No abstract

No abstract

Articles you may be interested inNanofabrication of high aspect ratio (∼50:1) sub-10 nm silicon nanowires using inductively coupled plasma etching J. Vac. Sci. Technol. B 30, 06FF02 (2012); 10.1116/1.4755835 Seasoning of plasma etching reactors: Ion energy distributions to walls and real-time and run-to-run control strategies J. Vac. Sci. Technol. A 26, 498 (2008); 10.1116/1.2909966Integrated non-S O 2 underlayer and improved line-edge-roughness dielectric etch process using 193 nm bilayer resist Appl.In this article, we have derived a run-to-run ͑R2R͒ control design technique that integrates feedforward and feedback control on the etch process. The purpose is to minimize the effect of an oxygen flow disturbance during the resist trim on the polysilicon critical dimension ͑CD͒ after the main etch. The R2R controller manipulates the resist trim time based on feedforward measurements of the resist CD at the end of the lithography and feedback measurements from polysilicon CD at the end of the etch process. The purpose of the feedforward measurement is to adjust the resist trim time using a model of the relation between trim time, resist CD before the resist trim and polysilicon CD after the main etch. The purpose of the feedback measurement is to adjust this model to compensate for the oxygen flow disturbance during the resist trim. The resulting controller is called feedforward/feedback ͑FF/FB͒ controller. The FF/FB controller is tested using simulations and experiments conducted on an etch tool manufactured by Lam Research. The simulations and experimental results show that the FF/FB controller attenuates linear drift and shift in the polysilicon CD caused by the oxygen flow disturbance. Moreover, the results quantify the significant benefit of integrating feedforward and feedback control in addition to only using a feedforward control in minimizing the polysilicon CD deviations from the etch target.

Achieving good uniformity process control in chemical mechanical polishing (CMP) requires a representative uniformity metric and strong models relating this metric to process tunable inputs. Previous efforts in CMP uniformity control have yielded acceptable results utilizing a center-to-edge (CTE) first order nonuniformity metric. Closer analysis of post CMP process nonuniformity, however, reveals significant higher order nonuniformity components such as the center “dimple” and outer “doughnut” regions. These nonuniformity characteristics are due in part to upstream chemical vapor deposition (CVD) processing. Utilizing a multizone approach to uniformity modeling, a more accurate mathematical model of CMP uniformity has been identified. The model has been utilized to customize a thickness and uniformity multivariate run-to-run software control solution for the process. The controller is based on the generic cell controller structure, which is a proven enabler for run-to-run control for a number of processes including CMP, vapor phase epitaxy, and etch. The control algorithm is a zeroth order adjustable linear approximation two-stage algorithm with exponentially weighted moving average noise filtering. This algorithm, which supports first order linear and nonlinear models, has been demonstrated to be effective in CMP CTE and thickness multivariate control. The control solution has been enhanced to utilize both pre and post CMP process metrology along with process models to suggest process recipe modifications on a run-to-run basis. Results indicate improved control of CMP process nonuniformity qualities of interest. Further, the results quantify the significant benefit of utilizing premetrology (feedforward) information in addition to traditional postmetrology (feedback) in determining control recipe advice.

No abstract