The Perils of Aging, From a Semiconductor Device Perspective

We‘re all aware of the challenges aging brings. I find the older I get, the more in touch I feel with those challenges.  I still find it to be true that aging beats the alternative. I think most would agree. Human factors aside, I’d like to discuss the aging process as applied to the realm of semiconductor device physics. Here, as with humans, there are degradations to be reckoned with. But, unlike a lot of human aging, the forces causing the problems can be better understood and even avoided. There is a recent high-profile news story regarding issues with the 13th and 14^th generation of the Intel ‘Raptor Lake’ core processors. After a fair amount of debugging and analysis, the observed problems highlight the perils of aging from a semiconductor device perspective. Let’s look at what happened, and what it means going forward.

What Went Wrong?

Back in August, PC Magazine reported that unstable 13th and 14th Gen Intel Core processors are raising lots of concerns for desktop owners. The article went on to say that:

An unusual number of the company’s latest 14th Gen “Raptor Lake Refresh” chips, which debuted late in 2023, are proving to be prone to crashes and blue screens. Intel’s older 13th Gen “Raptor Lake” processors are, similarly, showing the same distressing traits.

What was particularly vexing was the incidence of stability issues so early in the life of these chips. And the fact that not everyone was seeing the problems, and further the problems were not always in the same form or frequency. News such as this about a part that sees widespread use can cause a lot of angst.

Root Cause Analysis

After much analysis, research and code updates, Intel has honed in the root cause and developed a plan. Dubbed the Vmin Shift Instability issue, Intel traced the problem to a clock tree circuit within the IA core which is particularly vulnerable to reliability aging under elevated voltage and temperature. What was observed was that these conditions can lead to a duty cycle shift of the clocks and observed system instability.  

Intel has identified four operating scenarios that lead to the observed issues. In a recent communication from the company, details of these four scenarios and mitigation plans were published. The company is releasing updated documentation, microcode, and BIOS to modify the clock/supply voltage behavior, so the rapid aging behavior is mitigated. Intel is working with its partners to roll out the relevant BIOS updates to the public.

This issue was manifested in the desktop version of the part. Intel also affirmed that both the Intel Core 13^thand 14^th Gen mobile processors and future client product families – including the codename Lunar Lake and Arrow Lake families – are unaffected by the Vmin Shift Instability issue.

These fixes are taking a substantial amount of resources, both to mitigate the problem and deal with the impact in the market.

How to Avoid Problems Like This

This is a highly visible example of what happens when clock trees go out of specification particularly when N- and P-channel devices age differently, leading to asymmetrical changes in clock signals. As these performance shifts accumulate, circuits stop working reliably or stop working completely.

The solution to such aging degradation lies in the use of precise, high-resolution analysis tools throughout the design process.  It turns out there is a company that targets the identification and mitigation of clock anomalies. Infinisim solution ClockEdge® offers a powerful approach, simulating how clock signals degrade over time due to factors like Negative Bias Temperature Instability (NBTI) and Hot Carrier Injection (HCI). By performing comprehensive aging simulations across entire clock domains over multiple PVT corners, Infinisim’s technology allows designers to predict signal degradation and mitigate its impact, effectively extending the operational lifespan of high-performance clocks.

My gut tells me Intel’s problems could have been tamed before they reached the field with tools like this. By identifying potential clock aging failures early, Infinisim’s solutions reduce the risk of expensive field failures and costly silicon re-spins. Their proven track record demonstrates how they enable customers to achieve exceptional design robustness before tape-out, providing fast, accurate analysis that helps optimize performance without compromising reliability.

You can learn more about clock aging and Infinisim’s approach in this blog on SemiWiki. And that’s a look at the perils of aging from a semiconductor device perspective.