The effects of chemical mechanical planarization ͑CMP͒ process parameters and consumables on the polish rate and defects generated in various low-k materials with k values ranging from 2.2 to 3.0 were studied in detail. The process consumables and conditions evaluated include slurry material ͑alumina and silica͒, pad type ͑soft and hard͒, polish pressure, and polish time. Atomic force microscopy ͑AFM͒ images and roughness numbers were used to evaluate the post-CMP defect generation under various process conditions and revealed nano/microscratches, pits, voids, and film delamination. For a given material, the removal rate increased with increasing pressure. The dependence of defects on pressure appeared highly driven by the slurry material, pad type, and low-k material properties. Defects increased with increasing pad hardness and decreasing k values. The increasing defects with decreasing k value can be attributed to the lower elastic modulus observed with low-k materials. Removal rates exhibited both a decrease and an increase in conjunction with polish time, depending on the type of low-k material used. AFM analysis showed an improvement in global surface roughness with increasing polish time; however, an increase in localized defects such as pits was also observed. Fourier transform infrared and X-ray photoelectron spectroscopy analyses showed no change in film chemistry under the conditions studied here.With advancements in ultralarge-scale integration, integrated microelectronic device dimensions are continually being scaled down. At present, manufacturers are running 0.11 m technology in their production lines, which increases the number of dies per wafer and reduces manufacturing costs. In addition, higher device speed requirements have forced the industry to include material changes in the device interconnection array. For example, in an attempt to reduce the resistance-capacitance time delay, manufacturers have moved toward a copper damascene process, with copper replacing aluminum and low-k dielectric materials replacing SiO 2 .Chemical mechanical planarization ͑CMP͒ is an important step in the copper damascene process. Copper deposited in the patterned dielectric trenches is planarized by CMP. The primary objective of the Cu-CMP process is to planarize and remove excess copper and the barrier layer. During this process, the underlying dielectric material is exposed. With industry shifts toward ultra low-k materials, very low k values can usually be achieved by using porous/organic materials, which also exhibit low hardness and modulus. However, these relatively weak materials cannot withstand the rigorous CMP process. Additionally, low-k films are less moisture resistant than conventional oxides produced by chemical vapor deposition ͑CVD͒; thus, extended exposure to CMP slurries and the environment affects their properties.Numerous low-k materials are being investigated. The compatibility of these materials with the CMP process is a significant factor in determining the appropriate low-k material to us...

The atomic nitrogen population produced from a microwave electron cyclotron resonance plasma and a microwave plasma has been measured using the nitric oxide gas titration technique for pressures between 0.005 and 0.5 Torr. For 15 W microwave power the atomic nitrogen production efficiency is observed to reach a maximum of 12% at 0.006 Torr. The pressure dependence of atomic nitrogen production efficiency and concentration are found to fall by one order at the pressure where particle mean free path exceeds apparatus dimensions (0.015 Torr). The shift has been attributed to changing electron temperature.

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A transport‐based, three‐dimensional numerical modeling approach has been developed to simulate chemical mechanical polishing processes occurring in microelectronic materials processing. A unique aspect of this model is that the detailed morphology of the slurry flow domain between the wafer and polishing pad is approximated with a regularly updated sequence of geometries evenly positioned along the polishing orbit. Additionally, the modeling approach allows the use of any constitutive relationship for the rheological behavior of the polishing slurry. The local polishing rate is taken to be proportional to the local hydrodyanmic shear stress generated on the to‐be‐polished wafer surface. To illustrate the modeling approach, the development of planarity during polishing of a prototypical 3 × 3 array of square roughness elements was simulated. The rheology of the polishing medium was described as a power‐law fluid with a Newtonian plateau, which is appropriate for an aqueous slurry of colloidal silica. Two modes of pad‐to‐wafer tracking during polishing are discussed. Modeling results show good agreement with typical experimental data. © 2000 The Electrochemical Society. All rights reserved.

The influence of feature-scale surface pattern dimensions on chemical mechanical polishing (CMP) processes has been studied through numerical simulations using a discretized geometry approach. The development of planarity for a symmetrical 3 ϫ 3 array of square roughness elements with various lateral dimensions and spacing was simulated. Geometrical shielding of roughness elements by neighboring elements was found to cause asymmetrical surface polishing during the CMP processes. Given a specified trench spacing, a stronger doming effect was predicted for smaller sized protrusions. For a fixed feature size, the most significant doming effect was found to occur when the trench width is comparable to the gap size between the pad and the protrusion. These effects can be associated with variations in the flow pattern of the polishing slurry in the vicinity of the roughness elements.