| AVS 57th International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | B. Keville, Dublin City University, Ireland |
| Authors: | B. Keville, Dublin City University, Ireland M. Turner, Dublin City University, Ireland S. Daniels, Dublin City University, Ireland Y. Zhang, Dublin City University, Ireland A. Holohan, Dublin City University, Ireland |
| Correspondent: | Click to Email |
In general, real time, closed loop control of plasma assisted processes has not been applied in IC manufacturing. In the case of etching, 'process control' is generally understood to mean ex situ statistical analysis of metrics such as etch depth, uniformity, anisotropy and selectivity and consequent adjustment of the process recipe, which is specified in terms of inputs such as gas flow rates, forward power and pressure. An alternative approach would be to specify a recipe in terms of plasma parameters such as ion fluxes and radical densities at the wafer surface and to regulate these in real time by adjusting the inputs with a suitable control algorithm. Such an approach would mitigate potential plasma process disturbances such as wall seasoning and substrate loading, leading to an improvement in process reproducibility. This presentation describes how suitable control algorithms for low pressure plasma processes may be derived from control-oriented process models. The stability and efficacy of the control algorithms are demonstrated using an plasma simulation. Some parameters of the control algorithm depend on unknown, possibly time-varying process parameters such as wall sticking coefficients. The presentation indicates how, given a process model and process measurements, the control algorithm may be adapted/gain-scheduled in order to maintain stability. Experimental implementation of control algorithms on a capacitively coupled plasma is presented and the results are compared to those of the simulation.