Structuring large area WS2 layers grown by atomic layer deposition

The large-scale deposition and integration of 2D materials on 200 mm wafers for emerging microelectronic applications are highly challenging. Throughout the processing, significant issues in controlling material growth and patterning must be addressed. Therefore, this study introduces a new approach for bottom-up growth and subsequent patterning of ultrathin 2D WS<inf>2</inf> layers on 200 mm wafers. To achieve this, atomic layer deposition (ALD) was used to grow WS<inf>2</inf> thin films directly on 200 mm wafers, which were then patterned by photolithography and ion-beam etching. To prevent degradation and delamination of the WS<inf>2</inf> layer during patterning, an in situ Al<inf>2</inf>O<inf>3</inf> ALD capping layer is employed. Even after treatment in boiling de-ionized water, which porosifies the Al<inf>2</inf>O<inf>3</inf> as needed for sensing applications, the WS<inf>2</inf> and underlying features remain intact. To investigate the effects of patterning and capping processes in detail, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used. The detailed analysis shows that the proposed strategies enable patterning of WS<inf>2</inf> layers on 200 mm wafers using Al<inf>2</inf>O<inf>3</inf> capping layers. Electrical measurements of the WS<inf>2</inf> patterned on interdigitated electrodes show a linear current response and an average resistance of 0.4 ± 0.26 MΩ across the 200 mm wafer. Overall, our findings indicate a promising step toward the scalable integration of WS<inf>2</inf> into various micro- and nanosystems, especially sensors, and support future scaling of these processes.