Specific Process Knowledge/Lithography/Coaters/Spin Coater: Gamma UV processing: Difference between revisions

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'''Feedback to this page''': '''[mailto:labadviser@danchip.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Lithography/Coaters/Spin_Coater:_Gamma_UV_processing click here]'''
{{:Specific Process Knowledge/Lithography/authors_generic}}


=<span style="background:#FF2800">THIS PAGE IS UNDER CONSTRUCTION</span>[[image:Under_construction.png|200px]]=
'''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/Lithography/Coaters/Spin_Coater:_Gamma_UV_processing click here]'''
 
[[Category: Equipment|Lithography]]
[[Category: Lithography]]
 
__TOC__


=General Process Information=
=General Process Information=
Line 8: Line 13:
*Spin coating
*Spin coating
*Soft baking
*Soft baking
'''Features of Spin Coater: Gamma UV:'''
 
 
'''Features of Spin Coater: Gamma UV'''
*Cassette-to-cassette wafer handling
*Cassette-to-cassette wafer handling
*In-line HMDS priming  
*In-line HMDS priming  
Line 15: Line 22:
The process of HMDS priming on Spin Coater: Gamma UV consists of five steps:
The process of HMDS priming on Spin Coater: Gamma UV consists of five steps:
*Dehydration
*Dehydration
*HMDS filling
*HMDS injection
*Reaction
*Reaction
*Purging
*Purging
*Cooling
*Cooling
'''UPDATE from here:''' The wafer is first baked in contact with the hotplate in order to heat the wafer to the hotplate temperature. The hotplates of the priming modules are set to 50°C. Then the wafer is baked under a low vacuum (~0.5 bar) in order to dehydrate the wafer before HMDS application. The HMDS is applied to the wafer using nitrogen as a carrier gas. 15 liters per minute of dry nitrogen is bubbled through liquid HMDS before flowing across the wafer surface. After the priming, the chamber is pump-purged twice, using a 7s pump to ~0.5 bar and a 10s nitrogen purge at 40 liters per minute. Finally, the wafer is cooled on the priming module coolplate.


The contact angle after HMDS priming is a function of the priming temperature, the priming time, and the surface condition of the wafer. Tests have shown the contact angle to decrease with increasing hotplate temperature, while it increases as a function of priming time at constant temperature. At a priming temperature of 50°C, the contact angle resulting from priming an oxidized silicon wafer for t = 30 - 300s may be approximated by


<math>\theta = 95 - 119.2 * t^{-0.51}</math>
The top and bottom heaters of the VPO module are typically set to 120°C. The wafer is baked under a low vacuum (~0.35 bar) in order to heat and dehydrate the wafer before HMDS application. The HMDS is injected into the process chamber using nitrogen as a carrier gas. 10 liters per minute of dry nitrogen is bubbled through liquid HMDS before flowing into the chamber. The injection lasts until ambient pressuer is reached in the chamber. After the reaction time, the chamber is purged using nitrogen. Finally, the wafer is cooled on the cool plate.


The condition of the substrate surface is again a function of the substrate type, the substrate history, and the vacuum baking temperature and time. Since the vapor pressure of water at 50°C (0.123 bar) is lower than the vacuum bake pressure of 0.5 bar, the degree of dehydration will be a function of the vacuum baking time. Thus, for thick oxides, the standard of 30s vacuum bake may not be enough to dehydrate the surface sufficiently.
The contact angle after HMDS priming is a function of the priming temperature, the priming time, and the surface condition of the wafer. The condition of the substrate surface is again a function of the substrate type, the substrate history, and the effectiveness of the dehydration step. Since the vapor pressure of water at the chamber temperature is much higher than the dehydration pressure, similarly the boiling point of water at the dehydration pressure is well below the chamber temperature, the dehydration can probably be considered to be quite effective. However, for thick oxides, transport effects may cause the 30s dehydration time to be insufficient to dehydrate the surface sufficiently.


==Spin coating==
==Spin coating==
The process of spin coating on Spin Track 1 + 2 consists of a selection of the following steps:
The process of spin coating on Spin Coater: Gamma UV consists of a selection of the following steps:
*Acceleration to a low spin speed if dynamic dispense is used
*Acceleration to a low spin speed if dynamic dispense is used
*Resist dispense
*Resist dispense
*Resist spreading at low spin speed
*Spin-off
*Spin-off
*Deceleration before stop or further process steps
*Edge-bead removal using PGMEA
*Backside rinse using PGMEA
*Backside rinse using PGMEA


The wafer is first centered on the spindle chuck and held in place by vacuum. If static dispense is specified in the process, the spindle remains static during the ensuing resist dispense. In the case of dynamic dispense, the spindle is accelerated to a low spin speed before the resist is dispensed. Using too high spin speed during dispense can cause surface wetting issues, while a too low spin speed causes the resist to flow onto the backside of the wafer. The resist is dispensed through the dispense arm, positioned over the center of the wafer. The resist pump administers a fixed volume of resist (4 ml), but multiple dispenses may be used. After dispense, a short spin at low spin speed may be used in order to spread the resist over the wafer surface before spin-off.


The spin-off cycle determines the thickness of the resist coating. The thickness is primarily a function of the spin-off speed and the spin-off time, both following an inverse power-law (y=k*x^-a). The acceleration to the spin-off speed also influences the thickness, but the effect is dependent on previous steps. The spin-off is usually a simple spin at one speed, but it may be comprised of several steps at different spin speeds. After spin-off, the wafer is decelerated.
The wafer is first centered on the spindle chuck and held in place by vacuum. If static dispense is specified in the process, the spindle remains static during the ensuing resist dispense. In the case of dynamic dispense, the spindle is accelerated to a low spin speed before the resist is dispensed. Using too high spin speed during dispense can cause surface wetting issues, while a too low spin speed causes the resist to flow onto the backside of the wafer. The resist is dispensed through the dispense arm, positioned over the center of the wafer. The resist pump administers a volume of resist which depends on the substrate size.


