Isolation Structure for Stacked Dies

Abstract

An isolation structure for stacked dies is provided. A through-silicon via is formed in a semiconductor substrate. A backside of the semiconductor substrate is thinned to expose the through-silicon via. An isolation film is formed over the backside of the semiconductor substrate and the exposed portion of the through-silicon via. The isolation film is thinned to re-expose the through-silicon via, and conductive elements are formed on the through-silicon via. The conductive element may be, for example, a solder ball or a conductive pad. The conductive pad may be formed by depositing a seed layer and an overlying mask layer. The conductive pad is formed on the exposed seed layer. Thereafter, the mask layer and the unused seed layer may be removed.

Description

TECHNICAL FIELD[0001]This invention relates generally to integrated circuits and, more particularly, to an isolation structure for stacked dies.BACKGROUND[0002]Since the invention of the integrated circuit, the semiconductor industry has experienced rapid growth due to continuous improvements in the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.). For the most part, this improvement in integration density has come from repeated reductions in minimum feature size, which allows more components to be integrated into a given area.[0003]These integration improvements are essentially two-dimensional (2D) in nature, in that the volume occupied by the integrated components is essentially on the surface of the semiconductor wafer. Although dramatic improvement in lithography has resulted in considerable improvement in 2D integrated circuit (IC) formation, there are physical limits to the density that can be achieved in two dimensi...

AI Technical Summary

Benefits of technology

[0003]These integration improvements are essentially two-dimensional (2D) in nature, in that the volume occupied by the integrated components is essentially on the surface of the semiconductor wafer. Although dramatic improvement in lithography has resulted in considerable improvement in 2D integrated circuit (IC) formation, there are physical limits to the density that can be achieved in two dimensions. One of these limits is the minimum size needed to make these components. Also, when more devices are put into one chip, more complex designs are required.

Problems solved by technology

Although dramatic improvement in lithography has resulted in considerable improvement in 2D integrated circuit (IC) formation, there are physical limits to the density that can be achieved in two dimensions.

One of these limits is the minimum size needed to make these components.

Also, when more devices are put into one chip, more complex designs are required.

The dielectric processes used on the circuit side of the substrate are not applicable to the backside due to the thinned substrate.

As a result, the backside of the substrate is left unprotected when the solder balls are placed on the exposed TSVs, limiting the wetting surface for the solder ball without forming electrical shorts between the solder ball and the substrate.

Furthermore, the structure limits the mechanical strength with the bonding surface and limits the I / O pin population.

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