Methods of forming a TSV wafer with improved fracture strength

A method comprising:

• forming an array of through-substrate vias through a thickness of a single crystal silicon substrate and forming semiconductor devices on a front side of the single crystal silicon substrate, the through-substrate vias extending vertically from the front side of the substrate to a back side of the substrate;
• removing a first portion of the substrate to form an opening that extends a predetermined depth into the back side of the substrate and that defines a second portion of the substrate, the second portion containing the array and remaining in direct contact with and laterally surrounding vertical sidewalls of the through-substrate vias;
• filling the opening with an alternate material to improve a durability of the single crystal silicon substrate and reduce a potential for cracking during fabrication, the alternate material having a lower modulus of elasticity than the single crystal silicon substrate;
• and
• polishing the back side of the substrate so that an exposed surface of the alternate material is essentially co-planar with the back side of the substrate.

A method comprising:

• forming through-substrate vias through a thickness of a substrate and forming semiconductor devices on a front side of the substrate, the thickness of the substrate being measured from the front side of the substrate to a back side of the substrate;
• removing a first portion of the substrate to form an opening that extends a predetermined depth into the back side of the substrate and that defines a second portion of the substrate,
• the second portion remaining in direct contact with and laterally surrounding a vertical sidewall of one of the through-substrate vias such that the vertical sidewall is physically separated from the opening by a distance that is at least equal to a width of the through-substrate via, and
• the predetermined depth being approximately one-half the thickness of the substrate;
• filling the opening with an alternate material having a lower modulus of elasticity than the substrate such that the alternate material extends laterally between adjacent second portions that laterally surround adjacent through-substrate vias, the alternate material being at least as thermally conductive as the substrate;
• and
• polishing the back side of the substrate so that an exposed surface of the alternate material is essentially co-planar with the back side of the substrate.