成像质量是光学光刻机的最主要指标,硅片调焦调平测量是光刻机控制成像质量的基础。为此建立了硅片调焦调平测量系统单个测量点的测量模型,并根据硅片形貌标准和集成电路尺寸标准,推导了近似运算规则,简化了曝光场高度与测量光斑在光电探测器上的位置之间的数学关系。运用最小二乘法和平面拟合曝光场曲面的方法,推导了基于多个测量点的曝光场高度和倾斜测量的数学模型。该模型能满足调焦调平实时测量和控制的需要,可用于测量精度优于10 nm的高精度调焦调平测量系统,能满足线宽小于100 nm投影步进扫描光刻机的需要。

Image quality is the key performance of the optical lithography tool and it relies on the performance of wafer focusing and leveling measurement system. A measurement model of single probe spot for focusing and leveling measurement system is established. The relationship formula of the height of exposure field and the position on sensitive detector is simplified according to the approximation calculation rules derived from wafer mapping standard and integrated circuit size standard. Height and tilts of the exposure field can be calculated on basis of multiple probe spots by using least square method and surface fitting with a plane. Comparing with traditional model, this model can analyze focusing and leveling measurement system with higher accuracy of 10 nm, and can be used in developing lithographic tool with less than 100 nm critical dimension.