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

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6" LPCVD nitride furnace (E3) located in cleanroom E-6

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)

Furnace computer manual

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

Process information

Using LPCVD silicon nitride as a masking material for KOH etching

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
Performance	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

Storage and cleaning of wafer to the B2 and E3 furnaces

@@ Line 1: / Line 1: @@
-At the moment we have one LPCVD furnace for nitride depositions.
+'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php/Specific_Process_Knowledge/Thin_film_deposition/Furnace_LPCVD_Nitride click here]'''
-==A few words about the furnace==
+<i> Unless otherwise stated, this page is written by <b>DTU Nanolab internal</b></i>
-The furnace is a Tempress horisontal furnace. The process is a batch process meaning you can run a batch of 25 wafers at a time. The deposition takes place at temperatures of 800-835 degrees Celsius. The gases involved are Ammonia and dichlorsilane. The LPCVD nitride has a good step coverage and the film thickness is very uniform over the wafer. We have two standard LPCVD nitride processes: One for depositing stoichiometric nitride (Si<sub>3</sub>N<sub>4</sub>) and one for deposition of low stress nitride (SNR).
+[[Category: Equipment|Thin film F]]
+[[Category: Thin Film Deposition|LPCVD nitride]]
+[[Category: Furnaces|LPCVD nitride]]
-{| border="1" cellspacing="0" cellpadding="3" align="center"
+[[image:DC_nyhed_3.jpg|320x320px|right|thumb|6" LPCVD nitride furnace (E3) located in cleanroom E-6]]
-!
+[[image:Furnace_nitride1.jpg|300x300px|right|thumb|4" LPCVD nitride furnace (B2) located in cleanroom B-1]]
-! LPCVD
-|-
-| Stoichiometry
+==Deposition of Silicon Nitride using LPCVD==
-|
-*Si<sub>3</sub>N<sub>4</sub>
+DTU Nanolab has two LPCVD (Low Pressure Chemical Vapour Deposition) furnaces <!--[[Specific Process Knowledge/Thin film deposition/B2 Furnace LPCVD Nitride|LPCVD furnaces]]--> for deposition of silicon nitride:
-*SRN
+*A 4" furnace (installed in 1995) for deposition og stoichiometric nitride on 4 inch wafers.
-SRN: Silicon Rich Nitride
+*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 (NH<sub>3</sub>) and dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>).
+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:'''
+[http://labmanager.dtu.dk/function.php?module=Machine&view=view&mach=84 4" LPCVD nitride furnace (B2)]
+[http://labmanager.dtu.dk/function.php?module=Machine&view=view&mach=250 6" LPCVD nitride furnace (E3)]
+[https://labmanager.dtu.dk/d4Show.php?id=1926 Furnace computer manual]
+== 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:
+[[media:Furnace_computer_manual.pdf|Manual for furnace computers for the A, B, C and E stack furnaces]]
+<!--hide text
+[[/Standard recipes, QC limits and results for the 4" nitride furnace|Standard recipes, QC limits and results for the 4" nitride furnace]]
+<br/>
+[[/Standard recipes, QC limits and results for the 6" nitride furnace|Standard recipes, QC limits and results for the 6" nitride furnace]]
+<br/>
+hide text-->
+== Process information ==
+*[[/Deposition of stoichiometric nitride using the 4" LPCVD nitride furnace|Deposition of stoichiometric nitride using the 4" LPCVD nitride furnace]]
+*[[/Deposition of low stress nitride using the 4" LPCVD nitride furnace|Deposition of low stress nitride using the 4" LPCVD nitride furnace <span style="color:Red">(Low stress nitride depositions are no longer available in this furnace - use the 6" nitride furnace instead)</span>]]
+*[[/Deposition of low stress nitride using the 6" LPCVD nitride furnace|Deposition of low stress nitride using the 6" LPCVD nitride furnace ]]
+*[[/Deposition of stoichiometric nitride using the 6" LPCVD nitride furnace|Deposition of stoichiometric nitride using the 6" LPCVD nitride furnace <span style="color:Red">(4" wafers need a special permission using as a back up of 4" LPCVD nitride furnace, B2)</span>]]
+*[[/Using LPCVD silicon nitride as a masking material for KOH etching|Using LPCVD silicon nitride as a masking material for KOH etching]]
+==Equipment performance and process related parameters==
+{| border="2" cellspacing="0" cellpadding="2"
+!colspan="2" border="none" style="background:silver; color:black;" align="center"|Equipment
+|style="background:WhiteSmoke; color:black"|<b>6" LPCVD nitride furnace (E3)</b>
+|style="background:WhiteSmoke; color:black"|<b>4" LPCVD nitride furnace (B2)</b>
+|-
+!style="background:silver; color:black;" align="center"|Purpose
+|style="background:LightGrey; color:black"|Deposition of
+|style="background:WhiteSmoke; color:black"|
+*Silicon rich (low stress) nitride
+*Stoichiometric nitride
+|style="background:WhiteSmoke; color:black"|
+*Stoichiometric nitride
+|-
+!style="background:silver; color:black" align="center" valign="center" rowspan="2"|Performance
+|style="background:LightGrey; color:black"|Step coverage
+|style="background:WhiteSmoke; color:black"|
+*Very good
+|style="background:WhiteSmoke; color:black"|
+*Very good
 |-
-|Film thickness
+|style="background:LightGrey; color:black"|Film quality
