Data Storage

Publications & Papers

A Non-Destructive Metrology Solution for Detailed Measurements of Imprint
Templates and Media

Source: SPIE Photomask Technology, September 2009, California, USA
Authors: Jeffrey Roberts, Linlin Hu (n&k Technology); Torbjörn Eriksson, Kristian Thulin,
Babak Heidari (Obducat)
Abstract: This study investigates a non-destructive optical metrology technique that furnishes measurement solutions for hard drive discrete track recording (DTR) and bit atterned media (BPM) templates and imprints. From the measurement and analysis of polarized reflectance and transmittance, feature height and profile of DTR and BPM templates and imprints, as well as residual layer thickness of imprints, are accurately determined, and uniformity maps of these parameters are produced in a fraction of a minute. Simulations of theoretical polarized reflectance and transmittance, relating to next generation structures, demonstrate that the optical metrology solution has capability for future products.

 


Ultra-Sensitive Optical Metrology for Hard Disk DTR and BPM Imprints

Source: SPIE Lithography Asia, November 2009, Taipei, Taiwan
Authors: Jeffrey Roberts, Linlin Hu, Iris Bloomer (n&k Technology); Shih-Fu Lee,
Yongdong Liu (Seagate)
Abstract: With pitches in the double-digit nanometer range and depths in the single-digit nanometer range, superior sensitivity is a necessary metrology requirement for patterned media. Variations in depth, CD, and sidewall angle on the order of the desired measurement precision will change the measured raw data by a miniscule amount, around one per cent or less. It is shown that the required sensitivity can be achieved with polarized broad band reflectance and transmittance incorporating optimized signal-to-noise and analysis based on Rigorous Coupled Wave Analysis (RCWA) in conjunction with the Forouhi-Bloomer dispersion equations for optical properties, n and k. The measurement capabilities are demonstrated with simulations and examples of various DTR and BPM structures.

 


Characterization of Perpendicular Magnetic Recording Media using Broadband Optical
Reflectometry

Source: Diskcon Conference, September 2007, California, USA
Authors: Linlin Hu, Alexander Gray and Mehdi Balooch
Abstract: A broadband reflectometer is used for perpendicular magnetic media films thickness determination. Carbon overlayer thickness with angstrom accuracy is solely determined using deep-UV response and shown to be decoupled from varying underlayer films. The two top magnetic layers thickness and their optical properties are evaluated by the entire spectrum.

 


Examining Metrology Solutions for Overcoats

Source: Data Storage (2001)
Authors: I. Bloomer, J. Lam (n&k Technology)
Abstract: This articlereports on the measurements of ultra-thin Diamond-Like Carbon (DLC) films, and DLC / a-Si film stacks.

The reported values of n and k are then correlated with other measurement techniques to allow the monitoring of N and H content in the DLC film using an n&k Analyzer.

 


Thin-film Metrology- it’s not just for R&D anymore

Source: Data Storage (2000)
Author: A.R. Forouhi
Abstract: Describes Metrology as an advanced method for process control.

 


A Fast, Easy Way to Measure the Thickness of DLC Films

Source: Data Storage (1999)
Authors: G.G. Li, H. Zhu, D. Harrison, A.R. Forouhi (n&k Technology); W. Xu (Seagate)
Abstract: This article, authored by Dr. George Li, Honwei Zhu, Dr. Dale Harrison, and Dr. Rahim Forouhi of n&k Technology, and Dr, Weilu Xu of Seagate Media, describes the characterization of ultra-thin ( substrates, including SiO2 / Si; NiP / Al; and a magnetic alloy X / Cr / NiP / Al. Results from the n&k Analyzer are also compared to those from an AFM, and a stylus profiler.

