Impact of copper contamination on the quality of silicon oxides

Abstract

To study the impact of metal contamination on the quality of gate oxides, (100) silicon wafers were intentionally contaminated with copper from the backside. The in-diffusion of copper and/or oxidation were performed in a rapid thermal annealing system. Gate oxide areas with low breakdown fields of about 2-3 MV Icm were located in a pinhole detector and correlate very well with the contaminated areas revealed by Secco defect etching. Using various analytical tools the failure mechanism was found to be related to the formation of eu-rich precipitates at the Si0 2 /Si interface. Depending on the in-diffusion temperature (and hence on the supersaturation of Cu in Si), two different mechanisms were observed: At high supersaturation (1200 °C/30 s) Cu-rich silicide particles can bend, crack, and finally penetrate the oxide layer. At lower in-diffusion temperatures (900 °C/60 s) lens-shaped Cu silicides form at the Si0 2 /Si interface and reduce the oxide thickness,

(Ba,Sr)TiO3 Thin Films for Dram’s

“…Degradation in gate oxide integrity is a common problem [131][132][133][134]. This degradation occurs not only when contamination is present prior to growth of the Si02 but also when the contaminant can diffuse into the already formed oxide [131].…”

Potassium sorbate as an inhibitor in copper chemical mechanical planarization slurries. Part II: Effects of sorbate on chemical mechanical planarization performance

“…One of the drawbacks of using copper in integrated circuits is its tendency to diffuse through the interlayer dielectrics into the silicon [6]. In order to avoid diffusion, a thin barrier layer (such as Ta, TaN or TiN) is deposited [7,8].…”

Enhanced gettering of iron impurities in bulk silicon by using external direct current electric field

“…The high diffusivity and solubility of these metal impurities in silicon allow fast diffusion of these impurities into the bulk silicon wafer until achieving supersaturation. 1,2 The subsequent precipitation of these heavy metals during silicon device fabrication processes, which involve thermal annealing cycles, can degrade the dielectric properties of gate oxides 3,4 and p-n junctions, 5,6 resulting in severe leakage current and early electrical breakdown.…”