Substrate and method including forming a via comprising a conductive liner layer and conductive plug having different microstructures
In an embodiment, a substrate includes semiconductor material and a conductive via. The conductive via includes a via in the substrate, a conductive plug filling a first portion of the via and a conductive liner layer that lines side walls of a second portion of the via and is electrically coupled to the conductive plug. The conductive liner layer and the conductive plug have different microstructures.
1. A method, comprising:
forming a first conductive layer in a first portion of an opening in a semiconductor substrate using first deposition parameters such that the first conductive layer fills the opening in the first portion; and
forming a second conductive layer on the first conductive layer in a second portion of the opening using second deposition parameters such that the second conductive layer bounds a first gap in the second portion,
wherein the first deposition parameters are selected to favour growth of the first conductive layer in a vertical direction with respect to a major surface of the semiconductor substrate and suppress growth in lateral directions and on a front surface of the semiconductor substrate,
wherein the second deposition parameters are selected to favour conformal growth of the second conductive layer in a lateral direction with respect to the major surface of the semiconductor substrate,
wherein the first conductive layer and the second conductive layer are formed by electroplating.
2. The method of claim 1 , further comprising forming the second conductive layer on a first surface of the semiconductor substrate surrounding the opening.
3. The method of claim 1 , wherein the first conductive layer is applied to abase of a blind via and the base of the blind via is filled with the first conductive layer.
4. The method of claim 3 , wherein the blind via is filled to a depth of 10% to 70% of a total depth of the blind via.
5. The method of claim 3 , further comprising:
working a second surface of the semiconductor substrate; and
exposing a portion of the first conductive layer in the second surface of the substrate.
6. The method of claim 1 , further comprising:
forming a first insulating layer over the second conductive layer that surrounds a second gap; and
forming a second insulating layer over the second gap so as to form an enclosed cavity within the opening.
7. The method of claim 1 , wherein the first deposition parameters and the second deposition parameters are selected such that the first conductive layer forms a conductive plug with a height h 1 and the second conductive layer has a thickness t whereby h 1 ≧3t.
8. The method of claim 7 , wherein 0.5 μm≦t≦3 μm and wherein 5 μm≦h 1 ≦70 μm.
9. The method of claim 1 , wherein a different electroplating chemistry is used for the deposition of the first conductive layer and the second conductive layer.
10. The method of claim 1 , wherein the first conductive layer is in direct contact with the second conductive layer.