SPATIALLY RESOLVED ELECTRICAL MEASUREMENTS OF SIO2 GATE OXIDES USING ATOMIC FORCE MICROSCOPY
SPATIALLY RESOLVED ELECTRICAL MEASUREMENTS OF SIO2 GATE OXIDES USING ATOMIC FORCE MICROSCOPY
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DOI：
10.1063/1.108579
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发表时间：
1993-02-15
影响因子：
4
通讯作者：
VERHAVERBEKE, S
中科院分区：
文献类型：
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作者：
MURRELL, MP;WELLAND, ME;VERHAVERBEKE, S
利用改进的原子力显微镜（AFM）与导电悬臂梁，我们研究了SiO2栅氧化膜的介电强度。这已经实现了通过空间解析的预击穿之间的硅衬底和尖端的隧道电流流动。在AFM成像期间，在每个图像点处将电压斜坡施加到尖端，以便确定在氧化物中产生小的隧穿电流所需的局部阈值电压，而不会引起不可逆的电击穿。对于12 nm厚的氧化物，发现该电压在0.14 mum 2的面积上变化超过2.7倍，最大值为40.5 V。这表明传统金属氧化物硅电容器的击穿强度可能不受氧化物的固有介电强度的限制，而是受Si/SiO2结构中的缺陷或不均匀性的限制。通过防止在扫描过程中不可逆的氧化物击穿，我们可以成像的氧化物薄膜的介电性能的横向分辨率优于20 nm。
Using a modified atomic force microscope (AFM) with a conducting cantilever, we have investigated the dielectric strength of SiO2 gate oxide films. This has been achieved by spatially resolving the prebreakdown tunneling current flowing between the silicon substrate and tip. During AFM imaging a voltage ramp was applied to the tip at each image point so as to determine the local threshold voltage required to generate a small tunneling current in the oxide, without causing an irreversible electrical breakdown. For an oxide 12-nm thick this voltage was found to vary by more than a factor of 2.7 over an area of 0.14 mum2, with a maximum value of 40.5 V. This suggests that the breakdown strength of conventional metal-oxide-silicon capacitors may not be limited by the intrinsic dielectric strength of the oxide, but by imperfections or nonuniformities in the Si/SiO2 structure. By preventing irreversible oxide breakdown during scanning, we can image the dielectric properties of oxide films with a lateral resolution better than 20 nm.