Spin coating apparatus having a horizontally linearly movable wafer holder

Apparatus for coating semiconductor wafers comprising:

• a first elongated member;
• a second elongated member fixed at a first end thereof to a first end of the first elongated member;
• means for rotating the first and second members about a fixed axis extending transversely to both the first and second elongated members and in proximity to the first ends of both the first and second elongated members;
• support means contained on the first elongated member for supporting a semiconductor wafer, said wafer being oriented to support a liquid on a surface thereof;
• a counterweight attached to the second elongated member;
• means for moving the support means and the wafer along a portion of the length of the first member during its rotation, while keeping the fixed axis of rotation stationary, whereby the location of the axis of rotation of the wafer relative to the location of the wafer changes during the wafer rotation, thereby to make the liquid distribution on the wafer more uniform;
• and means for moving the counterweight along a major portion of the second member during its rotation such that the distance between the center of the wafer and the fixed axis of rotation, and the distance between the fixed axis of rotation and a center of the counterweight are substantially equal.