Interferometer Measurement System for Patterning Device Deformation
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Solution Overview
Problem
Current lithographic apparatuses face challenges in accurately assessing deformations of patterning devices, which can lead to mismatches and inaccuracies in pattern transfer due to mechanical stresses and thermal effects, limiting the precision of pattern alignment and focus during the manufacturing of integrated circuits.
Innovation Solution
A measurement system incorporating an interferometer system with a light source and detector, capable of emitting measurement beams to both the front and back surfaces of a patterning device, allowing for the determination of physical characteristics such as temperature or temperature offsets, which are then used to calculate deformations and adjust the pattern projection accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If IR temperature sensors are used to determine the temperature of the top surface of the patterning device, then temperature measurement is enabled, but the measurement precision of deformation assessment is insufficient
Solution Approach 1:
The patent transitions from single-point top-surface temperature measurement to multi-dimensional temperature field measurement by implementing sensors at multiple locations including the top surface, bottom surface, and interior of the patterning device. This dimensional expansion of measurement points enables comprehensive assessment of thermal gradients and their contribution to pattern deformation.
Solution Approach 2:
The patterning device is divided into multiple measurement zones with dedicated temperature sensors at each location (top surface, bottom surface, interior). This segmentation allows independent measurement of temperature at each zone, enabling the system to capture spatial temperature variations and their differential effects on pattern deformation with higher precision.
2Reliability
If only top surface temperature is measured, then measurement system complexity is reduced, but the reliability of deformation determination is insufficient
Solution Approach 1:
The temperature measurement system is designed to serve multiple functions: measuring top surface temperature, bottom surface temperature, interior temperature, and deriving thermal gradients. This multi-functionality increases reliability by providing comprehensive thermal data from which pattern deformation can be determined through established thermal-mechanical models, justifying the added sensor complexity.
Solution Approach 2:
The measurement system provides feedback by continuously monitoring temperature at multiple locations and using this data to determine pattern deformation. The deformation information can then be fed back to adjust lithographic process parameters or compensate for pattern distortion, creating a closed-loop system that enhances reliability while managing complexity through intelligent data utilization.
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 provides a more accurate assessment of patterning device deformations, enabling precise alignment and focus control, thereby improving the accuracy of pattern transfer onto substrates during lithographic processes.
Implementation Method 1
an interferometer system comprising a light source and a detector system; the light source being configured to emit, to each of a plurality of locations on the patterning device, one or more measurement beams in order to generate, at each of the respective plurality of locations, a reflected measurement beam off a front surface of the patterning device and a reflected measurement beam off a back surface of the patterning device
Data Source
AI summary
A measurement system to determine a deformation of an object having a front surface, a back surface and a pattern. The measurement system includes a processor system and an interferometer system. The interferometer system has a radiation source and a detector system. The source is configured to emit, to each of a plurality of locations on the object, measurement beams in order to generate, at each of the respective plurality of locations, reflected measurement beams off the front and back surfaces of the object respectively. The detector system is configured to receive the respective reflected measurement beams and output signals representative of the received reflected measurement beams to the processor system. The processor system is configured to receive the signals; determine, based on the signals as received, a characteristic of the object; and determine a deformation of the pattern based on the characteristic.