Diffraction Pattern Filter for Nanoscale Semiconductor Measurement
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Solution Overview
Problem
Existing optical measurement tools for semiconductor devices face interference from diffraction patterns generated by underlying CMOS-under-array structures, which complicates the measurement of nanoscale dimensions in three-dimensional memory devices, leading to inaccurate results due to noise from background device structures.
Innovation Solution
A diffraction pattern filter is introduced within the detection assembly of the measurement apparatus, configured to permit light diffracted by the periodic structure of interest while blocking light diffracted by other structures, using a customized pattern of opaque material on a transparent substrate to filter out interference patterns, allowing for precise measurement of nanoscale dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical measurement is performed on three-dimensional memory devices with CMOS-under-array structures, then measurement capability is provided, but measurement accuracy deteriorates due to interference from background diffraction patterns
Solution Approach 1:
The patent extracts and removes the harmful background diffraction patterns from the detection path using a filter. The filter is configured to block diffraction patterns originating from CMOS-under-array structures while allowing diffraction patterns from the memory device structures to pass through to the detector, thereby separating the useful signal from the harmful interference.
Solution Approach 2:
The patent introduces a filter as an intermediary component between the semiconductor device and the detector. This filter acts as a mediator that selectively transmits or blocks specific diffraction patterns based on their spatial characteristics, enabling the detector to receive only the relevant diffraction information while filtering out interference from background structures.
2Measurement precision
If a diffraction pattern filter is added to block interference, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The filter serves multiple functions simultaneously: it blocks harmful diffraction patterns from CMOS-under-array structures, transmits useful diffraction patterns from memory device structures, and maintains the overall optical path functionality. This multi-functionality justifies the addition of the filter component by providing comprehensive interference rejection in a single element.
3Loss of information
If diffraction patterns from all structures are detected, then comprehensive information is obtained, but signal-to-noise ratio deteriorates due to unwanted background patterns
Solution Approach 1:
The filter is designed with spatially varying transmission properties that correspond to the specific locations of harmful diffraction patterns in the diffraction space. Different regions of the filter have different optical densities tailored to block specific background diffraction patterns while preserving the diffraction patterns from the structures of interest, thereby maintaining information completeness while removing noise.
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 diffraction pattern filter effectively suppresses noise from background device structures, enabling accurate measurement of nanoscale dimensions in semiconductor devices by isolating the diffraction pattern of the target structure, thereby improving the precision and reliability of optical dimension measurements.
Implementation Method 1
light diffracted by the periodic structure to be measured and block at least a portion of light diffracted by other structures
Implementation Method 2
a diffraction pattern filter configured to permit light diffracted by the periodic structure to be measured to reach the detector and block at least a portion of light diffracted by other structures
Data Source
AI summary
A measurement apparatus for measuring dimensions within a semiconductor device includes an illumination source configured to direct light onto a stage configured to hold the semiconductor device, and a detection assembly configured to receive light diffracted by the semiconductor device, in which the detection assembly includes a detector configured to receive light diffracted by the semiconductor device and determine a measurement of a periodic structure within the semiconductor device based on the received diffracted light, and a diffraction pattern filter configured to permit light diffracted by the periodic structure to be measured to reach the detector and block at least a portion of light diffracted by other structures in the semiconductor device from reaching the detector. Embodiments include methods of measuring a semiconductor device using the measurement apparatus and methods of making the diffraction pattern filter.