Microstructural Analysis of Copper Foil Etched and Annealed in ECR Plasma Reactor

Abstract

Microstructural analysis of commercially available cold-rolled polycrystalline copper foil, etched and annealed in an in-house developed Electron Cyclotron Resonance (ECR) Plasma Enhanced Chemical Vapour Deposition (PE-CVD) reactor, have been carried out using x-ray diffraction (XRD) studies. The annealing experiments were carried out under a vacuum environment, keeping the working pressure of the reactor at 50×10-3 mbar, for three different time spans of 30 mins, 45 mins and 1 hour at 823 K (550 °C) and 923 K (650 °C) respectively in presence of hydrogen plasma. The XRD studies reveal the significance of annealing time at two different temperatures for the determination of physical and microstructural parameters such as the average grain size and micro-strain in copper lattice by Williamson-Hall (W-H) method.

Microstructural Characteristics of ECR Plasma Etched and Heat Treated Commercial Copper Foil

“…Hydrogen plasma was created in the system by injecting H 2 gas (purity: 99.999%) to carry out plasma etching and heat treatment of the substrate simultaneously. Plot of average grain size as estimated from various models (UDM, [16,17] USDM, and UDEDM) of W-H analysis for different experimental conditions.…”

“…The authors have estimated the average domain size and micro-strain from uniform deformation model (UDM) of W-H analysis for the present experiments in their previous work. [16,17] UDM assumes that copper foil is isotropic in nature considering strain is uniform throughout the crystallographic direction. Hence, an anisotropic consideration is essential to calculate the microstructural parameters precisely.…”

“…Copper foils were pre-cleaned in acetone and placed on top of a Heater Assembly as shown in Figure 5 inside the Electron Cyclotron Resonance (ECR) Plasma Enhanced Chemical Vapor Deposition (PE-CVD) reactor. [16,17] The Heater Assembly was made of a 60 Ω nichrome wire and driven by an external variable DC power supply to generate heat. The nichrome wire was placed around a specially designed insulating ceramic block which was further encapsulated by a stainless-steel inverted cylindrical pot in order to confine the heat flux.…”

“…The average crystallographic grain size (D) as estimated from W-H method assuming UDM, [16,17] USDM, and UDEDM for all copper samples are presented in Figure 4. A variation in D value for unprocessed copper foil is observed and is believed to be due to the inherent strain and crystal dislocations obtained by cold-rolling process.…”

“…Figure 4.Plot of average grain size as estimated from various models (UDM,[16,17] USDM, and UDEDM) of W-H analysis for different experimental conditions.…”