Pulsed Voltage Contrast Detection for Fast Charging Defects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing voltage contrast defect detection techniques in electron microscopes fail to detect high-resistance defects with time constants in the range of nanoseconds to picoseconds, and existing testing methods lack quantitative analysis of partial opens or voids in circuit components, leading to inadequate defect inspection and performance evaluation.
Innovation Solution
A charged-particle beam apparatus with a pulsed optical beam and controlled time delays between excitation and detection pulses is used to enhance voltage contrast signal, enabling detection of transient defects and providing quantitative analysis of circuit components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing voltage contrast defect detection techniques are used, then defects with time constants in the range of milliseconds to microseconds can be detected, but high-resistance defects with time constants in the range of nanoseconds to picoseconds remain undetected
Solution Approach 1:
The patent applies periodic action by using pulsed optical excitation instead of continuous illumination. The pulsed optical beam excites charge carriers in short bursts, enabling time-resolved detection of transient charging dynamics. This allows the system to capture fast transient defects with nanosecond to picosecond time constants that were previously undetectable with continuous or slow-pulsed methods.
Solution Approach 2:
The patent implements dynamics by making the detection system time-resolved and adaptable to different time constants. The system dynamically adjusts the timing of optical excitation and electron detection to match the specific time constants of different defect types. This dynamic approach enables the system to optimize detection for both fast transient defects and slower steady-state defects within the same inspection process.
2Loss of time
If existing testing techniques are used, then circuit performance information can be obtained after components are finished, but test data cannot be gathered at earlier stages when circuit components are not yet completed
Solution Approach 1:
The patent applies preliminary action by performing voltage contrast inspection during intermediate fabrication stages rather than only after completion. The pulsed optical excitation and time-resolved electron detection enable characterization of circuit components at various fabrication stages, allowing early detection of defects and performance issues before the component is fully assembled and tested.
Solution Approach 2:
The patent implements parameter changes by utilizing the time-resolved voltage contrast signal to extract multiple electrical parameters (capacitance, resistance, time constants) from the same inspection measurement. This enables comprehensive performance characterization without requiring additional tests or waiting for component completion, as the changing voltage contrast dynamics contain information about multiple electrical properties.
3Reliability
If existing voltage contrast inspection methods comparing gray levels to reference ranges are used, then full opens and leakages can be detected, but quantitative analysis of partial opens or voids cannot be provided
Solution Approach 1:
The patent introduces the time-resolved voltage contrast signal as an intermediary that carries additional information about defect characteristics. Instead of directly comparing static gray levels, the system measures the temporal evolution of voltage contrast after pulsed optical excitation. This intermediate measurement contains dynamic information that enables quantitative differentiation between various defect types (partial opens, voids, high-resistance contacts) based on their distinct charging dynamics.
Solution Approach 2:
The patent replaces the static, qualitative gray-level comparison method with a dynamic, quantitative time-resolved measurement approach. Instead of using a simple threshold-based detection system, the patent implements a time-dependent measurement system that captures the transient charging behavior. This substitution transforms the inspection from a binary defect/not-defect determination to a quantitative analysis that provides information about defect severity and type.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus improves defect detection sensitivity and throughput by detecting high-resistance defects and characterizing circuit performance with enhanced voltage contrast signals, facilitating early-stage defect identification and performance evaluation.
Implementation Method 1
an optical source configured to generate a pulsed optical beam interacting with a sample, the interaction generating a first plurality of charged particles
Data Source
AI summary
Systems and methods of observing a sample using a charged-particle beam apparatus in voltage contrast mode are disclosed. The charged-particle beam apparatus comprises a charged-particle source, an optical source, a charged-particle detector configured to detect charged particles, and a controller having circuitry configured to apply a first signal to cause the optical source to generate the optical pulse, apply a second signal to the charged-particle detector to detect the second plurality of charged particles, and adjust a time delay between the first and the second signals. In some embodiments, the controller having circuitry may be further configured to acquire a plurality of images of a structure, to determine an electrical characteristic of the structure based on the rate of gray level variation of the plurality of images of the structure, and to simulate, using a model, a physical characteristic of the structure based on the determined electrical characteristic.