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Pattern Printers Presentation Transcript
1.LITHOGRAPHY – Part 3
2.Flow diagram for mask generation process
3.MOS Invertor
4.CMOS P-well Inverter Showing Vdd and Vss Connections
5.Layout of the inverter
6.Layout Showing
8 Invertors
7.What are Pattern Printers? These are highly accurate machines used to Align the mask with the image on the wafer Expose the photoresist on the wafer with desired radiation for desired time
8.Types of Printers Contact Printer – The mask is in intimate contact with the wafer Proximity Printer – The mask is in close proximity of the wafer Projection Printer – The mask is optically projected on the wafer
9.X-ray Lithography Wavelength < 5 nm; Higher resolution No materials that can reflect or refract x-rays Must be accomplished by the direct printing process – similar to proximity printing
10.What do we require to transfer the pattern?
11.Quality Inspection Main Purpose – ensure that the pattern on the PR is: not distorted not misaligned does not have incorrect critical dimensions free from surface irregularities such as scratches, pinholes, stains, contaminants
12.An electron microscope is needed for the sub-0.25 micron feature inspection. When the electron beam hits the materials, it can excite secondary electrons. By mapping the detected electric signal from these secondary electrons, the imaging of the tiny feature can be observed,
13.Case (1)
14.Case (2)
15.Resolution Improvement
16.Numerical Aperture
17.Resolution and Depth of Focus
18.Spatial Coherence
19.Spatial Frequency
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