Flash memory devices and methods for fabricating same
Flash memory devices and methods for fabricating the same are provided. In accordance with an exemplary embodiment of the invention, a method for fabricating a memory device comprises the steps of fabricating a first gate stack and a second gate stack overlying a substrate. A trench is etched into the substrate between the first gate stack and the second gate stack and a first impurity doped region is formed within the substrate underlying the trench. The trench is filled at least partially with a conductive material.
1. A memory device comprising:
a plurality of first gate stacks and a plurality of second gate stacks overlying a substrate, wherein the plurality of first gate stacks are disposed in a linear manner along a length of the substrate and the plurality of second gate stacks are disposed in a linear manner along the length of the substrate parallel to the plurality of first gate stacks;
a conductor disposed within a trench in the substrate between the plurality of first gate stacks and the plurality of second gate stacks, wherein the conductor and the trench extend along the length of the substrate; and
a first impurity doped region disposed comprising first and second parts wherein the first part is formed adjacent the sides of the trench and the second part is formed within the substrate underlying the trench and the conductor, wherein the first impurity doped region extends along the length of substrate.
2. The memory device of claim 1 , wherein the conductor comprises tungsten, a metal silicide or a polycrystalline silicon.
3. The memory device of claim 1 , further comprising gate spacers disposed along sidewalls of each of the plurality of first gate stacks and each of the plurality of second gate stacks.
4. The memory device of claim 3 , wherein each of the plurality of first gate stacks and the plurality of second gate stacks comprises a charge trapping layer overlying the substrate and a control gate overlying the charge trapping layer.
5. The memory device of claim 4 , wherein the gate spacers have a thickness sufficient to electrically isolate the conductor from the charge trapping layers of each of the plurality of first gate stacks and a plurality of second gate stacks.
6. The memory device of claim 4 , further comprising an insulating material overlying the conductor and between the plurality of first gate stacks and the plurality of second gate stacks and a word line disposed overlying the insulating material and perpendicular to the first impurity doped region.
7. The memory device of claim 6 , wherein the gate spacers have a thickness sufficient to prevent breakdown between the word line and the control gate of each of the plurality of first gate stacks and the plurality of second gate stacks.
8. The memory device of claim 1 , further comprising a second impurity doped region disposed within the substrate, wherein the second impurity doped region extends along the length of substrate and is shallower than the first impurity doped region.
9. A memory device comprising:
a plurality of first gate stacks and a plurality of second gate stacks overlying a substrate, wherein the plurality of first gate stacks are disposed in a linear manner along a length of the substrate and the plurality of second gate stacks are disposed in a linear manner along the length of the substrate parallel to the plurality of first gate stacks;
a first impurity doped region disposed within the substrate between the plurality of first gate stacks and the plurality of second gate stacks along the length of substrate comprising first and second parts wherein the first part is formed adjacent the sides of a trench and the second part is formed within the substrate underlying the trench;
a second impurity doped region disposed within the substrate between the plurality of first gate stacks and the plurality of second gate stacks along the length of substrate, wherein the second impurity doped region is disposed deeper within the substrate than the first impurity doped region; and
a conductor disposed overlying the substrate between the plurality of first gate stacks and a plurality of second gate stacks, wherein the conductor extends along the length of the substrate and is in electrical contact with the first and second impurity doped regions.
10. The memory device of claim 9 , wherein the conductor is formed of tungsten, metal silicide, or polycrystalline silicon.