Optically Tunable Soft Mask for Metrology Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical metrology techniques face challenges in accurately measuring critical dimensions and parameters of lithographic and etched features due to processing effects that degrade measurement accuracy, particularly at smaller feature sizes below the 65 nm node.
Innovation Solution
The development of optically tunable soft masks (OTSMs) with chemically amplified resist compositions that can change optical properties before and after exposure, enabling enhanced metrology measurements by creating an enhanced profile library and using a system with a lithography subsystem, metrology subsystem, and controller to compare measured data to a library, applying corrective actions as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical metrology is used to measure critical dimensions, then the measurement process is simple and fast, but the accuracy of measurements deteriorates due to processing effects on the wafer
Solution Approach 1:
The patent changes the optical parameters of the resist layer by introducing an optically tunable soft mask (OTSM) that can modify its optical properties in response to exposure conditions. This allows the resist to have different optical characteristics during lithography exposure versus during metrology measurement, thereby improving measurement accuracy without requiring complex additional measurement systems
Solution Approach 2:
The OTSM introduces dynamic optical properties to the resist layer, where the optical characteristics can change based on the process stage (lithography vs. metrology). This dynamic behavior allows the same resist layer to be optimized for both fabrication and measurement, resolving the contradiction between measurement accuracy and system complexity
2Manufacturing precision
If the resist layer has optical properties optimized for exposure, then lithography performance is improved, but metrology measurement accuracy deteriorates
Solution Approach 1:
The patent applies dynamics by making the resist layer's optical properties changeable rather than fixed. The OTSM can switch between different optical states depending on whether it is being used for lithography exposure or metrology measurement, allowing optimization for both functions without compromise
Solution Approach 2:
The patent changes the optical parameters of the resist layer by using materials that respond to exposure conditions. The OTSM modifies its optical properties (such as absorption or scattering characteristics) based on the process stage, enabling different optical optimization for lithography versus metrology
3Productivity
If feature sizes are reduced below 65 nm, then device density and performance are improved, but measurement accuracy deteriorates due to processing effects
Solution Approach 1:
The patent changes the optical parameters of the resist layer to compensate for processing effects that become more significant at smaller feature sizes. The OTSM's ability to modify its optical properties allows for enhanced measurement capability at the sub-65nm node, supporting continued device density improvement
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 improves the accuracy of critical dimension measurements and lithographic feature control by optimizing optical properties for both exposure and metrology processes, leading to more precise and reliable data for ultra-small feature sizes.
Implementation Method 1
an optically tunable soft mask (OTSM) for providing a first set of optical properties before exposure and a second set of optical properties after exposure
Implementation Method 2
The OTSM can include chemically amplified resists
Data Source
AI summary
The present invention provides methods and system for improving the accuracy of measurements made using optical metrology. The present invention relates to methods and systems for changing the optical properties of tunable resists that can be used in the production of electronic devices such as integrated circuits. Further, the invention provides methods and systems for using a modifiable resist layer that provides a first set of optical properties before exposure and a second set of optical properties after exposure.