Key takeaways

• Chips now underpin everything from smartphones to braking systems, so failure tolerance is near zero
• Design-for-testability (DFT) shifts testing from a late-stage task to an architectural requirement
• AI-era SoCs demand hierarchical, power-aware and built-in self-test strategies to control test cost and time
• Functional verification alone is not enough: DFT is essential to catch real-world physical defects introduced in manufacturing
• The cost of robust testing is significant, but the cost for not testing is much higher
• Hierarchical DFT, including testing IP blocks, subsystems and the full SoC, is now critical to managing complexity in large designs
• Careers in DFT and chip test reward strong fundamentals, hands-on debugging and a mindset of lifelong learning and curiosity

From smartphones and smartwatches to electric vehicles and medical devices, semiconductors have become, as Vijayaprabhuvel Rajavel, Technical Architect and Engineering Program Manager at HCLTech, says: “part of everything that defines modern life.”

For Rajavel, the appeal of this field is that chips “sit at the intersection of physics, logic and creativity,” and now, reliability and design-for-testability are at the heart of semiconductor strategy.

How semiconductors became the invisible infrastructure of modern life

When asked how essential chips are today in an episode of HCLTech’s Trends and Insights podcast, Rajavel simply said: “They’re everywhere.” Phones, laptops, cars, refrigerators and wearables all “run on basically chips” that act as the brains quietly keeping everything running.

The impact runs far beyond consumer gadgets. The same silicon “can power a medical device or an EV platform or a new kind of AI model.” Remove chips from transportation, communication, healthcare or clean energy and whole systems stall. That dependence makes semiconductor reliability a business and societal concern, not just a technical metric.

Indeed, with the global semiconductor market projected to reach $1 trillion by 2030, ensuring the trustworthiness of these foundational components has never been more critical.

Chip testing: The trust layer behind reliable electronics

To manage this risk, semiconductor testing acts as the quality gate between manufacturing and the real world. “After we manufacture a batch of chips, we don’t just assume they all work perfectly,” explains Rajavel. Engineers test devices at wafer and package level, looking for physical defects that appear as electrical misbehaviour.

“In simple terms, we check that each chip does what it’s supposed to do and doesn’t have any defects.” A faulty phone processor may mean recalls and unhappy customers; a bad device in a car’s braking system or an aircraft control unit could create “a very serious safety hazard.”

Testing, he stresses, is “our way of ensuring that your devices are trustworthy…a safety net that catches the problems early.”

Design-for-Testability: Building test in from day one

Historically, testing was often bolted onto designs late in the workflow. That is no longer sustainable. Design-for-testability is “all about designing a hardware or chip with testability in mind from day one.” In practice, teams add extra circuitry purely to make the finished device observable and controllable during test.

Rajavel likens designing a complex chip to constructing a skyscraper, where DFT is “adding in multiple service elevators and inspection doors so you can easily check everything inside once it’s built.” Techniques such as scan chains and built-in self-test logic give structured access to internal nodes that cannot be reached from the outside.

Modern chips pack billions of transistors, so relying only on external pins would be “like finding a needle in a haystack.” DFT also bridges a gap with pre-silicon verification. Verification checks logical behaviour in simulation, but “verification can’t see” manufacturing defects such as broken vias, shorts or process variation: “You need some built-in hooks…after the chip is already real, not just simulated,” he says.

DFT in the AI era: Managing complexity in advanced SoCs

The rise of AI accelerators, advanced driver-assistance systems and heterogeneous SoCs has fundamentally changed how teams approach DFT. “When chips were simpler, DFT might have been a checkbox at the end,” recalls Rajavel. “Now with today’s massive system-on-chips, we have to think about testability from the very beginning,” planning DFT alongside architecture.

DFT is no longer a ‘step’ in the flow – it's part of architecture itself.

One consequence is a strong move toward hierarchical DFT. Rather than treating the SoC as a single block, engineers “break it into smaller functional blocks or IPs and give each its own test hooks, then integrate those into a top-level scheme.” This divide-and-conquer approach mirrors testing a car’s engine, brakes and electronics separately before validating the whole vehicle.

Complexity has also driven more automation and smarter tools. With millions of flip-flops, “the amount of test patterns can be huge,” so test compression and advanced automatic test pattern generation keep test time reasonable. Built-in self-test is more prominent, especially for memories and high-speed logic, because “external testing every possible scenario is very much impractical.” Teams now also consider power-aware testing and new strategies for multi-die packages to stop cost and time “spiralling out of control.”

Building a career in DFT and chip design

For engineers considering the field, Rajavel says: “Go for it. It’s a fantastic field at the intersection of hardware, software and problem solving.” His first recommendation is to “build a strong foundation” in digital logic design, circuits and programming, because those entering the field will use them all in design and test.

Hands-on experience is equally important. He suggests FPGA projects, writing simple Verilog testbenches or “just tinkering with your Raspberry Pi and sensors.”

Success in DFT also demands mindset. The industry evolves quickly, so “people who thrive here are the ones who stay curious and keep updating their skills.” The work is not always glamorous: sometimes you are “slogging through why one particular bit is flipping,” but that “attention to detail will set you apart.” Overcoming “our own fear of failure and hesitation to try new things” is key to building a long-term, rewarding career.

Testability as a strategic differentiator

As chips become more pervasive, complex and safety-critical, test engineering and DFT have shifted from niche specialisms to strategic differentiators. Organizations that design testability into architectures from day one will ship more reliable products, hit time-to-market targets and build stronger customer trust.

The next decade will push DFT into new territory – especially as new architectures, chiplets, AI driven automation, heterogenous integration redefine what is testable. The companies, and engineers, that embrace DFT and reliability as core disciplines will help define the next era of semiconductor innovation.

FAQs

1. What is Design-for-Testability (DFT) in semiconductors?
DFT is a design strategy focused on improving the testability of integrated circuits and systems. It adds dedicated on-chip structures, such as scan chains and built-in self-test logic, so internal states are controllable and observable during production test, enabling high fault coverage and reliable volume manufacturing.

2. How is DFT different from functional verification?
Verification checks design behaviour before fabrication using simulation. DFT involves designing specific circuitry pre-silicon to target physical defects that arise during manufacturing once the chip is built. Together they ensure both the intended design and the manufactured silicon are trustworthy.

3. What are the key challenges in implementing DFT for today's complex SoCs?
Modern SoCs integrate diverse components like IP blocks, memories, and even multiple dies in a single package. The main challenges involve coordinating DFT across these varied elements, managing complex hierarchical test structures, and ensuring test logic doesn't interfere with the chip's core function. Integrating third-party components and adapting to evolving industry standards are also crucial.

4. Why has chip testing become more critical in the AI era?
AI-era chips are larger, more heterogeneous and deeply embedded in safety-critical and cloud-scale systems. Testing and DFT provide the coverage, efficiency and confidence needed to ship these complex SoCs at acceptable cost and risk.

5. What skills do engineers need for a career in DFT or chip test?
Engineers need strong digital design and circuit fundamentals, at least one hardware description language, scripting for automation, and an understanding of AI/ML, plus hands-on debugging experience. Curiosity, patience and cross-functional collaboration are just as important as technical depth.

6. How can organizations start embedding testability earlier in design?
Treat test as a design constraint from architecture onwards. Involve DFT engineers early, define measurable testability goals and standardise on practices such as hierarchical DFT, built-in self-test and power-aware strategies across programmes.