No abstract

This study investigated the effect of different pad surface micro-textures on the tribological, thermal and kinetic attributes during copper chemical mechanical planarization (CMP). Different micro-textures were generated by two different chemical vapor deposited (CVD) diamond-coated conditioner discs (i.e. Disc A and Disc B). Results showed that while pad temperature and removal rate increased with polishing pressure and sliding velocity on both discs, Disc B generated consistently lower removal rates and coefficients of friction (COF) than Disc A. To fundamentally elucidate the cause(s) of such differences, pad surface contact area and topography were analyzed using laser confocal microscopy. The comparison of the pad surface micro-texture analysis indicated that Disc A generated a surface having a smaller abruptness (λ) and much more solid contact area which resulted in a higher removal rate. In contrast, Disc B generated less contact areas and COF. A two-step modified Langmuir–Hinshelwood model was employed to simulate copper removal rates as well as chemical and mechanical rate constants. The simulated chemical to mechanical constant ratios indicated that Disc A produced a more mechanically limited process under all of the polishing conditions tested.

This study investigated the effect of two conditioner discs (i.e. “Disc A” and “Disc B”) during tungsten chemical mechanical planarization. Results showed that while pad temperature and removal rate increased with polishing pressure and platen velocity on both discs, “Disc B” generated consistently lower removal rates and coefficients of friction than “Disc A”. To fundamentally elucidate the cause(s) of such differences, pad surface contact area and topography were analyzed using laser confocal microscopy. The comparison of the pad surface micro-texture analysis on pad surfaces conditioned by both discs indicated that “Disc A” generated a surface having a smaller abruptness (λ) and more solid contact area which resulted in a higher removal rate. In contrast, “Disc B” generated many large near-contact areas as a result of fractured and collapsed pore walls.

Semiconductor/metal composite nanomaterials have been used as surface-enhanced Raman scattering (SERS) active substrates and have attracted increasing attention due to their widespread applications in both optical and material fields. Here, we report a facile strategy to prepare highly sensitive SERS substrates with excellent reproducibility and stability based on uniform and well-controlled Ag nanoparticle (NP) decorated Cu 2 O nanoframes. Our strategy is a unique one-pot procedure. Simply, hollow Cu 2 O/Ag composite nanoframes (Cu 2 O/Ag CNFs) with tunable silver content have been successfully designed and constructed by reduction of Ag + with sodium citrate in a 14 day old Cu 2 O-containing mother solution, and then a second component (Ag) was directly deposited onto primary nanomaterials (Cu 2 O nanoframes).There is an optimum amount of Ag NPs. When 0.40 mM AgNO 3 is used, the prepared Cu 2 O/Ag CNFs show significantly improved SERS properties with an enhancement factor of ~10 5 . Furthermore, the enhancement mechanism, reproducibility and stability of Cu 2 O/Ag CNFs are investigated in detail. The excellent properties of the prepared Cu 2 O/Ag CNFs suggest that this substrate has a potential application in SERS detection.

Slurry mean residence time, dispersion number, removal rate, coefficient of friction, and pad temperature were analyzed for standard pad center area slurry application and two configurations (“Design A” and “Design B”) of the novel slurry injection system (SIS) used in chemical mechanical planarization. The novel SIS was placed on the pad surface and slurry was injected through an inlet port which matched an outlet at the trailing edge of the injector bottom. SIS having “Design A” has flat leading edge to prevent, as much as possible, spent slurry or residual water from re-entering the pad-wafer interface. In contrast, “Design B” possesses several notches on its leading edge for the temporary accumulation of a small amount of spent slurry. Results showed both configurations of the novel SIS generated lower coefficient of friction and pad temperature, shorter slurry mean residence time, smaller dispersion number and higher removal rate than the standard pad center area slurry application method. “Design B” has a higher mean residence time and larger dispersion number than “Design A” since “Design B” allows more spent slurry/residual rinse water to re-enter the pad-wafer interface than “Design A”. This work underscores the importance of slurry injection method for achieving optimum chemical mechanical planarization processes.