Mechanical Stress Effects on MOS Capacitors including FeRAM

1. 分别在1MHz和室温下测量了MOSn-MOS和p-MOS的电容。电容的变化可以用耗尽层宽度的变化和空穴带的态密度、有效质量的变化来解释。C-V曲线的斜率不会平行移动。C-V曲线不会伸展。介电常数、固定氧化物电荷和界面陷阱密度不变。几何变形不影响电容。解释了本征载流子密度的应力依赖性。FeRAMPt下电极沉积在MOS结构上。采用溶胶-凝胶法在电极上沉积PZT薄膜，在550℃下退火，薄膜厚度为220 nm。在其上沉积了直径为220 μm的Pt圆形电极。用索耶-塔电路在100khz的压力和压力下观察到磁滞回线。测量了残余极化应力系数、矫顽场和电容随电压的变化特性。电容随拉伸应力的增大而减小。

1. MOSn-MOS and p-MOS capacitances were measured at 1MHz, and at room temperature under tension and compression. Capacitance change can be explained by the change of depletion layer width through energy gap change and density of state effective mass change of hole bands. The slope of C-V curve doesn't displace in parallel. The C-V curve does not stretch-out.Dielectric constant, fixed oxide charge and interface trap density don't change. Geometric deformation does not affect the capacitance. The stress dependence of intrinsic carrier density was explained.2. FeRAMPt lower electrode was deposited on MOS structure. PZT thin film was deposited on the electrode by sol-gel method and annealed at 550 C. The thickness of the film is 220 nm. Pt circular electrode with 220 μm diameter was deposited on it. Hysteresis loops were observed by Saujer-Tower circuit at 100 kHz under tension and compression. The stress coefficients of residual polarization, coercive field and spcCapacitance vs voltage characteristics with tensile stress and without stress were measured. Capacitance decrease slightly with tensile stress.