Semiconductor Wafer Laser Marking for Crystal Orientation
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Solution Overview
Problem
The existing methods for indicating crystal orientation on semiconductor wafers, such as flat zones or notches, can lead to defects and particle issues during subsequent processing steps, and are not efficiently aligned during implantation processes.
Innovation Solution
The use of laser marks with specific depths and positions on the wafer surfaces to indicate crystal orientation, where a first laser mark is deeper than a second mark, and both are used in conjunction with indicia like alphanumeric codes or QR codes to uniquely identify the wafer, allowing for precise alignment without the need for flat zones or notches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flat zones or notches are formed on the wafer edge to indicate crystal orientation, then alignment during implantation is achieved, but defects and particle issues occur during subsequent processing steps
Solution Approach 1:
The patent extracts the crystal orientation indication function from the wafer edge geometry (flat zones/notches) and relocates it to the wafer center using laser marks. This removes the harmful edge modifications while preserving the alignment indication function. The laser marks are formed at the center of the wafer surface, eliminating the need for edge grinding and notch formation that cause defects and particles.
Solution Approach 2:
The patent replaces the mechanical method of forming flat zones and notches through edge grinding with a laser-based marking system. The laser marks are formed by ablation or melting of the wafer surface material at the center, substituting mechanical edge modification with optical field-based marking that does not generate particles or defects.
2Measurement precision
If edge grinding is performed to create flat zones for alignment indication, then crystal orientation can be determined, but the wafer becomes more susceptible to breakage during polishing
Solution Approach 1:
The patent extracts the alignment indication function from the wafer edge and relocates it to the wafer center. By forming laser marks at the center of the wafer surface, the method eliminates the need for edge grinding that weakens the wafer structure. The wafer maintains its full edge integrity and strength during subsequent polishing operations.
Solution Approach 2:
The patent performs laser marking at the wafer center before edge grinding and polishing operations. This preliminary action establishes the alignment indication without requiring subsequent edge modifications, allowing the wafer to maintain its structural strength throughout the processing sequence.
3Measurement precision
If multiple laser marks are formed at different depths to indicate crystal orientation, then alignment accuracy is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies different laser marking depths at different locations on the wafer surface. A first laser mark is formed at a greater depth than a second laser mark, creating local quality variations that encode crystal orientation information. This depth differentiation enables precise alignment indication while maintaining a relatively simple single-step laser processing approach.
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 minimizes wafer defects, reduces the risk of breakage during polishing, and enhances the accuracy of crystal orientation alignment, improving the uniformity and efficiency of semiconductor chip fabrication processes.
Implementation Method 1
a laser mark at a determined position on a front surface or on a back surface of the wafer
Data Source
AI summary
A wafer can be provided to include a single crystalline semiconductor material with a predetermined crystal orientation. The wafer can include a laser mark at a determined position on a front surface or on a back surface of the wafer, where the determined position is configured to indicate the predetermined crystal orientation of the single crystalline semiconductor material.