White Paper

High yield manufacturing of mesas in GaAs based VCSELs

The current demands from optical interconnect, LIDAR technology or face recognition is driving the VCSEL industry to grow faster. VCSEL manufacturing is rapidly scaling up across the world and the VCSEL fabrication process has to achieve ever higher yield and quality. Applications, such as 3D sensing, focus on maximum power conversion with arrays of VCSELs for higher combined output power. Within an array, the threshold current and differential quantum efficiency have to be uniform from laser to laser. This requires very good control of epitaxy but also very good control of the shape of the mesa. As the need for denser array increases, challenges on uniformity, line width and aspect ratio emerge.

With a strong process expertise and extensive device understanding, Oxford Instruments Plasma Technology has developed advanced plasma processing solutions to deliver the device performance and yield demanded by the VCSEL market.

In this white paper, we focus on how to best control the geometry of the mesa for wafer size up to 150mm. We review the key requirements for achieving either a tapered or vertical profile with precise control of the depth of the mesa.