Protein-mediated assembly of nanocrystal floating gate in a vertical flash cell

This article proposes and demonstrates a technique of protein-mediated assembly of nanocrystal floating gate in a vertical flash memory cell. The gate-all-around (GAA) vertical design can enable the theoretical minimum cell size of 4F², where F is the minimum lithographic pitch, along with a lithography-independent channel length (Pein et al., 1993), thus helping circumvent the scaling density limitations of planar flash technology (Atwood, 2004). The protein-mediated assembly of preformed nanocrystals enables good ordering and control over nanocrystal size and density, reducing threshold variation across cells for improved manufacturability (Silva, 2003). Physical characterization of the ordered nanocrystal floating gate and electrical characterization of the fabricated memory transistor is presented in this paper.