Semiconductor Alignment Mark Texture for CMP Integrity
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Solution Overview
Problem
Chemical-mechanical polishing processes during semiconductor fabrication often modify and remove alignment marks, leading to registration issues between layers, as these marks lack underlying textures similar to the integrated circuitry, causing dishing and other problematic behaviors.
Innovation Solution
Incorporating textures within alignment mark locations that are consistent with the underlying integrated circuitry textures to prevent or alleviate modification during polishing processes, ensuring the alignment marks remain intact and functional.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical-mechanical polishing is used to planarize the wafer surface, then the surface flatness is improved, but the alignment marks are removed or modified
Solution Approach 1:
The patent applies different surface textures to different regions: alignment mark locations receive a first texture that protects them during polishing, while non-alignement regions receive a second texture optimized for planarization. This local differentiation allows the polishing process to flatten the overall surface while preserving alignment marks through their protective texture.
Solution Approach 2:
The alignment marks are textured before the polishing process occurs. This preliminary texturing creates a protective surface characteristic that prevents the polishing apparatus from removing or modifying the alignment marks during subsequent planarization steps.
2Ease of manufacture
If alignment marks are placed on regions without underlying textures, then the fabrication process is simplified, but the alignment marks are susceptible to polishing damage
Solution Approach 1:
Rather than requiring all regions to have protective textures, the patent applies texture only where needed - specifically at alignment mark locations. This localized approach maintains fabrication simplicity while providing durability exactly where required for alignment functionality.
3Reliability
If textures are added to alignment mark locations, then the alignment marks are protected during polishing, but the fabrication process complexity increases
Solution Approach 1:
The patent implements texture formation in a localized manner at alignment mark locations rather than across the entire wafer. This localized texturing minimizes the additional fabrication complexity while providing the necessary protection only where alignment marks exist.
Solution Approach 2:
The texture is formed at alignment mark locations before polishing occurs, allowing the texture to serve as a protective measure throughout the polishing process. This preliminary texturing integrates smoothly into the existing fabrication sequence without requiring post-polishing corrections.
Data Source
AI summary
Some embodiments include a semiconductor package. The semiconductor package has a semiconductor die with a primary region which includes integrated circuitry, and with an edge region which includes a portion of an alignment mark location. The portion of the alignment mark location includes a segment of an alignment mark. The alignment mark includes a pattern of lines and spaces, with the lines extending along a first direction. The portion of the alignment mark location also includes a texture having a pattern other than lines extending along either the first direction or along a second direction substantially orthogonal to the first direction. Some embodiments include methods for alignment marking semiconductor wafers.