1. BY
SURAJ MENON
S7,EEE,61

2. outline Lithography Introduction to EUVL Basic concepts
Why do we need EUVL?
EUVL Process
Basic technology for EUV
EUV masks
All Reflective Optics
Advantages
Disadvantages
Conclusion

3. WHAT IS LITHOGRAPHY
Lithography is akin to photography in that it uses light to transfer images onto a substrate
The term lithography is derived from the words ‘lithos’ meaning stone and ‘graphy’ meaning write.
Our stone is silicon wafer and writing is done using a photo sensitive polymer.

4. INTRODUCTION
Extreme ultraviolet lithography is an advanced technology for making microprocessors a hundred times more powerful than those made today.
Optical projection lithography has been the lithographic technique used in the high-volume manufacture of integrated circuits.
The key to creating more powerful microprocessors is the size of the light's wavelength.

5. BASIC CONCEPT BEHIND EUV
Minimum lithographic feature size =
k1: “Process complexity factor”
λ: Exposure wavelength
NA: Numerical aperture of the lens.Higher NA means smaller depth of focus.
k1*λ NA

6. WHY EUVL EUVL is required for the continuity of Moore’s law
The number of transistors that can be placed inexpensively on an integrated circuit doubles approximately every two years.
EUVL is a next generation lithography technique.

8. EUVL Glass lens replaced by mirrors…. λ= 13.5nm…
Reflective masks are to be used.
more power…faster mp
This wafer was patterned on a prototype device using extreme-ultraviolet lithography (EUVL).

9. Euvl process Laser is directed to a jet of xenon gas to produce plasma
To create the IC, light is directed to a mask.
Light reflects from the mask then through a series of mirrors that shrinks the image down.
Projected to wafer covered with photoresist
Light hardens the photoresist.
Region not exposed remain gooey and the remaining is hardened photoresist and exposed silicon wafer.

11. BASIC TECHNOLOGY FOR EUV
All solids, liquids, and gases absorb 13.5nm – so system is under vacuum
Mask must be reflective and exceptionally defect-free
13.5nm photons generated by plasma source
All-reflective optics
(all lens materials are opaque)

12. EUV MASKS

13. All-Reflective Optics
All solids, liquids, and gases absorb 13.5nm photons
So fused silica lenses are OUT …
Indeed, all refracting lenses are OUT
Making EUV mirrors is no cakewalk, either …
50 or more alternating Mo/Si layers give the mirror its reflectivity
Each layer is 6.7nm thick and requires atomic precision
Since the angle of incidence changes across the mirror, so do the required Si layer thicknesses
Net reflectance: ~70%

14. IMAGE FORMATION
Top: EUV multilayer and absorber constituting mask pattern for imaging a line.
Bottom: EUV radiation reflected from the mask pattern is absorbed in the resist and substrate, producing photoelectrons and secondary electrons.
These electrons increase the extent of chemical reactions in the resist.

15. EUVL ADVANTAGES Microprocessors made by euvl are up to
to 100 times faster than today's most powerful chips
Decrease in size of chip but the speed increases.
EUVL technology achieves good depth of focus and linearity for both dense and isolated lines with low NA.
Increase in storage capacity.
The low thermal expansion substrates provide good image placement.

16. EUVL DEFECTS Positive charging, due to ejection of photoelectrons
Contamination deposition on the resist from out gassed hydrocarbons, which results from EUV- or electron-driven reactions.
No known method for repairing defects in a ML coating.
Entire process has to be carried out in vacuum.
Mirrors used are only 70% reflective.

17. CONCLUSION EUVL will opens a new chapter in semiconductor technology.
Successful implementation of EUVL would enable projection lithography to remain semiconductor industry’s pattern technology of choice for years to come.
Much work is to be done in order to determine whether EUVL is ready for large scale production.

18. REFERENCES
Sang Hun Lee, Yashesh Shroff, Manish Chandhok. Flare and Lens Aberration Requirements for EUV Lithographic Tools. Proceedings of SPIE, Volume 5751, Emerging Lithographic Technologies IX, May Pages 707–714.
Euv lithography- vivek bakshi
A complete course of lithography by Alois.