Specific Process Knowledge/Thin film deposition/Deposition of Silicon

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PolySilicon can be deposited in several Danchip tools. It can be sputtered, e-beam evaporated or be deposited in the PolySilicon furnaces. In the chart below you can compare the 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 Nanolab you can also deposit silicon the using Wordentec, the Lesker Sputter system or the IBE Ionfab300 sputter systems. One of the advantages here is that you can deposit on any material you like.

Si deposition in IBE⁄IBSD Ionfab300

Deposition of Silicon using PECVD

At Nanolab you can also deposit silicon the using PECVD. The deposition temperature is 300 ^oC.

Si deposition using PECVD3

Comparison of the methods for deposition of Silicon

	4" and 6" Furnace PolySi (Furnace LPCVD PolySi)	Sputter (Wordentec)	Sputter (IBE/IBSD Ionfab 300)	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.	E-beam evaporation of Si.
Doping facility	Can be doped with boron or phosphorus during deposition	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
Layer thickness	~50Å to 2µm, if thicker layers are needed please ask the furnace team.	10Å to about 3000Å	No defined limits		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.	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
Adhesion	Good for fused silica, silicon oxide, silicon nitride, silicon	.	Not tested
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 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
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 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.