【摘要】 本文使用计算机模拟技术,研究了SOI结构中各部分的电势分布和载流子分布.模拟结果表明:对于有均匀掺杂的P型再结晶硅膜的SOI结构,当硅膜厚度小平相应的最大耗尽层厚度时,会出现“薄体效应”.它表现为:在内层氧化层厚度一定时,再结晶膜愈厚,阈电压愈高;在再结晶膜厚度一定时,内层氧化层愈厚,阈电压愈低,最后达到一个定值,与内层氧化层的厚度无关.正界面电荷进一步降低了由P型再结晶膜构成的SOI结构的阈电压.模拟计算表明,为使SOI结构不出现薄体效应,设计原则就是使适当掺杂的再结晶膜厚度大于最大耗尽层厚度.在硅膜厚度小于最大耗尽层厚度时,为使薄体效应的影响减小,应该采用比较低的硅膜掺杂浓度,比较厚的内层氧化硅层.模拟计算表明,利用薄体效应,可以形成以单晶硅为衬底的,阈电压较低的新型薄膜MOS晶体管.模拟计算还表明,对于薄硅膜的SOI结构,用耗尽层近似推出的阈电压公式是一个简单和比较准确的公式.更多还原

【Abstract】 The potential and carrier distribution in different parts of SOI structure are stu-died by using computer simulation.The resuats show that thin bulk effects occur in SOlstructure,with uniformly doped P-type recrystallization silicon film,when the thicknessof the film is less than the maximum thickness of the depletion layer.The higher thethreshold voltage the thicker the recrystallization film when the thickness of the innerdioxide is constant;whereas the lower the threshold voltage the thicker the inner dioxidewhen the film thickness is constant.The threshold voltage decreases as the inner dio-xide thickness increases and finally becomes a constant value not dependent on the th-ickness of inner dioxide.The interface states with positive charge in SOI structure fur-ther decrease the threshold voltage.Simulation analysis show that the principle designrule to prevent thin bulk effects in SOI structure is to make the thickness of the recrys-tallization film exceed the maximum thickness of the depletion layer, and to use lowdoping density silicon films and thick inner dioxide so as to decrease the influence ofthin bulk effects when the film, thickness is less than the maximum thickness of thedepletion layer.The simulation presupposes that it is possible to develop new MOS thinfilm transistors with crystal silicon substrate and lower threshold voltage.The simula-tion shows that the expression of threshold voltage for SOI structure,using depletion ap-proximation,is very simple and more accurate.更多还原