Research On The Fabrication Process And Key Characteristics Of Thin Film Transistors Based On Metal Oxides

Metal oxide thin film transistors(MO TFTs)are the current research hotspot.Compared with traditional?-Si TFTs,their properties are better.Among them,devices with IGZO as the active layer have high mobility and good light transmittance.It has the characteristics of good uniformity and stability,flexibility,and simple manufacturing process,so it has been widely and deeply studied and applied in such fields as display,detection,and biomedicine.The preparation of the active layer with different preparation process parameters,and the change of temperature or illumination in the environment will have different effects on the electrical properties of the device.In this thesis,the effects of the above aspects on the electrical properties of a single device are studied.The flexible IGZO-TFT arrays that can be used for sensing were further fabricated and tested.The main work is as follows:First of all,this thesis uses different process parameters to prepare a number of bottom-gate overlapped thin film transistors with IGZO as the active layer,Hf O₂ as the gate oxide layer,Al as the electrode,and silicon as the substrate,The transfer characteristic and output characteristic curve are obtained by testing,and the four performance parameters of threshold voltage Vth,mobility"?",current switching ratio Ion/Ioff and sub-threshold swing SS are tested,calculated and analyzed to evaluate the device.performance is good or bad.The experiment tested devices with different aspect ratios,active layer thicknesses,and different oxygen partial pressures when preparing the active layer.It was found that the device size with a width of 400"?m"and a length of100"?m"was used,and the active layer was grown by RF for 15min.The device performance is relatively good when the oxygen partial pressure is 0%.The device was then tested thermally and optically to verify its effect on the device.In terms of thermals,the temperature stability of the device is studied by testing the electrical properties of samples at different temperatures.At the same time,thermal tests were also carried out on IGZO-TFTs prepared with different oxygen partial pressures.Through experiments,it is found that with the increase of temperature,the output current of the device increases,the transfer characteristic curve shifts to the left,Vth decreases,"?"decreases,Ion/Ioff decreases,and SS increases.The temperature stability is worse.In terms of optics,when the device is irradiated with light of different wavelengths and intensities,the transfer characteristic curve of the device shifts to the left,Vth decreases,"?"decreases,SS increases,and the wavelength of the light used is shorter,The stronger the light intensity,the greater the impact on the device.Finally,a 16×16 flexible IGZO-TFT array was prepared.The single device adopts a bottom-gate planar structure.The source and drain electrodes of each column of TFTs are connected respectively,and the gates of each row of TFTs are connected to each other and are drawn out by metal wires,which is convenient for It is combined with other structures to form a complete circuit.The array was confirmed to work properly by testing its electrical characteristics and changing temperature and lighting conditions.And by judging its output value,the array can distinguish some simple graphics.