System and method for determining film stress of multiple layers of films

Abstract

The invention discloses a system and method for determining film stress of multiple layers of films and belongs to film stress measuring technologies in the manufacturing process of integrated circuits and micro electro mechanical systems. Film material is of a multi-layer plate and shell structure for mechanics modeling so that deformation of the film material can be described with the deflection and the cross section rotation angle defined on the middle plane of the plate and shell structure, displacement or curvature torsion changes inside the middle plane and a linear or nonlinear geometrical relationship. Shape measurement equipment is adopted for measuring deformation, caused by film stress, of the film material layer by layer, a plate and shell structure finite element is adopted for dispersing the measured objects so that measuring values of all or partial finite element node freedom degrees can be given in a direct measurement or an indirect interpolation mode, the least square fit condition between deformation, at nodes, generated by film stress and measured deformation is established, and film stress of all the layers of films is reversely determined through linear or nonlinear iterative computation. Under the condition that a set temperature changes, linear or nonlinear temperature mismatch stress of the film material can be computed.

Description

technical field [0001] The invention pertains to measurement techniques used in the manufacture of integrated circuits and microelectromechanical systems (MEMS), which are used to measure thin film stress in thin film materials. Background technique [0002] Thin film materials are widely used in the manufacture of integrated circuits and microelectromechanical systems (MEMS). After chemical deposition (CVD) and physical deposition (PVD) techniques are used to form thin film materials with specific properties and functions on the surface of the substrate, the thin film materials can be processed into integrated circuits and microchips by using micromachining processes such as masks, photolithography, and corrosion. structure. Non-negligible stress inevitably occurs in the thin film material due to the crystal defects generated during the film formation process and the difference between the thermal expansion coefficients of the thin film material and the base material. Thi...

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Problems solved by technology

Although this method avoids the problem of using non-coordinated strain, it still has the following obvious defects: (1) It is generally impossible to measure the kinematic variables of all nodes, except for the nodes on the boundary, the internal nodes are not measurable , can only be obtained by interpolation; (2) It is difficult to ensure sufficient accuracy in the measurement of degrees of freedom such as rotation angles; (3) The coordination condition between the deformation of the substrate and the film is not considered; (4) The calculation needs to use the material parameters of the film; and (5) did not consider the influence of correcting external forces (such as self-weight) on the measured deformation, etc.

The second processing method avoids the above-mentioned shortcomings of the first processing method. Currently, it can handle the stress identification problem of multilayer film materials for linear and nonlinear large deflection plates, but its adaptability, flexibility and efficiency need to be further improved.

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