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=<span style="background:#FF2800">THIS PAGE IS UNDER CONSTRUCTION</span>[[image:Under_construction.png|200px]]=
{{:Specific Process Knowledge/Lithography/authors_generic}}
 
'''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:_RCD8_processing click here]'''
 
[[Category: Equipment|Lithography]]
[[Category: Lithography]]
 
__TOC__
 


=Spin coating=
=Spin coating=
The process of spin coating on Spin Coater: RCD8 consists of a selection of the following steps:
Spin coating on Spin Coater: RCD8 consists of a selection of the following steps:
*Acceleration to a low spin speed if dynamic dispense is used
#Resist dispense
*Resist dispense
#(Recipe start)
*Closing the Gyrset
#Optional: Closing the Gyrset (if used)
*Resist spreading at low spin speed
#Optional: Resist spreading at low spin speed
*Spin-off
#Spin-off
*Deceleration
#Deceleration
*Opening Gyrset
#Opening Gyrset (if used)
 
 
The wafer is first centered on the chuck and held in place by vacuum (or pins in the case of the non-vacuum chuck). After the resist has been dispensed, the recipe is started. A short spin at low spin speed may be used as the first step of the recipe, 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.
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.
 
=Dispense=
 
Resist dispense on the Spin Coater: RCD8 can only be done manually, as the motorized media arm was decommissioned in 2024. Manual dispense is done by administering the resist directly onto the substrate, after it has been loaded into the machine but before the recipe has been started. In most cases, it is done by pushing the resist out of a prefilled syringe (dispense cartridge). Thin resists can be dispensed by pouring the resist directly from a bottle, but that is more difficult to control.
 
The volume dispensed from a syringe may be estimated by measuring the distance the resist level is displaced during a dispense, and calculating the corresponding volume using the diameter of the syringe (23 mm). A displacement of 10 mm corresponds to a dispensed volume of 4 ml. This calculation can also be used to mark the syringe with appropriately spaced guide lines in order to dispense a specific volume. 4-5 ml is an appropriate volume for a 100 mm wafer.
 
==Tips and tricks for dispensing thick resist==
High viscosity resists, such as the SU-8 formulations for coating thicknesses 50µm and above, are difficult to dispense. To have any kind of control, they require use of a dispense syringe.


The wafer is first centered on the chuck and held in place by vacuum (or pins in the case of the non-vacuum chuck). If static dispense is used, 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 may be dispensed manually, or automatically using the syringe dispense system on the media arm. 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.  
'''Filling the syringe:'''<br>
Syringes should be filled the day before spin coating, especially for thick resists like SU-8 3035 or XFT 75. They should be stored vertical in order to allow bubbles to settle at the top.  


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.
A syringe consists of an end cap, the syringe barrel, and a piston that seals off the syringe after filling. To fill a syringe, bring all the necessary parts to a fume hood, along with the resist bottle. It is recommended to clean all parts with a nitrogen gun (these parts are standard labware and therefore not supplied particle-free). Put the end cap on the syringe barrel and open the resist bottle. Hold the syringe at a slight angle and slowly start pouring the resist from the bottle. Start gently and be patient; the flow of resist can quickly become too fast and too wide for the syringe. Allow the resist to flow down along the inner wall of the syringe to minimize bubble formation, taking care to avoid the top few cm of the syringe. You'll need some free space at the top for the piston; so, please stop pouring the resist before it's too late, as the viscous resist will continue to flow once you have lowered the bottle. If the resist drips on the outside of the bottle, wipe it off, but avoid wiping the opening of the bottle (due to risk of contaminating the remaining resist). When you have put down the resist bottle, insert the piston and push it all the way down to the surface of the resist in the syringe. Wipe any resist from the end of the syringe. Finally, label your syringe and store it in the chemical cabinet (in E-4).


