In research and development, improvements are demonstrated by changing e.g. a process or materials with respect to a stable reference. The challenge is to minimize the variation of the reference process while the process itself and its environment are evolving fast to stay state-of-the art. SiCC uses lean manufacturing principles to control and predict the quality of its processing.
SMART processes and quality tests
A typical solar cell process flow involves a combination of 10 to 30 processing steps. It is essential to quickly act on the deviations of each individual step in order to minimize the number of affected experiments.
In SiCC, individual process steps are SMART defined and tested in dedicated standalone quality tests (short loop), as well as in the form of quality control measurements during regular processing. Following SPC (statistical process control) principles, all processes are controlled with respect to upper and lower control limits.
Experiment management system and planning tool
In the experiment management system (EMS) the processing runs are defined as a sequence of SMART defined process steps to be executed for multiple (experimental) splits. During operation, processes are signed off, and measurements as well as deviations are stored in the database.
The EMS system is coupled to a planning software tool that enables optimized planning, resulting in a lean flow of experiments even in the complex planning situation of an R&D lab.
Remote access allows partners to prepare and schedule their work before travelling to the laboratory, and monitor the progress of processing from a distance.
Baselines as device process flow quality tests
In order to identify deviations that are not captured by the individual process tests – such as interactions between processes- full device baselines are executed periodically, and their results are also analysed following SPC principles with control limits. More details about the baselines are described in the section ‘baselines and upgrades’