Chemical mechanical planarization of patterned InP in shallow trench isolation (STI) template structures using hydrogen peroxide–based silica slurries containing oxalic acid or citric acid

• Published in: Microelectronic engineering Vol. 116; pp. 17 - 21
• Main Authors: Matovu, John B., Ong, Patrick, Teugels, Lieve G., Leunissen, Leonardus H.A., Babu, S.V.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.03.2014; Elsevier
• Subjects: Applied sciences; Chemical mechanical polishing; Citric acid; Condensed matter: structure, mechanical and thermal properties; Design. Technologies. Operation analysis. Testing; Dishing; Electronics; Exact sciences and technology; Indium gallium arsenides; Indium phosphides; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Integrated circuits; Mechanical and acoustical properties; Microelectronic fabrication (materials and surfaces technology); Oxalic acid; Oxide loss; Physical properties of thin films, nonelectronic; Physics; Planarization; Scanning electron microscope; Scanning electron microscopy; Scanning probe microscopes, components and techniques; Selectivity; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Shallow trench isolation; Silicon dioxide; Slurries; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Trenches; Wafers; Shallow trench isolation; Planarization; Dishing; Oxalic acid; Oxide loss; Selectivity; Chemical mechanical polishing; Scanning electron microscope; Citric acid; Scratching test; Binary compound; Hydrogen peroxide; n channel; IV-VI compound; Indium phosphide; Template method; Microelectronic fabrication; Wear rate; Complementary MOS technology; Wafer; Scanning electron microscopy; Trench technology; Phosphine; Particle suspension; III-V compound; Insulation technology; Silicon oxides; Slurries
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2013.11.009

•Aq. silica containing H2O2 and oxalic or citric acid was used in CMP of InP–STI.•The slurries planarized the InP in the STI trenches.•Scratches, slurry particles and smearing of InP were absent on planarized surface.•Between 12 and 15nm of InP dishing were observed at pH 6.•The oxide loss was <20nm at pH 6 and 8 and <30nm at pH 10. The fabrication of an InGaAs n-channel in complementary metal oxide semiconductors (CMOS) requires an intervening layer of Indium Phosphide (InP) that should be planarized using chemical mechanical planarization (CMP) before deposition of the InGaAs layer. The InP CMP process has to provide good InP removal rates (RRs) (100–200nmmin–1), very low oxide loss, low dishing and minimal or no phosphine evolution. In this work, it is shown that aqueous slurries containing 3wt% silica, 1wt% hydrogen peroxide and 0.08M oxalic acid or citric acid satisfy these requirements. Cross–sectional scanning electron microscope (SEM) images showed that InP in the shallow trench isolation structures was planarized and scratches, slurry particles and smearing of InP on the wafers were absent. Additionally, wafers polished at pH 6 showed very low dishing values of about 12–15nm, determined by cross–sectional SEM.