Effects of H₂O₂ and pH on the Chemical Mechanical Planarization of Molybdenum

Abstract

The effects of H 2 O 2 on the chemical etching and removal rate (RR) of molybdenum (Mo) were investigated. Static etch rate (SER) and chemical mechanical planarization (CMP) experiments were performed using H 2 O 2 -based slurries at different pH levels. X-ray photoelectron spectroscopy (XPS) and potentiodynamic polarization analysis showed the formation of Mo oxides by the reaction between Mo and H 2 O 2 . The Mo SER, which increased with H 2 O 2 concentration, supported the dissolution of Mo oxides through the formation of peroxo Mo complexes with H 2 O 2 . The CMP removal mechanism was demonstrated by comparing the CMP RR with and without silica abrasives. In addition, the Mo oxidation rate by H 2 O 2 on a millisecond time scale was characterized with chronoamperometry to explain different RRs at pH values ranging from 2 to 8. The CMP RR of Mo was high at pH 2 and pH 10; however, pH 2 showed a lower SER than pH 10, leading to lower surface roughness.

Controlled Stepwise Wet Etching of Polycrystalline Mo Nanowires

“…We chose an aqueous hydrogen peroxide (H 2 O 2 ) solution as a chemical etchant, which is the most commonly used etchant for Mo. [26,27] Before the etching, Mo NWs were smooth and straight, featuring only a minor waviness (Figure 2A). The selected area electron diffraction (SAED) pattern of the NWs corresponds to pure Mo metal with 〈110〉 texture, and we estimated the average grain size of ≈22 nm from TEM images.…”

“…The etching with H 2 O 2 aqueous solution proceeds via sequential Mo oxidation to MoO 2 (Mo 4+ oxidation state) and MoO 3 (Mo 6+ oxidation state). [26,27] The latter is soluble in water and, therefore, leaves the NW surface, while MoO 2 with Mo 4+ stays on the metal surface, waiting to be oxidized further. The dynamics of this process depend on the relative rates of Mo 0 /Mo 4+ oxidation and Mo 6+ dissolution.…”

Simulation and Experimental Investigation of the Radial Groove Effect on Slurry Flow in Oxide Chemical Mechanical Polishing

“…As nodes are shrinking in semiconductor fabrication, chemical mechanical polishing (CMP), the process to achieve global and local planarization of the wafer surface, is also facing some emerging problems, such as defect control, novel material CMP, and green CMP [1][2][3][4]. Continuous optimization of the consumables, polishing recipe, and postprocessing is needed to solve contemporary challenges.…”

A novel high-quality and high-efficiency immersion fluid chemical mechanical polishing process for integral impellers

“…Chemical mechanical polishing (CMP) is a precision machining technology that uses a coupling mechanism of chemical etching and mechanical micro-cutting remove to achieve ultra-smooth surfaces of workpieces [17]. Science CMP can achieve sub-nanometer and ultra-low damage polishing of parts, it is widely used in aviation, aerospace, microelectronics and other fields, such as sapphire [18,19], quartz [20], silicon [21], silicon carbide [22,23], diamond wafers [24] and pure copper [25,26], nickel-based alloys [27], titanium alloys [28,29] and other difficult-to-machine materials for ultra-precision machining.…”