Fabrication of Two-Dimensional Microstructures by Using Micro-Anode-Guided Electroplating with Real-Time Image Processing

Abstract

The purpose of this research was to develop a new micro-anode-guided electroplating (MAGE) system equipped by an image-guided positioning controller, to fabricate two-dimensional microstructures. From real-time image, the relative positions of the micro-anode and the microstructures tip can be located and maintained. When the relative position is adjusted, the deposition direction of the microstructures can be controllable and microstructures with different geometries can be fabricated.During past decades, the fabrications of 3D microstructures and nanostructures have been attracting attention because of their applications in biosensors, gas sensors, thermal couples, and 3D integrated chips. Many processes have been proposed to produce 3D micro-and nanostructures, such as Lithographie Galvanoformung Abformung (LIGA), 1 localized electrochemical deposition (LECD), 2 mask projection micro-stereo lithography, 3 track-etch method, and laser-assisted chemical vapor deposition (LCVD). 4 Among these techniques, LECD has the advantages of being an inexpensive, mask-less, low-power, and easy-to-design technique. 5-12 Furthermore, LECD can be applied to multiple materials such as metals, metal alloys, piezoelectric material, conducting polymers, and semiconductors. 13 New methods have been proposed to improve the performance of LECD; these include micro-anode-guided electroplating (MAGE), 14 deposition-detection-withdrawal (DDW) control method, 15 and realtime image-guided micro-anode electroplating system. MAGE has demonstrated that the micro-anode can be controlled to move in either continuous or intermittent mode to guide the progress of Nielectroplating; 14 hence, it influences the surface morphology of the electroplated microstructures. Although the resulting microstructures are less porous, their surface is rough and nodular. To improve the surface quality of microstructures by employing the MAGE process, C.S. Lin proposed a DDW control method, 15 which could prevent the possible contact between the microstructures and the micro-anode. However, the resulting surfaces are not uniform because the deposition rate is not constant as it is affected by electric field that is applied on surface of the microstructures. 16 Moreover, the variation of the electric field owing to the variation in the gap between the anode and microstructure cannot be controlled by employing the MAGE process or DDW control method. To address all these problems, a MAGE system with real-time image processing was proposed to create a steady electric field on the microstructure surface proposed. 17 This system stabilizes the distance between the anode and the microstructure on the basis of measurements based on from real-time imaging, ensuring that the formed column structures are smooth with no pores, uniform, and straight. Moreover, the diameter of the microstructure can be controlled by adjusting different parameters, such as applied voltage and the distance between the anode and the microstructure. 18 Most previous studies 13-21 mainly focused on...

Fabrication of 3D Microstructure by Localized Electrochemical Deposition with Image Feedback Distance Control and Five-Axis Motion Platform

“…In the shifted anode control method, the tip of the microstructure was placed away from the central axis of the micro anode, as reported in the previous study. 15 The parameters of this method in the 3D cylindrical coordinate system were specified by ρ, θ, and Z. To transform the parameter ρ and Z could adjust deposition direction angle.…”

“…The method to determine the position of the anode and cathode is the same as our previous research. 15 Then, the algorithm controlled the 3-axis motion platform to steer the cathode on a 3D curve.…”

“…The placement of anode and cathode in our technique is different from a typical LECD system. 5,9,[15][16][17] In a typical LECD system, the micro anode is usually fixed on the top of the tank, and the tip of the micro anode is immersed in the electrolyte. The cathode is fixed at the bottom of the plating cell, which in turn can be moved by the motion platforms.…”

“…Second, previous research revealed that the design of platinum surfaces can affect the deposition on a 2D plane. 15 The asymmetric anode had two perpendicular platinum surfaces that were wider than the flat micro anode had, therefore, enlarging the extent of the deposition direction angle.…”

“…Utilizing this technique, shifted anode control method for fabricated high quality 2D microstructures was also made possible. 15 The shifted anode control method was to control and main-tain the deposition direction angle in two direction. By this method, LECD process allowed fabrication of microstructures with different types of 2D geometries.…”