White Paper

Advanced Endpoint Control Techniques for VCSEL Mesa Manufacture

The size of the VCSEL market is increasing and there is a pressing need to demonstrate high volume, high quality manufacturing. One of the most critical steps in manufacturing VCSEL is the formation of apertures. Aluminium rich layers are oxidised in a furnace at a high temperature under an oxygen rich atmosphere. The dry etching process of the p mesa then aims to expose the Aluminium rich layer before the oxidation.

The location of the aperture within the layer stack will depend on the design selected by VCSEL manufacturers and targeted electro-optical performance. In order to allow VCSEL suppliers to manufacture a specific design, the dry etching process must therefore be capable of stopping at any layer within the epitaxial stack. Layer by layer etching must be demonstrated across full wafers with precise control at the final layer.

Conventional time controlled etch processing is capable of supporting highly reliable manufacturing, however, endpoint techniques enable a tighter distribution of etching depth to a target layer by allowing for run-run etch variations as well as variations in the incoming material target thicknesses. Existing endpointing approaches have been tailored to meet the high volume, high yield requirements of VCSEL manufacturing.

By combining strong process expertise and deep device understanding, Oxford Instruments Plasma Technology has developed advanced plasma processing solutions to enable current and future VCSEL designs.