Automation is endemic in today’s economy, and additive manufacturing is just one of many technologies that are infiltrating manufacturing facilities in all industries. Additive manufacturing systems are saving costs and unleashing design freedom for a broad range of products. These products tend to have lower weight and less complexity, the fabrication processes waste less material, and the overall manufacturing costs for many products are reduced as a result.
As the range of materials available for use in additive manufacturing systems, as well as the diversity of systems themselves, continue to expand, unique semiconductor devices that include exotic materials and unique architecture will become incorporated into 3D-printed electronics. Additive manufacturing for semiconductor devices provides many of the benefits found in other products, and these devices can be incorporated into 3D-printed PCBs and other electronics.
A process engineer holding a finished semiconductor wafer.
Current Challenges in the Semiconductor Industry
Semiconductor devices encompass more than just computer chips. LEDs, nonlinear passive components like diodes, transistors, sensors, and other electronic devices are made from a variety of semiconductors. Anyone familiar with Moore’s Law knows that continued miniaturization has been the primary focus in the semiconductor industry for the last 50+ years, but major manufacturers are struggling to break past the physical limitations in semiconductor devices.
To overcome some basic phenomena in quantum physics, current research in this area has focused on designing new device architecture to continue miniaturization and increase component density.
A prime example from the semiconductor industry is the use of Fin-FETs, which is now the standard architecture in computer processors. This unique gate architecture provides lower power consumption, high ON-OFF current ratio, and better control over tunneling current in these devices.
In solid-state semiconductor devices, the architecture in experimental tunnel FETs takes advantage of quantum tunneling in III-V materials, Ge, non-stoichiometric InGaAs, and Si to provide extremely high ON-OFF current ratios.
Organic and Inorganic Polymers
Other avenues of research have focused on the use of organic and inorganic polymers to continue miniaturization and fabricate semiconductor devices with unique functionality. Polymers can be doped with a wide variety of low-temperature processes, making them ideal for use in unique devices, such as fully flexible electronics. The use of functionalized polymers and doping in polymers also allows materials and systems designers to tune the material properties of these devices to meet specific design goals.
This is where additive manufacturing can play a major role in the near future, both in research on new devices and in mass manufacturing of semiconductor devices. Polymers are naturally adaptable for use in additive manufacturing systems because they can be used in low-temperature, low-pressure fabrication processes, like inkjet printing, aerosol printing, screen printing, and similar processes. With the right additive manufacturing system and process, polymer materials can be co-deposited alongside nanoparticle materials to form insulating and conductive elements simultaneously in a single fabrication run.
Additive Manufacturing for Semiconductor Devices with Polymers
Polymers come in the conductive and insulating variety, and co-deposition of these two types of polymers allows an insulating dielectric and conductive elements to be printed with a low-temperature process. The semiconducting material tends to be a native p or n-type polymer that can be printed at a low temperature. Doped polymers can also be used in semiconductor devices, although doping processes for some polymers can involve some noxious chemicals and can carry increased material costs.
The use of polymers in additive manufacturing for semiconductors allows some fundamental devices to be printed, either alongside a substrate or directly on top of a substrate.
The example below shows the architecture in a 3D-printed organic thin-film transistor. Using a high-k polymer between the conductors and the polymer materials allows the gate to be made thicker, which suppresses leakage current and allows further scaling to smaller devices. Similar architecture with two electrodes could be used with electroluminescent polymers to fabricate LEDs, or with native or doped p and n-type polymers to fabricate diodes.
Organic thin-film transistor architecture
One should note here that the printing process involved in fabricating this structure and a similar structure requires co-deposition of the conductive electrodes (source, gate, and drain), and the insulating (dielectric) and semiconducting polymers. This is where inkjet printing is advantageous because it is ideal for depositing multiple materials simultaneously. Other processes could be adapted to deposit these structures and similar devices.
When combined with different processes for 3D printing PCBs, inkjet printing and similar additive processes allow these unique semiconductor devices to be printed alongside novel 3D-printed electronic components, such as unique antennas and RF devices, sensors, and embedded passive components. When incorporated within a traditional electronics assembly process, 3D-printed PCBs with printed semiconductor devices can interface with standard surface-mount or through-hole components.
Printed Semiconductor Devices in Additively Manufactured PCBs
Traditional manufacturing processes limit designers in terms of interconnect architecture, planarity, and substrate shape. In contrast, additively manufactured PCBs are not limited by subtractive manufacturing constraints, saving companies time and money, as well as providing designers greater freedom to design PCBs with complex architecture and customize designs as needed.
Working with an additive manufacturing system that is designed for 3D printing PCBs is an excellent way to complement an existing manufacturing process for low-volume, high-complexity PCBs. The layer-by-layer printing process in 3D printing allows low-volume manufacturing runs of PCBs with any level of complexity, including non-planar PCBs and high-value boards with very complex shapes. Working with a 3D printing process, like inkjet printing, allows multilayer PCBs with complex geometry to be 3D printed in a single run as the dielectric substrate and conductive nanoparticle ink can be co-deposited during printing.
These boards can then be sent along through a traditional assembly process, allowing passive and active semiconductor devices to be soldered on a 3D-printed PCB with standard processes. When active and passive semiconductor devices can also be 3D printed, this eliminates assembly and soldering steps, as semiconductor devices can be fabricated directly on a 3D-printed PCB. This facilitates greater integration of semiconductor devices directly onto PCBs, increases throughput, and reduces material waste. Furthermore, assembly time can be reduced if multiple parts are redesigned into single pieces.
Additive manufacturing for semiconductor devices with novel architecture and materials is likely to become mainstream sooner than we think. You can complement other additive processes for semiconductor devices with an inkjet additive manufacturing system that can expedite prototyping and complete fabrication of complex 3D-printed electronics. The DragonFly LDM is a unique inkjet system that allows semiconductor devices to be integrated into planar and non-planar 3D-printed electronics. Read a case study or contact us today to learn more about DragonFly LDM.