Pulsed DC magnetron sputtered aluminum nitride (AlN) thin films are prepared on several seed layers and at different sputtering conditions. The piezoelectric c-axis (002) orientation of the AlN is analyzed with X-ray diffraction method. The transverse piezoelectric coefficient d31 is determined with a Laser-Doppler-Vibrometer at cantilevers and membranes by analytical calculations and finite element method. Additionally, thin film AlN on bulk silicon is used to characterize the longitudinal piezoelectric charge coefficient d33.

The material CoSi"2 is preferred for the fabrication of buried silicide films between silicon device layer and buried oxide of SOI substrates for BICMOS integrations. Such an application needs excellent quality of the interface between the silicide and the silicon device layer. Using the conventional cobalt salicide process the roughness and waviness of the interface is too large for a device application. In this presentation three technologies to improve the CoSi"2/Si-interface quality were characterized. Using the first technology a very thin single crystalline CoSi"2 film was fabricated on a silicon substrate. This film acts as initial layer to produce thicker single crystalline silicide films. By the second technology an interlayer between cobalt and the silicon substrate was used to mediate an epitaxial CoSi"2 growth. Different types and materials were tested. Using the third technique a sacrificial layer of polycrystalline silicon between cobalt and the silicon substrate was consumed during the silicidation reaction. This method gives the best results with interface roughness values of less than 1nm. The interface roughness was measured after CoSi"2 removal using AFM. A possible epitaxial growth of the silicide films was investigated with XRD analysis. Cross sectional SEM images were prepared to analyze the interface waviness and the CoSi"2 structure.

The fabrication of a new silicon on silicide on insulator (SSOI) substrate for the integration of bipolar and CMOS devices on the same wafer is demonstrated. This structure includes a 500nm thick buried oxide (BOX) and a 90nm patterned cobalt disilicide film under a 300nm thick silicon device layer. Two different process flows were used to build the final SSOI substrate. The first process bases on the known BESOI regime and includes wafer grinding and polishing steps. The second technology is a modified variant of the SmartCutTM method, where the SOI substrates are formed using hydrogen implantation, wafer splitting and CMP polishing. The cobalt disilicide was produced using a conventional cobalt salicide process. This process consists of cobalt deposition, two RTA steps and a selective etch. Some modifications in the salicide regime were made to improve the interface between the CoSi2 and the device silicon.

A silicon-on-metal-on-insulator substrate, consisting of a top Si layer, a buried COSi2 layer and a buried SiO2 layer on a Si (100) substrate was formed using Co silicidation, wafer bonding and wafer splitting. It is shown that the buried silicide layers in this structure exhibit a much higher thermal stability than surface layers. Resistivity measurements and cross-sectional transmission electron microscopy investigations revealed that buried COSi2 layers withstand furnace anneals at 1000 degrees C up to 2 h, while surface COSi2 layers started to degrade after 10 min anneals at 1000 degrees C. The proposed substrate is most useful for BiCMOS applications.

This contribution deals with design, fabrication and test of a micromachined resonant scanner usable for horizontal deflection of the laser beam in a projection display. The electrostatically driven plate is separated from the mirror in order to reduce air damping and electrostatic non linearity. The device consists of a circularly shaped mirror which is suspended by torsion beams in the center of an elastically suspended driving plate. A resonator with two rotational degrees of freedom is arranged in this way. The rotation axes of mirror and driving plate are the same. A suitable design of the properties of the two degrees of freedom resonator leads to a significant amplification of the oscillation of the mirror compared to the oscillation of the driving plate. The first resonant mode is a rotation of both plates with nearly the same magnitude at a frequency of approx. 5 kHz. The second mode with paraphase deflection at 24 kHz shows a deflection amplification by a ratio of 53 and is used for scanning operation. A supporting part made of glass carries two electrodes in the region of the driving plate and has a micro sandblasted hole beneath the mirror. Bulk micromachining, KOH wet etching of the electrode gap size on the back side of the driving plate, reactive ion etching for contour shaping of the mirror, of the driving plate and of the torsion beams and anodic bonding have been used for fabrication of the mechanical structure. The mirror is evaporated by an aluminum layer. Applying a voltage of 380V results in a mechanical deflection of +/- 5.5 degrees at 24 kHz at atmosphere pressure. The device shows very small dynamic warp (< 100nm) of the mirror plate even though the relatively large size of 2.2 mm diameter because of the thickness of 280 mu m. The measured mechanical Q-factor is 5100.

