Laser Voltage Imaging Techniques

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Questions and Answers

What are the main techniques discussed in the paper for circuit debugging?

The main techniques discussed are Laser Voltage Imaging (LVI) and Laser Voltage Probing (LVP).

What innovative idea was introduced for TEM lamella preparation in this study?

The innovative idea introduced was the re-thinning of the lamella using the EasyLift system.

How does the EasyLift system enhance the lamella preparation process?

The EasyLift system allows operators to extract the lamella and attach it to a TEM grid within the dual beam FIB chamber.

What was the purpose of the re-thinning procedure in the context of dislocation inspection?

The purpose was to enable shallow dislocation inspection while removing deep dislocations from bulk silicon. Signup and view all the answers

What challenge is presented by the remaining shallow dislocations after the deep ones are excluded?

The challenge is that shallow dislocations, which may still pass through the channel, could be causing channel leakage. Signup and view all the answers

What type of microscopy was used in the physical failure analysis (PFA) conducted in this study?

Plan view transmission electron microscopy (TEM) was used for physical failure analysis. Signup and view all the answers

Why is it important to distinguish dislocations that induce channel leakage from those that do not?

It is important to distinguish these dislocations to prevent malfunction in electronic devices due to leakage. Signup and view all the answers

What role does the 3D-TEM play in the analysis of dislocations?

3D-TEM is used to check the depth of dislocations and exclude deep ones from further analysis. Signup and view all the answers

What is the duty cycle of the binary signal '11001100'?

The duty cycle of '11001100' is 50% in '1' and 50% in '0'. Signup and view all the answers

How does the duty cycle of '11101110' differ from '11001100'?

'11101110' has a duty cycle of 75% in '1' and 25% in '0', which is asymmetrical. Signup and view all the answers

What type of signal is generated when the duty cycle is not perfectly symmetric?

It produces a 2nd harmonic signal. Signup and view all the answers

What frequency does the LVI signal primarily detect according to the findings?

The main frequency of the LVI signal is 2.5MHz. Signup and view all the answers

What frequency should be analyzed to find the start point of a waveform change?

The 2nd harmonic LVI signal at 5MHz should be used. Signup and view all the answers

What issue was detected at cell 487 during the nano-probing?

A channel leakage was found at one device in cell 487. Signup and view all the answers

What tool was used to check the devices' behaviors in cell 487?

Nano-probing was utilized. Signup and view all the answers

What kind of curve was analyzed to investigate the leakage device?

The Id-Vg curve was analyzed. Signup and view all the answers

What was the problem when the 3D-TEM was initially executed regarding dislocations?

It only found very deep dislocations instead of the shallow dislocations needed for assessing channel leakage. Signup and view all the answers

What was suspected as the cause of the output data change in the signal transmission failure?

The hold time window variation was strongly suspected to have caused the output data change. Signup and view all the answers

Explain the significance of the hold time window in signal transmission.

The hold time window is crucial as it specifies the time data must remain stable after a clock event to ensure reliable sampling. Signup and view all the answers

During the testing, what repeating input shift pattern was used and at what clock frequency?

The input shift pattern was a repeating '11001100' at a clock frequency of 1.25MHz. Signup and view all the answers

How did the waveform change during the testing process?

The waveform changed from '11001100' to '11101110'. Signup and view all the answers

What did the circuit designer conclude about the failure mechanism based on the waveform changes?

The circuit designer concluded that the failure mechanism was strongly suspected to be due to hold time window variation. Signup and view all the answers

What was the frequency of the signal when LVI detected the second harmonic?

The frequency of the second harmonic signal detected by LVI was 5MHz. Signup and view all the answers

What remained unchanged despite the waveform alteration from '11001100' to '11101110'?

The frequency remained unchanged at 2.5MHz, despite the duty cycle differences. Signup and view all the answers

What role does the lamella play in the context of electrical fault analysis?

