An isolation technology for high performance bipolar memories - IOP-II

An isolation technology for high performance bipolar memories has been developed. This process is called IOP-II (Isolation with Oxide and Poly-silicon), which uses steep silicon U-groove for isolation instead of conventional IOP´s V-groove. In order to investigate the applicability of this technology, a conventional 1 K-bit ECL RAM is scaled down at ratios of 0.8, 0.7 and 0.6 using IOP-II. They show good isolation characteristics and improved access times of 5.8ns, 4.8ns and 4.4ns, respectively, while that of conventional one is 7.4ns. IOP-II has made it possible to develop a high speed and density 16 K-bit RAM with 15ns access time. A 3-µm wide and 5-µm deep isolation is used. One bit memory cell size is 750µm and minimum emitter size 1.5×3µm².