摘要 |
A projection exposure apparatus has an exposure processing section for projecting and exposing an image of a pattern of a reticle on a photosensitive substrate, an environmental chamber for covering the exposure processing section and a fan unit for supplying a temperature-controlled gas to the environmental chamber. Exposure to the photosensitive substrate is carried out in a temperature-controlled atmosphere. The pressure of the gas in the environmental chamber is monitored by a pressure sensor. When the pressure is changed, the mixture ratio of the gas supplied to the environmental chamber is changed to keep the refractive index of the gas in the chamber constant thereby to prevent imaging characteristics of the projected image from deteriorating.
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