Dynamical method for the thermomechanical study of thin membranes

An apparatus has been built for the dynamic mechanical analysis of thin membranes, such as those of interest for x‐ray lithographic masks. Frequency and damping measurements have been made over the temperature range 100–700 K, using vibrational modes in the range 1–10 kHz. The measurements are made at pressures below 10−5 Torr to remove atmospheric loading and damping effects and thereby reveal the intrinsic membrane behavior. Stress and differential thermal expansion results are presented for B‐doped Si membranes and a PMDA/ODA polyimide membrane, prepared on Si wafers. Annealing behavior observed during thermal cycling of the Si(B) membranes has led to the discovery that the membrane stress can be varied reversibly over a wide range by the introduction and removal of hydrogen.