Measurements of temperature distribution in polycrystalline thin film transistors caused by self-heating

Transient thermometry was applied to measure temperature distribution caused by self-heating in n-channel poly-Si TFTs on glass. Pt wires 30 nm thick were formed above the Al gate electrode via an intermediate SiO2 layer with positions above the drain edge, middle and the source as temperature sensors. Temperature above the drain edge increased 9 K from room temperature at a power consumption of 20 mu W/mu m per unit gate width, while it increased only 6 K above the source edge when the TFT was operated in a saturation mode. This results from heat generation being localized near the drain edge. The temperature change with time is also discussed.