Difference between revisions of "Optical Lithography Resources"

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! Resist !! Wafer Prep !! Spin !! Thickness !! Prebake !! Exposure !! Postbake !! Development  !! Hardbake !! Lamp !! Notes  
! Resist !! Wafer Prep !! Spin !! Thickness !! Prebake !! Exposure !! Postbake !! Development  !! Hardbake !! Lamp !! Notes  
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| 2050 || Dehydrate on hot plate || 3000rpm || 50μm || 65C 3min 95C 9min || X || 65C 2min 95C 7min || SU-8 Developer X seconds || Optional || Suss1 Ch1 15mW/cm^2 || Measured 10/19
| 2050 || Dehydrate on hot plate || 3000rpm || 50μm || 65C 3min 95C 9min || X || 65C 2min 95C 7min || SU-8 Developer X seconds || Optional || Suss1 Ch1 || Measured 10/19
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Revision as of 16:35, 4 December 2019

Trove of lithography application notes from MicroChemicals covering troubleshooting, procedures, techniques, theory

KNI Photoresists

Photoresists provided by KNI:

  • S1805, 1813, 1818: field standard positive, may be used for liftoff and withstands some acid etching. Designed with lower toxicity materials. (Manufacturer Spec Sheet) Shipley 1800 series 0.5-1.9μm range available. 0.5-3.2μm available from manufacturer
  • AZ 5214: exposable as positive and image reversal negative. Optimized for liftoff processes with negative sidewall profile. Structure is stable to 130°C after postbake. 1-2μm thickness (Manufacturer Spec Sheet)
  • AZ 9245, 9260: Intended for thick positive structures 4-20μm. Lower optical absorption and sensitivity permits tall structures but development is slow. (Produce Page)
  • AZ nLof 2020, 2035, 2070: Also optimized for liftoff processes but thicker than 5214 at 2-7μm spinnable. Structures are stable to 250°C. High chemical stability, e-beam exposable, but more difficult to remove. (Product Page)
  • AZ 3330-F: medium resolution resist, high thermal stability, optimized for metal RIE etch or plating process environments. 1.0-5.0µm spinnable (Product Page)
  • AZ 4620: improved surface adhesion for etching and plating applications, photosensitivity is broad and low, spinnable to 6 - 20 µm.
  • SU-8 2002, 2025, 2075, 2100, 3025, 3050: epoxy-based negative resist. Optimal for tall high-aspect ratio permanent structures. (Manufacturer Spec Sheet ). Difficult to remove. Spinnable to 1.5-200μm thickness.


Reminder of lamp intensities:

Suss 1 Exposure Settings

  • Channel 1 is 365nm wavelength at 15 mW/cm2.
  • Channel 2 is 405nm wavelength at 25 mW/cm2.

Suss 2 Exposure Settings

  • Channel 1 is 365nm wavelength at 10 mW/cm2.
  • Channel 2 is 405nm wavelength at 15 mW/cm2.

Positive Photoresist Recipes

See recipe notes for additional information on wafer cleaning and prep, edge bead removal, and spin curves.

Resist Wafer Prep Spin Thickness Prebake Exposure Postbake Flood Development Hardbake Lamp Notes
S1813 Dehydrate on hot plate 3000rpm 1.5μm 115C 1min X - - X - Suss1 Ch1 Measured 10/19 (Link KNI recipe doc here)
AZ5214 Dehydrate on hot plate 3500rpm 1.4μm 100C 1min 25s - - MF319 60s - Suss1 Ch1 Measured 10/19

Negative Photoresist Recipes

See recipe notes for additional information on wafer cleaning and prep, edge bead removal, and spin curves.

Resist Wafer Prep Spin Thickness Prebake Exposure Postbake Flood Development Hardbake Lamp Notes
AZ5214 Dehydrate on hot plate 2000rpm 1.8μm 100C 1min 12s 110C 1min 40s MF319 60s - Suss1 Ch1 Measured 10/19
Dehydrate on hot plate 3500rpm 1.4μm 100C 1min 9s 110C 1min 30s MF319 60s - Suss1 Ch1 Measured 10/19
nLoF 2070 Dehydrate on hot plate 2500rpm 7um 110C 90s 12s 110C 90s - AZ 726 2min - Suss1 Ch1 Measured 10/19

SU-8 Recipes

SU-8 is available in thicknesses ranging from 500nm to 500microns. Remember to use Laurel Spinner 1.

BYU SU-8 Guide

Resist Wafer Prep Spin Thickness Prebake Exposure Postbake Development Hardbake Lamp Notes
2050 Dehydrate on hot plate 3000rpm 50μm 65C 3min 95C 9min X 65C 2min 95C 7min SU-8 Developer X seconds Optional Suss1 Ch1 Measured 10/19

Other Photoresists

Non-KNI Photoresist Recipes

Resist Wafer Prep Spin Thickness Prebake Exposure Postbake Flood Development Hardbake Lamp Notes
SPR 220-7.0 - - - - - - - - - - Measured 10/19

KNI Developers

Developers provided by KNI:

  • AZ 726 MIF: 2.38% TMAH-based, pre-diluted (ready-to-use) and slightly further diluted only when the application requires it. Contains surfactants to improve development uniformity, so avoid stirring. MIF identifies the developer as 'Metal Ion Free' as it does not contain potassium as in KOH-based developers, it is based on TMAH, an ammonium salt, which prevents metal contamination of semiconductors. 726 is a recommended developer for almost all AZ resists MicroChemicals Development Application Note
  • Microposit MF 319: (Metal-Free) TMAH: 2.45%, Polyalkylene glycol <1%, pH: 13. Paired to Shipley/Microposit 1800 series resists, S1805,S1813,S1818 MSDS
  • Microposit CD-26: TMAH <5.0 % , pH 13, Also 1800 series targeted, no additional surfactants.
  • AZ 400K: KOH-based. "The recommended dilutions for the AZ® 400 K or AZ® 351 B for most of the processes are developer concentrate : Water = 1: . For very thick resist films, up to a 1:3 ratio can be applied [with lower contrast], with a very fine (sub-µm) structures, a 1:5 or 1:6 ratio can support a high resolution using thin resist films." Ref: MicroChemicals Development Application Note Users can adjust dilution for accuracy and length of time they will tolerate.
    • Critical note on KOH use: "Incompatibilities between MIC and MIF Developers Even small traces of TMAH-based metal ion-free developers such as the AZ® 326 MIF, 726 MIF or 826 MIF) can significantly reduce the development rate of metal ion-containing developers (such as the AZ® 400K or 351B). If both types of developers are used, extremely clean work is to be ensured to prevent mutual contamination even in the ppm range, such as in the dispensing system or developer containers." Ref: MicroChemicals Development Application Note
  • Microposit 2401: Legacy developer

Surfactants

Surfactants were developed and added in the 1980s to photoresist developers to combat photoresists' hydrophobic surfaces which cause "hot spots" of fast development. They reduce the surface tension and improve wetting (giving homogeneous development). The common drawback of their inclusion is foaming and an oily nature which makes them incompatible with some agitated processes. Surfactacts also change development speed since they coat photoresist surfaces and inhibit the dissolution reaction. As such exposure-development times must be adjusted and while contrast is improved, resolution may be lost. See here for more in depth discussion: The Lithography Tutor: Photoresist Development

Addtional Photolithography Resources