Reduction of Soft Error Rates in Memory and Logic Circuits by Material Purification of Selective Ionization of Contaminants
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
The problem of alpha-particle-induced soft error rate (SER) in both memory and logic circuits is well known. The original concern regarding SER was in connection with package radioactivity, but this was dealt with by coating the chips. Unfortunately, even after this shielding there remains a significant residual SER. The reason is that various metals on the chips themselves are radioactively contaminated, chiefly by Th and U. Clearly, shielding can not help against this source. Therefore, the purification of the metals on the chip is highly desirable. The problem is that the radioactive contaminations that we are dealing with are in the part per billion concentration range, and no known chemical method is successful in reducing these contaminant levels.