Modeling Of Organic Thin Film Transistor And Integrated Circuit Design

Owing to advantages of materials and manufacturing processes of OTFTs,the progressively interesting of OTFTs focuses on the application in integrated circuits recently,such as Radio Frequency Identification?RFID?,which as a counterpart of traditional integrated circuit based on Silicon,and even become its substitute in the future.This work focus on the method of electronic design automation?EDA?of large scale organic integrated circuit?LSI?,and a SPICE-like model suitable for all types of OTFTs be present,different OTFTs be fabricated and the best be selected as the basic device to design and simulate the organic Analog-to-Digital converter circuits.The SPICE-like model of the best OTFT be built and H-SPICE be used to design and simulate the Analog-to-Digital converter circuits.Design result indicate the accuracy of the model of OTFTs,which can be used to the design of large scale organic integrated circuit and become the basis of design and fabrication of organic integrated circuits.First,accurate SPICE-like model suitable for all types of OTFTs be present.Many factors cause scattering in the characteristics of individual OTFT which causes is too Complex to be analysis physicaly,so the empirical formula of the effect mobility and empirical parameter ?a be used to describe the phenomenon ?FET rusually increases with gate voltage,the parameters ?a can be used to analyze physical mechanisms that take place in OTFTs.at the others,the resistance of the drain and source areas,leakage current across the gate dielectric,the effect of the channel length modulation,the effect of saturation modulation be considered to present a unified model with parameters include fitting parameters ?a,the characteristic voltage for field effect mobility Vaa,the minimum leakage current parameter SIGMAO,the channel length modulation parameter?,knee shape parameter m,the resistance of the drain and source areas?RD and RS?.the parameters in the unified model all can be extracted in a simple and direct way from the experimental measurements,then the model and it's parameters extracted method be applied to simulate the electronic characteristics of OTFTs we fabricated to verify their accuracy.Good agreement has been found between the simulated results and experimental measured results in both transfer characteristics and output characteristics.So the model and parameters extracted method be verified to be accurate in describing direct current characteristics of varieties of OTFTs.Second,different pentacene OTFTs with different Geometric dimensions and different gate dielectrics be fabricated and studied to select parameters can be design and best OTFT to be the basic device to design circuit.To study the effect of Geometric dimensions parameters of W/L?channel wide and length?and tox?thickness of gate dielectric?,the OTFTs used SiO₂ as gate dielectric,Pentacene as active layer be fabricated on Si.Research shows ?a>0 in all OTFTs and ?FET increasing with Vgs,which indicate the carrier conduction mechanism in OTFTs is mainly trap conduction mechanism,which similar to that of amorphous and nanocrystalline devices.If OTFTs with different thickness of gate dielectric,their parameters is different to each other and?FET can be increase with the decrease of tox,tox can not be select as the design parameter.If OTFTs fabricated with the same structure and the same thickness of gate dielectric,but different W/L of the channel,their parameters is very close to the others.So the OTFTs with different W/L of the channel can be used to design Organic integrated circuit with the same SPICE-like model,but the OTFTs with different thickness of gate dielectric or different gate dielectric material cannot use the same model with the same parameters.Next,we fabricated and studied OTFTs with different dielectric material and find that the OTFT fabricated with PVP as the dielectric material shows the best Characteristics by compare it's parameters to others',which was chose as the basic device of the organic circuit.Finally,the device based on PVP dielectric will be adopted as the basic device to design and simulate circuit because of it's most performance,with the parameters extracted from measured data,the SPICE-like model of OTFT with PVP dielectric be present,and a 4bit SAR?Successive approximation Register?ADC?Analog-to-Digital Converter?has been designed with the SPICE model of the device and H-SPICE software.The simulation results show that DNL and INL of prototype SAR ADC are both 0.55LSB,and SFDR,SNDR and ENOB are 31.5dB,21-dB and 3.2 bits,respectively.The ADC is composed of 409 OTFTs,and average current consumption of SAR ADC is 298uA when the supply voltage is 60V.Finally,the layout of the SAR ADC be present.It has been proved that the validity of modeling OTFT,which is suitable for organic integrated circuits design,and can forecast the performance of organic Large Scale integrated circuits.