3D Printing of Integrated Circuits: Four Trends You Need to Know

Is 3D printing technology ready to challenge the semiconductor chip fab market?
  • It’s been said that, to see what’s ahead for the semiconductor chip market, one simply has to look at the printed circuit board (PCB) market and think smaller. Let’s apply that reasoning to emerging additive manufacturing and 3D printing technologies for electronics.

    Today, fully functional PCBs – with integrated circuit components and other embedded semiconductor devices – can be created with 3D printers. Granted, the manufacturing is for low volume and typically low performance applications like the IoT. The most advanced 3D printing processes currently provides near micron-level resolution (around the 130um semiconductor process node equivalent) and the co-deposition of multiple materials.

    Co-deposition or multi-material deposition is critical for the 3D printing integrated circuits because conductors and semiconducting materials must be printed simultaneously. Nascent multi-material deposition technology addresses one of the major drawbacks of main existing 3D printing technologies, namely, that they only allow one material to be printed at a time. Applications like semiconductor chip fabrication require the integration of different materials at the same time.

    A recent collaborative projected between the Air Force Research Laboratory (AFRL) and American Semiconductor demonstrate the current state of the chip fabrication with 3D printing techniques. The AFRL and American Semiconductor have produced a flexible silicon-on-polymer chip with more than 7,000 times the memory capability of any current flexible integrated circuit on the market today. The manufacturing takes advantage of flexible hybrid electronics, integrating traditional manufacturing techniques with 3D electronic printing to create thin, flexible semiconductors that can augment efforts in wearable technology, asset monitoring, logistics and more. This flexible system-on-chip (SoC) is ideal for many IoT applications.

  • Other examples for the 3D printing of traditional semiconductor devices include the fabrication of certain sensors and micro-electromechanical systems (MEMs). Emerging 3D printing technologies like digital light processing (DLP) offer the high theoretical resolutions needed to compete with older (above 130 um) semiconductor process nodes. Conversely, DLP techniques do have trouble dealing with microscale voids and channels without causing clogging.

    Researches from the Singapore University of Technology and Design (SUTD), Southern University of Science and Technology (SUSTech) and Zhejiang University (ZJU), have proposed a generic process flow for guiding DLP 3D printing of miniature pneumatic actuators for soft robots with an overall size of 2-15 mm and feature size of 150-350 μm. (Note that 150 um is close to the 130 um process geometries still used in the semiconductor world for many low-cost IoT chips.) A soft debris remover with an integrated miniature gripper is used to navigate through a confined space and collection of small objects in hard-to-reach positions.

  • One area where the 3D printing of very small, chip sized devices holds promise is in the application of microfluidics. For example, Imec, a Flemish nano-electronics research hub, has developed a new impingement chip cooler that uses polymers instead of silicon, to achieve a cost-effective fabrication. Moreover, imec’s solution features nozzles of only 300µm, made by high-resolution stereolithography 3D printing. The use of 3D printing allows customization of the nozzle pattern design to match the heat map and the fabrication of internal structures. Moreover, 3D printing allows to efficiently print the whole structure in one part, reducing production cost and time.

    This technology offers a low-cost impingement-based solution for cooling chips at package level.  This achievement is an important innovation to tackle the ever-increasing cooling demands of high-performance 3D chips and systems.

  • All of these advancements are taking place near the 130um process node which is still used in the manufacture of certain semiconductor chip technologies, e.g, for the IoT.  Reaching such a low level of resolution begs the question of whether, sometime soon, an army of 3D printer might be used to product low volume and low-performance IoT integrated chips.

    A while back, I debated this question with Eric Weddington, an Open Source Architect at Trimble. He pointed out that semiconductor wafer manufacturing was a complex process consisting of many parallelized and iterative tasks. That process could not be easily accomplished by a single manufacturing machine like a 3D printer. What follows is a portion of our discussion:

    Weddington:  There are three reasons why 3D printing does not currently affect semiconductor manufacturing:

    1. There are vast differences in scale between what 3D printers do today versus semiconductor manufacturing. 3D printers cannot get down to the nanometer scale.

    2. Semiconductor manufacturing achieves efficiency partially through parallelization of the manufacturing across an entire wafer. In comparison, 3D printing is still very linear, therefore slower and less efficient.

    3. Difference in materials needed to do the manufacturing. There are some pretty harsh chemicals involved in some semi manufacturing. This is why 3D printers don’t represent any threat to semiconductor manufacturing in the near future.

    Blyler: Good points, but my premise was based on both low-cost, low-production volume lines and stereo-litho. In a manner similar to the photo-lithography used in today’s IC manufacturing, stereo-lithography – or optical fabrication – is a 3D printing technology based on ultra-violet-curable resins. Both photo- and stereo-lithography use standard patterning techniques to create a multilayered product.  I agree that 3D printers still offer little challenge to today’s semiconductor industry. But the possibility for future challenges seems quite high to me.

    Weddington: If you take a look at desktop 3D printers now, and where they have come from, they are not geared for anything like semiconductor manufacturing. The desktop 3D printers now are just an extension of commercial 3D printers, where it’s a linear process (i.e., no parallel manufacturing using masks). The new thing is basically making it low, low cost, and sitting on a desktop. But the basic tool remains the same.

    What you’re envisioning, I think (correct me if I’m wrong) is a desktop tool that is like a very low-end version of semi manufacturing tools. But these tools are inherently parallel based in what they do, and you need many different kinds of tools to make the semiconductor-wafer final output. Whereas the 3D printer, the way it works now, is the only tool for the final product.

    So while I have no problem with the vision of a low-end semi tool (or suite of them), I don’t see them as really linked to today’s desktop 3D printers. I would also add that I’m not trying to remove how revolutionary a desktop 3D printer is; I think they’re pretty cool and it adds a new dimension to all sorts of things. I just think that semiconductor manufacturing is a different beast and in a class all by itself.

    But there are ways to revolutionize that too.

    Blyler: Your comment about “needing many different kinds of tools to make the semiconductor-wafer final output” seems to be the crux of the argument. The main steps of the semiconductor manufacturing are layering, photolithography, etching, doping, resist removal, and wafer cleaning. So that’s a point well taken!

 

John Blyler is a Design News senior editor, covering the electronics and advanced manufacturing spaces. With a BS in Engineering Physics and an MS in Electrical Engineering, he has years of hardware-software-network systems experience as an editor and engineer within the advanced manufacturing, IoT and semiconductor industries. John has co-authored books related to system engineering and electronics for IEEE, Wiley, and Elsevier.

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