Kuivsöövitus

Kuivsöövitus, also known as dry etching, is a process used in microfabrication to remove material from a substrate in a controlled manner. It is a key step in the production of integrated circuits and other microelectronic devices. Unlike wet etching, which uses liquid chemicals, dry etching employs a plasma to etch the material. This plasma is typically generated by applying radio frequency (RF) power to a gas within a vacuum chamber.

The etching process in dry etching can be primarily physical, chemical, or a combination of both. Physical etching, often referred to as ion bombardment, involves energetic ions from the plasma striking the substrate and physically dislodging material. This can lead to anisotropic etching, where the etching rate is significantly higher in one direction than others, which is crucial for creating vertical sidewalls. Chemical etching, on the other hand, relies on reactive species within the plasma that chemically react with the substrate material, forming volatile byproducts that are then pumped away.

Common dry etching techniques include reactive ion etching (RIE) and deep reactive ion etching (DRIE). RIE is a versatile process used for a wide range of materials. DRIE is specifically designed for etching very deep and high-aspect-ratio structures, often used in MEMS (Micro-Electro-Mechanical Systems) fabrication. The choice of gas chemistry, pressure, RF power, and substrate temperature are critical parameters that determine the etching rate, selectivity (the ratio of etching rates between the material to be etched and a mask material), and anisotropy. Dry etching offers advantages such as excellent control over etch profiles and the ability to etch a wide variety of materials, including semiconductors, metals, and dielectrics.