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: @@
-==LPCVD (Low Pressure Chemical Vapor Deposition) Silicon Nitride==
+'''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]'''
-[[image:DC_nyhed_3.jpg|300x300px|right|thumb|6´´ LPCVD nitride furnace (new nitride furnace) positioned in cleanroom 14]]
-[[image:Furnace_nitride1.jpg|300x300px|right|thumb|LPCVD nitride furnace (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 an older furnace (installed in 1995) for deposition of low stress (i.e. silicon rich) 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 nitride can be deposited on a batch of up to 17 wafers (in the old nitride furnace) or 25 wafers (in the new nitride furnace) at a time. The deposition takes place at temperatures of 780-845 degrees Celsius and at pressure of 120-200 mTorr. 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.
+<i> Unless otherwise stated, this page is written by <b>DTU Nanolab internal</b></i>
-On the old nitride furnace there are one standard recipe for deposition of low stress nitride (SRN) on 4" wafers. On the new nitride furnace there are two standard recipes for deposition of stoichiometric nitride (Si<sub>3</sub>N<sub>4</sub>), one for 4" wafers and one for 6" wafers.
+[[Category: Equipment|Thin film F]]
+[[Category: Thin Film Deposition|LPCVD nitride]]
+[[Category: Furnaces|LPCVD nitride]]
-To get information on how to operate the furnaces please read the user manuals which are uploaded to LabManager on the machine page or consult the Furnace group at Danchip (furnace@danchip.dtu.dk).
+[[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]]
-==Process Knowledge==
-Please take a look at the process side to get more information about deposition of Silicon Nitride using LPCVD:
-[[Specific Process Knowledge/Thin film deposition/Deposition of Silicon Nitride/Deposition of Silicon Nitride using LPCVD|Deposition of Silicon Nitride using LPCVD]]
-<br clear="all" />
+==Deposition of Silicon Nitride using LPCVD==
-==Overview of the performance of LPCVD Silicon Nitride and some process related parameters==
+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:
+*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.
-{| border="2" cellspacing="0" cellpadding="10"
+Please check the cross contamination information in LabManager before you use any of the two furnaces.
-|-
-!style="background:silver; color:black;" align="left"|Purpose
+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>).
-|style="background:LightGrey; color:black"|Deposition of silicon nitride
-|style="background:WhiteSmoke; color:black"|Stoichiometry:
+The LPCVD nitride has a very good step coverage, and the film thickness is very uniform over the wafers.
-*Si<sub>3</sub>N<sub>4</sub>
-*SRN (old nitride furnace, only 4" wafers)
-Si<sub>3</sub>N<sub>4</sub>: Stoichiometric nitride
+'''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"
-SRN: Silicon rich nitride (low stress nitride)
+!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="left" valign="top" rowspan="4"|Performance
+!style="background:silver; color:black;" align="center"|Purpose
-|style="background:LightGrey; color:black"|Film thickness
+|style="background:LightGrey; color:black"|Deposition of
 |style="background:WhiteSmoke; color:black"|
-*Si<sub>3</sub>N<sub>4</sub>: ~50Å - ~3000Å
+*Silicon rich (low stress) nitride
-*SRN: ~50Å - ~10000Å
+*Stoichiometric nitride
-Thick layers have to be deposited over more runs
+|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"|
-*Good
+*Very good
+|style="background:WhiteSmoke; color:black"|
+*Very good
 |-
 |style="background:LightGrey; color:black"|Film quality
 |style="background:WhiteSmoke; color:black"|
 *Deposition on both sides of the substrate
 *Dense film
 *Few defects
+|style="background:WhiteSmoke; color:black"|
+*Deposition on both sides of the substrate
+*Dense film
+*Very few defects
 |-
-|style="background:LightGrey; color:black"|Nitride thickness uniformity
+!style="background:silver; color:black" align="center" valign="center" rowspan="3"|Process parameter range
+|style="background:LightGrey; color:black"|Temperature
+|style="background:WhiteSmoke; color:black"|
+*810-845 <sup>o</sup>C
+The temperature vary over the furnace tube
 |style="background:WhiteSmoke; color:black"|
-New nitride furnace:
+*780-790 <sup>o</sup>C
-*Uniformity within wafer: <3 %
+The temperature vary over the furnace tube
-*Wafer-to-wafer uniformity: <3 %
-*Run-to-run uniformity: <3 %
-Old nitride furnace:
-*Uniformity within wafer: <1.3 %
-*Wafer-to-wafer uniformity: <4%
-*Run-to-run uniformity:
 |-
-!style="background:silver; color:black" align="left" valign="top" rowspan="3"|Process parameter range
+|style="background:LightGrey; color:black"|Pressure
-|style="background:LightGrey; color:black"|Process Temperature
 |style="background:WhiteSmoke; color:black"|
-*780-835 <sup>o</sup>C
+*150 mTorr
-The process temperature depends on the actual process
-|-
-|style="background:LightGrey; color:black"|Process pressure
 |style="background:WhiteSmoke; color:black"|
-*80-230 mTorr
+*200 mTorr
-The process pressure depends on the actual process
 |-
 |style="background:LightGrey; color:black"|Gas flows
 |style="background:WhiteSmoke; color:black"|
-*Dichlorsilane (SiH<math>_2</math>Cl<math>_2</math>): 10-120 sccm
+For Low stress nitride
-*Ammonia (NH<math>_3</math>): 10-75 sccm
+*Dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>): 200 sccm
-The gas flows depend on the actual process
+*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
 |-
-!style="background:silver; color:black" align="left" valign="top" rowspan="2"|Substrates
+!style="background:silver; color:black" align="center" valign="center" rowspan="3"|Substrates
 |style="background:LightGrey; color:black"|Batch size
 |style="background:WhiteSmoke; color:black"|
-New nitride furnace:
+*1-25 100 mm wafers
-*1-25 4" or 6" wafers per run
+*1-25 150 mm wafers
-Old nitride furnace:
+Including a test wafer
-*1-35 4" wafers per run
+|style="background:WhiteSmoke; color:black"|
-The number of wafers depends on the size of the quartz boat
+*1-15 100 mm wafers
+Including a test wafer
 |-
-| style="background:LightGrey; color:black"|Substrate material allowed
+| style="background:LightGrey; color:black"|Allowed materials
 |style="background:WhiteSmoke; color:black"|
-*Silicon wafers (new wafers from a new box or RCA cleaned wafers)
+*Silicon wafers (new or RCA cleaned)
-**with layers of silicon oxide or silicon (oxy)nitride (RCA cleaned)
+**with layers of silicon oxide or silicon (oxy)nitride
-**from furnaces in stack A or B in cleanroom 2
+**from the A, B and E stack furnaces
-*Quartz wafers (RCA cleaned)
+*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)
 |-
 |}
+<!--hide text
+==Using LPCVD silicon nitride as a masking material for KOH etching==
+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]]