Method for forming a nonvolatile memory cell comprising a reduced height vertical diode
View Patent ↗A method for forming a nonvolatile memory cell is provided that includes: (1) forming a rail-shaped first conductor above a substrate, (2) forming a rail-shaped second conductor above the first conductor, and (3) forming a substantially vertical first pillar disposed between the first conductor and the second conductor. The first pillar includes a vertically oriented p-i-n diode, and the p-i-n diode includes: (a) a bottom heavily doped region having a first conductivity type, (b) a middle intrinsic or lightly doped region, and (c) a top heavily doped region having a second conductivity type opposite the first conductivity type. The bottom heavily doped region is doped by implantation of arsenic ions and the top heavily doped region is doped by implantation of BF 2 ions. Numerous additional aspects are provided.
1. A method for forming a nonvolatile memory cell, the method comprising:
forming a rail-shaped first conductor above a substrate;
forming a rail-shaped second conductor above the first conductor; and
forming a substantially vertical first pillar disposed between the first conductor and the second conductor,
wherein the first pillar comprises a vertically oriented p-i-n diode, and the p-i-n diode comprises:
a) a bottom heavily doped region having a first conductivity type,
b) a middle intrinsic or lightly doped region, and
c) a top heavily doped region having a second conductivity type opposite the first conductivity type,
wherein the bottom heavily doped region is doped by implantation of arsenic ions and the top heavily doped region is doped by implantation of BF 2 ions.
2. The method of claim 1 , further comprising forming a dielectric layer between the first diode and the second conductor.
3. The method of claim 2 , wherein the dielectric layer comprises an oxide, nitride, or oxynitride.
4. The method of claim 2 , wherein the dielectric layer is silicon dioxide.
5. The method of claim 1 , wherein the nonvolatile memory cell resides in a monolithic three dimensional memory array.
6. A method for forming a monolithic three dimensional memory array, the method comprising:
forming a plurality of substantially parallel, substantially coplanar rail-shaped first conductors above a substrate;
forming a plurality of substantially parallel, substantially coplanar rail-shaped second conductors above the first conductors; and
forming a plurality of substantially vertical first pillars;
wherein each first pillar is disposed between one of the first conductors and one of the second conductors;
wherein each of the first pillars comprises a vertically oriented p-i-n diode; and
wherein each p-i-n diode comprises:
a) a bottom heavily doped region having a first conductivity type;
b) a middle intrinsic or lightly doped region; and
c) a top heavily doped region having a second conductivity type opposite the first conductivity type;
wherein the bottom heavily doped region is doped by implantation of arsenic ions and the top heavily doped region is doped by implantation of BF 2 ions.
7. The method of claim 6 , further comprising forming:
forming a plurality of substantially vertical second pillars above the first pillars; and
forming a plurality of substantially parallel, substantially coplanar rail-shaped third conductors above the second conductors.
8. The method of claim 7 , wherein each of the second pillars is disposed between one of the second conductors and one of the third conductors.
9. The method of claim 7 , further comprising forming a plurality of substantially parallel, substantially coplanar rail-shaped fourth conductors above the third conductors, wherein each of the second pillars is disposed between one of the third conductors and one of the fourth conductors.