CST Global 4” wafer bar stacker meets demand for lasers.

20 March 2017

Compound Semiconductor Technologies Global Ltd (CST Global), the UK’s leading, independent, III-V opto-electronic semiconductor foundry, has introduced a new, automatic bar stacker machine for 4” wafers.

CST Global worked with the machine manufacturer to commission, develop and optimize the new machine and processes. It accurately cleaves 4” wafers into bars, using a highly accurate, knife cutting technique. Each bar measures 250 x 100 microns and is up to 32 mm long, with around 120 lasers per bar. The bars are held in jigs of up to 80 at once, using a specially developed, non-adhesive tape. High reflectivity (HR) and anti-reflective (AR) coatings can then be applied to the front and back facet edges of the cut bars to provide enhanced laser functionality.

Ron Dickinson, Chief Operating Officer at CST Global, stated, “Laser throughput is up to 100,000 per 4” wafer and up to 200 wafers per month with the introduction and commissioning of the 4” automatic bar stacker machine. Yield is increased because the bars do not adhere to the tape, or each other, and there is less epitaxial overspill from the facet edges onto the front and back of the bars. The machine also tests the laser’s functionality whilst in bar form, before automatically separating completed bars for cutting into individual lasers.

“We are the only UK company with a 4” automatic bar stacker capability. It keeps an important part of our production capability in-house, benefiting quality control, production planning and delivery lead times. It enables us to meet the rising demand for DFB lasers for use in residential fibre-network applications.”