Staircase formation in a memory array
Methods, systems, and devices for staircase formation in a memory array are described. A first liner material may be deposited on a tread above a first contact surface and a portion of the first liner material may be doped. A second liner material may be deposited over the first liner and a portion of the second liner material may be doped. After doping the portions of the liner materials, the undoped portions of the liner materials may be removed so that the materials above a second contact surface can be at least partially removed via a first removal process. The doped portion of the first liner material may then be cut back so that a second removal process can expose the second contact surface and a third contact (while the first contact surface is protected from the removal process by the liner materials).
1. A method, comprising:
depositing a first liner material within a cavity of a set of stacked materials comprising alternating dielectric material and sacrificial material;
depositing a second liner material within the cavity to at least partially overlay the first liner material;
removing some of the second liner material and leaving a doped portion of the second liner material that overlays a doped portion of the first liner material;
removing some of the first liner material and leaving the doped portion of the first liner material that overlays a first contact surface of a first sacrificial layer of the sacrificial material;
exposing a second contact surface of a second sacrificial layer of the sacrificial material that is below the first sacrificial layer;
exposing a third contact surface of a third sacrificial layer of the sacrificial material that is below the second sacrificial layer;
replacing the sacrificial material with metal material; and
forming a first conductive pillar above a first contact surface of a first metal layer that replaced the first sacrificial layer, a second conductive pillar above a second contact surface of a second metal layer that replaced the second sacrificial layer, and a third conductive pillar above a third contact surface of a third metal layer that replaced the third sacrificial layer.
2. The method of claim 1 , wherein the first conductive pillar is at least partially formed within the doped portion of the first liner material and the doped portion of the second liner material.
3. The method of claim 1 , further comprising:
doping the portion of the first liner material after depositing the first liner material and before depositing the second liner material.
4. The method of claim 1 , further comprising: doping the portion of the second liner material after depositing the second liner material and before removing some of the second liner material.
5. The method of claim 1 , further comprising:
removing a sub-portion of the doped portion of the first liner material to expose some of the first sacrificial layer, wherein the second contact surface of the second sacrificial layer is exposed based at least in part on removing the sub-portion.
6. The method of claim 1 , further comprising:
depositing, after removing some of the second liner material and some of the first liner material, a dielectric film to at least partially overlay the doped portion of the first liner material and the doped portion of the second liner material, the dielectric film to protect a portion of the set of stacked materials as part of exposing the sacrificial material of the set of stacked materials.
7. The method of claim 6 , further comprising:
removing some of the dielectric film and leaving a portion of the dielectric film between the doped portion of the first liner material, the doped portion of the second liner material, and a sidewall of the cavity.
8. The method of claim 7 , further comprising:
removing the portion of the dielectric film before exposing the second contact surface.
9. The method of claim 7 , further comprising:
removing some of the portion of the dielectric film and leaving a remainder of the portion of the dielectric film before exposing the second contact surface; and
removing the remainder of the portion of the dielectric film after exposing the second contact surface.
10. The method of claim 1 , further comprising:
depositing oxide material within the cavity after exposing the third contact surface of the third sacrificial layer, wherein the sacrificial material is replaced with the metal material after depositing the oxide material; and
forming elongated cavities through the oxide material, wherein the first conductive pillar, the second conductive pillar, and the third conductive pillar are each formed within a respective elongated cavity of the elongated cavities.