Laser-trimming of microstructures is a promising approach to overcome manufacturing tolerances and to tune sensors and actuators for certain operating conditions. A joint research project between 3D-Macromac AG and the Chemnitz Center for Microtechnologies investigates new technologies for wafer level stiffness and frequency tuning of silicon microstructures by ultra short laser pulse tuning. Goal of the development work is to establish a novel technology which allows for in-line measurement of mechanical properties and laser treatment in order to calibrate performance parameter of MEMS. Particular features of laser trimming will be demonstrated on Micro Mirror Devices (MMDs) which are widely used for image projection applications Fig. 1.

The successful fabrication of a silicon on metal on insulator (SOMI) substrate with a structured buried silicide layer for BICMOS applications is shown in this paper. The cobalt silicide is used as the buried silicide layer in the SOMI substrate because of its high thermal stability, low resistivity and easier fabrication process. Conventional cobalt salicide process was used to form CoSi2 structures. The SOMI substrate was fabricated on the wafer level using wafer bonding, CMP and back grinding technologies. A SOMI substrate, consisting of a 300 nm thick top-Si, a buried thin CoSi2 layer, a buried SiO2 layer on a silicon substrate, was formed using an SOI substrate as the starting material. The buried silicide layer has a resistivity of 16.3 μΩ cm and shows a high thermal stability which is sufficient for device applications.

Although the color reproduction of RGB-based image capturing systems is sufficient for many tasks, there are some critical color matching applications like digitizing of high quality illustrated books, artwork imaging or catalogue selling. Due to the known theoretical limitations of RGB-techniques, multi-channel methods of image capture have been introduced in the recent years, typically based on a multitude of color filters. In this paper a spectral imaging system is presented where the color information of an original image is separated by a diffraction grating. The grating is applied on a micro mirror, which is actuated by an electrostatic field causing a high frequency oscillation of the device. Due to the vibration different spectral intervals of the diffracted light can be detected by a CCD-line. As a first step 35 different spectral intervals of each pixel are measured. The gamut of the resulting color space compared to standard RGB-based image capturing systems is shown. Finally, experimental results are discussed dealing with the limits of resolution of this micro mirror based multispectral device.

Thin films of Cu(6N), CuAl0.3wt% and CuCr0.17wt% with or without a Ta seed or toplayer were deposited by sputtering at room temparature and at 225 degreesC and afterwards annealed. The resistivity for the different thermal treatments reflects the behavior predicted by the phase diagrams. Al stays soluted in the Cu crystal, while Cr atoms diffuse out of the Cu lattice at higher temperatures. XRD failed in detecting precipitated Cr. The addition of Cr or Al changes the microstructure to a more uniform grain size distribution with smaller grains. Modified stress relaxation and roughness can be discussed in terms of a suppressed bulk diffusion,. The influence of the solute atoms on relaxed film stress is neglible. A polycrystalline Ta seed layer improves the <111> orientation and also increases the film stress for all three materials.

