Memory device and method for using prefabricated isolated storage elements

Abstract

A semiconductor device that includes a floating gate made up of a plurality of pre-formed isolated storage elements ( ) and a method for making such a device is presented. The device is formed by first providing a semiconductor layer ( ) upon which a first gate insulator ( ) is formed. A plurality of pre-fabricated isolated storage elements ( ) is then deposited on the first gate insulator ( ). This deposition step may be accomplished by immersion in a colloidal solution ( ) that includes a solvent and pre-fabricated isolated storage elements ( ). Once deposited, the solvent of the solution ( ) can be removed, leaving the pre-fabricated isolated storage elements ( ) deposited on the first gate insulator ( ). After depositing the pre-fabricated isolated storage elements ( ), a second gate insulator ( ) is formed over the pre-fabricated isolated storage elements ( ). A gate electrode ( ) is then formed over the second gate insulator ( ), and portions the first and second gate insulators and the plurality of pre-fabricated isolated storage elements that do not underlie the gate electrode are selectively removed. A source region ( ) and a drain region ( ) are then formed in the semiconductor layer ( ) such that a channel region is formed between underlying the gate electrode ( ).