Non-volatile memory (NVM) cell
View Patent ↗A method of forming a flash memory cell includes forming a first hard mask and a second hard mask on a substrate. A select gate is formed as a spacer around the first hard mask. A charge storage layer is formed over the first and second hard masks and the select gate. A control gate is formed as a spacer around the second hard mask. A recess in the control gate is filled with a dielectric material. The recess is formed between a curved sidewall of the control gate and a sidewall of the charge storage layer directly adjacent the curved sidewall of the control gate.
1. A semiconductor structure comprising:
a substrate;
a select gate formed on the substrate;
a control gate formed on the substrate;
a charge storage layer formed between a sidewall of the select gate and a first sidewall of the control gate; and
a dielectric material formed between a portion of the control gate and a portion of the charge storage layer, wherein the dielectric material is positioned to separate a contact portion of the control gate from a contact portion of the select gate.
2. The semiconductor structure of claim 1 wherein the charge storage layer includes:
a bottom dielectric layer formed along the sidewall of the select gate and a channel region of the substrate under the control gate;
a layer of charge storage elements formed on the bottom dielectric layer; and
a top dielectric layer formed over the layer of charge storage elements.
3. The semiconductor structure of claim 1 wherein a height of a portion of a top surface of the control gate is the same as a height of a portion of a top surface of the select gate.
4. The semiconductor structure of claim 1 wherein:
the dielectric material is formed in a recess portion in one side of the control gate adjacent the charge storage layer.
5. The semiconductor structure of claim 1 , wherein:
the select gate is formed as a spacer using polysilicon material.
6. The semiconductor structure of claim 5 , wherein:
the control gate is formed as a spacer using polysilicon material.
7. The semiconductor structure of claim 1 wherein:
the semiconductor structure is a flash memory cell.
8. The semiconductor structure of claim 7 further comprising:
a curved portion of a sidewall of the select gate faces a curved portion of a second sidewall of the control gate, wherein the sidewall of the select gate and the curved portion of the second sidewall of the control gate are separated by the charge storage layer.
9. The semiconductor structure of claim 8 wherein the charge storage layer extends along a third sidewall of the control gate.