Strain relaxation of semiconductor membranes: insights from finite element modeling

Abstract

Finite element models were employed to better understand the process used to fabricate elastically strain-relaxed in-place bonded semiconductor membranes for application as engineered substrates for semiconductor devices [1-5]. Initial structures consist of a compressively strained, square semiconductor membrane atop a sacrificial layer that is subsequently removed by etching in an HF solution. Elastic relaxation of the compressive strain bends the free area of the membrane toward the substrate. But for the dimensions of most of the structures employed in the fabrication of in-place bonded membranes, the bending by elastic strain relaxation alone is not sufficient for the membrane corners to contact the substrate. FE models, therefore, confirm that an attractive force between the surface of the membrane and the surface of the substrate in the HF solution must act to hold the membrane in place during the wet etching process. FE models also confirm that in the etch solution the interface between the membrane and the substrate must be a sliding interface in order for the membrane to lie flat on the substrate once the sacrificial layer has been completely removed.

Deformations of Single-Crystal Silicon Circular Plate: Theory and Experiment

“…Bearing in mind the linearity of the divergence operator and taking into account the additive expansion (26), we rewrite the equation in the form div(C : ε)…”

“…It is also important to take into account the influence of tensile residual stresses that arise after performing the technological operations of the fabrication of thin-film Si membrane at different pressure and temperatures on the nature of its deflection under the impact of excess pressure. Relatively recently, a number of theoretical and experimental studies have been carried out in this direction, indicating the significant role of the initial deformation caused by a given distribution of thermal and internal mechanical stresses in the mechanical behavior of such thin-film membranes [22][23][24][25][26].…”