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Method to Eliminate Bowing Trench Profile of Structures Generated in High-Aspect Ratio Plasma Reactive Ion Etching Disclosure Number: IPCOM000013752D
Original Publication Date: 2001-Mar-01
Included in the Prior Art Database: 2003-Jun-18

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For fabrication high aspect ratio structure with small dimensions (micron, submicron, nanometers size), reactive ion etching image transfer process is normally used to form the pattern structure on photoresist, porous oxide (low k materials), polysilicon or other insulating conducting mandrel structures. During plasma RIE etching of high aspect ratio (micron, sub-micron, nanometers) structures with (RIE) image transfer process, off-angle ion and lateral radical etching of trench side wall generated bowing profile in the trench structures (1-3), especially when the (mandrel) structures are photoresist organic polymer. Due to the off-angle ion scattering profile in plasma, bowing trench normally occur in the top area (1-5 aspect ratio range of depth/opening region depending on the size of the opening and the plasma etch process). Subsequently, the structures is filled with desirable materials (metal like Copper, Aluminum for semiconductors interconnect wiring in electronic device, NiFe for pole tip in storage device, Ni or insulator as in Microelectromechanical devices) by plating, Chemical vapor deposition or spin on process to form suitable device structures. The bowing structure on top area will create difficulty in fabricating the structure without any void in the filling material. The void is generally undesirable since they tend to reduce device performance and reliability. Furthermore, it is desirable to reduce the photographic dimension of the structure of the top imaging layer by introducing this top spacer layer. The introduction of the spacer layer will eliminate bowing and reduce the photographic image structure to smaller dimension. Invention: 1) Build conventional bi-layer or tri-layer image transfer layer of desired high aspect ratio structures