3D chip testing through micro-C4 interface
The embodiments of the present invention relate to semiconductor device manufacturing, and more particularly to structures and methods of directly testing semiconductor wafers having micro-solder connections. According to one embodiment of the present invention, a method of forming a pattern of micro-solder connections coupled with a through substrate via (TSV) that can be directly tested by electrical probing, without the use of a testing interposer, is disclosed. According to another embodiment, a method of testing the pattern of micro-solder connections is disclosed. According to another embodiment, a novel electrical probe tip structure, having contacts on the same pitch as the pattern of micro-solder connections is disclosed.
1. A method for electrically testing an integrated circuit (IC), comprising:
forming a plurality of through substrate vias (TSV) through an entire thickness of the integrated circuit (IC) chip, each TSV electrically connecting a first surface of the IC chip to a second surface on an opposite side of the IC chip, wherein an individual solder connection formed on the second surface of the IC chip connects to a corresponding individual TSV of said plurality via a respective conductor;
forming a respective pattern of micro-solder connections around a respective TSV on the first surface of the IC chip, each said respective pattern of micro-solder connections of the first surface sharing an assigned common power/ground signal grid or input/output signal grid with the corresponding TSV, wherein a center of an individual micro-solder connection in the pattern is separated from a center of another individual micro-solder connection by a distance of approximately 62 μm, and wherein the respective pattern of micro-solder connections allows the IC chip to be electrically tested by directly contacting the micro-solder connections with a single electrical probe tip without the need for a testing interposer,
wherein the single electrical probe tip comprises:
a circular base; and
a raised contact point centered on the circular base, wherein the raised contact point has a circular shape and a width or diameter less than a width or diameter of the circular base.
2. The method of claim 1 , wherein the forming the respective pattern of micro-solder connections around the respective TSV on the surface of the IC chip comprises:
forming a bonding pad on the surface of the IC chip: and
forming a ball of a conductive material on the bonding pad, wherein the ball has a substantially spherical shape.
3. The method of claim 1 , wherein the forming the respective pattern of micro-solder connections around the respective TSV on the surface of the IC chip comprises:
forming a center micro-solder connection centered on the TSV; and
forming six (6) micro-solder connections on the first surface around the TSV in a hexagonal pattern.
4. The method of claim 1 , wherein the forming the respective pattern of micro-solder connections around the respective TSV on the surface of the IC chip comprises:
forming eight (8) micro-solder connections on the first surface surrounding the TSV, wherein three (3) micro-solder connections are formed above the TSV, one (1) μ- micro-solder connection is formed adjacent to a left side of the TSV, one (1) micro-solder connection is formed adjacent to a right side of the TSV, and three (3) micro-solder connections are formed below the TSV.
5. The method of claim 1 , wherein the respective pattern of micro-solder connections has an overall length of approximately 185 μm and an overall width of approximately 161 μm.
6. The method of claim 1 , wherein the respective pattern of micro-solder connections is electrically connected to a single power/ground signal domain.
7. The method of claim 1 , wherein the respective pattern of micro-solder connections is electrically connected to a single IO signal domain.