During spin coating, resist builds up at the edge of the wafer due to the change in surface tension at the edge. This phenomenon is called an edge-bead. Dependent on spin coating parameters, the coating may be several times thicker at the edge than in the central area. In a subsequent hard contact exposure step, this edge-bead induces an undesired proximity gap which reduces the lateral resolution, and may even cause the wafer to stick to the mask. In an edge-bead removal step, solvent administered through a nozzle positioned at the edge of the wafer while spinning at low or medium spin speed dissolves the resist and washes it away. After the removal, a short spin at medium spin speed dries the wafer before the soft bake. Dependent on the viscosity (solvent content) of the resist at the point of edge-bead removal, this drying spin may cause the resist to re-flow and create a secondary edge-bead. In some cases, it may be necessary to (partially) soft bake the resist before edge-bead removal.
The spin-off cycle determines the thickness of the resist coating. The thickness is primarily a function of the spin-off speed and the spin-off time, both following an inverse power-law. The acceleration to the spin-off speed also influences the thickness, but the effect is dependent on previous steps. The spin-off is usually a simple spin at one speed, but it may be comprised of several steps at different spin speeds. After spin-off, the wafer is decelerated.


Dependent on the spin speeds used in the various steps of the spin coating, resist may creep over the edge of the wafer and onto the backside. Also, some resists tend to leave fine strings of resist protruding from the edge of the wafer, or folded onto the backside, an effect sometimes referred to as "cotton candy". This resist will contaminate the soft bake hotplate, and thus subsequent wafers with resist. In a backside rinse step, solvent administered through a nozzle to the backside of the wafer while spinning at low or medium spin speed dissolves the resist and washes it away. After the rinse, a short spin at medium spin speed dries the wafer before the soft bake. During the backside rinse solvent inevitably creeps onto the front side of the wafer. This effect may be used to dissolve and subsequently remove an edge-bead, but it may also leave the rim of the wafer exposed. As an alternative to backside rinse, a wafer which is left dirty on the backside by the spin coat process may be soft baked in proximity in order to protect the hotplate from contamination. This leaves front side coating intact, but also leaves the backside dirty.
Dependent on the spin speeds used in the various steps of the spin coating, resist may creep over the edge of the wafer and onto the backside. Also, some resists tend to leave fine strings of resist protruding from the edge of the wafer, or folded onto the backside, an effect sometimes referred to as "cotton candy". This resist will contaminate the soft bake hotplate, and thus subsequent wafers with resist. In a backside rinse step, solvent administered through a nozzle to the backside of the wafer while spinning dissolves the resist and washes it away. After the rinse, a short spin dries the wafer before the soft bake. Backside rinse may be done as part of the spin-off step(s). During the backside rinse solvent inevitably creeps onto the front side of the wafer, and may remove the resist coating on the edge of the wafer. As an alternative to backside rinse, a wafer which is left dirty on the backside by the spin coat process may be soft baked in proximity in order to protect the hotplate from contamination. This leaves front side coating intact, but also leaves the backside dirty.


==Soft baking==
==Soft baking==
After spin coating the solvent in the resist formulation must be evaporated in a baking step in order to solidify the resist. This soft bake can be carried out as a contact bake or a proximity bake. In a contact bake, the wafer is held in close contact to the hotplate surface by vacuum during the bake. In a proximity bake, the wafer is first moved into close proximity, e.g. 1mm, of the hotplate surface, then held there for the duration of the bake. The hotplate temperatures of the baking modules of Spin Track 1 and 2 are fixed at temperatures relevant to the resist used, i.e. 90°C and 110°C, respectively. After baking, the wafer is cooled for 5 seconds on the coolplate.
After spin coating, the solvent in the resist formulation must be evaporated in a baking step in order to solidify the resist. This soft bake can be carried out as a contact bake or a proximity bake. In a contact bake, the wafer is held in close contact to the hotplate surface while resting on shallow bumps only 150µm above the hotplate. In a proximity bake, the wafer is first moved into proximity, e.g. 1mm, of the hotplate surface, then held there (on the lift pins) for the duration of the bake. The hotplate temperatures of the baking modules of Spin Coater: Gamma UV are set at temperatures relevant to the resist used, typically 90-110°C. After baking, the wafer is cooled for 20 seconds on the cool plate.
 
=Quality Control (QC)=
{| border="1" cellspacing="2" cellpadding="2" colspan="3"
|bgcolor="#98FB98" |'''Quality Control (QC) for Spin Coater: Gamma UV - AZ nLOF 2020'''
|-
|
*[http://labmanager.dtu.dk/d4Show.php?id=5123&mach=359 The QC procedure for Spin Coater: Gamma UV] - '''requires login'''<br>
*[http://labmanager.dtu.dk/view_binary.php?fileId=4211 The newest QC data for Spin Coater: Gamma UV] - '''requires login'''
{| {{table}}
| align="center" |
{| border="1" cellspacing="1" cellpadding="2"  align="center" style="width:400px"
 
