Mask Fabrication

A mask is necessary for an expositon with a maskaligner or a stepper. It is typically made of a transparent substrate, coated with an opaque metal layer. The layout is transferred into the metal layer, where the light won’t pass while the clear areas allow light to pass through during exposure. The transfer is performed with a photolithography on a laser writter or ebeam (not available at CMi) and an etching step.

In CMi, we work with :

  • Substrate :
    • Soda-lime glass : broadband, i-line, g-line (UV light)
    • Quartz glass : DUV
  • Metal layer :
    • Low Reflective Chromium (LRC)
  • Dimensions :
    • 5” to expose 4” wafer
    • 6” to expose in the DUV Stepper
    • 7” to Expose 6” wafer


CMi Ordering interface

  • Chrome Blank 5” or 7” :
    • Soda-lime glass
    • Thickness : 2.3mm
    • LRC
    • coated with 530nm of AZ1512HS
  • Quartz Chrome Blank 5” or 6” :
    • Quartz glass
    • Thickness : 5” – 2.3mm / 6” – 6,35mm
    • LRC
    • coated with 530nm of AZ1512HS


Fabrication

1. Exposure

It is important to remember to :

  • Check the polarity desired and invert if necessary
  • Y-axis reflection (The mask is fabricated with the LRC on top but it is used upside-down)

Equipment :

  • VPG200 (Z5, CD : 800nm, 1000nm, 2000nm)
  • MLA150 (Z16, CD : 1000um) – Backup option

 

2-4. Development + Etching + Stripping  

Equipment :

 

For DUV Stepper reticle fabrication, please contact the staff for more information (design restriction, mandatory alignement marks, etc..)

 

Inspection :

  • Chrome blank 5” and 7”, Quartz Chrome blank 5”
    • Optical microscope
    • SEM
  •   Quartz Chrome blank 6” (Stepper reticle)
    • It should never be inspect on a tool if it is still supposed to go in the stepper !!!
    • For inscpection, expose the same design on a dummy Chrome blank 7”