2.3. Emergence of Micromachining

In the 1970s and 1980s, researchers began exploring micromachining techniques adapted from IC fabrication to produce mechanical elements.

During the decades of the 1970s and 1980s, new techniques in micromachining were developed. Micromachining refers to the process of fabricating small mechanical elements that can work alongside electronic components, particularly those from integrated circuits (ICs). This time marked a pivotal shift where mechanical elements were not just standalone but were integrated into the increasingly smaller and efficient devices powered by IC technology.

Think of micromachining like assembling a tiny mechanical watch. Just as a watchmaker carefully plans to incorporate gears and springs within a small case, researchers were learning to fit tiny mechanical components inside electronic circuits.

Bulk Micromachining: Etching cavities into silicon wafers became a standard technique.

Bulk micromachining is a process that involves removing material from bulk silicon wafers to create cavities or structures. This technique allows for the fabrication of various mechanical components by etching away parts of the silicon. The idea is to create mechanical structures that are fully integrated within the material. This method became a staple in MEMS fabrication since it provided the necessary precision and control to create small scale mechanical systems.

Imagine sculpting a marble statue. The sculptor chips away at the stone to reveal the figure within, just as researchers chip away at silicon wafers to reveal intricate mechanical structures that will function in micro devices.

Surface Micromachining: Thin-film deposition and patterning enabled more complex and integrated microstructures.

Surface micromachining is another technique that builds on top of the silicon substrate by adding layers of materials in thin films. This process allows for the creation of more complex geometries and microstructures. Techniques such as deposition, where layers of material are added, and patterning, where specific shapes are defined, are crucial in developing devices like sensors or actuators. It enabled researchers to create intricate devices that could perform multiple functions in a limited space.

Think about building a multi-layer cake, where each layer can represent a different function or part of a device. By stacking layers of cake carefully and decorating them, you create something intricate and well-functioning, just like surface micromachining builds complex devices layer by layer.

Capacitive sensors: The development of micromachined capacitive accelerometers gained momentum in this period.

Capacitive sensors, particularly capacitive accelerometers, emerged as significant advancements during the 1970s and 1980s. These devices measure acceleration based on changes in capacitance caused by the movement of masses. The development during this time allowed companies to produce highly sensitive sensors that could be miniaturized and integrated into various applications, including automotive and consumer electronics. This marked the beginning of widespread adoption of MEMS technology in various industries.

Consider a person riding a roller coaster. As they go up and down, their body experiences changes in force and motion, which could be tracked with a sensitive accelerometer. Just like a ride would measure the thrill of movement, capacitive accelerometers measure acceleration and movement in various devices, making them crucial for modern technology.

--