! QC Recipe:
! (2421) DCH 100mm nLOF 2020 2um HMDS
|-
|Substrate size
|4"
|-
| Resist volume
|3 ml
|-
|Spin-off speed
|3300 rpm
|-
|Spin-off time
|30 s
 
|-
|Soft bake temperature
|110°C, contact
|-
|Soft bake time
|60 s
|-
|}
| align="center" valign="top"|
{| border="2" cellspacing="1" cellpadding="2" align="center" style="width:400px"
!QC limits
!Spin Coater: Gamma UV - AZ nLOF 2020
|-
|Nominal film thickness
|2.0 µm
|-
|Film thickness deviation from nominal
|<5%
|-
|Film thickness non-uniformity
|<5%
|-
|}
|-
|}
Spin-off speed will be adjusted if film thickness is outside the limit.
|}
 
 
 
{| border="1" cellspacing="2" cellpadding="2" colspan="3"
|bgcolor="#98FB98" |'''Quality Control (QC) for Spin Coater: Gamma UV - AZ 5214E'''
|-
|
*[http://labmanager.dtu.dk/d4Show.php?id=5123&mach=359 The QC procedure for Spin Coater: Gamma UV] - '''requires login'''<br>
*[http://labmanager.dtu.dk/view_binary.php?fileId=4211 The newest QC data for Spin Coater: Gamma UV] - '''requires login'''
{| {{table}}
| align="center" |
{| border="1" cellspacing="1" cellpadding="2"  align="center" style="width:400px"
 
! QC Recipe:
! (3411) DCH 100mm 5214E 1.5um HMDS
|-
|Substrate size
|4"
|-
| Resist volume
|3 ml
|-
|Spin-off speed
|4500 rpm
|-
|Spin-off time
|30 s
 
|-
|Soft bake temperature
|90°C, contact
|-
|Soft bake time
|60 s
|-
|}
| align="center" valign="top"|
{| border="2" cellspacing="1" cellpadding="2" align="center" style="width:400px"
!QC limits
!Spin Coater: Gamma UV - AZ 5214E
|-
|Nominal film thickness
|1.5 µm
|-
|Film thickness deviation from nominal
|<5%
|-
|Film thickness non-uniformity
|<5%
|-
|}
|-
|}
Spin-off speed will be adjusted if film thickness is outside the limit.
|}


=Standard Processes=
=Standard Processes=
==HMDS priming==
==HMDS priming==
The standard HMDS priming process has been developed to mimic the behavior of the IMTEC Star2000 HMDS oven.
The standard HMDS priming process has been developed to mimic the behavior of the IMTEC Star2000 HMDS oven, which produces a contact angle of 81-82° on an oxidized silicon surface. The fast HMDS priming has been developed to have a process time of approximately one minute, in order to match the process time of typical coating and softbaking processes.
It produces a contact angle of 81-82° on an oxidized silicon surface. General information on HMDS priming can be found  [[Specific_Process_Knowledge/Lithography/Coaters/Spin_Coater:_Gamma_UV_processing#HMDS priming|here]].
General information on HMDS priming can be found  [[Specific_Process_Knowledge/Lithography/Coaters/Spin_Coater:_Gamma_UV_processing#HMDS priming|here]].


''Sequence names, process parameters, and test results (Sequence no. 0000-0999):''
''Sequence names, process parameters, and test results (Sequence no. 0000-0999):''
*'''(0001) HMDS Standard'''
*'''(0401) DCH 100mm HMDS Standard'''
*'''(0601) DCH 150mm HMDS Standard'''
VPO temperature: 120°C <br>
VPO temperature: 120°C <br>
Process parameters: 30s vacuum bake @ -0.67 bar, HMDS injection, 90s reaction @ ambient, 20s cooling @ 21°C.
Process parameters: 30s vacuum bake @ -0.67 bar, HMDS injection, 90s reaction @ ambient, 20s cooling @ 21°C.


Test results:
Test results:
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"  
{|border="1" cellspacing="1" cellpadding="10" style="text-align:left;"
|-
|-


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|
|
|
|
|taran
|
|average of nine measurements (three measurements on three different samples)
|average of nine measurements (three measurements on three different samples)


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|
|
|
|
|taran
|
|average of three measurements on one sample
|average of three measurements on one sample


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*''' (0002) HMDS fast'''
*''' (0402) DCH 100mm HMDS Fast'''
*''' (0602) DCH 150mm HMDS Fast'''
VPO temperature: 120°C <br>
VPO temperature: 120°C <br>
Process parameters: 30s vacuum bake @ -0.67 bar, HMDS injection, 15s reaction @ ambient, 20s cooling @ 21°C.
Process parameters: 30s vacuum bake @ -0.67 bar, HMDS injection, 15s reaction @ ambient, 20s cooling @ 21°C.


Test results:
Test results:
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"  
{|border="1" cellspacing="1" cellpadding="10" style="text-align:left;"  
|-
|-


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|
|
|
|
|taran
|
|average of nine measurements (three measurements on three different samples)
|average of nine measurements (three measurements on three different samples)


Line 136: Line 248:
|
|
|
|
|taran
|
|average of three measurements on one sample
|average of three measurements on one sample


Line 165: Line 277:
|-style="background:WhiteSmoke; color:black"
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|Silicon with native oxide
|1.513
|1.513 µm
|0.6%
|0.6%
|26/3 2015
|26/3 2015
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|1.509 µm
|0.3%
|4/11 2015
|taran
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
Line 196: Line 316:
|1.5%
|1.5%
|26/3 2015
|26/3 2015
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|2.000 µm
|0.5%
|4/11 2015
|taran
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
Line 224: Line 352:
|0.7%
|0.7%
|26/3 2015
|26/3 2015
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|4.059 µm
|0.7%
|4/11 2015
|taran
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|}
|}