The coated thickness, t, as a function of the spin-off speed, w, follows an inverse power-law t=k*w^-a. The constant, k, is a function of the resist viscosity and solid content, and the spin-off time. The exponent, a, is dependent on solvent evaporation, and is usually ~½. This means that from the thickness t1 achieved at spin speed w1, one can estimate the thickness t2 at spin speed w2 using the relation: <br> t1*w1<sup>2</sup> = t2*w2<sup>2</sup> => t2 = t1 * w1<sup>2</sup>/w2<sup>2</sup>. <br> For SU-8, however, a is observed to be ~1 (probably due to the low solvent content and/or the formation of skin). In this case, the relation simply becomes: <br> t1*w1 = t2*w2 => t2 = t1 * w1/w2. <br>
'''Dispensing from the syringe:'''<br>
Start by removing the end cap from the syringe. For the first dispense, remove any air in the tip of the syringe by dispensing the first drop somewhere outside the substrate. Start the dispense in the center of the wafer, keeping the tip of the syringe as close to the substrate as possible (so the dispensed resist forms a continuous puddle, rather than strings that bunch up and trap air). Make sure the dispensed resist puddle is in the center of the substrate; otherwise, some of the substrate may not be covered during spinning, even though a lot of resist was dispensed. During dispensing, the position of the puddle can be controlled by moving the syringe tip while continuing the dispensing process. Towards the end of the dispense, move the tip to the edge of the puddle. Stop the dispense, but keep the tip at the last spot to allow the last resist to finish flowing. Now, lift the tip a couple of cm up, then down again and up again, in order to break the thin string of resist that forms between the tip and the puddle.  


=Automatic dispense=
'''Bubbles in the resist film after coating:'''<br>
Bubbles in the resist after coating can successfully be popped (using e.g. an Eppendorf pipette tip), either while still on the chuck or after moving to the hotplate. Sometimes bubbles appear in the film during the first stage of softbaking. These can also be popped.
<!--
Text below was in the original section "Automatic dispense" TARAN 27-08-2025


Automatic dispense on the Spin Coater: RCD8 is done using a Nordson EFD Performus VII pressurised cartridge dispense system. The syringe containing the resist is mounted on the media arm, and the resist is dispensed using a nitrogen pressure supplied by the control box. The dispense rate is controlled by the nitrogen pressure, while the dispense time, and thus the volume, is set in the recipe. The dispensed volume may be estimated by measuring the distance the syringe cap is displaced during a dispense, and calculating the corresponding volume using the diameter of the syringe (23 mm).
Automatic dispense on the Spin Coater: RCD8 is done using a Nordson EFD Performus VII pressurised cartridge dispense system. The syringe containing the resist is mounted on the media arm, and the resist is dispensed using a nitrogen pressure supplied by the control box. The dispense rate is controlled by the nitrogen pressure, while the dispense time, and thus the volume, is set in the recipe. The dispensed volume may be estimated by measuring the distance the resist level is displaced during a dispense, and calculating the corresponding volume using the diameter of the syringe (23 mm). A displacement of 10 mm corresponds to a dispensed volume of 4 mL.


Observed dispense rates (uncertainty from measurements ~0.1 ml/s):
Observed dispense rates (uncertainty from measurements ~0.1 ml/s):
Line 26: Line 54:
**0.5 ml/s @ 2.0 bar
**0.5 ml/s @ 2.0 bar
**0.7 ml/s @ 3.0 bar
**0.7 ml/s @ 3.0 bar
*'''SU-8 2035:'''
**0.5 ml/s @ 1.0 bar
*'''SU-8 2010:'''
**1.1 ml/s @ 0.1 bar
*'''KMPR 1025:'''
**0.4 ml/s @ 0.5 bar
**0.7 ml/s @ 1.0 bar
*'''AZ 5214E:'''
*'''AZ 5214E:'''
**1.2 ml/s @ 0.1 bar
**1.2 ml/s @ 0.1 bar
**2.4 ml/s @ 0.18 bar
**2.4 ml/s @ 0.18 bar


=Standard recipes=
==Edge bead removal==
==General==
The automatic dispense system may also be used to administer solvent at the edge of the wafer after spin coating in order to remove the edge bead. Edge bead removal, or EBR, is usually done using PGMEA. Due to the low viscosity of the solvent, and the relatively high pressure of the EFD control box, it is necessary to use at tip at the end of the syringe. The flow rate of the solvent is a function of the pressure and the size of the tip orifice. While the dispense rate scales roughly linearly with the pressure, it is an exponential function of the tip orifice.
*1 DCH Centering test
 
*1 DCH Chuck cleaning
Observed dispense rates of PGMEA (uncertainty from measurements ~0.1 ml/s) for different tip sizes:
*1 DCH Gyrset cleaning
*'''Red (0.010"):'''
==SU-8==
**0.2 ml/s @ 0.1 bar
*1 DCH SU8 2075 Adisp 75um
**0.25 ml/s @ 0.2 bar
*1 DCH SU8 2075 Mdisp 75um
*'''Purple (0.020"):'''
**0.3 ml/s @ 0.1 bar
**0.65 ml/s @ 0.2 bar
*'''Pink (0.024"):'''
**0.5? ml/s @ 0.1 bar (not verified)
*'''Grey (0.047"):'''
**~2.5 ml/s @ 0.1 bar
-->
 
=Recipes=
Auxiliary recipes, and template recipes. For each case a list of the steps/parameters in the respective recipe.
 
