Won-Hyeog Jin

Ultrahigh-density phase-change data storage without the use of heating.

Non-volatile memories based on scanning probes offer very high data densities, but existing approaches require the probe to be heated, which increases the energy expenditure and complexity of fabrication. Here, we demonstrate the writing, reading and erasure of an ultrahigh-density array of nanoscopic indentations without heating either the scanning probe tip or the substrate. An atomic force microscope tip causes microphase transitions of the polystyrene-block-poly(n-pentyl methacrylate) of a block copolymer to occur at room temperature by application of pressure alone. We demonstrate a data storage density of 1 Tb in(-2), which is limited only by the size of the tip. This demonstration of a pressure-based phase-change memory at room temperature may expedite the development of next-generation ultrahigh-density data storage media.

Microcantilevers integrated with heaters and piezoelectric detectors for nano data-storage application

A thermomechanical writing system and a piezoelectric readback system have been demonstrated using silicon cantilevers integrated with heaters and piezoelectric sensors for a low-power scanning-probe-microscopy data-storage system. A thin polymethylmethacrylate film has been used as a media to record data bits of 50 nm in diameter and 25 nm in depth using the silicon cantilever. The sensitivity of 0.22 fC/nm was also obtained using the fabricated cantilever. Finally, to obtain readback signals using the piezoelectric cantilever, a patterned oxide wafer with 30 nm depth was scanned to show the distinctive charge signals.

Integrated nitride cantilever array with Si heaters and piezoelectric detectors for nano-data-storage application

In this paper, a silicon nitride cantilever integrated with silicon heater and piezoelectric sensor has been firstly developed to improve the uniformity of the initial bending and the mechanical stability of the cantilever array for thermo-piezoelectric SPM (scanning probe microscopy) -based data storages. This nitride cantilever shows thickness uniformity less than 2%. Data bits of 40 nm in diameter were recorded on PMMA film. The sensitivity of the piezoelectric sensor was 0.615 fC/nm after poling the PZT layer implying that indentations less than 20 nm in depth can be detected. For high speed operation, 128 /spl times/ 128 probe array was developed.

Micro cantilevers with integrated heaters and piezoelectric detectors for low power SPM data storage application

In this research, silicon cantilevers with integrated heaters and piezoelectric sensors have been studied for thermomechanical writing and piezoelectric readback on a polymer film, for low power SPM (Scanning Probe Microscopy) data storage system. Data bits of 100 nm in diameter have been recorded on a Poly Methyl Methacrylate (PMMA) film. The sensitivity of 0.22 fC/nm is obtained. Finally, the silicon cantilever with piezoelectric sensor was used to obtain charge readback signal using the grating with 30 nm depth, and the sensing ability of the piezoelectric cantilever was successfully demonstrated. The charge output based on the topography of the film was obtained, and the positive and negative peak of the charge corresponded to the slope of the grating.

Fabrication and Simulation of Silicon Nitride Cantilever for Low Power Nano-Data-Storage

An AFM tip silicon nitride cantilever was fabricated to observe thermal characteristics in order to increase data writing speed and lower power consumption. By using time dependent resistance and temperature dependent resistance curves of heating tip in experimental results, the changes of temperature on the tip were compared with simulated data. It was found that the thermal time constant of silicon nitride cantilever was 48 μs at 4 V input for 20 μs and 37 μs at 5 V input for 25 μs. Throughout the design modification, the model which has 0.5 μm, 2:1, 1000 Ω/□ shows the lowest power consumption. By changing the heating time, the power consumption of 0.158 mW and thermal time constant of 75 ns were finally observed.Copyright

2‐Dimension PZT Cantilever Array with New Piezoelectric Readback Method for Low Power and High Speed Nano‐Data‐Storage Application

In this research, 2‐dimensional PZT cantilever array with integrated heaters and piezoelectric sensors, called, ‘thermo‐piezoelectric’ cantilever has been fabricated, and studied for thermo‐mechanical writing and piezoelectric readback on a polymer film for high speed and low power SPM (Scanning Probe Microscopy) based nano‐data‐storage system. Power consumption could be considerably low in read/write process due to new piezoelectric readback method and the selection of low Tg polymer media. The sensitivity of 0.22 fC/nm is obtained. The silicon cantilever with piezoelectric sensor was used to obtain charge readback signal using the pattern SiO2 with 100‐nm depth. To improve the data rates, we have developed and fabricated a (100×100) 2‐D thermo‐piezoelectric cantilever array for parallel operation and we introduce a simple equivalent model of PZT sensor for estimating data rate of thermo‐piezoelectric cantilever and circuit analysis is accomplished using this model.