Please answer the following questions on lithography In a cl

Please answer the following questions on lithography: In a clean room facility used for semiconductor processing, name two important contaminants and what type of problem do they cause. Name the two types of flats on a silicon wafer. What is the purpose of each flat type, and what aspect of the flat position is used to indicate the information about the wafer. GaAs and Silicon are both used in semiconductor devices, but seldom is both used m the same cleanroom Name at least two reasons why that is so. Extreme ultra violate (EUV) source with a wavelength of lambda = 13nm) is expected to be used for CMOS fabrication in the next decade What is the smallest feature size (F) and dept of Focus for this tool. Give one examples for its benefits and challenges.

Solution

(a). The main two contaminant materials include: poisonous elemental dopants such as sodium, arsenic, phosphorus and chemicals.

Presence of electrically active impurities or contaminants like dopants can alter device performance. These impurities are called mobile ionic contaminants (MICs). These are ions that have high mobility in the semiconductor. They can cause failure even after packaging.

The other contaminant, unwanted chemicals contaminate process chemicals and deionized water that are used in various steps in the fabrication process.

Problems:

(b). Flats are cut in the single crystal rods and helps wafers to get orientated and identified.

The two types of flats are:

(c). GaAs and Si are not used in the same clean room because of cross contamination problem.

This affect can mainly be observed in two areas: processed tools used and environmental waste handling.