Challenges Grow For Medical ICs

Demand for medical ICs used inside and outside the body is growing rapidly, but unique manufacturing and functional requirements coupled with low volumes have turned this into a complex and extremely challenging market.

Few semiconductor applications demand this level of precision, reliability, and long-term stability. Unlike consumer electronics, where failure might mean a reboot or chip replacement, malfunctions in a pacemaker, insulin pump, or neurostimulator can have life-threatening consequences. The complexity of these devices goes well beyond just designing efficient circuits. They need to be biocompatible, resilient to sterilization processes, and function flawlessly inside the human body for more than a decade.

At the same time, medical ICs face fundamental economic hurdles. These chips typically are not sold in sufficient volume to achieve economies of scale like those found in smartphones. Medical implants often require custom, highly specialized ASICs in relatively small quantities. That means balancing advanced functionality with cost constraints to ensure access to cutting-edge semiconductor technology without the benefit of mass production.

“The biosensor/medical device space is at an exciting transformation point, with medical device designers realizing architectures mirroring those of consumer products,” says David Fromm, COO and vice president of engineering at Promex. “As recently as five years ago, most medical devices were integrations of off-the-shelf goods and functioned as standalone interactions between the device and the patient/user. Now, devices capitalize on the idea of connectivity, creating networks of patients/users, devices, secure data transmitted to the cloud, and offline analytics to improve patient outcomes.”

Meeting the strict standards for these medical devices requires specialized processes at every stage of development. On the design side, medical ICs must integrate fault-tolerant architectures, ultra-low-power operation, and secure wireless communication while ensuring compliance with strict regulatory standards. On the manufacturing side, specialized cleanroom environments, process monitoring, and extended qualification testing are needed to produce chips that can withstand biocompatibility constraints, sterilization methods, and long-term implantation without degradation. Every stage of IC fabrication, assembly, and packaging must be optimized to meet the stringent safety, reliability, and longevity requirements unique to medical applications.

“For life-critical products, customers typically implement their own qualification and screening processes to meet medical or specific end-market standards, such as FDA approval,” said a UMC spokesperson. “UMC offers a service package specifically tailored for these medical customers that ensures semiconductor ICs have a very low field failure rate, with some even achieving zero defects per million (dppm) levels.”

IC design and manufacturing
The design and manufacturing of medical ICs require a fundamentally different approach from standard semiconductor production. These chips are not just computational devices. They are life-critical components that must work flawlessly inside the human body, often in harsh biological environments with no possibility of repair or replacement.

One of the biggest constraints in implantable medical IC design is power efficiency. Unlike consumer electronics, where batteries can be recharged or replaced, implantable devices must function continuously for 10 to 20 years on a single power source. This necessitates near-threshold voltage operation, where transistors function at voltages just above their switching threshold. While that reduces power consumption and extends battery life, makers of these devices also have to manage increasing delay variability and signal integrity challenges.

Dynamic voltage scaling (DVS) and adaptive clocking are used to minimize active power consumption while maintaining processing capability. But unlike a smartphone, which can use sub-10nm process nodes to optimize performance per watt, medical ICs typically rely on mature nodes (22nm to 180nm) due to their lower leakage currents and proven long-term stability.

“Most medical ASICs are in mature nodes — 22, 40, 55 to 180nm — for cost reasons,” says Amit Gupta, product marketing director at Synopsys, noting his company provides IP at those nodes for developing these ASICs.

The choice of semiconductor materials and interconnects differs significantly from standard ICs, as well. Copper interconnects, widely used in conventional semiconductor manufacturing, are unsuitable for medical implants due to corrosion risks and potential toxicity in biological environments. Instead, medical ICs use gold (Au), platinum (Pt), and platinum-iridium (Pt-Ir) alloys for wiring and interconnects.

Gold is preferred for wire bonding, while Pt-Ir alloys are used for high-durability electrodes in neural implants and cardiac pacemakers due to their exceptional resistance to biological degradation. Tantalum (Ta) and titanium-nitride (TiN) diffusion barriers prevent metal ion leaching, ensuring the long-term stability of interconnects inside the body. In emerging flexible bioelectronics, conductive polymers and carbon nanotube interconnects are being explored to create stretchable, ultra-thin circuits that can integrate seamlessly with soft tissues.

“Material and design considerations for a medical device are often dictated by their specific product requirements,” says Promex’s Fromm. “For a biosensor with on-board chemistry, it’s common for the device to be ruined by temperatures exceeding 40°C, exposure to UV, and exposure to water. Customer processes must be developed to manage these constraints. Other classes of devices have similarly restrictive requirements that must be carefully understood before designing an assembly process.”

Ensuring fault tolerance and long-term reliability is another major challenge in medical IC manufacturing. This can include built-in self-test (BiST) mechanisms, triple modular redundancy (TMR) in critical logic paths, and error correction (ECC) in memory subsystems ensure that devices can detect and recover from faults. In some applications, radiation-hardening is used to prevent soft errors caused by cosmic rays or ionizing radiation, particularly in deep-brain stimulation (DBS) implants and long-term neuromodulation devices.

