CMP is a well known process in the semiconductor industry used to remove and planarize layers of material deposited on a semiconductor device to achieve a planar topography on the surface of the semiconductor device. To remove and planarize the layers of the deposited material, including dielectric and metal materials, CMP typically involves wetting a pad with a chemical slurry containing abrasive components and mechanically "buffing" the front surface of the semiconductor device against the wetted pad to remove the layers of deposited materials on the front surface of the semiconductor device and planarize the surface.
CMP has been subject to ever increasing intensive investigation and engineering with the continued focus on high speed semiconductor devices, such as those utilizing high-conductivity copper lines (interconnects). As aluminum lines and tungsten plugs are replaced with copper lines and plugs to enhance the speed of semiconductor devices by decreasing line resistance, CMP parameters utilized in connection with tungsten plugs or dielectrics may not be applicable to copper.
In addition to use of copper for metal lines in today's semiconductor devices, the line density has also been increasing. That is, today's semiconductor devices have a very high density of metal lines per unit area in a semiconductor die. Accordingly, modern semiconductor devices have relatively small line widths, and accordingly, relatively small widths associated with the dielectric material separating the lines from each other. Such fine spacing between metal lines and between areas of dielectric material presents numerous difficulties with respect to CMP of the metal, such as copper, that is deposited to form the lines. For example, very fine control of the CMP process must be executed in order to prevent undesirable erosion of the dielectric material between the metal lines, as well as undesirable dishing or dishing of the metal. Both erosion and dishing contribute to increased line resistance, and accordingly, lower speed.
Accordingly, a need exists in the art for appropriate slurry compositions for CMP of copper, as well as a process for very finely and accurately controlling CMP in critical areas such as those areas having a high density of metal lines.
USPTO Backgrounds
USPTO Backgrounds