Multi-level stack having multi-level contact and method
View Patent ↗A method for forming a multi-level stack having a multi-level contact is provided. The method includes forming a multi-level stack comprising a specified number, n, of conductive layers and at least n−1 insulating layers. A via formation layer is formed over the stack. A first via is etched in the via formation layer at a first edge of the stack. A first multi-level contact is formed in the first via. For a particular embodiment, a second via may be etched in the via formation layer at a second edge of the stack and a second multi-level contact may be formed in the second via.
1. A method comprising:
forming a multi-level stack comprising a specified number, n, of conductive layers and at least n−1 insulating layers, the multi-level stack having a plurality of outside edges;
forming a via formation layer covering the plurality of outside edges of the multi-level stack;
etching a via in the via formation layer at one of the plurality of outside edges along an outside edge of each of the specified number of conductive layers; and
forming a multi-level contact in the via connecting the specified number of conductive layers,
wherein forming the via formation layer comprises:
depositing the via formation layer, and
planarizing the via formation layer.
2. The method of claim 1 , further comprising removing the via formation layer.
3. The method of claim 1 , wherein the specified number of conductive layers are only conductively contacted by a single multi-level contact.
4. The method of claim 1 , wherein:
the conductive layers comprise a lower conductive layer and upper conductive layers, and
the multi-level contact is configured to connect a region of a top surface of the lower conductive layer to edges of the upper conductive layers on the plurality of outside edges of the multi-level stack.
5. The method of claim 1 further comprising:
depositing a photoresist layer over the planarized via formation layer; and
patterning the photoresist layer to expose the via formation layer at the plurality of outside edges of the multi-level stack.
6. The method of claim 5 , further comprising removing the photoresist layer.
7. A method for forming a multi-level stack having a multi-level contact, comprising:
forming a first conductive layer;
forming a first insulating layer over the first conductive layer;
forming a second conductive layer over the first insulating layer without forming contacts in the first insulating layer;
forming a via formation layer over the second conductive layer and outside edges of the multi-level stack;
etching a via into the via formation layer at an outside edge of the first conductive layer and the second conductive layer; and
forming a multi-level contact in the via connecting the first and second conductive layers,
wherein forming the via formation layer comprises:
depositing the via formation layer, and
planarizing the via formation layer.
8. The method of claim 7 , further comprising further comprising removing the via formation layer.
9. The method of claim 7 , wherein the first and second conductive layers are only conductively contacted by a single multi-level contact.
10. The method of claim 7 , wherein the multi-level contact is configured to connect a first region of a top surface of the first conductive layer to an outside edge of the second conductive layer.
11. The method of claim 1 , further comprising:
depositing a photoresist layer over the planarized via formation layer; and
patterning the photoresist layer to expose the via formation layer at the outside edges of the multi-level stack.
12. The method of claim 11 , further comprising removing the photoresist layer.
13. A multi-level stack, comprising:
a specified number, n, of conductive layers;
at least n−1 insulating layers;
a first multi-level contact at a first outside edge of the multi-level stack connecting the specified number of conductive layers, the first multi-level contact disposed on first side surfaces of the conductive layers; and
a second multi-level contact at a second outside edge of the multi-level stack connecting the specified number of conductive layers, the second multi-level contact disposed on second side surfaces of the conductive layers.
14. The multi-level stack of claim 13 , wherein the specified number of conductive layers are only conductively contacted by a single multi-level contact.
15. The multi-level stack of claim 13 , wherein each of the first and second multi-level contacts is configured to connect the conductive layers to each other.
16. The multi-level stack of claim 13 , wherein:
the conductive layers comprise a lower conductive layer and upper conductive layers,
each of the first and second multi-level contacts is configured to connect a region of a top surface of the lower conductive layer to the outside edges of the upper conductive layers of the multi-level stack.
17. The multi-level stack of claim 13 , wherein each of the first and second multi-level contacts is formed over a buffer layer that is deposited over a substrate.
18. The multi-level stack of claim 13 , wherein the insulating layers are formed between the conductive layers, and wherein the insulating layers are formed without providing contacts between the conductive layers.