国立清华大学材料科学工程学系

improved retention and endurance
Electroceramic thin films Lab. 427R NTHU. MSE
1. Introduction - Nanocrystal Memory
10-16 nm
Source
Gate
Gate oxide
3-4 nm Nanocrystal s
(1) Hot-electron injection
(2) F -N tunneling
8-15 nm
10-20 nm 5-7 nm
Drain
For the case of floating gate devices, a single defect can discharge the stored memory charge of the devices due to the conductive properties of the floating polysilicon gate
Tunnel oxide
5-8 nm 2-4 nm
90 nm
drain
Aligned discrete nanocrystals as floating gate
The nanocrystal memory
Professor Tai-Bor Wu Department of Materials Science and Engineering,
National Tsing Hua University 吳泰伯 教授
國立清華大學材料科學工程學系
Electroceramic thin films Lab. 427R NTHU. MSE
Electroceramic thin films Lab. 427R NTHU. MSE
1. Introduction – SONOS Memory
Source
Gate SiO2 4 nm Si3N4 5 nm
SiO2 2 nm
Drain
SONOS is a multi-dielectric device consisting of an oxidenitride-oxide (ONO) sandwich.
Flash memory
Application : mobile phone, digital camera, MP3, PDA, …etc.
Conventional memory
Floating Gate Memory
Emerging Memory
Shortcoming : (1) high programming voltage (2) lower writing speed (3) poor retention and endurance
+ OFF (accumulation)
Darin Current
Gate Voltage, VGS
Basic Operation Principle
Storage of charges
Gate
Source --------
n+ P -sub
QT Drain
n+
Darin Current
Erased
Both positive and negative charges can be stored in discrete deep traps in the silicon nitride (SiN) layer.
Because for SONOS, a single defect will not cause the discharge as the stored charge lies in isolated sites within the silicon nitride dielectric.
Outline
1. nonvolatile memory introduction 2. Pt nanocrystal self-assembled fabrication 3. characterization of Pt nanocrystal memory 4. Summary
Electroceramic thin films Lab. 427R NTHU. MSE
A non-volatile memory does
not lose its information
contents when the power is
turned off.
Flash Memory, FeRAM, MRAM, CRAM (Chalcogenide Random Access Memory), Single Electron Memory
DRAM, SRAM
A volatile memory loses its
information contents when
the power source is removed.
Electroceramic thin films Lab. 427R NTHU. MSE
1. Introduction – Flash Non-volatile Memory
NanocryHale Waihona Puke Baidutal Memory
SONOS Memory
Electroceramic thin films Lab. 427R NTHU. MSE
MOSFET characteristics
+
gate
n+
n+
P type Si
gate n+ +++++ n+
P type Si
ON (depletion)
1. Introduction – Semiconductor Memory
Semiconductor memory
Solid-state memories are also
called semiconductor
memories.
Non-Volatile Memory (NVM)
Volatile Memory
Programmed
Sense voltage
Gate Voltage, VGS
1. Introduction – Floating Gate Memory
23-42 nm
Source
Control gate ONO
Floating gate Oxide
90 nm
Charge transfer :