Achieving smooth PZT surface via chemical mechanical polishing with ethylenediamine dihydrochloride. Issue 13 (1st July 2022)

• Record Type: Journal Article
• Authors: Wu, Yuan; Jiang, Liang; Qian, Linmao
• Is Part Of: Ceramics international. Volume 48:Issue 13(2022)
• Page Start: 18891
• Page End: 18898
• Publication Date: 2022-07-01
• Subjects: Chemical mechanical polishing -- Lead zirconate titanate -- Surface roughness -- Complexing agent -- Ethylenediamine; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.03.168
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Lead zirconate titanate (PZT) has been widely used in microelectromechanical systems and ferroelectric memory, and a high-quality PZT surface is important to the device performance. In this study, chemical mechanical polishing (CMP) was introduced to process PZT-4 (Pb(Zr0.44 Ti0.56 )O3 ). A complexing agent ethylenediamine dihydrochloride (EDA·2HCl) was used as a crucial chemical additive in slurries to improve the CMP performance of PZT-4 because it may chelate metal ions of PZT-4, such as Ti 4+ . The results show that the material removal rate (MRR) of PZT-4 decreases and the surface roughness S a increases as pH increases. At pH 4.0, with the EDA·2HCl concentration increasing, the MRR first increases, reaches the summit of 498 nm/min at 0.75 mM, and then decreases and levels off. The S a has a similar trend. With 50 mM EDA·2HCl, the S a reaches the minimum value of 3.5 nm, and no processing damage occurs in the substrate. For the removal mechanism, EDA can be adsorbed on PZT-4 probably via forming complex with Ti 4+ . With a low content of EDA·2HCl, the adsorbates of EDA distribute discretely and can be removed easily, and thus the MRR is high. As the content of EDA·2HCl increases, a relatively continuous and uniform film is formed to suppress dissolution and abrasion, and thus the MRR decreases. A two-step CMP process was developed, and a smooth PZT surface can be rapidly achieved. This study provides mechanistic insight of the role of EDA in the CMP of PZT-4, and may open new avenues of developing CMP slurries for achieving smooth surfaces of PZT materials via screening prospective complexing agents.