Process recipes developed by Nanolab are listed under Process results.
 
==Auxiliary recipes==
*'''1 DCH Centering test'''
5s @ 100rpm; 5s @ 250rpm; 5s @ 500rpm.
*'''1 DCH Chuck cleaning'''
10s @ 100rpm; 1s @ 0rpm; 10s @ -30rpm; 20s @ 1500rpm.
*'''1 DCH Gyrset cleaning'''
Gyrset down; 10s @ 100rpm; 1s @ 0rpm; 10s @ -30rpm; 20s @ 1500rpm; Gyrset up.
<!--
*'''1 DCH predispense'''
0.2s dispense at cup (arm position 0mm).
-->
 
==Manual dispense templates==
*'''1 TMPLT man disp'''
Spin-off; deceleration.
*'''1 TMPLT man disp spread'''
Spread step; spin-off; deceleration.
*'''1 TMPLT man disp Gyrset'''
Gyrset down; spin-off; deceleration; Gyrset up.
*'''1 TMPLT man disp Gyrset sprd'''
Gyrset down; spread step; spin-off; deceleration; Gyrset up.
<!--
==Automatic dispense templates==
*'''1 TMPLT aut disp SU8'''
Dispense; SU-8 string breaking; spread step; spin-off; deceleration.
*'''1 TMPLT aut disp SU8 Gyrset'''
Dispense; SU-8 string breaking; Gyrset down; spread step; spin-off; deceleration; Gyrset up.
*'''1 TMPLT aut disp'''
Dispense; spin-off; deceleration.
*'''1 TMPLT aut disp spread'''
Dispense; spread step; spin-off; deceleration.
*'''1 TMPLT aut disp Gyrset'''
Dispense; Gyrset down; spin-off; deceleration; Gyrset up.
*'''1 TMPLT aut disp Gyrset sprd'''
Dispense; Gyrset down; spread step; spin-off; deceleration; Gyrset up.
-->
 
=Processing results=
 
==SU-8 2075==
[[Image:RCD8 SU-8 2075.jpg|300x300px|thumb|right|Spin curve for SU-8 2075]]
[[Image:RCD8 SU-8 2075 Gyrset.jpg|300x300px|thumb|right|Spin curve for SU-8 2075 using Gyrset]]
Spin coating of SU-8 2075 on Spin Coater: RCD8 using automatic dispense consists of three process steps: static dispense, spread, and spin-off. In the static dispense step the media arm is moved to the center of the wafer, and resist is dispensed for 7s, yielding a volume of 3.5ml at 2.0 bar. After the dispense, the media arm is moved up and down in a series of steps designed to break the string of resist between the syringe and the wafer. In the spread step the wafer is accelerated to 700rpm at 50rpm/s, and spun for 25s. In the spin-off step the wafer is accelerated at 500rpm/s to the spin-off speed, spun for 30s, then decelerated at 1000rpm/s.
<br>In the Gyrset version, the Gyrset is closed after the dispense step, and opened after the spin-off step.
 
''Recipe names, process parameters, and test results:''
*'''1 DCH SU8 aut disp 100um'''
Spin-off: 30 s at 2100 rpm.
 
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"
|-
|-style="background:silver; color:black"
!Substrate
!Thickness
!Uniformity (+/-)
!Test date
!Tester initials
!Comments
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|100 µm
|3.5%
|14/4 2015
|taran
|5 points on one wafer, exclusion zone 15mm
|}
 
 
*'''1 DCH SU8 aut dsp Grst 100um'''
Spin-off: 30 s at 2000 rpm.
 
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"
|-
|-style="background:silver; color:black"
!Substrate
!Thickness
!Uniformity (+/-)
!Test date
!Tester initials
!Comments
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|99 µm
|3.0%
|15/4 2013
|taran
|5 points on one wafer, exclusion zone 15mm
|}
 
<br clear="all" />
 
==AZ 4562==
[[Image:RCD8 AZ 4562.jpg|300x300px|thumb|right|Spin curve for AZ 4562]]
Spin coating of AZ 4562 on Spin Coater: RCD8 using manual dispense is a very simple process. The wafer is accelerated at 1000rpm/s to the spin-off speed, spun for 30s, then decelerated at 1000rpm/s.
 