==AZ nLOF 2020 coating==
==AZ nLOF 2020 coating==
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|-style="background:WhiteSmoke; color:black"
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|Silicon with native oxide
|1.559
|1.559 µm
|0.4%
|0.4%
|27/3 2015
|27/3 2015
|taran
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|1.572 µm
|0.8%
|4/11 2015
|taran
|4" wafer, with HMDS. 9 points on one wafer, exclusion zone 5mm
|}
|}




*'''(2420) DCH 100mm nLOF 2020 2um'''
*'''(2420) DCH 100mm nLOF 2020 2um'''
*'''(2421) DCH 100mm nLOF 2020 2um HMDS'''
*'''(2421) DCH 100mm nLOF 2020 2um HMDS''' see also [[Specific_Process_Knowledge/Lithography/Coaters/Spin_Coater:_Gamma_UV_processing#Quality_Control_.28QC.29|'''QC''']]
*'''(2620) DCH 150mm nLOF 2020 2um'''
*'''(2620) DCH 150mm nLOF 2020 2um'''
*'''(2621) DCH 150mm nLOF 2020 2um HMDS'''
*'''(2621) DCH 150mm nLOF 2020 2um HMDS'''
Line 292: Line 437:
|16/3 2015
|16/3 2015
|taran
|taran
|SAT results. 6" wafer, with HMDS. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 9 points on each wafer, exclusion zone 5mm.
|SAT results. 6" wafer, with HMDS. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 13 points on each wafer, exclusion zone 5mm.
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|2.064 µm
|0.8%
|4/11 2015
|taran
|4" wafer, with HMDS. 9 points on one wafer, exclusion zone 5mm
|}
|}


Line 321: Line 474:
|taran
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|4.131 µm
|0.5%
|4/11 2015
|taran
|4" wafer, with HMDS. 9 points on one wafer, exclusion zone 5mm
|}
|}


Line 330: Line 491:
''Sequence names, process parameters, and test results (Sequence no. 3000-3999):''
''Sequence names, process parameters, and test results (Sequence no. 3000-3999):''
*'''(3410) DCH 100mm 5214E 1.5um'''
*'''(3410) DCH 100mm 5214E 1.5um'''
*'''(3411) DCH 100mm 5214E 1.5um HMDS'''
*'''(3411) DCH 100mm 5214E 1.5um HMDS''' see also [[Specific_Process_Knowledge/Lithography/Coaters/Spin_Coater:_Gamma_UV_processing#Quality_Control_.28QC.29|'''QC''']]
*'''(3610) DCH 150mm 5214E 1.5um'''
*'''(3610) DCH 150mm 5214E 1.5um'''
*'''(3611) DCH 150mm 5214E 1.5um HMDS'''
*'''(3611) DCH 150mm 5214E 1.5um HMDS'''
Line 425: Line 586:
|6" wafer, no HMDS. 13 points on one wafer, exclusion zone 5mm
|6" wafer, no HMDS. 13 points on one wafer, exclusion zone 5mm
|}
|}
=Syringe processes=
Use of the syringe requires special training, and would as a starting point require batches in excess of 20 wafers.


==AZ 4562 coating (syringe)==
==AZ 4562 coating (syringe)==
Spin coating of standard thicknesses (5 - 10 µm) of AZ 4562 dispensed from syringe on Spin Coater: Gamma UV is divided into two or three steps: HMDS priming (optional), spin coating, and soft baking. The HMDS priming is equal to the ''HMDS fast'' process. Spin coating uses dynamic dispense of resist at 300 rpm, using a volume of 3 ml for 100 mm substrates, and 6 ml for 150 mm substrates, respectively. The dispense is followed by spin-off at a thickness dependent spin speed for 30 seconds with backside rinse. The wafer dried at 800 rpm for 15s before stopping. Soft baking is done at 100°C in 1 mm proximity for a thickness dependent time. The coating may be affected by the backside rinse at the very edge of the wafer, something which should be considered if the resist is used as an etch mask.
Spin coating of standard thicknesses (5 - 10 µm) of AZ 4562 dispensed from syringe on Spin Coater: Gamma UV is divided into two steps: Spin coating, and soft baking. The spin coating uses dynamic dispense of resist at 300 rpm, using a volume of 3 ml for 100 mm substrates, and 6 ml for 150 mm substrates, respectively. The dispense is followed by spin-off at a thickness dependent spin speed for 30 seconds with backside rinse. The wafer dried at 800 rpm for 15s before stopping. Soft baking is done at 100°C in 1 mm proximity for a thickness dependent time. The coating may be affected by the backside rinse at the very edge of the wafer, something which should be considered if the resist is used as an etch mask.


''Sequence names, process parameters, and test results (Sequence no. 4000-4999):''
''Sequence names, process parameters, and test results (Sequence no. 4000-4999):''
*'''(4460) DCH 100mm 4562 6.2um'''
*'''(4462) DCH 100mm 4562 6.2um'''
*'''(4461) DCH 100mm 4562 6.2um HMDS'''
*'''(4662) DCH 150mm 4562 6.2um'''
*'''(4660) DCH 150mm 4562 6.2um'''
*'''(4661) DCH 150mm 4562 6.2um HMDS'''
Spin-off: 5165 rpm. Soft bake: 100s.
Spin-off: 5165 rpm. Soft bake: 100s.


