Polysilicon Channel TFT With Separated Double-Gate for Unified RAM (URAM)—Unified Function for Nonvolatile SONOS Flash and High-Speed Capacitorless 1T-DRAM

Author

Han, Jin-Woo ; Ryu, Seong-Wan ; Kim, Dong-Hyun ; Choi, Yang-Kyu

Author_Institution

Sch. of Electr. Eng. & Comput. Sci., Korea Adv. Inst. of Sci. & Technol., Daejeon, South Korea

Volume

57

Issue

3

fYear

2010

fDate

3/1/2010 12:00:00 AM

Firstpage

601

Lastpage

607

Abstract

Unified random access memory (URAM) with a separated double-gate is demonstrated on a fully depleted polysilicon (poly-Si) thin-film-transistor (TFT) template. Integration of a front-gate dielectric of tunneling oxide/nitride/control oxide (O/N/O) and a floating poly-Si channel provides the two versatile functions of nonvolatile silicon oxide-nitride oxide-semiconductor Flash memory and high-speed capacitorless single-transistor 1T-DRAM in a single transistor. In this design, the memory mode of URAM is selected according to user specifications. As the back-channel is assigned for capacitorless 1T-DRAM while the front-channel is devoted for Flash memory, spatial separation minimizes undesired soft programming in the front O/N/O layer and allows for capacitorless 1T-DRAM operation irrespective of the data state of the nonvolatile memory. This feature presents interference-free operation between the two modes. In addition, the virtue of the TFT process allows the potential for stackable memory for ultra-high-density era.

Keywords

DRAM chips; field effect memory circuits; flash memories; thin film transistors; IT-DRAM; TFT; URAM; fully depleted polysilicon thin-film-transistor; high-speed capacitorless single-transistor IT-DRAM; nonvolatile SONOS flash; nonvolatile silicon oxide-nitride oxide-semiconductor flash memory; unified RAM; unified random access memory; Dielectrics; Flash memory; Interference; Nonvolatile memory; Random access memory; Read-write memory; SONOS devices; Silicon; Thin film transistors; Tunneling; Capacitorless 1T-DRAM; Flash memory; nonvolatile memory (NVM); separated double-gate; silicon oxide–nitride oxide–semiconductor (SONOS); thin-film transistor (TFT); unified random access memory (URAM);

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/TED.2009.2038584

Filename

5404421