Specific Process Knowledge/Thin film deposition/Deposition of Silicon Nitride: Difference between revisions

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Deposition of Silicon Nitride can be done with either LPCVD or PECVD.
'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php?title=Specific_Process_Knowledge/Thin_film_deposition/Deposition_of_Silicon_Nitride&action=submit click here]'''
 
<i> Unless otherwise stated, this page is written by <b>DTU Nanolab internal</b></i>
 
== Deposition of silicon nitride ==
Deposition of silicon nitride can be done by either LPCVD (Low Pressure Chemical Vapor Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition). Stoichiometric nitride or silicon rich (low stress) LPCVD nitride is deposited on a batch of wafers in a LPCVD nitride furnace. PECVD nitride (or oxynitride) is deposited on a few samples at a time in a PECVD system. LPCVD nitride has a good step coverage and a very good uniformity. Using PECVD it is possible to deposit a much lower temperature and a thicker layer of nitride on different types of samples, but the nitride does not cover sidewalls very well.
 
It is also possible to deposit silicon nitride and oxynitride by reactive sputtering.
 
*[[Specific Process Knowledge/Thin film deposition/Furnace LPCVD Nitride/Deposition of stoichiometric nitride using the 4" LPCVD nitride furnace|Deposition of stoichiometric nitride using the 4" LPCVD nitride furnace]]
*[[Specific Process Knowledge/Thin film deposition/Furnace LPCVD Nitride/Deposition of low stress nitride using the 6" LPCVD nitride furnace|Deposition of silicon rich (low stress) nitride using the 6" LPCVD nitride furnace]]
 
*[[/Deposition of Silicon Nitride using PECVD|Nitride deposition using PECVD]] (''or oxynitride'')
 
*[[/Deposition of silicon nitride using Lesker sputter system|Nitride deposition using Lesker sputter system]]
 
*[[/Deposition of silicon nitride using Sputter-System Metal-Oxide(PC1)|Nitride deposition using Sputter-System Metal-Oxide(PC1)]]
 
==Comparison of LPCVD, PECVD, and sputter systems for silicon nitride deposition==
 
{|border="1" cellspacing="1" cellpadding="3" style="text-align:left;"
|-
 
|-
|-style="background:silver; color:black"
!
![[Specific Process Knowledge/Thin film deposition/Furnace LPCVD Nitride|LPCVD]]
![[Specific Process Knowledge/Thin film deposition/PECVD|PECVD]]
![[Specific_Process_Knowledge/Thin_film_deposition/Cluster-based_multi-chamber_high_vacuum_sputtering_deposition_system|Sputter-System Metal-Nitride(PC3) and Sputter-System Metal-Oxide(PC1)]]
![[Specific Process Knowledge/Thin film deposition/Lesker|Lesker sputter system]]
|-
 
|-
|-style="background:WhiteSmoke; color:black"
!Generel description
|
*Low Pressure Chemical Vapour Deposition (LPCVD furnace process)
|
*Plasma Enhanced Chemical Vapour Deposition (PECVD process)
|
*Reactive sputtering
*Pulsed DC reactive sputtering
*Reactive HIPIMS (high-power impulse magnetron sputtering)
|*Reactive sputtering
|-
 
|-
|-style="background:LightGrey; color:black"
!Stoichiometry
|
*Stoichiometric nitride, Si<sub>3</sub>N<sub>4</sub>
*Silicon rich (low stress) nitride, SRN
|
*Si<sub>x</sub>N<sub>y</sub>H<sub>z</sub>
*Si<sub>x</sub>O<sub>y</sub>N<sub>z</sub>H<sub>v</sub>
Silicon nitride can be doped with boron or phosphorus
|
*Si<sub>x</sub>N<sub>y</sub> (Sputter-System Metal-Nitride(PC3))
*Si<sub>x</sub>O<sub>y</sub>N<sub>z</sub> (Sputter-System Metal-Oxide(PC1))
Tunable composition
|
*Unknown
|-
 
|-
|-style="background:WhiteSmoke; color:black"
!Film thickness
|
*Stoichiometric nitride: ~5 nm - ~230 nm
*Silicon rich (low stress) nitride: ~5 nm - ~335 nm
Thicker nitride layers can be deposited over more runs (maximum two)
|
*~40 nm - 10 µm
|
*limited by process time.
*Deposition rate likely faster than Sputter-System (Lesker)
 
|
*limited by process time.
*Deposition rate ~ 1-5 nm/min
|-
 
|-
|-style="background:LightGrey; color:black"
!Process temperature
|
*Stoichiometric nitride: 780 °C - 800 °C
*Silicon rich (low stress) nitride: 810 °C - 845 °C
|
*300 °C
|
*Up to 600 °C
|
*Up to 400 °C
|-
 
