Silicon nitride

About: Silicon nitride is a research topic. Over the lifetime, 32678 publications have been published within this topic receiving 413599 citations. The topic is also known as: N₄Si₃.

Principles and Applications of Wafer Curvature Techniques for Stress Measurements in Thin Films

Abstract: Measurement of the curvature induced in a wafer (or other flat plate) by the stress in a thin film has long been used as a convenient and accurate technique for the determination of the stress. Numerous improvements over the years have led to instruments that provide simple and rapid measurements of stress as a function of the time and temperature for any desired thermal history. A computer controlled instrument using laser scanning will be briefly described and its capabilities and limitations discussed. Applications of the technique to a variety of thin film materials will be discussed. In addition to the effects of differences in thermal expansion, stresses associated with various deposition techniques, gain or loss of material, phase transformations and flow will be considered. In aluminum based systems, themal expansion, plastic flow and phase transformation play major roles. Refractory metals show, in addition, large stresses associated with the deposition process. In inorganic dielectric systems thermal expansion effects are usually relatively small; deposition effects and the gain or loss of material are the dominant effects. Silica based glasses formed by chemical vapor deposition, for example, show large stress changes due to gain or loss of water, and plasma deposited silicon nitride films show large effects associated with hydrogen. Overall, determination of the stress as a function of time and temperature is a valuable part of the evaluation of a thin film material for use in a VLSI device.

Covalently Attached Organic Monolayers on SiC and SixN4 Surfaces: Formation Using UV Light at Room Temperature

Abstract: We describe the formation of alkyl monolayers on silicon carbide (SiC) and silicon-rich silicon nitride (SixN4) surfaces, using UV irradiation in the presence of alkenes. Both the surface preparation and the monolayer attachment were carried out under ambient conditions. The stable coatings obtained in this way were studied by water contact angle measurements, infrared reflection absorption spectroscopy, X-ray reflectivity, and X-ray photoelectron spectroscopy. Besides unfunctionalized 1-alkenes, methyl undec-10-enoate, and 2,2,2-trifluoroethyl undec-10-enoate were also grafted onto both substrates. The resulting ester-terminated surfaces could then be further reacted after hydrolysis using amide chemistry to easily allow the attachment of amine-containing compounds.

A MEMS Reactor for Atomic-Scale Microscopy of Nanomaterials Under Industrially Relevant Conditions

Abstract: We present a microelectromechanical systems (MEMS) nanoreactor that enables high-resolution transmission electron microscopy (TEM) (HRTEM) of nanostructured materials with atomic-scale resolution during exposure to reactive gases at 1 atm of pressure. This pressure exceeds that of existing HRTEM systems by a factor of 100, thereby entering a pressure range that is relevant to industrial purposes. The nanoreactor integrates a shallow flow channel (35 ?m high) with a microheater and with an array of electron transparent windows of silicon nitride. The windows are only 10 nm thick but are mechanically robust. The heater has the geometry of a microhotplate and is made of Pt embedded in a silicon nitride membrane. To interface the nanoreactor, a dedicated TEM specimen holder has been developed. The performance is demonstrated by the live formation of Cu nanoparticles in a catalyst for the production of methanol. At 120 kPa and for temperatures of up to 500°C , the formation of these nanoparticles can be observed clearly and with an exceptionally low thermal drift. HRTEM images of the nanoparticles show atomic lattice fringes with spacings down to 0.18 nm.

Mechanical properties of nanocomposite and multilayered Cr-Si-N sputtered thin films

Abstract: We have investigated the structural and mechanical properties of polycrystalline Cr–Si–N thin films of different morphologies. The films were deposited by reactive magnetron sputtering at 510 K using two confocal targets of Cr and Si. The structure and mechanical properties of co-deposited Cr–Si–N films depend on their silicon content. Films with silicon content lower than 3 at.% are fcc Cr 1− x Si x N compounds with a maximum hardness of 22 GPa. On the contrary, films containing more than 3 at.% of silicon show the segregation of a SiN x amorphous phase and highly columnar morphology. These samples have low hardness values (14 GPa). The alternating deposition of CrN and a-SiN x layers disrupts this columnar structure and leads to nanocomposite films. The hardness of these films varies when the multilayer period is changed, i.e. the CrN crystallite size. A maximum hardness value (26 GPa) has been found for a nanocomposite structure composed of 4 nm CrN crystallites embedded in amorphous SiN x .

Spark plasma sintering: A powerful tool to develop new silicon nitride-based materials

Abstract: Several key topics on the current assisted sintering of Si3N4-based materials are reviewed. First, different proposed mechanisms for spark plasma sintered (SPSed) ceramics are presented, discussing the electric field effect on the liquid phase behaviour and how it may influence the liquid phase sintering of Si3N4 ceramics. Next, we show that the SPS is a powerful tool to develop new Si3N4-based materials with tailored microstructures, such as functionally graded materials (FGMs) and carbon nanotubes (CNTs) containing Si3N4 matrix composites. Si3N4 FGMs are fabricated from a sole homogenous Si3N4 mixture just modifying the SPS system punches set-up, thus creating a temperature gradient through the specimen. Finally, the capability of SPS to get dense Si3N4/CNTs composites overcoming both constraint densification and nanotubes degradation is proved.