3D IC Substrate Alignment Using Visible Light Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional IC device substrate alignment methods face challenges in detecting alignment patterns obstructed by opaque materials, particularly in three-dimensional IC fabrications, due to limited accuracy and resolution caused by IR wavelength limitations, which complicates the bonding process and increases fabrication costs.
Innovation Solution
The use of optical detectors placed to face alignment patterns on the outside of IC device substrates, allowing direct detection of alignment patterns on both front and back sides without obstruction, utilizing visible light for improved accuracy and precision in alignment, and incorporating auxiliary structures like notches and through holes for enhanced alignment capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If IR imaging apparatus is used to detect alignment patterns through opaque material, then detection capability is improved, but measurement precision deteriorates due to IR wavelength limitations
Solution Approach 1:
The invention extracts the alignment pattern detection function from the front side (obstructed by opaque material) and relocates it to the back side of the substrate, where detection can occur without obstruction. The alignment patterns are formed on the back side, allowing direct optical detection without passing through opaque interconnection structures.
Solution Approach 2:
The invention replaces the IR imaging system (electromagnetic radiation in IR range) with a visible light optical detection system. By using visible light with shorter wavelength, the system achieves higher resolution and precision for alignment pattern detection, eliminating the wavelength-related precision limitations of IR detection.
2Ease of operation
If alignment patterns are formed on the front side of substrate, then alignment functionality is provided, but detection is obstructed by opaque metallic material
Solution Approach 1:
The invention inverts the conventional approach by forming alignment patterns on the back side of the substrate instead of the front side. This inversion allows the alignment patterns to be detected from the back side without being obstructed by opaque metallic interconnection structures that are present on the front side.
3Difficulty of detecting and measuring
If additional processes are used to remove opaque material for visibility, then detection capability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention extracts the alignment pattern formation step from the front side processing sequence and places it on the back side, eliminating the need for additional material removal processes. The alignment patterns are formed directly on the back side after substrate preparation, avoiding the need to remove opaque metallic material.
4Difficulty of detecting and measuring
If IR wavelength is used for detection, then detection capability is maintained, but resolution deteriorates below required 0.1 um threshold
Solution Approach 1:
The invention substitutes the IR detection system with a visible light optical detection system. Visible light has a shorter wavelength than IR radiation, enabling the optical system to resolve features smaller than the 0.1 um threshold required for modern semiconductor processes, thereby achieving the necessary alignment precision.
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 approach enables precise alignment of IC device substrates with increased accuracy and reduced costs by eliminating the need for IR detection, allowing for more efficient three-dimensional IC fabrication with improved resolution and available space for IC features.
Implementation Method 1
A first optical detector and a second optical detector are applied to detect the first and second alignment patterns
Data Source
AI summary
Alignment methods of IC device substrates. A first IC device substrate has a first front side for defining a plurality of first IC features, a first backside opposite the first front side, and a first alignment pattern formed on the first front side or the first backside. A second IC device substrate has a second front side for defining a plurality of second IC features, a second backside opposite the second front side, and a second alignment pattern formed on the second front side or the second backside. A first optical detector and a second optical detector are applied to detect the first and second alignment patterns, so as to align the first and second IC device substrates. Specifically, the first and second alignment patterns face toward the first and second optical detectors in opposite directions.