Erwin Rinaldo Meinders

Multilevel Information Storage in Ferroelectric Polymer Memories

Multibit memory devices based on the ferroelectric copolymer P(VDF-TrFE) (poly-(vinylidenefluoride-trifluoroethylene)) are presented. Multilevel microstructures are fabricated by thermal imprinting of spin-coated ferroelectric polymer film using a rigid Si template. Multibit storage in capacitors and thin-film transistor memory is realized by implementing imprinted ferroelectric polymer films as the insulator and gate dielectric layers, respectively. Copyright

Determination of the crystallisation kinetics of fast-growth phase-change materials for mark-formation prediction

A mark simulation tool for fast-growth phase-change materials was developed to predict the formation and erasure of amorphous marks in phase-change discs that are based on doped Sb2Te compositions. One of the main challenges of such a simulation tool is the accurate determination of the input parameters. The thermal conductivity of the thin films in the recording stack was determined from melt-threshold experiments in combination with numerical modelling. The crystallisation process, modelled as crystal growth from a crystalline-amorphous interface, is governed by the temperature-dependent velocity of crystal growth. In this paper, we discuss a procedure for measuring the low-temperature velocity of crystal growth from the size of an amorphous mark and the time required for complete erasure under isothermal conditions. Furthermore, to determine the velocity of crystal growth in the temperature range encountered during recording conditions, we performed time-resolved erasure experiments in combination with numerical modelling. The derived time-dependent growth velocity was used in a numerical model to simulate the formation of amorphous marks. Transmission electron microscopy (TEM) measurements of recorded marks were compared to predicted mark shapes to validate the numerical model.

Numerical simulation of mark formation in dual-stack phase-change recording

Dual-stack phase-change recording is an option to further increase the data capacity of rewritable optical disks. Such disks consist of two recording stacks that are both recorded and read from the same side of the disk. Consequently, the first recording stack needs therefore to be semitransparent to allow recording in the second recording stack. Thick nontransparent metal layers can therefore not be used in the first recording stack, which makes the first recording stack the most challenging stack from a thermal point of view. A numerical model based on crystal growth was developed to study formation and erasure of amorphous marks in phase-change stacks that are based on fast-growth doped SbTe phase-change materials. The validity of the model was demonstrated from transmission electron microscopy analyses of recorded marks that showed a good correspondence with the calculated mark shapes in a conventional single-stack recording stack. The model was subsequently applied to analyze formation and erasure of marks in slow-cooling phase-change stacks for digital versatile disk, (DVD) and digital video recording (DVR) recording conditions. The effect of the recording velocity, the erase power, and the crystal growth velocity on the erasability of amorphous marks was simulated. The calculated phenomena are in good agreement with the phenomena observed from DVD and DVR erasability measurements. Mark formation in slow-cooling recording stacks is characterized by severe recrystallization during writing. Two possible solutions are indicated in this article, aiming at reducing the heat accumulation and the resulting recrystallization during writing of amorphous marks. Additional semitransparent heat sinks improve the mark formation considerably but also require higher write powers. Another solution is the application of modified write strategies. Modeling and recorder results are discussed for both approaches.

Polymer substrates for flexible electronics: achievements and challenges

Flexible electronics technology can potentially result in many compelling applications not satisfied by the rigid Si-based conventional electronics. Commercially available foils such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) have emerged as the most suitable polymer materials for wide range of flexible electronics applications. Despite the enormous progress which has been recently done on the optimization of physical and mechanical properties of PET and PEN foils, their dimensional stability at the micro-scale is still an issue during patterning of wiring by means of lithography. Consequently, the measurement of in-plane micro-deformation of foil is of great importance for understanding and predicting its thermal, hydroscopic and mechanical behaviour during processing.

Phase-Transition Mastering of High-Density Optical Media

A new phase-transition mastering (PTM) process was developed for Blu-ray Disc read-only memory (BD-ROM) mastering. Results obtained with both a 266 and 405 nm laser beam recorder (LBR) are discussed in this paper. The feasibility of BD-ROM mastering was successfully demonstrated on both LBRs. With the insight that 25 Gbytes BD-ROM can be mastered with a 405 nm wavelength LBR, the availability of the 266 nm wavelength LBR opened the route to explore PTM of near-field data densities. First experiments indicate that the PTM process is also suitable for mastering data densities beyond 25 Gbytes data density.

