Silicon nitride fabricated

Figure 8.18 Microstructure of the silicon nitride fabricated through dispersing 3 wt% of P-seed crystals into the raw powder slurry of a-phase and Lu203-Si02 sintering additives and subsequent tape-casting, (a) Plane parallel...

Hsieh et al. (1997) employed microelectromechanical system (MEMS) technologies to develop a miniature ECM using polymer electret as show in Fig. 7. The diaphragm is 0.91 pm LPCVD silicon nitride fabricated through backside anisotropic wet etching of <100> silicon substrate. Teflon AF is spun on with the thickness of 1.2 pm over the nitride membrane and is used as the electret layer. After charging, the silicon chip with the diaphragm is bonded to the other silicon chip with a photoresist spacer. 

While the manifolds were fabricated by a plain molding process, the microchannels substrate fabrication was quite complicated and was achieved by a multistage process. The following main stages were used in the process (1) double side oxidation of a 525 pm (1 0 0) silicon substrate to 1,000 A, (2) single side 1,200 A silicon nitride deposition, (3) silicon nitride channels template opening by reactive... 

Thin films of electrical insulators are essential elements in the design and fabrication of electronic components. The most widely used insulator materials (dielectrics) are silicon oxide (Si02) and silicon nitride (Si3N4). These materials are extensively produced by CVD. 

A cross-sectional schematic of a monolithic gas sensor system featuring a microhotplate is shown in Fig. 2.2. Its fabrication relies on an industrial CMOS-process with subsequent micromachining steps. Diverse thin-film layers, which can be used for electrical insulation and passivation, are available in the CMOS-process. They are denoted dielectric layers and include several silicon-oxide layers such as the thermal field oxide, the contact oxide and the intermetal oxide as well as a silicon-nitride layer that serves as passivation. All these materials exhibit a characteristically low thermal conductivity, so that a membrane, which consists of only the dielectric layers, provides excellent thermal insulation between the bulk-silicon chip and a heated area. The heated area features a resistive heater, a temperature sensor, and the electrodes that contact the deposited sensitive metal oxide. An additional temperature sensor is integrated close to the circuitry on the bulk chip to monitor the overall chip temperature. The membrane is released by etching away the silicon underneath the dielectric layers. Depending on the micromachining procedure, it is possible to leave a silicon island underneath the heated area. Such an island can serve as a heat spreader and also mechanically stabihzes the membrane. The fabrication process will be explained in more detail in Chap 4. 

Progress in the design and fabrication of high-quality optical microresonators is closely related to the development of novel optical materials and technologies. The key material systems used for microresonator fabrication include silica, silica on silicon, silicon, silicon on insulator, silicon nitride and oxynitride, polymers, semiconductors such as GaAs, InP, GalnAsP, GaN, etc, and crystalline materials such as lithium niobate and calcium fluoride. Table 2 smnmarises the optical characteristics of these materials (see Eldada, 2000, 2001 Hillmer, 2003 Poulsen, 2003 for more detail). 

The steam reformer is a serpentine channel with a channel width of 1000 fim and depth of 230 fim (Figure 15). Four reformers were fabricated per single 100 mm silicon wafer polished on both sides. In the procedure employed to fabricate the reactors, plasma enhanced chemical vapor deposition (PECVD) was used to deposit silicon nitride, an etch stop for a silicon wet etch later in the process, on both sides of the wafer. Next, the desired pattern was transferred to the back of the wafer using photolithography, and the silicon nitride was plasma etched. Potassium hydroxide was then used to etch the exposed silicon to the desired depth. Copper, approximately 33 nm thick, which was used as the reforming catalyst, was then deposited by sputter deposition. The reactor inlet was made by etching a 1 mm hole into the end... 

Fig. 15.2. Fabrication of silicon nitride microcantilevers with integrated tips, (a) A...

Siaions consist of three-dimensional arrays of (Si—Al) (O.N)4 tetrahe-dra. These oxynitrides are traditionally fabricated with silicon nitride An example is beta-sialon, where the O and Si are partially replaced by N and Al, respectively. Advanced sialons are now being researched to enhance fracture toughness and iinpioved cieep properties,... 

Emoto H, Hirotsuri H (1999) Microstructure Control of Silicon Nitride Ceramics Fabricated from a Powder Containing Fine /(-Nuclei. In Niihara K, Sekino T, Yasuda E, Sasa T (eds) The Science of Engineering Ceramics II Key Eng Mat 161-163. Trans Tech Publications, Switzerland, p 209... 

---