The suction surface 7a of the stage 7 is provided with the fine suction groove 7b for attracting the wafer W. As shown in FIG. The suction groove 7b is divided into nine suction regions 61A to 61I, for example. The suction region 61I sucks the central portion of the circular wafer W. As shown in FIG. Suction regions 61A, 61B, 61C, 61D, 61E, 61F, 61G, 61H adsorb the peripheral portion of the circular wafer W. As shown in FIG. With respect to the wafer W held by the stage 7, gas is injected separately at nine positions corresponding to the suction areas 61A to 61I.
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