Multi-Layer Metal Nitride Resistor Structure for Tight 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 precision, such as high-voltage and high-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 tighter TCR tolerance by optimizing the thickness and nitrogen content of these layers, resulting in a TCR variation of less than or equal to ±10 ppm/°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional single-layered or dual-layered resistive structures are used, then the manufacturing process is simple, but the temperature coefficient of resistance (TCR) tolerance is too high for 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 has specific thickness parameters (e.g., first metal nitride layer: 50-200 nm, second metal nitride layer: 200-500 nm) that can be independently controlled to achieve precise TCR tolerance (±10 ppm/°C or better) while maintaining manufacturing feasibility through standardized multi-layer deposition processes
Solution Approach 2:
The patent uses composite material structure combining different metal nitride materials (e.g., tantalum nitride, titanium nitride) with distinct electrical and thermal properties. The intermediate metal layer (e.g., tantalum, titanium) provides different characteristics than the metal nitride layers, creating a composite structure where each material contributes specific properties to achieve the desired TCR performance that cannot be obtained with single-material structures
2Manufacturing precision
If multi-layered resistive structure with optimized thickness and nitrogen content is used, then TCR tolerance is tightened to ±10 ppm/°C, but the manufacturing process becomes more complex
Solution Approach 1:
The patent specifies precise parameter ranges for each layer to achieve the desired TCR tolerance. The first metal nitride layer thickness is controlled at 50-200 nm, the second metal nitride layer at 200-500 nm, and the intermediate metal layer at 50-200 nm. Nitrogen content in the metal nitride layers is optimized at 20-50 atomic percent. These parameter specifications provide clear manufacturing targets that balance precision requirements with process control capability
Solution Approach 2:
Different regions of the resistive structure have different material compositions and thicknesses tailored to specific functional requirements. The first metal nitride layer has different properties than the second metal nitride layer, with each layer optimized for its specific position in the stack. This local optimization allows precise control of TCR characteristics while maintaining overall structure integrity and manufacturability
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.