Investigation of adsorption and dissolution using quartz crystal microbalance (QCM) techniques: Application to semiconductor cleaning and polishing

The adsorption of selected surfactants and inorganic ions of interest to semiconductor processing onto metallic, semiconductor, and dielectric surfaces has been investigated using a quartz crystal microbalance (QCM) technique. The effects of variables such as solution pH and concentration on the extent of adsorption have been characterized. Improvement of the sensitivity of the technique using an electrical bias to the crystal electrode has been explored. The etch rate of sputter coated silicon, sputter coated silica, and thermally grown silica of interest to semiconductor processing has been investigated using a thickness shear mode (TSM) quartz crystal microbalance (QCM) technique. In this research, silicon and sputtered silica and low temperature thermal oxide were investigated in ammonia peroxide solutions using a quartz crystal microbalance. The results obtained have been compared with the literature results to show that a QCM is a valuable in situ measurement technique to follow low levels of etch rate. In an application of the QCM technique to the chemical mechanical polishing (CMP) process, the static etch rate and chemical mechanical polishing rate of an Al-1%Si-0.5%Cu alloy were investigated in abrasive-free solutions containing a proprietary amine at alkaline pH values. The effect of lixiviant, oxidizing agents, complexing agents, temperature, and applied pressure on polishing behavior were investigated. The results have shown that it is possible to polish aluminum alloy films with a high degree of selectivity over SiO2 using abrasive-free amine based solutions containing a glycine based complexing agent