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We report a new curing procedure of a plasma enhanced chemical vapor deposited SiCOH glasses for interlayer dielectric applications in microelectronic. It is demonstrated that SiOCH glasses with improved mechanical properties and ultralow dielectric constant can be obtained by controlled decomposition of the porogen molecules used to create nanoscale pores, prior to the UV-hardening step. The Young’s modulus (YM) of conventional SiOCH-based glasses with 32% open porosity hardened with porogen is 4.6 GPa, this value is shown to increase up to 5.2 GPa with even 46% open porosity, when the glasses are hardened after porogen removal. This increase in porosity is accompanied by significant reduction in the dielectric constant from 2.3 to 1.8. The increased YM is related to an enhanced molecular-bridging mechanism when film is hardened without porogen that was explained on the base of percolation of rigidity theory and random network concepts. [ABSTRACT FROM AUTHOR]

Atomic layer deposition (ALD) of tungsten carbide nitride (WC[sub 0.7]N[sub 0.3]) on a low-k (dielectric constant) dielectric aromatic polymer material is investigated. It is feasible to deposit thin WC[sub 0.7]N[sub 0.3] films on polymers, but applying a nitrogen–oxygen (N[sub 2]–O[sub 2]) based plasma to the surface prior to ALD can significantly enhance the growth. The creation of polar surface groups by the plasma treatment is derived from the water contact angle and from O 1s to C 1s peak ratio extracted from x-ray photoelectron spectroscopy. Rutherford backscattering spectra and contact angle measurements revealed a typical ALD growth with at least two successive regimes. The first is controlled by the substrate surface, while during the last a constant amount of ALD material is added with each cycle. The plasma treatments create adsorption sites on the surface and therefore effectively enhance the growth and shorten the duration of the first regime. This observation is attributed to an improved initial ALD precursor adsorption. However, ALD island formation on the treated polymer is not merely a function of the number of available adsorption sites but depends also on the structure and composition of the substrate surface. The minimum thickness of a continuous ALD film is ∼10 nm on untreated polymer while on top of a N[sub 2] rich reactive ion etch plasma-treated polymer the WC[sub 0.7]N[sub 0.3] film becomes continuous between 1.4 and 2.3 nm. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The ever increasing requirements for electrical performance of on-chip wiring has driven three major technological advances in recent years. First, copper has replaced Aluminum as the new interconnect metal of choice, forcing also the introduction of damascene processing. Second, alternatives for SiO[sub 2] with a lower dielectric constant are being developed and introduced in main stream processing. The many new resulting materials needs to be classified in terms of their materials characteristics, evaluated in terms of their properties, and tested for process compatibility. Third, in an attempt to lower the dielectric constant even more, porosity is being introduced into these new materials. The study of processes such as plasma interactions and swelling in liquid media now becomes critical. Furthermore, pore sealing and the deposition of a thin continuous copper diffusion barrier on a porous dielectric are of prime importance. This review is an attempt to give an overview of the classification, the characteristics and properties of low-k dielectrics. In addition it addresses some of the needs for improved metrology for determining pore sizes, size distributions, structure, and mechanical properties. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The deposition of homogeneous thin films on porous substrates has been investigated. The thin film deposition of Ta(N) by physical vapor deposition on porous films with different average pore sizes and material compositions has been studied. The continuity of Ta(N) films on top of porous low-k dielectrics is evaluated by means of ellipsometric porosimetry combined with sheet resistance and atomic force microscopy measurements. Interface reactions are analyzed by x-ray photoelectron spectroscopy profiling. It has been observed that the minimal Ta(N) thickness required to obtain a continuous metal layer on top of the porous film depends, on the one hand, on the porosity and pore size and, on the other hand, on the chemical interaction of the thin film with the porous substrate. The sealing of pores is favored by the presence of carbon in the dielectric matrix. This is explained through a mechanism of local enhancement of the degree of crosslinking in the dielectric matrix, catalyzed by Ta. [ABSTRACT FROM AUTHOR]

