Sputter damage by low energy charged particle irradiation

Sputter Yields with a QCM:

A 15cm 3 Molybdenum grid DC Kaufman ion source used equipped with a Faraday cup + Retarding Field Analyzer.

Results:

Conclusions:

Sputter yields for inert gases show threshold near expected value. Ruthenium allows high nitrogen implantation to occur and XPS peaks show possible nitridation.

Future work will involve exposure to thin ruthenium film samples which can be analysed by AR-XPS and X-Ray Reflectivity.

TRIDYN simulations to corroborate experimental data

Parikshit Phadke

, Marko Sturm

, Robbert van de Kruijs

and Fred Bijkerk

*e-mail: p.phadke@utwente.nl

1_{Industrial Focus Group XUV Optics, MESA}+ _{Institute for Nanotechnology, University of Twente, Enschede, The Netherlands}

Sputter Damage by Low Energy Charged

Particle Irradiation

Acknowledgements

Industrial Focus Group XUV Optics at the MESA+ Institute at the University of Twente, industrial partners: ASML, Carl Zeiss SMT GmbH, PANalytical, TNO, as well as the Province of Overijssel and the Foundation NWO.

Literature

1.Shiou-Min Wu, et. al, J. App. Phys., 106, 2009 2.E. Cattaruzza, et.al., Appl. Surf. Sci., 320, 2014

Abstract

Energetic Particles above sputter threshold are capable of inducing damage either by recoil generation or through compound formation. This is studied as a basis for future work by irradiation of a metal coated quartz crystal microbalance (QCM) to Ar+ _ions

and a mixture of N+_/N

2+ ions. Frequency changes of QCM were used to measure the thickness loss or gain for sputtering or compound

formation induced implantation respectively. Nitrogen ions were found to implant resulting in a nitride.

∆𝑧𝑧 = 𝑁𝑁_{𝜋𝜋𝜋𝜋𝜋𝜋𝜋𝜋 𝑡𝑡𝑡𝑡𝑡𝑡}𝑄𝑄𝑑𝑑𝑄𝑄 −1 𝜋𝜋𝑡𝑡𝑡𝑡𝑡𝑡 𝜋𝜋 𝜋𝜋0_𝜋𝜋− 𝜋𝜋

0

× 0.1 (𝑡𝑡𝑛𝑛)

𝑌𝑌𝑌𝑌𝑌𝑌𝑌𝑌𝑑𝑑 = _𝑀𝑀∆𝑧𝑧 × 𝜋𝜋 × 𝑌𝑌

𝑡𝑡𝑡𝑡𝑡𝑡 × 𝐽𝐽𝑖𝑖𝑖𝑖𝑖𝑖 × 𝑡𝑡

From Sauerbrey’s equation:

• Sputter Yield from Argon obtained as reference and compared to literature[1]. E_th: 37eV

• Lower yield from Nitrogen bombardment suspected to occur due to higher surface binding energy of formed nitride.

• XPS show implantation with possible formation of ruthenium nitride/oxy-nitride [2] 𝑁𝑁_𝑞𝑞 = 1.668 × 1013 𝐻𝐻𝑧𝑧 𝐴𝐴𝐴 𝑑𝑑_𝑄𝑄 = 2.648 𝑔𝑔/𝑐𝑐𝑛𝑛3 𝜋𝜋 = 𝐴𝐴𝑐𝑐𝐴𝐴𝐴𝐴𝐴𝐴𝑡𝑡𝑌𝑌𝑐𝑐 𝐼𝐼𝑛𝑛𝐼𝐼𝑌𝑌𝑑𝑑𝑡𝑡𝑡𝑡𝑐𝑐𝑌𝑌 𝑅𝑅𝑡𝑡𝑡𝑡𝑌𝑌𝐴𝐴 𝜋𝜋 = 12.37𝑔𝑔/𝑐𝑐𝑛𝑛3 𝜋𝜋₀ = 6 × 106𝐻𝐻𝑧𝑧

Quartz cleaned with 300eV Ar+ after each nitrogen exposure

Base Pressure: 1x10-8 _mbar

Working Pressure: 0.5 - 1 x10-4 _mbar

𝑁𝑁₂ + 𝑌𝑌− 𝜎𝜎1𝑒𝑒𝑖𝑖 𝑁𝑁₂+ 𝑁𝑁₂+ + 𝑁𝑁₂ + 𝑁𝑁₂ 𝑘𝑘1𝑒𝑒𝑖𝑖 𝑁𝑁₄+ + 𝑁𝑁₂ 𝑁𝑁 + 𝑌𝑌− 𝜎𝜎2𝑒𝑒𝑖𝑖 𝑁𝑁+ 𝑁𝑁₂ + 𝑌𝑌− 𝜎𝜎𝑒𝑒𝑑𝑑 2𝑁𝑁 𝑁𝑁₂+ + 𝑌𝑌_𝑝𝑝 𝑘𝑘2𝑒𝑒𝑖𝑖 𝑁𝑁 + 𝑁𝑁 Plasma Processes

Thermion induced processes