集成電路ESD防護(hù)1

1、集成電路I/O設(shè)計授課教師：趙毅強(qiáng)、陳霏2014年秋419周，周四下午15:5517:3026樓B109課程提綱 集成電路封裝Packaging CMOS電路的ESD保護(hù) ESD介紹 集成電路的ESD保護(hù) ESD保護(hù)在高速及RF電路的應(yīng)用 I/O Buffer設(shè)計2ESD介紹ELECTROSTATIC DISCHARGE3摩擦生電 When 2 Surfaces in Contact then Separate Some Atom Electrons Move Causing ImbalanceElectroStatic Charge 靜電起源4One Surface Has Positive

2、 Charge & One Surface Has Negative ChargeElectroStatic Charge 靜電起源5靜電的極性6 Air and human skin are capable of carrying the most positive charge Silicon rubber, teflon and silicon are capable of carrying the most negative charge靜電的儲存7 Insulators, due to their very high resistance, are capable of storin

3、g a huge amount of electrostatic charge Conductors, due to their very low resistance, are not able to store any charge陶瓷雙列直插式外殼帶點(diǎn)人體的靜電場85,000 Volts4,000V3,000V2,000V Charges Seek Balance Discharge is Rapid Creating Heat靜電的放電9Electrostatic Electrostatic Discharge or ESDDischarge or ESD Lightning Zap

4、from a door10 Walking across a carpet: Walking over untreated vinyl floor: Vinyl envelope used for work instructions: Worker at a bench: Unwinding regular tape: 11ESD的大小But To feel a Discharge it must be about 3,000 volts12ESD的人體感知濕度對ESD的改善13100 volts or less can damage components!14IC的ESD損害15SEMICO

5、NDUCTOR DEVICE SENSITIVITIES16Device TypeuMOSFETuVMOSuNMOSuGaAsFETuEPROMuCMOSuGaAsFETuJFETuSAWuOp-AMPuSchottky DiodesuFilm ResistorsuBipolar ResistorsuECLuSCRuSChottky TTLThreshold Susceptivity (Volts)10 - 10030 - 180060 - 10060 - 2000100+200 - 300025 - 50140-7000150-500190-2500300-2500300-3000300-7

6、000500+500-1000500-2500Example of ESD Damage Optical photo of a large Integrated Circuit which has experienced ESD damage to the pin noted by the arrow.17Example of ESD Damage Higher magnification photo of pin noted by the arrow in the prior slide This taken at 400 times magnification on a 4 X 5 pho

7、to. The damage is noted as the fuzz at the end of the arrow.18Example of ESD Damage Overlying glassivation has been removed and the surface decorated to show the ESD damage at 5,000 times magnification in this scanning electron micrograph.19Ranking of Semiconductor Failure CausesEOS/ESD is the #1 Ca

8、use ofSemiconductor FailureSource : Semiconductor Reliability News, March 1993EOS/ESD 59%Electrical testing 3%Oxide/passivationfailure 3%Conductor failure 3%Die fracture 4%Lead short/open 7%Wire bonds 15%Others 6%EOS: Electrical OverstressedESD: Electrostatic Discharge20EOS和ESD的關(guān)系EOS is usually divi

9、ded into three categories 1. EOS specific: In this category a relatively small voltage (i.e. 16V) is applied to the device for a long period of time (i.e. 1-10ms). In this category the delivered power is low. 2. ESD: In this category a high voltage (i.e. 1-15kV) is applied to the device in a short p

10、eriod (i.e. 1-100ns). The delivered power in this category is low as well. 3. Lightning: This category involves extreme high voltage and power. 21ESD失效的模式22DAMAGE MODESCatastrophic Failure Device no longer operates Are mostly caught in-house Represents 10% of ESD failuresIntermittent / Walking Wound

11、ed Device is operational, but erratic and will cause additional service calls Most expensive static problem Represents 90% of ESD failuresESD損害的代價23Component LevelBoard LevelSystem LevelField Service Level$5$500$50$5000ESDESD的模型24Human Body Model (HBM)25The protection level 24 kVCharged Device Model

12、 (CDM)26The protection level 5001200 Vfor the TQFP package is 750Vfor the uBGA package is 1200V Electronic Component ESD Sensitivity Electronic Component ESD Sensitivity (ESDS)(ESDS)Human Body Model (HBM)ESD Class 1: Damage you cant feel: ESD Class 2:Damage you might feel:ESD Class 3:Damage you can

