Equipment
Lab and Coral NameTRL / rca-TRL
Model0
SpecialistEric Lim    (Robert Bicchieri)
Physical Location4F Main-South
Classification
Process CategoryDiffusion
SubcategoryClean
Material KeywordsAcids
Sample Size6" Wafers, 4" Wafers
AlternativeICL / rca-ICL
Keywordsmulti wafer, manual load, both sides of sample, isotropic etch, temperature, manual operation
Description
The rca-TRL is a wet station dedicated for pre-diffusion wafer cleans using the RCA cleaning procedure. It consists of 3 chemical baths: SC1 for organic cleaning, SC2 for ionic cleaning and a diluted HF bath to remove a thin oxide layer from the wafer surface. Each bath has its own dedicated quick dump rinser. This wet bench does not allow metals or wafers that have seen metals. On an exception basis (PTC approved), a modified RCA clean may be run using this wet station. Unlike the rca-ICL, this tool in TRL allows cleaning of GREEN wafers that have been in the sts2 (to clean DRIE wafers prior to thermal oxidation, in a process sequence to remove DRIE etch residues from trench sidewalls)

Best forPre-diffusion cleaning. GREEN sts2 wafers are permitted.
LimitationsNo metals.
Characteristics/FOMSC1 at 80C, SC2 at 80C, 50:1 DI:HF standing bath
Caution withWet chemical processing
Machine Charges (academic rate)25pu/tank
Documents

SOP
RCA for TRLSOP for the RCA cleans in TRL
Process Matrix Details

Permitted
Germanium on surfaceSamples with germanium on the surface (typically grown films)
,
Germanium buriedSamples with germanium buried below a different film
,
PiecesWafer pieces may not be handled by the equipment, and are harder to thoroughly clean - preventing them from running in certain tools.
,
Been in the STS DRIEThe DRIE etch leaves behind polymer residues on the sidewall ripples, which can be a contamination concern for some tools.
,
Been in the SEMA sample viewed in the SEM must have used the appropriate chuck to avoid cross-contamination
(With Appropriate Chuck),
Been in the Concept1The Concep1 deposits dielectrics on GREEN wafers, however it also accepts metal and there can be cross-contamination for diffusion area
,
Coming from KOHAfter a KOH etch, the samples must receive a special clean because the K ions are highly contaminating to CMOS frontend tools
,
Coming from CMPAfter a CMP, the samples must receive a special clean, because the slurry residues otherwise introduce contamination and particles.


Not Allowed
Ever been in EMLSamples from EML are never permitted to return to ICL or TRL
,
Been in the ALDSamples that have been in any of the ALD systems
,
Pyrex SubstratesPyrex substrates can be a concern due to high sodium content, which contaminates CMOS frontend tools
,
III-V SubstratesAny III-V substrates, e.g. GaAs, GaN, InP, and so on. Note though that many common III-V substrates will also carry the Au flag, but there are some GREEN III-V substrates.
,
Gold or RED color codeRED color code substrates. These are gold-contaminated or have been processed in gold contaminated tools. Gold and other metals can contaminate silicon devices (GREEN color code) and have to be separated.
,
Any exposure to CMOS metalIf the sample had ever seen a CMOS metal (or a tool that accepts CMOS metal), then some frontend tools could be contaminated by this.
,
CMOS metal on surfaceCMOS compatible metals exposed on the surface. These are Al,Ni,Pt,Ti,TiN. Other metals such as Au are *NOT* part of this.
,
CMOS metal buriedCMOS compatible metals covered entirely by a different material. These are Al,Ni,Pt,Ti,TiN. Other metals such as Au are *NOT* part of this.
,
Has PhotoresistSamples with photoresist cannot be exposed to high temperatures, which is typical in deposition tools. Outgassing can be a concern.
,
Has PolyimidePolyimide is a very chemically resistant polymer, and can tolerate higher temperatures but cannot be exposed to typical PECVD deposition temperatures or diffusion furnaces. Outgassing can be a concern.
,
Has Cured SU8Not fully cured SU8 residues can heavily contaminated plasma chambers or destroy other user's samples, but fully cured SU8 is permitted in certain tools.


For more details or help, please consult PTC matrix, email ptc@mtl.mit.edu, or ask the research specialist (Eric Lim)