Equipment
Lab and Coral NameTRL / B4-Poly
ModelMRL 718
SpecialistEric Lim    (Robert Bicchieri)
Physical Location4F Entry Diffusion
Classification
Process CategoryDiffusion
SubcategoryCVD
Material KeywordsSilicon
Sample Size6" Wafers, 4" Wafers
AlternativeICL / 6B-Poly
Keywordsmulti wafer, manual load, multiple pieces, both sides of sample, conformal dep, temperature, manual operation
Description
Tube B4-Poly is a LPCVD system designed to deposit amorphous/polycrystalline Si (depending on the deposition temperature) using SiH4 in the temperature range of 560-630C on Si wafers without any prior metals or III-V processing. Individual process recipes must be written for a given pair of deposition temperature and time values. Process recipes are designed to run in the "reaction rate limited regime” to guarantee deposition uniformity across the wafers. Wafers are loaded manually with a boat loader and two rods.

Best forPoly deposition on metal free Si wafers
LimitationsNo metals or III-Vs
Characteristics/FOMGases: SiH4, N2, Deposition rate 100 A/min, deposition pressure 250 mTorr
Caution with
Machine Charges (academic rate)65pu/run + 70pu/um
Documents

SOP
Tube B4SOP for the tube B4
Process Matrix Details

Permitted
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)
(A),
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.
,
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.
,
Requires TRL RCA CleanAn RCA clean in TRL was carried out immediately before
(Must do)

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
,
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.
,
Has been past RCA clean for over 4 hoursFor some diffusion furnaces, the samples must immideatly enter the furnace and cannot be stored in a box for a long time.


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