(Invited) Controlling Nano-Scale Chemically Modified Thin Films for Chemical Mechanical Planarization
Authors: Basim Gul Bahar 
Published: July 2021

This is a review paper on the effect of chemicals modified thin films on CMP process development. As the microelectronics manufacturing faces the challenges related to the Beyond Moore’s Scale adaptation, Chemical Mechanical Planarization (CMP) process control becomes much more critical yet difficult simultaneously. The need for planarizing larger scale wafers at an atomic scale precision with superior removal rate selectivity and zero defect focus demands a nano-scale control on the process performance. This study reviews the atomic scale chemical and mechanical interactions on CMP as it applies to traditional as well as the next generation materials in microelectronics manufacturing. Once the behavior of the wafer surface is understood at an atomic level, the process control metrics can be tuned accordingly.

In an attempt to come up with the design criteria for the slurry chemistry, chemically modified layer formation is evaluated on conducting, semiconducting and insulating materials as a function of evaluating the nano-scale surface topography and change in surface energy. Metallic films are studied in terms of their corrosion and passivation behavior through macro-scale electrochemical evaluations as well as the surface sensitive characterization techniques such as XRR, XRD and FTIR [1, 2]. In addition, a modeling approach is introduced through Cahn Hilliard Equation (CHE) approximation to the surface energy minimization on the metal-oxide formation by nucleation [3]. Furthermore, removal rate selectivity properties of the semiconductor materials are discussed on conventional and III-V semiconductors and insulators as a function of chemically modified film alteration [4-5]. Some high-end applications such as (i) tungsten T-gate transistors, (ii) new liner/barrier materials [6], (iii) germanium based high-speed, shallow trench isolation transistors and (iv) high-power transistors and LED applications where III/V semiconductors are deliberated. As a new challenge, 3-D implementations of the CMP process, where the chemically modified nano-films impact the materials performance are also introduced.

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