Characterization of Cu surface cleaning by hydrogen plasma

Abstract

When a Cu surface is exposed to a clean room ambient, a surface layer containing Cu 2 O, CuO, Cu͑OH͒ 2 , and CuCO 3 is formed. Thermal treatment in a vacuum combined with hydrogen plasma can remove this layer. Water and carbon dioxide desorb during the thermal treatment and the hydrogen plasma reduces the remaining Cu oxide. Ellipsometric, x-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectroscopy analyses indicate that the mechanism of interaction of the H 2 plasma with this layer depends on temperature. When the temperature is below 150°C, H 2 plasma cannot completely reduce Cu oxide. Hydrogen diffuses through the oxide and hydrogenation of the Cu layer is observed. The hydrogenated Cu surface has a higher resistance than a nontreated Cu layer. The hydrogen plasma efficiently cleans the Cu surface when the substrate temperature is higher than 150°C. In this case, hydrogen atoms have enough activation energy to reduce Cu oxide and adsorbed water forms as a byproduct of Cu oxide reduction. When the wafer temperature is higher than 350°C, the interaction of the Cu film with hydrogen and residual oxygen is observed.

Unraveling the oxidation of Ru using XPS

“…The single crystal sample was placed inside a UHV chamber (base pressure less than 5×10 −8 Pa), coupled to an instrument for XPS analysis (PHI 5400 ESCA with base pressure less than 1 × 10 −8 Pa). The sample surface was cleaned by subjecting it to atomic hydrogen [9] for 1 h, followed by ion sputtering with 2 keV Ar + for 30 min. The sample was subsequently annealed at 873 K to allow for full recovery of any damage induced by the ion sputtering process.…”

A Global Enhanced Vibrational Kinetic Model for High-Pressure Hydrogen RF Discharges

“…H YDROGEN plasmas are found in positive and negative ion sources, radio-frequency (RF) capacitative and microwave reactors, and propulsion devices and have diverse applications in microelectronics [1], [2], aerospace, fusion [3], material processing [4], plasma-enhanced chemical vapor deposition [5], and particle accelerators [6]- [8]. Negative hydrogen ion sources (NHIS), which are the primary interest of this paper, have been used extensively over the last three decades [9], [10].…”

Effects of Surface Cleaning on Stressvoiding and Electromigration of Cu-Damascene Interconnection

“…Ta (TaN) is selected as the Cu diffusion-barrier metal in this paper. When Cu surface is exposed at a clean-room ambient, a surface layer containing Cu 2 O, CuO, Cu(OH) 2 , and CuCO 3 are formed [10]. Prior to Cu diffusion-barrier layer deposition into the metal trench, a precleaning process is necessary to clean via bottoms, which will reduce the via resistance and improve yield.…”