Nano-machining in a Scanning Electron Microscope by Run-to-Run Control Based on Image Feedback

• Main Authors: Yu-Jhu Lin, 林玉珠
• Other Authors: Jeng-Sheng Huang
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/95926541815777953038

碩士 === 中原大學 === 機械工程研究所 === 96 === The purpose of this research is to perform nano-machine in a scanning electron microscope (SEM) via the run-to-run control and digital image feedbacks. The digital images are obtained by using the wavelet transform and binarization in order to recognize and feedback the digital image information to the picomotor controller; and then obtain the next input data for the actuating controller to achieve the targeted machining precision. To the aforementioned goal, assume first that the nano-machine is a single input single output system and it is a linear relation between inputs and outputs. The control method used is the widely-used Run-to-Run Control (Exponentially Weighted Moving Average) for semiconductor manufacturing processes. This controller is capable of compensating the machining inaccuracy induced by the picomotor drives. Furthermore, efforts are paid to estimate and adjust next control input based on the former input and output data. In this process, an appropriate discount factor values is chosen to quickly reduce the error and converge to the targeted precision. The experiment verifies that the designed controller and the associated factors can reduce the error of the nano-machining process from 40% to 0.7%.