Thursday, November 11, 2010

US Patent 7829935 - Si quantum dot flash memory

In recent years there have been efforts by companies such as Micron and Samsung to use quantum dots (i.e. semiconductor nanocrystals) in the floating gate of flash memory cells to facilitate scaling. This patent from Hiroshima University in Japan teaches one variety of such structures based on metal silicide core and silicon shell quantum dots. Claim 1 reads:

1. A semiconductor memory having a floating gate structure, comprising:

a charge storage node including first quantum dots and storing electrons; and

a control node including second quantum dots, injecting electrons to the charge storage node and emitting the electron from the charge storage node;

wherein each of the first quantum dots includes a core layer and a clad layer which covers the core layer; and

the electron occupied level in the core layer is lower than that in the clad layer.