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Source: Reprinted with permission from [202], T. Cui et al., "Novel Lithography Based Approaches to Pattern Layer-by-Layer Self-Assembled Thin Films," 2002. © 2002, ASME.

Source: Reprinted with permission from [202], T. Cui et al., "Novel Lithography Based Approaches to Pattern Layer-by-Layer Self-Assembled Thin Films," 2002. © 2002, ASME.

film. Capacitors are fabricated on 4-inch P-type and N-type silicon wafers. The measured CV curves are in compliance with typical MOS capacitors. Compared to the traditional process, this has the advantages of low temperature, low cost, and short processing time. The simplicity and reliability of this process to fabricate the simple MOS capacitor provides a new way to fabricate other microelectronic or optoelectronic devices by traditional lithography and LbL, self-assembled building blocks.

Figure 10(a) shows an SEM image of the (45-nm silica/PDDA)4 multilayer cross-section. The film has a permanent thickness of 170 nm, leading to 43 nm for every bilayer close to the silica particle diameter. A film mass from QCM and a film thickness from SEM gives a density of the SiO2/PDDA multilayers as p = 1.43 ± 0.05 g/cm3. To calculate the silica-packing coefficient in the films, it is reasonable to assume that the dry film consists of SiO2, PDDA, and air-filled pores. The mass ratio of PDDA to PDDA/SiO2 bilayer obtained from QCM measurements is 0.08. Taking

Patterned photoresist

Polyion multilayers

Before lift-off

nanoparticle multilayers deposition

Lift off polyion and nanoparticle films above the photoresist with assistance of ultrasonic treatment.

After lift-off

NP film

Before lift-off

After lift-off polyion resist

polyion resist

Figure 9. (a) Scheme of patterning nanoparticle thin films with ultrasonic treatment. (b) Scheme of patterning nanoparticle thin films without ultrasonic treatment. NP and polyion films cannot be lifted off because of the linkage between polyion molecules are not disconnected. Reprinted with permission from [203], F. Hua et al., Nanotechnology 14, 453 (2003). © 2003, Institute of Physics.

Substrate

NP film

(b)

Thickness versus Cycles of Alternate adsorption

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