Line 452: Line 615:
|19/3 2015
|19/3 2015
|taran
|taran
|SAT results. 4" wafer, no HMDS. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 9 points on each wafer, exclusion zone 5mm.
|SAT results. 4" wafer. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 9 points on each wafer, exclusion zone 5mm.
|-
|-
|-style="background:WhiteSmoke; color:black"
|-style="background:WhiteSmoke; color:black"
Line 460: Line 623:
|19/3 2015
|19/3 2015
|taran
|taran
|SAT results. 6" wafer, no HMDS. 3 wafers measured: thickness is average of all 3; uniformity is worst case. 13 points on each wafer, exclusion zone 5mm.
|SAT results. 6" wafer. 3 wafers measured: thickness is average of all 3; uniformity is worst case. 13 points on each wafer, exclusion zone 5mm.
|}
|}




*'''(4410) DCH 100mm 4562 10um'''
*'''(4410) DCH 100mm 4562 10um'''
*'''(4411) DCH 100mm 4562 10um HMDS'''
*'''(4610) DCH 150mm 4562 10um'''
*'''(4610) DCH 150mm 4562 10um'''
*'''(4611) DCH 150mm 4562 10um HMDS'''
Spin-off: 2000 rpm. Soft bake: 300s.
Spin-off: 2000 rpm. Soft bake: 300s.


Line 486: Line 647:
|20/3 2015
|20/3 2015
|taran
|taran
|4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm.
|4" wafer. 9 points on one wafer, exclusion zone 5mm.
|}
 
 
==AZ "5206E" coating (syringe)==
 
Spin coating of AZ 5206E (AZ 5214E 1:1 by volume in PGMEA) dispensed from syringe on Spin Coater: Gamma UV is divided into three steps: HMDS priming, spin coating, and soft baking. The HMDS priming is equal to the ''HMDS fast'' process. The spin coating uses dynamic dispense of resist at 800? rpm, using a volume of 1.5 ml for 100 mm substrates. The dispense is followed by spin-off at a thickness dependent spin speed for 30 seconds. The thickness range is approximately 0.4-0.6µm. Soft baking is done at 90°C for 60s.
 
''Sequence names, process parameters, and test results (Sequence no. 4000-4999):''
*'''(4405) 100mm 5206E 0,5um HMDS'''
Spin-off: 2200 rpm, but likely to change with each new mix of resist.
 
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"
|-
|-style="background:silver; color:black"
!Substrate
!Thickness
!Uniformity (+/-)
!Spin-off speed
!Test date
!Tester initials
!Comments
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|0.49 µm
|0.9%
|2200 rpm
|23/4 2018?
|taran
|4" wafer, no HMDS. 9 points measured, exclusion zone 5mm.
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|0.54
|0.4%
|2200? rpm
|30/1 2019
|taran
|4" wafer, with HMDS. 9 points measured, exclusion zone 5mm.
|}
|}

Latest revision as of 11:16, 3 February 2023

This section, including all images and pictures, is created by DTU Nanolab staff unless otherwise stated.

Feedback to this page: click here

General Process Information

Processing using Spin Coater: Gamma UV is divided into three parts:

  • HMDS priming
  • Spin coating
  • Soft baking


Features of Spin Coater: Gamma UV

  • Cassette-to-cassette wafer handling
  • In-line HMDS priming

HMDS priming

The process of HMDS priming on Spin Coater: Gamma UV consists of five steps:

  • Dehydration
  • HMDS injection
  • Reaction
  • Purging
  • Cooling


The top and bottom heaters of the VPO module are typically set to 120°C. The wafer is baked under a low vacuum (~0.35 bar) in order to heat and dehydrate the wafer before HMDS application. The HMDS is injected into the process chamber using nitrogen as a carrier gas. 10 liters per minute of dry nitrogen is bubbled through liquid HMDS before flowing into the chamber. The injection lasts until ambient pressuer is reached in the chamber. After the reaction time, the chamber is purged using nitrogen. Finally, the wafer is cooled on the cool plate.

The contact angle after HMDS priming is a function of the priming temperature, the priming time, and the surface condition of the wafer. The condition of the substrate surface is again a function of the substrate type, the substrate history, and the effectiveness of the dehydration step. Since the vapor pressure of water at the chamber temperature is much higher than the dehydration pressure, similarly the boiling point of water at the dehydration pressure is well below the chamber temperature, the dehydration can probably be considered to be quite effective. However, for thick oxides, transport effects may cause the 30s dehydration time to be insufficient to dehydrate the surface sufficiently.

Spin coating

The process of spin coating on Spin Coater: Gamma UV consists of a selection of the following steps:

  • Acceleration to a low spin speed if dynamic dispense is used
  • Resist dispense
  • Spin-off
  • Backside rinse using PGMEA


The wafer is first centered on the spindle chuck and held in place by vacuum. If static dispense is specified in the process, the spindle remains static during the ensuing resist dispense. In the case of dynamic dispense, the spindle is accelerated to a low spin speed before the resist is dispensed. Using too high spin speed during dispense can cause surface wetting issues, while a too low spin speed causes the resist to flow onto the backside of the wafer. The resist is dispensed through the dispense arm, positioned over the center of the wafer. The resist pump administers a volume of resist which depends on the substrate size.

The spin-off cycle determines the thickness of the resist coating. The thickness is primarily a function of the spin-off speed and the spin-off time, both following an inverse power-law. The acceleration to the spin-off speed also influences the thickness, but the effect is dependent on previous steps. The spin-off is usually a simple spin at one speed, but it may be comprised of several steps at different spin speeds. After spin-off, the wafer is decelerated.

