Applying photoresist onto silicon wafers

Claim 1

Apparatus for applying photoresist to silicon wafers in the manufacture of integrated circuit chips, comprising enclosure means defining a closed chamber, the enclosure means including elongate peripheral walls and end walls traversing the peripheral walls and enclosing the chamber, an upright rotor in the chamber and revolving about an upright rotation axis extending transversely through the end walls, the rotor having elongate molded plastic carrier means with vertically spaced wafer edge supports for supporting such silicon wafers to lie transversely of the rotation axis in spaced and confronting relation to each other along and substantially concentric of the rotation axis, the carrier means having unobstructed openings at the sides thereof and extending vertically along significant portions of the length of the peripheral walls, each of the openings having a vertical length in excess of the vertical spacing between a plurality of the wafer edge supports and the spaces therebetween and each of the openings having a horizontal width of the same order of magnitude as the horizontal spacing between adjacent wafer edge supports to provide ready access to the wafers carried on the supports, and plurality of vertically spaced and horizontally directed nozzles in the chamber and adjacent the rotor, the nozzles being arranged in an upright row oriented endwise of the rotor, and being directed toward the rotor and rotation axis, and confronting the openings at the sides of the enclosure means to spray directly across and onto the wafers on the rotor, and a supply of photoresist connected to the nozzles for spraying onto the wafers, and the supply of photoresist including a closed measuring tank, and a valved source of high pressure gas under a continuing plurality of atmospheres of pressure and connected to the tank, the valved source being open and applying the continuing plurality of atmospheres to blow the entire measured quantity of photoresist from the tank and through the nozzles for application to the wafers, the high pressure on the gas being significant and substantially in excess of the small variations in pressure in the liquid photoresist at the nozzles caused by the vertical spacing of the nozzles whereby to equalize the quantity of photoresist sprayed from the several nozzles onto various silicon wafers.