(Invited) A Review on the Role of Slurry Chemistry on Chemically Modified Thin Film Formation for CMP Applications

Abstract

Chemical Mechanical Planarization (CMP) process is currently facing the challenge of planarizing larger scale wafers at an atomic scale precision with superior removal rate selectivity and zero defect focus. While the horizontal dimensions of the processed wafers (x-axis and y-axis as the wafer diameter) extend up to 300 mm, the z-axis has to be planarized to a margin of a couple of hundred nanometers. This requirement highlights the need for fundamental understanding on the surface chemistry of the layers being exposed to the planarization process in terms of their interactions with the CMP slurry chemistry. Once the behavior of the wafer surface is understood at an atomic level, the process control metrics can be tuned accordingly. This paper reviews the role of slurry chemistry in effectively modifying the top surface films of the various materials including conductors, semiconductors and insulators exposed to CMP operations in semiconductor manufacturing. Metallic films are studied in terms of their corrosion and passivation behavior [1, 2] as well as through a modeling of the energy minimization through a Cahn Hilliard Equation (CHE) approach [3]. Furthermore, formation and selectivity properties of the semiconductor materials including conventional and III-V semiconductors and insulators were investigated [4-5]. Some high-end applications where the nano-scale chemically modified films critical are: Metal CMP applications of the tungsten T-gate transistors, new barrier materials, germanium based high-speed shallow trench isolation transistors and high-power transistors and LED applications where III/V semiconductors, such as GaN, are used. Ozdemir, Basim, G.B. “Effect of Chemical Mechanical Polishing on Surface Nature of Titanium Implants FT-IR and Wettability Data of Titanium Implants Surface After Chemical Mechanical Polishing Implementation”, Data in Brief, 10, P 20-25, 2017. Karagoz, A., and Basim, G.B. “Controlling Germanium CMP Selectivity through Slurry Mediation by Surface Active Agents”, ECS Journal of Solid State Science and Technology, CMP Special Issue, 4 (11) P5097-P5104, 2015. Karagoz, A., Sengul, , Basim, G.B., “A Cahn Hilliard Modeling of Metal Oxide Thin Films for Advanced CMP Applications”, 225th ECS Meeting – Orlando, Florida, USA, May 11-15, 2014, ECS Transactions, 61 (17) 15-20 (2014). Karagoz, A., Craciun, V., Basim, G.B., “Characterization of Nano-Scale Protective Oxide Films_ Application on Metal Chemical Mechanical Planarization”. ECS Journal of Solid State Science and Technology, 4 (2) P1-P8, 2015. Ozbek, S., Akbar, W., Basim, G.B. “ Optimized Process Design for GaN Chemical Mechanical Planarization” ECS Journal of Solid State Science and Technology, Special Issue on GaN-Based Electronics for Power, RF, and Rad-Hard Applications, 6-11, P S3084-S3092, 2017.