Dependent on the spin speeds used in the various steps of the spin coating, resist may creep over the edge of the wafer and onto the backside. Also, some resists tend to leave fine strings of resist protruding from the edge of the wafer, or folded onto the backside, an effect sometimes referred to as "cotton candy". This resist will contaminate the soft bake hotplate, and thus subsequent wafers with resist. In a backside rinse step, solvent administered through a nozzle to the backside of the wafer while spinning dissolves the resist and washes it away. After the rinse, a short spin dries the wafer before the soft bake. Backside rinse may be done as part of the spin-off step(s). During the backside rinse solvent inevitably creeps onto the front side of the wafer, and may remove the resist coating on the edge of the wafer. As an alternative to backside rinse, a wafer which is left dirty on the backside by the spin coat process may be soft baked in proximity in order to protect the hotplate from contamination. This leaves front side coating intact, but also leaves the backside dirty.

Soft baking

After spin coating, the solvent in the resist formulation must be evaporated in a baking step in order to solidify the resist. This soft bake can be carried out as a contact bake or a proximity bake. In a contact bake, the wafer is held in close contact to the hotplate surface while resting on shallow bumps only 150µm above the hotplate. In a proximity bake, the wafer is first moved into proximity, e.g. 1mm, of the hotplate surface, then held there (on the lift pins) for the duration of the bake. The hotplate temperatures of the baking modules of Spin Coater: Gamma UV are set at temperatures relevant to the resist used, typically 90-110°C. After baking, the wafer is cooled for 20 seconds on the cool plate.

Quality Control (QC)

Quality Control (QC) for Spin Coater: Gamma UV - AZ nLOF 2020
QC Recipe: (2421) DCH 100mm nLOF 2020 2um HMDS
Substrate size 4"
Resist volume 3 ml
Spin-off speed 3300 rpm
Spin-off time 30 s
Soft bake temperature 110°C, contact
Soft bake time 60 s
QC limits Spin Coater: Gamma UV - AZ nLOF 2020
Nominal film thickness 2.0 µm
Film thickness deviation from nominal <5%
Film thickness non-uniformity <5%

Spin-off speed will be adjusted if film thickness is outside the limit.


Quality Control (QC) for Spin Coater: Gamma UV - AZ 5214E
QC Recipe: (3411) DCH 100mm 5214E 1.5um HMDS
Substrate size 4"
Resist volume 3 ml
Spin-off speed 4500 rpm
Spin-off time 30 s
Soft bake temperature 90°C, contact
Soft bake time 60 s
QC limits Spin Coater: Gamma UV - AZ 5214E
Nominal film thickness 1.5 µm
Film thickness deviation from nominal <5%
Film thickness non-uniformity <5%

Spin-off speed will be adjusted if film thickness is outside the limit.

Standard Processes

HMDS priming

The standard HMDS priming process has been developed to mimic the behavior of the IMTEC Star2000 HMDS oven, which produces a contact angle of 81-82° on an oxidized silicon surface. The fast HMDS priming has been developed to have a process time of approximately one minute, in order to match the process time of typical coating and softbaking processes. General information on HMDS priming can be found here.

Sequence names, process parameters, and test results (Sequence no. 0000-0999):

  • (0401) DCH 100mm HMDS Standard
  • (0601) DCH 150mm HMDS Standard

VPO temperature: 120°C
Process parameters: 30s vacuum bake @ -0.67 bar, HMDS injection, 90s reaction @ ambient, 20s cooling @ 21°C.

Test results:

Substrate Contact angle Test date Tester initials Comments
Si with native oxide 78±1° 28/5 2015 taran average of three measurements on three samples from three different days
110 nm oxide average of nine measurements (three measurements on three different samples)
Borofloat (glass) average of three measurements on one sample


  • (0402) DCH 100mm HMDS Fast
  • (0602) DCH 150mm HMDS Fast

VPO temperature: 120°C
Process parameters: 30s vacuum bake @ -0.67 bar, HMDS injection, 15s reaction @ ambient, 20s cooling @ 21°C.

Test results:

Substrate Contact angle Test date Tester initials Comments
Si with native oxide 70±1° 28/5 2015 taran average of three measurements on three samples from three different days
110 nm oxide average of nine measurements (three measurements on three different samples)
Borofloat (glass) average of three measurements on one sample

AZ MiR 701 (29cps) coating

Spin coating of standard thicknesses (1.3 - 2.5 µm) of AZ MiR 701 (29cps) on Spin Coater: Gamma UV is divided into two or three steps: HMDS priming (optional), spin coating, and soft baking. The HMDS priming is equal to the HMDS fast process. Spin coating uses dynamic dispense of resist at 800 rpm, using a volume of 3 ml for 100 mm substrates, and 5 ml for 150 mm substrates, respectively. The dispense is followed by spin-off at a thickness dependent spin speed for 30 seconds. The wafer is decelerated at 2000 rpm/s before stopping. Soft baking is done at 90°C for 60s. As MiR 701 has a tendency to produce "cotton candy" on the edges, soft baking is performed in 1 mm proximity.

In order to achieve thicker coatings of AZ MiR 701 (29cps) while minimizing edge bead problems, a method of waiting before spin-off is used on Spin Coater: Gamma UV. The spin coating process consists of three steps: dispense, waiting, and spin-off. The first step is dynamic dispense of resist at 800 rpm, using a volume of 3 ml for 100 mm substrates, and 5 ml for 150 mm substrates, respectively. In the waiting step the resist is "dried" at low spin speed without exhaust (in practice the exhaust is opened briefly every 15s in order to avoid triggering the exhaust alarm). The final spin-off step is short, but at relatively high spin speed, with backside rinse the first half of the time. Soft baking is done at 90°C for 90s. Contact baking is used since the backside is clean. The coating may be affected by the backside rinse at the very edge of the wafer, something which should be considered if the resist is used as an etch mask.

