Search

A microelectromechanical system actuator based on thermophoretic, or Knudson, forces is proposed using analytical calculations. It can potentially execute scanning or spinning motions of a body that is not mechanically attached to the reference substrate. For a silicon device of 100-[micro]m diameter, it is calculated that it can be levitated at a distance of about 0.5 [micro]m from a substrate and that it can execute scanning motion and use quasi-springs by laterally acting thermal forces. In this way, an engine with spinning motion of a floating body having a diameter of 200/[micro]m with up to 5 kHz can be achieved. [2008-0013] Index Terms--Microactuators, microelectromechanical devices, micromotors, thermophoresis.

We have developed a generic cost-efficient CMOS-compatible heterogeneous device integration method at wafer-scale level. This method enables the distribution of devices from one to numerous wafers using selective transfer technology. We have applied this method for the distribution of atomic force microscopy (AFM) cantilevers and successfully demonstrated the population of multiple wafers from one source wafer. The distribution function has been designed such as to populate 42 wafers with only one source wafer. This CMOS back-end-of-the-line compatible method is particularly suitable for microelectromechanical systems and integrated circuits. Electrical interconnects are compatible with this technology. We present the concept, the selective transfer method, including a laser ablation technique used for the transfer, as well as the process and results of the application for AFM cantilever distribution. [2007-0135] Index Terms--Atomic force microscopy (AFM), heterogeneous device integration, systems-on-chip, wafer-scale 3-D integration.

We describe a planar microelectromechanical systems (MEMS)-based x/y nanopositioner designed for parallel-probe storage applications. The nanopositioner is actuated electromagnetically and has x/y motion capabilities of [+ or -] 60 [micro]m. The mechanical components are fabricated from a single-crystal silicon wafer using a deep-trench-etching process. To render the system robust against vibration, we utilize a mass-balancing concept that makes the system stiff against linear shock, but still compliant for actuation, and therefore results in low power consumption. We present details of the finite-element model used to design the device as well as experimental results for the frequency response, actuation, and vibration-rejection properties of the nanopositioner. Index Terms--Actuators, atomic force microscopy, microelectromechanical devices, motion control, motors.

We have developed a robust, CMOS back end of the line (BEOL) compatible, wafer-scale device transfer, and interconnect method for batch fabricating systems on chip that are especially suitable for MEMS or VLSI-MEMS applications. We have applied this method to transfer arrays of 4096 free-standing cantilevers with good cantilever flatness control and high-density vertical electrical interconnects to the receiver wafer (typically CMOS). Such an array is used in a highly parallel, scanning-probe-based data-storage system, which we internally call 'millipede.' A very high-integration density has been achieved, even for wafer-scale transfer, thanks to the interlocking nature of the interconnect structure, which provides easy alignment with an accuracy of 2 [micro]m. The typical integration density is 100 cantilevers/[mm.sup.2] and 300 electrical interconnects/[mm.sup.2]. Note that only the cantilevers, not a chip with cantilevers, are transferred and, unlike flip-chip technology, our method preserves the device orientation, which is crucial for MEMS applications, where often the MEMS device should have access to its environment (in our case, the cantilever tips are in contact with the storage medium). After device transfer, the system is mechanically and electrically stable up to at least 500 [degrees]C, allowing post-transfer wafer processing. Index Terms--Heterogeneous device integration, probe-based storage device, system on chip (SOC), vertical high-density interconnect, wafer-scale 3-D integration.

Ultrahigh storage areal densities can be achieved by using thermomechanical local-probe techniques to write, read back, and erase data in the form of nanometer-scale indentations in thin polymer films. This paper presents single-probe experimental results in which large data sets were recorded at 641 Gbit/[in.sup.2] and read back with raw bit-error rates better than [10.sup.-4]. (d, k) modulation coding is used to mitigate the effect of partial erasing, occurring when subsequent indentations are spaced too closely together, and to increase the effective areal density. The physical indentation profile, the sensitivity of the probe in readback mode, and noise sources that affect data detection are also discussed. Quantitative measurements of the partial erasing effect in both the on-track and cross-track directions are reported. Index Terms--Areal density experiments, probe storage, thermomechanical recording.