The lamella is used to extract and analyze specific areas of interest in bulk silicon for fault detection. Signup and view all the answers

How does Laser Voltage Imaging (LVI) aid in identifying timing failures?

LVI maps the frequency of activated transistors, allowing quick isolation of circuit defects with nanometer precision. Signup and view all the answers

Describe the function of the EasyLift NanoManipulator System in sample preparation.

The EasyLift NanoManipulator System facilitates in situ sample lift-out and enables efficient lamella extraction. Signup and view all the answers

What is the significance of the 2nd harmonic signal in the context of LVI?

The 2nd harmonic signal helps target specific devices when tracing circuit functionalities. Signup and view all the answers

What does LVP stand for, and how is it related to LVI?

LVP stands for Laser Voltage Probing and it complements LVI in detecting timing failures. Signup and view all the answers

Explain the relevance of deep dislocations in bulk silicon during failure analysis.

Deep dislocations in bulk silicon can indicate underlying issues that affect circuit performance and reliability. Signup and view all the answers

What are some characteristics of timing failures as mentioned in the text?

Timing failures occur when execution time limits, message delivery, or clock synchronization rates are not met. Signup and view all the answers

What is the role of a solid immersion lens (SIL) in this fault analysis system?

The solid immersion lens (SIL) is utilized to enhance imaging capabilities within the fault analysis process. Signup and view all the answers

Study Notes

Laser Voltage Imaging (LVI) and Probing (LVP)

LVI and LVP are laser stimulation techniques used for debugging circuits and identifying various failure modes.
Timing failures occur when execution times or clock drifts exceed predetermined limits, critical in synchronous distributed systems.

Innovative Re-Thinning Technique

A new re-thinning process in transmission electron microscopy (TEM) lamella preparation was developed using EasyLift technology.
This technique enables operators to extract lamella and attach it to a TEM grid, allowing repetitive imaging and dislocation analysis.

Dislocation Identification

Deep dislocations in bulk silicon could be identified and partially removed using the re-thinning method, helping to isolate failures related to channel leakage.
A critical observation revealed that only shallow dislocations passing through the channel could lead to leakage, as confirmed by 3D-TEM analysis.

EasyLift Nanomanipulator System

EasyLift is integrated into a dual beam focused ion beam (FIB) system and facilitates in situ sample lift-out and lamella preparation, enhancing electron microscopy capabilities.
The system was employed to perform lamella re-thinning and acquire detailed TEM images of dislocations.

Fault Detection and Analysis

Meridian WS-DP system connects to an Advantest tester, allowing live operation for electrical fault analysis through emission, LVI, and LVP.
LVI, or “frequency mapping,” aids in pinpointing activated transistors for efficient fault isolation with high spatial resolution.

Case Study of Chain Timing Failure

A specific case involving signal transmission failure was identified through LVI by analyzing waveform changes between input and output.
Duty cycle variations indicated potential hold time window issues, influencing signal integrity.

LVI Settings and Signal Analysis

Key LVI settings included utilizing a 1.25MHz clock frequency and analyzing variations in the duty cycle, which affected the harmonic signals observed.
A binary search method was employed to trace LVI signals and detect anomalies across different cells within the circuit.

Emphasis on 2nd Harmonic LVI Signal

The emergence of a 2nd harmonic (5MHz) signal was critical in detecting waveform changes reflective of deeper issues, while the main frequency (2.5MHz) focused on alterations in frequency rather than duty cycle.

Results of Fault Isolation

The analysis revealed a channel leakage in a specific device location, confirmed by nano-probing and detailed Id-Vg curve observations.
3D-TEM imaging primarily indicated deep dislocations, reinforcing the hypothesis that shallow dislocations contributed to channel leakage phenomena.

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Explore the advanced applications of 2nd harmonic laser voltage imaging in identifying timing failures and effective re-thinning techniques for dislocation identification. This quiz delves into the intricate processes and technologies used in modern semiconductor manufacturing.