Asymmetric Interference Waveguides for NFT Wafer Characterization
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Solution Overview
Problem
Current methods for characterizing near field transducer performance in energy-assisted magnetic recording systems are inefficient and costly, often resulting in poor signal-to-noise ratios and inadequate device characterization when performed at the bar or slider level, making it difficult to optimize NFT parameters such as core-NFT spacing, size, shape, and material properties.
Innovation Solution
A system utilizing asymmetric interference waveguides at the wafer level, which includes a light source, input grating, splitter, and waveguide arms to induce a preselected phase difference in light reaching the surface plasmon receptor, coupled with a light detector to determine optimal wavelength and adjust physical characteristics for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If device characterization is performed at bar or slider level, then device performance can be tested, but the process becomes time consuming and expensive due to many backend processes
Solution Approach 1:
The patent performs NFT characterization at wafer level before the NFTs are mounted onto bars or sliders. By conducting measurements preliminarily at the wafer stage, the need for time-consuming backend processes (lapping, mounting) is eliminated, significantly reducing testing time while maintaining characterization capability
Solution Approach 2:
The patent segments the characterization process from the final assembly process. Instead of characterizing only after complete assembly (bar/slider level), it enables independent characterization at the wafer level, allowing parallel processing and reducing overall testing time
2Measurement precision
If device characterization is performed at bar or slider level, then device performance can be tested, but the process becomes expensive due to many backend processes
Solution Approach 1:
By performing characterization at wafer level before final assembly, the patent avoids the need for expensive backend processes such as lapping and specialized mounting equipment, significantly reducing manufacturing costs while maintaining measurement capability
Solution Approach 2:
The patent extracts the characterization function from the final assembly process and implements it independently at the wafer level, eliminating the need for expensive backend processing equipment and reducing overall manufacturing costs
3Measurement precision
If a single disk NFT or multiple disk NFTs are configured to interact with a conventional waveguide mode, then device characterization can be attempted, but the signal to noise ratio is poor
Solution Approach 1:
The patent employs an asymmetric waveguide structure with different arm lengths to create controlled phase differences between interfering beams. This asymmetric design enhances the interference signal strength and improves signal-to-noise ratio compared to symmetric conventional waveguide configurations
Solution Approach 2:
The patent utilizes optical interference (analogous to vibration principles) by creating constructive and destructive interference patterns through the asymmetric waveguide. The controlled phase differences generate enhanced interference signals that improve measurement sensitivity and signal-to-noise ratio
4Measurement precision
If a pump probe system is used for testing a single NFT on a wafer, then device characterization can be attempted, but the device characterization capabilities are generally poor
Solution Approach 1:
The patent implements a multi-functional waveguide system that can characterize multiple NFTs simultaneously on a wafer. The system serves multiple purposes: wavelength tuning, interference pattern generation, and simultaneous multi-device characterization, reducing overall system complexity compared to multiple pump-probe systems
Solution Approach 2:
The patent combines multiple characterization functions (wavelength tuning, interference measurement, multi-device testing) into a single integrated waveguide system. By merging these functions, the system achieves better characterization capability without proportionally increasing complexity
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 enables precise and accurate characterization of near field transducers, enhancing signal-to-noise ratio and reducing testing cycles by allowing for wavelength tuning and precise adjustment of manufacturing processes, leading to optimized performance characteristics.
Implementation Method 1
an input grating configured to receive light from the light source
Implementation Method 2
a splitter configured to receive the light from the input grating, the splitter configured to split the light into the first waveguide arm and the second waveguide arm
Implementation Method 3
the first and the second waveguide arms are configured to induce a preselected phase difference in light arriving at the surface plasmon receptor
Implementation Method 4
the first and the second waveguide arms are configured to induce a preselected phase difference in light arriving at the surface plasmon receptor
Implementation Method 5
a surface plasmon receptor optically coupled to the first waveguide arm and the second waveguide arm and configured to receive light from the first waveguide arm
Implementation Method 6
a first output grating coupled to the third waveguide arm
Data Source
AI summary
Systems and methods and apparatuses for characterizing near field transducer performance at wafer level using asymmetric interference waveguides are provided. One such system includes a light source, an input grating configured to receive light from the light source, a first waveguide arm and a second waveguide arm, each configured to receive the light, a surface plasmon receptor optically coupled to the first waveguide arm and the second waveguide arm and configured to receive light from the first waveguide arm in a first direction and the second waveguide arm in a second direction opposite of the first direction, where the first and the second waveguide arms are configured to induce a preselected phase difference in light arriving at the surface plasmon receptor, and an output grating optically coupled to the surface plasmon receptor, and a light detector coupled to, and configured to detect light from, the first output grating.