JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV MEMS DESIGN Previous Question Paper (July - 2023 - R16)

Nanotechnology finds widespread application across various sectors, primarily due to the unique physical and chemical properties of materials at the nanoscale. Key applications include:

• Electronics: Development of smaller, faster, and more energy-efficient transistors, high-density memory storage, and flexible displays.
• Medicine: Targeted drug delivery systems, advanced diagnostic imaging, and tissue engineering scaffolds.
• Materials Science: Creation of lightweight, high-strength composites, self-cleaning surfaces, and improved catalysts for chemical manufacturing.
• Energy: Enhanced efficiency in solar cells, high-capacity batteries, and improved fuel cell membranes.

Etching is a fundamental process in micromachining used to selectively remove material from a substrate, typically silicon, to create complex three-dimensional microstructures. Its primary role is to define the geometry of devices such as sensors, actuators, and fluidic channels by transferring a pattern from a mask into the underlying material.

The process is categorized into two main types:

1. Wet Etching: Uses liquid chemical etchants to remove material. It can be isotropic, where the etch rate is equal in all directions, or anisotropic, where the etch rate depends on the crystallographic orientation of the substrate, allowing for precise control over sidewall profiles.
2. Dry Etching: Uses reactive gases or plasma (e.g., Reactive Ion Etching) to remove material. This method offers superior control over anisotropy and allows for the creation of high-aspect-ratio features with vertical sidewalls, which is essential for advanced MEMS fabrication.

By controlling the etch rate, selectivity, and directionality, etching enables the realization of intricate mechanical components and cavities required for functional microsystems.