Search

This work reports the characterization of the interface amorphous carbon (a-C)/SiO2 by neutron and X-ray reflectometry. Neutrons have shown the existence of an intermediate layer (IL) between the a-C and the SiO2 layers that was not evidenced by XRR. This IL has been associated with the accumulation of H inside the SiO2 layer near the interface with the a-C. The characteristics of this layer, in particular, its H-concentration and thickness, seem to be correlated with the weakness of this interface. A plot of the molecular weight as a function of the mass density for the SiO2 and the IL layers graphically demonstrates the risk of delamination of each sample. The combination of NR and XRR is shown to be a powerful technique in the characterization of layers and interfaces used in the micro/nanoelectronics industry. The same approach can be extended to other interfaces of interest involving hydrogen.

In this paper, we investigate the tendency of porous low-K dielectrics (also named Ultra Low-K, ULK) behavior to shrink when exposed to the electron beam of a scanning electron microscope. Various experimental electron beam conditions have been used for irradiating ULK thin films, and the resulting shrinkage has been measured through use of an atomic force microscope tool. We report the shrinkage to be a fast, cumulative, and dose dependent effect. Correlation of the shrinkage with incident electron beam energy loss has also been evidenced. The chemical modification of the ULK films within the interaction volume has been demonstrated, with a densification of the layer and a loss of carbon and hydrogen elements being observed.

Thin TaN metallic barriers are used to prevent copper diffusion into porous low-k dielectrics such as a-SiOC:H for advanced interconnects. We investigate the detailed electronic properties of the TaN/a-SiOC:H stack. Here we combine ultraviolet and x-ray photoelectron spectroscopy to measure the chemical composition and the whole band diagram of the TaN/a-SiOC:H stack. An original interpretation based on the image-force model used for internal photoemission is suggested to explain the electric field effect induced by negative bias of a-SiOC:H. This model is used to extrapolate the unbiased electron affinity of the dielectric. TaN work function, a-SiOCH band gap, valence band maximum and electron affinity of 4.6, 7.7, 4.0, and 3.8 eV are respectively obtained. Kelvin force microscopy and spectroscopic ellipsometry confirm TaN work function and a-SiOC:H band gap measurements, respectively. From the full band diagram of the TaN/a-SiOC:H stack, an interfacial barrier height of 0.8 eV is deduced.

The down scaling of complementary metal oxide semiconductor transistors requires materials such as porous low-k dielectrics for advanced interconnects to reduce resistance-capacitance delay. After the deposition of the matrix and a sacrificial organic phase (porogen), postcuring treatments may be used to create porosity by evaporation of the porogen. In this paper, Auger electron spectroscopy is performed to simultaneously modify the material (e-beam cure) and measure the corresponding changes in structure and chemical composition. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy measurements in attenuated total reflection mode confirm the Auger results. The porogen removal and matrix cross-linking result in the formation of a Si–O–Si network under e-beam or ultra violet cure. The possible degradation of these materials, even after cure, is mainly due the presence of Si–C bonds.