Multi-Layer IC Resistor Stack for Low-Drift TCR Control
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Solution Overview
Problem
Traditional thin film resistors (TFRs) with single-layered or dual-layered resistive structures have temperature coefficient of resistance (TCR) tolerances that are too high for applications requiring high precision, such as high-voltage devices and precision measuring instruments, limiting their suitability.
Innovation Solution
An integrated chip (IC) with a resistor featuring a multi-layered resistive structure comprising a first metal nitride structure, a metal structure, and a second metal nitride structure, which provides a tight TCR tolerance of ≤±10 ppm/°C, suitable for high-precision applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional single-layered or dual-layered resistive structures are used, then manufacturing complexity is reduced, but TCR tolerance becomes too high for high-precision applications
Solution Approach 1:
The resistive structure is divided into multiple layers (first metal nitride layer, second metal nitride layer, and intermediate metal layer) instead of using a single layer. Each layer contributes to achieving the target TCR tolerance, with the intermediate metal layer having a different TCR than the outer metal nitride layers, allowing precise control of the overall TCR through thickness ratio optimization.
Solution Approach 2:
The patent uses a composite structure combining different metal materials (first metal nitride, second metal nitride, and intermediate metal) with different TCR characteristics. By stacking these materials with specific thickness ratios, the composite structure achieves a TCR tolerance that cannot be obtained with single-layer or dual-layer structures alone.
2Manufacturing precision
If multi-layered resistive structure is implemented, then TCR tolerance is improved to ≤±10 ppm/°C, but manufacturing process complexity increases
Solution Approach 1:
The patent controls the TCR tolerance by adjusting the thickness parameters of each layer. Specifically, the thickness ratio between the intermediate metal layer and the outer metal nitride layers is optimized to achieve the desired TCR tolerance of ≤±10 ppm/°C, transforming a material property control problem into a geometric parameter control problem that is more manageable during manufacturing.
3Measurement precision
If tighter TCR tolerance is achieved through multi-layered structure, then measurement precision in high-precision applications is improved, but device complexity increases
Solution Approach 1:
Different layers in the resistive structure have different local properties (TCR values). The intermediate metal layer has a different TCR than the outer metal nitride layers, allowing each layer to contribute differently to the overall resistance and temperature coefficient, enabling precise TCR control for high-precision measurement applications.
Data Source
AI summary
Various embodiments of the present disclosure are directed towards an integrated chip (IC). The IC comprises a substrate. A resistor overlies the substrate. The resistor comprises a first metal nitride structure, a second metal nitride structure spaced from the first metal nitride structure, and a metal structure disposed between the first metal nitride structure and the second metal nitride structure. A first dielectric structure is disposed over the substrate and the resistor.