The black silicon method: a universal method for determining the parameter setting of a fluorine-based reactive ion etcher in deep silicon trench etching with profile control

Very deep trenches (up to 200 µm) with high aspect ratios (up to 10) in silicon and polymers are etched using a fluorine-based plasma (SF6/O2/CHF3). Isotropic, positively and negatively (i.e. reverse) tapered as well as fully vertical walls with smooth surfaces are achieved by controlling the plasma chemistry. A convenient way to find the processing conditions needed for a vertical wall is described: the black silicon method. This new procedure is checked for three different reactive ion etchers (RIE), two parallel-plate reactors and a hexode. The influence of the RF power, pressure and gas mixture on the profile will be shown. Scanning electron microscope (SEM) photos are included to demonstrate the black silicon method, the influence of the gases on the profile, and the use of this method in fabricating microelectromechanical systems (MEMS)

Highly sensitive micro coriolis mass flow sensor

We have realized a micromachined micro Coriolis mass flow sensor consisting of a silicon nitride resonant tube of 40 ?m diameter and 1.2 μm wall thickness. Actuation of the sensor in resonance mode is achieved by Lorentz forces. First measurements with both gas and liquid flow have demonstrated a resolution in the order of 10 milligram per hour. The sensor can simultaneously be used as a density sensor

A versatile technology platform for microfluidic handling systems, part I:fabrication and functionalization

Many microfluidic devices are made using specialized fabrication processes, limiting the ability to integrate those devices on the same chip. In this paper, a versatile technology platform is presented that allows for integration of many different devices. It provides a method to design channels in a wide range of sizes and shapes with different functionalization options in close proximity to the fluid in the channels. The latter includes release of the channels for thermal isolation or mechanical movement and metal or piezoelectric layers for actuation and read-out. The channel walls are made using silicon-rich silicon nitride to provide durable, strong, chemically inert and thermally stable channels directly below the substrate surface

Rotational precision MEMS-based clamping mechanism for stable fixation of elastic mechanisms

Conventional TEM sample manipulators often lack the crucial stability of 0.1 nm/min. A MEMS manipulator attached directly to the TEM pole would greatly increase both thermal and dynamic stability. However a stable E-beam requires no interference of electric or magnetic fields. Therefore the manipulator should be stably fixed without power. To this end a mechanical clamp is presented which clamps one of the actuators of the TEM sample manipulator (Figure 2). The clamp incorporates a relatively large clamp force of 0.5 mN with respect to the device area and is able to maintain the clamp force without external power. In previous work [1] a theoretical basis has been presented of an earlier clamp version. In this paper a rotational clamp which has been made and tested is presented. This clamp design is part of a research project for a 6 Degree of Freedom MEMS TEM sample manipulator. \u

Nanometer range closed-loop control of a stepper micro-motor for data storage

We present a nanometer range, closed-loop control study for MEMS stepper actuators. Although generically applicable to other types of stepper motors, the control design presented here was particularly intended for one dimensional shuffle actuators fabricated by surface micromachining technology. The stepper actuator features 50 nm or smaller step sizes. It can deliver forces up to 5 mN (measured) and has a typical range of about 20 μm. The target application is probe storage, where positioning accuracies of about 10 nm are required. The presence of inherent actuator stiction, load disturbances, and other effects make physical modeling and control studies necessary. Performed experiments include measurements with openand closed-loop control, where a positioning accuracy in the order of tens of nm or better is obtained from image data of a conventional fire-wire camera at 30 fps

Ambient temperature-gradient compensated low-drift thermopile flow sensor

A highly-sensitive thermal flow sensor for liquid flow with nl-min-1 resolution has been realised. The sensor consists of freely-suspended silicon-rich silicon-nitride microchannels with integrated Al heater resistors and Al/poly-Si++ thermopiles. The influence of drift in the thin-film metal resistors is effectively eliminated by using thermopiles combined with an adequate measurement method, where the power in the heater resistors is controlled, e.g. constant-power calorimetric method or temperature balancing method. The special meandering layout of the microchannels and the placement of thermopile junctions increases sensitivity by summing the thermopile voltages due to convection by fluid flow, whereas the influence of ambient temperature gradients is compensated for

Wafer-through access trenches for surface channel technology

A new method to integrate fluidic access to devices made by surface channel technology is proposed. The method uses a high aspect-ratio DRIE process for etching wafer through trenches to allow access to the front side of the surface channel device. LPCVD of TEOS is used as etch-stop and to define a reliable connection between channel and access trench during fabrication. The resulting connection is robust and increases design freedom for the surface channel technology. The complete fluid path has only one wetting material