flashmemory测试简介.ppt

flashmemory测试简介.ppt

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Memory测试原理,Unit1:

IntroductiontoFlashTechnology,OverviewofMemoryDevices,Nonvolatile,RAM,DRAM,SRAM,EEPROM,ROM,EPROM,PROM,Volatile,FLASH,CourseContents,TwoBasicMemoryCategories,VolatileMemory易挥发存储器Dataislostwhenpowerisremoved.NonvolatileMemory非易挥发存储器Dataremainsevenwhenpowerisremoved.,VolatileMemory,RAMRandomAccessMemorySRAM-StaticRAMiscommonlyusedas640Kbcachememoryincomputers.DRAM-DynamicRAMiscommonlyusedforread-writememoryincomputers.,NonvolatileMemory,ROMReadOnlyMemory,ROM,areprogrammedinawaferfabandcannotbeerasedorreprogrammedinthefield.PROMProgrammableROMcanbereprogrammedinthefieldbyapplyinglargervoltageswithspecialequipment.EPROMErasablePROMcanbeerasedwithUVlightandreprogrammedwithspecialequipment.EEPROMElectricallyErasablePROMcanbeerasedwithhighervoltagesandreprogrammedinthefield.,NonvolatileMemory,NVRAMNonvolatileRAM（Flash）issmallerthanPROMs,lessexpensive,andeasiertoprogramanderase.MagneticMagneticdiskandtapecanbeeasilyprogrammedanderasedbyuser,butareslowerthanFlash.OpticalCDROMcanbeeasilyprogrammedbyuserbutisslowerthanFlash.,BenefitsofFlashMemoryChips,SmallerthanEPROMSandEEPROMSRequiresonlyonetransistorandastoragecapacitorperbitcell.Canbequicklyandeasilyerasedandreprogrammedwithouttheneedofspecialequipment.Excellentforuseincellphones,pagers,calculators,portabledigitaldevices,automotive,flightdatarecorders,andpersonalcomputers.,SimpleROMMemoryArray,SimpleDRAMMemoryArray,Capacitorcharged,Nocurrent,“0”,Capacitoruncharged,Currentflow,“1”,ActivateRowtoreadIfcapacitorwascharged,nocurrentflowsonbitlineIfcapacitornotcharged,currentflowsonbitlineBufferoncolumnsenseamps,SimpleEPROMMemoryArray,Asecond“floatinggate”servesasthestorageelementinanEPROM.,FloatingGate,Source,Gate,FloatingGate（electricallyisolated）isthestorageelementcharged=“programmed”neutral=“erased”,BasicFlashMemoryCell,FlashCellStructure-SimilartoEPROM,exceptElectrically-erasable,p+Substrate,ControlGate,FloatingGate,FlashCellOperation-ProgramModeChannelHot-ElectronInjection,GND,VG=+9.3V,VD=+4.5V,Source,Drain,FlashCellOperation-ProgramModeChannelHot-electronInjection,GND,VG=+9.3V,VD=+4.5V,Source,Drain,p+Substrate,ControlGate,FloatingGate,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,FlashCellOperation-ProgramModeIDSConduction&FloatingGateCharge（Q）,p+Substrate,GND,VG=+9.3V,VD=+4.5V,ControlGate,FloatingGate,Source,Drain,Logicstate“0”,FlashCellOperation-EraseModeNegativeGate-FNTunneling,p+Substrate,ControlGate,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,e-,Electrically-erasablechargefromgate,Source,Drain,Logicstate“1”,FlashMemoryBitThresholdVoltages,FlashArrayArchitecture（schematic）,Corememory（core）,FlashArrayCellAddressing,RowDecoder,ColumnDecoder,SourceSwitch,BasicMemoryDeviceInternalArchitecture,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,A0,A1,A2,A3,A4,A5,A6,A7,Memorycell,MemoryCellblock:

每个CELL存储data（1/0）AddressDecoderCircuitry：

地址译码以（A0）来选择不同的memorycellorblock进行读写操作。

Input/OutputI/O）circuitry：

是memoryCell和外界的输入输出接口，将data在（D0）与Cell间传输。

ControlCircuitry：

控制memoryCell工作状态的电路CE/OE/WE（ChipEnable/OutputEnable/WriteEnable）,Unit2:

DeviceTestingDCparametrictestACparametrictestFunctionalTest,DCparametrictest,ISVM：

ForcecurrentmessagevoltageVSIM:

Forcevoltagemessagecurrent,DCParametricTests：

测试AddressDecoder和I/O回路中Input/OutputBuffer的DC特性。

在DCTest中一般使用VSIM及ISVM的方法。

DCContactCheck开路/短路测试OPEN/SHORTInput/OutputLeakageCheck输入/输出漏电流测试INLEAK/OUTLEAKCMOSAutomaticSleepCMOS自动睡眠模式电流测试CMOSASMStandbyCurrentCheckDevice不工作时待机电流测试ICCSBOutputDriveVoltage&CurrentDevice电压及电流驱动能力测试VOH/VOL,DCParametricTestOPEN/SHORTestINLEAK/OUTLEAKTestCMOSASMICCSBTestVOH/VOLTest,OpenTest,Purpose:

测量devicepins是否correctlytoDUT/Testerchannel测量Device内部管脚是否有开路。

Groundallpins（includingVCC）;SetVoltageClamp3.0volts;UsingPMU,forcepositiveornegativecurrent,onepinatatime;Measureresultantvoltage;Failstest（open）iftheabsolutevoltagemeasuredisgreaterthan1.5V;,TestMethod,ShortTest,Purpose:

测试thedevicepins是否有短路TestMethod:

Groundallpins（includingVCC）;SetVoltageClamp3.0volts;UsingPMU,forcepositiveornegativeVoltage,onepinatatime;Measureresultantcurrent;Failstest（short）iftheabsolutevoltagemeasuredislessthan0.2V.,Definition,IIL-InputleakagelowThecurrentinaninputwhenitisforcedlowvoltage.,IIH-InputleakagehighThecurrentinaninputwhenitisforcedhighvoltage.,Whytest?

TheIILtestmeasurestheresistancefromaninputpintoVCC,IIHtestmeasurestheresistancefromaninputpintoVSS.Thetestinsuresthattheinputbuffersofferahighresistancewhenapply0vandVCC.,InputLeakageTest（INLEAK）,InputLeakageLowTest-IIL,TestMethod,ApplyVCCmax.Preconditioningallinputstologic