Single Sensor Substrate Alignment via Edge Profile Scanning
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Solution Overview
Problem
Conventional substrate alignment systems in semiconductor and flat panel display manufacturing are complex, costly, and prone to errors due to the need for multiple sensors and repeated substrate passing, which slows down the alignment process and is susceptible to variations in wafer edges.
Innovation Solution
A substrate processing apparatus with a single sensor capable of determining substrate alignment in two directions by generating an electronic signal from the substrate's edge profile as it intersects a linear sensor beam, allowing for real-time alignment adjustments during transit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to detect discrete edge points for substrate alignment, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The sensor beam is segmented into multiple detection zones along its length, allowing a single sensor to detect multiple discrete points on the substrate edge simultaneously. This segmentation enables the sensor to function as multiple sensors would, detecting different edge points without requiring multiple physical sensor units, thus maintaining measurement precision while reducing device complexity
Solution Approach 2:
A single sensor is designed to perform multiple functions: detecting multiple discrete edge points, determining substrate position, and measuring alignment in multiple directions. This multi-functionality eliminates the need for multiple specialized sensors, reducing both device complexity and cost while maintaining the precision required for substrate alignment
2Measurement precision
If substrate is repeatedly passed through the sensor to detect multiple edge points, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The sensor beam continuously scans across the substrate edge in a single pass, detecting multiple edge points simultaneously without requiring repeated substrate transport. This continuous detection action maintains measurement precision while eliminating the time-consuming repeated passing cycles, thereby improving productivity and alignment process speed
3Measurement precision
If discrete edge points are used for alignment detection, then measurement precision is improved, but reliability decreases due to wafer edge variations
Solution Approach 1:
The system transitions from detecting only discrete one-dimensional edge points to detecting continuous two-dimensional edge profiles across the entire substrate edge. This dimensional expansion provides redundant measurement data that compensates for local edge variations, maintaining precision while improving reliability through statistical averaging and error cancellation across multiple measurement points
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 precise and efficient substrate alignment without the need for multiple sensors, reducing alignment time and error, while maintaining high precision and speed in substrate processing.
Implementation Method 1
a sensor, connected to the control system, and having a sensor beam with a substantially linear beam cross-section, the sensor being adapted for sensing the substrate when the substrate intersects the sensor beam
Data Source
AI summary
A substrate processing apparatus has a substrate transport apparatus for transporting substrates, a sensor, and a control system. The processing apparatus is adapted to effect relative movement between the substrate and the sensor. The processing apparatus is further adapted to determine a position of the substrate by sensing the substrate with the sensor.