Stripping of Cr and CrN thin films by electrochemical methods

• Main Authors: Zheng-zhi Zhang, 張政誌
• Other Authors: Fu-Hsing Lu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/03215788121756015194

碩士 === 國立中興大學 === 材料工程學研究所 === 93 === Abstract This research mainly employs electrochemical methods under alkaline condition to strip the chromium nitride (CrN) and chromium (Cr) thin films that were deposited by cathodic arc plasma technique on Si wafer. Different current density, concentration of KOH solution, and stripping time were used to investigate their influences on shortest completely stripping time, required electric charge, stripping rate, and weight loss. A mathematical expression is also utilized to analyze the relationship between film thickness, current density, and stripping time. During CrN and Cr thin films stripping, the KOH solution turned from colorless into faint yellow, which is due to that such film dissolved in alkaline solution becoming CrO42- ion. The shortest completely stripping time could be obtained from the relation of responded potential and stripping time tc and such time is shown inverse proportion to the current density. However, the tc shows independent of the concentration of KOH solution. Films thickness decreases with stripping time in all stripping process and the relation between these two factors could be described as L/L0 = 1-(t/tc)n. The obtained n value approximate 0.5~1. This indicates that both CrN and Cr film might have a similar stripping mechanism. The stripping rate of CrN film shows more rapid than the Cr film. The required charge of stripping for CrN film is about 1.5 times larger than that for Cr film. This could be due to the difference of chemical reaction intermediate, dissimilarity of microstructure, the micro-particles generated on the CrN surface. The weight loss of stripped film could be calculated by the stripping the volume as well as the Faraday's law and the value obtained from later is smaller. In addition, acid electrolyte and the scanning voltage mode can be used to also successfully stripping the films.