Redox Activation of Diamond Substrates for Advanced Chemical Mechanical Planarization (CMP)
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2025-07-11 |
| Journal | ECS Meeting Abstracts |
| Authors | K. M. Smith, Andrew C. Murphy, Connor J Keating, Jason J. Keleher |
Abstract
Section titled āAbstractāDiamond is gaining traction as a wide band gap substrate (WBG) for high-powered devices due to its intrinsic properties (i.e., high hardness/bulk modulus, thermal conductivity, light transmittance, band gap, chemical stability, and nitrogen-vacant center). Chemical Vapor Deposition (CVD) is regularly used to achieve diamond substrate growth, but the high temperatures involved in this process to promote nucleation and growth often lead to surface and subsurface-level defects. Reported defects include poor adhesion, stress from lattice mismatch, and potential contamination from the substrate material itself, particularly when trying to grow large, high-quality diamond crystals, and significant post-processing roughness due to laser cutting. To remedy this, chemical mechanical planarization (CMP) is often employed, which relies heavily on mechanical mechanisms such as increases in temperature and pressure, while the chemical component is often neglected. Due to the presence of exposed surface bonds on the diamond, it is possible to enhance the chemical activity of the CMP process via surface redox activation. Previous work has shown that using an oxidizing agent such as potassium permanganate (KMnO 4 ) in the presence of hard nanoparticle abrasives creates a suitable triboelectrochemical environment for removal, albeit still under high shear stress conditions. This work will explore modulating the oxidative and reductive environment using greener redox chemistries and functionalized nanoparticles to enhance the diamond removal rate and improve surface defectivity. Initial work utilizes biomimetic redox-active complexes, such as organometallic complexes (OMCs) and boron-based compounds, to simulate KMnO 4 -like surface activity during the CMP process. OMCs allow for enhanced surface-slurry interactions and undergo Fenton-like oxidation in the presence of H 2 O 2 to produce reactive oxygen species (ROS). These slurries show enhanced removal rate associated with the type of OMC used, which correlates to both the size of the electrophilic area and the amount of ROS generated. Electrochemical analyses, such as cyclic voltammetry and linear sweep voltammetry, have been shown to correlate to ROS production, which is believed to be the key component for enhanced surface modification and lower-stress removal.