Chartered Semiconductor Manufacturing Ltd (corporation)

Agency for Science, Technology and Research

Qiang Guo

Sang Yee Loong

Chun Hui Low

Hong Lim Lee

Bei Chao Zhang

Vladimir Bliznetsov

Xiaomei Bu

Beichao Zhang

Ahila Krishnamoorthy

An integration approach to improve electromigration resistance in a semiconductor device is described. A via hole is formed in a stack that includes an upper dielectric layer, a middle TiN ARC, and a lower first metal layer and is filled with a conformal diffusion barrier layer and a second metal layer. A key feature is that the etch process can be selected to vary the shape and location of the via bottom. A round or partially rounded bottom is formed in the first metal layer to reduce mechanical stress near the diffusion barrier layer. On the other hand, a flat bottom which stops on or in the TiN ARC is selected when exposure of the first metal layer to subsequent processing steps is a primary concern. Electromigration resistance is found to be lower than for a via structure with a flat bottom formed in a first metal layer.

Via electromigration improvement by changing the via bottom geometric profile

An improved method of forming a dual damascene structure that includes an organosilicate glass (OSG) dielectric layer is described. A via first process is followed in which a via is formed in the OSG layer and preferably stops on a SiC layer. The SiC layer is removed prior to stripping a photoresist containing the via pattern. A planarizing BARC layer is formed in the via to protect the exposed substrate from damage during trench formation. The method provides higher Kelvin via and via chain yields. Damage to the OSG layer at top corners of the via and trench is avoided. Furthermore, there is no pitting in the OSG layer at the trench bottom. Vertical sidewalls are achieved in the via and trench openings and via CD is maintained. The OSG loss during etching is minimized by removing the etch stop layer at an early stage of the dual damascene sequence.

Method to form Cu/OSG dual damascene structure for high performance and reliable interconnects

Growing community of inventors

Singapore, Singapore

Qiang Guo