Abstract
Coating the inner surfaces of high-powered plasma processing equipment has become crucial for reducing maintenance costs, process drift, and contaminants. The conventionally preferred alumina (Al2O3) coating has been replaced with yttria (Y2O3) due to the long-standing endurance achieved by fluorine-based etching; however, the continuous increase in radio frequency (RF) power necessitates the use of alternative coating materials to reduce process shift in a series of high-powered semiconductor manufacturing environments. In this study, we investigated the fluorine-based etching resistance of atmospheric pressure-sprayed alumina, yttria, yttrium aluminum garnet (YAG), and yttrium oxyfluoride (YOF). The prepared ceramic-coated samples were directly exposed to silicon oxide etching, and the surfaces of the plasma-exposed samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. We found that an ideal coating material must demonstrate high plasma-induced structure distortion by the fluorine atom from the radical. For endurance to fluorine-based plasma exposure, the bonding structure with fluoride was shown to be more effective than oxide-based ceramics. Thus, fluoride-based ceramic materials can be promising candidates for chamber coating materials.
Highlights
Three-dimensional semiconductors with high aspect ratios have been extensively investigated to achieve high-performance, multifunctional, and miniaturized semiconductor devices, and high-density plasma processes comprising high-powered etching have become essential for the fabrication of dynamic random-access memory capacitors
Ceramic coating materials investigated in this research include aluminum oxide, yttrium oxide, yttrium aluminum garnet (YAG), and yttrium oxyfluoride (YOF)
Al2O3 has been widely adopted in various fields due to its low cost and high mechanical strength, and many ceramic components of plasma equipment are still made from alumina
Summary
Three-dimensional semiconductors with high aspect ratios have been extensively investigated to achieve high-performance, multifunctional, and miniaturized semiconductor devices, and high-density plasma processes comprising high-powered etching have become essential for the fabrication of dynamic random-access memory capacitors. The etching is conducted by both physical ion bombardment and chemical reaction on a wafer surface; on the other hand, etching in fluorine-based plasma may cause a chemical reaction between the fluorine plasma and interior coating material of the process chamber, forming fluoride layers and desorption of fluoride particles by physical bombardment [1]. When the chamber wall and components are exposed to a high-density plasma environment over a given time, surface erosion occurs due to the chemisorption and physisorption of fluorinated compounds contaminating the chamber [3].
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