Charged-particle beam pattern height measurement using multi-angle scanning
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Solution Overview
Problem
Existing methods for measuring the height of patterns on semiconductor wafers, particularly those with widths of 10 nm or less, face challenges in accuracy due to the expansion of secondary electrons and variations in material and beam conditions, making it difficult to specify edge positions and achieve precise height measurements.
Innovation Solution
A method involving the acquisition of signal profiles at multiple beam incidence angles, measurement of edge dimensions, and inputting the differences into an arithmetic formula to calculate pattern height, using a charged-particle beam device and computer program for accurate height determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single beam incidence angle is used for measurement, then the measurement process is simple and fast, but the measurement precision deteriorates due to secondary electron expansion and material variations
Solution Approach 1:
The measurement process is segmented into multiple beam incidence angles (typically 0°, +45°, and -45°), where each angle provides complementary information about the pattern geometry. By dividing the measurement into angular segments, the patent eliminates the need for complex theoretical corrections while achieving high precision through simple arithmetic operations on the segmented measurements.
Solution Approach 2:
The beam incidence angle is changed across multiple discrete values to transform the measurement problem. By varying this parameter, the patent captures different projections of the pattern geometry, allowing height calculation through straightforward arithmetic without requiring complex models of secondary electron behavior or material properties.
2Measurement precision
If beam incidence angle is varied to improve edge detection, then height measurement accuracy improves, but the measurement time increases
Solution Approach 1:
The beam incidence angle is varied periodically across a small set of discrete values (0°, +45°, -45°), capturing the necessary geometric information at each step. This periodic sampling approach efficiently obtains all required measurements without unnecessary additional time consumption, as the arithmetic formula directly computes height from these periodic samples.
3Measurement precision
If conventional single-angle measurement method is used, then the device operation is simple, but the measurement precision deteriorates due to inability to correct blurring effects
Solution Approach 1:
The measurements taken at different beam incidence angles provide feedback about the pattern geometry from multiple perspectives. By combining these feedback measurements through simple arithmetic operations, the system automatically corrects for blurring and edge detection errors without requiring complex iterative algorithms or user intervention.
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 approach enables high-accuracy height measurement by stabilizing edge detection and correcting for blurring, allowing for precise process control in semiconductor manufacturing.
Implementation Method 1
the expansion of the secondary electron in the sample is changed, and a distribution of the secondary electron emitted from a side wall of the pattern is changed
Data Source
AI summary
The present invention proposes a pattern measurement tool characterized by being provided with: a charged-particle beam sub-system having a tilt deflector; and a computer sub-system which is connected to the charged-particle beam sub-system and which is for executing measurement of a pattern on the basis of a signal obtained by said charged-particle beam sub-system, wherein the charged-particle beam sub-system acquires at least two signal profiles by scanning beams having at least two incidence angles, the computer sub-system measures the dimension between one end and the other end of the pattern on the basis of the at least two signal profiles, calculates the difference between the two measurements, and calculates the height of the pattern by inputting the difference value determined by said calculation into a relational formula indicating the relation between the height of the pattern and said difference value.