Recent Developments in Thermal Modelling of High-Speed Dye Recording

We discuss a generic method to validate a numerical model that can be applied to high-speed dye recording. The method is based on the determination of transition powers that correspond to the onset of pit formation. The mechanism of pit formation is discussed in terms of the decomposition of the recording dye and the softening of the polycarbonate substrate. The decomposition temperature of compact disc (CD) and digital versatile disc (DVD) dyes was measured with two different methods, involving heating rates that approach those encountered during recording. The softening temperature of polycarbonate was also measured. The laser powers required for the onset of dye decomposition and softening of the polycarbonate-dye interface were determined from continuous-writing (DC-write) reflection measurements for 1X-40X CD-R recording and 1X-10X DVD+R recording. In addition, transition powers were obtained from atomic force microscopy (AFM) analyses of written tracks. The DC-reflection and AFM-topography measurements appear to collapse onto one generic master curve for the entire range of tested recording velocities for each type of CD and DVD. From the measured temperatures for the onset of dye decomposition and polycarbonate softening, transition powers were also calculated with a numerical model of the multilayer recording stack. Numerical results are compared with experimental values for a CD and DVD type of disc.

Flexible Biochips for Detection of Biomolecules

Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel microarray patterns of binding sites on rigid substrates, such as glass or silicon. Thin plastic substrates are promising flexible alternatives because of the possibility for large-area roll-to-roll manufacturing of disposable chips at lower costs. Mature optical lithography technology faces many challenges when used to pattern flexible foils as a result of the substrate instabilities, especially at higher temperatures. In this work, flexible biochips with gold electrode patterns were fabricated on thin polyethylene naphthalate (PEN) foils using photolithography. The gold electrode structures of the chips were manufactured by direct metal patterning and by lift-off processing. Both methodologies resulted in well-defined electrode patterns as concluded from optical microscopy and scanning electron microscopy (SEM) characterization and resistance measurements. The biochips were successfully employed for the electrical and optical detection of DNA molecules. The DNA detection was based on the immobilization of capture DNA between electrode gaps, hybridization with biotin-labeled target DNA, and enzymatic silver enhancement.

Thermal Cross-Erase Issues in High-Data-Density Phase-Change Recording

We report on the numerical simulations of high-data-density phase-change recording (DVR-blue and DVR-red) in order to analyse the phenomenon of thermal cross-erase in land/groove recording. In particular, if a maximum data capacity is pursued, which involves a small radial track pitch, thermal cross interference may become an important issue. The question of whether or not the temperature distributions and the related thermal cross-erase probability scale with the optical spot size is addressed. Two different thermal models (a planar model and a land/groove model) were used in which laser heating was simulated. Reliable temperature predictions and related trend analyses require a proper model and accurate input parameters. The thermal conductivity of the different layers in the stack was obtained from measurements performed with a time-resolved static tester setup in combination with a novel melt-threshold method. Since thermal cross-erase is dependent on the temporal temperature distribution in the stack, we analysed the most important parameters that possibly contribute to a reduction of the temperature, and thus the cross-erase probability, in the adjacent track.

Liquid Immersion Deep-UV Optical Disc Mastering for Blu-ray Disc Read-Only Memory

The liquid immersion mastering technique has been successfully applied to the mastering of read-only memory (ROM) discs for the Blu-ray disc (BD) system. Replicated discs with a density corresponding to 25 GB in a single layer on a 12 cm disc showed a bottom jitter of less than 5%. Results concerning process latitude and disc uniformity are presented. A full-format 25 GB ROM disc containing over 2 h of high-definition video content has been mastered according to the BD target specification. The results obtained for a reduced channel bit length show the potential of liquid immersion mastering for densities beyond 31 GB per layer.

Melt-threshold method to determine the thermal conductivity of thin films in phase-change optical recording stacks

We report on the dynamic melt-threshold method for the in situ determination of the effective thermal conductivity of thin layers in phase-change optical recording stacks. The method is based on the systematic variation of some of the thermal parameters of the thin films in the recording stack such that the temperature of the phase-change layer, calculated with a multilayer numerical model, equaled the measured melt temperature of the phase-change material. The laser power that causes the onset of melting, the melt-threshold power, was determined from the detectable reflection difference between the crystalline and molten state of the phase-change film and served as input for the model calculations. Melt-threshold experiments were performed for different recording velocities, stack structures, layer thicknesses and optical spot sizes. The melt-threshold method provided a consistent set of thermal parameters that accurately predicts the temperature distribution in a recording stack during erasing and recor...