End-to-End Analysis of Integration for Thermocouple-Based Sensors Into 3-D ICs

Abstract

Solutions to the integration challenges of a new thermal sensor technology into 3-D integrated circuits (ICs) will be discussed in this paper. Our proposed architecture uses bimetallic thin-film thermocouples, which are thermally linked to points of measurement throughout the 3-D stack with dedicated vias. These vias will be similar to thermal through-silicon vias (TSVs) in structure, yet different in functionality. We propose a low-overhead design methodology by linking the sensor placement task with the existing thermal TSV planning phase for 3-D ICs. A fraction of thermal TSV resources is decoupled from their original use and repurposed for the temperature sensing infrastructure. Tradeoffs concerning the reduction of the thermal TSV resources are investigated. Furthermore, we present an end-to-end system, including the physical realization of the sensor network as well as its analog interface circuitry with the sensor data sampling unit. We demonstrate the operation and correctness of this interface with transistor-level simulations. Next, through thermal modeling and simulation using a state-of-the-art tool (FloTHERM), we demonstrate that we can achieve high accuracy (1 °C error) in temperature tracking while still maintaining the effectiveness of the thermal TSVs in heat management (conforming to a peak temperature constraint of 95 °C).