Holger Reinecke

Mechanical Characterization of Polycrystalline and Amorphous Silicon Carbide Thin Films Using Bulge Test

This paper aims at determining the mechanical parameters such as Youngs modulus, Poissons ratio, and intrinsic stress of polycrystalline and amorphous silicon carbide thin films using the bulge test. A suitable method for the bulge test of highly compressive amorphous SiC films was devised by developing tensile composite layers involving a highly tensile substrate layer. A setup suitable for use in high temperatures was developed to hold membrane chips mechanically for applying pressure. The center deflection was measured with optical interferometry. The bulge test was done on square and rectangular membranes in order to ascertain the Poissons ratio and the exact Youngs modulus of the material. The tests in this paper were conducted at room temperature. The tensile polycrystalline SiC films were obtained by low-pressure chemical vapor deposition (LPCVD) at 825°C, using monomethylsilane as the precursor. The amorphous SiC (a-SiC) films were deposited by plasma enhanced chemical vapor deposition (PECVD) process at a temperature of 870°C with silane and acetylene as precursors. Test chips were pressurized from outside the membrane cavity, and membrane deflection was measured for each pressure step. The poly-SiC layers indicated a Youngs modulus of 280 GPa with a Poissons ratio of 0.237. The Youngs modulus of a-SiC films was found to be 232 GPa, but the Poissons ratio could not be determined as we used a composite layer. A comparison with the existing literature values of Youngs modulus was also done.

Bonding mechanism in the Velcro concept Si-Si low temperature direct bonding technique

This work presents a bonding mechanism between needle-like surfaces for room temperature Si-Si direct bonding similar to the Velcro-principle, a fully CMOS compatible approach suitable for system integration using Si-motherboard concept. The proposed bonding model is superior to other presented models since it considers humidity effect and the deformation mechanism of the needles during the bonding.

Lamination of chemical incompatible optical polymer layers

The lamination process is a common method to generate polymer multilayer foils. However, the substrate materials used need to be miscible to give a stable connection. A typical set of incompatible polymers that is often used in optical applications is cyclic olefin copolymer (COC) and polymethylmethacrylate (PMMA). In this paper, we report about the development of a “Reactive Lamination Process” that is capable of forming a stable optical polymer multilayer of PMMA and COC. This paper focuses on the development of a spray coating process and the further processing with photoreactive PMMA copolymer systems that act as an unspecific primer to obtain optical polymer multilayer devices.