No abstract

Semiconductor wafer bonding has increasingly become a technology of choice for materials integration in microelectronics, optoelectronics, and microelectromechanical systems. The present overview concentrates on some basic issues associated with wafer bonding such as the reactions at the bonding interface during hydrophobic and hydrophilic wafer bonding, as well as during ultrahigh vacuum bonding. Mechanisms of hydrogen-implantation induced layer splitting ͑''smart-cut'' and ''smarter-cut'' approaches͒ are also considered. Finally, recent developments in the area of so-called ''compliant universal substrates'' based on twist wafer bonding are discussed.

Compounds of the general formula M(SR)2 (M = Zn, Cd; R = i-Pr, t-Bu, Bz) have been prepared and explored as potential unimolecular starting materials for the preparation of binary group 12 metal sulfides. These new compounds have been characterized by IR spectroscopy and thermogravimetric analysis. Chemical derivatization of these insoluble metal-bis(thiolate) compounds by complexation with N-CH3 -imidazole renders them more soluble. These adducts were investigated by elemental analysis. Thermolytic decompositions of both the parent and derivatized compounds have been carried out both in the solid state and by heating a suspension of the appropriate metal-bis(thiolate) compound in an inert high boiling hydrocarbon medium. The thermolysis products have been studied by GC/MS (liquids) and x-ray powder diffraction (XRPD), scanning electron microscopy (SEM), and particle size determination (solids).

In microsystems technologies, frequently complex structures consisting of structured or plain silicon or other wafers have to be joined to one mechanically stable configuration. In many cases, wafer bonding, also termed fusion bonding, allows to achieve this objective. The present overview will introduce the different requirements surfaces have to fulfill for successful bonding especially in the case of silicon wafers. Special emphasis is put on understanding the atomistic reactions at the bonding interface. This understanding has allowed the development of a simple low temperature bonding approach which allows to reach high bonding energies at temperatures as low as 1508C. Implications for pressure sensors will be discussed as well as various thinning approaches and bonding of dissimilar materials. q 1999 Elsevier Science S.A. All rights reserved.

The purpose of this contribution is to give an overview of silicon-on-insulator (SOI) technology with emphasis on the fabrication of SOI substrates and their material properties. Although the concept of SOI has been around for several decades, only recent material science advances made the fabrication of thin-®lm substrates possible whose material quality is comparable to bulk wafers. SIMOX wafers bene®tted from lowering the oxygen dose needed for ion-beam synthesis of buried oxide layers and optimisation of the thermal annealing cycles. Through improved thinning technologies, the wafer-direct-bonding approach for the burial of thermal oxide layers became competetive for thin-®lm SOI, especially when complemented with the salvaging of the``sacri®cial'' wafer. 7