''Recipe names, process parameters, and test results:''
*'''1 DCH 4562 man disp 10um'''
Spin-off: 30 s at 2000 rpm.
 
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"
|-
|-style="background:silver; color:black"
!Substrate
!Thickness
!Uniformity (+/-)
!Test date
!Tester initials
!Comments
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|9.92 µm
|2.9%
|29/4 2015
|taran
|9 points on one wafer, exclusion zone 5mm <br> Non-vacuum chuck
|}
 
<br clear="all" />
 
==AZ 5214E==
==AZ 5214E==
*1 DCH 5214E Mdisp 1_5um
[[Image:RCD8 AZ 5214E.jpg|300x300px|thumb|right|Spin curve for AZ 5214E]]
*1 DCH 5214E Mdisp 2_2um
Spin coating of AZ 5214E on Spin Coater: RCD8 using manual dispense is a very simple process. The wafer is accelerated at 1000rpm/s to the spin-off speed, spun for 30s, then decelerated at 1000rpm/s.
*1 DCH 5214E Adisp 1_5um
 
*1 DCH 5214E Adisp 2_2um
''Recipe names, process parameters, and test results:''
 
*'''1 DCH 5214E man disp 2.2um'''
Spin-off: 30 s at 2100 rpm.
 
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"
|-
|-style="background:silver; color:black"
!Substrate
!Thickness
!Uniformity (+/-)
!Test date
!Tester initials
!Comments
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|2.19 µm
|0.4%
|22/4 2013
|taran
|9 points on one wafer, exclusion zone 5mm
|}
 
<br clear="all" />
 
==AZ MiR 701==
[[Image:RCD8 AZ MiR 701.jpg|300x300px|thumb|right|Spin curve for AZ MiR 701 (29cps)]]
Spin coating of AZ MiR 701 (29cps) on Spin Coater: RCD8 using manual dispense is a very simple process. The wafer is accelerated at 1000rpm/s to the spin-off speed, spun for 30s, then decelerated at 1000rpm/s.
 
''Recipe names, process parameters, and test results:''
*'''1 DCH MiR 701 man disp 2um''' <sup>1)</sup>
Spin-off: 30 s at 2350 rpm.
 
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"
|-
|-style="background:silver; color:black"
!Substrate
!Thickness
!Uniformity (+/-)
!Test date
!Tester initials
!Comments
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|2.00 µm
|1.8%
|29/4 2015
|taran
|9 points on one wafer, exclusion zone 5mm <br> Non-vacuum chuck
|}
 
<sup>1)</sup> Not implemented yet.
<br clear="all" />
 
==AZ nLOF 2020==
[[Image:RCD8 AZ nLOF 2020.jpg|300x300px|thumb|right|Spin curve for AZ nLOF 2020]]
Spin coating of AZ nLOF 2020 on Spin Coater: RCD8 using manual dispense is a very simple process. The wafer is accelerated at 1000rpm/s to the spin-off speed, spun for 30s, then decelerated at 1000rpm/s.
 
''Recipe names, process parameters, and test results:''
*'''1 DCH nLOF 2020 man disp 2.3um''' <sup>1)</sup>
Spin-off: 30 s at 2500 rpm.
 
{|border="1" cellspacing="0" cellpadding="3" style="text-align:left;"
|-
|-style="background:silver; color:black"
!Substrate
!Thickness
!Uniformity (+/-)
!Test date
!Tester initials
!Comments
|-
|-style="background:WhiteSmoke; color:black"
|Silicon with native oxide
|2.30 µm
|1.7%
|29/4-2015
|taran
|9 points on one wafer, exclusion zone 5mm <br> Non-vacuum chuck
|}


=Template recipes=
<sup>1)</sup> Not implemented yet.
==Manual dispense==
<br clear="all" />
*1 TEMPLATE man disp
*1 TEMPLATE man disp Gyrset
*1 TEMPLATE man disp spread
*1 TEMPLATE man disp spread Gyrset
==Automatic dispense==
*1 TEMPLATE aut SU8 disp
*1 TEMPLATE aut SU8 disp Gyrset
*1 TEMPLATE aut dyn disp
*1 TEMPLATE aut dyn disp Gyrset
*1 TEMPLATE aut stat disp
*1 TEMPLATE aut stat disp Gyrset
*1 TEMPLATE aut stat disp spread
*1 TEMPLATE aut stat disp spread Gyrset
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