Role of the dense amorphous carbon layer in photoresist etching

Journal Article · Tue Dec 19 00:00:00 EST 2017 · Journal of Vacuum Science and Technology A

DOI:https://doi.org/10.1116/1.5009640· OSTI ID:1660332

Pranda, Adam ^[1]; Gutierrez Razo, Sandra A. ^[2]; Tomova, Zuleykhan ^[2]; Fourkas, John T. ^[2]; Oehrlein, Gottlieb S. ^[2]

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1. University of Maryland, College Park, MD (United States); University of Maryland
2. University of Maryland, College Park, MD (United States)

The development of new photoresists for semiconductor manufacturing applications requires an understanding of the material properties that control the material’s plasma etching behavior. Ion bombardment at ion energies of the order 100 s of eV is typical of plasma-based pattern-transfer processes and results in the formation of a dense amorphous carbon (DAC) layer on the surface of a photoresist, such as the PR193-type of photoresist that currently dominates the semiconductor industry. Prior studies have examined the physical properties of the DAC layer, but the correlation between these properties and the photoresist etching behavior had not been established. In this work, the authors studied the real-time evolution of a steady-state DAC layer as it is selectively depleted using an admixture of oxygen into an argon plasma. Observations of the depletion behavior for various DAC layer thicknesses motivate a new model of DAC layer depletion. This model also correlates the impact of the DAC layer thickness with the etch rate of the bulk photoresist. The authors find that up to a 40% depletion of the DAC layer thickness does not have a significant impact on the bulk photoresist etch rate. However, further depletion results in an exponential increase in the etch rate, which can be up to ten times greater at full depletion than for the fully formed DAC layer. Thus, with these trends the authors show that the photoresist etch rate is controlled by the thickness of the DAC layer. Furthermore, thickness loss of the DAC layer in an O2-containing plasma coincides with a chemical modification of the layer into an oxygen-rich surface overlayer with properties that are intermediate between those of the DAC layer and the bulk photoresist. Support for this interpretation was provided via x-ray photoelectron spectroscopy characterization. Atomic force microscopy was used to gauge the impact on surface roughness as the DAC layer is formed and depleted. Here, the trends established in this work will provide a benchmark in our development of new photoresists, which will be suitable for pattern transfer processes that will ultimately be a part of enabling smaller semiconductor device feature sizes and pitches.

• Research Organization: University of Maryland, College Park, MD (United States)
• Sponsoring Organization: National Science Foundation; USDOE; USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• Grant/Contract Number: SC0001939
• OSTI ID: 1660332
• Alternate ID(s): OSTI ID: 1541662; OSTI ID: 1414017
• Journal Information: Journal of Vacuum Science and Technology A, Journal Name: Journal of Vacuum Science and Technology A Journal Issue: 2 Vol. 36; ISSN 0734-2101
• Publisher: American Vacuum Society / AIP
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Photoresists
atomic force microscopy
carbon based materials
chemical elements
etching
light sensitive materials
materials treatment
plasma
plasma processing
semiconductor devices
semiconductor manufacturing
semiconductors
x-ray photoelectron spectroscopy