Sputtered and anodized capacitors capable of withstanding exposure to high temperatures

Abstract

Abstract Novel structures for capacitors which are capable of withstanding heat treatments to at least 400° C. while providing low defect densities and low electrical series resistance in its electrodes are disclosed. In one embodiment of the present invention, a capacitor structure includes a bottom capacitor electrode formed of a first sub-layer of aluminum, a second sub-layer of tantalum nitride, and a third sub-layer of tantalum. The capacitor structure further includes a sputtered dielectric layer of tantalum pentoxide over the tantalum sub-layer of the bottom electrode. The resulting structure is anodized such that the underlying tantalum layer is fully anodized, and preferably such that a portion of the tantalum nitride layer is converted to a tantalum oxy-nitride. The tantalum nitride layer was discovered by the inventors to act as a good high temperature diffusion barrier for the aluminum, preventing the aluminum from migrating into the anodized tantalum pentoxide layer under high temperature processing conditions, where it would chemically reduce the tantalum atoms in the tantalum pentoxide layer and introduce conductive paths of tantalum in the dielectric (tantalum pentoxide) layer. The aluminum layer provides good electrical conductivity for the bottom electrode, and is anodized to fill any pinhole defects in the layers formed above it, thereby increasing manufacturing yields.

Inventors

• 👤 Michael G. Peters
• 👤 Michael G. Lee
• 👤 Solomon I. Beilin
• 👤 Yasuhito Takahashi

Bibliographic Details