Difference between revisions of "Lift-Off with DUV Imaging + PMGI Underlayer"

From UCSB Nanofab Wiki
Jump to navigation Jump to search
(initial process)
 
m
Line 1: Line 1:
−
This process is intended for Deep-UV Exposure on the ASML DUV Stepper. PMGI is used as the underlayer. This process uses PMGI SF-5, which spins to about 130nm (maximum metal thickness ≈ 130nm/3 = 45nm) and undercuts laterally about 130-140nm (minimum gap between metals = (2 x 140nm) + 30nm ≈ 350nm).
 +
This process is intended for Deep-UV Exposure on the ASML DUV Stepper. PMGI is used as the underlayer, which is exposed at the same time as the imaging resist.
   
  +
This process uses PMGI SF-5 @ 4krpm, which spins to about 130nm (maximum metal thickness = 130nm/3 ≈ 45nm) and undercuts laterally about 130-140nm (minimum gap between metals = (2 x 140nm) + 30nm ≈ 350nm).
⚫
== Tips ==
  
  +
  ⚫
==Tips==
 
Please see our [[https://www.nanotech.ucsb.edu/wiki/index.php/Lithography_Recipes#Lift-Off_Techniques Bi-Layer Lift-Off Tutorial]] to understand the limitations and requirements for good lift-off.
  
Please see our [[https://www.nanotech.ucsb.edu/wiki/index.php/Lithography_Recipes#Lift-Off_Techniques Bi-Layer Lift-Off Tutorial]] to understand the limitations and requirements for good lift-off.
   
−
* Remember that gaps in between adjacent metal traces can lift-off during the develop!
 +
*Remember that gaps in between adjacent metal traces can lift-off during the develop!
−  
⚫
* Need underlayer thickness 2x to 3x the desired metal thickness.
  
−  
⚫
* The underlayer will develop laterally from both sides which can lift-off the imaging resist, so:
  
−  
⚫
** Minimum gap between adjacent metals should then be: less than 0.5 * underlayer thickness.
 
−  
⚫
* Want at least 30-50nm of underlayer left so the PR doesn't fall over/collapse.
  
−  
⚫
* Also make sure to use a very vertical evaporation - EBeam4 or EBeam1. EBeam3 is not vertical.
  
−  
−  
⚫
== Suggested process for Liftoff ==
  
−  
⚫
De-H2O Bake (eg. 220°C, 1m+). Optionally Oxygen ash instead.
  
−  
⚫
HMDS soak 10s+
  
−  
⚫
Spin PMGI SF-5 @ 4krpm (rcp 7)
  
−  
⚫
PMGI-Bake: 220°C, 3min (lift-pins Brewer hotplate). Recipe "00 220deg, 3min Vac". Enable Vacuum with overhead valve, only for wafer landing and then turn off.
  
−  
⚫
Spin UV-6-0.8 @ rcp 6 (3.5krpm)
  
−  
⚫
--> POLOS underside clean: 2000rpm, ACE/ISO/N2
  
−  
⚫
Pre-Bake = 135°C, 1min (builtin hotplate)
  
−  
⚫
(check underside for particulates)
  
−  
⚫
ASML Exposure
  
−  
⚫
-- Default: Exp = 37.5mJ // foc = –0.10
  
−  
⚫
(Try this exposure dose - might need to do a FocArray (smaller Image Distribution eg. 5x5) to find proper exposure.
 
   
  ⚫
*Need underlayer thickness 2x to 3x the desired metal thickness.
⚫
PEB = 135°C, 1.5min (built-in hotplate)
  
   
  ⚫
*The underlayer will develop laterally from both sides which can lift-off the imaging resist, so:
⚫
Dev (300MiF) = 50sec (CRITICAL time)
  
  ⚫
**Minimum gap between adjacent metals should then be: less than 0.5 * underlayer thickness
  ⚫
**Want at least 30-50nm of underlayer width left to support the imaging resist, so the PR doesn't fall over/collapse.
   
  ⚫
*Make sure to use a vertical evaporation - EBeam4 or EBeam1. EBeam3 is not vertical.
⚫
--> with cassette & H2O dish prepared
  
   
⚫
--> not stirring, instead very slow/gentle lift/drop at various angles or gentle swish
  
   
  ⚫
==Suggested Process for Liftoff==
⚫
DI rinse : very Gently! Dunk into prepared DI dish, and dump/fill gently 2x. Don’t allow direct hard water to hit PR surface.
 
   
  ⚫
* De-H2O Bake (eg. 220°C, 1m+). Optionally Oxygen ash instead.
⚫
PEii Technics O2: 30sec. May increase feature openings.
  
