Non-volatile storage element with suspended charge storage region
Suspended charge storage regions are utilized for non-volatile storage to decrease parasitic interferences and increase charge retention in memory devices. Charge storage regions are suspended from an overlying intermediate dielectric material. The charge storage regions include an upper surface and a lower surface that extend in the row and column directions. The upper surface of the charge storage region is coupled to the overlying intermediate dielectric material. The lower surface faces the substrate surface and is separated from the substrate surface by a void. The charge storage region includes a first vertical sidewall and a second vertical sidewall that extend in the column direction and a third vertical sidewall and fourth vertical sidewall that extend in the row direction. The first, second, third, and fourth vertical sidewall are separated from neighboring features of the non-volatile memory by the void. The void may include a vacuum, air, gas, or a liquid.
1. A non-volatile semiconductor memory, comprising:
a substrate;
a plurality of non-volatile storage elements arranged into rows and columns above a surface of the substrate, each non-volatile storage element including a suspended charge storage region having a bottom surface separated from the surface of the substrate by a void;
a plurality of isolation regions formed in the substrate between a plurality of active areas of the substrate;
a plurality of support pillars formed in each isolation region;
a plurality of dielectric strips including a dielectric strip formed for each row of non-volatile storage elements, each dielectric strip having a lower surface coupled to an upper surface of a support pillar in each isolation region; and
a plurality of control gates including a control gate formed over each row of non-volatile storage elements, each control gate being separated from underlying charge storage regions of the row by the dielectric strip for the row.
2. The non-volatile semiconductor memory of claim 1 , wherein:
each support pillar includes four vertical sidewalls;
a first vertical sidewall and a second vertical sidewall of each pillar are separated by a void from one or more charge storage regions adjacent in a direction of the rows; and
a third vertical sidewall and a fourth vertical sidewall of each pillar are separated by a void from one or more of the support pillar that are adjacent in a direction of a the columns.
3. The non-volatile semiconductor memory of claim 2 , wherein:
the suspended charge storage region of each non-volatile storage element includes a first sidewall and a second sidewall extending in the direction of the rows, the first sidewall and the second sidewall of the charge storage region are separated by the void from one or more suspended charge regions that are adjacent in the direction of the columns; and
the suspended charge storage region of each non-volatile storage element includes a third sidewall and a fourth sidewall extending in the direction of the columns, the third sidewall and the fourth sidewall of the charge storage region are separated from one or more suspended charge storage regions that are adjacent in the direction of the rows.
4. The non-volatile semiconductor memory of claim 1 , wherein:
the suspended charge storage region of each non-volatile storage element is stationary within the non-volatile semiconductor memory.
5. The non-volatile semiconductor memory of claim 4 , further comprising:
control circuitry for programming the non-volatile storage elements while the suspended charge storage region is separated from the surface of the substrate by the void.