Fabrication of micropatterns on the sidewalls of a thermal shape memory polystyrene block
Fabrication of micropatterns on the sidewalls of a thermal shape memory polystyrene block
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DOI：
10.1088/0960-1317/20/9/095025
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发表时间：
2010-09-01
影响因子：
2.3
通讯作者：
Luo, Cheng
中科院分区：
文献类型：
--
作者：
Liu, Xinchuan;Chakraborty, Anirban;Luo, Cheng
目前微系统中的衬底侧壁还没有很好地应用于制造器件。另一方面，在这些侧壁上产生的图案可以作为垂直互连或3D电路中的电子元件。由于现有的光刻方法只能在侧壁上生成有限形状的图案，因此本研究开发了一种新的方法，通过聚苯乙烯薄膜的应变恢复变形来制造各种侧壁图案。制作过程包括三个基本步骤：第一应变恢复，压制和第二应变恢复。在制作过程中，聚苯乙烯经历的变形首先通过在样品上标记毫米尺度的线进行了研究。我们发现，压制，而不是横向拉伸，转移部分侧表面的聚苯乙烯块的部分顶部表面，并在压制后的加热能够转移相同的部分顶部表面到侧壁。研究了温度和恢复时间对聚苯乙烯变形的影响。我们确定了聚苯乙烯块的尺寸是如何随温度变化的。我们还研究了聚苯乙烯块在120摄氏度和160摄氏度下可以适当地经历多少次按压-回收循环。最后，将该方法应用于在聚苯乙烯块的顶面和侧面上生成Ag 50 x 50 μ m(2)点、150 μ m宽线和蛇形微电阻器，然后对这些产品进行表征，包括收缩和挤压变形、表面粗糙度、起皱变形和电阻变化。我们发现:(1)收缩变形可以粗略地认为是挤压变形的恢复，但由于两种变形形态不同，变形的大小不相同（即收缩变形受表面图案的影响，而挤压变形不受影响）；(2)当聚苯乙烯块体收缩变形较大时，表面图案可能产生褶皱；这可能会影响表面图案的功能，并导致，例如，它们的电阻降低。
Substrate sidewalls in the current microsystems have not been well used in building devices. On the other hand, the patterns generated on these sidewalls could serve as vertical interconnects or electronic components in 3D circuits. Since existing lithographic approaches could only generate patterns of limited shapes on the sidewalls, a new approach was developed in this work to fabricate various sidewall patterns via strain-recovery deformations of a polystyrene film. The fabrication procedure consisted of three basic steps: first strain recovery, pressing and second strain recovery. The deformations that the polystyrene experienced during the fabrication were first investigated with the help of mm-scaled lines marked on the samples. We found that pressing, instead of lateral stretching, transferred part of side surface of a polystyrene block into part of the top surface, and that the heating after the pressing was capable of transferring the same part of the top surface to the sidewall. The effects of temperature and recovery times on the deformations of the polystyrene were then investigated. We determined how the dimensions of a polystyrene block changed with the temperature. We also examined how many pressing-recovery cycles a polystyrene block could properly experience at 120 degrees C and 160 degrees C, respectively. Finally, the developed approach has been applied to generate Ag 50 x 50 mu m(2) dots, 150 mu m wide lines and serpentine-shaped microresistors on both top and side surfaces of polystyrene blocks, followed by the characterization of these products, including shrinking and pressing deformations, surface roughness, wrinkling deformations and resistance changes. We found: (i) the shrinking deformations could be roughly considered as the recovery of the pressing deformations, although the two types of deformations were not identical in magnitudes due to different configurations (i. e. the shrinking deformations were affected by surface patterns, while the pressing deformations were not), and (ii) wrinkles might arise in surface patterns when the polystyrene blocks had large shrinking deformations, which might affect the functionality of the surface patterns and cause, for example, the decrease in their resistances.