Method for producing semiconductor memory devices and integrated memory device
View Patent ↗The invention provides an integration scheme for a memory cell array, especially a charge-trapping memory cell array, comprising an architecture of local interconnects, which enables to avoid nitride insulations of wordline stacks and to produce CMOS devices of different structures and dimensions in standard technology along with the tinier memory cell transistors.
1. An integrated memory device, comprising:
a semiconductor body having a main surface;
a memory cell array arranged at the main surface of the semiconductor body, the memory cell array comprising wordline stacks having a first dimension in a direction perpendicular to the main surface of the semiconductor body;
a peripheral area at the main surface of the semiconductor body provided for integrated CMOS circuitry to address the memory cell array in write, read, or erase operations; and
CMOS devices forming CMOS circuitry arranged in the peripheral area, the CMOS devices comprising gate stacks having a second dimension in the direction perpendicular to the main surface of the semiconductor body, wherein the first dimension is smaller than the second dimension, and wherein a difference between the first dimension and the second dimension is compensated by at least one further layer of dielectric material covering the wordline stacks.
2. The integrated memory device of claim 1 , wherein:
the first dimension of the wordline stacks is at most 200 nm; and
the second dimension of the gate stacks is at least 250 nm.
3. The integrated memory device of claim 1 , a pitch of the wordline stacks, measured across the wordline stacks as a distance between corresponding spots of adjacent wordline stacks, is at most 250 nm.
4. The integrated memory device of claim 1 , further comprising at least one layer of dielectric material covering the wordline stacks, the at least one layer of dielectric material having a thickness equal to the difference between the first dimension of the wordline stacks and the second dimension of the gate stacks.
5. The integrated memory device of claim 1 , wherein each wordline stack comprises:
a gate dielectric over a surface of the semiconductor body; and
a conducting layer over the gate dielectric.
6. The integrated memory device of claim 5 , wherein each wordline stack further comprises a hardmask layer over the conducting layer.
7. The integrated memory device of claim 6 , further comprising shallow trench isolations at the main surface of the semiconductor body, the shallow trench isolations providing electrically insulating strips spaced apart and arranged parallel to one another in a region provided for the memory cell array.
8. The integrated memory device of claim 7 , wherein the wordline stacks are spaced apart and arranged parallel to one another and run across the shallow trench isolations in the region provided for the memory cell array, thereby delimiting a location of a memory layer between the gate electrode layer and a channel region of the memory cells.
9. The integrated memory device of claim 5 , wherein the gate dielectric comprises a gate oxide.
10. The integrated memory device of claim 5 , wherein the conducting layer comprises a wordline layer overlying a gate electrode layer.
11. The integrated memory device of claim 1 , wherein the first dimension of the wordline stacks is at most 200 nm.
12. The integrated memory device of claim 1 , wherein the second dimension of the gate stacks is at least 250 nm.
13. The integrated memory device of claim 1 , wherein the memory cell array comprises a plurality of charge trapping memory cells.
14. The integrated memory device of claim 13 , wherein each charge trapping memory cell includes a memory layer, the memory layer comprising a oxide-nitride-oxide layer sequence.
15. The integrated memory device of claim 14 , wherein, for each memory cell, the memory layer is located in an undercut opening between a gate electrode and the semiconductor body.
16. A semiconductor memory device comprising:
a plurality of wordline stacks over a main surface of a semiconductor body, each wordline stack including at least one conductive material and a hardmask overlying the conductive material, the wordline stacks having a first dimension in a direction perpendicular to the main surface;
source/drain regions in the semiconductor body between the wordline stacks;
a gap filling between the wordline stacks extending to an upper surface level of the hardmask;
contact holes disposed in recesses within the gap filling, the contact holes being filled with electrically conductive material that is electrically isolated from the conductive material of the wordline stacks; and
CMOS circuitry disposed in peripheral area of the semiconductor body, the CMOS circuitry including CMOS devices that include gate stacks having a second dimension in the direction perpendicular to the main surface, wherein the first dimension is smaller than the second dimension, and wherein a difference between the first dimension and the second dimension is compensated by at least one further layer of dielectric material covering the wordline stacks.
17. The integrated memory device of claim 16 , wherein:
the first dimension of the wordline stacks is at most 200 nm; and
the second dimension of the gate stacks is at least 250 nm.
18. The integrated memory device of claim 16 , wherein a pitch of the wordline stacks, measured across the wordline stacks at a distance between corresponding spots of adjacent wordline stacks, is at most 250 nm.
19. The integrated memory device of claim 16 , wherein the wordline stacks are each coupled to a plurality of charge trapping memory cells and wherein the CMOS circuitry comprises circuitry to address the memory cells in write, read or erase operations.