Use%20of%20Data%20Analysis%20and%20TCAD%20Simulations%20to%20Understand%20the%20Characteristics%20and%20Reliability%20of%20High%20Voltage%20MOS%20Transistors - PowerPoint PPT Presentation
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Use%20of%20Data%20Analysis%20and%20TCAD%20Simulations%20to%20Understand%20the%20Characteristics%20and%20Reliability%20of%20High%20Voltage%20MOS%20Transistors
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Title: Author: JC Last modified by: Mani Created Date: 3/9/2001 3:00:19 AM Document presentation format: On-screen Show (4:3) Other titles – PowerPoint PPT presentation
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Title: Use%20of%20Data%20Analysis%20and%20TCAD%20Simulations%20to%20Understand%20the%20Characteristics%20and%20Reliability%20of%20High%20Voltage%20MOS%20Transistors
1
Use of Data Analysis and TCAD Simulations to
Understand the Characteristics and Reliability of
High Voltage MOS Transistors
- Jone F. Chen
- Department of Electrical Engineering and
Institute of Microelectronics,
National Cheng Kung University, Tainan, Taiwan
2
Purpose
- High voltage metal-oxide-semiconductor (MOS)
transistors are widely used in smart power
management integrated circuits (IC),
liquid-crystal display (LCD) drivers, and NAND
flash memory periphery circuitry because of the
compatibility to be integrated into standard
complementary metal-oxide-semiconductor (CMOS)
process. - Since high voltage MOS transistors are operated
under high voltage, breakdown voltage (VBD) is a
critical device parameter and hot-carrier induced
device degradation is an important reliability
concern. - This work reports analysis of VBD and hot-carrier
induced device degradation in high voltage MOS
transistors with varied process in drift region.
3
Outline
- Off-state Breakdown
- Hot-carrier Induced Degradation
- TCAD Simulations
- Device Description
- Results and Discussions
- Conclusions
4
Off-state Breakdown
- High E-field in the junction causes electron/hole
pair generation. This avalanche multiplication
results in breakdown.
5
Hot-carrier Induced Degradation
- Carriers accelerate in high E-field region and
gain sufficient energy to create damage in gate
oxide or oxide/Si interface, degrading device
characteristics.
6
Hot-carrier Stress Procedure
- Stressing were carried out at high drain voltage
and interrupted periodically to measure ID
degradation.
7
Technology Computer-Aided Design (TCAD)
Simulations
About TCAD
- TCAD combines two kinds of tools
- Core tools in charge of running different parts
of simulations. - Interactive tools are which users manage their
settings.
Runtime Output
ATHENA
Structure File
ATLAS Device Simulator
Log Files
TonyPlot Visualization Tool
DeckBuild
Command File
Solution Files
8
Device Description
- High voltage MOS transistors were fabricated by
an advanced CMOS compatible process. The length
of gate and N- drift region are 2 mm and 1.2 mm,
respectively. - Four devices (A, B, C, D) were fabricated. A is
the control device. B, C, D are implanted with
BF2 with low, medium, and high doping levels in
N- drift region.
9
Net Doping
- Device D has less net doping due to BF2 implant
in drift region.
A
D
10
VBD Results
- Device D has the highest VBD. Higher BF2 implant
dosage results in higher VBD .
11
VBD Analysis
- TCAD simulations suggest that higher VBD in
device D is due to the absence of high E-field in
drift region.
A
D
12
Hot-carrier Stress Results
- Device D has the greatest ID degradation. Higher
BF2 implant dosage results in higher ID
degradation.
13
Hot-carrier Stress Analysis
- TCAD simulations show that the current-flow path
in device D is closer to Si-SiO2 interface. The
effect of hot-carrier induced damage on ID
degradation is greater, leading to enhanced ID
degradation in device D.
A
D
14
Conclusions
- BF2 implant in drift region of high voltage MOS
transistors results in higher VBD. - BF2 implant in drift region of high voltage MOS
transistors enhances hot-carrier induced device
degradation. - Care should be taken in determining drift region
process because a trade-off between VBD and
hot-carrier induced device degradation is
observed.
15
Thank you for your Attention
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