Specific Process Knowledge/Thin film deposition/Furnace LPCVD Nitride

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6" LPCVD nitride furnace (E3) located in cleanroom E-6
4" LPCVD nitride furnace (B2) located in cleanroom B-1


Deposition of Silicon Nitride using LPCVD

DTU Nanolab has two LPCVD (Low Pressure Chemical Vapour Deposition) furnaces for deposition of silicon nitride:

  • A 4" furnace (installed in 1995) for deposition og stoichiometric nitride on 4 inch wafers.
  • A 6" furnace (installed in 2008) for deposition of low stress/silicon rich nitride on 4 inch and 6 inch wafers. Deposition of stoichiometric nitride on 4 inch wafers is also allowed in this furnace.

In LabManager the two furnaces are named "Furnace: LPCVD nitride (4") (B2)" and "Furnace: LPCVD nitride (6") (E3)", respectively. Both furnaces are Tempress horizontal furnaces.

Please check the cross contamination information in LabManager before you use any of the two furnaces.

The LPCVD silicon nitride deposition is a batch process, where nitride can be deposited on a batch of up to 15 wafers (in the 4" nitride furnace) or 25 wafers (in the 6" nitride furnace) at a time. The deposition takes place under vacuum (120-200 mTorr, depending on the process) and at high temperature (780-845 C, depending on the process). The reactive gases are ammonia (NH3) and dichlorsilane (SiH2Cl2).

The LPCVD nitride has a very good step coverage, and the film thickness is very uniform over the wafers.

The user manuals, quality control procedures and results, user APVs, technical information and contact information can be found in LabManager:

4" LPCVD nitride furnace (B2),

6" LPCVD nitride furnace (E3)


Process information


Manual for the furnace computer to the A, B, C and E stack furnaces

The A, B, C and E stack furnaces can be controlled either from a touch screen by each furnace or from a furnace computer. The user manual for the furnace computer can be found here:

Manual for furnace computers for the A, B, C and E stack furnaces

Equipment performance and process related parameters

Equipment 6" LPCVD nitride furnace (E3) 4" LPCVD nitride furnace (B2)
Purpose Deposition of
  • Silicon rich (low stress) nitride
  • Stoichiometric nitride
  • Stoichiometric nitride
Performance Step coverage
  • Very good
  • Very good
Film quality
  • Deposition on both sides of the substrate
  • Dense film
  • Few defects
  • Deposition on both sides of the substrate
  • Dense film
  • Very few defects
Process parameter range Temperature
  • 810-845 oC

The temperature vary over the furnace tube

  • 780-790 oC

The temperature vary over the furnace tube

Pressure
  • 150 mTorr
  • 200 mTorr
Gas flows

For Low stress nitride

  • Dichlorsilane (SiH2Cl2): 200 sccm
  • Ammonia (NH3): 50 sccm

For Stoichiometric nitride on 6" wafers

  • Dichlorsilane (SiH2Cl2): 45 sccm
  • Ammonia (NH3): 180 sccm
  • Dichlorsilane (SiH2Cl2): 20 sccm
  • Ammonia (NH3): 80 sccm

The gas flows depend on whether nitride is deposited on 4" or 6" wafers

Substrates Batch size
  • 1-25 100 mm wafers
  • 1-25 150 mm wafers

Including a test wafer

  • 1-15 100 mm wafers

Including a test wafer

Allowed materials
  • 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 (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)


Rules for storage and RCA cleaning of wafers to the B2 and E3 furnaces

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