光刻物镜偏心调节机构抑制耦合误差设计

Coupling Error Inhibition of Eccentric Adjustment Mechanism Design in Lithographic Objective Lens

为了找出耦合误差产生的根源,探讨了柔性偏心机构设计方法.首先,给出了机构组成和工作原理;然后,基于柔度矩阵法对机构建模,分别推导了桥式位移放大机构、导向机构、连接机构的柔度;最后,综合得到机构的整体柔度.分析结果表明柔度矩阵法得到的输出柔度理论值和有限元法得到的结果误差为8.126%,机构的一阶固有频率为73.78Hz.在40N的驱动力范围内,机构可以实现66.466μm的行程,透镜和机构上的最大应力分别为0.0711 MPa和235.22 MPa,Y/Z/RX/RY/RZ耦合误差和X向行程的比分别为0.0543%、0.0082%、1.218×10-8rad/μm、1.870×10-7rad/μm、6.073×10-7rad/μm.调节后镜片面形PV值优于24nm,RMS值优于5nm,并且主要为像散.通过合理的柔度设计,机构接近完全解耦,揭示了不合理的机构刚度是产生调节耦合误差的根源.

To identify the generated source of coupling errors, design method of the flexible eccentric mechanism is discussed in the paper. Firstly, the composition and working principle of the mechanism is given. Then, the mechanism model is established based on the compliance matrix method（CMM）. Compliance of the bridge-type displacement amplification mechanism, the guiding mechanism and the connecting mechanism is derived. Finally, compliance of the whole body is got. The results show that the output compliance error is 8. 126 % obtained by the CMM and FEA method. The first natural frequency of the mechanism is 73.78 Hz. The stroke of the mechanism is 66. 466μm when the driving force is no more than 40N. The maximum stress on lens and mechanism is 0. 0711MPa and 235. 22 MPa, respectively. The coupling error ratios between Y/Z/RX/RY/RZ and X stroke are 0. 0543 %, 0. 0082%, 1.218 ×10-8rad/μm, 1. 870× 10-7 rad/μm and 6.073 ×10-7 rad/μm. PV and RMS of the lens surface figure after adjusting are better than 24nm and 5nm, respectively. It is mainly astigmatism; The mechanism is almost completely decoupled by reasonable flexibility design, which reveals that unreasonable compliance is the root of the generated coupling errors in adjusting.