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Lithography

Photolithography, lithography, microlithography and nanolithography are all the production of ultra-small three dimensional relief images based on exposure and subsequent development of a photon sensitive polymer called photoresist. Micro and nano prefixes describe the scale of 10e-6 and 10e-9 of a meter of the photoresist features. These photoresist features are used to “resist” etching or ion implantation of the underlying film.

The two main types of tool used to expose the photoresist are based on either contact/proximity printing or projection image printing. Both use a mask (pattern to be transferred) to create the image on the wafer coated with photoresist.

The process steps on the wafer needed for lithography include:

  • Cleaning
  • Dehydration bake
  • Coating of anti-reflective layer
  • Coating of photoresist
  • Post application bake then cool plate
  • Exposure on imaging tool
  • Post exposure bake then cool plate
  • Development of photoresist image
  • Post development bake then cool plate
  • Inspection for critical dimensions (feature size) and defects

Then the wafer is ready to go to processes such as etch, deposition, or ion implant.

After this processing the photoresist image is stripped off the wafer. The wafer is sent on for the next process step.

The Lithography tool set at RIT is used by our students for laboratory classes and projects. The tool set includes manual coating spinners and automated coating tracks, Suss Aligners, GCA stepper and ASML stepper.

Our classes and labs are unique and use the SMFL equipment for undergraduate and graduate education as well as undergraduate and graduate research projects.

Courses using lithography include:

Fall Semester

  • MCEE(101)-Intro. to Nanoelectronics
  • MCEE(201)-IC Technology
  • MCEE(205)-Statistics and DOE
  • MCEE(495)-Senior Design I
  • MCEE(503)-Thin Films
  • MCEE(505)-Lithography Materials & Proc
  • MCEE(601)-Microelectronic Fabrication
  • MCEE(603)-Thin Films
  • MCEE(605)-Lithography Materials & Proc
  • MCEE(770)-Microelectromechanical Systems

Spring semester

  • MCEE(201)-IC Technology
  • MCEE(360)-Semiconductor Dev-MicroE
  • MCEE(496)-Senior Design II
  • MCEE(515)-Nanolithography Systems
  • MCEE(601)-Microelectronic Fabrication
  • MCEE(615)-Nanolithography Systems

To view the detailed equipment links visit the SMFL site: http://www.smfl.rit.edu/

Safety in the SMFL is essential for all users and enables research as well as education of undergraduate and graduate students.