Sequence names, process parameters, and test results (Sequence no. 1000-1999):

  • (1410) DCH 100mm MiR 701 1.5um
  • (1411) DCH 100mm MiR 701 1.5um HMDS
  • (1610) DCH 150mm MiR 701 1.5um
  • (1611) DCH 150mm MiR 701 1.5um HMDS

Spin-off: 4600 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 1.513 µm 0.6% 26/3 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
Silicon with native oxide 1.509 µm 0.3% 4/11 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm


  • (1420) DCH 100mm MiR 701 2um
  • (1421) DCH 100mm MiR 701 2um HMDS
  • (1620) DCH 150mm MiR 701 2um
  • (1621) DCH 150mm MiR 701 2um HMDS

Spin-off: 2600 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 2.019 µm 1.5% 26/3 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
Silicon with native oxide 2.000 µm 0.5% 4/11 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm


  • (1440) DCH 100mm MiR 701 4um
  • (1441) DCH 100mm MiR 701 4um HMDS
  • (1640) DCH 150mm MiR 701 4um
  • (1641) DCH 150mm MiR 701 4um HMDS

Waiting: 75s @ 600 rpm. Spin-off: 10s @ 3000 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 3.992 µm 0.7% 26/3 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
Silicon with native oxide 4.059 µm 0.7% 4/11 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm


AZ nLOF 2020 coating

Spin coating of standard thicknesses (1.5 - 3 µm) of AZ nLOF 2020 on Spin Coater: Gamma UV is divided into two or three steps: HMDS priming (optional), spin coating, and soft baking. The HMDS priming is equal to the HMDS fast process. Spin coating uses dynamic dispense of resist at 800 rpm, using a volume of 3 ml for 100 mm substrates, and 5 ml for 150 mm substrates, respectively. The dispense is followed by spin-off at a thickness dependent spin speed for 30 seconds. The wafer is decelerated at 2000 rpm/s before stopping. Soft baking is done at 110°C for 60s.

In order to achieve thicker coatings of AZ nLOF 2020 while minimizing edge bead problems, a method of waiting before spin-off is used on Spin Coater: Gamma UV. The spin coating process consists of three steps: dispense, waiting, and spin-off. The first step is dynamic dispense of resist at 800 rpm, using a volume of 3 ml for 100 mm substrates, and 5 ml for 150 mm substrates, respectively. In the waiting step the resist is "dried" at low spin speed without exhaust (in practice the exhaust is opened briefly every 15s in order to avoid triggering the exhaust alarm). The final spin-off step is short, but at relatively high spin speed, with backside rinse the first half of the time. Soft baking is done at 110°C for 120s. Contact baking is used since the backside has been cleaned. The coating may be affected by the backside rinse at the very edge of the wafer, something which should be considered if the resist is used as an etch mask.

Sequence names, process parameters, and test results (Sequence no. 2000-2999):

  • (2410) DCH 100mm nLOF 2020 1.5um
  • (2411) DCH 100mm nLOF 2020 1.5um HMDS
  • (2610) DCH 150mm nLOF 2020 1.5um
  • (2611) DCH 150mm nLOF 2020 1.5um HMDS

Spin-off: 6000 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 1.559 µm 0.4% 27/3 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
Silicon with native oxide 1.572 µm 0.8% 4/11 2015 taran 4" wafer, with HMDS. 9 points on one wafer, exclusion zone 5mm


  • (2420) DCH 100mm nLOF 2020 2um
  • (2421) DCH 100mm nLOF 2020 2um HMDS see also QC
  • (2620) DCH 150mm nLOF 2020 2um
  • (2621) DCH 150mm nLOF 2020 2um HMDS

Spin-off: 3300 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 2.018 µm 0.5% 16/3 2015 taran SAT results. 4" wafer, with HMDS. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 9 points on each wafer, exclusion zone 5mm.
Silicon with native oxide 2.032 µm 0.8% 16/3 2015 taran SAT results. 6" wafer, with HMDS. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 13 points on each wafer, exclusion zone 5mm.
Silicon with native oxide 2.064 µm 0.8% 4/11 2015 taran 4" wafer, with HMDS. 9 points on one wafer, exclusion zone 5mm


  • (2440) DCH 100mm nLOF 2020 4um
  • (2441) DCH 100mm nLOF 2020 4um HMDS
  • (2640) DCH 150mm nLOF 2020 4um
  • (2641) DCH 150mm nLOF 2020 4um HMDS

Waiting: 45s @ 600 rpm. Spin-off: 10s @ 3500 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 4.076 µm 0.7% 27/3 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
Silicon with native oxide 4.131 µm 0.5% 4/11 2015 taran 4" wafer, with HMDS. 9 points on one wafer, exclusion zone 5mm

AZ 5214E coating

Spin coating of standard thicknesses (1.5 - 3 µm) of AZ nLOF 2020 on Spin Coater: Gamma UV is divided into two or three steps: HMDS priming (optional), spin coating, and soft baking. The HMDS priming is equal to the HMDS fast process. Spin coating uses dynamic dispense of resist at 800 rpm, using a volume of 3 ml for 100 mm substrates, and 5 ml for 150 mm substrates, respectively. The dispense is followed by spin-off at a thickness dependent spin speed for 30 seconds. The wafer is decelerated at 2000 rpm/s before stopping. Soft baking is done at 90°C for 60s.

