Alignment Mark Brightness Contrast for Semiconductor Chip Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor devices using the Chip-on-Glass method, the miniaturization of IC chips leads to reduced reflectivity of aluminum alignment marks due to antireflection films and surface irregularities, making it difficult to achieve high contrast and accurate alignment detection.
Innovation Solution
The alignment mark is designed with a bright area reflecting light from the semiconductor substrate's smooth surface and a dark area with metal wirings that scatter light, enhancing the contrast ratio for accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an aluminum layer is used to form the alignment mark, then the alignment mark can be formed simultaneously with the wiring layer, but the reflectivity of the aluminum layer is reduced due to antireflection films and surface irregularities, making it difficult to achieve high contrast
Solution Approach 1:
The patent applies local quality by creating distinct regions with different optical properties: a bright area with high reflectivity (using transparent resin or glass substrate) and a dark area with low reflectivity (using metal wiring). This local differentiation of material properties enables high contrast detection while using the existing aluminum wiring layer formed during normal manufacturing processes.
Solution Approach 2:
The patent utilizes optical property changes by designing the alignment mark to exhibit contrasting brightness levels. The bright area reflects light strongly while the dark area absorbs or scatters light, creating a visible contrast that enables accurate detection. This approach transforms the alignment mark from a uniform structure to one with differentiated optical characteristics.
2Productivity
If the IC chip is miniaturized, then circuit integration is improved, but the interval between pads becomes narrower, causing misalignment and connection errors
Solution Approach 1:
The patent introduces an intermediary detection system using a photo detector to detect the alignment mark. This intermediary device mediates between the miniaturized IC chip structure and the alignment process, enabling precise detection of the alignment mark position even when pad intervals are narrow, thereby maintaining alignment accuracy despite circuit miniaturization.
Solution Approach 2:
The patent replaces mechanical alignment methods with an optical detection system. Instead of relying on mechanical positioning, the system uses light reflection and photo detector detection to identify the alignment mark position, enabling more precise alignment control for miniaturized devices where mechanical tolerances become insufficient.
3Measurement precision
If a photo detector is used to detect the alignment mark, then alignment accuracy can be improved, but the alignment mark must be easily recognizable through the transparent substrate
Solution Approach 1:
The patent applies universality by making the alignment mark structure serve multiple functions: it provides both the electrical wiring function (through the metal wiring layer) and the alignment detection function (through the contrast pattern). The same metal wiring layer that conducts electricity also creates the dark area of the alignment mark, eliminating the need for separate alignment mark structures and simplifying the overall device complexity.
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 design improves the contrast ratio between the bright and dark areas, allowing for precise alignment of IC chips on transparent substrates, even in miniaturized semiconductor devices, without increasing manufacturing steps.
Implementation Method 1
a bright area configured to output light reflected from a surface of the semiconductor substrate
Implementation Method 2
a dark area configured to include metal wirings, output light reflected from surfaces of the metal wirings, and have brightness lower than that of the bright area
Data Source
AI summary
A semiconductor device includes a semiconductor substrate and an alignment mark. The alignment mark is provided on the semiconductor substrate and optically detectable. The alignment mark includes a bright area and a dark area. The bright area outputs light reflected from a surface of the semiconductor substrate. The dark area includes metal wirings, outputs light reflected from surfaces of the metal wirings, and has brightness lower than that of the bright area.