Seagate Technology Incorporated

Sundeep Chauhan

Lawrence Matthias Bryant

David S Kuo

Neil Deeman

Barmeshwar Vikramaditya

Christopher Formato

Mehmet Fatih Erden

Koichi R Wago

David Marcus Tung

Alexei Hiram Sacks

David Shiao-Min Kuo

Qiang Ling

Kim Yang Lee

Rene Johannes Marinus Van De Veerdonk

Patrick J Korkowski

Alexander Kantorov

Barmeshwar Vikaramaditya

Provided herein is a method, including forming a first template including a first pattern, wherein forming the first template includes self-assembly of diblock copolymers guided by an initial pattern; forming a second template including a second pattern, wherein the second pattern corresponds to a servo pattern; and forming a master template from the first template, wherein the master template includes one or more portions of the first pattern combined with the second pattern.

Imprint template and methods thereof

The relative trajectory of a transducer head over bit-patterned media (BPM) may be skewed with respect to a down-track direction on the media (i.e., skew error). In order to resolve the skew error, the presently disclosed technology measures the skew error without adding additional patterning on the media. A detector circuit detects a sequential series of data bits on a storage media. The sequential series of data bits alternate between at least two tracks on the storage media. The sequential series of data bits are sent to a timing circuit, which sets a time stamp indicating when each data bit is received using, for example, a delay chain or a voltage ramp. A time elapsed between receiving a first data bit, a second data bit, and a third data bit is tracked. Transducer head skew is adjusted based on a signal containing the time elapsed between the bits.

Skew compensation signal

A magnetic storage medium comprises a plurality of discrete magnetic elements and first and second adjoining servo sectors. Each of the servo sectors comprises first and second rows of the discrete magnetic elements extending in a track direction. The second row of the discrete magnetic elements are stacked relative to the discrete magnetic elements of the first row in a cross-track direction that is perpendicular to the track direction. The discrete magnetic elements of the first servo sector are staggered in the cross-track direction relative to the discrete magnetic elements of the second servo sector.

Bit patterned magnetic storage medium

A method for encoder frequency-shift compensation includes determining frequency values of an input encoder signal, determining repeatable frequency-shifts of the frequency values and generating a frequency-shift compensated clock using the repeatable frequency-shifts. A frequency-shift compensated clock includes a synthesizer configured to generate a frequency-shift compensated clock signal using repeatable frequency shifts and encoder clock signals.

Method for encoder frequency-shift compensation

The embodiments disclose a method for encoder frequency-shift compensation, including, determining frequency values of an input encoder signal, analyzing an encoder index clock signal and the input encoder signal to determine values of frequency-shifts and compensating for the values of the frequency-shifts to generate a frequency-shift compensated clock.

Method for encoder frequency shift compensation

The eccentricity of tracks defined on a rotating bit patterned media are measured using a readback signal, and the measured eccentricity may be used to control centering of the disk relative to a rotational spindle and/or to control movement of a read/write head relative to a selected track on the disk.

Measurement of track eccentricity on bit patterned media

Extracting transducer position information from bit patterned magnetic media includes providing a magnetic storage medium having at least one data array with multiple discrete and separated recording bits and providing the transducer adjacent the data array. A readback signal dependent upon the multiple recording bits is generated with the transducer. Determining the transducer position information further includes generating at least a first position signal and a second position signal from the readback signal.

Extraction of transducer position information from bit patterned magnetic media

An apparatus and method for detecting a phase difference between an input signal and a reference signal in an all-digital phase locked loop (PLL) are provided. In a preferred embodiment, an N-stage tapped delay line and N-bit parallel latch are used to create a snapshot of the input signal by latching the output of the tapped delay line using the reference signal to clock the latch. An edge detector and encoder circuit translate the latched snapshot into a numerical phase difference value. A difference between this phase difference value and a desired phase difference is calculated and then added to an accumulator. The result in the accumulator is a numerical phase error value that can be fed to a numerically controlled oscillator (NCO). The output of the NCO can, in turn, be fed back into the phase/frequency comparator as the input signal, thus forming a fully-digital PLL.

High speed digital phase/frequency comparator for phase locked loops

A patterned recording media comprises a segment and a null pattern formed in the segment. The segment comprises first and second rows of discrete magnetic elements separated by a non-magnetic material, and a row of non-magnetic material positioned between the first and second rows. The null pattern comprises consecutive groups of the discrete magnetic elements in the first and second rows of the segment. Each group in the first row has a magnetic polarity that is opposite the magnetic polarity of adjoining groups in the first row. Each group in the second row has a magnetic polarity that is opposite the magnetic polarity of adjoining groups in the second row.

Null servo pattern for bit-patterned media

Embodiments of the invention generally provide an electron beam substrate processing system. In one embodiment, the present invention provides an electron beam substrate processing system where a spindle shaft used to rotate substrates during processing includes at least one optical encoder wheel assembly. The optical encoder wheel assembly is configured to provide rotational speed data signal to a rotational speed control system and a pattern generation clock circuit configured to a provide an angular pattern generator clock signal and to a pattern generator circuit. The pattern generation circuit is configured to control modulation of an electron beam used for substrate processing. In one aspect of the present invention, while the spindle shaft is rotated at a constant linear velocity, the pattern generation circuit controls the modulation of an electron beam such that written mark lengths are sized to be about constant in angular dimension.

Method and apparatus for constant linear velocity electron beam substrate processing

A rotating recording device, such as an electron beam recorder, is provided with a dual encoder arrangement. A first encoder is employed as a spindle motor controller and located at a first end of a spindle. A second encoder is mounted at a turntable adjacent to a recording surface and used as a position, velocity or clock source for recording the pattern on the substrate. Eccentricity of the mounting of the second encoder is measured against the more accurately mounted spindle control encoder and compensated by a digital clock generating system using a digital phase locked loop.

Rotating recorder with dual encoder arrangement having eccentricity compensation

Embodiments of the invention generally provide an electron beam substrate processing system. In one embodiment, the present invention provides an electron beam substrate processing system where a spindle shaft used to rotate substrates during processing includes two encoder wheels. One encoder wheel is configured to provide a rotational speed data signal to a rotational speed control system. Another encoder wheel is configured to provide a pattern generator clock signal at a higher frequency than the rotational speed data signal to a pattern generator. In one embodiment of the present invention, at least one of the encoder wheels is positioned adjacent the substrate to minimize torsional and differential movements between the at least one encoder wheel and the substrate.

Method and apparatus for electron beam processing of substrates

Embodiments of the invention generally provide an electron beam substrate processing system. In one embodiment, the present invention provides an electron beam substrate processing system where a spindle shaft used to rotate substrates during processing includes at least one optical encoder wheel assembly. The optical encoder wheel assembly is configured to provide rotational speed data signal to a rotational speed control system and a pattern generation clock circuit configured to a provide a corrected pattern generator clock signal to a pattern generator circuit. The pattern generation circuit is used to control modulation of an electron beam used for substrate processing. In one aspect of the present invention, repeatable deviations of the rotational speed are measured and processed during substrate processing to correct for such repeatable deviations to increase substrate pattern writing accuracy.

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Fremont, CA, United States of America

Sundeep Chauhan