A novel, aerosol-nanocrystal floating-gate device for non-volatile memory applications - Electron Devices Meeting, 2000. IEDM Technical Digest. International

This paper describes the fabrication, and structural and electrical characterization of a new, aerosolnanocrystal floating-gate FET, aimed at non-volatile memory (NVM) applications. This aerosolnanocrystal NVM device features prograderase characteristics comparable to conventional stacked gate NVM devices, excellent endurance (>lo5 P/E cycles), and long-term non-volatility in spite of a thin bottom oxide (55-60A). In addition, a very simple fabrication process makes this aerosol-nanocrystal NVM device a potential candidate for low cost NVM applications. Introduction The memory operation of the aerosol-nanocrystal floating-gate FET depends on charge storage, similar to conventional stacked-gate NVM devices [l]. In a nanocrystal NVM device, however, charge is not stored on a continuous floating-gate poly-Si layer, but instead on a layer of discrete, crystalline Sinanocrystals [2-41. As compared to conventional stacked-gate NVM devices, nanocrystal chargestorage offers several potential advantages such as: (1) simple, low cost device fabrication (no dual-poly process complications); (2) better retention (resulting from Coulomb blockade and quantum confinement effects fS]), enabling thinner tunnel oxides and lower operating voltages; ( 3 ) improved anti-punchthrough performance (due to the absence of drain to floating gate coupling, thereby reducing drain induced punchthrough), allowing higher drain voltages during read-out, shorter channel lengths and, consequently, a smaller cell area; and (4) excellent immunity to stress induced leakage current (SILC) and defects due to the distributed nature of the charge storage in the nanocrystal layer.