Vias with vertically non-uniform or discontinuous stack

A method of forming a backside via, comprising:

• forming an opening in a substrate, wherein the opening has a first portion and a second portion below the first portion;
• filling the second portion of the opening with a sacrificial material;
• forming a lining along sidewalls of the opening in the first portion of the opening above the sacrificial material;
• removing the sacrificial material;
• and
• forming a via in the opening, wherein the via has a first width at the first portion of the opening adjacent to the lining and a second width at the second portion of the opening below the lining, and wherein the via has an uppermost surface at a same level as an uppermost surface of the lining.

A semiconductor device, comprising:

• a substrate;
• a non-planar transistor device with a source and a drain over the substrate;
• a via through the substrate and coupled to one of the source and the drain, wherein the via comprises:
• a first region with a first width, wherein the first region contacts the one of the source and the drain;
• and
• a second region with a second width below the first region, wherein the second width is greater than the first width, wherein the second region has a non-uniform thickness through a length of the second region of the via, and wherein an end of the second region of the via opposite from the first region of the via is rounded;
• and
• a lining on sidewalls of the first region of the via, wherein the via has an uppermost surface at a same level as an uppermost surface of the lining.

An electronic system, comprising:

• a board;
• a package substrate coupled to the board;
• and
• a die coupled to the package substrate, wherein the die comprises:
• a substrate;
• a non-planar transistor device with a source and a drain over the substrate;
• a via through the substrate and coupled to one of the source and the drain, wherein the via comprises:
• a first region with a first width, wherein the first region contacts the one of the source and the drain;
• and
• a second region with a second width below the first region, wherein the second width is greater than the first width, wherein the second region has a non-uniform thickness through a length of the second region of the via, and wherein an end of the second region of the via opposite from the first region of the via is rounded;
• and
• a lining on sidewalls of the first region of the via, wherein the via has an uppermost surface at a same level as an uppermost surface of the lining.