Electroless metal through silicon via
A method of making a substrate-through metal via having a high aspect ratio, in a semiconductor substrate, and a metal pattern on the substrate surface, includes providing a semiconductor substrate (wafer) and depositing poly-silicon on the substrate. The poly-silicon on the substrate surface is patterned by etching away unwanted portions. Then, Ni is selectively deposited on the poly-silicon by an electroless process. A via hole is made through the substrate, wherein the walls in the hole is subjected to the same processing as above. Cu is deposited on the Ni by a plating process. Line widths and spacings <10 μm are provided on both sides of the wafer.
1. A semiconductor device comprising:
a substrate wafer of silicon;
on oxide layer on the substrate;
lateral redistribution/routing structures on the wafer surface;
poly-silicon layers on the field and on the walls of the vias, respectively, a gap being present between said poly-silicon layers;
a continuous Cu layer covering the lateral redistribution/routing structures and the surfaces in the via hole;
a continuous barrier layer of Ni on which the Cu layer is provided, said barrier layer of Ni bridging the gap between the poly-silicon on the walls in the via and poly-silicon on the field, respectively, to provide a continuous conductive layer on which the Cu layer is provided.
2. The device according claim 1 , wherein the oxide is thermally grown and a thickness of the oxide layer between the silicon substrate and the Cu layer is >0.5 μm.
3. The device according to claim 1 wherein the oxide has a breakdown voltage of above 500 V.
4. The device according to claim 1 , wherein the vias are hermetically sealed.
5. The device according to claim 1 , wherein a line width of the routing structures is <10 μm.
6. The device according to claim 1 , wherein a line width of the routing structures is <5 μm.