Microfabrication processes photolithography

Microfabrication uses photolithography and etching [277,278]. A time-multiplexed inductively coupled plasma etch process was used for making the microchannels. The microstructured plate is covered with a Pyrex wafer by anodic bonding. 

Typical microfabrication processes include the following steps wafer cleaning, photolithography, etching, thin film deposition, doping (by either thermal diffusion or ion implantation), bonding (wire and wafer bonding), and chemical-mechanical planarization (CMP).The complexity of microfabrication processes can be described by their mask count. This one represents the number of different pattern layers that will constitute the final device. Modem microprocessors are made with 30 masks while a few masks suffice for a microfluidic device or a laser diode. 

The emergence of several technologies in the last two decades has stimulated the development of a set of unconventional microfabrication processes that go beyond the limits imposed by standard photolithography. TPP is one of these tools. Its distinctive capabilities to create complex 3D architectures vith high resolution, positions TPP as a key enabling microfabrication method for future advancements. 

As with silicon, polyimide has also been used in IC fabrication processes. Polyimide is used as a dielectric and encapsulant because it provides good planarization, electrical insulation, and resistance to solvents. Polyimide thin films are patterned using standard microfabrication processes such as photolithography and reactive ion etching both photosensitive and nonphotosensitive formulations are available. 

---