Tunnel oxide prepared by thermal oxidation of thin polysilicon film on silicon (TOPS)

A new simple and reliable method to form a textured Si surface for the fabrication of a tunnel oxide film

“…If oxide film is grown or deposited on this textured Si surface, a rugged SiO /Si interface can be expected. A field enhancement effect at the asperities of the rugged SiO /Si interface of the textured oxide enhances electron injection into oxide film [4], which makes the Fowler-Nordheim (FN) injection occur at lower gate voltages. The lower FN occurred voltage and asymmetry of -characteristics of textured oxide are beneficial for the device applications for low programming voltage application.…”

“…Growing a tunnel oxide film with a textured SiO /Si interface can meet the lower programming voltage requirement. Several methods have been reported to form the tunnel oxide with a textured SiO /Si interface, e.g., by etching the Si surface [1]- [3] or by thermal oxidation of a thin poly-Si film [4]- [6] on the Si substrate. However, there are many problems with the use of these methods.…”

Characterization of thin textured tunnel oxide prepared by thermal oxidation of thin polysilicon film on silicon

“…It has been reported that the TOPS sample has a better immunity to the hot electron stressing than the normal oxide, due to its lower bulk electric field induced by the textured Si/SiO2 interface [14]. In this section, we used the bidirectional I-V measurement [ 181 to study the trapped charge density and the trapped charge centroid.…”

“…Recently, it was proposed that an ultra-thin textured tunnel oxide (5100 A) can be prepared by thermally oxidizing a thin polysilicon film on silicon substrate (TOPS) [14]. Due to the rapid diffusion of oxygen through the grain boundaries of thin polysilicon film into the Si substrate and the enhanced oxidation rate at the grain boundaries, a textured Si/SiOz interface is obtained [ 141.…”

“…The textured interface results in localized high fields and enhances the electron injection into TOPS. Hence, the TOPS sample exhibits a much higher electron conduction efficiency and a much lower electron trapping rate as compared to the normal tunnel oxide, in spite of the substrate doping level [14]. This recipe can also be applied to prepare an ultra-thin textured polyoxide (5100 A)…”