Uniform electrochemical plating of metal onto arrays of pillars having different lateral densities and related technology

An apparatus, comprising:

• a first semiconductor die having a first region and a second region non-overlapping with the first region;
• a second semiconductor die spaced apart from the first semiconductor die;
• a plurality of first pillars extending from the first region of the first semiconductor die toward the second semiconductor die and electrically coupling the first and second semiconductor dies;
• and
• a plurality of second pillars extending from the second region of the first semiconductor die toward the second semiconductor die, wherein the plurality of second pillars are electrically isolated from one or both of the first semiconductor die or the second semiconductor die, and wherein an average width of the plurality of first pillars is different than an average width of the plurality of second pillars.

An apparatus, comprising:

• a first semiconductor die having a first region and a second region discrete from the first region;
• a second semiconductor die spaced apart from the first semiconductor die;
• a plurality of first pillars extending from the first region of the first semiconductor die toward the second semiconductor die;
• and
• a plurality of second pillars, wherein a minimum lateral spacing between the plurality of first pillars is different than a minimum lateral spacing between the plurality of second pillars, or an average height of the plurality of second pillars is less than an average height of the plurality of first pillars.