Solvent Wet Benches
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A batch of wafers in a suitable process cassette are spun at high speeds while being sprayed with solvent, rinsed with DI water, then
spun dry. Some spin tools accommodate a single cassette of wafers while others accommodate several cassettes per run. These tools
do a good job and are in just about every FAB.
However, spin tools do have some drawbacks compared to submersion wet benches:
·Spin tools require a balanced load. If some wafers are missing from the lot, the entire lot can be destroyed, and sometimes the tool
itself is damaged.
·Missing wafers are common enough. It's a nuisance for operators to manage a situation of adding dummy wafers, usually manually by
vacuum wand. Then, removing those dummy wafers afterwards.
·Spinning is said to be hard on wafers and is thought to contribute to chips, micro cracks, and occasional wafer breakage.
·Drying by mechanical spin is not as efficient as with IPA Vapor or Marangoni style drying.
Automated Solvent Wet Bench
Manual Solvent Wet Bench
Because of the dangerous flash points associated with solvents, it is necessary to take certain safety precautions.
Shown here is a parts cleaning wet bench constructed of stainless steel. It clearly shows the on board fire suppression typical of all solvent benches installed in FABs today.
Manual Solvent Wet Bench designed for parts cleaning
Solvent Wet Benches are common in BEOL (Back End of Line) wet processing because at that stage of manufacturing, wafers have metal on them. Common acid chemistries used in FEOL processes can damage the BEOL structure, so solvents are popular BEOL cleaning chemicals.
1.Resist and residue removal (post ash clean)
2.Post Etch polymer Cleans
3.Post CMP Cleaning
4.Lift Off (usually in less sophisticated FABs)
Solvent Wet Benches:
Just a few submersion style solvent wet benches are found in most FABs compared to the many acid wet benches used in FEOL.For years,
the world’s leading wet bench suppliers refused to manufacture solvent benches.Perhaps this is why spin spray tools grabbed lots of
BEOL market share.Or, maybe spin cleaners are the better tool for the Job?Either way, it’s worth mentioning Spin Tools in this wet
bench focused website because almost every FAB has them.
Wet Benches For Sale
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Solvent Wet Benches:
Common BEOL Wet Bench Chemistries:
Solvents of many brands and varieties are common BEOL chemicals. Some common solvents are IPA, EKC, KOH, NMB, NMP, PGMEA, and many more.
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