ORO and ORPRO with bit line trench to suppress transport program disturb
View Patent ↗Memory devices having improved TPD characteristics and methods of making the memory devices are provided. The memory devices contain two or more memory cells on a semiconductor substrate and bit line openings containing a bit line dielectric between the memory cells. The memory cell contains a charge storage layer and a first poly gate. The bit line opening extends into the semiconductor substrate. By containing the bit line dielectric in the bit line openings that extend into the semiconductor substrate, the memory device can improve the electrical isolation between memory cells, thereby preventing and/or mitigating TPD.
1. A method of making a memory device comprising sequentially performing the acts of:
providing memory cells and first openings therebetween on a semiconductor substrate;
forming bit line trenches under the first openings in the semiconductor substrate, thereby forming bit line openings;
forming pocket implant regions in the semiconductor substrate adjacent the memory cells;
forming first bit lines in the semiconductor substrate under the bit line openings;
forming spacers adjacent the side surfaces of the memory cells and the bit line trenches;
forming second bit lines under the bit line opening in the semiconductor substrate through the bit line opening, the second bit lines having a narrower width then the first bit lines;
removing the spacers; and
forming bit line dielectrics in the bit line openings and the first openings.
2. The method of claim 1 further comprising:
forming a word line over the semiconductor substrate connecting the memory cells.
3. The method of claim 1 , wherein a memory cell comprises one or more storage nodes and a first poly layer.
4. The method of claim 3 , wherein the upper surface of the first poly layer is higher than the resultant upper surface of the bit line dielectric.
5. The method of claim 1 wherein the spacer comprises organic polymers.
6. The method of claim 1 wherein the spacer comprises at least one selected from the group consisting of polyimides, fluorinated polyimides, polysilsequioxanes such as hydrogen polysilsequioxanes, methyl polysilsequioxanes, butyl polysilsequioxanes, and phenyl polysilsequioxanes, benzocyclobutenes (BCB), fluorinated benzocyclobutene, polyphenylene, polysilazanes, polyphenylquinoxaline, copolymers of 2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole, perfluoroalkoxy resin, fluorinated ethylene propylene, fluoromethacrylate, poly(arylene ether), fuorinated poly(arylene ether), fluorinated parylenes, poly(p-xylxylenes), fluorinated poly(p-xylxylenes), parylene F, parylene N, parylene C, parylene D, amorphous polytetrafluoroethylene, polyquinoline, polyphenylquinoxalines, and polymeric photoresist materials.
7. The method of claim 1 wherein forming the spacers and removing the spacers are performed within a single apparatus.
8. The method of claim 3 , wherein the angle between the side surface of the at least one storage node and the surface of the semiconductor substrate is greater than 90 degrees.
9. The method of claim 3 , wherein at least one of the one or more storage nodes comprises an ORO layer or an ORPRO layer.