X-ray mask membrane deflection compensator and method

Abstract

An x-ray mask membrane reflection compensator includes an x-ray chamber having a transmitting gaseous media therein chamber through which x-rays are directed to a mask membrane that is positioned in close spaced proximity to a resist-coated wafer. A controlled environment of processing gas is provided within a gap between the mask membrane and wafer surfaces. The processing gas and gaseous media pressures variously cause bulging of the membrane resulting in a descrepancy in the gap distance across the field of view. A laser source provides an incident beam of light which is directed at an incident angle to the mask membrane and the wafer surface such that return beams are reflected and interference fringe patterns, due to slight nonparallelism of the mask membrane and the wafer are displayed on a monitor. A standard reference line is established by a reference fringe band at a null position of the mask membrane and the movement of the reference fringe based from the references line is utilized to detect the deflection of the mask membrane by reason of a net differential pressure on the mask membrane. Control of the pressure of the processing gas or chamber gaseous media returns the reference fringe band pressure to the reference line to indicate that the mask membrane is back at a null, nondeflected position.