静电防护设计原理与方法ppt课件.ppt

《静电防护设计原理与方法ppt课件.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、第11讲静电防护设计原理与方法1静电防护设计原理与方法11.1元器件防护设计11.2印制电路板组件防护设计11.3电子整机系统的防护设计211.1元器件防护设计输入端的防护设计3DesignConceptsWillshuntmostorallofthecurrentduringanESDeventCanbe:athickfieldtransistorasiliconcontrolledrectifier(SCR)anMOStransistorasimplepndiodeServestolimitthevoltageor

2、currentatthecircuitbeingprotectuntiltheprimarydeviceisfullyoperational.Canbe:asmallgroundedgateMOStransistoradiodebetweenthepadsandthepower/groundsuppliesCanbe:polysiliconn+diffusionp+diffusionn-well4ThickFieldDevice--thickoxideorfieldoxidedevice(FOD)--usedforte

3、chnologieswithfeaturesizes(rangingfrom3µmto1µm)ThreeDifferentcross-sections5MainDesignParametersoftheFODHBMfailurethresholdsincreaseasthechannellengthisdecreasedinthe7µmto2µmrange6DraincontactIncreased-saturate:reason:distancebetweentheheatsourceandthecontact(co

4、ntactclosetodiffusionedge—theproducedheatspreadtoheatthecontactmetalization—resultinalowerfailurevoltage)Impactofthecontactspacing:veryimportantfortheabruptjunctionprocesses,weakeffectforlightlydopeddrain(LDD)theeffectvirtuallyvanishesforsilicideprocessImproveth

5、ehotcarrierreliability7nMOSTransistors(FPDs)essentiallythinoxidedevicesasopposedtotheFODarealsocalledfield-plateddiodesorgated-diodesusedasaprimaryprotectiondevice,intechnologieswithfeaturesizesgreatedthan1µmnonsilicidedtechnologyturnaroundintheESDperformanceoft

6、henMOSdeviceatthe0.8µmtechnologynodefornon-silicideddevicesatthe1µmtechnologynodeforsilicideddevice8MaindesignparametersofnMOSandlayoutthetransistorchannellength(L)draincontact-to-gatespacing(DCG)thedevicewidth(notshown)Thesourcecontact-to-gatespacing(SCG)(notpl

7、aymuchofarole,oftenkeptatitsminimumdesignvalue.RFiscomposedofmetalfingerresistanceContactresistanceDiffusionsheetresistanceRs(parasiticresistance):AssociatewiththegroundbusthatconnectsthefingersofthedeviceMaintainingaminimumrateforRs/RFisimportantforobtainingthe

8、bestpossibleESDperformance.minimizingRswillgivemoreuniformcurrentdistribution9HBMESDperformanceinFPDsasafunctionofDCGdraincontactspacinghasalargeeffectfornonsilicided