International Semiconductor Conference (CAS) 2018

Article REALISIERUNG EINES LASER-VIBROMETERSYSTEMS ZUR BERÜHRUNGSLOSEN IN VIVO BESTIMMUNG DES INTRAOKULARDRUCKS was published on January 1, 2001 in the journal Biomedical Engineering / Biomedizinische Technik (volume 46, issue s1).

Submillimeter common user bolometer array (SCUBA)-2 is a wide field sub-mm bolometer camera designed to replace the existing SCUBA instrument on the JCMT in Hawaii. It will be many hundreds of times faster in large area mapping than SCUBA and will also go deeper in a single frame. It will enable the many discoveries of SCUBA to be followed up with deep systematic surveys and help act as a pathfinder for the ALMA interferometer. The key technologies for making the arrays have been demonstrated and will be put together to fabricate the first prototype later this year (2003). The wide field nature of the SCUBA-2 bolometer camera, combined with the diffraction limit at sub-mm wavelengths, leads to physically large focal planes where the issues of stray light control, magnetic shielding, and electrical, thermal and mechanical connection must be carefully addressed in order to realise a successful instrument. We describe the solutions we have adopted for these problem areas.

We describe the techniques used to fabricate SCUBA-2, the first large-format, filled array of bolometers for sub-millimeter astronomy. With two monolithic arrays of ∼10,000 bolometers, SCUBA-2 is made possible by a unique combination of advanced technologies. The detectors are made from thermally bonded and thinned silicon wafers whose surface is ion-implanted to match the impedance of free space. SCUBA-2s pixels are suspended on a View the MathML source silicon nitride membrane with low tensile stress. Deep-etch micromachining to View the MathML source by the Bosch process isolates each pixel thermally. Proximity effect transition edge sensors formed from Mo/Cu bilayers (Nucl. Instr. and Meth. A, these proceedings) are the temperature sensing elements for the bolometers. To read out such a large number of pixels, SCUBA-2 uses a superconducting quantum interference device readout for time domain multiplexing (Nucl. Instr. and Meth. A, these proceedings). The detector wafer is flip-chip bonded to the multiplexer wafer by indium bumps which provide electrical and thermal connections. The technologies that make SCUBA-2 possible have applications for large-format arrays from the submillimeter through the X-ray spectral regions.

SCUBA-2 is a second generation, wide-field submillimeter camera under development for the James Clerk Maxwell Telescope. With over 12,000 pixels, in two arrays, SCUBA-2 will map the submillimeter sky ~1000 times faster than the current SCUBA instrument to the same signal-to-noise. Many areas of astronomy will benefit from such a highly sensitive survey instrument: from studies of galaxy formation and evolution in the early Universe to understanding star and planet formation in our own Galaxy. Due to be operational in 2006, SCUBA-2 will also act as a "pathfinder" for the new generation of submillimeter interferometers (such as ALMA) by performing large-area surveys to an unprecedented depth. The challenge of developing the detectors and multiplexer is discussed in this paper.

Article VERFAHREN ZUR SCHWINGUNGSANREGUNG DES AUGES FÜR DIE BERÜHRUNGSLOSE TONOMETRIE was published on January 1, 2002 in the journal Biomedical Engineering / Biomedizinische Technik (volume 47, issue s1a).

We outline the need for SCUBA 2, its goals and specifications. We give reasons for the choice of the low temperature detector technology of TES arrays and SQUID multiplexers, and describe our pixel and array architecture and progress on the project to date.

To allow measurements of the intraocular pressure (IOP) by glaucoma patients themselves (self-tonometry) a handheld-interferometer system for non-contact in vivo measurements of microvibrations of the human eye was realized. The measurement principle is based on the dependence of the resonance frequencies of the human eye on the IOP. To analyze this, the human eye is stimulated by ultrasonic waves and the induced microvibrations are measured with a vibrometer and processed by a DSP unit. Beside a stabilized diode laser and a low noise photodetector an exact three-dimensional positioning system had to be developed to guarantee reliable measurements. To investigate the corresponding requirements a camera-based system for the detection of human eye movements was developed and test series with several persons were made. Based on these results an adjustment unit was integrated in a miniaturized interferometer system: After a short self-adjusting procedure lateral to the setup by overlaying two targets of a highly sensitive optical system the correct measuring distance between the cornea and the vibrometer parallel to the optical axis is determined automatically by an astigmatic auto-focus system. With this handheld-vibrometer in vivo measurements with several test persons were made with very good results concerning the reliability and handling capability.

Direct bonding of two mirror-polished wafers, without any external applied energy and at low temperature, is an attractive technique for the new generation of ICs, due to the flexibility that the technique offers. This technique can be used for advanced CMOS applications and for MEMS ones, that are MOS compatible. The bonded structure can be obtained using wet or dry activation techniques. The aim of the paper is to provide a method that assures pairs of bonded wafers in case of using a normal thick wafer (/spl sim/300 /spl mu/m) and a thin one (less than 100 /spl mu/m).

