Reflective Substrate Edge Detection for Semiconductor Stacks
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Solution Overview
Problem
Accurately detecting the outline of a smaller upper substrate in a layered semiconductor device stack using a transmissive optical system is challenging due to the difficulty in distinguishing the edge of the upper substrate from the lower substrate.
Innovation Solution
A detection apparatus and method that employs a slit image illumination and image capturing system to identify the position of the upper substrate's edge by analyzing the step-like portion between the upper and lower substrates, utilizing a position identifying section to analyze images obtained by an image capturing section, which includes a CCD or CMOS, to accurately determine the substrate's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a transmissive optical system is used to detect the outline of substrates, then the detection process is simple and straightforward, but it becomes difficult to accurately detect the outline of the upper substrate when it is smaller than the lower substrate in a layered stack
Solution Approach 1:
The patent inverts the conventional transmissive illumination approach by using reflective illumination from the bottom side of the substrate stack. The light source illuminates the substrates from below, and the optical system captures reflected light, allowing the outline of the upper substrate to be detected against the contrasting background of the lower substrate's edge, thereby solving the detection accuracy problem while maintaining operational simplicity
Solution Approach 2:
The patent transitions from detecting substrate outlines in the planar dimension to detecting them in the vertical dimension by utilizing the height difference between stacked substrates. The optical system is positioned to capture the lateral surface of the substrates, converting a two-dimensional outline detection problem into a three-dimensional detection task that clearly distinguishes between upper and lower substrates
2Productivity
If the upper substrate is made smaller than the lower substrate to increase mount density, then the semiconductor device achieves higher integration, but the transmissive optical system can no longer accurately detect the upper substrate's outline
Solution Approach 1:
The patent inverts the illumination direction to reflective mode from below, enabling the optical system to detect the upper substrate's outline against the contrasting background created by the larger lower substrate, thus maintaining detection accuracy despite the size reduction necessary for increased mount density
Solution Approach 2:
The patent utilizes the contrast in optical properties between the upper and lower substrates created by the reflective illumination. The different heights and positions of the substrates create distinct light reflection patterns, effectively creating optical 'color' or intensity differences that enable accurate detection of the smaller upper substrate's outline
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 alignment and bonding of substrates by accurately detecting the position and outline of the upper substrate, reducing errors and improving the efficiency of substrate stacking in semiconductor device manufacturing.
Implementation Method 1
imaging at an angle with respect to the plane orientation of the lower substrate and the upper substrate, light which has been reflected by the upper surfaces of the lower substrate and the upper substrate
Data Source
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AI summary
A detection method of detecting a position of a particular one of a plurality of substrates stacked on each other, includes applying illumination to a region covering a portion of an edge of the particular substrate, obtaining an image by imaging the region, and identifying a position of the edge of the particular substrate based on a position of a step-like portion present in the image. At least one of (i) a direction in which the illumination is applied to the region in the applying and (ii) a direction in which the region is imaged in the obtaining is at angle with respect to a plane orientation of the particular substrate.