 


Characterizing Film Stacks Comprising GMR Heads

Source: Vacuum & Thin film (1999)
Authors: I. Bloomer, A.R. Forouhi, G.G. Li, H. Zhu (n&k Technology); S. Prakash (Applied Magnetics)
Abstract: This article, authored by Dr. Iris Bloomer, Dr. Rahim Forouhi, and Dr. George Li of n&k Technology, and Helen Zhu and Shiva Prakash of Applied Magnetics, describes the “n&k Method”, as well as the characterization of several films and multi-layer stacks used to manufacture giant magnetoresistive (GMR) heads, including: AlN; Al2O3; Ta2O5 / Ta / SiO2; NiFe / Ta / SiO2; NiFe / Ta / Al2O3; and Ta2O5 / Ta / NiFe / Ta / SiO2. Additionally, thickness results obtained from the n&k Analyzer are compared with results from XRR and AFM.

 


Cross-Linking Thin Film Characterization Technique for Data Storage, Semiconductor,
and Flat Panel Display Devices

Source: SPIE Photonic (1999)
Authors: I. Bloomer, D. Harrison (n&k Technology ); S. Prakash (DAS); K. Zhang (EG&G); S. Lian (Motorola)
Abstract: The message of this paper is that the n&k Analyzer is a universal thin film characterization tool. The applicability of the n&k Analyzer various films used in different industries are described in this article by Dr. Shiva Prakash of DAS Devices, Dr. Sean Lian of Motorola, and Dr. Zhang of EG&G.

 


Accurately Measuring Thickness and Optical Constants of Thin Films Comprising Data
Storage Peripherals

Source: Datatech (1998)
Authors: A.R. Forouhi, G.G. Li, I. Bloomer (n&k Technology)
Abstract: The article entitled, “Accurately Measuring Thickness and Optical Constants of Thin Films Comprising Data Storage Peripherals”, describes the n&k Analyzer’s ability to characterize various types of materials. These materials include Dye, ZnS-SiO2, AgInSbTe, TbFeCo, AlN, SiNx, Ta2O5, and NiF, CoCrTa mag layer, PC and PET substrates, used for different CDs (CD-R, CD-RW, DVD), Media (Magnetic disk and tape, Magneto Optical disk), and thin film heads manufacturing.

 


Optical Characterization of Carbon Overcoats

Source: Data Storage (1997)
Authors: J. Ager III (LBL); B. Marchon (Seagate); R. Forouhi, I. Bloomer (n&k Technology)
Abstract: Various “types” of carbon films are used as protective overcoats on magnetic disks and on thin film heads. These films are hydrogenated amorphous carbon (a-C:H), carbon nitride (CNx), or carbon containing H and N (C:HN). Generally, the processing conditions are set such that the microstructure of the resulting film resemble that of diamond. Thus, these films are also referred to as Diamond Like Carbon (DLC). Depending on application, single or multilayer carbon films are deposited on disks and heads. Also, the industry trend is towards deposition of ultra-thin (leader in measurement and characterization of ultra thin carbon, single or multilayer a-C:H, CNx, C:HN, DLC films.

 


Optical Characterization of Nitrogenated Carbon Overcoats

Source: Thin Solid Films (1997)
Authors: R.W. Chia (Western Digital); E. Li (Alcashic Memories); S. Sugi (Kubota); H. Zhu, A.R. Forouhi, I. Bloomer (n&k Technology)
Abstract: In this paper, authored by Ray Wen-Jui Chia of Western Digital Corporation, Eric Li of Akashic Memories, Seiki Sugi of Kubota Corporation, and Dr. George Li, Helen Zhu, Dr. Rahim Forouhi, and Dr. Iris Bloomer of n&k Technology, a method is presented for monitoring the nitrogen content of CNx carbon overcoats. n and k values reported by the n&k Analyzer are correlated with N% as measured by X-ray photoelectron spectroscopy (XPS), to provide a rapid determination of N content for the manufacturing environment.

 


Characterizing the Carbon Overcoat on Magnetic Disks

Source: n&k Technology, Inc.
Abstract: Describes the correlation of k value vs. Hydrogen content in DLC coatings, using an n&k Analyzer.

 


Accurate Measurement of Thickness and Optical Constants of Thin Films Comprising
CDs, CD-Rs, CD-RWs, Magnetic Tapes, DVDs, etc.

Source: n&k Technology, Inc.
Abstract: Presents data from the optical characterization of various films used on all types of data storage peripherals, including the media listed above, as well as magnetic read/write heads.

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