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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