Electrical Failure Analysis of Speckled Shmoo and Shmoo Stripping failures
Electrical Failure Analysis of Speckled Shmoo and Shmoo Stripping failures
Thursday, November 20, 2025: 10:20 AM
1 (Pasadena Convention Center)
Summary:
As System-on-Chip (SoC) designs grow increasingly complex—driven by advanced clocking architectures, asynchronous independent clock domains, and continued device scaling—there has been a noticeable rise in failures that manifest as speckles or stripes in shmoo plots. This paper explores the root causes of these distinctive failure patterns and offers insights into the underlying mechanisms. We investigate a range of timing-related failure modes, including clock skew, excessive signal delays, and issues from signals crossing asynchronous clock domains. Particular focus is placed on metastability caused by inadequate glitch management. Many of these failures stem from marginalities in circuit design or manufacturing processes. The discussion begins with basic shmoo signatures linked to setup timing violations and progresses to more complex scenarios. To pinpoint the causes of speckled shmoo failures, we apply various electrical failure analysis techniques. A case study is presented involving a sub-10nm device that exhibits a speckled shmoo failure, tied to a Streaming Scan Network Transition Delay (SSN-TD) pattern, where two independent clock domains interact to produce a unique failure mode. Finally, waveform data captured using 785 nm and 1064 nm lasers is compared to highlight performance differences between the two wavelengths.
As System-on-Chip (SoC) designs grow increasingly complex—driven by advanced clocking architectures, asynchronous independent clock domains, and continued device scaling—there has been a noticeable rise in failures that manifest as speckles or stripes in shmoo plots. This paper explores the root causes of these distinctive failure patterns and offers insights into the underlying mechanisms. We investigate a range of timing-related failure modes, including clock skew, excessive signal delays, and issues from signals crossing asynchronous clock domains. Particular focus is placed on metastability caused by inadequate glitch management. Many of these failures stem from marginalities in circuit design or manufacturing processes. The discussion begins with basic shmoo signatures linked to setup timing violations and progresses to more complex scenarios. To pinpoint the causes of speckled shmoo failures, we apply various electrical failure analysis techniques. A case study is presented involving a sub-10nm device that exhibits a speckled shmoo failure, tied to a Streaming Scan Network Transition Delay (SSN-TD) pattern, where two independent clock domains interact to produce a unique failure mode. Finally, waveform data captured using 785 nm and 1064 nm lasers is compared to highlight performance differences between the two wavelengths.