Rotatable Chuck Alignment for Substrate Bonding Accuracy
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Solution Overview
Problem
Conventional semiconductor bonding alignment techniques face challenges in achieving high accuracy due to mechanical movement errors and substrate deformation, particularly with larger substrates, and require complex high-precision sensors to minimize alignment errors.
Innovation Solution
An apparatus and method utilizing a press assembly with a rotatable chuck and an objective lens group made of light-transmissive material to observe and align substrates, allowing for relative movement of chucks based on observed alignment marks, which reduces the need for high-precision components and enables global alignment accuracy by adjusting chucks before bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional alignment methods with objective lens pairs are used, then alignment accuracy is maintained at micron level, but mechanical movement errors and substrate deformation errors increase with larger substrates, affecting final alignment accuracy
Solution Approach 1:
The patent replaces the conventional mechanical alignment system with an optical field-based alignment system. By projecting a reference grid pattern onto the substrate and capturing images of the alignment marks relative to this grid, the system achieves alignment without relying on mechanical precision of objective lens pairs. The optical field serves as a stable reference that is immune to mechanical movement errors and substrate deformation.
Solution Approach 2:
The patent creates an optical copy of the alignment marks by imaging them through the objective lens onto a sensor plane. Multiple images of alignment marks are captured at different positions, and these optical copies are processed to calculate relative positions and deviations. This copying approach allows error compensation through computational methods rather than relying on mechanical precision.
2Manufacturing precision
If high-precision sensors are used to measure substrate positions, then alignment accuracy is improved, but device complexity increases significantly
Solution Approach 1:
The patent replaces complex high-precision mechanical sensors and calibration systems with a simplified optical imaging system. By using a reference grid pattern projected onto the substrate and standard imaging capabilities, the system achieves high alignment accuracy without requiring complex sensor arrays or extensive calibration procedures. The complexity is reduced by shifting from mechanical measurement to optical field analysis.
3Manufacturing precision
If conventional alignment methods are used, then local alignment marks can be aligned, but global alignment errors caused by substrate deformation cannot be detected
Solution Approach 1:
The patent divides the substrate alignment problem into multiple measurable components by capturing images of multiple alignment marks at different locations and orientations. The reference grid pattern is segmented into multiple regions, and alignment deviations are calculated independently for each region. This segmentation allows detection of both local and global alignment errors by comparing deviations across different segments of the substrate.
Solution Approach 2:
The patent adds a dimensional reference framework by projecting a two-dimensional grid pattern onto the substrate surface. This reference grid provides a global coordinate system that spans the entire substrate, enabling detection of large-scale deformation and orientation errors. By incorporating this additional dimensional reference, the system can detect global alignment errors that would be invisible to conventional point-to-point alignment methods.
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 simplifies the apparatus, reduces complexity, and effectively controls global alignment errors, including those caused by substrate deformation, by ensuring accurate alignment of substrates without relying on extensive high-precision sensors.
Implementation Method 1
one of the first and second chucks proximate the objective lens group is made of a light-transmissive material. The objective lens group is configured to observe an alignment situation between the first and second substrates within the press assembly
Data Source
AI summary
An apparatus and method for bonding alignment are provided. The apparatus for bonding alignment includes a press assembly and an objective lens group (105) disposed on one side of the press assembly. The press assembly includes a first chuck (103) and a rotatable second chuck (104). When support surfaces of the first and second chucks are not parallel to each other, the second chuck is rotated to make the two support surfaces parallel. A first substrate (301) is then loaded on the first chuck, and alignment marks (302) on the first substrate are observed using the objective lens group disposed on one side of the press assembly. A second substrate (501) is loaded on the second chuck, and alignment marks (502) on the second substrate are also observed with the objective lens group. Based on an observation result by the objective lens group, the two substrates are moved so that the alignment marks thereon are aligned and hence the two substrates themselves are aligned. In this method, the chucks are adjusted, prior to the alignment of the substrates. This dispenses with the need for employment of high-precision components and reduces the complexity of the apparatus. Moreover, adjusting the chucks first can ensure control of a global alignment accuracy between the substrates, and in particular, can reduce wedge-shaped errors between the substrates that may result from deformations of the substrates during bonding.