Effect of duty ratio of patterned surface on planarization by gas cluster ion beams

Abstract

We studied the effect of the duty ratio, i.e., the ratio of hill width to pitch, of patterned diamondlike carbon (DLC) surfaces on Ar gas cluster ion beam (GCIB) planarization effect. The patterns of 40 nm depth were fabricated on Si substrates by electron beam lithography and CHF 3 reactive-ion etching. The pitch of the line-and-space pattern was 300 nm and three duty ratios were adopted. Then, refilling materials were deposited to 50 nm thickness on the patterned substrates. The test samples were irradiated by Ar-GCIB and the resultant surface profiles were measured by atomic force microscopy. The acceleration energy for one cluster was 20 keV. The dose was set in the range from 5Â10 14 to 5Â10 16 ion/cm 2 . Although there was a difference in the dose, the patterns clearly disappeared upon irradiating GCIB. The reduction rate of the peak-to-valley height decreased as the width of the hill increased. We indicated that GCIB irradiation is effective for the planarization of patterned surfaces with various duty ratios.

Non-lift-off Block Copolymer Lithography of 25 nm Magnetic Nanodot Arrays

“…A naïve view would suggest that Ar ion beam milling at normal incidence would maintain this conformal pattern through the entire milling process, yielding no pattern transfer to the NiFe layer. However, because of effects such as resputtering occurring within the dimple features, planarization of the surface occurs (a well-documented phenomenon − ). By 15 min of milling (Figure b) more than 80% of the dimples are no longer visible with the remainder being considerably shallower than in the original overlayer (Figure a), as indicated by the weaker contrast and smaller diameter in AFM and SEM images.…”

White light interferometry for quantitative surface characterization in ion sputtering experiments

“…Another important application of the WLI method to sputter depth profiling is exemplified by the sputtering time to sputtered depth calibration procedure applied to this particular experiment. The samples analyzed here were pieces of Si(001) wafer implanted with 25 Mg + , 44 Ca + and 53 Cr + ions at energy of 1 keV per atomic mass unit (25 keV for 25 Mg, 44 keV for 44 Ca and 53 keV for 53 Cr, all at 3×10 13 ions/cm 2 fluence) fabricated by Leonard Kroko Inc. A TOF MS analysis of these samples was performed by laser post-ionization of sputtered neutrals (secondary neutral mass spectrometry, SNMS) using resonantly enhanced multi-photon ionization to simultaneously detect all isotopes of Mg, Ca and Cr [23]. This was an experiment on sputter depth profiling which started in the DB mode as described above but, after the concentration peaks of the implants were passed (that is, after 170 nm on the depth scale in Fig.…”

“…In this example, the depth resolution of the WLI technique applied to characterization of Si surfaces irradiated with gas cluster ion beams (GCIB) is demonstrated. The GCIB in these sputtering experiments was an argon cluster beam Ar + N with N =2000, where N corresponds to the number of atoms in the peak distribution and, in general, can lie between 200 and 10000 [24,25]. Irradiating materials surfaces with such cluster ions causes two unique 25 Mg (wine circles), 44 Ca (green squares), 53 Cr (blue diamonds) implanted in Si host matrix at 1 keV per nucleon (1 keV/amu).…”

“…The GCIB in these sputtering experiments was an argon cluster beam Ar + N with N =2000, where N corresponds to the number of atoms in the peak distribution and, in general, can lie between 200 and 10000 [24,25]. Irradiating materials surfaces with such cluster ions causes two unique 25 Mg (wine circles), 44 Ca (green squares), 53 Cr (blue diamonds) implanted in Si host matrix at 1 keV per nucleon (1 keV/amu). Lines (red, light green and gray) are independent TRIM simulations of depth distributions for the same isotopes of 1keV/amu energies in SiO2/Si sandwich (SiO2 thickness is of 2 nm) effects.…”

“…FIG.4: Symbols represent measured secondary neutral massspectrometry depth profiles of isotopes25 Mg (wine circles), 44 Ca (green squares), 53 Cr (blue diamonds) implanted in Si host matrix at 1 keV per nucleon (1 keV/amu). Lines (red, light green and gray) are independent TRIM simulations of depth distributions for the same isotopes of 1keV/amu energies in SiO2/Si sandwich (SiO2 thickness is of 2 nm)…”