Collapse Mechanisms for High Aspect Ratio Structures with Application to Clean Processing

Abstract

The fabrication of semiconductor devices includes the generation of high aspect ratio structures which are prone to lateral mechanical forces. Therefore, the mechanical stability of polysilicon line structures has been tested by an AFM technique for several line widths. Additionally, the damage has been evaluated and shows a uniform size distribution. These experimental results have been compared to numerical models, in which the influence of specific geometries and material present in the stack has been studied. A stress concentration region at the bottom of the line was observed and could be removed by corner rounding (fillet). Besides, the maximum stress is shifted away from the substrate. The experimental damage showed a stump at the bottom of the damage, thus confirming the numerical results.

Measurement of the mechanical stability of semiconductor line structures in drying liquids with application to pattern collapse

“…This factor can be applied to the absolute values but does not change the relative results. The absolute forces determined by the original method yield a good agreement with a finite element model presented in earlier work [19] and the literature [4]. In DI water, for example, this resulted in collapse forces of 4.2 μN with the original method [16] and 12.6 μN with the modified one [17].…”

“…the rupture occurs inside the polysilicon. Also the stress levels calculated by finite element analysis (2-3 GPa) corresponded to the reported fracture strength of polysilicon [19].…”

“…Usually, a crack initiates at a material defect or an interface in a high stress region. In this case, it could be shown that the rupture line was located inside the polysilicon and did not touch the polysilicon-SiON interface [19], i.e. the rupture occurs inside the polysilicon.…”

The Stripping Behavior of High-Dose Ion-Implanted Photoresists in Supercritical CO2Formulations

“…1,2 These physical and chemical approaches cannot only lead to the increase in material loss and surface damage but also are troublesome at present, such as chemicals and disposals cost, ultrapure water consumptions, environmental burdens, etc. 3 Furthermore, as the feature size for integrated circuits continues to shrink down, the removal of HDI PR and postetch residues in the trenches/vias with high aspect ratio structure is extremely difficult in aqueous-based cleaning solutions due to their high surface tension and capillarity. The residues at the bottom of the trenches/vias will increase the contact resistance of interconnects, which will affect the subsequent process and eventually degrade the device performance.…”

Effects of Interfacial Strength and Dimension of Structures on Physical Cleaning Window

“…The crystal mismatch and the roughness at the interface might explain the difference in pattern collapse forces. The corner rounding at the border of interface could influence the distribution of stress which could reduce the rupture at the interface [5]. However, it is difficult to control the corner rounding itself and a stronger collapse force at a smaller corner rounding as shown in Fig.…”