Projection lithography uses an optical system to focus and project a mask image onto a silicon wafer. There are three main types: scanning projection which moves the mask and wafer, step and repeat which replicates a larger mask pattern across the wafer, and step and scan which scans the mask while moving the wafer. Projection lithography allows for higher resolution than contact lithography without damaging masks. It enables mass production of integrated circuits with feature sizes below 100nm.

1. PROJECTION
LITHOGRAPHY
BY MUHAMMAD FARZAM UDDIN

2. CONTENTS
• INTRODUCTION
• SYSTEMATIC FIGURE
• TYPES OF PROJECTION PRINTING
• ADVANTAGES
• CONCLUSION

3. Introduction
• Development lies between in mid 1980’s.
• An optical system focuses on the light
source and reduce mask image for
exposure on the surface.
• Some distance between mask and wafer.
• System focus to insert image of mask on
wafer.
• Not a single step revealing process.

4. Systematic view of optical projection
system
https://ir.nctu.edu.tw/bitstream/11536/80472/1/155801.pdf

5. Types of
projection
printing
There are three types
following:
Scanning projection printing
Step and Repeat projection
printing
Step and Scan projection
printing

6. Scanning projection printing
• The mask and wafer in the motion
• Use better optics
• No reduction of mask
• Alignment accuracy is hard to improve because of
mechanical motion
https://www.spiedigitallibrary.org/ebooks/FG/Field-Guide-to-Optical-Lithography/Processing-Alignment-and-Exposure/Processing-Alignment-and-
Exposure/10.1117/3.665802.p6?SSO=1

7. Step and Repeat projection printing
• Reduction of mask size
• Bigger pattern on mask
• Resolution limit to about 0.35uM
• Cadiotropic system
• More reptation are required to cover whole wafer,
Therefore, more time will be consumed.
https://iopscience.iop.org/book/978-0-7503-2608-7/chapter/bk978-0-7503-2608-7ch2

8. Step and Scan projection printing
• Mask is scanned by optical system and wafer move so
to expose
• Lens system variation minimized
• Use spherical mirror and scanning pattern
• Better than other techniques
https://iopscience.iop.org/book/978-0-7503-2608-7/chapter/bk978-0-7503-2608-7ch2

9. Advantages
No damage to mask compare to contact lithography
High resolution compare to proximity lithography
Low production cost
Ease production of smaller dimension pattern
Improved mass production

10. Conclusio
n
Smaller resolution
Lens system reduces
diffraction error
Decreasing wavelength and
increasing NA good resolution
Features smaller than 100nm
achieved in production line

11. THANK
YOU!