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提出一种新的步进扫描投影光刻机工件台方镜不平度测量方法。以方镜平移补偿量与旋转补偿量为测量目标,使用两个双频激光干涉仪分别测量工件台在x和y方向的位置和旋转量;将方镜不平度的测量按照一定的偏移量分成若干个序列,每一个序列包括对方镜有效区域的若干次往返测量;根据所有序列的测量结果计算出方镜的旋转补偿量;为每一个序列建立临时边界条件,并据此计算出每一序列所测得的方镜粗略平移补偿量;采用三次样条插值与最小二乘法建立每一个序列间的关系,以平滑连接所有测量序列得到精确的方镜平移补偿量。结果表明,该方法用于测量方镜平移补偿量,测量重复精度优于2.957 nm,测量旋转补偿量,测量重复精度优于0.102μrad。
A new method for measuring the squareness of the square mirror of stepper scanning projection lithography machine is proposed. Taking the square mirror translation compensation and rotation compensation as measurement targets, two dual-frequency laser interferometers were used to measure the position and rotation of the workpiece table in the x and y directions, respectively. The measurement of the squareness of the square mirror was performed according to a certain offset Divided into several sequences, each sequence including several round-trip measurements of the effective area of the other mirror; a rotation compensation amount of the square mirror is calculated from the measurement results of all the sequences; a temporary boundary condition is established for each sequence, and each The measured square mirror rough translation compensation amount; using cubic spline interpolation and least square method to establish the relationship between each sequence, in order to smoothly connect all the measurement sequence to obtain accurate square mirror translation compensation. The results show that this method is suitable for measuring the amount of square mirror translation compensation, the measurement repeatability is better than 2.957 nm, the amount of rotation compensation is measured and the measurement repeatability is better than 0.102 μrad.