|-
|-style="background:WhiteSmoke; color:black"
!Step coverage
|
*Good
|
*Less good
|
*some step coverage possible, especially by HIPIMS
|
*some step coverage possible but amount unknown
|-
 
|-
|-style="background:LightGrey; color:black"
!Film quality
|
*Deposition on both sides og the substrate
*Dense film
*Few defects
|
*Deposition on one side of the substrate
*Less dense film
*Incorporation of hydrogen in the film
|
*Deposition on one side of the substrate
*Less dense film
*Properties including density tunable (requires process development)
|
*Deposition on one side of the substrate
*unknown quality
*likely O-contamination
|-
 
|-
|-style="background:WhiteSmoke; color:black"
!KOH etch rate (80 <sup>o</sup>C)
|
*Expected <1 Å/min
|
*Dependent on recipe: ~1-10 Å/min
|
*Unknown
|
*Unknown
|-
 
|-
|-style="background:LightGrey; color:black"
!BHF etch rate
|
*Very low ([[Specific_Process_Knowledge/Etch/Etching_of_Silicon_Nitride|more info here]])
|
*Very high compared the LPCVD nitride ([[Specific_Process_Knowledge/Etch/Etching_of_Silicon_Nitride|more info here]])
|
*Unknown
|
*Unknown
|-
 
|-
|-style="background:WhiteSmoke; color:black"
!Batch size
|
*1-15 100 mm wafers (4" furnace), 1-25 100 mm wafers (6" furnace)
*1-25 150 mm wafers (only 6" furnace)
|
*Several smaller samples
*1-7 50 mm wafers
*1 100 mm wafers
*1 150 mm wafer
Depending on what PECVD you use
|
*many smaller samples
*Up to 10*100 mm or 150 mm wafers
|
*Several smaller samples
*1-several 50 mm wafers
*1*100 mm wafers
*1*150 mm wafer
|-
 
|-
|-style="background:LightGrey; color:black"
!'''Allowed materials'''
|
*Silicon
*Silicon oxide
*Silicon nitride
*Pure quartz (fused silica)
Processed wafers have to be RCA cleaned
|
*Silicon
*Silicon oxide (with boron, phosphorous)
*Silicon nitrides (with boron, phosphorous)
*Pure quartz (fused silica)
*III-V materials (in PECVD4)
*Small amount of metals (in PECVD3)
|
*Almost any as long as they do not outgas and are not very toxic, see cross-contamination sheets
|
*Any
|-
|}
 
<br clear="all" />
 
 
 
 
 
 
<!--
Deposition of Silicon Nitride can be done with either LPCVD (Low Pressure Chemical Vapor Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition).


==Deposition of Silicon Nitride using LPCVD==
==Deposition of Silicon Nitride using LPCVD==
LPCVD nitride can be made in the [[Specific Process Knowledge/Thin film deposition/B2 Furnace LPCVD Nitride|LPCVD nitride furnace]]. It is a batch process meaning you can run a batch of 25 wafers at a time. The deposition takes place at temperatures of 800-850 degrees Celsius. 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 low stress nitride (SNR).
LPCVD silicon nitride can be deposited in a [[Specific Process Knowledge/Thin film deposition/B2 Furnace LPCVD Nitride|LPCVD nitride furnace]]. DTU Nanolab has two LPCVD nitride furnaces: A new furnace (installed in 2008) for deposition of stoichiometric nitride on 4" or on 6" wafers and an older furnace (installed in 1995) for deposition of stoichiometric nitride and low stress nitride on 4" wafers.
 
The LPCVD nitride deposition is a batch process, meaning that nitride can be deposited on a batch of up to 15 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 a pressure of 120-200 mTorr. The LPCVD silicon nitride has a good step coverage, and the film thickness is very uniform over the wafers. On the furnaces there are standard processes for deposition of stoichiometric nitride (Si<sub>3</sub>N<sub>4</sub>) and for deposition of low stress nitride (SRN) (only on the old nitride furnace).
*[[/Deposition of Silicon Nitride using LPCVD|Deposition of Silicon Nitride using LPCVD]]


