Wafer alignment apparatus and method for multi-cassette load port
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor manufacturing, the alignment of wafers during transfer from a Multi-Cassette Load Port (MCLP) to a tool processing chamber is prone to misalignment, which can cause damage to the wafers.
Innovation Solution
The MCLP apparatus incorporates a wafer position sensor to measure the 3D position of wafers within the storage buffer, providing offset data to the Equipment Front End Module (EFEM) to compensate for warpage and shifting, ensuring precise alignment during transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional alignment methods are used during wafer transfer, then the alignment process is simple, but misalignment occurs causing wafer damage
Solution Approach 1:
The system performs preliminary measurement of wafer position and orientation using a sensor before the transfer operation. The measured data is used to calculate offset values that are stored and applied during the transfer, preventing misalignment before it occurs rather than correcting it during or after transfer
Solution Approach 2:
The system uses a sensor to detect the actual position and orientation of the wafer in the storage buffer, feeds this information back to the controller, which then calculates offset values to compensate for deviations from the nominal position, ensuring accurate alignment during transfer
2Manufacturing precision
If wafer position measurement is implemented, then alignment precision is improved, but the apparatus size increases
Solution Approach 1:
The sensor is positioned within the storage buffer space, utilizing the existing internal volume of the MCLP apparatus. This nesting approach allows the measurement system to be housed within the existing structure without requiring additional external space, thus improving alignment precision while maintaining a compact footprint
Data Source
AI summary
A method of a handling semiconductor wafers in a space of a semiconductor wafer processing facility includes: loading a cassette containing at least one semiconductor wafer into a storage buffer of a load port; measuring, from within the storage buffer, a position of a selected at least one semiconductor wafer being retrieve from the cassette residing in the storage buffer; and determining, at least in part based on said measuring, a variation of the position of the selected semiconductor wafer from a nominal position.