Semiconductor Line Inspection Using Voltage-Contrast Defect Detection
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Solution Overview
Problem
The scaling down of semiconductor devices has made it difficult to detect defects in SEM images due to their tiny size, as existing EBI methods struggle to pinpoint defects that are only a few pixels wide, leading to challenges in identifying defects between conductive lines.
Innovation Solution
An inspection method utilizing voltage contrast (VC) in SEM images, where conductive lines are pre-charged to turn on connected transistors, causing their contacts to appear bright, and defects between lines cause adjacent transistors to also turn on, making their contacts appear bright, allowing for easier detection of defects by observing the 'bright' and 'dark' states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct observation of conductive lines is used for defect detection, then the inspection method is simple, but the detection precision deteriorates due to the tiny size of defects (only a few pixels wide)
Solution Approach 1:
The patent introduces transistors as intermediary objects between the conductive lines and the detection target. By observing whether transistors connected to adjacent conductive lines turn on (indicated by bright contacts in SEM images), the system indirectly detects defects between conductive lines that are too small to observe directly. This intermediary approach transforms an impossible direct measurement into a feasible indirect detection method.
Solution Approach 2:
The patent replaces direct visual/mechanical observation of conductive lines with an electrical field-based detection method. By applying voltage to conductive lines and detecting the electrical state of connected transistors through voltage contrast in SEM images, the system substitutes direct structural observation with electrical property measurement, enabling detection of sub-pixel defects.
2Quantity of substance
If the size of semiconductor devices is scaled down, then the integration density is improved, but the defect detection capability deteriorates due to reduced defect size
Solution Approach 1:
The patent transitions from one-dimensional direct line observation to a two-dimensional detection approach by introducing transistor contacts as detection markers. The bright/dark state of contacts provides an additional dimensional signal that amplifies the detection capability, allowing defects between scaled-down conductive lines to be detected through the electrical state of associated transistors rather than direct visual inspection.
3Reliability
If conventional EBI image processing is used, then the inspection process is straightforward, but the detection reliability deteriorates for sub-pixel defects
Solution Approach 1:
The patent performs preliminary actions by pre-charging specific conductive lines before detection. This preliminary voltage application activates transistors connected to the charged lines, creating a known initial state (bright contacts) that serves as a reference. This preliminary preparation enables reliable defect detection by providing a baseline against which abnormal states (unexpectedly bright contacts on uncharged lines) can be compared.
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
This method enables clearer and more efficient detection of defects, such as short-circuits, between conductive lines by leveraging the contrast in SEM images, making it easier to identify tiny defects and reducing the need for direct observation of conductive lines, thus improving inspection accuracy and consistency with real chip structures.
Implementation Method 1
An inspection method utilizing voltage contrast (VC) in SEM images, where conductive lines are pre-charged to turn on connected transistors, causing their contacts to appear bright
Implementation Method 2
The pre-charge operation emits an electron beam toward the first conductive line contact of the semiconductor structure through the electron source
Implementation Method 3
The imaging operation scans the semiconductor structure and receiving secondary electrons that come from the semiconductor structure through the detector to generate an image
Data Source
AI summary
An inspection method for inspecting a semiconductor structure is provided. The semiconductor structure includes a first conductive line, a second conductive line, a first conductive line contact and first transistors connected to the first conductive line, and second transistors connected to the second conductive line, wherein each of the first transistors includes a first contact and each of the second transistors includes a second contact. The inspection method includes a pre-charge operation, irradiating the first conductive line contact with an electron beam; an imaging operation, obtaining an image of the semiconductor structure; and a determination operation, which determines whether the second contact of any one of the second transistors becomes bright in the image. In response to the second contact of the any one of the second transistors becoming bright, the determination operation determines that there is a defect between the first conductive line and the second conductive line.