Effect of ammonium halide salts on wet chemical nanoscale etching and polishing of InGaAs surfaces for advanced CMOS devices. (July 2023)

• Record Type: Journal Article
• Authors: Samanta, Suprakash; Jin, Seungwan; Lee, Chan-Hee; Lee, Seong-Soo; Struyf, Herbert; Kim, Tae-Gon; Park, Jin-Goo
• Is Part Of: Applied geography. Volume 161(2023)
• Publication Date: 2023-07
• Subjects: InGaAs -- Nanoscale etching -- CMP -- Slurry formulation -- Ammonium halide salts -- Alkaline slurry; Geography -- Periodicals; Human geography -- Periodicals; Human ecology -- Periodicals; 910
• DOI: 10.1016/j.mssp.2023.107469
• Languages: English
• ISSNs: 0143-6228

Abstract

Abstract: Wet surface treatment of InGaAs is crucial for high-performance complementary metal-oxide semiconductor (CMOS) devices as it reduces material loss and oxide formation in the InGaAs layer. In this present study, the surface chemistries of In0.53 Ga0.47 As during wet chemical etching and the chemical-mechanical planarization (CMP) process in acidic (HCl/H2 O2 /H2 O mixture) and alkaline (NH4 OH/H2 O2 /H2 O mixture) solutions were investigated. Elemental oxide formation, surface termination, and stoichiometry after the chemical etching/CMP process were investigated through X-ray photoelectron spectroscopy and atomic force microscopy. In wet chemical etching, the dissolution of the InGaAs elemental oxide was more prominent in acidic HCl mixture solutions compared to alkaline NH4 OH mixture solutions. It was observed that the overall surface etching was more aggressive in acidic solution, whereas the alkaline solution provided higher surface roughness (Ra, ∼7.19 nm, scanning area of 5 μm × 5 μm) due to the lower dissolution capacity of indium oxide. The effects of the oxidizer and the slurry pH on the removal rate, Ra, and surface contamination were evaluated after the InGaAs CMP process. A high removal rate (∼110 nm/min) and considerably lower surface contamination were obtained using an alkaline slurry (pH 10). A novel InGaAs CMP slurry is developed by adding different ammonium halide salts to the alkaline slurry for improving surface roughness and removal rate. The addition of ammonium halide salts to an alkaline slurry was very effective in achieving a higher removal rate (∼175 nm/min) and smoother surface (Ra < 0.6 nm) with lower contamination during the InGaAs CMP process. Graphical abstract: Image 1 Highlights: H2 O2 concentration in acidic/alkaline solution is a key factor for nanoscale etching of InGaAs. Chemical etching depends on oxidation followed by the dissolution of III-V elemental oxides. InGaAs CMP using silica slurry at pH 10 resulted in a higher removal rate and low particle contamination. The removal rate is increased by 60% after adding ammonium halide salts to alkaline slurry with reduced surface roughness. Ammonium halide salts added alkaline slurries exhibited negligible particle contamination during InGaAs CMP process.