Davey D. L. Wijngaards

Infrared micro-spectrometer based on a diffraction grating

The optical properties of crystalline silicon in the IR spectral range have been used for the realisation of a grating type micro-spectrometer. An aluminium metallisation on a double side polished silicon wafer is used for fabrication of the multi-slit gratings. The dispersed spectrum propagates through this silicon wafer and is projected on an array of polysilicon thermopiles, integrated in a second bulk micromachined silicon wafer. The two wafers are bonded at low temperature. An IR spectrometer results, which is simple to fabricate and remains compatible with standard IC processing.

Design and fabrication of on-chip integrated polySiGe and polySi Peltier devices

Abstract On-chip integration of Peltier devices introduces a number of new fabrication considerations and yields a device with increasingly complex operating characteristics, when compared to the discrete device. Due to fabrication compatibility, polycrystalline SiGe (polySiGe) and polycrystalline Si (polySi) are the thermoelectric materials of choice. Device performance is compared for different thermoelectric materials, and the impact of the non-idealities on performance is analysed, interpreting the results in a graphical manner. The primary conclusion from this study is that, although often ignored, the contact resistance of the device is the most prominent non-ideality. Using a fully compatible process, various Peltier devices have been fabricated. The initial values from the measurements performed on both polySi and polySiGe correspond well to those found in literature, validating the design concept, although further optimisation is required.

Silicon ic process compatible thin metal film post-processing module

Abstract A thin metal film post-processing module, compatible with standard IC processing, is presented. The module is based on lift-off technique and enables integration of thin metal film structures with standard microelectronic processing. A wide range of metals can be used and the technique is intended for fabrication of integrated thin metal film transducers. Typical for the module are the flexibility of metal used, the flexibility of deposition order and the low temperature at which deposition takes place. As the thermal budget of the electronics remains unaffected and the standard IC process remains intact, full compatibility is assured. Application of the module is demonstrated by fabrication of low temperature coefficient of resistance (low-TCR) NiCr resistors (minimum width 1 μm, thickness 35–75 nm, resistivity 120 μΩ cm and TCR 40 × 10 −6 K −1 ) and Pt/Ti resistors for on-chip local temperature measurement (Pt/Ti 80 nm/20 nm, matching Pt-100 within 2.5%).

Study of IC compatible on-chip thermoelectric coolers

A thin-film-based thermoelectric micro-cooler has been studied and realized using the standard integrated circuit (IC) fabrication technology and bulk micromachining technology in sequence. The whole fabrication process is kept IC compatible by postponing potassium hydroxide (KOH) etching step to the last part of the fabrication sequence. Considering the fabrication compatibility, polycrystalline silicon germanium (polySiGe) is chosen as thermoelectric material even though bismuth telluride (Bi2Te3) is one of the most effective thermoelectric materials. The influence of non-idealities on device performance, such as Joule heating due to contact resistance and parasitic heat loss through supporting membrane, is analyzed. The characterized thermoelectric, thermal and electric properties of the fabricated polySiGe thermoelectric material correspond well to those from literatures. Measured cooling performance demonstrates that an on-chip micro-cooler can be applied for thermal stabilization near ambient temperature.

IC fabrication-compatible processing for instrumentation and measurement applications

The solid-state sensor field is maturing and an increasing number of applications is being served. Nevertheless, the available infrastructure and technology have found only few applications within the field of instrumentation and measurement (IM (2) to provide a representative overview of what different silicon sensor processing techniques are available; and (3) to point out their potential for use in metrological applications. To this end, a number of examples of (potentially) successful micromachined devices for metrology are discussed. The key considerations in this application area are: (1) the mechanical material properties of silicon and (2) the on-chip cointegration of the entire reference system.

Study on temperature stability improvement of on-chip reference elements using integrated Peltier coolers

On-chip integrated Peltier coolers have potential for the thermal control and stabilisation of highly localised sections of a silicon integrated circuit, at a minimum possible temperature. In an on-chip reference this ensures improved stability, without reducing basic device operation. This paper emphasises the experimental characterisation and, in a later stage, validation thereof. Initial results show a figure-of-merit of 0.26/spl middot/10/sup -3/ K/sup -1/, while a temperature drop of 2.1 K can be established.

Temperature stability improvement of on-chip reference elements using integrated Peltier coolers

On-chip integrated Peltier coolers have potential for the thermal control and stabilisation of highly localised sections of a silicon integrated circuit, at a minimum possible temperature. In an on-chip reference this ensures improved stability, without reducing basic device operation. This paper emphasises the experimental characterisation and, in a later stage, validation thereof. Initial results show a figure-of-merit of 0.26/spl middot/10/sup -3/ K/sup -1/, while a temperature drop of 2.1 K can be established.

Thermophysical Characterisation of PolySi 0.7 Ge 0.3 for Use in Thermoelectric Devices

Polycrystalline silicon germanium (polySiGe) provides a good balance between thermoelectric performance and fabrication compatibility, making it highly suitable for use in integrated Peltier elements. Unfortunately, the performance of integrated Peltier elements does not only depend on the properties of polySiGe, but also on other properties like contact resistance and thermal conduction through supporting layers. Although the primary intent of this paper is to present the first of the thermophysical properties of polySiGe, the other properties required to determine the performance of polySiGe Peltier elements are also addressed.

Study on the Behaviour of Various Substrate Geometries for Use As Passive Heat Sink

Performance of many high-accuracy (electronic) applications is reduced by thermal fluctuations within the application. The simplest and most common technique to reduce those effects is compensation, e.g. by dynamic element matching [1]. Although such techniques can significantly reduce the effect of fluctuations, they do not remove the error source, which is still preferable from a viewpoint of metrology.

Fabrication and Optical Measurements of Multi-slit Grating Based Infrared micro-spectrometer

Multi-slit diffraction grating based integrated silicon micro-spectrometers for various infrared wavelength ranges have been realised using bulk micromachining and low temperature silicon-silicon fusion bonding [1]. The transparent optical property of silicon for infrared wavelength range provides a good optical path for incident infrared light. In addition, the high reflectance of aluminium for infrared results in an efficient multi-slit type grating. The grating fabrication by a normal metal deposition with a high accuracy on a double side polished wafer makes the fabrication process simple and compatible with standard IC processing.