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Shigeki OHBAYASHI Tomohisa WADA Toshihiko HIROSE Kenji ANAMI
This letter describes the fan-out optimization method of the SRAM decoder having line capacitance that minimizes the total delay time. It is shown that the total delay time of the SRAM decoder optimized by this mothod is less than that of the equal fan-out condition.
Masako FUJII Koji NII Hiroshi MAKINO Shigeki OHBAYASHI Motoshige IGARASHI Takeshi KAWAMURA Miho YOKOTA Nobuhiro TSUDA Tomoaki YOSHIZAWA Toshikazu TSUTSUI Naohiko TAKESHITA Naofumi MURATA Tomohiro TANAKA Takanari FUJIWARA Kyoko ASAHINA Masakazu OKADA Kazuo TOMITA Masahiko TAKEUCHI Shigehisa YAMAMOTO Hiromitsu SUGIMOTO Hirofumi SHINOHARA
We propose a new large-scale logic test element group (TEG), called a flip-flop RAM (FF-RAM), to improve the total process quality before and during initial mass production. It is designed to be as convenient as an SRAM for measurement and to imitate a logic LSI. We implemented a 10 Mgates FF-RAM using our 65-nm CMOS process. The FF-RAM enables us to make fail-bit maps (FBM) of logic cells because of its cell array structure as an SRAM. An FF-RAM has an additional structure to detect the open and short failure of upper metal layers. The test results show that it can detect failure locations and layers effortlessly using FBMs. We measured and analyzed it for both the cell arrays and the upper metal layers. Their results provided many important clues to improve our processes. We also measured the neutron-induced soft error rate (SER) of FF-RAM, which is becoming a serious problem as transistors become smaller. We compared the results of the neutron-induced soft error rate to those of previous generations: 180 nm, 130 nm, and 90 nm. Because of this TEG, we can considerably shorten the development period for advanced CMOS technology.
Hirotoshi SATO Shigeki OHBAYASHI Yasuyuki OKAMOTO Setsu KONDOH Tomohisa WADA Ryuuichi MATSUO Michihiro YAMADA Akihiko YASUOKA
This paper reports a 32k32 1-Mbit CMOS synchronous pipelined burst SRMA. A clock access time of 3.6 ns and a minimum cycle time of 9 ns(111 MHz operation) were obtained. An active current of 210 mA at 111 MHz and a standby current of 2 µA were successfully realized. These results can be obtained by a new activation control method in which the internal clock pulses control the decoders, the low resistive bit line and memory cell GND line and the optimization of write recovery timing and data sense timing.