Equipment
Lab and Coral NameTRL / Greenflo
Model0
SpecialistDavid Terry    (Paul Tierney)
Physical Location4F Hallway
Classification
Process CategoryWet
SubcategoryAcids
Material KeywordsSilicon, III-V, GaN, Quartz, Pyrex, SiO2, SiNx, Dielectrics, CMOS Metals, Non-CMOS Metals, Non-Standard Materials, 2D Materials, Photoresist, Acids
Sample Size6" Wafers, 4" Wafers, 7" Photo Plates, 5" Photo Plates, Pieces
AlternativeTRL / acid-hood
Keywordsmulti wafer, manual load, multiple pieces, both sides of sample, isotropic etch, temperature, manual operation
Description
The Greenflo is a wet station that is used for RED and GREEN processesfor cleaning and etching purposes with acidic/basic solutions. It is primarily designed for full wafer (6", 4'..) or pieces. Appropriate beakers are required as some chemicals which may not be suitable with glass such as HF. Gown up with apron, face shield, arm protectors and rubber gloves. Thin vinyl gloves and clean room suits do not provide enough protection against corrosive and hazardous chemicals. Get chemicals from the chemical "pass-through" and use the cart to transport them to the acid-hood. Use the small amounts of chemicals left in the bottles by previous users before proceeding to open a new bottle. After done with the process aspirate acids from the beaker in the acid hood. Before de-gowning, clean beakers/cassetts with DI water and place them at right place. No solvent is allowed in Greenflo.

Best forChemical cleaning and etching
LimitationsRCA cleans are difficult to perform because this station does not have hotplates built-in.
Characteristics/FOMacid wet bench
Caution withGown up with apron, face shield, arm protectors and rubber gloves. Do not touch anything in the acid hood area with only vinyl gloves. Be sure about chemical characteristics before planning to use it. Very important to be attentive all the times.
Machine Charges (academic rate)25pu/tank
Documents

SOP
Greenflow Acid hoodSOP for the Greenflow acid hood
Wet ProcessingRules and guidelines for wet processing
Acid hoodHow to operate the acid hood and safety rules
Chrome masksHow to make chrome masks from transparancies
Acid hood rulesRules and guidelines for the acid hood

Documents
Etch rates part 2Berkeley etch rate paper
Etching of III-V'sAn exhautive/ing collection of etch recipes for III-V materials
Process Matrix Details

Permitted
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.
,
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.
,
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.
,
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
,
Been in the Concept1The Concep1 deposits dielectrics on GREEN wafers, however it also accepts metal and there can be cross-contamination for diffusion area
,
Has PhotoresistSamples with photoresist cannot be exposed to high temperatures, which is typical in deposition tools. Outgassing can be a concern.
(Removes),
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.
(Removes),
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.
,
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


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