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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 the deposition of PolySilicon using Low Chemical Vapour Deposition (LPCVD).

We have a 6" furnace (installed in 2011) for the 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 the 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 PECVD

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

Deposition of Silicon using sputter deposition

At Nanolab we can sputter silicon with the Lesker Sputter systems (both the single chamber and dual chamber systems). One of the advantages of sputtering is that you can deposit on almost any material you like. In the cluster system you can heat the substrate up to 600 °C.

It was previosly possible to sputter Si with our IonFab 300. You can read about the deposition conditions and results from that here.

Some parameters for sputter deposition of Si in the now-decomissioned Wordentec are found here.

Deposition of Silicon using e-beam evaporation

It is possible to e-beam evaporate silicon at Nanolab using the E-beam evaporator (10-pockets), where the substrate can be heated up to 250 °C. As with sputtering you can deposit on almost any material. In e-beam evaporation the deposition is line-of-sight and will be suitable for lift-off. However for 8" wafers the system is not optimized for lift-off on the full diameter of the wafer.

Comparison of the methods for deposition of Silicon

4" and 6" Furnace PolySi (Furnace LPCVD PolySi) PECVD (PECVD) Sputter (Lesker) Sputter (Sputter-system Metal-Oxide (PC1) and Sputter-system Metal-Nitride (PC3)) E-beam evaporation (E-beam evaporator (10-pockets))
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. Sputter deposition of Si. E-beam evaporation of Si.
Doping facility Yes, B (boron) and P (phosphorus) Yes, B and P None None None
Pre-clean New wafers can go directly into the furnace. Processed wafers have to be RCA cleaned   None RF Ar clean available None
Layer thickness ~5 nm to 2 µm, if thicker layers are needed please ask the furnace team. few nm to ~ 600 nm few nm to >200 nm few nm to ? few nm to 600 nm
Deposition rate
  • undoped, boron doped:~100 Å/min
  • Phosphorous doped:~20 Å/min
 ~6 Å/s can probably be higher 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 1 Å/s
Process temperature 560 °C (amorphous) and 620 °C (poly) 300 °C room temperature room temperature to 600 °C room temperature to 250 °C
Step coverage Good Medium Medium Medium - may be possible to improve using HIPIMS no step coverage unless using tilt holder, in which case the step coverage can be very good and can be tuned.
Adhesion Good for fused silica, silicon oxide, silicon nitride, silicon Not tested, but do not deposit on top of silicon      
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
  • Up to 1x6" wafers
  • smaller pieces
  • Up to 10x6" or 4" wafers
  • many smaller pieces
  • Up to 4 x 6" wafer or
  • 3x 8" wafers (ask for special holder)
  • 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.
  • Almost any that does not degas, see cross-contamination sheet
  • Almost any that does not degas at your intended substrate temperature. See also cross-contamination sheets.
  • Almost any that does not degas at your intended substrate temperature. See also cross-contamination sheet.
Allowed material *Only those above (under allowed substrates).
  • See the cross contamination sheets
  • Almost any that does not degas, see the cross-contamination sheet
  • Almost any that does not degas, see the cross-contamination sheets
  • Almost any that does not degas, see cross-contamination sheet
Comment Only in PECVD3
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