An investigation on defect-generation conditions in immersion lithography
An investigation on defect-generation conditions in immersion lithography
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DOI：
10.1117/12.656441
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发表时间：
2006-03
期刊：
影响因子：
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通讯作者：
T. Tomita;T. Shimoaoki;M. Enomoto;Hideharu Kyoda;J. Kitano;Toshifumi Suganaga
中科院分区：
文献类型：
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作者：
T. Tomita;T. Shimoaoki;M. Enomoto;Hideharu Kyoda;J. Kitano;Toshifumi Suganaga
193-nm浸没式光刻技术是一种能够适应半导体缩小的光刻技术，它实现了高数值孔径（NA），并在曝光系统中使用去离子水作为透镜和晶片之间的介质，它的发展速度很快，并已达到实际应用的阶段。然而，关于在193 nm浸没式光刻的情况下引起关注的缺陷，许多组件仍然不清楚，并且许多问题仍然有待解决。例如，已经指出，在193-nm浸没式光刻的情况下，在曝光期间将抗蚀剂膜浸没在去离子水中导致湿气渗透到抗蚀剂膜中，抗蚀剂的内部成分溶解到去离子水中，并且在曝光期间产生的残留水影响后处理。此外，为了防止将抗蚀剂直接浸入去离子水中的这种影响，施加保护膜被认为是有效的。然而，即使施加这样的膜，仍然很可能仍然会出现上述缺陷。因此，为了减少这些缺陷，有必要通过使用某些种类的保护膜和抗蚀剂材料来识别在193-nm浸没光刻中出现的典型缺陷并了解缺陷产生的条件。此外，从现在开始，随着半导体的进一步缩小，对缺陷产生条件和临界尺寸（CD）之间的关系保持清晰的了解非常重要。为了提取193 nm浸没式光刻中出现的典型缺陷，作者与干法曝光光刻进行了对比研究，从而确认了与浸没式光刻相关的几种典型缺陷。然后，我们研究了在某些类型的保护膜的情况下产生缺陷的条件。除此之外，通过调查缺陷产生的条件并比较湿曝光和干曝光之间的分类数据，我们能够确定浸没式光刻中涉及的每个特定缺陷的来源。此外，湿处理和干处理的CD的比较可以指示未来的缺陷率水平，预计随着浸渍工艺临界尺寸的缩小。
As a powerful candidate for a lithography technique that can accommodate the scaling-down of semiconductors, 193-nm immersion lithography-which realizes a high numerical aperture (NA) and uses deionized water as the medium between the lens and wafer in the exposure system-has been developing at a rapid pace and has reached the stage of practical application. In regards to defects that are a cause for concern in the case of 193-nm immersion lithography, however, many components are still unclear and many problems remain to be solved. It has been pointed out, for example, that in the case of 193-nm immersion lithography, immersion of the resist film in deionized water during exposure causes infiltration of moisture into the resist film, internal components of the resist dissolve into the deionized water, and residual water generated during exposure affects post-processing. Moreover, to prevent this influence of directly immersing the resist in de-ionized water, application of a protective film is regarded as effective. However, even if such a film is applied, it is still highly likely that the above-mentioned defects will still occur. Accordingly, to reduce these defects, it is essential to identify the typical defects occurring in 193-nm immersion lithography and to understand the condition for generation of defects by using some kinds of protective films and resist materials. Furthermore, from now onwards, with further scaling down of semiconductors, it is important to maintain a clear understanding of the relation between defect-generation conditions and critical dimensions (CD). Aiming to extract typical defects occurring in 193-nm immersion lithography, the authors carried out a comparative study with dry exposure lithography, thereby confirming several typical defects associated with immersion lithography. We then investigated the conditions for generation of defects in the case of some kinds of protective films. In addition to that, by investigating the defect-generation conditions and comparing the classification data between wet and dry exposure, we were able to determine the origin of each particular defect involved in immersion lithography. Furthermore, the comparison of CD for wet and dry processing could indicate the future defectivity levels to be expected with shrinking immersion process critical dimensions.