  ⚫
* HMDS soak 10s+
  ⚫
* Spin PMGI SF-5 @ 4krpm (rcp 7)
  ⚫
** --> POLOS underside clean: 2000rpm, ACE/ISO/N2
  +
* PMGI-Bake: 220°C, 3min (BrewerSci lift-pin hotplate).
  ⚫
** Recipe "'''''00 220deg, 3min Vac'''''". Enable Vacuum with overhead valve, only for wafer landing and then turn off.
  ⚫
* Spin UV-6-0.8 @ rcp 6 (3.5krpm)
  +
** --> POLOS underside clean: 2000rpm, ACE/ISO/N2
  ⚫
* Soft-Bake = 135°C, 1min (builtin hotplate)
  ⚫
* (check underside for particulates)
  ⚫
* ASML Exposure
  ⚫
** -- Default: Exp = 37.5mJ // foc = –0.10
  ⚫
* (Try this exposure dose - might need to do a FocArray (smaller Image Distribution eg. 5x5) to find proper exposure.
  ⚫
* PEB = 135°C, 1.5min (built-in hotplate)
  ⚫
* Dev (300MiF) = 50sec (CRITICAL time)
  ⚫
** --> with cassette & H2O dish prepared
  ⚫
** --> not stirring, instead very slow/gentle lift/drop at various angles or gentle swish
  ⚫
* DI rinse : very Gently! Dunk into prepared DI dish, and dump/fill gently 2x. Don’t allow direct hard water to hit PR surface.
  ⚫
* PEii Technics O2: 30sec. May increase feature openings.
  ⚫
* Metal Evaporation - EBeam#4 or EBeam#1 vertical/4-inch holder
  ⚫
* Lift-off in NMP, facing down or vertical.
   
  +
<br />
⚫
Metal Evaporation - EBeam#4 or EBeam#1 vertical/4-inch holder
  
   
  +
== Examples ==
⚫
Lift-off in NMP, facing down or vertical.
  
  +
<br />

Revision as of 22:15, 6 September 2019

This process is intended for Deep-UV Exposure on the ASML DUV Stepper. PMGI is used as the underlayer, which is exposed at the same time as the imaging resist.

This process uses PMGI SF-5 @ 4krpm, which spins to about 130nm (maximum metal thickness = 130nm/3 ≈ 45nm) and undercuts laterally about 130-140nm (minimum gap between metals = (2 x 140nm) + 30nm ≈ 350nm).

Tips

Please see our [Bi-Layer Lift-Off Tutorial] to understand the limitations and requirements for good lift-off.

  • Remember that gaps in between adjacent metal traces can lift-off during the develop!
  • Need underlayer thickness 2x to 3x the desired metal thickness.
  • The underlayer will develop laterally from both sides which can lift-off the imaging resist, so:
    • Minimum gap between adjacent metals should then be: less than 0.5 * underlayer thickness
    • Want at least 30-50nm of underlayer width left to support the imaging resist, so the PR doesn't fall over/collapse.
  • Make sure to use a vertical evaporation - EBeam4 or EBeam1. EBeam3 is not vertical.


Suggested Process for Liftoff

  • De-H2O Bake (eg. 220°C, 1m+). Optionally Oxygen ash instead.
  • HMDS soak 10s+
  • Spin PMGI SF-5 @ 4krpm (rcp 7)
    • --> POLOS underside clean: 2000rpm, ACE/ISO/N2
  • PMGI-Bake: 220°C, 3min (BrewerSci lift-pin hotplate).
    • Recipe "00 220deg, 3min Vac". Enable Vacuum with overhead valve, only for wafer landing and then turn off.
  • Spin UV-6-0.8 @ rcp 6 (3.5krpm)
    • --> POLOS underside clean: 2000rpm, ACE/ISO/N2
  • Soft-Bake = 135°C, 1min (builtin hotplate)
  • (check underside for particulates)
  • ASML Exposure
    • -- Default: Exp = 37.5mJ // foc = –0.10
  • (Try this exposure dose - might need to do a FocArray (smaller Image Distribution eg. 5x5) to find proper exposure.
  • PEB = 135°C, 1.5min (built-in hotplate)
  • Dev (300MiF) = 50sec (CRITICAL time)
    • --> with cassette & H2O dish prepared
    • --> not stirring, instead very slow/gentle lift/drop at various angles or gentle swish
  • DI rinse : very Gently! Dunk into prepared DI dish, and dump/fill gently 2x. Don’t allow direct hard water to hit PR surface.
  • PEii Technics O2: 30sec. May increase feature openings.
  • Metal Evaporation - EBeam#4 or EBeam#1 vertical/4-inch holder
  • Lift-off in NMP, facing down or vertical.


Examples


Retrieved from "https://wiki.nanofab.ucsb.edu/w/index.php?title=Lift-Off_with_DUV_Imaging_%2B_PMGI_Underlayer&oldid=156658"