| Popis: |
As production CMOS devices shrink to 90nm and below, the requirements for high quality ion beams increase in medium and high current implant systems. Critical variations in device performance can be related to changes in ion beam properties, such as ion beam size, shape and density as well as ion beam angle steering and distribution. Transistor properties are known to be sensitive not just to mean beam angle but also to details of the distribution of angles contained within the beam. As a result, modem single wafer implanters are required to monitor more than just the energy and dose of implanted ions. The process security provided by single wafer ion implantation can be ensured by measurements which verify the angle integrity of each setup and implant. Monitoring of energy contamination, another element of beam quality, allows end users to utilize the improved productivity of decel operation on high current implanters while maintaining minimal and, more importantly, repeatable energy contamination. Finally, real time uniformity monitoring provides assurance that the beam uniformity established during setup is preserved during wafer processing. In this paper, example metrology systems from the VIISta platform will illustrate measurement of these beam quantities. Representative performance data for monitored beam quality and control will be presented. |