A spectroscopic ellipsometry (SE) model was developed and implemented to study substrate loss in shallow implanted silicon (i-Si) substrates following a photoresist strip. The model is based on different optical properties of silicon dioxide (SiO,) and i-Si layers and silicon substrates and is used to characterize relevant layers, i-Si and SiO2, before and after plasma treatment. An increase in SiO2 and a decrease in the i-Si layer were observed after plasma exposure. Changes in the i-Si layer are the result of two phenomena, oxidation and heating-induced regrowth of the i-Si layer, while changes in the SiO2 thickness represent the direct measure of substrale loss due to oxidation. Transmission electron microscopy (TEM) and secondary-ion mass spectrometry (SIMS) analysis were performed to cross-check the validity and accuracy of the SE model. The TEM results confirm that the SE model can distinguish between a crystalline (c-Si) substrate and an i-Si layer regardless if the i-Si is damaged, crystalline, or amorphized. There is also good consistency between the SE and SIMS results. For the plasma processes studied in this work, minimal changes in layer thicknesses and substrate losses measured by SE agree very well with the measured SIMS dopant profiles. [ABSTRACT FROM AUTHOR]

In this study, the effect of the sequential He and NH3 plasma treatments on a chemical vapor deposition SiOC:H low-k dielectric is evaluated in the wide range of experimental conditions. Results show that the active NH3 plasma radicals penetrate the porous low-k bulk and remove the hydrophobic Si-CH3 groups, which leads to hydrophilization and results in the degradation of dielectric properties. The implementation of He plasma pretreatment reduces the damage imposed by the NH3 plasma by a stimulation of the surface recombinatiori of active radicals from NH3 plasma. He plasma causes a surface modification of 10-20 nm presumably due to the energy transfer from the extreme UV photons and the 21S He metastable atoms to the low-k structure. The plasma damage reduction is proportional to He plasma density and the treatment time. The mechanism of plasma damage reduction is explained on the basis of the Knudsen diffusion mechanism and random walk theory. [ABSTRACT FROM AUTHOR]

Plasma damage of SiCOH low-k films in an oxygen plasma is studied using a transformer coupled plasma reactor. The concentration of oxygen atoms and O2+ ions is varied by using three different conditions: (1) bottom power only, (2) bottom and top power, and (3) top power only. After plasma exposure, the low-k samples are characterized by various experimental techniques. It is shown that the ion bombardment induced by the bottom power minimizes the plasma damage by increasing the recombination coefficient of oxygen radicals. Contrary to the expectations, the densification of the top surface by ion radiation was limited. The increase in the recombination coefficient is mainly provided by modification of the pore wall surface and creation of chemically active sites stimulating the recombination of oxygen atoms. The results show that a reduction in plasma damage can be achieved without sealing of low-k top surface. [ABSTRACT FROM AUTHOR]

Continuous downscaling of integrated circuits brought an end to the era of SiO2. In gate dielectrics, it is being replaced by materials with high dielectric constant, so-called high-k dielectrics. One of the challenges in the integration of the high-k material is removal of those materials selectively over the substrate. This work is one of the first attempts to review current state of the art of the high-k removal. Two main approaches are discussed: dry (plasma) removal and wet removal. First, the fundamentals and limitations of both approaches are presented, then an overview of the existing experimental data is given. It is concluded that the best results could be obtained by combining the dry and wet approaches. [ABSTRACT FROM AUTHOR]

Titanium nitride (TiN) is widely used in metal gate applications. Exposing TiN to a Cl2/HBr plasma results in pronounced surface roughness that can be easily characterized by ellipsometry. The ellipsometric angle Δ is proportional to the roughness if the roughness does not exceed 30 nm. It is possible to plot a "roughness diagram" where a border can be drawn between the smooth and rough etch surfaces depending on the etch conditions. This diagram could be used for gate-etch process optimization. In our case, the roughness could be overcome by increasing HBr content and/or substrate bias during the etching. [ABSTRACT FROM AUTHOR]

A study of the impact of physical vapor deposition conditions on the etch properties of TiN has been conducted using a transformer coupled plasma. This work focuses only on a Cl2-based etch plasma. It is shown that the crystallographic orientation of TiN, observed from x-ray diffraction spectra, has a major influence on the etch behavior. Etch yields at varying dry etch conditions of two types of TiN, with different crystallographic orientations, have been studied quantitatively. The high roughness which is created during plasma exposure was identified as being the result of different etch rates of grains and intergranular material at the grain boundaries. Moreover, it is shown that TiN(111) is more difficult to etch, resulting in more pronounced roughness, than TiN(200), which is easier to etch, resulting in smoother surfaces for certain process conditions. [ABSTRACT FROM AUTHOR]