In situ investigations of the chemical and mechanical mechanisms during CMP processes require analytical access to the wafer surface while interacting with the slurry and the pad under polishing conditions. In this study me make use of novel, specifically prepared, and self-designed Si wafer called microstructured single reflection elements (mSRE) utilizing the IR transparency of silicon [1]. The mSRE's enable in and ex situ attenuated total reflection (ATR) Fourier transform infrared (FTIR) investigations at the interface between silicon and the ambient with an enhanced usable spectral range. So, a thin silicon oxide layer or the polishing slurry can be investigated in the entire mid and far infrared spectral region. These mSRE wafers were placed at a simple reflection accessory of a FTIR spectrometer and either wet etched by a buffered oxide etch or polished using a CMP equivalent polishing configuration. During CMP the change of typical vibration bands of SiO 2 layers and slurry constituents are observed. It was shown that the sensitivity as well as the surface selectivity of the experimental setup enables slurry and thin-film characterisations within the thickness range of monolayers. Surprisingly, the spectral features of the pad have not been observed during the polishing investigations.

A new recording technique for the measurement of infrared spectra of powders using ATR spectroscopy is presented in this paper. The method, called ATRIMS (attenuated total reflection immersion medium spectroscopy), circumvents some ofthe problems of conventional methods. With ATRIMS, an ATR reflection element is covered with a thin film of liquid paraffin (Nujol) as an immersion medium for the powder. Compared to ATR spectroscopy of dry powders on the surface of a reflection element, ATRIMS shows higher band intensities, lower detection limits, reduced necessary sample amount, easier handling, and shorter analysis time. The resulting spectra have the typical band intensity-wavelength relationship of ATR spectra. The method is well suited for the investigation of strong absorbing substances (e.g. magnetite) and strong scattering substances (e.g. hydrargillite).

In this study, the effect of the addition of electrolytes in a given ionic strength to various high-purity silica suspensions was investigated by measurement of the removal rates (RR's) in CMP processes on oxide layers under the same experimental conditions. As so-called slurries the following suspensions were used: i) silica sols produced by the Stöber process, ii) conventional silica sols based on alkali silicate as well as iii) suspensions of fumed silica, with the same SiO2 concentration in each suspension. Ionic strength of the added electrolyte was adjusted to e.g. 0.065 mol/l, with the electrolytes being HCl, NH4Cl, KOH, or binary mixtures of these substances.These investigations revealed significant differences of the polishing behaviour between the different types of silica dispersions as slurries. While for the Stöber sols investigated, the RR's are highest in the acidic range and almost negligible in the alkaline pH range, fumed silica suspensions show an entirely different behaviour: RR is very low for acidic pH-values, and increases with the alkalinity of the slurry. In contrast to these observations, the RR's of slurries based on conventional silica sols are highest around the neutral point, and show a decrease for both more alkaline and acidic pH-values. In comparison to the other two types of material, these suspensions have a high amount of electrolyte background, originating from their manufacturing process.A model is developed to explain these results in a comprehensive manner. It involves effects of the electrolyte type and the ionic strengths as well as influences of the particle size.