Soft matter beats hard matter: rupturing of thin metallic films induced by mass transport in photosensitive polymer films.
Soft matter beats hard matter: rupturing of thin metallic films induced by mass transport in photosensitive polymer films.
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DOI：
10.1021/am400682w
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发表时间：
2013-08
影响因子：
9.5
通讯作者：
N. S. Yadavalli;F. Linde;Alexey Kopyshev;S. Santer
中科院分区：
文献类型：
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作者：
N. S. Yadavalli;F. Linde;Alexey Kopyshev;S. Santer
金属薄膜和聚合物材料之间的界面在现代柔性微电子中起着重要的作用，即聚合物基板上的金属接触，印刷电子和假体装置。金属-聚合物界面研究的重点是研究聚合物衬底的外应力如何导致金属薄膜的变形和裂纹，反之亦然。通常，由于局部缺陷处的应力过大，变形过程涉及在大横向尺寸上变化的应变。在这里，我们表明在宏观尺度上看似随机的现象可以在亚微米尺度上变得相当可控。最近，我们创造了一种金属-聚合物界面系统，其应变在几百纳米的周期内变化。这是通过利用含偶氮苯的光敏聚合物薄膜在光干涉模式照射下形成的表面浮雕光栅（SRG）来实现的。在厚度达60纳米的情况下，被吸附的金属膜整齐地适应了形成的起伏，直到它最终破裂成一排条纹，形成高度规则和均匀的裂缝，沿着聚合物地形的最大值和最小值。这一令人惊讶的现象有着深远的影响。这是第一次使用直接探针来估计玻璃状聚合物中SRG地层中出现的力。此外，可以在慢动作中研究薄金属薄膜中的裂纹形成，这可能会导致柔性电子产品设计过程的实质性改进。最后，裂纹产生均匀且密度高，与常识相反。这可以为机械性质的精确纳米加工过程提供新的策略。
The interface between thin films of metal and polymer materials play a significant role in modern flexible microelectronics viz., metal contacts on polymer substrates, printed electronics and prosthetic devices. The major emphasis in metal-polymer interface is on studying how the externally applied stress in the polymer substrate leads to the deformation and cracks in metal film and vice versa. Usually, the deformation process involves strains varying over large lateral dimensions because of excessive stress at local imperfections. Here we show that the seemingly random phenomena at macroscopic scales can be rendered rather controllable at submicrometer length scales. Recently, we have created a metal-polymer interface system with strains varying over periods of several hundred nanometers. This was achieved by exploiting the formation of surface relief grating (SRG) within the azobenzene containing photosensitive polymer film upon irradiation with light interference pattern. Up to a thickness of 60 nm, the adsorbed metal film adapts neatly to the forming relief, until it ultimately ruptures into an array of stripes by formation of highly regular and uniform cracks along the maxima and minima of the polymer topography. This surprising phenomenon has far-reaching implications. This is the first time a direct probe is available to estimate the forces emerging in SRG formation in glassy polymers. Furthermore, crack formation in thin metal films can be studied literally in slow motion, which could lead to substantial improvements in the design process of flexible electronics. Finally, cracks are produced uniformly and at high density, contrary to common sense. This could offer new strategies for precise nanofabrication procedures mechanical in character.