The behavior of metals penetrating the silicon substrate through a screen SiO 2 or Si 3 N 4 film by the collision of arsenic ion and surface metals are quantitatively demonstrated. We have found using silicon step etching followed by ICP-MS and SIMS that 0.1∼8% of surface metals (Fe, Cr, Ni, Cu, and W) penetrate silicon even when implanted through screen SiO 2 film, depending on metal species and the film thickness. The surface metals on a CVD Si 3 N 4 film can also penetrate into the silicon during ion implantation and/or subsequent annealing. W is most difficult to penetrate the thermally-grown SiO 2 film, while W and Cr can easily penetrate a CVD Si 3 N 4 films. We have also found using microwave photoconductive decay measurements that recombination centers are generated in silicon by low level metal penetration even when implanted through screen Metallic contamination on silicon surfaces has a detrimental impact on the performance and yield of ULSI devices. Surface metal impurities degrade the gate oxide integrity while metal impurities dissolved in silicon cause recombination centers and these result in junction leakage, degrade retention characteristics in DRAMs, and cause dark currents in image sensors. Surface metal impurities often penetrate the silicon by thermal diffusion in ULSI processing. The diffusion behavior of these metal impurities in silicon is well-known. [1][2][3] Most metallic contamination occurs during wafer processing, particularly reactive ion etching and ion implantation 4-6 and here it has been reported that metals transported with dopant ion from an ion source or acceleration tube in ion implantation equipment can be deposited on silicon surfaces. 5,6 On the other hand, the behavior of surface metal impurities penetrating by the collision with a dopant ion has not been known. The ion implantation may assist surface metal impurities penetrating the screen films and silicon. The collided metal atoms' penetrating silicon can be prevented by screen films such as SiO 2 or Si 3 N 4 films, 7 in which the diffusion coefficients of metal impurities such as Ni and Cu are smaller than in Si. 8 In this paper, the behavior of metals penetrating the silicon substrate through a thermally grown SiO 2 or CVD Si 3 N 4 film by the collision of dopant ion and surface metals and subsequent annealing are quantitatively demonstrated. The generation of recombination centers due to the metal penetrating silicon is also discussed. ExperimentalCzochralski (CZ) Si (100), (p-type, 8-12 cm), 200 mm diam. wafers were used in this study. A group of wafers was oxidized to form silicon oxides on the surface. The thickness of the silicon oxide was 5 nm, 20 nm, 80 nm, 120 nm, and 160 nm. A Si 3 N 4 film was deposited on the surface of another group of wafers at 700• C by low pressure CVD. The thickness of the Si 3 N 4 film was 20 nm.Next, the silicon wafers were cleaned with NH 4 OH/H 2 O 2 /H 2 O mixture and HCl/H 2 O 2 /H 2 O mixture. The surfaces of the SiO 2 and Si 3 N 4 films of the wafers were hydrophilic. ...

We studied the detection by TXRF of several transition metals on the surface of III-V materials for high mobility channel. It has been found that the lower limits of detection of some transition metals on the surface of III-V materials become higher than that on the Si surface because the sum peaks or Raman scattering peaks as well as the fluorescent X-ray main signals from the materials themselves partially cover those from the transition metals

We have experimentally demonstrated the depth profiles of metals gettered by oxide precipitates in silicon wafers with different densities and sizes of oxide precipitates. It has been found that although the total surface area of the oxide precipitates per unit volume is dispersed uniformly through the wafers or slightly increases with increasing depth below the denuded zone (DZ), more metals are gettered at around the depth where the total surface area of the oxide precipitates sharply increases just below the DZ. It is considered that metals diffused in the DZ are gettered by oxide precipitates near the DZ during cooling, while metals diffused in the deeper regions are dispersedly gettered by each oxide precipitate in deeper regions during cooling.

The electron nonradiative recombination process of photoexcited carriers in as-grown and annealed n=Al0.2Ga0.8As/GaAs heterostructure samples is investigated by using piezoelectric photothermal (PPT) spectroscopy. The PPT signal above the band-gap energy of GaAs substrate decreased when the sample was annealed at 815 °C. In the frequency dependent measurements, the deviations from the 1/f linear function are clearly observed in the AlGaAs/GaAs samples. This critical deviation frequency was found to shift to the lower frequency region by annealing. Our experimental results are explained by assuming that the sample annealing generates an unknown deep level in the AlGaAs epitaxial layer region and this level effectively traps the photoexcited carriers nonradiatively.

We have found that to the detection sensitivity of Total reflection X-ray fluorescent spectrometry (TXRF), the total volume of trace particles generated by vapor phase treatment (VPT) must be increased and metal atoms need to be included in the particles. The detection sensitivity for Cu is enhanced by assisting Cu ionization in the liquid drops condensed form the vapor. We consider that since incident and reflected X-rays resonate 30nm from the surface, the total reflection intensity of metals included in the particles is enhanced.