MEMS Metallization Kerf and Passivation for Crack-Free Separation
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Solution Overview
Problem
The existing methods for manufacturing microelectromechanical systems (MEMS) face challenges in achieving high wafer yield and minimizing mechanical defects during the separation process, as breaking the wafer can lead to cracks in the back end of line (BEOL) layers, resulting in production rejections and operational drifts.
Innovation Solution
A method involving the dual use of release etching and passivation steps, where a kerf is created in the metallization layer structure to facilitate separation while also releasing functional elements, and a passivation layer is deposited on the kerf and notch surfaces to protect the metallization layer and prevent cracks, allowing for precise and robust separation without additional time or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer is broken for separation, then the separation process is completed, but cracks occur in the BEOL layers resulting in mechanical defects
Solution Approach 1:
A kerf is created in the metallization layer structure before the actual separation process. This preliminary action provides a predefined separation path that guides the breaking process, ensuring that cracks follow the kerf line rather than propagating randomly through the BEOL layers, thus completing separation while minimizing mechanical defects
Solution Approach 2:
The kerf acts as an intermediary structure between the intact wafer and the separated dies. It serves as a controlled weakness that facilitates separation along a predetermined path, mediating the separation process to prevent uncontrolled cracking in the BEOL layers
2Reliability
If additional protection steps are added to prevent cracks, then mechanical defects are reduced, but manufacturing time and cost increase
Solution Approach 1:
The release etching step serves dual purposes: it releases the functional elements from the sacrificial layer and simultaneously creates the kerf in the metallization layer structure. This merging of functions achieves crack prevention without adding separate processing steps, maintaining manufacturing efficiency while improving mechanical reliability
Solution Approach 2:
The kerf structure serves multiple functions: it acts as a separation guide, a crack arrestor, and a stress relief feature. By making the kerf multi-functional, the patent achieves comprehensive protection against mechanical defects without requiring additional dedicated protection steps
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 enhances the separation performance, reduces mechanical defects, and increases the robustness of MEMS by preventing cracks and corrosion, leading to higher wafer yield and extended product lifetime.
Implementation Method 1
Release etching is performed from a surface of the metallization layer structure towards the processed semiconductor substrate, for generating a kerf in the metallization layer structure
Implementation Method 2
depositing a passivation layer (e.g., an insulator layer) at a first surface (e.g., a notch surface) of the optional notch and at a second surface (e.g., a kerf surface) of the kerf
Data Source
AI summary
A semiconductor element includes a processed substrate arrangement including a processed semiconductor substrate and a metallization layer arrangement on a main surface of the processed semiconductor substrate. The semiconductor element further includes a passivation layer arranged at an outer border of the processed substrate arrangement.