Taiwan Semiconductor Manufacturing Company has announced that it had successfully managed to achieve “functional” 64Mb SRAM yield across all of its three 28nm manufacturing processes.
Achieving 64Mb SRAM yield across all three 28nm process nodes is striking. It is particularly noteworthy because this achievement demonstrates the manufacturing benefits of the gate-last approach that we developed for the two TSMC 28nm high-k metal gate processes,” explained Dr. Jack Sun, vice president, Research and Development at TSMC.
Each bit in an SRAM is stored on four transistors, hence, a 64Mb SRAM chip consists of about 256 million transistors. Not only 256 million transistors not a large chip nowadays, but “functional” yields of a chip featuring only very similar structures does not point to viable yields for logic chips.
Earlier this year TSMC faced harsh criticism for low yields of chips produced using 40nm fabrication process. In an early stage of production yields only achieved 30%, later on the company managed to improve it to 60%.