Wei-jen Hsia

Copper drift in methyl-doped silicon oxide film

Drift of copper (Cu) ions into methyl-doped silicon oxide film, a promising low-dielectric-constant (low-κ) material for inter-layer dielectrics applications in ultralarge scale integrated circuit (ULSI) interconnects, was investigated using bias temperature stressing (BTS)/capacitance–voltage (C–V), current–voltage (I–V) at elevated temperatures and time-dependent dielectrics breakdown (TDDB) tests. Standard and control metal–insulator–semiconductor capacitor test samples with “sandwich” dielectric layer structures were used in the tests. BTS in nitrogen (N2) ambient at an electric field magnitude up to 1.5 MV/cm and with temperatures between 175 and 275 °C was used to accelerate the Cu ion drift. By studying flat band voltage shift in C–V tests, leakage current magnitude in I–V tests and time to fail in TDDB tests, it is demonstrated that Cu ions readily drift into methyl-doped silicon oxide under electric fields at elevated temperatures. Results obtained using different techniques correlate well to eac...

Chemical Mechanical Polishing of Low Dielectric Constant Oxide Films Deposited Using Flowfill Chemical Vapor Deposition Technology

In this work, the properties and chemical mechanical polishing (CMP) characteristics of thin films of a new low dielectric constant (low-κ) oxide deposited using Flowfill chemical vapor deposition (CVD) technology are presented. This oxide film consists of silicon dioxide network with methyl groups incorporated and has a dielectric constant K as low as ∼2.7. The film properties were studied using Fourier transform infrared spectroscopy (FTIR), spectroscopic ellipsometry, Rutherford backscattering, atomic force microscopy, and capacitance-voltage measurements. The refractive index, as low as 1.38, was measured using spectroscopic ellipsometry. The surface was found to be more hydrophobic compared to conventional CVD oxide. The stretching mode of the Si-O bond peak in the FTIR spectrum shifts to lower wavenumber, which corresponds to lower Si-O bonding energy, with increase in the methyl concentration inside the film. The CMP removal rate decreases as the methyl concentration in the film increases. An atomically smooth surface with root mean square surface roughness <1 nm over an area 2 X 2 μm was obtained after CMP. Our results suggest that the incorporation of methyl groups results in a reduction in the CMP removal rate. We speculate that the diffusion of water into the film is probably the CMP removal rate-limiting step.

Characterization of methyl-doped silicon oxide film deposited using Flowfill™ chemical vapor deposition technology

In this article, methyl-doped silicon oxide films deposited using Flowfill™ chemical vapor deposition (CVD) technology have been chracterized for use in inter-layer dielectrics application. Films with different methyl concentrations were deposited and characterized in order to study the effect of methyl concentration on film properties. Material properties including chemical composition and bonding structure, density, dielectric constant (κ), refractive index, thermal stability, resistance to moisture absorption, leakage current, and hardness were investigated. The films have a κ as low as 2.7 and were found to be thermally stable up to 550 °C. They show excellent resistance to moisture absorption. Low-leakage current and breakdown voltage higher than 3 MV/cm were obtained. Their hardness is lower than silicon oxide deposited using plasma-enhanced CVD but is higher than most polymer and nanoporous low-dielectric constant (low-κ) materials. The chemical mechanical polishing (CMP) characteristics of these f...

Deposition and Characterization of Polycrystalline Si1 − x Ge x Films for CMOS Transistors Gate Electrode Applications

Polycrystalline Si 1 - x Ge x (poly-SiGe) is a known gate electrode material that can mitigate poly-depletion effects, which exist in deep submicrometer complementary metal-oxide-semiconductor (CMOS) transistors, due to its lower dopant activation temperatures and smaller bandgaps. As an important step toward the manufacturing of poly-SiGe electrode-based CMOS transistors with enhanced performances, this study focuses on the deposition of poly-SiGe films with different structural features and the characterization of the physical properties of these films. The electrical performance and the reduction in poly-depletion effects of the poly-SiGe electrodes in capacitors fabricated using these films were verified using capacitance-voltage measurements.