The reduction of alpha particle emission induced soft error upset has been identified in the industry association's National Technology Roadmap for Semiconductors as a major concern. However, the measurement of ultratrace alpha radiation levels is difficult, and has become a source of conflict between materials suppliers and microchip manufacturers. Development of an inexpensive standardized test method has been solicited to allow for accurate analysis to a detection limit far below the current low-alpha standards. Not only will this alleviate the misunderstandings between suppliers and users, but also will permit further research into the source and removal of the ultratrace contamination. The process to be developed under this proposal utilizes three unique principles in order to provide an improvement in detection limit of more than a factor of 50 over the best available technology. First, this process evaluates volumetric content of alpha activity rather than surface content, greatly increasing the effective size of the sample. Second, it requires no chemical separations or processes to isolate trace alpha emitters from the encapsulant material. Third, it utilizes a unique, digital counting system that provides precise selectivity for alpha decay events, thus eliminating background radiation and improving alpha detection sensitivity. COMMERCIAL APPLICATIONS: The method for ultratrace detection of alpha emissions developed under this proposal will be of value not only to the semiconductor industry but also for environmental monitoring at various governmental sites formerly used for nuclear weapons research or uranium production. The proposed device will be economical enough to allow surveying of contamination fields to map plume development.
