Edge Detection Device for Silicon Wafer Positioning
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Solution Overview
Problem
In silicon wafer transport systems, existing methods for position detection are inaccurate due to the reliance on friction, and integrating sensors to achieve high resolution is challenging because they must fit within a 4mm blade, leading to issues with signal smearing and inability to distinguish between position changes and reflectivity or spacing changes.
Innovation Solution
A detection method using a device with an emission region divided into subregions and a receiving region, where light is emitted and received sequentially along parallel straight lines, allowing for precise edge detection by compiling signal courses and compensating for nonlinearity through back-calculation methods, enabling integration into a blade without increasing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transmitted light method with two opposite sensor elements (transmitter and receiver) is used to achieve high measurement precision, then the measurement precision is improved, but the device complexity and constructive size increase due to requiring two separate mounting locations
Solution Approach 1:
The patent combines the transmitter and receiver into a single detection device mounted at one location. The emitter generates light that reflects off the silicon wafer surface, and the receiver detects the reflected light, merging both sensing functions into one integrated unit that can be mounted on the blade.
Solution Approach 2:
The patent transitions from a transmitted light method (requiring light to pass through space between two points) to a reflected light method where light travels in one dimension from the emitter to the wafer surface and back to the receiver, enabling single-location mounting.
2Measurement precision
If optical processing elements (lenses, prisms) are used to parallelize light beams for high resolution, then the measurement precision is improved, but the device complexity and constructive size increase due to requiring centimeter-scale propagation stretch
Solution Approach 1:
The patent extracts the light parallelization function from complex optical processing elements and achieves it through geometric arrangement of the emitter and receiver at specific angles, eliminating the need for lenses and prisms.
Solution Approach 2:
The patent replaces the mechanical/optical system of lenses and prisms with a geometric configuration system where the angular relationship between emitter, receiver, and wafer surface provides the necessary light path control without physical optical processing elements.
3Ease of manufacture
If a diffuse sensor with energetic sensor method is used for position determination, then the ease of manufacture is improved, but the measurement precision deteriorates because it cannot distinguish between position changes and reflectivity or spacing changes
Solution Approach 1:
The patent segments the emission region into multiple emission subregions along a first straight line and the reception region into multiple receiving subregions along a second straight line. By selectively activating and evaluating specific subregion pairs, the system can localize edge positions with high precision and distinguish them from other variations.
Solution Approach 2:
The patent uses the relationship between emitted and received light signals as feedback to determine edge position. By analyzing the correlation between specific emission subregion activations and corresponding receiver responses, the system can precisely identify edge locations and differentiate them from reflectivity or spacing changes.
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
This method provides accurate edge detection with high spatial resolution, suitable for silicon wafers and other objects, allowing for precise position determination within limited space, and can be adapted for various applications including web edge control.
Implementation Method 1
a light signal of light reflected on the object is received in the receiving region
Data Source
AI summary
A method for detecting an edge of an object is carried out by means of a detection device (10), which has an emission region running along a first straight line and has a receiving region which runs along a second straight line, which is arranged in parallel to the first straight line. An emission subregion (11a-p) of the emission region is selected, which extends up to a first end of the emission region. Light is emitted from the emission subregion (11a-p) and a light signal of light reflected on the object is received in the receiving region. The emission subregion (11a-p) is then shifted along the first straight line in the direction of a second end of the emission region. Emitting, receiving and shifting are repeated until the emission subregion (11a-p) extends up to the second end at the start of the shifting step. A signal course is compiled from the received light signals, and the detection of the edge from the signal course is carried out.