We have utilized plasma immersion ion implantation (Pill) to demonstrate effective gettering of metallic impurities in silicon wafers. Metallic impurities such as Ni, Cu or Au were intentionally diffused into Si as marker impurities. The Ar or Ne atoms were ion- ized in an electron cyclotron resonance (ECR) plasma chamber. The ions were accelerated by a negative voltage applied to the wafer and implanted into the wafer. The as-implanted saturation dose can be as high as 5x10 to the 16th cm-2. After an annealing step at 1000 degrees centigrade for 1 hour in a N2 ambient, the retained doses and the amount of gettered impurities were measured with Rutherford backscattering spectrometry (RBS). With a retained Ar dose in 10 to the 15th cm-2 range after annealing, the gettered Ni, Cu and Au were 3.0x10 to the 14th cm-2, 3.0x10 to the 14th cm-2 and 4.4x10 to the 13th cm-2 respectively. and
We have demonstrated gettering of metallic impurities in silicon wafers with plasma immersion ion implantation (PIII). Ar or Ne gas was ionized in an electron cyclotron resonance (ECR) plasma chamber. The positive charged ions were accelerated by a negative voltage applied to the wafer and implanted into the wafer. Metallic impurities were intentionally introduced into Si through thermal diffusion as marker impurities before implantation. The as-implanted dose was around 1x10 to the 16th cm-2. After an annealing step at 1000 degrees centigrade for 1 hour in a N2 ambient, the retained doses and the amount of gettered impurities were measured with Rutherford backscattering spectrometry (RBS). With a retained Ar dose in the 3.0x10 to the 14th cm-2, 3.0x10 to the 14th cm-2 and 4.4x10 to the 13th cm-2 respectively. A discrepancy between implanted Ar dose and estimated Ar dose from charge integration was found and a model is proposed to explain this discrepancy. The Ar loss mechanism during gettering annealing has also been investigated.