Fluctuations of Characteristics in Sub-0.1mum Thin Film SOI CMOS LSI Devices

薄膜SOI CMOS器件在未来的大规模集成电路器件中备受关注。当器件按比例缩小到0.1 μ m以下时，波动问题占主导地位。本研究的目的是研究在低于0.1 μ m的SOI MOSFET中器件特性的波动，并提出一种补偿这些波动的新技术。我们制备了薄膜SOI MOSFET。通过实验测量和仿真处理了波动问题。首先，讨论了SOI厚度波动与阈值电压波动之间的关系。结果表明，栅极宽度小于SOI厚度波动周期时，阈值电压波动较大。这一结果表明，极窄栅极宽度的SOI dram在未来将存在波动问题。其次，建立了SOI器件的标度方法，并基于标度理论讨论了SOI通道中掺杂原子的随机波动。结果表明，薄膜SOI器件可以在不增加杂质浓度的情况下缩小尺寸，并且由于随机波动引起的器件特性波动在SOI器件中比在本体器件中要小得多。

Thin film SOI CMOS Devices have attracted much attention for future LSI devices. When the devices are scaled down to sub-0.1mum regime, fluctuation problems are dominant. The purpose of this study is to investigate the fluctuations of the device characteristics in sub-0.1 mum SOI MOSFET and to propose a new technique to compensate these fluctuations. We have fabricated the thin film SOI MOSFET.The fluctuation problems are addressed by both experimental measurements and simulation. First, the relation between the SOI thickness fluctuations and threshold voltage fluctuations are discussed. It is elucidated that the threshold voltage fluctuations become larger when the gate width is smaller than the period of the SOI thickness fluctuations. This result suggests that the SOI DRAMs which have very narrow gate width will have the fluctuation problem in the future. Next, the scaling methodology for SOI device is developed and the stochastic fluctuations of dopant atoms in SOI channel is discussed based on the scaling theory. It is concluded that the thin film SOI devices can be scaled down without the increase in impurity concentration and that the fluctuations of device characteristics due to the stochastic fluctuations are much smaller in SOI device than in bulk devices.