As Semiconductor Devices Shrink so do their Reliability and - - PowerPoint PPT Presentation

As Semiconductor Devices Shrink so do their Reliability and Lifetimes

National Software and Airborne Electronic Hardware Standardization Conference August 20-21 Denver, CO

Lloyd Condra, Boeing Gary Horan, FAA Bill Scofield, Boeing

Outline

• Background

As semiconductor devices shrink, so do their reliability and lifetimes

• What we have done about it

AVSI research results

• What we have yet to do

Tool development

• Implementation

What Does “COTS” Mean?

32 Flavors of COTS

(Baskin Robbins only has 31)

Standard Modified System Equipment Part Sub-assembly (module) Mil-Aero Industrial Commercial Consumer

Our Challenge

We develop processes, methods, and standards that allow our customers to………. …….Design, produce, certify, and support products using parts and materials from Complex Adaptive Systems. Our COTS supply chain is a Complex Adaptive System that evolves according to forces beyond our control

The COTS Semiconductor Industry is a Complex Adaptive System

500 400 300 200 100 1994 1996 1998 2000 2002 2004 2006 2008 Voltage Scaling Cu Conductors Low-Dk Dielectrics Model-based Design

Feature size, nm Driving factors:

• Cost
• Speed
• Size
• Time-to-market

‘Incidental’ factors:

• Reliability
• Configuration continuity
• What aerospace needs

A feature is a line width, gate length, etc. of a CMOS gate.

Semiconductor Wearout

1995 2005 2015 Year produced 0.1 1.0 10 100 1000 Mean Service life, yrs. Computer/cell phone lifetimes Mil/Aero lifetimes 0.5 mm 0.25 mm 130 nm 65 nm 35 nm Technology Service Life (years) 1.0μ 0.1μ 0.35μ 0.18μ 1990 1995 2000 2005 10 100 Typical service life goal (10 yrs.) Margin

Source: E. Snyder (Sandia), IRPS, 2002)

Most microcircuits are designed for 3-10 year service life Strong motivation to limit insight into long- term reliability

Predictions Confirmed by Experience*

*Source: DfR Solutions

Wearout failures (Hot Carrier Injection) in 90nm ASIC devices

• Telecom OEM: 10% failure within 4 years
• Process Monitoring OEM: 20% failure within 3 years

Major manufacturer of graphic processor units (GPU) limits maximum junction temperature to 80ºC in order to meet 5-year lifetime requirement

Predictions Confirmed by Testing

AVSI #17 Results

Avionics In- service Data 0.25 μm: ~20-50 FIT 90 nm: ~ 100 - 300 FIT 700 FIT

Current state-of-the-art is 45 nm Test system at Tower semiconductor

What We Have Done About Early Semiconductor Wearout

• Aerospace Vehicle Systems Institute Project #17

– Participants: Boeing, Honeywell, Goodrich, GE, Rockwell Collins, DoD, FAA, NASA – Time span: 2003-2007 – Subcontractor: Dr. Joseph Bernstein, U of MD

• Results

– Literature search failure mechanisms, models, parameters – Confirmed models by testing – “Alpha” version of FaRBS software – Avionics system design handbook

1.E+01 1.E+02 1.E+03 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 Time (equivalent hours) FIT

Predictions Confirmed by Testing

AVSI #17 Results

Acceptable for Commercial Applications Required for Avionics 2000 2005 2010

Early Wearout Confirmed!!!

Wearout Mechanisms

Electromigration Gate

• xide

Gate Source Drain Conducting channel Gate

• xide

Gate Drain Source Conducting channel N-substrate Trench isolation P+ P+ P-well N+ N+ Oxide breakdown Hot carrier injection (HCI) Negative bias temperature instability (NBTI)

Voltage stresses Current stresses

e x p ( )

T D D B

a T D D B g

k T

E V

γ

−

⋅

exp( ) exp( )

a N B T I g N B T I

kT

E V γ

− ⋅

exp( ) exp ( )

H C D aH C D d

kT

E V γ

⋅

exp( )

n a E M

kT

E J

− ⋅

TDDB NBTI HCI EM

FaRBS Reliability Software

BQR Reliability User Supplied

90 nm NBTI Degradation

Reliability Prediction with FaRBS

β=1 ~3 yrs. ~0.98 ~2% failure in 2-4 years 0.85 1.00 0.90 0.95 20 5 10 15 Reliability vs Time Time, (yr) Reliability, R(t)=1-F(t) Fast Slow Typ

Example FaRBS Outputs

Reliability and Failure Rate Estimates

36Mb SRAM

0.988 0.99 0.992 0.994 0.996 0.998 1 2 4 6 8 10 12 14 16 18 20 Time (years) Reliability

36 MB SRAM 90 nm technology 1.2 volts, 70ºC

Board failure rate

100 200 300 400 500 600 700 800 900 2 4 6 8 10 12 14 16 18 20 Time (years) FIT

36 MB SRAM 1GB DRAM

Example FaRBS Output

Board failure rate

100 200 300 400 500 600 700 800 900 2 4 6 8 10 12 14 16 18 20 Time (years) FIT

Board with one 36Mb SRAM and one 1GB DRAM

1 FIT = 1 failure/109 hrs.

Effect of Feature Size

Source: Wu, E.Y., and R.-P. Vollertson, “On the Weibull Shape Factor of Intrinsic Breakdown of Dielectric Films and Its Accurate Experimental Determination – Part I: Theory, Methodology, Experimental Techniques,” IEEE Transactions on Electronic Devices, vol. 49, no. 12, December

• 2002. Pp. 2131-2140.

β = 1.3 β = 1.6 β = 2.1 β = 4.0 β = 7.3

Effect of Voltage on TDDB

Time-to-fail (s)

100 101 102 103 104

l ( l (1 F))

• 4
• 3
• 2
• 1

1 7.75V 7.50V 7.25V 7.00V BetaW=1.32

• 256M DRAM, 78nm CMOS process
• Gate oxide thickness approximately 5.5nm
• Operating voltage 1.5V.
• HTOL at 5.0V/125C
• Exponential voltage acceleration with γ = 2.7

What We Have Yet To Do

AVSI Project #71

– “Commercial” version of FaRBS software (DfR Solutions) – Verify software by test data – “Beta test” FaRBS software tool on selected Boeing systems – Update with future technology data, models, and parameters

Invite participation by others Provide inputs to aerospace design and reliability documents

– DO-254 – MIL-HDBK-217

“Commercial” FaRBS Inputs

Make AVSI 17 results “user-friendly”

–Graphical user interface (GUI) designed to interact with a wide range of users, e.g., design engineers, reliability engineers, etc. –Requires a minimal set of inputs

• Manufacturer
• Manufacturer part number
• Duty cycle
• Use environment (temperature)

–Assumptions can be modified by expert users

• Operation at rated voltage
• Only mfr.-specified thermal solutions (no uprating)
• International Technology Roadmap for Semiconductors (ITRS)

models and parameters

• Applicable to <130nm technology
• Default and package failure rates from handbooks (-217,

Telcordia) or part manufacturer

“Commercial” FaRBS Outputs

Make AVSI 17 results “user-friendly”

• Failure rate as a function of time
• Results can be exported in a .doc or .xls / .csv format
• Expert user will be able to extract failure rates for each

failure mechanism

• Validation link will

provide details on approach and experimental results

Implementation

Update System Reliability and Certification Documents

Hardware Reliability Prediction MIL-HDBK-217 Hardware Design Assurance RTCA DO-254 Software Design Assurance RTCA DO-178B System Certification Analysis System FMEA System FTA System Functional Hazard Assessment Updates needed