Thin films sacrificial

The sacrificial line method starts with deposition of the sacrificial thin film on selected... 

The details on the fabrication procedure can be found in Liu et al. [2]. In the first step, phosphosilicate glass sacrificial thin film is deposited on top of the silicon substrate. This thin film is patterned to form mesas on which... 

Various strategies are employed to prevent corrosion. The use of paint as a protective coating is described in our chapter introduction. A metal surface can also be protected by coating it with a thin film of a second metal. When the second metal is easier to oxidize than the first, the process is galvanization. Objects made of iron, including automobile bodies and steel girders, are dipped in molten zinc to provide sacrificial coatings. If a scratch penetrates the zinc film, the iron is still protected because zinc oxidizes preferentially ... 

To reduce expense, efforts are made to exploit integrated thin film technologies. For example, arrays have been produced via thin film deposition of the pyroelectric onto a sacrificial layer, e.g. a suitable metal or polysilicon, which is then selectively etched away. Thermal isolation of the pyroelectric element is achieved through engineering a gap between it and the ROIC silicon wafer. Yias in the supporting layer permit electrical connections to be made between the detector and the wafer via solder bonds. Imaging arrays have been produced in this way incorporating sputtered PST and sol-gel formed PZT films. 

For automotive applications, the various functions require several special material properties. Here, we concentrate on properties of thin films rather than on their production processes. A wide range of publications deal with sensor-specific processes, for example, silicon reactive ion etching (RIE) using the Bosch trench process [2] and sacrificial oxide etching [3, 4]. The details of standard deposition and structuring processes are described in numerous books on semiconductor technology (e.g., [5, 6]), and they are not discussed in depth here. 

Silicon oxides (SiOx) are the most widely used thin films in silicon microelectronic and micromechanical devices. Similar to silicon nitride (Section 5.5.4), these amorphous films exhibit dielectric properties. Silicon oxide is often utilized as part of a dielectric membrane, as a passivation or insulating layer, or as a sacrificial layer, which can be etched with hydrofluoric acid (HF)-containing etchants. Two different approaches to forming a silicon oxide thin film are... 

Etch thin-film electrode and sacrificial metal layer... 

PCSL microfabrication is an attractive alternative for making robustly enclosed microchannels by solvent bonding, while protecting microchannel integrity using a sacrificial material. This technique does not require sophisticated thin-film deposition instrumentation and should be easy to implement by microfluidics researchers. In the next section, we provide guidelines for the fabrication of polymer microfiuidic systems using PCSLs. 

Chan, K., and Gleason, K. K., Air-gap fabrication using a sacrificial polymeric thin film synthesized via initiated chemical vapor deposition, J. Electrochem. Soc., 153, C223, 2006. 

Given the birth of MEMS from the IC industry, the dominant material used in the early devices was silicon. The use of silicon as a substrate and structural material, and the use of polysilicon as a thin film structural material, has continued to the present day for several reasons. The microfabrication techniques for silicon are highly developed and flexible, the microfabrication equipment has been designed for silicon, the properties of silicon are very well known and can be tightly controlled, silicon has excellent mechanical properties, and silicon has an insulating native oxide that can be used as a sacrificial layer. Other thin film materials that are commonly used in MEMS include silicon nitride, metals, and conventional polymers, such as polyimide. 

---