Specific Process Knowledge/Thin film deposition/Deposition of Silicon

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PolySilicon can be deposited in several Nanolab 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

DTU Nanolab 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 systems 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
Si sputter deposition in the Wordentec
Si sputter deposition in the Sputter-System (Lesker) - includes information on surface roughness and stress

Deposition of Silicon using PECVD

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

Si deposition using PECVD3

Comparison of the methods for deposition of Silicon

	4" and 6" Furnace PolySi (Furnace LPCVD PolySi)	PECVD (PECVD)	Sputter (Wordentec)	Sputter (IBE/IBSD Ionfab 300)	Sputter (Lesker)	Sputter (Sputter-system Metal-Oxide (PC1) and Sputter-system Metal-Nitride (PC3))
General description	LPCVD (low pressure chemical vapour deposition) of a-Si and poly-Si	Plasma Enhanced Chemical Vapor Deposition of Si	Sputter deposition of Si.	Ion beam sputter deposition of Si.	Sputter deposition of Si.	Sputter deposition of Si.
Doping facility	Yes, B (boron) and P (phosphorus)	Yes, B and P	None	None	None	None
Pre-clean	New wafers can go directly into the furnace. Processed wafers have to be RCA cleaned		RF Ar clean available	None	RF Ar clean available	RF Ar clean available
Layer thickness	~5 nm to 2 µm, if thicker layers are needed please ask the furnace team.	few nm to ~ 300 nm	few nm to ~ 300 nm	No defined limits	few nm to >200 nm	few nm to ?
Deposition rate	undoped, boron doped:~100 Å/min Phosphorous doped:~20 Å/min	~6 Å/s can probably be higher	On the order of 1 Å/s dependent on process parameters. See more here.	About 5 nm/min. See more here.	Depends on process parameters, roughly 0.2-2 Å/s. See Process Log.	Depends on process parameters, at least 0.3 Å/s, see conditions here
Process temperature	560 °C (amorphous) and 620 °C (poly)	300 °C	close to room temperature	Platen: 5-60 °C	Wafers can be heated to 400 °C	Wafers can be heated to 600 °C
Step coverage	Good	Medium	Medium	Not known	Medium	Medium - may be possible to improve using HIPIMS
Adhesion	Good for fused silica, silicon oxide, silicon nitride, silicon	Not tested, but do not deposit on top of silicon		Not tested
Batch size	1-30 wafers (4" furnace) 1-25 wafes (6" furnace)	Several small samples 1-2x 50 mm wafer 1x 100 mm wafer 1x 150 mm wafer	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	Up to 10x6" or 4" wafers many smaller pieces
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)	See the cross contamination sheets	Silicon wafers Quartz wafers Pyrex wafers	Same materials as on the allowed materials below	Almost any that does not degas, see cross-contamination sheet	Almost any that does not degas, see cross-contamination sheets
Allowed material	*Only those above (under allowed substrates).	See the cross contamination sheets	Silicon oxide Silicon (oxy)nitride Photoresist PMMA Mylar SU-8 Metals	Silicon, silicon oxides, silicon nitrides Metals from the +list and the -list on the cross-contamination sheet Alloys from the above list Stainless steel Glass III-V materials Resists Polymers Capton tape	Almost any that does not degas, see the cross-contamination sheet	Almost any that does not degas, see the cross-contamination sheets
Comment		Only in PECVD3		The system is used both for IBSD and IBE. Si deposition can only be performed when it is set up for IBSD.