In order to achieve thicker coatings of AZ 5214E while minimizing edge bead problems, a method of waiting before spin-off is used on Spin Coater: Gamma UV. The spin coating process consists of three steps: dispense, waiting, and spin-off. The first step is dynamic dispense of resist at 800 rpm, using a volume of 3 ml for 100 mm substrates, and 5 ml for 150 mm substrates, respectively. In the waiting step the resist is "dried" at low spin speed without exhaust (in practice the exhaust is opened briefly every 15s in order to avoid triggering the exhaust alarm). The final spin-off step is short, but at relatively high spin speed, with backside rinse the first half of the time. Soft baking is done at 100°C for 90s in 1mm proximity. The coating may be affected by the backside rinse at the very edge of the wafer, something which should be considered if the resist is used as an etch mask.

Sequence names, process parameters, and test results (Sequence no. 3000-3999):

  • (3410) DCH 100mm 5214E 1.5um
  • (3411) DCH 100mm 5214E 1.5um HMDS see also QC
  • (3610) DCH 150mm 5214E 1.5um
  • (3611) DCH 150mm 5214E 1.5um HMDS

Spin-off: 4500 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 1.500 µm 0.6% 20/3 2015 taran SAT results. 4" wafer, with HMDS. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 9 points on each wafer, exclusion zone 5mm.
Silicon with native oxide 1.507 µm 1.0% 20/3 2015 taran SAT results. 6" wafer, with HMDS. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 13 points on each wafer, exclusion zone 5mm.


  • (3420) DCH 100mm 5214E 2.2um
  • (3421) DCH 100mm 5214E 2.2um HMDS
  • (3620) DCH 150mm 5214E 2.2um
  • (3621) DCH 150mm 5214E 2.2um HMDS

Spin-off: 2100 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 2.201 0.5% 20/3 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm


  • (3440) DCH 100mm 5214E 4.2um
  • (3441) DCH 100mm 5214E 4.2um HMDS
  • (3640) DCH 150mm 5214E 4.2um
  • (3641) DCH 150mm 5214E 4.2um HMDS

Waiting: 60s @ 600 rpm. Spin-off: 10s @ 3500 rpm.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 4.171 µm 0.7% 20/3 2015 taran 4" wafer, no HMDS. 9 points on one wafer, exclusion zone 5mm
Silicon with native oxide 4.194 µm 0.5% 20/3 2015 taran 6" wafer, no HMDS. 13 points on one wafer, exclusion zone 5mm

Syringe processes

Use of the syringe requires special training, and would as a starting point require batches in excess of 20 wafers.

AZ 4562 coating (syringe)

Spin coating of standard thicknesses (5 - 10 µm) of AZ 4562 dispensed from syringe on Spin Coater: Gamma UV is divided into two steps: Spin coating, and soft baking. The spin coating uses dynamic dispense of resist at 300 rpm, using a volume of 3 ml for 100 mm substrates, and 6 ml for 150 mm substrates, respectively. The dispense is followed by spin-off at a thickness dependent spin speed for 30 seconds with backside rinse. The wafer dried at 800 rpm for 15s before stopping. Soft baking is done at 100°C in 1 mm proximity for a thickness dependent time. The coating may be affected by the backside rinse at the very edge of the wafer, something which should be considered if the resist is used as an etch mask.

Sequence names, process parameters, and test results (Sequence no. 4000-4999):

  • (4462) DCH 100mm 4562 6.2um
  • (4662) DCH 150mm 4562 6.2um

Spin-off: 5165 rpm. Soft bake: 100s.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 6.209 µm 1.0% 19/3 2015 taran SAT results. 4" wafer. 5 wafers measured: thickness is average of all 5; uniformity is worst case. 9 points on each wafer, exclusion zone 5mm.
Silicon with native oxide 6.224 µm 0.7% 19/3 2015 taran SAT results. 6" wafer. 3 wafers measured: thickness is average of all 3; uniformity is worst case. 13 points on each wafer, exclusion zone 5mm.


  • (4410) DCH 100mm 4562 10um
  • (4610) DCH 150mm 4562 10um

Spin-off: 2000 rpm. Soft bake: 300s.

Substrate Thickness Uniformity (+/-) Test date Tester initials Comments
Silicon with native oxide 9.982 µm 0.4% 20/3 2015 taran 4" wafer. 9 points on one wafer, exclusion zone 5mm.


AZ "5206E" coating (syringe)

Spin coating of AZ 5206E (AZ 5214E 1:1 by volume in PGMEA) dispensed from syringe on Spin Coater: Gamma UV is divided into three steps: HMDS priming, spin coating, and soft baking. The HMDS priming is equal to the HMDS fast process. The spin coating uses dynamic dispense of resist at 800? rpm, using a volume of 1.5 ml for 100 mm substrates. The dispense is followed by spin-off at a thickness dependent spin speed for 30 seconds. The thickness range is approximately 0.4-0.6µm. Soft baking is done at 90°C for 60s.

Sequence names, process parameters, and test results (Sequence no. 4000-4999):

  • (4405) 100mm 5206E 0,5um HMDS

Spin-off: 2200 rpm, but likely to change with each new mix of resist.

Substrate Thickness Uniformity (+/-) Spin-off speed Test date Tester initials Comments
Silicon with native oxide 0.49 µm 0.9% 2200 rpm 23/4 2018? taran 4" wafer, no HMDS. 9 points measured, exclusion zone 5mm.
Silicon with native oxide 0.54 0.4% 2200? rpm 30/1 2019 taran 4" wafer, with HMDS. 9 points measured, exclusion zone 5mm.
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