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best_practices_for_handling_chips [2018/06/21 11:16]
ethanminot
best_practices_for_handling_chips [2018/06/21 11:19] (current)
ethanminot
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 {{:​hold_chip_on_edge.jpg?​200|}} When you pick up a chip, don't let the tweezers go more than 2 mm past the edge {{:​hold_chip_on_edge.jpg?​200|}} When you pick up a chip, don't let the tweezers go more than 2 mm past the edge
  
-|{{::​washing_chips.jpg?​400|}}|When you wash a chip, the spray from the bottle should be hit the chip and flow towards your tweezers. Don't put the tweezers upstream of the chip. This is easier said than done because liquid will tend to flow down the tweezers onto your gloves. Experiment with a dummy chip. Transition between acetone and IPA quickly, never let the acetone evaporate before you have a chance to rinse it off with IPA. Similarly, transition between IPA and DI water quickly.|+|{{::​washing_chips.jpg?​350|}}|When you wash a chip, the spray from the bottle should be hit the chip and flow towards your tweezers. Don't put the tweezers upstream of the chip. This is easier said than done because liquid will tend to flow down the tweezers onto your gloves. Experiment with a dummy chip. Transition between acetone and IPA quickly, never let the acetone evaporate before you have a chance to rinse it off with IPA. Similarly, transition between IPA and DI water quickly.|
  
 |{{::​blowing_dry.jpg?​400|}}|Blow drying a chip can be tricky. Too much power and the chip flies out of your tweezers. Too little drying time and liquid remains under the tweezers. I like to support the chip on a cleanroom wipe while I blow off most of the liquid (be careful, the cleanroom wipe will flap around if you are not careful). Then I put down the chip and blow off the tweezers. Then I pick up the chip in a different spot and get any remaining liquid.| |{{::​blowing_dry.jpg?​400|}}|Blow drying a chip can be tricky. Too much power and the chip flies out of your tweezers. Too little drying time and liquid remains under the tweezers. I like to support the chip on a cleanroom wipe while I blow off most of the liquid (be careful, the cleanroom wipe will flap around if you are not careful). Then I put down the chip and blow off the tweezers. Then I pick up the chip in a different spot and get any remaining liquid.|
  
 ===== Dicing wafers into pieces ===== ===== Dicing wafers into pieces =====
 +
 +**Danger:** Wear safety glasses when breaking silicon into pieces.
  
 Sometimes you have to break (cleave) a whole wafer into smaller pieces. The small pieces are called dies or chips. It's helpful to have two pairs of wafer-handling tweezers for this process: Sometimes you have to break (cleave) a whole wafer into smaller pieces. The small pieces are called dies or chips. It's helpful to have two pairs of wafer-handling tweezers for this process:
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 {{::​wafer_tweezer.jpg?​400|}} {{::​wafer_tweezer.jpg?​400|}}
  
-This process works best with a silicon (1,0,0) wafer. The wafer has a flat edge to show you which way it will naturally break (along the crystal axis). Use a diamond scribe to scratch a notch on the flat edge. The depth of the notch should be about 10% of the wafer thickness. ​Then grab the wafer on either side of the notch and twist.+The process works best with a silicon (1,0,0) wafer. The wafer has a flat edge to show you which way it will naturally break (along the crystal axis). Use a diamond scribe to scratch a notch on the flat edge. The depth of the notch should be about 10% of the wafer thickness. ​Use wafer-handling tweezers to grab the wafer on either side of the notch, then gently ​twist.
  
-{{::​break_wafer.jpg?​500|}}+{{::​break_wafer.jpg?​460|}}
  
 After the wafer is broken down into smaller pieces you can use a different technique. Notch the silicon piece where you want the crack to start. Place the silicon piece on a glass slide (or two glass slides) so the notch lines up with the edge of the glass. Use the back end of tweezers to apply gentle pressure to either end of the silicon piece. ​ After the wafer is broken down into smaller pieces you can use a different technique. Notch the silicon piece where you want the crack to start. Place the silicon piece on a glass slide (or two glass slides) so the notch lines up with the edge of the glass. Use the back end of tweezers to apply gentle pressure to either end of the silicon piece. ​
  
-{{::​break_piece.jpg?​500|}}+{{::​break_piece.jpg?​480|}}

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