-|
+|style="background:WhiteSmoke; color:black"|
-*Si<sub>3</sub>N<sub>4</sub>:~50Å - ~3000Å
+*Deposition on both sides of the substrate
-*SRN: ~50Å - ~10000Å
+*Dense film
+*Few defects
+|style="background:WhiteSmoke; color:black"|
+*Deposition on both sides of the substrate
+*Dense film
+*Very few defects
 |-
-|Process Temperature
+!style="background:silver; color:black" align="center" valign="center" rowspan="3"|Process parameter range
-|
+|style="background:LightGrey; color:black"|Temperature
-*800-835 <sup>o</sup>C
+|style="background:WhiteSmoke; color:black"|
+*810-845 <sup>o</sup>C
+The temperature vary over the furnace tube
+|style="background:WhiteSmoke; color:black"|
+*780-790 <sup>o</sup>C
+The temperature vary over the furnace tube
 |-
-|Step coverage
+|style="background:LightGrey; color:black"|Pressure
-|
+|style="background:WhiteSmoke; color:black"|
-*Good
+*150 mTorr
+|style="background:WhiteSmoke; color:black"|
+*200 mTorr
 |-
-|Film quality
+|style="background:LightGrey; color:black"|Gas flows
-|
+|style="background:WhiteSmoke; color:black"|
-*Dense film
+For Low stress nitride
-*Few defects
+*Dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>): 200 sccm
+*Ammonia (NH<sub>3</sub>): 50 sccm
+For Stoichiometric nitride on 6" wafers
+*Dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>): 45 sccm
+*Ammonia (NH<sub>3</sub>): 180 sccm
+|style="background:WhiteSmoke; color:black"|
+*Dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>): 20 sccm
+*Ammonia (NH<sub>3</sub>): 80 sccm
+The gas flows depend on whether nitride is deposited on 4" or 6" wafers
 |-
-|Batch size
+!style="background:silver; color:black" align="center" valign="center" rowspan="3"|Substrates
-|
+|style="background:LightGrey; color:black"|Batch size
-*1-25 4" wafer per run
+|style="background:WhiteSmoke; color:black"|
-*deposition on both sides of the substrate
+*1-25 100 mm wafers
+*1-25 150 mm wafers
+Including a test wafer
+|style="background:WhiteSmoke; color:black"|
+*1-15 100 mm wafers
+Including a test wafer
 |-
-| Substrate material allowed
+| style="background:LightGrey; color:black"|Allowed materials
-|
+|style="background:WhiteSmoke; color:black"|
-*Silicon wafers
+*Silicon wafers (new or RCA cleaned)
 **with layers of silicon oxide or silicon (oxy)nitride
-*Quartz wafers
+**from the A, B and E stack furnaces
+*Quartz/fused silica wafers (RCA cleaned)
+|style="background:WhiteSmoke; color:black"|
+*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)
 |-
 |}
-==Process Knowledge==
+<!--hide text
-Please take a look at the process side for deposition of Silicon Nitride using LPCVD:
+==Using LPCVD silicon nitride as a masking material for KOH etching==
-[[Specific Process Knowledge/Thin film deposition/Deposition of Silicon Nitride/Deposition of Silicon Nitride using LPCVD|Deposition of Silicon Nitride using LPCVD]]
+Stoichiometric silicon nitride is mainly used as masking material for potassium hydroxide (KOH) etching. The etch rate of the nitride in 80 <sup>o</sup>C KOH is expected to be less than 1 Å/min.
+There are regularly users having problems with pinholes in the silicon nitride after KOH etching. It is not always clear what the reasons are, but we suspect problems can arise due to
+*too many or too large particles in the nitride.
+*too rough handling of the wafers after the nitride deposition.
+*too much stress between the nitride and the underlying layer.
+===Our recommendations to try and avoid pinhole problems are:===
+'''To avoid too many or too large particles in the nitride'''<br\>
+*If possible, use the new nitride furnace to deposit stoichiometric nitride. In order to avoid problems with particles it is not allowed to deposit low stress nitride in this furnace, and the particles level is therefore low compared to the older nitride furnace.
+*Before running a process keep in close contact with the Nanolab staff (especially the process specialist on the furnace) or take a look at the logbook to make sure that the nitride furnace is expected to be in a good state.
+'''To avoid too rough handling of the wafers after the nitride deposition'''<br\>
+*After the deposition handle the wafers with a clean glove on the edge of the wafers (no tweezers).
+*Be careful not to scratch wafers with nitride (e.g. up against each other or on the spinner or the aligner).
+*If you have nitride on the back side of a wafer while aligning, consider if you can protect it with e.g. a photoresist layer before loading it onto the aligner. Or use a non-vacuum aligner chuck with a big hole in the middle, so that the wafer is only laying on the edge. Avoid hard contact in the aligner if possible.
+'''To avoid too much stress between the nitride and the underlying layer'''<br\>
+*It is recommended to have a of silicon oxide layer between the silicon substrate and the nitride layer to reduce the stress level between the layers. The silicon nitride is then expected to have less tendency to break.
+hide text-->
+== Rules for storage and RCA cleaning of wafers to the B2 and E3 furnaces ==
+*[[Specific_Process_Knowledge/Thermal_Process/Storage_and_cleaning_of_wafer_to_the_A,_B,_C_and_E_stack_furnaces|Storage and cleaning of wafer to the B2 and E3 furnaces]]