This paper describes a new method to examine the intraocular pressure (IOP) without any contact with the eye. In our new approach the IOP is determined indirectly from the acoustic properties of the eye, as the resonance frequencies of the bulbus are shifting with increasing IOP, In a first step simulations were made with the Finite Element Method to explore the correlation between the IOP and the acoustic properties of the bulbus, The results showed a significant rise of the resonance frequencies with increasing IOP. Simultaneously a in-vitro measurement system was build comprising a modified michelson interferometer to measure the vibrations, a transducer to stimulate the eye and a controlling PC. With this system measurements were made with artificial eyes and enucleated pig eyes to prove the correlation experimentally. The eyes were stimulated both contacting the eye with a transducer by a stick and contactless with sonic waves. Several series of measurements showed a proportional constant of 1,25 Hz/mmHg in average, which can be detected easily. The standard deviation measuring different pig eyes was 4,5 mmHg. Next a in-vivo system was developed to study the acoustic behaviour of the human eye in the real environment. The in-vivo system consists of a miniaturised semiconductor-laser interferometer complying laser safety requirements, an automatic positioning unit and an excitation unit to stimulate vibrations of the eye. Sub-micrometer vibrations of the eye can be measured in-vivo with this system.

Liquid crystal over silicon (LCoS) is an established technology for reflective spatial light modulators (SLM's) and microdisplays. While most of the manufacturing methods used are mature, there exist a number of unresolved issues associated with the mass production of high quality devices. Existing manufacturing technology leaves the final mirror elements raised from the surface of the surrounding dielectric causing problems with the filling of the liquid crystal (LC). The flow front during filling is influential on the final alignment qualities, so it is essential that this flow front follows the ideal linear shape.We report on a method to remove this mirror step height by the use of an aluminium dual damascene technique. This process produces mirrors which are embedded within the dielectric insulating layer thereby removing most of the LC flow front aberrations, caused by the surface topography, during LC filling. We discuss the novel methods developed to overcome the damascene induced problems of dishing and erosion. The results will be discussed with particular bias towards their use in the manufacture of reflective micro-displays.

This paper describes a new method to examine the intraocular pressure (IOP) without any contact to the eye. In our new approach the IOP is determined indirectly from the acoustic properties of the eye as the resonance frequencies of the bulbus are shifting with increasing IOP. Simulations with the Finite Element Method were done to explore the coherence between the IOP and the acoustic properties of the bulbus. A three-dimensional model of the eye was developed comprising the elastic cornea and sclera and the vitreous body. The results showed a significant rise of the resonance-frequencies with increasing IOP. This shift is enlarging for higher modes. In parallel measurements were performed on artificial eyes and on enucleated pig eyes to prove this correlation experimentally. A measuring system existing of a transducer to excite the bulbus, a miniaturized laser-vibrometer and PC was built. The eyes were stimulated both contacting the eye with a transducer by a stick and contactless with sonic waves. Several series of measurements were done to examine the pressure dependency of the acoustic behavior. The measurements showed a proportional constant of 1.25 Hz/mmHg in average, which can be detected easily. The standard deviation measuring different pig eyes was 4.5 mmHg.

We describe the first set of chips to be designed and manufactured with the specific objective of use in an education environment. The chips are the result of a collaboration between educators and industry and introduce students to complex microelectronics technology by presenting simple building blocks fabricated using standard semiconductor manufacturing techniques. Current usage indicates that the chips are a valuable resource in microelectronics education.

The temperature dependence of the conductivity in uniaxially stressed Si(100) metal-oxide-semiconductor field effect transistor inversion layers in the weakly localised regime has been measured for temperatures from 1.2K to 4.2K. The results show a strong linear increase in conductivity with decreasing temperature. The application of uniaxial stress is shown to increase or decrease the percentage change in conductivity over the temperature range depending on the initial Fermi level at zero stress.

The transverse conductivity sigma xx' of uniaxially stressed Si(100) inversion layers has been measured at T=0.36 K. The initial application of uniaxial stress leads to an increase in valley splitting and a reduction of conductivity maxima. At high stresses, on the other hand, conductivity peaks were observed to increase and to merge with increasing stress. At intermediate stresses, the conductivity peak movements can be explained by assuming the presence of a subband-subband electron exchange interaction.

Piezoresistance measurements have been obtained on narrow polycrystalline-silicon-gated silicon field-effect transistors. From the anomalous structure observed on the piezoresistance traces it has been deduced that large compressive intrinsic edge stresses are present in these devices. These are estimated from the experimental data to be approximately 180 N mm-2, in reasonable agreement with a theoretical calculation based on a model proposed to explain the presence of such large stresses.

Measurements of the Hall (ρxy) and transverse (ρxx) resistivities in narrow polycrystalline silicon-gated Si(100) field-effect transistors have been obtained. The measurements were carried out both with and without externally applied uniaxial stress. Analysis of the results suggests the presence of large compressive intrinsic edge stresses. A model based on device fabrication is developed to explain the presence of these edge stresses.