The dependence of UMOSFET characteristics and reliability on geometry and processing
The dependence of UMOSFET characteristics and reliability on geometry and processing
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UMOSFET 特性和可靠性对几何形状和加工的依赖性
DOI：
10.1088/0268-1242/16/6/305
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发表时间：
2001
影响因子：
1.9
通讯作者：
S. Fonash
中科院分区：
文献类型：
--
作者：
S. Suliman;N. Gollagunta;L. Trabzon;J. Hao;R. Ridley;C. Knoedler;G. Dolny;O. Awadelkarim;S. Fonash
我们研究了沟槽处理和沟槽和器件单元几何形状对单个n沟道U形沟槽金属氧化物硅场效应晶体管(n-UMOSFET)和由多个n-UMOSFET组成的器件单元特性的影响。所考察的几何参数包括沟槽深度和宽度、沟槽横截面和器件单元间距。我们发现，几何形状对沟道中的电子迁移率没有影响，但几何形状对隔离器件或器件单元特性的影响表现在漏极端的扩展电阻上。沟槽处理，如沟槽刻蚀、沟槽清洗和随后的栅氧化层生长，被观察到主要影响n-UMOSFET对电应力的免疫力，这是通过电荷泵电流和栅氧化层击穿测量来研究的。结果表明，与漏极相邻的栅氧化层边缘和与漏极重叠的氧化层/硅界面是最容易受到Fowler-Nordheim应力退化的区域。这些观察结合扫描电子显微镜的结果表明，栅氧化层生长的不均匀性以及沟槽拐角处的条件是决定n-UMOSFET可靠性的关键因素。
We have examined the impact of trench processing and trench and device cell geometries on the characteristics of a single n-channel U-shaped trench metal-oxide-silicon field-effect transistor (n-UMOSFET) and a device cell comprising several n-UMOSFETs. The geometrical parameters investigated included the trench depth and width, the trench cross-section and the device cell pitch. We have found out that the geometry does not affect the electron mobility in the channel; however, the effects of the geometry on the characteristics of the isolated device or device cell are manifested on the spreading resistance of the drain end. Trench processing, in the form of trench etching, trench cleaning and subsequent gate-oxide growth, is observed to primarily influence the n-UMOSFET's immunity to electrical stress, which is studied using charge pumping current and gate-oxide breakdown measurements. It is shown that the gate-oxide edge adjacent to the drain and the oxide/silicon interface overlapping the drain are the regions most susceptible to degradation by Fowler-Nordheim stress. These observations coupled with results from scanning electron microscopy suggest that the gate-oxide growth non-uniformity as well as its condition at the trench corners are the key factors in determining the n-UMOSFET's reliability.