Contact features of semiconductor devices
A method of fabricating a semiconductor device includes recessing an upper portion of a first dielectric layer disposed over a conductive feature. The method includes filling the recessed upper portion with a second dielectric layer to form a void embedded in the second dielectric layer. The method includes etching the second dielectric layer and the first dielectric layer to form a contact opening that exposes at least a portion of the conductive feature using the void to vertically align at least a lower portion of the contact opening with the conductive feature. The method includes filling the contact opening with a conductive material to form a contact feature electrically coupled to the conductive feature.
1. A method, comprising:
forming a first opening in a first dielectric layer over a conductive feature; and
forming a second opening in the first dielectric layer, the second opening vertically extending from the first opening, the second opening exposing the conductive feature, wherein forming the second opening includes:
depositing a second dielectric layer in the first opening, resulting in a void embedded in the second dielectric layer and directly above the conductive feature, and
removing a portion of the first dielectric layer below the second dielectric layer to form the second opening, the second opening being vertically aligned with the void.
2. The method of claim 1 , wherein the first opening is formed to a first width and the second opening is formed to a second width that is less than the first width.
3. The method of claim 2 , wherein:
depositing the second dielectric layer results in the void having the second width, and
removing the portion of the first dielectric layer is facilitated by the void such that the second opening is formed to the second width.
4. The method of claim 1 , wherein depositing the second dielectric layer includes adjusting a rate of depositing to form an overhang of the second dielectric layer, the overhang including a first portion and a second portion laterally extending towards each other to form the void.
5. The method of claim 1 , wherein the first dielectric layer and the second dielectric layer have different etching characteristics.
6. The method of claim 1 , wherein forming the second opening further includes, before removing the portion of the first dielectric layer, removing a center portion of the second dielectric layer surrounding the void, the center portion being vertically aligned with the conductive feature.
7. The method of claim 6 , wherein removing the center portion of the second dielectric layer leaves portions of the second dielectric layer as spacers along sidewalls of the first opening.
8. The method of claim 1 , wherein:
the conductive feature is a first conductive feature, and
the method further comprises depositing a conductive material in the first opening and the second opening, resulting in a second conductive feature electrically coupled to the first conductive feature.
9. A method, comprising:
forming a first opening in a first dielectric layer over a conductive feature; and
forming a second opening in the first dielectric layer, the second opening disposed below the first opening, wherein forming the second opening includes:
filling the first opening with a second dielectric layer, the second dielectric layer having a void embedded therein, the void being vertically aligned with the conductive feature, and
removing portions of the second dielectric layer and the first dielectric layer to form the second opening, wherein:
the second opening exposes the conductive feature, and
the second opening and the void have the same width.
10. The method of claim 9 , wherein filling the first opening includes adjusting a rate of filling such that portions of the second dielectric layer merge toward each other to form the void.
11. The method of claim 9 , further comprising filling the first opening and the second opening with a conductive material to form a contact electrically coupled to the conductive feature.
12. The method of claim 9 , wherein removing the portions of the second dielectric layer and the first dielectric layer includes performing an anisotropic etching process using an etchant.
13. The method of claim 12 , wherein the first dielectric layer and the second dielectric layer exhibit different etching rates during the anisotropic etching process.
14. The method of claim 9 , wherein removing the portions of the second dielectric layer and the first dielectric layer leaves spacers lining sidewalls of the first opening, the spacers including remaining portions of the second dielectric layer.
15. The method of claim 9 , wherein removing the portions of the second dielectric layer and the first dielectric layer is facilitated by the void such that the second opening is vertically aligned with the void.
16. The method of claim 8 , wherein:
the first opening is formed to a first width, and
the second opening is formed to a second width that is less than the first width.
17. A method, comprising:
recessing a first dielectric layer to form a first opening over a first conductive feature;
forming a second dielectric layer in the first opening, the second dielectric layer including a void that is vertically aligned with the first conductive feature;
removing a portion of the second dielectric layer surrounding the void, thereby exposing the first opening;
removing a portion of the first dielectric layer below the second dielectric layer to form a second opening, the second opening vertically aligned with the void; and
forming a second conductive feature in the second opening and the exposed first opening, the second conductive feature electrically coupled to the first conductive feature.
18. The method of claim 17 , wherein the first opening is formed to a first width and the second opening is formed to a second width that is less than the first width.
19. The method of claim 17 , wherein removing the portion of the second dielectric layer and removing the portion of the first dielectric layer is implemented by performing a same anisotropic etching process.
20. The method of claim 17 , wherein removing the portion of the second dielectric layer forms spacers extending along sidewalls of the first opening.