Nanoparticle removal obtained without inflicting damage to fragile device elements remains a big challenge. The feasibility of physical cleans is assessed and boundary conditions are outlined. An overview of megasonic cleaning process improvements is given. In order to reduce damage without reducing particle removal frequencies during high frequency ultrasound cleaning processes, cavitation needs to be better controlled. This is partly achieved by (1) using pulsed acoustic fields which makes it possible to control the average bubble size and, at the same time, maximize the number of resonant bubbles, by (2) increasing the dissolved gas concentration and lowering the surface tension which facilitates bubble formation and, finally, by (3) introducing traveling waves to transport bubbles to the surface which needs to be cleaned.

In this paper, the Faddeev-Jackiw approach is improved by the Wu elimination method, so a great many complicated computations in solving constraints for the finite-dimensional polynomial-type constrained dynamics can be executed easily by using computers. Moreover, based on the Faddeev-Jackiw approach, a new algorithm of solving the constrained dynamics is presented. The new algorithm is simpler and stricter than the Faddeev-Jackiw approach. Using the new algorithm, the second Cawley counterexample is solved.

Interconnect solutions for advanced technology nodes using PECVD techniques for low-k deposition require the use of porogen-based process with post deposition UV cure. By using two different UV cure lamps (A, B) in combination with different porogen loads, three different micro-porous low-k films are developed: Aurora ELK HM (k~2.5; porosity (P) ~25%), Aurora ELK A (k~2.3; P~34%) and Aurora ELK B (k~2.2; P~37%). Integrating these materials is complex and challenging. We discuss key factors that are instrumental to the extension of a metal hard mask (MHM)-based integration scheme to these 3 low-k films. Our findings: (I) for sub-100nm dimensions, patterning and low-k interactions affect the dynamic of organic residue formation and thereby impact electrical yield; (II) choosing the right ash, etch and clean sequence is mandatory to control plasma damage, profile, residues and corrosion on top of the MHM; (III) Cu reduction plasmas must be adjusted when porosity is increased to mitigate field damage.

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Influence of surface tension on cavitation noise spectra and particle removal efficiency in high frequency ultrasound fields, Journal of Applied Physics, 112(11). Archived versionFinal publisher's version / pdf Influence of surface tension on cavitation noise spectra and particle removal efficiency in high frequency ultrasound fields Physical cleaning methods are applied in the semiconductor industry and have become increasingly challenging due to the continued scaling of semiconductors device elements. Cavitation and acoustic phenomena are known to play a fundamental role in megasonic cleaning. Hence, a better understanding of cavitation phenomena in multi-bubble systems is crucial. Here, a study on the effects of lower bulk surface tension and different O 2 concentrations on the bubble activity in the megahertz range is presented. A lower bulk surface tension (45 mN/m) with respect to ultra pure water (72 mN/m) is obtained by adding a non-ionic surface-active agent (Triton X-100). After a thorough surfactant characterization, a Triton X-100-containing cleaning solution is investigated under pulsed and continuous acoustic fields, for different acoustic amplitudes and gas concentrations. It is demonstrated that cavitation activity, measured by means of ultraharmonic cavitation noise, is enhanced in presence of a lower surface tension, under continuous acoustic fields. In addition, cavitation measurements performed under pulsed fields reveal the existence of optimal pulse-off times, for which a maximum of activity is observed. These optimal pulse-off time values are linked to the bubble dissolution theoretical times and experimentally verified. To end, cavitation noise measurements are correlated to cleaning performance in megasonic fields by means of particle removal and damage tests on patterned wafers. A clear increase in particle removal efficiency of 78 nm SiO 2 particles is obtained when Triton X-100 is employed, at the optimized process conditions. In addition, the number of defects due to cavitation bubbles is significantly reduced for lower surface tension, at particle removal efficiencies <60%. The results here reported constitute a different approach towards more efficient megasonic cleaning processes.