Hydrostatic bearing, alignment apparatus, exposure apparatus, and device manufacturing method

摘要

A bearing surface (50) opposing a movable guide (21) of a hydrostatic bearing has a gas supply hole (52) which has an orifice with a diameter smaller than that of the outer shape of the bearing. Each of hydrostatic bearings (14, 24) incorporates a poppet valve (53) which can seamlessly change the flow resistance in the gas supply hole (52), an actuator unit (55) for linearly driving the poppet valve (53), and a guide mechanism (58) which guides the poppet valve (53) so as to set the poppet valve (53) in linear motion. The actuator unit (55) has, for example, coils (56) arranged on the movable side (the base of the poppet valve (53)) and permanent magnets arranged on the fixed side (a portion opposing the base of the poppet valve (53)). With this arrangement, the poppet valve (53) can be driven at high speed and high precision. The poppet valve (53) is driven in accordance with a command from a controller (51). A pressure (Ps) is applied to the poppet valve (53) as the back pressure. The pressure (Ps) is restricted by the poppet valve (53) and a bearing clearance and becomes a bearing mean pressure (p).