High-aspect ratio through-silicon vias for the integration of microfluidic cooling with 3D microsystems

• We propose a 3D system with TSVs embedded within a microfluidic heat sink.
• We present the fabrication of high-aspect ratio TSVs using two silicon etch masks.
• Void-free TSVs are characterized using X-ray inspection and resistance measurement.

Microfluidic cooling technology is a promising thermal solution for high-performance three-dimensional integrated circuits (3D ICs). However, the integration of microfluidic cooling into 3D ICs inevitably impacts tier-to-tier through-silicon vias (TSVs) by increasing their length and diameter (for a fixed aspect ratio). To address this challenge, this paper presents the fabrication of very high-aspect ratio (23:1) TSVs within a microfluidic pin-fin heat sink using two types of silicon etch masks. Void-free TSVs are electrically characterized using X-ray inspection and four-point resistance measurements.

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