What is the Function of Focus Rings?

Focus rings are the essential components to ensure the uniformity and stability of the semiconductor etching processes. Through precise control of electric and thermal fields, focus rings can concentrate plasma on the wafer surface, ensuring consistent etching results across all locations on the wafer.

The functions of focus rings

1. Improve etching uniformity

In the etching process, focus rings can concentrate plasma on the wafer surface, which effectively guarantees uniform plasma density, ion bombardment angle, and energy levels across both the wafer edge and center regions. They correct the electric field distribution at the wafer edge, reducing etching rate, critical dimension, and morphology variations caused by edge effects, thus ensuring etching consistency across the entire wafer surface. If the focusing ring is excessively worn or there is no focal ring, plasma will diffuse from the wafer edge, ultimately causing non-conforming deviations in line width between the edge and center regions.

2. Protect electrostatic chuck

Focus rings are usually installed outside the wafer carrier surface of the electrostatic chucks, directly exposed to plasma bombardment and corrosion. This installment setup services as the physical barrier to prevent plasma from contacting the electrostatic chucks during the etching process, thereby significantly reducing the risk of plasma damage. Focus rings also can prevent byproducts generated during the etching process from adhering to the electrostatic chucks, thus avoiding performance degradation caused by chuck contamination and clogging. This greatly extends the electrostatic chucks’ maintenance cycle and lifespan, reducing equipment maintenance and replacement costs.

Focus rings are commonly made from high-purity quartz, silicon and silicon carbide materials. Thanks to their excellent comprehensive performance, silicon carbide materials gradually become the mainstream option for cutting-edge etching processes. As a trusted semiconductor focus ring supplier in China, Semicorex offers high-quality silicon carbide focus rings of various sizes to match the different requirements of etching equipment. Semicorex welcomes your inquiries and purchases at any time.