“Medical ASICs have specific requirements for safety and reliability to ensure fault-free operation for more than 10 years,” says Synopsys’ Gupta. “These include low power and low voltage to enable less frequent charging, an operating temperature range usually 0°C to 50°C, EMI (electromagnetic interference) shielding, a low form factor with specialized packaging materials, security, BLE/NFC communication to enable apps on smartphone, an analog front end, and thermal protection.”

The fabrication process for medical ICs also differs significantly from traditional semiconductor production. These chips are fabricated at specialized medical semiconductor fabs that can handle the low-volume, high-reliability production required for these devices. Wafer-level process control is far more stringent, with tight statistical process control (SPC) and in-line metrology monitoring at every stage of fabrication. In contrast to standard ICs, which are batch-tested with statistical sampling, medical ICs undergo 100% wafer-level and die-level testing before being packaged to ensure zero-defect manufacturing.

“The medical market is generally more niche compared to consumer and mobile applications,” said a UMC spokesperson. “The solutions our medical and biotechnology customers select from our foundry are diverse, encompassing logic, mixed signal, BCD, MEMS, and more. The specific solutions depend on the vertical market they are targeting and their particular areas of focus.”

Regulatory compliance adds yet another layer of complexity to medical IC manufacturing. Consumer chips can be designed, fabricated, and iterated rapidly, but medical ICs must pass rigorous regulatory approval processes before they can be implanted in patients. Standards such as ISO 13485 (Medical Device QMS), FDA 21 CFR Part 820 (Medical Device Manufacturing), and IEC 60601 (Medical Electrical Equipment Safety) dictate design controls, validation testing, and manufacturing process documentation. Any changes in the design or fabrication process — even a minor material substitution — can trigger requalification, which can significantly extend development time.

“Understanding the downstream sterilization process, if any, is critical to developing an appropriate assembly process,” says Fromm. “The type of sterilization employed has varying impact on the parts being cleaned. Autoclaving cycles are quite corrosive to exposed metals and usually require some sort of conformal coating to be applied. Typical material options compatible with autoclave are urethanes or a deposited coating like parylene.”

Challenges remain even after an IC is fully designed, fabricated, and tested. Unlike high-volume consumer semiconductor manufacturing, where yield improvements come from statistical process control and machine learning-based defect detection, medical IC production requires meticulous tracking and documentation at every stage.

Packaging challenges
Packaging of medical ICs adds still another layer of complexity. Standard semiconductor packaging is designed to protect devices from mechanical stress and environmental conditions, such as humidity or temperature fluctuations. Medical IC packaging, however, also must function as a barrier against biological fluids, resist degradation from sterilization methods, and remain completely inert inside the human body over its expected lifetime.

Materials selection is critical, with packaging solutions often incorporating hermetic seals, bio-inert coatings, and specialized polymers such as parylene or medical-grade silicones. Even small miscalculations in material stability can lead to moisture ingress, delamination, or biochemical reactions that degrade device performance.

Packaging is what ultimately determines how long a device can survive inside the human body. Unlike consumer electronics, where packaging protects against environmental stressors, medical IC packaging must withstand continuous exposure to biological fluids, extreme sterilization methods, and mechanical stresses from implantation. Materials that work well in a smartphone or a data center fail quickly inside the human body, where corrosion, moisture, and biocompatibility can sharply reduce a chip’s lifespan.

The external packaging must create a hermetic barrier against bodily fluids, which can penetrate traditional semiconductor packaging and cause gradual failure. In pacemakers, deep-brain stimulators, and cochlear implants, titanium enclosures offer a proven solution, forming an inert, corrosion-resistant shell around the IC. Titanium’s natural oxide layer makes it biocompatible, preventing immune system rejection and ensuring mechanical durability over time. In some cases, glass-to-metal sealing techniques are used to create a completely impermeable enclosure, preventing moisture ingress that could cause electrical shorts or material degradation.

“Understanding the downstream sterilization process, if any, is critical to developing an appropriate assembly process,” says Fromm. “The type of sterilization employed has varying impact on the parts being cleaned. Autoclaving cycles are quite corrosive to exposed metals and usually require some sort of conformal coating to be applied. Typical material options compatible with autoclave are urethanes or a deposited coating like parylene. At the assembly level, processes to apply these parts are often adjusted to accommodate their existence.”

Even with these well-established materials, miniaturization is driving new challenges in packaging. Many next-generation medical devices are shrinking in size, requiring more compact, flexible, and lightweight enclosures. Standard hermetic packaging techniques, while highly reliable, can be bulky and limit design flexibility. As a result, manufacturers are turning to thin-film coatings like parylene, a polymer that provides an ultra-thin, bio-inert barrier without adding significant weight or volume. Parylene is deposited using a chemical vapor deposition (CVD) process, allowing it to form a conformal, pinhole-free layer around the entire IC. This is particularly valuable for flexible biosensors and implantable monitoring devices, where rigid metal enclosures are impractical.