==Deposition of Silicon Nitride using PECVD==
==Deposition of Silicon Nitride using PECVD==
PECVD nitride and oxynitride can be deposited in one of the [[Specific Process Knowledge/Thin film deposition/PECVD|PECVD]] systems. You can run 1-3 wafers at a time depending on which one of the PECVD's you use. The deposition takes place at 300 degrees Celcius. This can be of importance for some applications but it gives a less dense film and the stoichiometry is on the following form: Si<sub>x</sub>N<sub>y</sub>O<sub>z</sub>H<sub>v</sub>. The step coverage and thickness uniformity of the film is not as good as for the LPCVD nitride. In one of our PECVD systems (PECVD3) we allow small amounts of metal on the wafers entering the system, this is not allowed in the LPCVD and in the other PECVD (PECVD1).
PECVD nitride and oxynitride can be deposited in one of the [[Specific Process Knowledge/Thin film deposition/PECVD|PECVD]] systems at DTU Nanolab. You can run 1-3 wafers on several smaller chips at a time depending on which one of the PECVD's you use. The deposition takes place at 300 degrees Celsius. This can be of importance for some applications, but it gives a less dense film compared to LPCVD nitride, and the stoichiometry is on the following form: Si<sub>x</sub>N<sub>y</sub>O<sub>z</sub>H<sub>v</sub>. The step coverage and the thickness uniformity of the film are not as good as for the LPCVD nitride. In one of our PECVD systems (PECVD3) we allow small amounts of metal on the wafers entering the system; this is not allowed in the LPCVD furnace and in the clean PECVD (PECVD1). We also have a PECVD for deposition on III-V materials (PECVD2).
*[[/Deposition of Silicon Nitride using PECVD|Deposition of Silicon Nitride using PECVD]] - ''or oxynitride''


==Comparison of LPCVD and PECVD for silicon nitride deposition==
==Comparison of LPCVD and PECVD for silicon nitride deposition==
{| border="1" cellspacing="0" cellpadding="3" align="center"
{| border="1" cellspacing="0" cellpadding="3" align="center"
!  
!  
! LPCVD
! [[Specific Process Knowledge/Thin film deposition/Furnace LPCVD Nitride|LPCVD]]
! PECVD
! [[Specific Process Knowledge/Thin film deposition/PECVD|PECVD]]
|-  
|-  
| Stoichiometry
| Stoichiometry
|
|
*Si<sub>3</sub>N<sub>4</sub>
*Si<sub>3</sub>N<sub>4</sub>
*SRN
*SRN (only old nitride furnace, only 4" wafers)
SRN: Silicon Rich Nitride
Si<sub>3</sub>N<sub>4</sub>: Stoichiometric nitride
 
SRN: Silicon rich nitride (low stress nitride)
|
|
*Si<sub>x</sub>N<sub>y</sub>H<sub>z</sub>
*Si<sub>x</sub>N<sub>y</sub>H<sub>z</sub>
*Si<sub>x</sub>O<sub>y</sub>N<sub>z</sub>H<sub>v</sub>
*Si<sub>x</sub>O<sub>y</sub>N<sub>z</sub>H<sub>v</sub>
Can be doped with boron, phosphorus or germanium
Silicon nitride can be doped with boron, phosphorus or germanium
|-
|-
|Film thickness
|Film thickness
|
|
*Si<sub>3</sub>N<sub>4</sub>:~50Å - ~3000Å
*Si<sub>3</sub>N<sub>4</sub>: ~50 Å - ~1400 Å
*SRN: ~50Å - ~10000Å
*SRN: ~50 Å - ~2800 Å
Thicker nitride layers can be deposited over more runs
|
|
*~40nm - 10µm
*~40 nm - 10 µm
|-
|-
|Process Temperature
|Process temperature
|
|
*800-835 <sup>o</sup>C
*780 <sup>o</sup>C - 845 <sup>o</sup>C
|
|
*300 <sup>o</sup>C
*300 <sup>o</sup>C
Line 44: Line 261:
|Film quality
|Film quality
|
|
*Deposition on both sides of the substrate
*Dense film
*Dense film
*Few defects
*Few defects
|
|
*Deposition on one side of the substrate
*Less dense film
*Less dense film
*Incorporation of hydrogen in the film
*Incorporation of hydrogen in the film
Line 52: Line 271:
|Batch size
|Batch size
|
|
*1-25 4" wafer per run
Old nitride furnace:
*deposition on both sides of the substrate
*1-17 4" wafers per run  
New nitride furnace:
*1-25 4" or 6" wafers per run
|
|
*1-3 4" wafers or 1 6" wafer or many smaller chips per run
*1-3 4" wafers or one 6" wafer or many smaller chips per run
*deposition on one side of the substrate
|-
|-
| Substrate material allowed
| Substrate materials allowed
|
*Silicon wafers (new wafers 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
*Pure quartz (fused silica) wafers (RCA cleaned)
|
|
*Silicon wafers
*Silicon wafers
**with layers of silicon oxide or silicon (oxy)nitride
**with layers of silicon oxide or silicon (oxy)nitride
*Quartz wafers
*Quartz wafers
|
*Small amounts of metal < 5% of the wafer coverage (ONLY in PECVD3!)
*Silicon
**with layers of silicon oxide or silicon (oxy)nitride
*Quartz
*Small amount of metal (in PECVD3)
|-  
|-  
| Etch rate in 80 <sup>o</sup>C KOH
|Expected <1 Å/min
|Dependent on recipe: ~1-10 Å/min
|-
| Etch rate in BHF
|Very low
|Very high compared to the etch rate of LPCVD nitride
|-
|}
|}
 
