Semiconductor Wafer Protective Layer Layout for Cleaner Blade Sawing
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Solution Overview
Problem
The presence of a large quantity of protective layers in scribe lines during semiconductor wafer fabrication leads to increased maintenance and cleaning frequency of saw blades, reducing production capacity and increasing fabrication costs due to sticking issues during blade sawing.
Innovation Solution
A method is introduced where a protective layer is formed on a semiconductor wafer with varying thicknesses in scribe lines, allowing for controlled exposure and development to ensure the layer above the second test structure is thinner than above the first, preventing sticking to saw blades and optimizing production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is formed covering the scribe line, then the wafer is protected during processing, but the protective layer sticks to saw blades during blade sawing
Solution Approach 1:
The protective layer is configured with different thicknesses in different regions: a first thickness in the chip area providing protection, and a second thickness (smaller than the first) in the scribe line area reducing adhesion to saw blades. This local differentiation resolves the contradiction by maintaining protection where needed while minimizing sticking where it causes problems.
Solution Approach 2:
The protective layer is segmented into distinct thickness regions corresponding to different functional areas of the wafer. The lithography process creates this segmentation by selectively exposing different areas, resulting in a protective layer with spatially varying thickness that addresses both protection and sawing requirements.
2Productivity
If the protective layer thickness is reduced in scribe lines, then saw blade sticking is prevented, but the protective coverage in chip areas may be compromised
Solution Approach 1:
The protective layer maintains full thickness in chip areas to ensure adequate protection, while locally reducing thickness only in scribe line areas where saw blade contact occurs. This selective thickness modification preserves protective coverage where critical while eliminating sticking problems where they occur.
3Ease of manufacture
If a uniform protective layer is formed, then fabrication is simpler, but the protective layer causes saw blade sticking in scribe lines
Solution Approach 1:
The varying thickness pattern is built into the protective layer during the formation process itself through selective lithography exposure, rather than requiring subsequent mechanical or chemical modification. This preliminary structuring achieves the thickness differentiation needed to prevent sticking while maintaining ease of manufacture.
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 reduces the quantity of protective layer in scribe lines, preventing blade sticking and enhancing production capacity while minimizing fabrication costs.
Implementation Method 1
The protective layer is exposed and developed, such that a thickness of the protective layer remained above the first test structure is greater than that of the protective layer remained above the second test structure
Data Source
AI summary
The embodiments relate to a semiconductor structure and a fabrication method thereof. The fabrication method includes: providing a wafer, in the wafer there being provided with a scribe line, in the scribe line there being provided with a test pad, a first test structure, and a second test structure; the second test structure being positioned below the first test structure, and a transverse pitch between the second test structure and the first test structure being at least equal to a width of the test pad; forming a protective layer on the wafer, the protective layer at least covering the scribe line; and performing exposure and development on the protective layer, such that a thickness of the protective layer remained above the first test structure is greater than that of the protective layer remained above the second test structure.