Wafer Alignment Model Selection for Lithography
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Solution Overview
Problem
Current lithographic processes face challenges in selecting the optimal wafer alignment model, which can introduce noise and inaccuracies in measurement operations, particularly due to the lack of external interfaces for adjusting models on a per lot or per wafer basis prior to measurement.
Innovation Solution
An apparatus and method that enable the selection and alteration of wafer alignment models using an external interface, such as the SEMI Equipment Communications Standard, based on substrate processing context information and post-exposure measurement data, to determine the best fitting model for each substrate or lot, accounting for substrate deformation and measurement target errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed wafer alignment model is used for all substrates, then the device operation is simple, but the measurement precision deteriorates due to substrate deformation variations
Solution Approach 1:
The system dynamically selects wafer alignment models based on substrate processing context information and measured substrate deformations. The model selection is not fixed but adapts to each substrate's characteristics, allowing the measurement system to optimize precision for varying substrate conditions while managing complexity through automated selection algorithms.
Solution Approach 2:
The system changes the parameters of wafer alignment models by selecting from multiple candidate models with different mathematical formulations (e.g., different order polynomials, different coordinate systems). This allows the system to match the model parameters to the actual substrate deformation characteristics, improving measurement precision without requiring manual intervention.
2Measurement precision
If multiple wafer alignment models are provided for different substrate conditions, then the measurement precision improves, but the ease of operation deteriorates due to model selection complexity
Solution Approach 1:
The system performs self-service by automatically selecting the appropriate wafer alignment model based on substrate processing context information and measured substrate deformations. The automated model selection process eliminates the need for operator intervention, maintaining ease of operation while improving measurement precision through context-aware model selection.
Solution Approach 2:
The system uses feedback from substrate processing context information and measured substrate deformations to automatically select the most appropriate wafer alignment model. This closed-loop approach ensures that the model selection is optimized for each substrate condition without requiring manual operator judgment, thereby maintaining ease of operation while improving precision.
3Manufacturing precision
If wafer alignment models are updated frequently based on substrate variations, then the manufacturing precision improves, but the loss of time increases due to model selection and updating
Solution Approach 1:
The system performs preliminary actions by pre-processing substrate information and pre-selecting appropriate wafer alignment models before actual measurement operations. This advance preparation reduces the time required during production, allowing frequent model updates based on substrate variations without significantly impacting manufacturing throughput.
Solution Approach 2:
The system efficiently processes model selection by skipping unnecessary computational steps and directly selecting from pre-evaluated candidate models based on substrate processing context information. This streamlined approach minimizes the time overhead associated with frequent model updates while maintaining high manufacturing precision.
Data Source
AI summary
An apparatus and method for performing a measurement operation on a substrate in accordance with one or more substrate alignment models. The one or more substrate alignment models are selected from a plurality of candidate substrate alignment models. The apparatus, which may be a lithographic apparatus, includes an external interface which enables selection of the substrate alignment model(s) and/or alteration of the substrate alignment model(s) prior to the measurement operation.