Discussion Overview
The discussion centers around the effects of lasers on power-off transistors, specifically whether lasers can modify the threshold voltage of these transistors. The inquiry includes considerations of different types of lasers and transistors, particularly focusing on MOSFETs in the 65 nm or 55 nm range, and seeks to establish a relationship between laser parameters and threshold voltage changes.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
- Conceptual clarification
Main Points Raised
- Some participants suggest that the effect of a laser on a transistor depends on various factors, including the type of laser (wavelength, power) and the type of transistor (individual vs. CMOS circuit).
- One participant posits that shining a high-powered laser on a transistor could decrease the threshold voltage due to heating effects, similar to using a hot-air gun.
- Another participant mentions that the effect may be related to thermal migration of the transistor's chemistry, potentially leading to accelerated aging or degradation.
- There is a request for an equation linking laser parameters to threshold voltage deviation for unpowered transistors, particularly in the context of attacks on the back side of the silicon.
- Concerns are raised about the practicality of targeting individual transistors in a 55 nm CMOS circuit due to the minimum spot size of lasers, suggesting that local heating would be the most achievable outcome.
- One participant questions whether sufficient power could permanently change transistor parameters, noting that excessive heat might destroy the circuit instead.
- Another participant clarifies that understanding the effect on a single transistor is a preliminary step before applying conclusions to larger circuits.
Areas of Agreement / Disagreement
Participants generally agree that the effects of lasers on transistors are complex and depend on multiple factors. However, there is no consensus on the specific outcomes or the feasibility of using lasers as a method to modify threshold voltages in practical scenarios.
Contextual Notes
Limitations include the dependence on specific laser parameters and transistor characteristics, as well as the unresolved nature of how these factors interact in practical applications. The discussion also highlights the challenges of targeting individual transistors within integrated circuits.