Basic physical properties as well as electrical and reliability performance of Infusion™ processing were evaluated. This approach, proposed as an alternative to CuSiN and electrolessly deposited Co-alloys, was shown to join the benefits of these two techniques without well-known associated drawbacks. Indeed, it is a uniform process, acting as an efficient Cu diffusion barrier, which does not require specific integration development. Different processes were introduced in a multi-level interconnect stack using ULK/USG stack as IMD, showing excellent electrical properties, and three times electromigration time-to-failure improvement with respect to standard SiCN barrier. However, it was shown that existing process conditions lead to some introduction of N atoms into ULK dielectric, showing there is still some room for process optimization in architectures using un-capped ULKs, to keep the benefits of EM improvement and aggressive effective dielectric constant.

We have characterized two implementations of a new technique called infusion processing for electromigration (EM) lifetime improvement of copper interconnects fabricated on 300 mm wafers using 65-nm node design rules and porous SiOC ILD (CVD, k=2.5). In the first implementation, silicon and nitrogen were infused into the surface of copper wires before dielectric barrier deposition. In the second implementation, the process time of this same infusion process was increased resulting in silicon nitride (SiN) film deposition. In this case, the SiN film served as the dielectric barrier, replacing the traditional CVD-deposited dielectric barrier film. The EM lifetime for both types of samples increased by roughly an order of magnitude compared to the process of record, which employed a SiCN dielectric barrier. The infusion process had no effect on stress-induced voiding (SIV) or time-dependent dielectric breakdown (TDDB). The infusion process's effect on copper resistivity, line-to-line capacitance and leakage, and via resistance are discussed.

Gas cluster ion beams are evaluated as a sealing technique for a porous low-k dielectric (LKD-5530). It is shown that sealing can be obtained with this technique at high beam energies and high doses, but that the depth of low-k damage is larger than can be allowed for future integration nodes. More interestingly, the induced surface modification can be instrumental in reducing the required barrier layer thickness. A surface smoothening of the porous surface by a low energy bombardment enables sealing by a thinner Ta diffusion barrier layer.

We report for the first time results on infusion doping of boron for ultra shallow junctions (USJ). Using B/sub 2/H/sub 6/ or BF/sub 3/ source gas, the resulting USJ boron dopant profile measured by SIMS shows no evidence of channeling with extreme abruptness of <2.5nm/decade for a 12 nm shallow junction. Infusion doping shows a power log to the 1/3 relationship between energy to junction depth in contrast to the traditional linear fit observed with ion implantation due to nuclear stopping power effects. Boron surface doping levels of 1-2E22/cm/sup 3/ for 2E16/cm/sup 2/ doses were achieved. Dopant activation using low temperature furnace annealing from 450/spl deg/C to 950/spl deg/C were compared using standard 4PP and non-penetrating elastic material 4PP for sheet resistance measurements,on these USJ structures. Also, electrically active dopant profiling was conducted using spreading resistance profile (SRP) for USJ junction depth (Xj) comparison to SIMS. Use of amorphizing implantation resulted in lower Rs values after low temperature SPE annealing.

Gas-cluster ion-beam (GCIB) processing of surfaces provides individual atoms within an accelerated gas cluster (∼1,500 atoms per cluster), an energy approximately equal to the individual bond energy of the target surface atoms. The gas-cluster beam is thus capable of providing smoothing and etching of the extreme surface of numerous semiconductors, metals, insulators, and magnetic materials. For semiconductor material systems, the gas-cluster processing effect on the surface and subsurface material is of critical interest for device and circuitry application integrity. In the case of III–V GaSb, chemo-mechanical or touch polishing is the final step in the semiconductor-wafer manufacturing process, often leaving scratches of various depths or damage on the polished surface. In this paper, we report the GCIB etching and smoothing of chemical-mechanical polished GaSb(100) wafers. Using a dual-energy, dual gas-cluster source process, ∼100 nm of material was removed from a GaSb(100) surface. Atomic-force microscopy (AFM) imaging and power spectral-density (PSD) analysis shows significant decrease in the post-GCIB root-mean-square (Rms) roughness and peak-to-valley measurements for the material systems. X-ray rocking-curve analysis has shown a 24-arcsec reduction in the full-width at half-maximum (FWHM) of the (111) x-ray diffraction peak of GaSb. High-resolution transmission-electron microscopy (HRTEM) shows the crystallinity of the subsurface of the pre- and post-GCIB surfaces to be consistent, following the 1 × 1016 ions/cm2 total-fluence processes, with dislocation density for both pre- and post-GCIB cases below the HRTEM resolution limit. X-ray photoelectron spectroscopy (XPS) indicates a strong Ga 3p electron binding-energy intensity for gallium-oxide formation on the GaSb surface with the use of an oxygen GCIB process. Analysis of the Ga 3p electron binding-energy peaks in the XPS data in conjunction with HRTEM indicates a higher Ga or GaSb content in the near-surface layer (less stoichiometric-oxide presence) with use of a CF4/O2 GCIB process. The same peak analysis indicates that the surface gallium-oxide state is nearly unchanged, except in thickness, with the use of an O2-GCIB second step. The material results suggest that GCIB provides a viable method of chemo-mechanical polish (CMP) damage removal on group III–V material for further device processing.

This paper investigates the use of gas cluster ion beam (GCIB) processing on SOI substrates for reducing the high frequency surface roughness of the starting material while improving the wafer uniformity. AFM images and power spectral density measurements of the pre- and post-GCIB surfaces are examined to determine the spatial-frequency range of the surface features most affected by the gas clusters.

Integration of porous low-k materials for interconnect technology at the 45nm node presents many challenges to etch, ash and cleans processes. Dry processing with a gas cluster ion beam (GCIB) employs a highly energetic beam of loosely bound atomic or molecular clusters. We will show the ability of GCIB to pore seal, etch and ash p-MSQ features, while minimizing low-k film damage as compared to traditional plasma processes.