Substrate Table Overlay Determination via Temperature Data
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Solution Overview
Problem
Current methods for determining overlay in semiconductor manufacturing are inadequate, particularly in accurately assessing residual overlay errors in the first production layer without alignment marks, leading to manufacturing errors and inefficient re-working processes.
Innovation Solution
A method that determines an overlay value of a substrate by obtaining temperature data from sensors on the substrate table after loading, using this data to calculate residual overlay values, and adjusting processes such as re-working or selecting alignment models based on these values, allowing for real-time assessment and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional overlay determination methods are used, then overlay errors can be detected, but the methods are inadequate for accurately assessing residual overlay errors in the first production layer without alignment marks
Solution Approach 1:
The patent introduces temperature data as an intermediary parameter to indirectly determine overlay values. Instead of directly measuring overlay without alignment marks, the system uses temperature measurements from temperature sensors on the substrate table as a mediator to infer overlay errors. The overlay value is determined in dependence on temperature data, which reflects thermal conditions affecting substrate positioning and alignment.
2Productivity
If real-time overlay determination is implemented, then manufacturing errors can be reduced, but the complexity of the system increases
Solution Approach 1:
The system uses existing temperature sensors on the substrate table, which are already part of the lithographic apparatus infrastructure. These sensors serve dual purposes: their primary function for thermal management and their secondary function for overlay determination. By repurposing existing sensors, the system achieves real-time overlay monitoring without adding significant complexity or requiring dedicated measurement hardware.
3Measurement precision
If temperature data is used to determine overlay values, then residual overlay errors can be accurately assessed, but the relationship between temperature and overlay must be established
Solution Approach 1:
The patent changes the measurement parameter from direct geometric overlay measurement to temperature parameter measurement. By monitoring temperature data from sensors on the substrate table and determining overlay values in dependence on these temperature readings, the system transforms the measurement approach. This parameter change simplifies the measurement process while maintaining accuracy, as temperature variations correlate with thermal expansion and contraction that affect substrate alignment.
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
Enables accurate, real-time determination of residual overlay errors for the first production layer, reducing manufacturing errors and improving process efficiency by allowing for immediate adjustments and re-conditioning of substrates, thereby enhancing the overall semiconductor manufacturing process.
Implementation Method 1
obtaining temperature data that comprises data on the measured temperature at one or more positions on a substrate table after a substrate has been loaded onto the substrate table; and determining an overlay value of the substrate in dependence on the obtained temperature data
Data Source
AI summary
A method of determining an overlay value of a substrate, the method including: obtaining temperature data that includes data on measured temperature at one or more positions on a substrate table after a substrate has been loaded onto the substrate table; and determining an overlay value of the substrate in dependence on the obtained temperature data. There is further disclosed a method of determining a performance of a clamping by a substrate table using a determined overlay value.