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In semiconductor fabrication, etching is one of the major steps, along with photolithography and thin-film deposition. It involves removing unwanted materials from the surface of a wafer using chemical or physical methods. This step is carried out after coating, photolithography, and developing. It is used to remove the exposed thin film material, leaving only the desired portion of the wafer, and then removing the excess photoresist. These steps are repeated numerous times to create complex integrated circuits.

As the world looks for new opportunities in semiconductors, gallium nitride continues to stand out as a potential candidate for future power and RF applications. However, for all the benefits it offers, it still faces a major challenge; there are no P-type (P-type) products. Why is GaN touted as the next major semiconductor material, why is the lack of P-type GaN devices a major drawback, and what does this mean for future designs?

Currently, many semiconductor devices employ mesa device structures, which are predominantly created through two types of etching: wet etching and dry etching. While the simple and rapid wet etching plays a significant role in semiconductor device fabrication, it has inherent drawbacks such as isotropic etching and poor uniformity, which result in limited control when transferring small-sized patterns. Dry etching, however, with its high anisotropy, good uniformity, and repeatability, has become prominent in semiconductor device fabrication processes. The term “dry etching” broadly refers to any non-wet etching technology used for removing surface materials and transferring micro and nano patterns, including laser etching, plasma etching, and chemical vapor etching. The dry etching discussed in this text specifically pertains to the narrow application of processes using plasma discharge—either physical or chemical—to modify material surfaces.

In semiconductor manufacturing, the precision and stability of the etching process are paramount. One critical factor in achieving high-quality etching is ensuring that wafers are perfectly flat on the tray during the process. Any deviation can lead to uneven ion bombardment, causing undesirable angles and variations in etching rates. To address these challenges, engineers have developed Electrostatic Chucks (ESCs), which have significantly improved etching quality and stability. This article delves into the design and functionality of ESCs, focusing on one key aspect: the electrostatic principles behind wafer adhesion.

The basic crystal unit cell of monocrystalline silicon is the zinc blende structure, in which each silicon atom bonds chemically with four neighboring silicon atoms. This structure is also found in monocrystalline carbon diamonds.

The wafer notch is a V-shaped or U-shaped groove on the edge of a semiconductor wafer. Far from being a defect incurred during the manufacturing process, it is the critical structural marker that was intentionally designed, whose core function lies in enabling precise positioning and orientation identification of the wafer. Wafer flat was used as the orientation marking in the early stages of wafer technology development. However, as wafer sizes gradually increased, the flat-edge design occupied more effective area, thus being gradually replaced by the more compact notch.