Sterilization resistance is another major challenge unique to medical IC packaging. Unlike consumer and industrial semiconductors, which are assembled in clean environments and then shipped for immediate use, medical ICs must be sterilized before implantation. This exposes the package to extreme conditions that can degrade materials, induce thermal expansion mismatches, or cause long-term reliability issues.

High-temperature autoclaving, for example, subjects devices to pressurized steam at 121°C or higher, which can delaminate adhesives or introduce mechanical stress on solder joints. Ethylene oxide (EtO) gas sterilization is a gentler method, but it can penetrate certain polymer coatings, altering their long-term stability. Radiation sterilization, such as gamma irradiation, presents a different set of challenges, because it can break molecular bonds in polymer-based coatings or introduce trapped charges in semiconductor dielectrics, which in turn can lead to drift in electrical characteristics over time.

“For devices that get re-sterilized multiple times, sufficient design margin should be demonstrated to buy off a material selection,” adds Fromm. “Best practices are to test to failure and ensure the appropriate survival rate beyond the desired number of cycles (with margin). Even if a design/material stack-up/assembly process gives acceptable durability and reliability, understanding and documenting the eventual failure modes is critical for managing the risks associated with a product and is a key starting point if there is an issue down the line.”

Each sterilization method dictates specific material choices and process adjustments. Devices intended for autoclaving require fully inorganic, hermetic packages with minimal polymer content, while those sterilized using EtO gas must use adhesives and coatings that are resistant to chemical diffusion. Gamma-sterilized ICs, often found in disposable biosensors, must incorporate radiation-hardened materials to prevent degradation. Because sterilization is a mandatory step in medical device manufacturing, packaging engineers must qualify every material and process step under actual sterilization conditions, adding one more layer of complexity that is not encountered in typical semiconductor packaging.

Moisture ingress is another critical failure mechanism for medical ICs, particularly for implants designed to last decades in vivo. In consumer electronics, moisture-related failures are addressed through conformal coatings and encapsulants, but these materials degrade in long-term biological exposure. Sealing out moisture often is achieved through laser-welded titanium cases, alumina ceramics, or multilayer diffusion barriers.

At the die level, manufacturers use atomic-layer deposition (ALD) techniques to create ultra-thin, pinhole-free coatings that block moisture diffusion while maintaining electrical connectivity. In emerging flexible electronics applications, such as neural interfaces and soft bioelectronics, researchers are developing multi-layer polymer encapsulation strategies that prevent water vapor penetration while maintaining mechanical flexibility.

“Medical ASICs do not need very high performance like chips in datacenters, automotive, or client devices,” says Gupta. “It’s mostly about getting good enough performance to do the job but at very low power. Both active power and leakage power reduction is important to prolong battery life, especially for SoCs that need 24-hour activity monitoring. One advantage for medical chips is the temp range is mostly 0° to 50°C, unlike -40°C to 125°C for consumer devices.”

The push toward smaller, smarter, and more connected medical devices is also driving advancements in integrated system-in-package (SiP) solutions. Traditional medical implants often consisted of discrete chips housed in separate metal enclosures, but newer designs integrate processing, sensing, and wireless communication functions into a single compact package.

This shift introduces additional packaging constraints, as multiple dies must be stacked and interconnected while still maintaining biocompatibility and long-term reliability. Manufacturers are adapting fan-out wafer-level packaging (FOWLP) and embedded die technologies —  techniques that have been widely adopted in consumer electronics but now must be optimized for the extreme durability requirements of implantable systems.

Beyond conventional implants, next-generation medical IC packaging is exploring bioresorbable materials, components designed to dissolve harmlessly inside the body after their function is complete. These devices, still in experimental stages, use magnesium-based circuits, silicon-dioxide encapsulation, and biocompatible polymer substrates that degrade over time. This eliminates the need for secondary surgeries to remove temporary implants, such as post-surgical monitoring devices or drug-delivery implants. The challenge here is balancing controlled degradation with functional stability, ensuring that the IC operates reliably for a defined period before breaking down.

Conclusion
As semiconductor packaging technology advances, medical applications are increasingly blurring the lines between electronics and biology. The demands for miniaturization, biocompatibility, hermeticity, and long-term stability are pushing innovation in materials science, encapsulation techniques, and microfabrication methods.

Unlike consumer electronics, where cost and time-to-market pressures drive decision-making, medical IC packaging is defined by one uncompromising goal — absolute reliability inside the human body. Every material, every interconnect, and every encapsulation layer must be engineered not just for performance, but for survival. In this case, it means decades of flawless operation in an environment that is inherently hostile to electronics.

Fig.1: Source: Promex Industries.

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