Inverted Substrate Aligner for Fiducial Detection
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Solution Overview
Problem
Conventional substrate aligners experience inefficiencies in wafer alignment due to repeated transporter extensions and retraction, obstruction of fiducial sensors, and increased alignment times, leading to reduced throughput and potential wafer damage.
Innovation Solution
A substrate aligner apparatus featuring an inverted chuck, sensing device, and substrate transfer mechanism that allows for independent alignment and transfer of substrates without requiring transporter repositioning, enabling efficient detection and alignment of fiducials regardless of their orientation and location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate transporter extends and retracts repeatedly during alignment, then the wafer can be repositioned for alignment, but the alignment time increases substantially
Solution Approach 1:
The wafer is pre-positioned on the aligner chuck before alignment begins, eliminating the need for repeated transporter extension and retraction during the alignment process. The transporter places the wafer once, then remains retracted while the aligner performs all alignment operations independently.
Solution Approach 2:
The alignment function is separated from the transporter function. The aligner chuck and sensing devices are integrated into a独立的 alignment station that can operate without transporter intervention, dividing the overall process into independent positioning and alignment stages.
2Ease of operation
If the alignment feature is placed over the aligner rest pads, then the wafer can be positioned on the aligner, but the fiducial sensor is masked and re-tries are needed
Solution Approach 1:
The sensing devices are positioned in a different spatial dimension or location relative to the rest pads. The sensors are arranged to detect fiducials from angles or positions that are not blocked by the rest pads, allowing simultaneous wafer support and unobstructed fiducial detection.
Solution Approach 2:
The aligner chuck structure is designed to hold the wafer in a manner that does not interfere with sensor access. The rest pads support the wafer while leaving the fiducial detection path clear, acting as an intermediary that fulfills both support and non-interference requirements.
3Loss of time
If the substrate transporter remains extended during alignment, then transporter repositioning is avoided, but the aligner cannot properly detect and align the wafer fiducial
Solution Approach 1:
The wafer is pre-positioned on the aligner chuck before alignment begins, eliminating the need for repeated transporter extension and retraction during the alignment process. The transporter places the wafer once, then remains retracted while the aligner performs all alignment operations independently.
Solution Approach 2:
The alignment function is separated from the transporter function. The aligner chuck and sensing devices are integrated into a独立的 alignment station that can operate without transporter intervention, dividing the overall process into independent positioning and alignment stages.
4Manufacturing precision
If repeated wafer lifting and placing is performed, then the wafer can be repositioned for alignment, but wafer walking and backside damage increase
Solution Approach 1:
The wafer is pre-positioned on the aligner chuck before alignment begins, eliminating the need for repeated transporter extension and retraction during the alignment process. The transporter places the wafer once, then remains retracted while the aligner performs all alignment operations independently.
Data Source
AI summary
A substrate aligner providing minimal substrate transporter extend and retract motions to quickly align substrate without back side damage while increasing the throughput of substrate processing. In one embodiment, the aligner having an inverted chuck connected to a frame with a substrate transfer system capable of transferring substrate from chuck to transporter without rotationally repositioning substrate. The inverted chuck eliminates aligner obstruction of substrate fiducials and along with the transfer system, allows transporter to remain within the frame during alignment. In another embodiment, the aligner has a rotatable sensor head connected to a frame and a substrate support with transparent rest pads for supporting the substrate during alignment so transporter can remain within the frame during alignment. Substrate alignment is performed independent of fiducial placement on support pads. In other embodiments the substrate support employs a buffer system for buffering substrate inside the apparatus allowing for fast swapping of substrates.