FormFactor

A few days ago, I went on a virtual shopping trip to Dresden, Germany, and Christmas Markets via Facetime.   I was in Dresden. My partner was on the other side of the world in Portland, Oregon, USA. From the quality of the call, we could have been in the same room. Perfect audio, perfect video, imperceptible latency. Absolutely amazing.

When I entered the semiconductor business in 1979, such a call, and many things I now use daily, were the dreams of futurists and science fiction writers. Over the next few years, we’ll continue to see the deployment of artificial intelligence, self-driving vehicles, quantum computing, and a vast array of advanced devices. Many of these new innovations will incorporate silicon photonics technologies. 

Wafer-level silicon photonics testing is a major focus area at FormFactor. Over the last eight years, we've developed and delivered many wafer-level test solutions for our silicon photonics customers, who range from Tier 1 semiconductor companies to research institutes and small startups. 

The pace of change in silicon photonics has been staggering. Over a few short years, we've gone from test setups using a pair of single cleaved optical fibers and a few analytical probes to test setups using Pharos™ optical probes with up to 64 optical fibers in a single probe used in conjunction with Apollo vertical probe cards contacting 1,000 or more solder bumps.        

Building and maintaining close working relationships with our customers has been critical to keeping pace with their needs in this rapidly evolving technology. The development of our Pharos optical probes for wafer-level testing of edge-coupled devices is a good example of working closely with our customers.   Initially, per our customer’s request, we developed a solution using tapered lensed fibers as the optical probes. At the time, the tapered lensed fiber was the best solution available. Unfortunately, the relatively large size of the tapered lensed fiber combined with the narrow width of the wafer trenches required a steep angle of incidence, resulting in large insertion losses. 

“The pace of change in silicon photonics has been Eric Christenson staggering “

FormFactor’s engineering team searched for a better solution and identified a promising 3D printing technology. After an initial internal evaluation, we partnered with a lead customer and a key supplier to develop a low insertion loss edge coupling probe. The outcome of that partnership is the Pharos ™ optical probe family and enhancements to our SiPh-Tools automation software. Edge-coupled Pharos probes have small optical periscopes and alignment fiducials printed on the polished ends of optical fibers mounted in a fiber array block. The extremely small 3D-printed optics allow the probe to be placed fully in the microscopic V-grooves or trenches at an optimal angle of incidence for coupling efficiency. To enable machine vision-based automation, a proprietary alignment fiducial is also printed on the fibers. Working with our supplier, FormFactor developed the probes and automation software with the customers supplying application requirements and test wafers. Initial testing was performed at FormFactor, followed by testing at the customer facility.

The technical and interpersonal skills of the individual engineers are critical to a successful collaboration. The engineers from the company bring unique skills and knowledge that must be combined to produce a working solution. Open-mindedness, flexibility, creativity, and a willingness to compromise are essential to producing a solution that balances the wants and needs of all three parties. My hat’s off to the individual contributors who drive these projects to success.