Unusual energy shifts in resonant photoemission spectra of organic model molecules.

We study the electronic structure of zinc phthalocyanine (ZnPc) and 1,4-octa-decyl substituted zinc phthalocyanine [(Dec)(8)PcZn] thin films (approximately 6-15 nm) using resonant photoemission spectroscopy and X-ray absorption spectroscopy (XAS) at room temperature and at liquid He temperature. From XAS we conclude that the probability amplitude of the lowest unoccupied molecular orbital is located predominantly at the inner C and N atoms of the molecules. Nonlinear energy shifts in resonant photoemission were observed; large shifts are explained by reduced electrical conductivity of inhomogeneously oriented molecules.

Characterization of the morphology and composition of commercial negative resists used for lithographic processes.

We present a spectroscopic and microscopic characterization of the chemical composition, structure, and morphology of two commercial negative resists using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). For this purpose, films of a novolak-based resist (ma-N 2400) and hydrogen silsesquioxane (HSQ) are treated under different conditions (temperature, deep ultraviolet (DUV) exposure, CHF(3) plasma). Topographic AFM images show that both heating and DUV exposure strongly affect the surface morphology of as-prepared ma-N 2400 resist films. These different treatment conditions also lead to decreasing roughnesses, which indicates structural reorganization. Furthermore, the decrease of the photoactive compound (bisazide) in the ma-N 2400 resist films, observed in FTIR spectra, suggests cross-linking of the resist after CHF(3) plasma treatment, heating, or DUV exposure. XPS measurements on different CHF(3) plasma-treated surfaces reveal that a structurally homogeneous fluorine-containing polymer is generated that is responsible for an enhanced etch resistance. FTIR measurements of HSQ films show a correlation between the degree of HSQ cross-linking and baking time.

Tetra-t-butyl magnesium phthalocyanine on gold: electronic structure and molecular orientation.

In this work we have investigated the electronic structure and the molecular orientation of (t-Bu)(4)PcMg (tetra-t-butyl magnesium phthalocyanine) on polycrystalline and single crystalline gold substrates using photoemission spectroscopy and x-ray absorption spectroscopy, and we compare the results to the unsubstituted PcCu (copper phthalocyanine). The C 1s photoemission spectrum is described similar to unsubstituted relatives with an additional component for the aliphatic substituents. The variation of the excitation energy causes distinct differences in the shape of the C 1s spectrum, which is very useful for the analysis of the molecular orientation in the uppermost layer. It is shown that despite of the sterically demanding substituents, ordered sublimed films of (t-Bu)(4)PcMg are accessible, the orientation of the molecules, however, is different from the orientation of the unsubstituted relatives.