一种沟槽型功率器件漏电的研究

One Type Leakage Study in Trench Power Device

随着环保意识以及节能需求的不断增加,功率器件的市场越来越大,沟槽型功率器件由于可以在有效的面积上形成较低的导通电阻,得到了广泛的应用。在良率测试中,漏电作为一个重要的参数,具有很多种可能的失效机制。研究一种经常出现于正方形元胞结构中、击穿电压正常但漏电却很高的特殊现象,给出"双MOS管"的漏电模型,立体结构中的侧棱部分决定了漏电的大小。通过模拟及实际流片,使用比较简单的调整阱注入的方式,验证模型的正确性,在维持击穿电压等参数不变的情况下,正方形元胞的漏电得到了极大的降低,获得了同条状型元胞同样的器件性能。虽以正方形元胞为例做了研究,但其理论模型和解决方案同样适用于其他具有多个侧面和侧棱的元胞结构,如六边形等。

With the increasing awareness of environmental protection and energy demand, power device market is getting bigger and bigger. Trench type power devices have been widely used due to its lower on-resistance. In yield test, leakage is an important parameter, and it has many potential failure mechanisms. This paper studies one special leakage which can happen frequently in square cell structures, the breakdown voltage is normal but the leakage is very high compared to strip cells. We propose a model as ＂double MOS combination leakage＂ where the edge of the polyhedron dominates the leakage level. Through simulation and actual product experiments, we uses a relatively simple method by tuning the well implant energy,dose and sequences,verified the correctness of the proposed model. The product with tuned process shows same breakdown voltage but the leakage of square cell has been greatly reduced. The performance is similar to that of strip cell. Although this study takes square cell as an example, its theoretical model and solution are also applicable to other cell structures like hexagon cell, etc..