1. Nanofabrication
Nanofabrication manipulates very small materials (< 100 nm)
Examples of nanofabrication
Semiconductor chip in your smartphone and other electronics.
Man made structures that mimic the nano-structures in Nature.
Lab on a chip that shrinks clinic chemistry facilities into handheld devices
The size of an atom is about 0.1 to 0.5 nm
The size of an apple is about 7.0 to 8.3 cm
“…if an apple is magnified to the size of the earth, then the atoms in the apple are approximately the size of the original apple.”
-- Richard Feynman
The apple image downloaded from

2. Nanofabrication makes microelectronic chips
Transistor, the on/off switch
Apple A7 chip includes over 1 billion transistors on a die 102 mm2 in size.
1138 nm
Transistor-Level Image of the Apple A7
Chipworks

3. Microelectronic chips have billions of nano-transistors
Phil. Trans. R. Soc. A (2012) 370, 3950–3972
Imagine building 1 billion houses, including their water, gas, sewage, telephone lines, cables, roads, and highway systems all on your finger nail. How would you do it?
Cu metallization characteristic of a six-level structure associated with a production 32-bit RISC Processor in the CMOS 7S technology. (Courtesy of T Way, IBM
Microelectronics Division, Burlington, VT.)

4. The nanostructure on the butterfly wing can be mimicked using nanofabrication
Blue Morpho butterfly
Radwanul H. Siddiquea,
Karlsruhe Institute of Technology
proceedings.spiedigitallibrary.org
Rene Lopez, UNC at Chapel Hill
Journal of Vacuum Science & Technology B 30, (2012);

5. Nanofabrication can shrink clinical chemistry laboratories to the size of handheld devices
Clinical lab to handheld device enabled by nanofabrication

6. Nanofabrication is only limited by our imagination

7. Photolithography: A key process to make small things over large areas
Create a Designed pattern
on a transparent substrate
(Mask)
Put photoresist on wafers
Shine a light to change
the photoresist
The pattern replicated in
photoresist after developer wash
(Cartoons taken from ASML presentation slides)

8. Positive photoresist and negative photoresist
UV light
Mask blocks UV light at some areas
Photoresist only exposed where UV passes
Substrate
Light increases solubility in positive resist
Light decreases solubility in negative resist

9. How can light change a material’s solubility
Light is electromagnetic radiation with energy Ep=h
Absorption of electromagnetic radiation can move an electron to an excited state, which may trigger a chemical change.
When the electromagnetic radiation is strong enough, the absorption of the radiation can directly remove an electron from the molecule, which is a chemical change.
The chemical changes can change material’s solubility.
nucleus
n=1 , E1
n=2, E2
n=3, E3
Electron in an excited state
Absorption of electromagnetic radiation
Ionization
E = h or
Chm Explain the emission of electromagnetic radiation in spectral form in terms of the Bohr model.

10. An example of positive photoresist
Photoresist before exposure to UV light +
Insoluble in base solution
UV light + H2O
Photoresist after exposure to UV light +
Soluble in base solution

11. An example of negative photoresist
All negative photoresists function by light induced cross-linking of a photosensitive agent. By cross-linking the long polymer chain the solubility in the developer is reduced.
J. Chem. Educ., 1979, 56 (8), p 541