Research On ESD-induced Soft Failure For Smartphone Camera Sub-system

Electrostatic discharge(ESD)soft failure is a phenomenon that non-destructive functional failure occurs on the electronic device system due to the gathering and discharging of static electrical charges.The ESD soft failures can be recorrected by system's self-correction or intervention from the operator.However,the non-destruction of ESD soft failure also makes difficulties on tracing discharge current,identifying noise coupling and seeking root cause.With higher popularity of portable electronic devices,system-level ESD soft failures are more and more reported.The ESD soft failures have been seriously affecting the experience when using these devices.In order to reduce the probability of system-level soft failures caused by ESD,and to improve the experience under system-level ESD,research on system-level ESD soft failures is gradually being paid more attention.System-level ESD soft failures may occur in different devices,and the failure phenomena are different among different scenarios.Identifying system-level ESD soft failure harzads in simulation is important for the protection of ESD soft failures.Descrbing the soft failures with certain electrical parameters is a prerequisite for simulating soft failures in circuit software or EM simulation platform.Since the appearance of system-level ESD soft failures is a probability issue,it is significant to reproduce the soft failures during the test.Systemlevel soft failure simulation also requires the characterization of pins of all devices and the ICs.For solving the problems mention above,this paper studies the soft failure characterization test of the camera subsystem on a specific smartphone model.And this paper also proposes a TVS behavior model and verifies the model accuracy through simulation.In addition to the problem that equipment manufacturers can not obtain the response under different pulses,this paper proposes a general method to model the characterization of pins based on ESD response of each pin.The contents are summarized and innovation are highlighted as following.(1)This paper presents a method for ESD soft failure characterization.Based on the TLP generator,this paper proposes a method to characterize the ESD soft failure of the camera subsystem,including the environment,test set-ups,and test parameters.During the test,the controllable TLP source is used to characterized the soft failure on each lane of the camera subsystem to obtain the soft failure baseline.In addition,the effect of the pulse interval on the soft failure probability with respect to voltages is studied.(2)This paper also proposes a TVS behavior modeling method,and optimizes the TVS devices with ultra-low turn-on resistance specially.The modeling method including parameter extraction,parameter fitting and model architecture.Both static characteristics and transient characteristics of TVS devices are including in this method,which is suitable for both diode-like TVS and snapback TVS devices.In addition,a special model for ultra-low on-resistance TVS devices is also proposed.(3)A pin behavior model based on ESD characteristics is also proposed.In view of the absence of IC models from the IC manufacturer,this paper proposes a model based on pin behavior under the pulse,since that the chip's on-chip ESD protection network bears most of the current under the ESD pulse.The model was verified by caomparing the simulation result with TLP measurement result.