A monolithically integrated GMR angle sensor for automotive applications is presented. The vertical integration concept allows a combination of our spin-valve type GMR angle sensors with conventional CMOS or bipolar base technologies providing the signal conditioning. The PtMn based sensor stack exhibits an excellent thermal stability. A combination of temperature and magnetic field, however, leads to a drift of the magnetization direction of the reference system and therefore, to an increased angular error. A reduction of the net magnetic moment as well as the film thickness of the pinned and reference layer of the artificial antiferromagnet leads to a significant improvement of the robustness against thermo-magnetic stress.

In this paper, we present passive temperature compensation by means of silicon dioxide. Using an oxide refilling technique it avoids gap distance reduction and therefore prevents degradation of electromechanical coupling and motional resistance of the micro-electromechanical resonator. Samples are fabricated and electrically characterized to demonstrate the feasibility of the process concept. A constant quality factor (Q) and only a slight increase of the series resistance value (Rm) are achieved, while the frequency inaccuracy due to temperature variation is reduced. ANSYS simulations are carried out to evaluate the potential of the technique, resulting in a remaining inaccuracy of less than 40ppm.

Spin valve systems based on the giant magnetoresistive effect as used, for example, in hard disks and automotive applications consist of several functional metallic thin film layers. We have identified by secondary ion mass spectrometry two main degradation mechanisms: one is related to oxygen diffusion through a protective cap layer and the other one is interdiffusion directly at the functional layers of the giant magnetoresistive stack. By choosing a suitable material as cap layer (TaN), the oxidation effect can be suppressed.

The paper will give an introduction to the principle of the giant magneto resistive — GMR — effect and the silicon system integration of GMR sensors. The two main applications of a GMR are as a magnetic field strength sensor and as an angular field direction sensor. They will be discussed under consideration of automotive requirements.

The demand for tire pressure monitoring systems is driven by increasing comfort and safety requirements. In order to make such systems available to a wide market, cost optimized solutions are necessary. Costs can be reduced by high integration, low power consumption, small size of the module and the reduction of components by monolithically integrated and intelligent on-chip algorithms.

In this paper a silicon microphone which can be fabricated using standard semiconductor processes is presented. The acoustic-electrical transducer is based on the capacitance change of a movable 400 nm thin poly-silicon membrane with different diameters (800-1200 µm). A source follower was integrated to transform the impedance. The complete chip is 2×2×0.5 mm3 in size. The sensitivity achieved is in the range of 0.4 to 3.2 mV Pa-1.

A new silicon condenser microphone process for low stress diaphragm is presented. The diaphragm is formed either by a polysilicon layer or by a monocrystalline silicon layer of a silicon on insulator substrate (SOI). Acoustical sensitivities up to 8.2 mV/Pa with a 1×1 mm2 diaphragm for a bias voltage of only 1 V have been achieved. The A-weighted noise voltage was found to be 7 εV in the band of 100 Hz to 10 kHz.

Applications ranging from hearing aids over communication to noise cancellation open up a high volume market for low-cost, batch producible and reliable microphones. To obey these conditions, a single-chip capacitive microphone has been developed at Siemens, utilizing a modified standard CMOS process with adjacent bulk micromachining. In a first step, the microphone is integrated with a source follower, enabling low output impedance of the signal. The technology allows for the future integration of advanced circuitry. The microphone consists of an acoustically sensitive polycrystalline silicon membrane and a highly perforated back-plate as the counter electrode. To achieve highly sensitive devices, special emphasis was given to the stress of the polycrystalline silicon membrane, which should be slightly tensile. Another key issue during the fabrication and in operation is to prevent stiction of the sensitive membrane. Since the overall chip size is below 3-mm side length, surface mounting in low-cost SMD packages is possible.

The invention relates to a semiconductor detector with a base structure (4) and at least one deformable body (8), wherein the deformable body (8) consists of a semiconductor substrate which is doped with a dopant displaying a first type of conductivity. Piezo resistors (14) doped with a dopant displaying an opposite type of conductivity are located in the deformable body (8). The deformable body (8) is in contact with a medium in at least one partial area. The inventive semiconductor detector is characterized in that the partial area has a dopant concentration that is lower than the dopant concentration in the area located between said partial area and the piezo resistor (14).