Polymer coated silicon wafer

Project of Nurshahidah Ali (Technology Development School of Applied Science, Temasek Polytechnic)

Analysis of nanometers-thick layers placed on silicon substrate has been unfeasible task for FTIR spectroscopy for many years. Traditional FTIR sampling techniques such as transmission or ATR typically measure samples or coatings on samples where the thickness is 3 orders of magnitude greater. Grazing angle reflection techniques have been used successfully to measure monomolecular layers on reflective substrates. However, in the case where silicon is the substrate, the reflection spectrum contains the signature of the base material in addition to the monolayer and resolving the distinctive features of the surface film becomes difficult. Monolayers and nanometers-thick films absorbed on silicon are easily sampled using the VeeMAX II - now available at ISMI beamline. VeeMAX II offers continuous variable angle of incidence (in the range from 30 to 80 degrees) and a variety of crystal plates to selectively control the depth of penetration of the IR beam; its high throughput provides excellent sensitivity and reduced sampling time. Very thin (20 nm) polymeric films have found many applications in different industries. More recently, their use in the biomedical field is gaining considerable interest because they offer great versatility in the chemical groups that can be incorporated at the surface. The constraints imposed by the surface also allow for unique physical properties not usually observed for the bulk polymer. In this study performed by Researchers from Technology Development School of Applied Science (Temasek Polytechnic), T-structure polydimethylsiloxane (T-PDMS) and polystyrene (PS) were characterized by synchrotron-based FTIR spectroscopy. VeeMAX II equipped with high refractive index ATR crystal (Ge) and pressure clamp was inserted in a sample compartment of Bruker spectrometer IFS 66v/S. The angle of incidence of the IR beam was set to 600 with respect to the normal plane of the ATR crystal.