Specific Process Knowledge/Thin film deposition/Furnace LPCVD Nitride

LPCVD (Low Pressure Chemical Vapor Deposition) Silicon Nitride

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.

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 SRN: Silicon Rich Nitride
Performance	Film thickness	Si₃N₄:~50Å - ~3000Å SRN: ~50Å - ~10000Å
	Step coverage	Good
	Film quality	Dense film Few defects
Process parameter range	Process Temperature	800-835 ^oC
	Process pressure	80-230 mTorr
	Gas flows	SiH $_{2}$ Cl $_{2}$ :10-100 sccm NH $_{3}$ :10-75 sccm
Substrates	Batch size	1-25 4" wafer per run Deposition on both sides of the substrate
Substrates	Substrate material allowed	Silicon wafers (new from the box or RCA cleaned) with layers of silicon oxide or silicon (oxy)nitride (RCA cleaned) Quartz wafers (RCA cleaned)