Ultrahigh storage densities of up to 1 Tb/[in.sup.2] or more can be achieved by using local-probe techniques to write, read back, and erase data in very thin polymer films. The thermomechanical scanning-probe-based data-storage concept called Millipede combines ultrahigh density, small form factor, and high data rate. After illustrating the principles of operation of the Millipede, a channel model for the analysis of the readback process is introduced, and analytical results are compared with experimental data. Furthermore, the arrangement of data-storage fields as well as dedicated fields for servo and timing control is discussed, and system aspects related to the readback process, multiplexing, synchronization, and position-error-signal generation for tracking are introduced. Finally, the application of (d, k) modulation coding as a means to further increase areal density is presented, and the effect on the user data rates discussed. Index Terms--Atomic force microscope, high-density data-storage system, MEMS, modulation coding, probe storage, servo control, thermomechanicai write/read/erase, timing recovery.

An integrated position sensor for a dual-axis electromagnetic tilting mirror is presented. This tilting mirror is composed of a silicon based mirror directly assembled on a silicon membrane supported by flexible beams. The position sensors are constituted by 4 Wheatstone bridges of piezoresistors which are fabricated by doping locally the flexible beams. A permanent magnet is attached to the membrane and the scanner is mounted above planar coils deposited on a ceramic substrate to achieve electromagnetic actuation. The performances of the piezoresistive sensors are evaluated by measuring the output signal of the piezoresistors as a function of the tilt of the mirror and the temperature. White light interferometry was performed for all measurement to measure the exact tilt angle. The minimum detectable angle with such sensors was 30μrad (around 13bits) in the range of the minimum resolution of the interferometer. The tilt reproducibility was 0.0186%, obtained by measuring the tilt after repeated actuations with a coil current of 50mA during 30 min and the stability over time was 0.05% in 1h without actuation. The maximum measured tilt angle was 6° (mechanical) limited by nonlinearity of the MEMS system.

In thermomechanical data writing, a resistively-heated atomic force microscope (AFM) cantilever tip forms indentations in a thin polymer film. The same cantilever operates as a thermal proximity sensor to detect the presence of previously written data bits. This paper uses recent progress in thermal analysis of the writing and reading modes to develop new cantilever designs for increased speed, sensitivity, and reduced power consumption in both writing and reading operation. Measurements of cantilever electrical resistance during heating reveals physical limits of cantilever writing and reading, and verifies a finite-difference thermal and electrical simulation of cantilever operation. This work proposes two new cantilever designs that correspond to fabrication technology benchmarks. Simulations predict that the proposed cantilevers have a higher data rate and are more sensitive than the present cantilever. The various cantilever designs offer single-bit writing times of 0.2 [micro]s-25 [micro]s for driving voltages of 2-25 V. The thermal reading [DELTA]R/R sensitivity is as high as 4 x [10.sup.-4] per vertical nm in near steady-state operation. Analysis of the adaptable operation of a single cantilever bounds the operation of a cantilever array. The present cantilever operates with an array data rate as high as 35 Mbit [sec.sup.-1] at a power of 330 mW and can operate at less than 100 mW. Proposed cantilevers offer a factor of 10 improvements in both data rate and power consumption. By considering their thermal, mechanical and electrical design, and by optimizing cantilevers for both writing and reading, this work aims to guide the future development of AFM cantilevers for thermomechanical data storage systems. [774] Index Terms--Atomic force microscope (AFM), data storage, microscale heat transfer, thermal engineering.

The torquemeters designed as piezoresistive silicon cantilevers were developed to detect torque and work either in flexion or torsion mode. The design of the cantilevers utilized a standard two-leg flexion offering simplicity, sturdiness and increased sensitivity. The alternative version of the cantilever contained an extra central leg appended to support the metallic paths leading to the calibration loop. The microfabrication of the piezoresistive sensors involved alignment, ion implantation and annealing processes. The applications of the cantilevers are useful in magnetometry.