A SOI material with thick BOX (2.2 μm) was successfully fabricated using the Smart-cut technology. The thick BOX SOI microstructures were investigated by high resolution cross-sectional transmission electron microscopy (XTEM), while the electrical properties were studied by the spreading resistance profile (SRP). Experimental results demonstrate that both structural and electrical properties of the SOI structure are very good.
WU Yan-Jun, ZHANG Miao, AN Zheng-Hua, LIN Cheng-Lu(State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology,the Chinese Academy of Sciences, Shanghai 200050)
Al precipitates as well as cavities (or open-volume detects) are known for their ability to getter impuri-ties within Si. In order to compare their relative gettering strength we produced both Al precipitates and cavities atdifferent depths within one Si wafer. This was done by H+ and Al+ implantation with different energies and subse-quent annealing process, resulting in Al-Si alloy and cavities at depth of 300 nm and 800 nm, respectively. Cu wasthen implanted with an energy of 70 keV to a fluence of 1 × 1014 / cm2. The Cu implanted samples were annealed attemperature from 700℃ to 1200℃. It was found that Cu impurities were gettered primarily by the precipitated Allayer rather than by cavities at the temperature of 700～1000℃, while gettering of Cu occured in both regions at thetemperature of 1200℃. The secondary ion mass spectrometry and transmission electron microscopy analyses wereused to reveal the interaction between Cu impurities and defects at different trap sites.
WU Yan-Jun, ZHANG Miao, ZHANG Ning-Lin, LIN Cheng-Lu(State Key Laboratory of Functional Materials for Informatics. Shanghai Institute of Microsystem and Information Technology.the Chinese Academy of Sciences, Shanghai 200050)
In this paper, the gettering of Cu impurities in silicon-on-insulator (SOI)materials is studied. Nanovoids are formed in the substrate of SOI beneath the buried oxide (BOX) byroom temperature H^+ (3.5 x 10^(16) / cm^2) or He^+ (9 x 10^(16) / cm^2) implantation andsubsequent annealing at 700℃. The gettering of different doses of Cu (5 x10^(13)/cm^2, 5x10^(14)/cm^2, 5 x 10^(15)/cm^2), which are introduced in the top Si layer by ion implantation, to thenanovoids are investigated by cross-section transmission electron microscopy (XTEM) and secondaryion mass spectroscopy (SIMS). The results demonstrate that Cu impurities in the top Si layer candiffuse through the buried oxide (BOX) layer of SIMOX and Smart-Cut SOI at temperature above 700℃and be trapped by the nanovoids. Some of Cu impurities can be captured by the intrinsic defects atthe BOX interface of SIMOX, but will be released out at high temperatures. The gettering effect ofSIMOX intrinsic defects at BOX is much rower than that of the nanovoids. No Cu impurities aretrapped at the perfect BOX interfaces of Smart-Cut SOI. After 1000℃ annealing, high dose of Cu (3.6x 10^(15)/cm^2) was gettered by the nanovoids. The Cu gettering efficiency to the nanovoidsincreased with the decreasing of Cu doses. When the Cu doses in the top Si layer were lower than 4 x10^(15) /cm^2, nanovoids could getter more than 90% of the Cu impurities and reduce the Cuconcentration in the top Si layer to less than 4%. The results indicate that nanovoids gettering isa promising method for removing the impurities in SOI materials.
