Tweezers are generally divided into two main groups; those to be used for standard nonmetal processing (Si, SiGe, Quartz or Sapphire) and those used for standard metal processing (Al, Ti or W).
Tweezers are available in the stockroom.
Most furnaces and LPCVD's have designated quartz vacuum wands for loading and unloading wafers at the station. Use of the tweezers at those stations is optional, but the appropriate tweezers must be used. An example of tweezer use as opposed to wand use for loading would be if the wand is broken, or wafers are polished on both sides.
The tweezers must be cleaned before using them. In most cases the storage box must be cleaned too. A description of the correct cleaning procedures follows below.
There are designated beakers for the cleaning of tweezers. Nancy Latta can show you where it is. All tweezer cleaning is done at wbnitride or litho solvent wetbench.
Carefully examine the tweezers before cleaning for slices, peeling or cracks in the teflon coating. Replace them if you find flaws.
Never use metal tweezers which do not have a teflon coatings. They are a source of contamination in the Lab.
Teflon coated tweezers and all tools which come in contact with wafers must be thoroughly degreased in solvents before use in the Lab.
Degrease by soaking in Acetone, Methanol, and Isopropyl Alcohol for 10 mins each. Use quqrtz beaker available from Mahnaz Mansourpour . Do the cleaning at the litho solvent bench.
Blow dry using N2 gun at the solvent bench.
Place tweezers in a clean storage box with the tips oriented toward the end
of the box marked TIPS. This will insure that contaminates from gloved hands
and fingers will not transfer to the ends of the tweezers which will be in contact
with the wafers.
Boxes are cleaned out using Isopropyl Alcohol (squeeze bottle is ok) and given an air or blow dry. The box is then LABELED in the following way;
TIP is written on top of the box on one end. This marks where the working end of the tweezers will be orientated each time they are placed into the box. This prevents contaminates from handling from getting on the tips.
Your NAME must be written on the top of the box.
The TYPE of tweezers is marked on the top of the box, i.e. clean metal, dirty
If you are processing with nonstandard materials (that is, working mostly
at the general wetbench) you MUST have designated tweezers for that work. You
will need a dirty pair and a clean pair if you plan to clean substrates for
deposition systems or other clean processes. You should clean these tweezers
in your own glassware using the methods described above.
CAREFULLY LABEL THE BOX and write on the handle end in black marker the name
of the material they will be used for (gold, KOH, Pt, Cr, Pd, PtSi, Cu, Co,
ITO, GaAs, Ni, FeCl, etc...) So that you or someone else in the Lab does not
use them and unknowingly contaminate wafers and/or equipment. THIS IS VERY IMPORTANT!
Failure to do this could ruin months of work by your fellow facility users and
Do not use other people's tweezers without their express permission.
Stanford Nanofabrication Facility
Last Modified 08/29/2003