Batch reactive ion etching of gallium nitride using photoresist as a mask

Though advances had being made in the growth technology of gallium nitride (GaN), the device wafer sizes remain at a maximum of 2″. The consequence of this is that in a production environment single wafer processing severely impacts on throughput and therefore the profitability. Dry etching is an essential part of gallium nitride device (C.R.Eddy, Jr., Etch Process of III–V Nitrides, RES 4S1, G10.5 (1999) [1]) processing because of the high bond strength and lack of simple wet etch process. This paper discusses the methods developed to enable the Reactive Ion Etching (RIE) of batches of GaN. Photoresist was used to define mask patterns on 2″ GaN wafers. Various batch sizes were processed in an Oxford Instruments Plasma Technology Plasmalab133 RIE tool. Etch rates in excess of 50 nm/min were achieved for batches of six and fifteen two inch GaN wafers. Uniformities of etch across these batches are +/–3% and +/–5%, respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)