In this paper, a new pre-alignment approach based on Four-Quadrant-Photo-Detector （FQPD） for IC mask is presented. The voltage outputs from FQPDs are the functions of alignment mark＇s position offsets with respect ...In this paper, a new pre-alignment approach based on Four-Quadrant-Photo-Detector （FQPD） for IC mask is presented. The voltage outputs from FQPDs are the functions of alignment mark＇s position offsets with respect to FQPDs. The functions are obtained with least squares error （LSE）-based polynomial fitting after the normalization of experimental data. As the acquired functions are not monotonic about their variables, the alignment mark＇s position offset cannot be given by direct inverse operation on the obtained functions. However, the piecewise polynomial fitting gives the inverse function, with which the alignment mark＇s position offset can be predicted according to the voltage outputs of FQPDs. On the basis of prediction, a pre-alignment control strategy is proposed. The feasibility and robustness of the pre-alignment approach is shown by experiments. Furthermore, the results demonstrate that the maximum error of mask＇s position offset in the X- and Y- directions is less than 15μm after coarse pre-alignment. Keywords： Four-Quadrant-Photo-Detector （FQPD）, pre-alignment, IC mask, polynomial fitting展开更多
System Four是第五代数字地震仪,其先进的功能和庞大的带道能力预示着地震勘探技术的又一次飞跃。仪器参数的选择在保证地震采集资料质量上作用很大,特别是前放增益参数的选择直接关系到资料品质的好坏。本文详细论述了使用常规速度型...System Four是第五代数字地震仪,其先进的功能和庞大的带道能力预示着地震勘探技术的又一次飞跃。仪器参数的选择在保证地震采集资料质量上作用很大,特别是前放增益参数的选择直接关系到资料品质的好坏。本文详细论述了使用常规速度型检波器时,System Four(AC)前放增益的选择原则和分析方法,为复杂构造和复杂地表地区的野外地震资料采集施工提供一种分析思路,即在保证信号不溢出的前提下选择增益应按由高到低的顺序进行。展开更多
基金This work was supported by National High Technology Research and Development Program of PRC (No. 2002AA420040)National 973 Program of PRC (No. 2002CB312200).
文摘In this paper, a new pre-alignment approach based on Four-Quadrant-Photo-Detector （FQPD） for IC mask is presented. The voltage outputs from FQPDs are the functions of alignment mark＇s position offsets with respect to FQPDs. The functions are obtained with least squares error （LSE）-based polynomial fitting after the normalization of experimental data. As the acquired functions are not monotonic about their variables, the alignment mark＇s position offset cannot be given by direct inverse operation on the obtained functions. However, the piecewise polynomial fitting gives the inverse function, with which the alignment mark＇s position offset can be predicted according to the voltage outputs of FQPDs. On the basis of prediction, a pre-alignment control strategy is proposed. The feasibility and robustness of the pre-alignment approach is shown by experiments. Furthermore, the results demonstrate that the maximum error of mask＇s position offset in the X- and Y- directions is less than 15μm after coarse pre-alignment. Keywords： Four-Quadrant-Photo-Detector （FQPD）, pre-alignment, IC mask, polynomial fitting
