Semiconductor Wafer Bonding Surface Reconditioning
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Solution Overview
Problem
Semiconductor wafers with micro structural defects on bonding interface surfaces, caused by micromachining processes, pose challenges for reliable bonding, particularly in fusion bonding, leading to potential bond failure and scrap materials.
Innovation Solution
A non-abrading method involving the formation and removal of an oxide layer, such as silicon dioxide, below the defect level to expose a clean bonding surface, allowing for reconditioning without damaging existing micromachined structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional abrading methods are used to remove surface defects, then bonding interface quality is improved, but micromachined structures are damaged
Solution Approach 1:
The patent replaces mechanical abrading methods with a chemical oxidation process. An oxide layer is grown on the semiconductor wafer surface through thermal or chemical oxidation, which selectively removes microstructural defects without mechanically contacting or damaging the micromachined structures. The oxide layer is then removed chemically, leaving a clean bonding surface while preserving the underlying micromachined features.
Solution Approach 2:
The oxide layer serves as an intermediary medium that facilitates defect removal without direct contact between the wafer surface and the removal mechanism. The oxidation process creates a removable oxide layer that encapsulates and removes defects, while the subsequent chemical removal of the oxide layer leaves the bonding interface clean without requiring mechanical abrasion that would damage sensitive structures.
2Productivity
If wafers with micro structural defects are used for bonding, then production efficiency is maintained, but bond reliability deteriorates
Solution Approach 1:
The oxidation process is performed as a preliminary treatment before bonding to proactively eliminate microstructural defects that would otherwise compromise bond reliability. By growing and removing the oxide layer in advance, the method ensures defect-free bonding interfaces, preventing bond failures and reducing scrap rates without requiring extensive inspection or rework.
Solution Approach 2:
The method changes the physical and chemical parameters of the wafer surface through oxidation. The oxidation process modifies the surface chemistry and topology by growing an oxide layer that consumes and removes defective regions. After oxide removal, the surface parameters are restored to optimal bonding conditions, ensuring high bond reliability while maintaining production throughput.
3Manufacturing precision
If oxide layer formation and removal is performed, then surface defects are eliminated, but process complexity increases
Solution Approach 1:
The oxidation process serves multiple functions simultaneously: it grows a protective oxide layer, selectively removes microstructural defects, and prepares the surface for subsequent bonding. The same thermal or chemical oxidation equipment used for other semiconductor processing steps can be utilized, eliminating the need for specialized defect removal equipment and reducing overall process complexity.
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 method increases line yield and reduces scrap by ensuring a defect-free bonding interface, facilitating stronger and more reliable bonding without damaging the micromachined features, thus enhancing the fabrication process efficiency.
Implementation Method 1
forming an oxide layer (such as a silicon dioxide layer) on the bonding interface surface to a depth below the level of the defect
Data Source
AI summary
A non-abrading method to facilitate bonding of semiconductor components, such as silicon wafers, that have micro structural defects in a bonding interface surface. In a preferred method, micro structural defects are removed by forming an oxide layer on the bonding interface surface to a depth below the level of the defect, and then removing the oxide layer to expose a satisfactory surface for bonding, thereby increasing line yield and reducing scrap triggers in fabrication facilities.