Thin-Film Resistor Two-Layer Structure High Resistance TCR
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Solution Overview
Problem
Conventional thin-film resistors face challenges in achieving high resistance values while maintaining excellent temperature coefficient of resistance (TCR) characteristics, particularly when increasing specific resistance, as the characteristics of silicon nitride become dominant, making it difficult to set TCR to approximately zero.
Innovation Solution
A thin-film resistor is designed with a two-layer structure, where one layer has a positive TCR and the other has a negative TCR, each containing Si, Cr, and N, with varying percentages of silicon nitride to achieve high resistance values and stable TCR characteristics, and optionally includes additional metal elements like Ti, Zr, or Al to adjust the resistive film characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of a film of resistive material is reduced to decrease chip size, then the chip size is reduced, but the long-term reliability and characteristics of the thin-film resistor deteriorate
Solution Approach 1:
The patent changes the material parameter (specific resistance) by adding valve metals or transition metals to the chromium-silicon base material, enabling the film to achieve higher resistivity without reducing thickness, thus maintaining reliability while allowing chip size reduction
Solution Approach 2:
The patent creates composite resistive materials by combining chromium, silicon, and additional valve metals or transition metals (such as Nb, Ta, Al, Cu, Mn, Zr, or Ni), forming a multi-component system that achieves both high specific resistance and improved reliability
2Quantity of substance
If the specific resistance of the resistive material is increased to maintain resistance values with reduced chip size, then the resistance value is maintained, but the TCR characteristics deteriorate as silicon nitride characteristics become dominant
Solution Approach 1:
The patent optimizes the compositional parameters by controlling the ratios of chromium, silicon, and added metals, along with sputtering conditions (nitrogen gas percentage), to achieve the desired balance between specific resistance and TCR characteristics
Solution Approach 2:
The patent introduces local compositional variations by adding specific valve metals or transition metals to different regions of the resistive material system, allowing different areas to contribute different properties (some providing high resistivity, others providing stable TCR)
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 solution enables thin-film resistors with higher resistance values than conventional ones while maintaining TCR characteristics around zero, enhancing reliability and stability, and allows for reduced chip sizes without compromising performance.
Implementation Method 1
A target containing a thin-film resistive material is sputtered so that the material is deposited on the surface of a substrate as a resistive film
Implementation Method 2
the resistive film is then subjected to heat treatment under an inert gas atmosphere such as nitrogen or argon
Data Source
AI summary
Provided is a thin-film resistor that has a higher resistance value than the conventional thin-film resistors while retaining excellent TCR characteristics. The thin-film resistor includes a substrate, a pair of electrodes formed on the substrate, and a resistive film connected to the pair of electrodes. The resistive film includes a first resistive film and a second resistive film, the second resistive film having a different TCR from that of the first resistive film, and each of the first resistive film and the second resistive film contains Si, Cr, and N as the main components.