A study on the stress and nonuniformity of the wafer surface for the chemical-mechanical polishing process

Abstract

In this paper, a two-dimensional axisymmetric quasic-static model for the chemical-mechanical polishing process (CMP) was established. Based on the principle of minimum total potential energy, a finite element model for CMP was thus established. In this model, the four-layer structures including the wafer carrier, the carrier film, the wafer and the pad are involved. The von Mises stress distributions on the wafer surface were analysed, and the effects of characteristics of the pad and the carrier film and the load of the carrier on the von Mises stress and nonuniformity on the wafer surface were investigated. The findings indicate that the profile of the von Mises stress distributions correlates with the removal rate profile. The elastic modulus and thickness of pad and carrier load would significantly affect the von Mises stress and nonuniformity, but those of the film did not affect very much.

The prediction of wafer surface non-uniformity using FEM and ANFIS in the chemical mechanical polishing process

“…Finally, it increases drastically and peaks significantly at the edge as shown in Fig. 6(a) and (b) [9]. This result is similar to that of [6].…”

“…Lin and Lo [9] showed that the elastic modulus and thickness of pad and carrier load would significantly affect the von Mises stress and non-uniformity on wafer surface, but those of the film did not affect a lot. Therefore, the CMP process parameters are selected by varying the carrier load in the range of 0.03448-0.10345 MPa, the pad's elastic modulus in the range of 1.1448-3.4345 MPa and the pad's thickness in the range of 0.6985-2.0955 mm.…”

“…it peaked at the edge. Lin and Lo [9] investigated further the effects of characteristics of pad and carrier film, and load of the carrier on the von Mises stress and non-uniformity on the wafer surface by using the finite element method. The findings showed that the pad's modulus of elasticity and thickness and carrier load would significantly affect the von Mises stress and nonuniformity, but those of the film did not affect them a lot.…”

Conformal polishing approach: Tool footprint analysis

“…[1][2][3][4] The CMP is based on a rotating table, a polishing head and a suspension pad, where the surface of the wafer moves across the pad, under pressure, in the presence of slurry abrasive. The mechanical movement and the downward force are applied to the wafer by the machine.…”

A hybrid model combining simulation and optimization in chemical mechanical polishing process

“…The results showed that the axial stress and strain are the dominant factors of the von Mises stress distribution on the wafer surface and the wafer deformation, and its profile is similar to Srinivasa-Murthy et al (1997), i.e., the curve peaks at the edge. Lin and Lo (2003) investigated further the effects of characteristics of the pad, carrier film, and carrier load on the von Mises stress and NU on the wafer surface by using the developed finite element model. They found that the carrier load, pad's modulus of elasticity, and thickness of pad would significantly affect the von Mises stress and NU, but those of the film did not have much effect.…”