The extension of Moore’s Law has become of the utmost importance as technology continuously shifts to that of advanced healthcare, artificial intelligence (AI), and internet of things (IoT). To meet consumer demands in sub-7 nm technologies, chemical mechanical planarization (CMP) has become a critical step in advanced integrated circuit manufacturing. Furthermore, the complexity of slurry formulations has increased exponentially to become stimuli responsive to modulate rate (i.e., enhance or suppress) in-situ. Commonly, this modulation is achieved through mechanical polishing parameters, such as downforce, flow rate, and platen speed. These parameters effectively increase the chemical activity of a slurry via kinetic/thermodynamic processes; however, they can also manifest in increased defectivity (i.e., scratches and dishing/erosion) due to higher shear force/friction. Therefore, the development of a “smart” responsive slurry using a non-mechanical stimulus, such as light, is crucial. This work focuses on the development of a photo-switching slurry in which upon irradiation the CeO2 nanoparticle surface activity changes to ultimately tune oxide removal rate. It is widely reported that the oxide removal mechanism is a chemical tooth reaction in which TEOS directly attacks the oxygen vacancies on the CeO2 surface; therefore, increasing the oxygen vacancy concentration (i.e., Ce3+ state) enhances oxide removal rate. This presentation will discuss a photo-induced adsorption/desorption mechanism in which a functional additive blocks the active surface sites (i.e., oxygen vacancies) and upon irradiation is released. More specifically, a photosensitizer is excited which results in the oxidization, and subsequent desorption, of the functional additive which alters the oxygen vacancy availability at the CeO2 surface. Results have shown that this photoactive slurry has a removal rate 2800 Å/min in no light conditions and upon irradiation increases to 3450 Å/min.

Developing photoactive slurry formulations for the modulation of oxide removal rate in shallow trench isolation (STI) chemical mechanical planarization (CMP)

ACS Spring Meeting 2021

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