CAPACITOR STRUCTURE FOR NON-VOLATILE MEMORY, BASED ON GERMANIUM NANOCRYSTALS IMMERSED IN SILICON DIOXIDE

摘要

The invention relates to a capacitor structure for a non-volatile memory, based on Ge nanocrystals immersed in SiOand to a process for preparing the same, said structure being meant to be used in microelectronics. The structure, as claimed by the invention, consists of a number of three layers deposited on a carrier wafer (1) of Si (100), of type p, with a resistivity ranging between 5...15 Ω x cm, as follows: a SiOtunnel layer (2) with a size ranging between 3...6 nm, a layer (3) of Ge nanocrystals in SiO, with a size ranging between 7...8 nm and a last SiOcontrol layer with a size ranging between 20...25 nm. The process, as claimed by the invention, has the following steps: cleaning the Si carrier wafer (1) with a Piranha solution at 65°C, treating with ultrasounds in deionized water for 45 min, then immersing it into a HF diluted solution for 15...60 s, drying in a flow of N; thermally growing the SiOtunnel layer (2) at a temperature ranging between 950...1000°C by rapid thermal oxidation, under a mixed atmosphere of Ar and O; depositing the Ge intermediate layer (3) and SiOcontrol layer (4) under Ar atmosphere, at a working pressure of 4 mTorr, using magnetron sputtering, followed by a thermal treatment in Ar, at a temperature of 1000°C, for forming the intermediate layer with Ge nanocrystals, with a density in the range of 10cm, immersed in SiO.