The fracture characteristics of metal/polymer line structures formed by depositing Au/Cr lines on a semiflexible polyimide, pyromellitic dianhydride-oxydianiline (PMDA-ODA), substrate have been investigated using a stretch deformation technique. The delamination behavior, fracture morphology, fracture energy, and energy dissipation rate have been determined as a function of line width and thickness. The metal dimension was found to influence the crack formation mode and morphology. The experimental studies were supplemented by finite-element analysis to evaluate the stress distribution and deformation energetics of the line structure, which takes into account the plastic deformation of the metal and the polymer. Results from this analysis show that the observed fracture characteristics can be attributed to the edge and thickness effects induced by metal confinement. Essentially, the deformation behavior is determined by the mechanical environment induced by metal confinement at the interface. Plastic deformation of both metal and polymer plays an important role in controlling the stress distributions as well as the deformation energetics. The fracture energy of the metal-polyimide interface determined by an overall energy balance method was consistent with that obtained from energy dissipation rate. The average value is 25 J/m2 for the Au/Cr/PMDA-ODA line structure.

In order to maintain the dimensional accuracy of an x-ray mask, the residual stress of the absorber must be kept low (in the low range of 108 dyn/cm2 ). The absorber material studied in this paper is pure gold electroplated from a proprietary plating solution. Stress of the gold deposits is measured by holographic interferometry of bending disk/beam experiments. The effects of temperature, current density, thickness, pH, and pulse plating on the stress of the gold are investigated. The aging behavior of the plating solution is also discussed. The stress of electroplated gold does not show a strong dependence on the current density (1–5 mA/cm2 ). However, aging of the plating solution changes the stress of the gold deposits, especially for those obtained at a current density of ∼1 mA/cm2. Pulse plating produces stress levels similar to those given by dc plating, over a wide range of on-current-density, on-time, and off-time. Moreover, the pH of the solution does not affect the stress of gold when the current density is greater than 1 mA/cm2. Hence a plating solution and process has been found that produces low stress gold (≤4×108 dyn/cm2) over a wide range of operating conditions and shows no adverse effects upon aging over an extended period of time.

The fracture behavior of the Au/Cr line structures formed on a rigid-rodlike polyimide, biphenylenetetracarboxylic dianhydride-phenylenediamine (BPDA-PDA), film substrate has been investigated using a stretch deformation technique and compared with that of the Au/Cr line structures formed on a semiflexible polyimide, pyromellitic dianhydride-oxydianiline. In general, the effects of metal line dimensions on the deformation behavior can be attributed to the changes in the mechanical environment induced by metal confinement at the line interface. This gives rise to a fracture behavior and geometrical dependence of these two polyimide structures which are qualitatively similar in most aspects. However, the fracture energy and crack propagation rate of these two polyimide line structures are quantitatively different, with values about twice higher for the BPDA-PDA line structures. This cannot be accounted for solely by the different chemical bonding; instead, the high fracture toughness of the BPDA-PDA structure has to be attributed to its superior mechanical properties, particularly its plastic deformation characteristics, which are related to its molecular structure.

The fracture behavior of metal-polymer line structures as a function of dimensions was investigated using a stretch-deformation technique. The effects of line orientation, line width and film thickness are reported in this paper. When the line orientation is parallel to the stretching direction, only formation of cracks normal to the lines is observed. However, when the line is perpendicular to the stretching direction, delamination becomes the dominant mode of fracture. Wide lines (16μm) exhibit larger shear stress at the edge of the metal-polymer interface, thus delaminate earlier than narrow lines (4μm). By decreasing the metal film thickness, the depth of stress penetration at the interface decreases, making the propagation of cracks more difficult in thin films than in thick films.Finite element analysis was carried out to account for the experimental observations and good agreement was obtained. In the analysis, the plastic deformation characteristics of the metal and the polymer have been specifically taken into account. In comparison with a linear elastic analysis, the linear model predicts significantly higher stress levels and local concentrations than the nonlinear model.

The fracture behavior of the Au(Cr)/PMDA-ODA interface was investigated using a stretch deformation method. The study has been focused on thc effects of metal dimension on the delamination behavior, the fracture morphology, and energy dissipation rate of the interface. The delamination behavior shows complex geometrical dependence, with changes observed in the magnitude of strain at failure as well as the progression of the fracture process. The fracture morphology and energy dissipation rate also show apparent dependence on the metal dimensions. The crack growth, as examined by the rate of energy dissipation, seems to consist of thrce stages: crack initiation, crack growth and post growth. Only the growth region exhibits a constant dissipation rate and the fracture energy determined in this stage is in good agreement with that obtained from energy balance. These results can be attributed to the change in the mechanical coupling between the metal and the polymer layers, which was evaluated using a finite element analysis with plastic deformation taken into aiccount.