Laminated Thin Film Temperature Sensor for High TCR
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Solution Overview
Problem
Existing temperature sensors in hard disk drives and magnetic recording devices face challenges in achieving a high signal noise ratio due to low temperature coefficient of resistance (TCR) in metal thin films, primarily caused by surface and interface scattering, which reduces the effectiveness of contact detection and thermal asperity detection.
Innovation Solution
The development of laminated metal and metal/oxide thin films with a conductive layer and a specular or seed layer, where the thickness of the conductive layer is approximately equal to or less than the mean-free-path of electrons, and the use of multilayer structures and optimized fabrication methods at elevated temperatures to enhance the TCR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metal thin films are used for temperature sensing, then the device can detect temperature changes, but the temperature coefficient of resistance (TCR) is low due to surface and interface scattering
Solution Approach 1:
The patent divides the temperature sensing function into multiple layers: a conductive material layer for temperature sensing and a specular layer to reduce scattering. This segmentation allows each layer to perform its specific function optimally, with the conductive layer providing temperature response and the specular layer minimizing electron scattering at interfaces.
Solution Approach 2:
The patent introduces a specular layer as an intermediary between the conductive material and the environment. This intermediate layer acts as a mediator that reduces the harmful surface and interface scattering effects on electron transport, thereby enhancing the TCR of the temperature sensor without compromising the temperature sensing capability.
2Measurement precision
If the conductive layer thickness is reduced to enhance TCR, then the temperature coefficient of resistance increases, but the sheet resistance also increases
Solution Approach 1:
The patent creates a composite structure combining a conductive material layer with a specular layer. This composite material approach allows the thin conductive layer to maintain high TCR while the specular layer provides a low-resistance pathway for electrons, effectively reducing the overall sheet resistance of the structure despite the thinness of the conductive layer.
Solution Approach 2:
The patent optimizes the thickness parameters of both the conductive layer and specular layer to achieve the desired balance between TCR and sheet resistance. By carefully controlling these dimensional parameters, the structure achieves maximum TCR enhancement while maintaining acceptable sheet resistance levels for reliable temperature sensing operation.
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
This approach significantly increases the TCR of temperature sensors by reducing the resistance and enhancing the signal noise ratio, enabling more effective detection of head-media contact and thermal asperities, with TCR values ranging from 0.2 to 0.5%/°C and sheet resistances between 3 to 8 ohms.
Implementation Method 1
The first layer has a thickness approximately equal to or less than a mean-free-path of an electron in the conductive material of the first layer
Implementation Method 2
a first layer comprising a conductive material and having a TCR
Data Source
AI summary
An apparatus comprises a head transducer and a resistive temperature sensor provided on the head transducer. The resistive temperature sensor comprises a first layer comprising a conductive material and having a temperature coefficient of resistance (TCR) and a second layer comprising at least one of a specular layer and a seed layer. A method is disclosed to fabricate such sensor with a laminated thin film structure to achieve a large TCR. The thicknesses of various layers in the laminated thin film are in the range of few to a few tens of nanometers. The combinations of the deliberately optimized multilayer thin film structures and the fabrication of such films at the elevated temperatures are disclosed to obtain the large TCR.