Dependence of the quality of adhesion between poly(dimethylsiloxane) and glass surfaces on the composition of the oxidizing plasma
Dependence of the quality of adhesion between poly(dimethylsiloxane) and glass surfaces on the composition of the oxidizing plasma
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DOI：
10.1007/s10404-010-0724-y
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发表时间：
2011-04-01
影响因子：
2.8
通讯作者：
Vullev, Valentine I.
中科院分区：
文献类型：
--
作者：
Chau, Kenny;Millare, Brent;Vullev, Valentine I.
聚二甲基硅氧烷(PDMS)的受控表面氧化是由该弹性体组成的器件组件之间永久粘接的关键。这种微器件组件之间的永久粘合是由于PDMS和其他基于二氧化硅的材料(如玻璃、石英和PDMS)之间的界面上的共价交联造成的。通过含氧等离子体处理获得的最佳氧化时间和条件，对于具有定量产量的微细加工过程至关重要。虽然PDMS氧化不足并不能提供足够高的硅氧基表面密度用于跨界面连接，但PDMS的过度氧化会产生粗糙的二氧化硅表面层，从而防止平面衬底之间的粘合。理想情况下，对于一组等离子体条件，产生永久粘合的处理时间范围应该尽可能宽：即，在过氧化影响变得明显之前，足以进行不可逆结合的PDMS的表面氧化必须显著完成。这样的要求确保了处理条件中相对较小的波动不会导致氧化过度或氧化不足，因此不会损害制造过程的成品率。我们考察了经等离子体处理的PDMS与玻璃基板之间的粘接质量(QA)与含氧等离子体的组成以及等离子体发生器的射频(RF)之间的依赖关系。我们观察到，在兆赫射频产生的等离子体提供了比千赫射频更好的条件。与此同时，用于血浆的二元混合气体含氧量的增加，延长了提供卓越质量保证的治疗持续时间。
Controlled surface oxidation of polydimethylsiloxane (PDMS) is essential for permanent adhesion between device components composed of this elastomer. The permanent adhesion between such microdevice components results from covalent crosslinking across the interfaces between PDMS and other silica-based materials, such as glass, quartz, and PDMS. Optimal duration and conditions of oxidation, attained via treatments with oxygen-containing plasma, are crucial for microfabrication procedures with quantitative yields. While insufficient PDMS oxidation does not provide high enough surface density of siloxyl groups for cross-interface linking, overoxidation of PDMS yields rough silica surface layers that prevent the adhesion between flat substrates. Ideally, for a set of plasma conditions, the range of treatment durations producing permanent adhesion should be as broad as possible: i.e., the surface oxidation of PDMS sufficient for irreversible binding has to complete significantly before the effects of overoxidation become apparent. Such a requirement assures that relatively small fluctuations in the treatment conditions will not result in over- or under-oxidation and, hence, will not compromise the yields of the fabrication procedures. We examined the dependence of the quality of adhesion (QA) between plasma-treated PDMS and glass substrates on the composition of the oxygen-containing plasma and on the radio frequency (RF) of the plasma generator. We observed that plasma generated at megahertz RF provided superior conditions than kilohertz RF. Concurrently, an increase in the oxygen content of binary gas mixtures, used for the plasma, broadened the treatment durations that afford superior QA.