Examination of the effects of aluminum contamination for PSII fabricated diodes

Abstract

Summary form only given. Plasma Source Ion Implantation (PSII) has long been regarded as a possible alternative to classical ion implantation. The benefits of PSII, such as low energy high dose implants and its comparatively small footprint, become increasingly tempting for integrated circuit fabrication as device dimensions shrink. An open question concerns the effect of plasma-sputtered contaminant ions on device characteristics. To address the contamination issue, a suite of experiments is currently underway which will quantify the allowable level of contamination in a diode array. The array of diodes is fabricated on 3 inch N type P-doped silicon wafers. The processing of the wafers is standard except for the implantation step. The implantation step occurs just after the oxide etch, and includes both the implantation of the boron ions as well as the contaminant ions. In every case the energies of both ions will be the same to simulate the conditions found within the PSII chamber. The implantation process will utilize controlled ion beam implants to introduce measured quantities of both the boron and contaminant ions. As a result, control of the absolute, as well as the relative dose of the impurities can be achieved. The first contaminant to be studied is aluminum since it represents a preferred material for constructing PSII chambers, and it is expected that aluminum will be sputtered from the chamber walls. The experiment is a 2/sup 3/ factorial design varying implant energy, aluminum concentration and and their effects on the performance of test diodes of various dimensions. The measured responses are ideality factor, breakdown voltage and reverse bias leakage current.