BEOL Metal Resistor Thermal Sensing for Dense IC Layouts
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Solution Overview
Problem
The incorporation of deep wells for thermal sensors in advanced semiconductor processes becomes challenging as transistors progress to smaller geometries, making bipolar junction transistors (BJTs) less feasible, necessitating a new type of thermal sensor compatible with high device packing density and IC manufacturing processes.
Innovation Solution
A thermal sensor is fabricated during back-end-of-line (BEOL) processes using metal lines instead of BJTs, integrated into the semiconductor structure with conductive structures embedded in dielectric layers, and isolated by dummy regions to maintain pattern density and electrical/thermal isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If deep wells are used for thermal sensors in traditional semiconductor processes, then thermal sensing capability is achieved, but device packing density decreases and manufacturing complexity increases
Solution Approach 1:
The patent transitions thermal sensing from the front-end deep well structure to the back-end metal interconnect layer, effectively moving the sensing element to a different dimensional plane in the semiconductor stack. This allows thermal sensing without occupying front-end device area, thereby maintaining high device packing density while achieving accurate thermal measurement through the metal layer's temperature-dependent resistance.
2Measurement precision
If deep wells are used for thermal sensors, then thermal sensing is enabled, but manufacturing process complexity increases
Solution Approach 1:
The patent merges the thermal sensing function with the existing metal interconnect layer that is already part of the standard back-end-of-line manufacturing process. By forming the thermal sensor as a metal trace within the interconnect structure, the sensing element is integrated into an existing manufacturing step rather than requiring separate deep well formation processes, thereby reducing overall manufacturing complexity.
Solution Approach 2:
The metal interconnect layer serves dual purposes: it provides electrical interconnection functionality and simultaneously acts as the thermal sensing element. The metal trace's inherent temperature-dependent resistance property allows it to self-function as a thermal sensor without requiring additional specialized structures or processes, enabling the system to serve itself for both interconnection and thermal monitoring.
3Area of stationary object
If metal lines are used for thermal sensing instead of BJTs, then chip footprint is reduced and manufacturing is simplified, but thermal sensing accuracy must be maintained
Solution Approach 1:
The patent utilizes the temperature-dependent resistance parameter of the metal interconnect layer as the basis for thermal sensing. By measuring changes in the metal trace's resistance with temperature, the system achieves accurate temperature measurement. The metal's well-characterized resistive response to temperature changes enables precise thermal sensing while maintaining a compact footprint, as the sensing element is simply an existing interconnect trace rather than a bulky BJT structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The metal line-based thermal sensor provides robust temperature measurement capabilities, maintaining accuracy and reducing chip footprint and costs, while being compatible with complex ICs.
Implementation Method 1
A thermal sensor is fabricated during back-end-of-line (BEOL) processes using metal lines
Data Source
AI summary
A semiconductor structure includes a substrate, a dielectric structure over the substrate, a conductive structure configured for temperature measurement and embedded in the dielectric structure, a passivation layer over the dielectric structure, and conductive pads over the passivation layer and electrically connected to the conductive structure. The conductive structure includes conductive lines, and conductive bars and vias electrically connecting the conductive lines.