Molecular Wafer Bonding With Stepped Edges to Prevent Breakage
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Solution Overview
Problem
Existing methods of molecular bonding of wafers often result in weak areas at the edges, leading to potential ruptures and contamination during thinning or cutting, which can compromise the cleanliness of electronic component manufacturing.
Innovation Solution
A method involving the formation of a stack of layers on a substrate with successive chemical etchings to create a staircase-like structure at the edges, using etching solutions like hydrogen fluoride and nitric acid, followed by mechanical abrasion to ensure proper bonding and prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If molecular bonding is performed on wafers with rounded edges, then bonding can be achieved, but weak areas are created at the edges leading to potential breakage during thinning or cutting
Solution Approach 1:
The wafer edge is segmented into multiple stepped levels rather than a single rounded contour. This creates distinct bonding surfaces at different heights, allowing the bonding process to occur on flat, stable surfaces while the stepped structure prevents edge breakage by distributing stress across multiple levels.
Solution Approach 2:
The stepped structure is formed on the wafer edges before the molecular bonding process. This preliminary action creates predetermined bonding surfaces that ensure proper bonding occurs while preventing the formation of weak areas that would lead to breakage during subsequent thinning or cutting operations.
2Ease of manufacture
If edge rounding is performed to enable bonding, then bonding can proceed, but contamination risk increases due to potential breakage during subsequent processing
Solution Approach 1:
By segmenting the edge into stepped levels, the invention creates stable bonding surfaces that reduce the likelihood of breakage during thinning or cutting, thereby minimizing the generation of contaminating particles while maintaining ease of bonding.
Solution Approach 2:
The invention transitions from a two-dimensional rounded edge profile to a three-dimensional stepped structure. This dimensional change creates multiple bonding surfaces at different heights, enabling reliable bonding while preventing edge breakage and reducing contamination risk during subsequent processing.
3Device complexity
If standard wafer edges are used for molecular bonding, then the process is simple, but weak areas form at the edges causing breakage during thinning or cutting
Solution Approach 1:
The wafer edge is divided into multiple stepped segments rather than maintaining a simple continuous contour. This segmentation creates distinct bonding surfaces that improve edge integrity by distributing mechanical stress across multiple levels, preventing breakage during thinning or cutting while adding controlled complexity to the structure.
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
Ensures proper bonding between wafers, reduces the risk of edge breakage, and minimizes contamination, allowing for the formation of circuits within the wafers.
Implementation Method 1
successive chemical etchings of the edges of said layers from the layer of the stack most distant from the substrate
Implementation Method 2
The step is formed by mechanical abrasion
Implementation Method 3
bonding to each other of semiconductor wafers by molecular bonding
Data Source
AI summary
The present description concerns a method of manufacturing a first wafer, intended to be assembled to a second wafer by molecular bonding, including the successive steps of: forming a stack of layers at the surface of a substrate; and successive chemical etchings of the edges of said layers from the layer of the stack most distant from the substrate, across a smaller and smaller width.