-->
==Choose deposition technique==
*[[/Deposition of Silicon Nitride using LPCVD|Deposition of Silicon Nitride using LPCVD]]
*[[/Deposition of Silicon Nitride using PECVD|Deposition of Silicon Nitride using PECVD]] - ''or oxynitride''

Latest revision as of 10:12, 11 May 2023

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Unless otherwise stated, this page is written by DTU Nanolab internal

Deposition of silicon nitride

Deposition of silicon nitride can be done by either LPCVD (Low Pressure Chemical Vapor Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition). Stoichiometric nitride or silicon rich (low stress) LPCVD nitride is deposited on a batch of wafers in a LPCVD nitride furnace. PECVD nitride (or oxynitride) is deposited on a few samples at a time in a PECVD system. LPCVD nitride has a good step coverage and a very good uniformity. Using PECVD it is possible to deposit a much lower temperature and a thicker layer of nitride on different types of samples, but the nitride does not cover sidewalls very well.

It is also possible to deposit silicon nitride and oxynitride by reactive sputtering.

Comparison of LPCVD, PECVD, and sputter systems for silicon nitride deposition

LPCVD PECVD Sputter-System Metal-Nitride(PC3) and Sputter-System Metal-Oxide(PC1) Lesker sputter system
Generel description
  • Low Pressure Chemical Vapour Deposition (LPCVD furnace process)
  • Plasma Enhanced Chemical Vapour Deposition (PECVD process)
  • Reactive sputtering
  • Pulsed DC reactive sputtering
  • Reactive HIPIMS (high-power impulse magnetron sputtering)
 *Reactive sputtering
Stoichiometry
  • Stoichiometric nitride, Si3N4
  • Silicon rich (low stress) nitride, SRN
  • SixNyHz
  • SixOyNzHv

Silicon nitride can be doped with boron or phosphorus

  • SixNy (Sputter-System Metal-Nitride(PC3))
  • SixOyNz (Sputter-System Metal-Oxide(PC1))

Tunable composition

  • Unknown
Film thickness
  • Stoichiometric nitride: ~5 nm - ~230 nm
  • Silicon rich (low stress) nitride: ~5 nm - ~335 nm

Thicker nitride layers can be deposited over more runs (maximum two)

  • ~40 nm - 10 µm
  • limited by process time.
  • Deposition rate likely faster than Sputter-System (Lesker)
  • limited by process time.
  • Deposition rate ~ 1-5 nm/min
Process temperature
  • Stoichiometric nitride: 780 °C - 800 °C
  • Silicon rich (low stress) nitride: 810 °C - 845 °C
  • 300 °C
  • Up to 600 °C
  • Up to 400 °C
Step coverage
  • Good
  • Less good
  • some step coverage possible, especially by HIPIMS
  • some step coverage possible but amount unknown
Film quality
  • Deposition on both sides og the substrate
  • Dense film
  • Few defects
  • Deposition on one side of the substrate
  • Less dense film
  • Incorporation of hydrogen in the film
  • Deposition on one side of the substrate
  • Less dense film
  • Properties including density tunable (requires process development)
  • Deposition on one side of the substrate
  • unknown quality
  • likely O-contamination
KOH etch rate (80 oC)
  • Expected <1 Å/min
  • Dependent on recipe: ~1-10 Å/min
  • Unknown
  • Unknown
BHF etch rate
  • Unknown
  • Unknown
Batch size
  • 1-15 100 mm wafers (4" furnace), 1-25 100 mm wafers (6" furnace)
  • 1-25 150 mm wafers (only 6" furnace)
  • Several smaller samples
  • 1-7 50 mm wafers
  • 1 100 mm wafers
  • 1 150 mm wafer

Depending on what PECVD you use

  • many smaller samples
  • Up to 10*100 mm or 150 mm wafers
  • Several smaller samples
  • 1-several 50 mm wafers
  • 1*100 mm wafers
  • 1*150 mm wafer
Allowed materials
  • Silicon
  • Silicon oxide
  • Silicon nitride
  • Pure quartz (fused silica)

Processed wafers have to be RCA cleaned

  • Silicon
  • Silicon oxide (with boron, phosphorous)
  • Silicon nitrides (with boron, phosphorous)
  • Pure quartz (fused silica)
  • III-V materials (in PECVD4)
  • Small amount of metals (in PECVD3)
  • Almost any as long as they do not outgas and are not very toxic, see cross-contamination sheets
  • Any





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