Specific Process Knowledge/Thin film deposition/Furnace LPCVD Nitride: Difference between revisions

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==LPCVD (Low Pressure Chemical Vapor Deposition) Silicon Nitride==
==LPCVD (Low Pressure Chemical Vapor Deposition) Silicon Nitride==
[[image:Furnace_nitride1.jpg|300x300px|right|thumb|B2 Furnace LPCVD Nitride: positioned in cleanroom 2]]
[[image:Furnace_nitride1.jpg|300x300px|right|thumb|B2 Furnace LPCVD Nitride (old nitride furnace) positioned in cleanroom 2]]
At Danchip there are two LPCVD nitride furnaces for deposition of silicon nitride: A new furnace for deposition of stoichiometric nitride on 4" or 6" wafers and a older furnace for deposition of stoichiometric nitride and low stress nitride on 4" wafers. Both furnaces are Tempress horizontal furnaces.  
At Danchip there are two LPCVD nitride furnaces for deposition of silicon nitride: A new furnace (installed in 2008) for deposition of stoichiometric nitride on 4" or 6" wafers and a older furnace (installed in 1995) for deposition of stoichiometric nitride and low stress nitride on 4" wafers. Please, be aware that it is not allowed to deposit low stress nitride in the new nitride furnace (to avoid problems with particles). In LabManager the two furnaces are named "Furnace: LPCVD nitride (6")" and "Furnace LPCVD nitride", respectively. Both furnaces are Tempress horizontal furnaces.  


The LPCVD silicon nitride deposition is a batch process, meaning that you can run a batch of up to 25-35 wafers at a time. The deposition takes place at temperatures of 780-835 degrees Celsius. The reactive gases are ammonia (NH<sub>3</sub>) and dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>). The LPCVD nitride has a good step coverage, and the film thickness is very uniform over the wafers. On the old nitride furnace we have two standard silicon nitride processes: One for deposition of stoichiometric nitride (Si<sub>3</sub>N<sub>4</sub>) and one for deposition of low stress nitride (SNR). On the new nitride furnace we have two standard recipes for deposition of stoichiometric nitride: One for 4" wafers and one for 6" wafers.
The LPCVD silicon nitride deposition is a batch process, meaning that you can run a batch of up to 25-35 wafers at a time. The deposition takes place at temperatures of 780-835 degrees Celsius. The reactive gases are ammonia (NH<sub>3</sub>) and dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>). The LPCVD nitride has a good step coverage, and the film thickness is very uniform over the wafers. On the old nitride furnace we have two standard silicon nitride processes: One for deposition of stoichiometric nitride (Si<sub>3</sub>N<sub>4</sub>) and one for deposition of low stress nitride (SNR). On the new nitride furnace we have two standard recipes for deposition of stoichiometric nitride: One for 4" wafers and one for 6" wafers.

Revision as of 09:20, 18 December 2008

LPCVD (Low Pressure Chemical Vapor Deposition) Silicon Nitride

B2 Furnace LPCVD Nitride (old nitride furnace) positioned in cleanroom 2

At Danchip there are two LPCVD nitride furnaces for deposition of silicon nitride: A new furnace (installed in 2008) for deposition of stoichiometric nitride on 4" or 6" wafers and a older furnace (installed in 1995) for deposition of stoichiometric nitride and low stress nitride on 4" wafers. Please, be aware that it is not allowed to deposit low stress nitride in the new nitride furnace (to avoid problems with particles). In LabManager the two furnaces are named "Furnace: LPCVD nitride (6")" and "Furnace LPCVD nitride", respectively. Both furnaces are Tempress horizontal furnaces.

The LPCVD silicon nitride deposition is a batch process, meaning that you can run a batch of up to 25-35 wafers at a time. The deposition takes place at temperatures of 780-835 degrees Celsius. The reactive gases are ammonia (NH3) and dichlorsilane (SiH2Cl2). The LPCVD nitride has a good step coverage, and the film thickness is very uniform over the wafers. On the old nitride furnace we have two standard silicon nitride processes: One for deposition of stoichiometric nitride (Si3N4) and one for deposition of low stress nitride (SNR). On the new nitride furnace we have two standard recipes for deposition of stoichiometric nitride: One for 4" wafers and one for 6" wafers.

To get information on how to operate the furnace please read the user manuals which are uploaded to LabManager on the machine page.

Process Knowledge

Please take a look at the process side for deposition of Silicon Nitride using LPCVD: Deposition of Silicon Nitride using LPCVD


Overview of the performance of LPCVD Silicon Nitride and some process related parameters

Purpose Deposition of silicon nitride Stoichiometry:
  • Si3N4
  • SRN

Si3N4: Stoichiometric nitride

SRN: Silicon rich nitride (low stress nitride)

Performance Film thickness
  • Si3N4: ~50Å - ~3000Å
  • SRN: ~50Å - ~10000Å

Thick layers have to be deposited over more runs

Step coverage
  • Good
Film quality
  • Dense film
  • Few defects
Film uniformity

New nitride furnace:

  • Uniformity within wafer: ~ 3-4 %
  • Wafer-to-wafer uniformity: ~ 3-5 %
  • Run-to-run uniformity: ~ 3 %

Old nitride furnace:

Process parameter range Process Temperature
  • 780-835 oC

The process temperature depends on the actual process

Process pressure
  • 80-230 mTorr
Gas flows
  • Dichlorsilane (SiHCl): 10-120 sccm
  • Ammonia (NH): 10-75 sccm

The gas flows depend on the actual process

Substrates Batch size

New nitride furnace:

  • 1-25 4" or 6" wafers per run

Old nitride furnace:

  • 1-25 4" wafer per run
  • Deposition on both sides of the substrate
Substrate material allowed
  • Silicon wafers (new wafer from new box or RCA cleaned wafers)
    • with layers of silicon oxide or silicon (oxy)nitride (RCA cleaned)
    • from furnaces in stack A or B in cleanroom 2
  • Quartz wafers (RCA cleaned)