Waferbonding technologies were used for the fabrication and mounting of micromechanical devices in bulk micromachining. Special high and low temperature bond processes and their integration into the technological process flow were introduced during the fabrication of gyroscopes and micromirrors. Detailed investigations show to which extent the bonding processes were able to fulfil general requirements like high resistance to mechanical stress, pattering possibilities of bonded substrates and compatibility to electronic components. The results of pattern transfer in SOI-wafers during the fabrication of gyroscope resonator structures after high and low wafer bonding processes with different pre-treatments and the comparison of these results with the bond firmness of the substrates set up the priorities of our investigations. Furthermore, this paper describes the application of the best low temperature wafer bonding process for the fabrication of a mircomachined silicon mirrorarray and represents the bonding process and its requirements.

Cu and CuAl0.3 wt.% films were deposited by DC magnetron sputtering on SiO2 or a Ta interlayer. They are characterized with respect to resistivity, stress, adhesion, roughness and microstructure. The Al concentration is homogeneous within the CuAl0.3 wt.% films and equals the target composition. Al is enriched at the surface after annealing. No Al precipitation or formation of intermetallic phases is observed. The addition of Al results in a decreased roughness, which is caused by significantly smaller grains of nearly constant size. Adhesion on SiO2 (after annealing) and oxidation resistance are improved due to the addition of Al. The modified properties of the alloy are balanced with an increase in resistivity of 3.3 μΩ cm after deposition, which decreases to the bulk value of 2.6 μΩ cm after annealing. Process parameters and target erosion profile are equal to pure Cu targets.

Ta and TaNx are deposited by reactive sputtering at different substrate temperatures. A phase transition from alpha-Ta to beta-Ta is found to occur at about 320degreesC and causes a sharp drop in resistivity from 180 muOmegacm down to 19 muOmegacm. The alpha-Ta films have larger grains. Although the temperature is found to be an important parameter, its role is not clear. TaNx films were found to grow in the delta-TaN phase and partly hcp-Ta2N, depending on temperature and flow ratio. The resistivity of the TaNx films decreases for higher substrate temperature. All films exhibit compressive film stress, which is very large at the transition point from the metallic to the reactive mode. The stress does not depend on the substrate.

This contribution deals with design, fabrication and test of a micromachined gauge for vacuum pressure as well as with the related electronics. An electrostatically driven and capacitively sensed Si tuning fork is operated at the fundamental resonance frequency. The damping is used as a measure of the pressure. We use bulk micromachining with two silicon and two glass wafers for the fabrication of the sensor. Design and working principle have been optimized in order to reach high sensitivity and a transfer curve with a logarithmic characteristic in a wide range (10−3 mbar …100 mbar).

The present study is focused on the development of a gas sensor for application in a high temperature environment. The sensor has been realised using thin films prepared on silicon substrates including a high temperature stable heating and wiring system. TiO2 acts as sensitive layer. Measurements have been carried out in synthetic gas mixtures as well as in gases in a given application. Neural networks and multivariate data analysis have been used for determining the gas concentrations. The capability to detect CO, NOx, and toluene is shown.

Silver based surface reflection coatings for silicon based micro mirrors have been der eloped. A CI polymer or a double layer of AlSiN and TiO2 have been used as protective films and Ti as an adhesion layer. The optical properties of the film stacks, their chemical stability as well ar mechanical stress behavior are presented.

With the recent progress in microsystems technology there is a growing need for accurate knowledge of material properties in design. Especially on thin films, material properties are strongly affected by layer thickness and deposition parameters. Since traditional methods for the characterization of bulk materials are hardly applicable on thin films novel extraction techniques are required. The following paper deals with a resonant method to determine Young's modulus and residual stress simultaneously. Therefore an array of microbridges with variable length is etched into the layer material. Samples are stimulated electrostatically to small signal oscillations and their resonance frequency is measured by a laser doppler interferometer. Based on the theory of prestressed beams both material parameters can be separated independently by nonlinear function fitting. Accuracy of this approach will be assessed and first results are presented.

On the example of bulk-micromachined electrostatically driven micromirror arrays, the influence of partially absorbed laser power on the surface deformation by the caused temperature rise is discussed in this contribution. A maximum power rating can he estimated regarding the measurement results.