Thickened sidewall dielectric for memory cell
Methods and devices are disclosed, such as those involving memory cell devices with improved charge retention characteristics. In one or more embodiments, a memory cell is provided having an active area defined by sidewalls of neighboring trenches. A layer of dielectric material is blanket deposited over the memory cell, and etched to form spacers on sidewalls of the active area. Dielectric material is formed over the active area, a charge trapping structure is formed over the dielectric material over the active area, and a control gate is formed over the charge trapping structure. In some embodiments, the charge trapping structure includes nanodots. In some embodiments, the width of the spacers is between about 130% and about 170% of the thickness of the dielectric material separating the charge trapping material and an upper surface of the active area.
1. A memory device comprising:
an active area of a semiconductor;
charge trapping material comprising a plurality of nanodots separated from the active area by dielectric material, wherein the dielectric material is configured such that electrons may tunnel through the dielectric material between an upper surface of the active area and the charge trapping material during operation of the memory device; and
a spacer formed from dielectric material and disposed between the charge trapping material and a sidewall of the active area, the spacer substantially preventing electrons from tunneling through the spacer from the sidewalls of the active area to the charge trapping material during operation of the memory device;
wherein the spacer separates the charge trapping material and the sidewall of the active area by between about 110% and about 200% a thickness of the dielectric material between the upper surface of the active area and the charge trapping material.
2. The device of claim 1 , wherein the spacer separates the charge trapping material and the sidewall of the active area by between about 130% and about 170% a thickness of the dielectric material between the upper surface of the active area and the charge trapping material.
3. The device of claim 1 , wherein the thickness of the spacer between the sidewall of the active area and the charge trapping material is about 100 Å or greater.
4. A memory device comprising:
an active area of a semiconductor;
charge trapping material comprising a plurality of nanodots separated from the active area by dielectric material, wherein the dielectric material is configured such that electrons may tunnel through the dielectric material between an upper surface of the active area and the charge trapping material during operation of the memory device; and
a spacer formed from dielectric material and disposed between the charge trapping material and a sidewall of the active area, the spacer substantially preventing electrons from tunneling through the spacer from the sidewalls of the active area to the charge trapping material during operation of the memory device;
wherein the thickness of the spacer between the sidewall of the active area and the charge trapping material is between about 100 Å and about 120 Å.
5. The device of claim 1 , wherein the thickness of the dielectric material between the upper surface of the active area and the charge trapping material is between about 55 Å and about 85 Å.
6. The device of claim 5 , wherein the thickness of the dielectric material between the upper surface of the active area and the charge trapping material is between about 65 Å and about 75 Å.
7. The device of claim 1 , further comprising at least one control gate configured to control a charge of the charge trapping material, the at least one control gate being disposed over the charge trapping material.
8. The device of claim 1 , further comprising a filler covering a lower portion of the sidewalls of the active area.
9. The device of claim 8 , wherein an upper surface of the filler is recessed from the upper surface of the at least one active area by between about 20 Å and about 300 Å.
10. The device of claim 9 , wherein an upper surface of the filler is recessed from the upper surface of the at least one active area by between about 50 Å and about 150 Å.
11. The device of claim 8 , wherein the filler comprises silicon oxide.
12. The device of claim 1 , wherein the sidewalls have a height of between about 1800 Å and about 2200 Å.
13. The device of claim 1 , wherein the active area has a width of between about 325 Å and about 425 Å.