Question

Describe the basic mechanism by which positive photolithography transfers a pattern, and comment on the chemical interactions of the resist throughout the entire process.

Answer 1

Photo-lithography is the method of giving geometric shapes on a mask to the surface of a silicon wafer.

Explanation:

The fabrication of an integrated circuit (IC) requires a variety of physical and chemical processes conducted on a semiconductor (e.g., silicon) substrate. In common, the numerous methods used to create an IC fall into three divisions: film deposition, patterning, and semiconductor doping.

Films from both conductors (such as polysilicon, aluminum, and extended recently copper) and nonconductors (various forms of silicon dioxide, silicon nitride, and others) are utilized to combine and separate transistors and their parts.

Selective doping of different regions of silicon permits the conductivity of the silicon to be altered with the application of voltage. By building structures of these various parts millions of transistors can be assembled and wired together to form the complex circuitry of a modern microelectronic device.  

Fundamental to all of these methods is lithography, i.e., the development of three-dimensional relief images on the substrate for subsequent transfer of the model to the substrate.