Low-K CMP process control by using interpolation method
For ILD CMP process, accurate polish time control is required to obtain expected film thickness. Comparisons between conventional SiO2 CMP process and low-k CMP process were studied and realized polishing time for low-k material can not be determined by only removal rate due to the existence of incubation time at first stage. Interpolation method was evaluated to determine polishing time for low-k CMP process. Correction of this incubation time was performed by using interpolation method and promising results were obtained.
Multiple objective APC application for an oxide CMP process in a high volume production environment
Presents three independent run-to-run APC controllers for the chemical-mechanical polishing (CMP). The controllers are applied to oxide polish processes in AMD's Fab30 to improve (a) the lot-to-lot variation, (b) to reduce the wafer-to-wafer variation and (c) to increase the wafer uniformity of the post-polish oxide thickness. Since different products and layers are processed on the same tools a method was introduced to compensate device and layer dependencies. The control algorithms were extended to a bi-layered polish process. Significant improvement was achieved for the individual controllers applied in the high volume production environment of Fab30 under the condition of a permanently changing product mix.
Multivariate run-to-run control of arm-to-arm variations in chemical mechanical planarization
With the introduction of high-throughput, multi-arm chemical-mechanical planarization (CMP) tools, a new source of process variation is introduced to the CMP process. These arm-to-arm variations are caused by small differences in the polishing rates of each arm. Modeling the arm-to-arm interactions of a CMP tool allows the application of a model-based, multi-variable, run-to-run control scheme. This control scheme is an optimization-based approach using pilot wafers applied to 'out of control' processes.In addition, this paper outlines a controller that can be applied directly to production wafers. The production-based run-to- run controller allows for monitoring the process through statistical process control methods and utilizes known relationships between product and pilot wafer removal rates in order to keep the process 'in control'. The product-based controller will be automated and deployed in AMD's Fab25- micron facility in Austin, TX using the software developed under the Advanced Control Framework Initiative.