Methods of forming integrated structures comprising vertical channel material and having conductively-doped semiconductor material directly against lower sidewalls of the channel material
Some embodiments include an integrated structure having vertically-stacked conductive levels. Upper conductive levels are memory cell levels, and a lower conductive level is a select device level. Conductively-doped semiconductor material is under the select device level. Channel material extends along the memory cell levels and the select device level, and extends into the conductively-doped semiconductor material. A region of the channel material that extends into the conductively-doped semiconductor material is a lower region of the channel material and has a vertical sidewall. Tunneling material, charge-storage material and charge-blocking material extend along the channel material and are between the channel material and the conductive levels. The tunneling material, charge-storage material and charge-blocking material are not along at least a portion of the vertical sidewall of the lower region of the channel material, and the conductively-doped semiconductor material is directly against such portion. Some embodiments include methods of forming integrated structures.
1. A method of forming an integrated structure, comprising:
forming vertically-stacked levels over a base; the base comprising a sacrificial material over a first conductively-doped semiconductor material; upper levels of the vertically-stacked levels being memory cell levels, and a lower level of the vertically-stacked levels being a select device level;
forming a pair of openings extending through the memory cell levels, through the select device level, through the sacrificial material, and into the first conductively-doped semiconductor material; the openings being a first opening and a second opening;
forming a tunneling material, a charge-storage material and a charge-blocking material extending vertically along sidewalls of the first and second openings to narrow the first and second openings;
forming channel material within the narrowed first and second openings; the channel material extending vertically along the memory cell levels, the select device level and the sacrificial material, and extending downwardly into the conductively-doped semiconductor material; a region of the channel material along the sacrificial material within the narrowed first opening being comprised by a first lower region, and a region of the channel material along the sacrificial material within the narrowed second opening being comprised by a second lower region; the first and second lower regions of the channel material having first and second sidewalls, respectively; the first and second lower regions of the channel material having first segments along the sacrificial material, and having lowest segments beneath the first segments and along the first conductively-doped semiconductor material;
forming a third opening between the first and second openings, the third opening extending through the vertically-stacked levels and into the sacrificial material;
providing etchant within the third opening to remove the sacrificial material, and to remove regions of the tunneling material, charge-storage material, and charge-blocking material along the first segments of the channel material to expose the first and second sidewalls along said first segments, and to form a void over the first conductively-doped semiconductor material; regions of the tunneling material, charge-storage material, and charge-blocking material along the lowest segments not being removed and remaining along the first conductively-doped semiconductor material; and
forming a second conductively-doped semiconductor material within the void and directly against the exposed first and second sidewalls of the channel material; the second conductively-doped semiconductor material being over the regions of the tunneling material, charge-storage material, and charge-blocking material remaining along the first conductively-doped semiconductor material.
2. The method of claim 1 wherein the vertically-stacked levels are initially sacrificial material, and comprising replacing the sacrificial material with a conductive material after forming the third opening.
3. The method of claim 1 wherein the first and second conductively-doped semiconductor materials are a same composition as one another.
4. The method of claim 1 wherein the first and second conductively-doped semiconductor materials are different compositions relative to one another.
5. The method of claim 1 wherein the forming of the second conductively-doped semiconductor material forms the second conductively-doped semiconductor material to line sidewalls of the third opening, and further comprising filling the lined opening with a metal-containing core.
6. The method of claim 1 wherein the sacrificial material comprises germanium; and wherein the first conductively-doped semiconductor material consists of conductively-doped silicon.
7. The method of claim 1 wherein the sacrificial material comprises silicon and germanium; and wherein the first conductively-doped semiconductor material consists of conductively-doped silicon.
8. The method of claim 7 further comprising lining sidewalls of the third opening with a silicon layer prior to providing the etchant within the third opening.