Toshiko Koizumi

Title: Toshiko Koizumi: Innovator in Semiconductor Memory Technology

Introduction

Toshiko Koizumi is a prominent inventor based in Kokubunji, Japan. She has made significant contributions to the field of semiconductor memory technology, holding 2 patents that showcase her innovative spirit and technical expertise.

Latest Patents

Her latest patents include a non-volatile semiconductor memory device erasing operation. This invention relates to a tunnel erasing device for a non-volatile semiconductor memory device, which comprises a source region and a drain region. It features a floating gate electrode that is superposed on at least one of these regions through a gate insulating layer. Additionally, a control gate electrode is disposed over the floating gate electrode through an interlayer insulating layer. This invention is characterized by a preliminary erasing operation where a voltage is applied to at least one of the source or drain regions, with the control gate electrode grounded. This voltage is relatively lower than a predetermined voltage, which is applied prior to the predetermined voltage.

Another notable patent is for a semiconductor memory device, specifically an EEPROM. In this device, a memory cell is constituted by a floating gate electrode and a control gate electrode. It includes a first semiconductor region provided in a main surface portion of the semiconductor substrate on one end side of the gate electrodes, which is connected to the data line. A second semiconductor region is provided in a different main surface portion of the semiconductor substrate on the opposing end side of the gate electrodes, which is connected to the grounding line. The drain is utilized differently depending on the operations for writing, reading, and erasing data. The impurity concentration in the first semiconductor region is selected to be lower than that of the second semiconductor region, enhancing writing and erasing characteristics while increasing reading speed.

Career Highlights

Throughout her career, Toshiko Koizumi has worked with notable companies such as Hitachi, Ltd. and Hitachi Device Engineering Co., Ltd. Her experience in these organizations has allowed her to develop and refine her expertise in semiconductor technology.

Collaborations

Toshiko has collaborated with esteemed colleagues, including Hitoshi Kume and Tetsuo Adachi. Their joint efforts have contributed to advancements in the field of semiconductor memory devices.

Conclusion

Toshiko Koizumi's innovative work in semiconductor memory technology has made a lasting impact on the