Specific Process Knowledge/Thin film deposition/Deposition of Silicon

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PolySilicon can be deposited in several Danchip tools. Either it can be sputtered or be deposited in the PolySilicon furnace. In the chart below you can compare the two different deposition methods:

Deposition of PolySilicon using LPCVD

Danchip has two furnaces for deposition of LPCVD (Low Chemical Vapour Deposition) polysilicon: A 6" furnace (installed in 2011) for deposition of standard polySi, amorphous polySi and boron doped polySi on 100 mm or 150 mm wafers and a 4" furnace (installed in 1995) for deposition of standard polySi, amorphous polySi, boron- and phosphorous doped polySi on 100 mm wafers. In LabManager the two furnaces are named "Furnace: LPCVD Poly-Si (4") (B4)" and "Furnace: LPCVD Poly-Si (6") (E2)", respectively.

Deposition of Silicon using sputter deposition technique

At DANCHIP you can also deposit silicon using Wordentec, PVD co-sputter/evaporation or IBE Ionfab300 sputter systems. (There is also a Si sputter target in Alcatel, but the process is not running stable nowadays). One of the advantages here is that you can deposit on any material you like.

Comparison of the methods for deposition of Silicon

	4" and 6" Furnace PolySi (Furnace LPCVD PolySi)	Sputter (Wordentec)	Sputter (IBE/IBSD Ionfab 300)	Sputter (Alcatel)	Sputter (Lesker)	E-beam evaporation (III-V Dielectric evaporator)
General description	LPCVD (low pressure cheimical vapour deposition) of polysilicon	Sputter deposition of Si.	Ion beam sputter deposition of Si.	Sputter deposition of Si. Not recommended as first choice for Si deposition.	Sputter deposition of Si.	E-beam evaporation of Si.
Doping facility	Can be doped with boron or phosphorus during deposition	None	None	None	None	None
Pre-clean	New wafers can go directly into the furnace. Processed wafers have to be RCA cleaned	RF Ar clean	None	RF Ar clean	RF Ar clean
Layer thickness	~50Å to 2µm, if thicker layers are needed please ask the furnace team.	10Å to about 3000Å	No defined limits	10Å to 2000Å		10Å to 2500Å
Deposition rate	undoped, boron doped:~100Å/min Phospher doped:~20Å/min	In the order of 1 Å/s, but dependendt on process parameters. See more here.	About 5 nm/min. See more here.	2Å/s to 8Å/s (see below).	Depends on process parameters, roughly 1 Å/s.	1Å/s to 5Å/s (see below).
Process temperature	560 ^oC (amorph) and 620 ^oC (poly)	?	Platen: 5-60 ^oC	?	Wafers can be heated to 100-200°C	20-250 ^oC
Step coverage	Good	.	Not known	Poor		Poor
Adhesion	Good for fused silica, silicon oxide, silicon nitride, silicon	.	Not tested	Bad for pyrex, for other materials we do not know
Batch size	1-30 wafers (4" furnace) 1-25 wafes (6" furnace)	24x 2" wafers or 6x 4" wafers or 6x 6" wafers	Several small samples mounted with capton tape 1x 50 mm wafer 1x 100 mm wafer 1x 150 mm wafer 1x 200 mm wafer	Up to 1x4" wafers smaller pieces	Up to 1x6" wafers smaller pieces	2" chips
Allowed substrates	Silicon wafers (new or RCA cleaned) with layers of silicon oxide or silicon (oxy)nitride from the A, B and E stack furnaces Quartz/fused silica wafers (RCA cleaned)	Silicon wafers Quartz wafers Pyrex wafers	Same materials as on the allowed materials below	Silicon wafers Quartz wafers Pyrex wafers	Silicon wafers Quartz wafers Pyrex wafers	Silicon wafers Quartz wafers Pyrex wafers
Allowed material	Only those above (under allowed substrates).	Silicon oxide Silicon (oxy)nitride Photoresist PMMA Mylar SU-8 Metals	Silicon, silicon oxides, silicon nitrides Metals from the +list Metals from the -list Alloys from the above list Stainless steel Glass III-V materials Resists Polymers Capton tape	Silicon oxide Silicon (oxy)nitride Photoresist PMMA Mylar SU-8 Metals	Silicon oxide Silicon (oxy)nitride Photoresist Metals	III-V materials Silicon wafers Resists
Comment			The system is used both for IBSD and IBE. Si deposition can only be performed when it is set up for IBSD.	This process is not running really stable nowadays.