Phase Shift Measurement Using Integrated Reticle Inspection
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Solution Overview
Problem
Current methods for measuring semiconductor reticles, particularly phase and amplitude of light transmitted through them, are inadequate for precise yield improvement due to sensitivity to structure and process variations in large-scale circuit integration and decreasing device sizes.
Innovation Solution
A method and system using specialized phase-shift targets and a mask inspection tool to determine phase shift values by directing an incident beam towards the targets and measuring intensity values, which are then used to calculate phase shift, incorporating features like phase-shifting layers, gratings, and reflective or refractive optics for accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate interferometer tools are used to measure phase shift, then measurement precision is improved, but device complexity and contamination risk increase
Solution Approach 1:
The patent combines the phase shift measurement capability with the existing reticle inspection tool, eliminating the need for separate interferometer tools. The inspection tool is modified to include phase detection functionality, merging two previously separate functions into one integrated system, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The inspection tool is designed to perform multiple functions: both standard reticle inspection and phase shift measurement. By making the inspection tool universal, the system eliminates the need for specialized interferometer equipment, reducing overall system complexity while preserving the ability to perform precise phase measurements
2Measurement precision
If separate interferometer tools are used to measure phase shift, then measurement precision is improved, but contamination during inspection increases
Solution Approach 1:
By merging phase shift measurement and reticle inspection into a single integrated tool, the reticle remains stationary and is inspected in-situ without being transferred to separate equipment. This eliminates contamination risks associated with moving the reticle between different tools while maintaining measurement precision
3Measurement precision
If multiple separate tools are used for reticle inspection and phase measurement, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent integrates phase shift measurement and amplitude measurement capabilities into the existing reticle inspection tool, allowing all measurements to be performed in a single workflow. This eliminates the need for sequential use of multiple separate tools, significantly improving productivity while maintaining measurement precision
Solution Approach 2:
The inspection tool is designed to perform multiple measurement functions (phase shift, amplitude, and standard inspection) in one integrated system, enabling comprehensive reticle characterization without requiring multiple separate tools, thereby improving inspection efficiency and productivity
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 allows for precise determination of phase shift values, enhancing yield by reducing the need for separate interferometer tools and minimizing contamination during the inspection process, thus improving the accuracy and efficiency of semiconductor reticle measurement.
Implementation Method 1
direct an incident beam towards the target and then detect a plurality of intensity measurements that are transmitted through the target in response to the incident beam
Implementation Method 2
a first portion formed from a phase-shifting layer deposited over a substrate
Implementation Method 3
a third portion comprised of one or more gratings etched in the phase-shifting layer and the intensity measurements are also obtained for each imaged diffraction order
Implementation Method 4
the objective is a reflective or refractive element
Implementation Method 5
the measured intensity values are obtained from a pupil image using a Bertrand lens
Implementation Method 6
a plurality of reflected intensity values that are reflected from the target in response to the incident beam are measured
Data Source
AI summary
In one embodiment, disclosed are apparatus, methods, and targets for determining a phase shift of a photomask having a phase-shift target. An inspection or metrology system is used to direct an incident beam towards the target and then detect a plurality of intensity measurements that are transmitted through the target in response to the incident beam. A phase shift value for the target may then be determined based on the intensity measurements.