Method for preventing electrostatic discharge in a clean room

#1. Field of the Invention

#The present invention provides a method for removing electrostatic charges from a clean room with a laminar flow apparatus, and more particularly, to a method for preventing electrostatic discharge in a clean room.

#2. Description of the Prior Art

#FIG. 1 is a schematic diagram of a method for preventing electrostatic charges in a clean room according to the prior art.

#FIG. 2 is a schematic diagram of a method for preventing electrostatic charges in a clean room according to the present invention

#Please refer to FIG. 2 of a schematic diagram of a method for preventing electrostatic charges in a clean room according to the present invention. As shown in FIG. 2, the present invention method for preventing electrostatic charges 100 in a clean room is to dispose an ionization system A 104 and an ionization system B 106 in the clean room (clean room not shown). Both the ionization system A 104 and the ionization system B 106 are fixed on a ceiling 102 in the clean room. However, output tips 112 of emitters 108 of the ionization system A 104 face toward a floor 114 in the clean room and output tips 112 of emitters 108 of the ionization system B 106 face toward the ceiling 102 in the clean room. The vertical distance between the output tips 112 of the emitters 108 of the ionization system A 104 and the ceiling 102 is approximately 84 CM. The vertical distance between the top plate 117 of the ionization system B 106 and the ceiling 102 is approximately 30 CM. The actual vertical distances between the output tips 112 of the emitters 108 of the ionization system B 106 and the ceiling 102 are calculated by subtracting the lengths of emitters 108 from 30 CM. The lengths of the emitters 108 are variable and are dependent on practical requirements and the specifications provided by vendors.

#An automatic transportation system A 116 and an automatic transportation system B 118 are disposed in the clean room. The two automatic transportation systems are overhead transport (OHT) systems. The automatic transportation system A 116 is usually disposed in the inter-tunnel aisle (the aisle between tunnel and tunnel). The vertical distance between the automatic transportation system A 116 and the ceiling 102 is approximately 86 CM. The automatic transportation system B 118 is usually disposed in the tunnel in the clean room. The vertical distance between the automatic transportation system B 118 and the ceiling 102 is approximately 36 CM. An old type cart 122, pushed manually, is disposed on the floor 114. The height (the distance-from the ceiling to the floor) of the clean room is approximately 3M. The automatic transportation system A 116 supports a carrier 124, and the automatic transportation system B 118 suspends the carrier 124. The carrier 124 may be a wafer carrier, a reticle carrier, or other carrier. Therefore, both the automatic transportation system A 116 and the automatic transportation system B 118 may be a wafer transportation system, a reticle transportation system, or other transportation system. A similar carrier 124, for transportating wafers or reticles, and other substances, are on the cart 122.

#When a positive voltage source and a negative voltage source are applied to each pair of emitters 108, compressed dry air is input into each pair of emitters 108 to generate positive charges and negative charges through ionization. The positive and negative charges flow downward, in the same direction as the laminar flow, to become a flow of positive ions 126 and a flow of negative ions 128 to neutralize the electrostatic charges 100 on the carrier 124 in the automatic transportation system A 116, the automatic transportation system B 118, and the cart 122.