Formation of cone shaped sapphire features has been studied using the newly developed plasma etcher PlasmaPro 1000 Astrea from Oxford Instruments Plasma Technology. This new etcher uses a large Transformer Coupled Plasma (TCP) source which generates a high ion density. Patterned sapphire etching rate up to 120nm/min could be obtained using a BCl based chemistry. Control of the process settings has allowed demonstrating cone shape features with height up to 2um, smooth sidewalls and no trenching. Uniform etching within wafer and across batches of 48 × 2" and 14 × 4" substrates has been achieved with etch rates >60nm/min and selectivity >0.7:1.
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