| 摘要 |
PURPOSE:To prevent a hot spot on a wafer surface and to make a pattern accurate by composing a collimator lens of the 1st meniscus lens which has a convex surface on the side of a light source and negative refracting power and the 2nd biconvex lens. CONSTITUTION:Luminous flux from the light source 1 is made incident on an optical element for multiple luminous flux generation to obtain the secondary light source. Further, a reflecting mirror 7 and the collimator lens 8 are provided. This collimator lens 8 consists of the 1st meniscus lens 8-1 which has the convex surface on the side of the light source and the negative refracting power and the 2nd biconvex lens 8-2. Further, a mask 9 is irradiated with the light to form a pattern on the wafer 10. Then, the lens 8 and mask 9 are held at proper distance to improve lighting effect and refractive indexes of lens elements of the lens are set within a specific range. Thus, parallel luminous flux is obtained by using the collimator lens, so the formation of a hot spot on the wafer surface is prevented to reduce an error in pattern line width.
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