Stress analysis in Si membranes for open stencil masks and mini-reticles using double bulging and resonance methods

This paper presents two measurement methods for stress determination of Si- membranes. The first one is based on the bulging method. This method was mo dified by the deflecting of the membrane in both direction, the so-called d ouble bulging technique. A novel improved least-square fitting technique to double bulging data allows to increase the accuracy of the method especial ly for the membranes with stresses lower than 2 MPa. Additionally it is pos sible to verify the set up alignment for the diffraction-image method. This method we have used for measurement of membrane deflection. The second met hod - resonance frequency method - is based on the classical theory of memb rane vibration. It uses the dependency of the membrane resonance frequency on membrane residual stress. This novel technique applies a soft piezoresis tive cantilever in contact mode for the detection of membrane vibration. Th e influence of the cantilever on the vibration of the membrane was studied. Initial results show the small lowering of the resonance frequency in meas urements with the cantilever in comparison with the optical measurements. ( C) 2001 Elsevier Science BY All rights reserved.