Integrated Circuit Wafer Assembly Without Edge Roll-Off Defects
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Solution Overview
Problem
The existing methods for assembling integrated circuit wafers are inefficient due to edge roll-off issues, which lead to defects and require multiple costly steps, including mechanical trimming and thermocompression, and are not compatible with all types of wafers, especially those with ultra-low dielectric constants.
Innovation Solution
A method involving the removal by abrasion of a peripheral portion of one integrated circuit wafer's assembly face to create a hollow with a rounded surface, allowing direct bonding without defects, followed by molecular adhesion and optional annealing, which reduces the number of assembly steps and eliminates the need for thermocompression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If mechanical trimming is used to eliminate edge roll-off, then the edge roll-off is removed, but defects are generated on the assembly face
Solution Approach 1:
The patent replaces mechanical trimming with chemical-mechanical polishing (CMP) to eliminate edge roll-off. The CMP process uses a combination of mechanical abrasion and chemical reaction to remove material, producing a defect-free surface. The polishing pad with abrasive particles chemically reacts with the wafer material while mechanically removing it, avoiding the fragment generation associated with mechanical cutting.
Solution Approach 2:
The patent changes the processing parameters from mechanical cutting (high force, abrupt removal) to chemical-mechanical polishing (controlled chemical reaction combined with gentle abrasion). This parameter change transforms the material removal mechanism to achieve both edge roll-off elimination and defect-free surfaces, suitable for hybrid bonding applications.
2Manufacturing precision
If chemical mechanical polishing is used to remove defects, then assembly face quality improves, but edge roll-off is generated again
Solution Approach 1:
The patent performs chemical-mechanical polishing as a preliminary step before bonding to eliminate edge roll-off and generate a defect-free surface. By addressing both the shape issue (edge roll-off) and surface quality (defects) in a single preliminary processing step, the method prevents the need for subsequent corrective actions that would compromise either shape or quality.
Solution Approach 2:
The patent employs a composite processing approach combining chemical reaction and mechanical polishing in the CMP process. This composite method simultaneously achieves surface defect removal and edge roll-off elimination, as the chemical component removes material cleanly while the mechanical component shapes the edge, avoiding the trade-off between the two objectives.
3Manufacturing precision
If multiple processing steps are used to eliminate edge roll-off and remove defects, then assembly quality improves, but manufacturing complexity and time increase
Solution Approach 1:
The patent merges the functions of edge roll-off elimination and defect removal into a single chemical-mechanical polishing step. This consolidated process simultaneously addresses both the shape issue (edge roll-off) and surface quality issue (defects), reducing the number of processing steps from multiple separate operations to one integrated process, thereby simplifying manufacturing while maintaining high assembly quality.
4Strength
If thermocompression is used to bond wafers, then bonding strength is achieved, but the process is time-consuming and costly
Solution Approach 1:
The patent replaces thermocompression bonding with direct bonding at reduced temperature and pressure. The chemical-mechanical polishing creates such a defect-free, highly smooth surface that direct molecular adhesion and chemical bonding can occur without the need for intensive thermal and mechanical compression, significantly reducing bonding time and cost while maintaining bonding strength.
Solution Approach 2:
The patent changes the bonding parameters from high temperature and high pressure (thermocompression) to low temperature and low pressure (direct bonding). This parameter change is enabled by the preliminary chemical-mechanical polishing that creates an ideal bonding surface, allowing strong bonds to form under milder conditions, thus reducing assembly time and manufacturing cost.
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 enables rapid, defect-free assembly of integrated circuit wafers, improves bonding quality, and reduces waste by allowing for early detection of defects before irreversible bonding, thus lowering manufacturing costs.
Implementation Method 1
a removal by abrasion of a portion of an assembly face of a first integrated circuit wafer on a perimeter of the first wafer
Implementation Method 2
a bonding of the assembly face of the first wafer to an assembly face of a second integrated circuit wafer
Data Source
AI summary
According to one aspect, there is proposed a method for assembling two integrated circuit wafers. The method includes removing by abrasion of a portion of an assembly face of a first wafer on a perimeter of the first wafer, and bonding the assembly face of the first wafer to an assembly face of a second integrated circuit wafer.