Optical Proximity Correction Article Index for
Optical 		Website Links For
Optical 		 

Information About

Optical Proximity Correction
  CATEGORIES ABOUT OPTICAL PROXIMITY CORRECTION
   
electronic design automation
   
APPAREL
BABY
BEAUTY
BOOKS
CAR TOYS
CELL PHONES
DVD'S
ELECTRONICS
GOURMET FOOD
GROCERIES
HEALTH & PERSONAL
HOME & GARDEN
JEWELRY
MUSIC
MUSIC INSTRUMENTS
OFFICE PRODUCTS
SOFTWARE
SPORTING GOODS
TOOLS & HARDWARE
TOYS
VIDEO GAMES
SHOPPING HOME
MORE SHOPPING...




IMPACT OF RESOLUTION: THE K1 FACTOR

  • wavelength/NA, where NA is the Numerical Aperture . It is often common to compare the critical feature width to this value, by defining a parameter, k1, such that feature width = k1---wavelength/NA. Nested features with k1<1 benefit less from OPC than isolated features of the same size. The reason is the spatial frequency spectrum of nested features contains fewer components than isolated features. As the feature pitch decreases, more components are truncated by the numerical aperture, resulting in greater difficulty to affect the pattern in the desired fashion.



IMPACT OF SPATIAL COHERENCE

  • wavelength/(sigma---NA) [2 . Two image points separated by more than this distance will effectively be uncorrelated, allowing a simpler OPC application. This distance is in fact close to the Rayleigh criterion for values of sigma close to 1.



IMPACT OF MULTIPLE EXPOSURE

As the k1 factor has been steadily shrinking over the past technology generations, the possibility of utilizing multiple exposures to generate circuit patterns becomes more real. This approach will affect the application of OPC, as one will need to take into account the sum of the image intensities from each exposure. This is the case for the complementary PSM technique {Link without Title} , where the images of an alternating-aperture phase-shifting mask and a conventional binary mask are added together.


IMPACT OF MULTIPLE-ETCH PATTERNING

In contrast to multiple exposure of the same photoresist film, multiple layer patterning entails repeated photoresist coating, deposition, and etching to pattern the same device layer. This gives an opportunity to use looser design rules to pattern the same layer. Depending on the lithography tool used to image at these looser design rules, the OPC will be different. Multiple-etch patterning may become a popular technique for future technology generations. A specific form of multiple-etch patterning, using sidewall sacrifical features, is currently the only demonstrated way of systematically patterning features less than 10 nm {Link without Title} . The minimum half-pitch corresponds to the deposited thickness of the sacrificial feature.


OPC APPLICATION TODAY

Today, OPC is rarely practiced without the use of commercial packages from vendors such as Mentor Graphics , Synopsys , Cadence , and MaskTools . It should be noted that the use of OPC is not restricted to the low k1 features which are commonly encountered today, but to any desired image correction scheme which can be modeled accurately. Proximity Effect correction in Electron Beam Lithography is a prime example.


EXTERNAL LINKS



REFERENCES

# K. Ronse et. al., J. Vac. Sci. and Tech. B, vol. 12, pp. 589-600 (1994).
# B. E. A. Saleh and M. C. Teich, ''Fundamentals of Photonics'', pp. 364-5 (Wiley, 1991).
# M. E. Kling et. al., Proc. SPIE vol. 3679, pp.10-17 (1999).
# Y-K Choi et. al., J. Phys. Chem. B, vol. 107, pp. 3340-3343 (2003).