Early Bit Line Air Gap Formation
AssigneeSanDisk Technologies LLC
InventorsHiroto Ohori, Takuya Futase, Yuji Takahashi, Toshiyuki Sega, Kiyokazu Shishido, Kotaro Jinnouchi, Noritaka Fukuo
Life of this patent
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Abstract
Dummy bit lines of are formed in a sacrificial layer at locations where bit lines are to be formed, with bit lines separated by trenches that extend through the sacrificial layer. Enclosed air gap structures are formed in the trenches between the dummy bit lines. Subsequently, the dummy bit lines are replaced with metal to form bit lines.
Claims28
A method of forming air gap structures between conductive lines, the method comprising:
- forming a first layer;
- forming a second layer on the first layer;
- patterning the second layer using a selective etch that provides an etch rate of the second layer that is substantially higher than an etch rate of the first layer thereby forming a first trench in the second layer at a location where an air gap between conductive lines is to be formed;
- depositing a third layer in the first trench the third layer encapsulating an air gap in the first trench;
- removing the patterned second layer to form a second trench while the air gap remains in place;
- depositing a bather layer and conductive line metal in the second trench;
- and
- performing Chemical Mechanical Polishing (CMP) to remove excess conductive line material while leaving conductive line material in the second trench to form a conductive line.
A method of forming bit lines of a nonvolatile memory comprising:
- forming a plurality of dummy bit lines in a sacrificial layer of sacrificial material at locations where a plurality of bit lines are to be formed, the plurality of dummy bit lines separated by a plurality of trenches that extend through the sacrificial layer;
- subsequently forming a plurality of enclosed air gap structures in the plurality of trenches;
- and
- subsequently replacing the plurality of dummy bit lines with metal to form the plurality of bit lines.
A method of forming bit lines of a nonvolatile memory comprising:
- forming a first sacrificial layer of a first sacrificial material;
- patterning the first sacrificial layer of the first sacrificial material to form a first plurality of trenches at locations where bit lines are to be formed;
- subsequently depositing a second sacrificial material in the first plurality of trenches and over the patterned first layer of the first sacrificial material;
- subsequently planarizing the second sacrificial layer to expose portions of the first sacrificial layer;
- selectively removing the first sacrificial material to leave portions of the second sacrificial material as dummy bit lines at locations where bit lines are to be formed;
- subsequently forming a plurality of enclosed air gap structures between dummy bit lines;
- and
- subsequently replacing dummy bit lines with metal to form the bit lines.
Dependencies are inferred from the claim text.