Robson Technologies, Inc. has engineered an innovative convertible test socket that has the potential to set a new standard in modern semiconductor testing. Compared to conventional test sockets, our solution provides greater flexibility and device accessibility, with a zero working distance between the device under test and your instrumentation.
A Modular, Convertible Test Socket to Streamline Modern IC Testing
The main advantage of our Flat Top Socket Convertible (FTSC) is total unimpeded access to the device being tested, ideal for scanning WLCSP, singulated bare die and 2.5D/3D chip architectures.
Our FTSC test socket was developed for use in multiple test applications. From high-resolution subsurface scanning in verification and failure analysis to more conventional reliability, qualification, and engineering hand testing – the FTSC is truly one of the most versatile test sockets in the current market.
Test sockets follow packaging trends – new packages bring new challenges
Originally, semiconductor fabrication was a monolithic process where a single die, designed for a specific computational purpose, was responsible for containing all circuitry. High-magnification microscope inspection and device scanning needed to be performed on the top level for circuit failure.
Very Large Scale Integration (VLSI) resulted in greater densities of transistors on the die. This led to a requirement for more pathing, layers, and saw an overall increase in IC design complexity. Silicon dies were wire bonded into large scale PGA, LGA, and BGA packages, which themselves could withstand compression force enacted by the lid of the test socket while leaving a decapsulated die exposed for inspection or probing.
However, as modern semiconductors have become increasingly dense, the pathing has also become tighter, more compact and overlapping across an increasing number of layers. Modern advanced packaging techniques brought about wafer level packaging, SoC, ASIC, Multi-Chip Modules (MCM) and now 2.5D and 3D ‘chiplet’ architectures with Thru Silicon Vias (TSVs) that further restrict the accessibility of the silicon dies for optical inspection methods.
It’s clear that more precise semiconductor inspection equipment and methodologies are needed to efficiently accommodate the new, ever-evolving requirements for test socket designs. Enter Robson Technologies.
Getting Objectively Closer to Your Devices Under Test (DUTs)
Inspection methods need to keep up with the increasingly compact design of the circuits being tested in today’s semiconductor industry: tighter density, higher resolution internal structures demand a more precise way of inspecting circuits for fabrication errors and defects.
It’s often an issue of resolution: stacked chips/chiplets are becoming so compact that traditional testing apparatus and optics such as emission microscope literally cannot resolve the internal structures of singulated bare and stacked dies without assistance from something like a solid immersion lens (SIL).
Use of these lenses for inspection of singulated dies requires operation within areas typically occupied by the test socket body or compression lid. RTI’s FTSC test sockets solve this limitation by introducing the ability to add or remove the lid and floating base ‘nest’ from the equation – allowing for use with a screw-down interposer board, bringing your lens objective into direct contact with the device being tested.
Zero Working Distance Between the Tools and the Chip Die
Our convertible test socket delivers zero working distance: nothing is taller than the die itself, providing unhindered access to the entire surface. For SIL testing, you are capable of inspecting the entire die from edge-to-edge. Furthermore, requiring no intermediary quartz or sapphire cover glass when used with an interposer, the FTSC eliminates optical distortion and offers you the higher resolution scanning that today’s high density chipmaking demands.
- A test socket for all applications, providing a more simple and more streamlined testing process.
- Substantial cost savings especially for high pin count applications.
- Also allows for testing of devices in traditional floating base configuration using FA closed-top or sapphire window lids.
- The same socket is used for multiple facility locations with or without conversion kit for best quantity pricing.
More Precise IC Testing Processes in Keeping Pace with Moore’s Law
The shrinking of microchip structures has largely enabled semiconductor manufacturers to keep pace with Moore’s Law for more than half a century. In essence, manufacturers have consistently engineered ways to fit increasingly complex patterns on smaller and smaller wafers, thus doubling the number of transistors every iteration.
However, this ability to scale has begun to reach roadblocks in recent years, forcing manufacturers to innovate new chip design techniques. For example, the semiconductor industry increasingly turns to “more than Moore” IC design methods which utilize 2.5D and 3D circuit integration. The basic goal remains the same: higher density, complexity, and interconnectivity in the smallest space possible.
These innovations in microchip manufacturing require new and emerging technologies not only in the deposition and lithography processes, but also in semiconductor testing. Highly flexible, uniquely engineered testing solutions such as RTI’s convertible test socket are what will help the industry reliably continue its pursuit of Moore’s Law into the future.
