Method for dispensing a layer of photoresist on a wafer without spinning the wafer

摘要

A photoresist dispensing apparatus coats a wafer with potoresist to define a layer having substantially uniform thickness. The apparatus receives photoresist into a reservoir. The photoresist flows from the reservoir to a substantially planar channel formed between parallel plates. The photoresist flows between the plates towards an elongated straight-edge exit opening. The surface tension and the viscous forces of the photoresist causes a bead to form at the exit opening. By passing a wafer beneath the dispenser apparatus at the exit opening so as to contact the bead, the surface tension is broken. As a result, the photoresist flows onto the wafer. The wafer is moved under the dispenser on tracks which maintain the wafer substantially level. The pressure from the photoresist in the reservoir maintains a steady flow of photoresist as the wafer passes below the dispenser. Accordingly, a substantially uniform layer of photoresist is applied. Photoresist layers as thin as 20 microns have been achieved. To achieve layers of one micron thickness, a wafer receiving a uniform coating as described above is spun to reduce excess photoresist. As a result, the amount of photoresist applied to a wafer to obtain a one micron layer is substantially reduced. By applying a layer having substantially uniform thickness prior to spinning, streaking and cobweb effects are eliminated.