Abstract Virtually complete charge transfer can be achieved with charge coupleddevices(CCDs)intheburiedchannelconfigurationbecausetheburiedchannelCCDintroduces no transfer noise. However, conventional charge detectors incorporatedinto CCDs have a comparably large noise, which consists of thermal noise and 1/fnoisefromMOS transistorin theoutputchargedetectors.
222Y.
MatsunagaFig.10.3Cross-sectionof oatingwelldetection
transistor
Fig.10.4Practical oatingwellchargedetectorfabricatedinshallowp-wellonn-typesubstratethickoxideisemployedforthedetectiontransistor’sgateoxide.A atpotentialplate(FPP),whichis oatingelectrically,isinsertedunderthedetectiontransistorgate(G).TheFPPsuppressesthetwo-dimensionaleffectwhichcausesapotentialpocketinthesensingchannel.Thetransferlossinducedbyapotentialpocketresultsintransfernoiseinthedetector.
Figure10.4showsapracticaloutputampli erfordetectingthecharge(electron)packetstransferredinathree-phaselinearCCDwhichisfabricatedinashallowp-wellonthen-typesubstrateof45 cmresistivity.Thepotentialcontrolgate(G)areawiththethickgateoxidelayermeasures5 5 m2,andthethingatelayerundertheFPPis93nmthick.ToformtheP-typechannelforthedetectiontransistor,alocaldeepboronimplantationthesensingchannelisrequired.Figure10.5shows
