Steffen Heinz

Time Dependent Isolation Capability of High Voltage Deep Trench Isolation

The long term isolation properties of deep trenches in thick SOI have been investigated by current-voltage- characteristics. A strong change of the measured trench leakage current was observed depending on the applied voltage. Further on a marked decrease of the leakage current was observed depending on the duration and polarity of the applied stress. The improvement of the formatted trench isolation was found to be irreversible with time, temperature and voltage polarity. This so-called formation effect can be described by a theoretical simulation model assuming a tunneling process of electrons through the oxide barrier, taking into account the charging and discharging of traps within the trench sidewall oxides. The observed formation effect leads to improved reliability results, wherein the trench is either damaged at the start of the stressing or no dielectric breakdown occurs at all.

High-Voltage Amplifier Design for MEMS based Switching Arrays in Wavelength-Division Multiplexing Networks

The paper describes the design requirements of integrated high-voltage amplifiers for large MEMS based arrays which consist of electrostatically driven actuators. Such actuators are applied in optical switching arrays for cross connects in wavelength-division multiplexing (WDM) networks. Besides a new calculation approach for the efficiency of amplifier operation modes a new concept of level-shifter circuitry for switching output stages of high-voltage amplifiers is presented and compared with conventionally level-shifter circuits.

Optimization of trench manufacturing for a new high-voltage semiconductor technology

Deep trenches for device insulation in a high-voltage process in thick SOI were fabricated using different manufacturing technologies. The trenches have been investigated by current-voltage-characteristics. In comparison to the conventional produced trenches alternatively fabricated samples reach a remarkable increase of the breakdown voltages accompanied by a decline of the leakage current in the order of several magnitudes. Respecting other process parameters a trench fabrication method has been selected which enables the manufacturing of reliable single trenches suitable for operating voltages up to 650 V. The new trench can be implied within a prospective X-FAB process. A reduction of area consumption is possible in many designs by replacing double trenches by single trenches. The future high-voltage X-FAB process will include new primitive devices which are currently designed and characterized. In this work new diode types with characteristic properties are presented.

Modeling the Leakage Current of Dielectric Isolation Structures in a High-Voltage Semiconductor Technology

System-in-package integration becomes more and more important in the growing market of micromechanical sensors and actuators. The most important group of actuators are those based on the electrostatic working principle. Because of the high voltages used to drive these actuators, new methods of isolation need to be introduced. In this paper we will characterize and model the electrical behavior of such an isolation technology. A simple device model to regard parasitic effects of this isolation during the process of circuit design will be introduced.

Application of micromirror arrays for Hadamard transform optics

The paper presents a novel kind of Hadamard transform optic. First investigations are made with a micro mirror array in a Hadamard transform spectrometer (HTS) whereby the usually used detector array is replaced by the micro mirror array. All the mirrors are imaged onto a single detector. The measurement is performed using a Hadamard matrix, i.e. while each detector reading a certain combination of mirrors given by the matrix is reflecting the light towards the detector. All the rest of them are reflecting the light beside it. The consequence is an improvement of the signal to noise ratio (SNR). The novelty of the realized spectrometer is that in contrast to other applications the mirrors are not statically switched but they are forced to oscillate at their resonant frequency. By this way a special Hadamard matrix can be used that improves the SNR best.

Single trench isolation for a 650 V SOI technology with low mechanical stress

The successful optimization and characterization of a deep trench isolation in a thick SOI process for operating voltages up to 650 V is reported. Different technologies were investigated to optimize the mechanical stress during wafer processing and to increase the breakdown voltage of a single trench configuration. Comprehensive electrical characterization was done to investigate achievable operating conditions and related reliability issues for thick oxide trench isolation layers. The most promising trench technology was choosen as a modular extension to an existing 650 V SOI BCD process.

Yet another tuning fork gyroscope

This paper reports on the development of a micromechanical vibrating mass tuning fork gyroscope with coupled drive and sense modes. The mechanical structure has been designed to have a first anti-phase drive mode and a second anti-phase sense mode. The frequencies of all other modal modes are higher. The micromechanical structure is fabricated with a cavity SOI technology called BDRIE [1]. The analog ASIC for very low noise readout (<; 50 nV/rtHz) is placed on the MEMS and is connected symmetrically with wire bonds. MEMS and ASIC have been co-designed to best fit physically and electrically to each other.

Combining CMOS and MEMS technologies in a monolithic system for observing filter pollutions

The combination of CMOS and MEMS technologies in principle opens new potentials for the creation of complex, compact, reliable solutions. Within the current research work a “SmartFilter” module to observe the pollution of filters in suction and filtering systems has been developed, provided with piezoresistive pressure sensor, controller core, power management, digital and analog signal processing as well as an RFID interface to allow wireless transfer of energy and data. The system design, the RFID-frontend including an antenna, aspects of analog signal design and packaging are discussed. Basis of the innovation is the integration of a pressure sensor fabrication module into a modern 350 nm CMOS mixed-signal semiconductor technology.

The charge sensing device approach - Sensors for textile machines using the natural electrostatic charge of the yarn

This paper presents the charge sensing device approach for sensors in textile machines. A wide range of sensor application in textile machinery can use a charge sensing device for instance to detect the presence of yarn or the speed of yarn. The charge sensing device approach offers important advantages compared to the state of the art sensor principles and additional cost reducing effects can be expected. In this paper the charge sensing principle is presented and the advantages and disadvantages are discussed. Two examples of “charge sensors” in prototyping and preliminary state for textile machine application are demonstrated.