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

Danchip has two LPCVD (Low Pressure Chemical Vapour Deposition) furnaces that are dedicated for deposition of silicon nitride: A 6" furnace (installed in 2008) for deposition of stoichiometric nitride on 100 mm and 150 mm wafers and a 4" furnace (installed in 1995) that is mainly used for deposition of silicon rich (i.e. low stress) nitride on 100 mm wafers. In LabManager the two furnaces are named "Furnace: LPCVD nitride (6") (E3)" and "Furnace: LPCVD nitride (4") (B2)", respectively. Both furnaces are Tempress horizontal furnaces.

Please be aware of that it is not allowed to deposit silicon rich nitride in the 6" nitride furnace to avoid problems with particles. The 4" nitride furnace is mainly dedicated for deposition of silicon rich nitride which does affect the cleanliness of the furnace. And 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 25 wafers (in the 6" nitride furnace) or 15 wafers (in the 4" nitride furnace) at a time. The deposition takes place under vacuum (120-200 mTorr, depending on the process) and at 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

Equipment performance and process related parameters

Equipment		4" LPCVD nitride furnace (B2)	6" LPCVD nitride furnace (E3)
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	830-845 ^oC The temperature vary over the furnace tube	780-790 ^oC The temperature very over the furnace tube
	Pressure	120 mTorr	200 mTorr
	Gas flows	Dichlorsilane (SiH₂Cl₂): 80 sccm Ammonia (NH₃): 20 sccm	Dichlorsilane (SiH₂Cl₂): 10-45 sccm Ammonia (NH₃): 160-180 sccm The gas flows depend on whether nitride is deposited on 4" or 6" wafers
Substrates	Batch size	1-15 100 mm wafers Including a test wafer	1-25 100 mm wafers 1-25 150 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)

