Diffusion-Region Stress Sensor IC for Accurate On-Chip Measurement
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Solution Overview
Problem
Integrating resistors within a semiconductor package to sense stress presents challenges due to issues with accuracy and size, particularly related to metal interconnects causing inaccuracies and increased footprint.
Innovation Solution
A stress sensor integrated circuit (IC) using piezoresistive effect with diffusion regions in a semiconductor substrate, minimizing metal interconnects to improve accuracy and reduce size, and incorporating readout circuitry on a single substrate for stress measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metal interconnects are used to integrate resistors within a semiconductor package, then the resistors can be connected and read out, but measurement precision deteriorates due to temperature sensitivity and mechanical interference from the metal interconnects
Solution Approach 1:
The patent removes metal interconnects from the sensor structure entirely, extracting the harmful element that caused temperature sensitivity and mechanical interference. The resistors are connected through diffusion regions only, eliminating the source of measurement errors while maintaining electrical connectivity.
Solution Approach 2:
The patent uses uniform diffusion regions made of the same semiconductor material for both resistor integration and interconnection. This homogeneity ensures that all components experience identical thermal and mechanical conditions, eliminating differential effects that would cause measurement errors.
2Area of stationary object
If metal interconnects are used to connect diffusion regions, then electrical connectivity is achieved, but the sensor footprint increases due to the space required for metal interconnect layouts
Solution Approach 1:
The patent merges the functions of diffusion regions and interconnects into a single integrated structure. The diffusion regions serve dual purposes as both the sensing element and the electrical connection path, eliminating the need for separate metal interconnect layers and reducing overall sensor area.
Solution Approach 2:
The patent extracts metal interconnects from the sensor structure, removing the space-consuming metal layers and their associated routing complexity. This leaves only the essential diffusion regions, significantly reducing the sensor footprint while simplifying the manufacturing process.
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
Enhances stress measurement accuracy by reducing temperature sensitivity and mechanical interference, while minimizing sensor size and increasing density through tighter packing of diffusion regions.
Implementation Method 1
A stress sensor integrated circuit (IC) using piezoresistive effect with diffusion regions in a semiconductor substrate
Data Source
AI summary
An apparatus is described which includes a semiconductor substrate and a shear stress sensor including first diffusion regions in the semiconductor substrate, in which the first diffusion regions are symmetrical over a first axis and a second axis. The first and second axes being orthogonal to each other. The apparatus further comprises normal stress sensors including a second diffusion region in the semiconductor substrate.