the mark on the dip-stick and then add the HCl to the last mark on the dip-stick.
NOTE: the H2O2 in both the NH4OH and HCl hot pots will 'boil' off in time and need to be replenished.  This maintains the correct concentration of the mixture.  Simply add H2O2 back to the correct level on the dip-stick

Cassettes

  • There are dedicated cassettes and handles for all wet benches. This bench has Teflon cassettes and handles with a green-colored button. Use only these designated cassettes and handles!
  • There are separate, dedicated cassettes and handles for 3" and 4" wafers. A special stainless steel adapter is required to run 3" cassettes in the spin/rinse dryer.

 

Tweezers

Tweezers used at this station should be Teflon-coated stainless steel. They should be decontaminated according to the standard lab procedures for tweezers cleaning.

 

For detailed decontamination procedure, go to the "KOH etching of Silicon" page or open following link:

KOH decontamination at wbdecon only

 

Additional Process Info

For the procedures of the specific processes which are normally performed at this station, check the Additional Process Info link:
Additional Process Info. Please note these process info are generic and cover following wet benches: wbdiff, wbnonmetal, wbdecon, and wbmetal.

 

 

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