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+'''Feedback to this page''': '''[mailto:thinfilm@danchip.dtu.dk?Subject=Feed%20back%20from%20page%http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Thin_film_deposition/Deposition_of_Silicon_Nitride/Deposition_of_Silicon_Nitride_using_LPCVD) click here]'''
-=<span style="background:#FF2800">THIS PAGE IS UNDER CONSTRUCTION</span>[[image:Under_construction.png|200px]]=
+[[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]]
+==Deposition of Silicon Nitride using LPCVD==
+Danchip has two LPCVD (Low Pressure Chemical Vapour Deposition) furnaces <!--[[Specific Process Knowledge/Thin film deposition/B2 Furnace LPCVD Nitride|LPCVD furnaces]]--> that are dedicated for deposition of silicon nitride: A 6" furnace (installed in 2008) for deposition of stoichiometric nitride on 100 mm and 150 mm wafers and a 4" furnace (installed in 1995) that is mainly used for deposition of silicon rich (i.e. low stress) nitride on 100 mm wafers. In LabManager the two furnaces are named "Furnace: LPCVD nitride (6") (E3)" and "Furnace: LPCVD nitride (4") (B2)", respectively. Both furnaces are Tempress horizontal furnaces.
+Please be aware of that it is not allowed to deposit silicon rich nitride in the 6" nitride furnace to avoid problems with particles. The 4" nitride furnace is mainly dedicated for deposition of silicon rich nitride which does affect the cleanliness of the furnace. And 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 25 wafers (in the 6" nitride furnace) or 15 wafers (in the 4" nitride furnace) at a time. The deposition takes place under vacuum (120-200 mTorr, depending on the process) and at 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.
-==LPCVD (Low Pressure Chemical Vapor Deposition) Silicon Nitride==
+'''The user manuals, quality control procedures and results, user APVs, technical information and contact information can be found in LabManager:'''
-[[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 6" furnace (installed in 2008) for deposition of stoichiometric nitride on 4" or 6" wafers and a 4" furnace (installed in 1995) for deposition of stoichiometric nitride and silicon rich (i.e. low stress) nitride on 4" wafers. In LabManager the two furnaces are named "Furnace: LPCVD nitride (6")" and "Furnace: LPCVD nitride", respectively. Please be aware of that it is not allowed to deposit silicon rich nitride in the 6" nitride furnace to avoid problems with particles. Both furnaces are Tempress horizontal furnaces.
-The LPCVD silicon nitride deposition is a batch process, where nitride can be deposited on a batch of up to 25 wafers (in the 6" nitride furnace) or 15 wafers (in the 4" nitride furnace) at a time. The deposition takes place at a temperature of 780-845 <sup>o</sup>C and a 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.
+[http://labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=84 4" LPCVD nitride furnace (B2)],
-At moment there is only a standard recipe for deposition of silicon rich nitride (SRN) on 4" wafers on the 4" nitride furnace. On the 6" 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.
+[http://labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=250 6" LPCVD nitride furnace (E3)]
-'''The user manuals, quality control procedures and results, technical information and contact information can be found in LabManager:'''
-'''[http://www.labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=84 LPCVD Nitride 100 mm furnace (B2)]'''
+<!--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-->
-'''[http://www.labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=250 LPCVD Nitride 150 mm furnace (E3)]'''
+== Process information ==
-==Process Knowledge==
+*[[/Deposition of low stress nitride using the 4" LPCVD nitride furnace|Deposition of low stress nitride using the 4" LPCVD nitride furnace]]
-Please take a look at the process side to get more information about deposition of silicon nitride using an LPCVD furnace:
+*[[/Deposition of stoichiometric nitride using the 6" LPCVD nitride furnace|Deposition of stoichiometric nitride using the 6" LPCVD nitride furnace]]
+*[[/Using LPCVD silicon nitride as a masking material for KOH etching|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]]
+==Equipment performance and process related parameters==
-==Overview of the performance of LPCVD Silicon Nitride and some process related parameters==
+{| border="2" cellspacing="0" cellpadding="2"
-{| border="2" cellspacing="0" cellpadding="0"
+!colspan="2" border="none" style="background:silver; color:black;" align="center"|Equipment
+|style="background:WhiteSmoke; color:black"|<b>4" LPCVD nitride furnace (B2)</b>
+|style="background:WhiteSmoke; color:black"|<b>6" LPCVD nitride furnace (E3)</b>
 |-
 !style="background:silver; color:black;" align="center"|Purpose
-|style="background:LightGrey; color:black"|Deposition of silicon nitride
+|style="background:LightGrey; color:black"|Deposition of
-|style="background:WhiteSmoke; color:black"|Stoichiometry:
+|style="background:WhiteSmoke; color:black"|
-*Si<sub>3</sub>N<sub>4</sub> (only 6" nitride furnace at the moment)
+*Silicon rich (low stress) nitride
-*SRN (only 4" nitride furnace, only 4" wafers)
+*(Stoichiometric nitride)
-Si<sub>3</sub>N<sub>4</sub>: Stoichiometric nitride
-SRN: Silicon rich nitride (low stress nitride)
-|-
-!style="background:silver; color:black" align="center" valign="center" rowspan="4"|Performance
-|style="background:LightGrey; color:black"|Film thickness
 |style="background:WhiteSmoke; color:black"|
-*Si<sub>3</sub>N<sub>4</sub>: ~0 - 1400Å
+*Stoichiometric nitride
-*SRN: ~ ~0 - 2800Å
-Thicker layers have to be deposited over more runs
 |-
+!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:LightGrey; color:black"|Nitride thickness uniformity
 |style="background:WhiteSmoke; color:black"|
-" nitride furnace (Si<sub>3</sub>N<sub>4</sub>):
+*Deposition on both sides of the substrate
-*Uniformity within wafer: <2.5 %
+*Dense film
-*Wafer-to-wafer uniformity: <4.5 %
+*Very few defects
-*Run-to-run uniformity: <3 %
-" nitride furnace (SRN):
-*Uniformity within wafer: <2.5 %
-*Wafer-to-wafer uniformity: <6 %
-*Run-to-run uniformity: <3 %
 |-
 !style="background:silver; color:black" align="center" valign="center" rowspan="3"|Process parameter range
-|style="background:LightGrey; color:black"|Process Temperature
+|style="background:LightGrey; color:black"|Temperature
+|style="background:WhiteSmoke; color:black"|
+*830-845 <sup>o</sup>C
+The temperature vary over the furnace tube
 |style="background:WhiteSmoke; color:black"|
-" nitride furnace (Si<sub>3</sub>N<sub>4</sub>):
 *780-790 <sup>o</sup>C
-*The process temperature vary over the furnace tube
+The temperature very over the furnace tube
-" nitride furnace (SRN):
-*830-845 <sup>o</sup>C
-*The process temperature vary over the furnace tube
 |-
-|style="background:LightGrey; color:black"|Process pressure
+|style="background:LightGrey; color:black"|Pressure
+|style="background:WhiteSmoke; color:black"|
+*120 mTorr
 |style="background:WhiteSmoke; color:black"|
-" nitride furnace (Si<sub>3</sub>N<sub>4</sub>):
 *200 mTorr
-" nitride furnace (SRN):
-*120 mTorr
 |-
 |style="background:LightGrey; color:black"|Gas flows
 |style="background:WhiteSmoke; color:black"|
-" nitride furnace (Si<sub>3</sub>N<sub>4</sub>):
-*Dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>): 30-33 sccm
-*Ammonia (NH<sub>3</sub>): 100-120 sccm
-*The gas flows depend on whether nitride is deposited on 4" or 6" wafers
-" nitride furnace (SRN):
 *Dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>): 80 sccm
 *Ammonia (NH<sub>3</sub>): 20 sccm
+|style="background:WhiteSmoke; color:black"|
+*Dichlorsilane (SiH<sub>2</sub>Cl<sub>2</sub>): 10-45 sccm
+*Ammonia (NH<sub>3</sub>): 160-180 sccm
+The gas flows depend on whether nitride is deposited on 4" or 6" wafers
 |-
-!style="background:silver; color:black" align="center" valign="center" 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"|
-" nitride furnace:
+*1-15 100 mm wafers
-*1-25 4" or 6" wafers per run
+Including a test wafer
-" nitride furnace:
+|style="background:WhiteSmoke; color:black"|
-*1-15 4" wafers per run
+*1-25 100 mm wafers
+*1-25 150 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 or RCA cleaned wafers)
+*Silicon wafers (new or 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
-*Pure quartz (fused silica) 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==
+At Danchip 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 Danchip 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-->