photomasksmyplace.frontier.com/~stevebrainerd1...fwhm : note at 4x. mask blanks use standard i-line...
Post on 07-Jul-2020
1 Views
Preview:
TRANSCRIPT
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
3
Photomasks
• Photomasks• Substrates: Type : thermal expansion• Chrome• Pellicles• Mask: OPC and PSM• Fabrication: E-Beam or Laser
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
4
Photomasks
• Photomask Information Websites:• http://www.photronics.com/internet/corpcomm/publications/basics101/basics.
htm#section3• http://www.appliedmaterials.com/products/etec_tp.html• http://www.photomask.com/tech/ov.html• http://www.lrsm.upenn.edu/~frenchrh/phase_shift_photomasks.htm• http://www.numeritech.com/nttechnology/• http://www.siliconductor.com/equipment/photo.htm• http://courses.nus.edu.sg/course/phyweets/Projects98/litho-x-
e/mask.html
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
5
Photomaskshttp://www.amat.com/products/about_advanced_maskmaking_process2.html
• Photomask Making:
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
6
Photomasks• Photomask Evolution Compexity and Price$• $500- $1000 $1200- $50000
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
7
PhotomasksSubstrates: Type : Blanks
• There are four types of material used to make photomasks; quartz (the most commonly used and most expensive), LE, soda lime, and white crown. The mask sizes can range from 3 inches square to 7 inches square and 7.25 inches round. The thickness of the masks ranges from 60 mils to 250 mils. Most common size for modern tools is 6 inches square 250 mils thick (older tools 5 inch) The quartz has an absorbing film which need to be conductive for e-beam exposure:
• Binary masks: AR:Chrome oxide 100A (~1%) , Absorber:Chrome 800A, Glue and conductive layer ITO 100A (transparent conductor)0.1% Transmission (ND 3.0)
• APSM : MoSi2: 6 – 8% transmission• Weak phase shift or• Halftone masks
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
8
PhotomasksSubstrates: Glass properties : Thermal Expansion
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
14
PhotomasksSome Key layout terms on masks: FIDUCIALSFiducials are patterns on reticles used for alignment on wafer steppers. Each brand and model of stepper has specific types of fiducials. The fiducials are located outside of the array or fields.
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
15
PhotomasksPellicles: Defect protection: Particles outside depth of field
Film membrane: Nitrocellulose
Fluoro-Polymer ( DuPontTeflon
AR coatings
Membrane Thicknesses:
2.85um: ghi line
1.20 um: DUV ghi line
0.794 um: ghi line
0.84 um: DUV ghi line
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
17
PhotomasksOPC
Most common effect: line end shortening
• Typical OPC:• Optical Proximity Correction:• Purposely distort mask pattern to
correct for Proximity effects in wafer patterns caused by :
• Optical : diffraction and interference effects: illumination
• Wafer topographical: Underlying features
• Etch effects: Etcher type and chemistry
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
18
PhotomasksOPC
• Optical Proximity Correction features:• Line end extensions• Line width biasing: Inflation or reduction• Serifs: To square up line ends and corners• Hammerheads: To square up and bias line ends• Sub-resolution outriggers: to correct outside linewidth
proximity effects in dense linewidths
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
19
PhotomasksOPC
• Sub-resolution outriggers: Sub-Resolution Assist Features: SRAF
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
20
PhotomasksOPC Special features
• Serifs: To square up line ends and corners• Sub-resolution outriggers:
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
21
PhotomasksOPC Special features
Line end extensionsLine width biasing: Inflation or reductionSerifs: To square up line ends and cornersHammerheads: To square up and bias line ends
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
24
Photomasks OPChttp://www.mentor.com/dsm/tpapers/vtr.pdf
OPC
on reticle
(chrome)
Un corrected Corrected OPC
OPC pattern on 3 different ReticleWriters = RWA,B,C
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
25
PhotomasksPSM
• PSM: Phase Shift Mask Alternating Aperture type AAPSM
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
27
PhotomasksPSM
• AAPSM:Phase Shift Mask CD optimization 0 and π windows
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
28
PhotomasksFabrication Tools
http://www.appliedmaterials.com/products/pdf/211654exara.pdf• Ebeam
9/11/2004 ECE580-MPE/MASKS/PHOTOMASKS.PPT
31
Photomasks Laser Fabrication Tools:AMAT ETEC http://www.amat.com/products/
Applied Materials Corp. Etec Laser Writers:
Alta 3700 :Exposure: raster scanned 363 nm laser to “ write” masks or reticles down to 0.27u spot size FWHM : note at 4X. Mask blanks use standard I-linephotoresist and processing.
Alta 4000 :Exposure: raster scanned 257 nm laser to “ write” masks or reticles down to 0.19u spot size FWHM: note at 4X. Mask blanks use standard DUV CAR photoresist and processing.
top related