13、probably detect as spark with your own body:200 to 1,999 Volts2,000 to 3,999 Volts4,000 to 15,999 VoltsESD Class 0:Damage you cant feel:0 to 199 Volts27CDM vs. HBMHBM: Deliver the lowest power over the longest time. Produces the largest heat damage to the part. CDM: It is very fast and delivers the

14、highest power to the part.Damage occurs typically at the core of the IC and hard to detect (very small).IC manufacturers calculate that about 90% of the failures from the field are due to CDM ESD events.28Tiny Conductive Paths Can Tiny Conductive Paths Can Easily Be DamagedEasily Be DamagedSmaller c

15、omponents mean greater sensitivity to ESD. Damage to these components can not be detected by the naked eye. Integrated Circuit29ESD失效的原因 High current densities: causes high power dissipation in semiconductor devices. The lattice temperature increases - thermal damage. Si has a negative resistance re

16、lationship with temperature -even higher power dissipation in a small volume - higher temperature and thermal runaway High electric field intensity: refers to the voltage developed across the dielectric and junctions CMOS gate oxide is the thinnest dielectric, it is the most vulnerable dielectric to

17、 ESD damage This damage is in the form of oxide breakdownIn soft breakdown (Walking Wounded), the performance is OK, but the leakage is increased After hard breakdown (Catastrophic), a current path is created from the gate to the channel and the transistor is destroyed30Oxide Rupture (Breakdown) In

18、sub-micron CMOS, due to very thin oxide dielectrics, gate oxide breakdown is the most common ESD failure31柵極氧化層擊穿趨勢32Junction Filamentation and Spiking33When silicon melts, its resistance drops by a factor of 30 or moreMetallization and Polysilicon Burn-out Metal wires (金屬連線), Poly Resistor (電阻) mus

19、t be made wide enough to handle an ESD current pulse34The Basics Of ESD ControlThe Basics Of ESD Control Ground Conductors Shield ESDS When store or transport outside EPA Neutralize insulators with ionizers35Personal GroundingWrist Straps and Coil CordsnWrist Straps ground personnel at workstationsH

20、eel GroundersnGround mobile personnel in areas where there are ESD floorsSmocksnSmock sleeves should be in contact with the skin, clothing underneath should not show36Personal GroundingAll Personal Grounding Equipment Should be Tested or Monitored DailynWrist Strap and Footwear Testing StationsnESD

21、ground monitoring nConstantnImpedance OHM Metrics and Monroe ElectronicsTest and Measurement ProductsCM Series ESD Workstation Monitors37 Wrist StrapsGround Conductors Including People Foot Grounders38Equipment GroundingWork Stations and TablesnMust have static dissipative surfaces connected to the

22、building ground source.nMust have wrist strap ground connections (2 recommended), preferably banana jack receptacles, connected in parallel to the bldg ground sourcenShould be cleaned daily with an antistatic cleaner39Ground All Conductors in ESD Protected Area Dissipative WorkSurfaces Ground ESD wo

23、rksurface via ground cord to common point ground to equipment ground Conductive Floor Mats Ground ESD floor mats via ground cord to equipment ground40Equipment GroundingShelving and CabinetsnMust provide a grounded surface unless the parts remain fully enclosed within shielding-type packagingStorage

24、 BinsnAll parts bins and containers must be static dissipative or antistaticnWhenever practical, sensitive parts should remain in the original container until assembled41Shield ESD Sensitive Items Shield ESD Sensitive Items Outside Protected AreaOutside Protected AreaFaraday Cage Closed Metallized S

25、hielding BagCharges Kept on Outside of Package: Covered conductive tote box42ESDS Component Handling and StorageTo move ESDS parts or assemblies inside an ESD control area, use one of the following;Static dissipative containersStatic shielding containersConductive containers or board carriersGround

26、movable racksSurface Mount Devices SMD Boxes43Ionization Many times, equipment or objects(insulators) are unable to be grounded in which case air ionizers should be used. What is Ionization?Air Ionizers use a process called neutralization to remove static charge from insulators that cannot be grounded.nIonizers produce positively and negatively charged ions and floods ESD area with Ions. nIons are charged particles that are present in the air, and as opposites attract, charges will be neutralized over time. 44Types of Air IonizersnBench Top nIonizin