Wafer Bonding Wave Control via Pressure Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low pressure molecular adhesion bonding between wafers results in variable and uncontrollable inhomogeneous deformations, leading to misalignment and defects in multilayer semiconductor structures, particularly in 3D integration, due to premature initiation of the bonding wave during alignment and contact steps.
Innovation Solution
A method involving mechanical alignment and contact of wafers in an environment above a predetermined pressure threshold, followed by a reduction to a lower pressure to initiate the bonding wave, ensuring controlled propagation and minimizing deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If molecular adhesion bonding is carried out at low pressure (≤1 millibar), then bonding energy is high and bonding wave propagation is rapid, but inhomogeneous deformations and misalignment occur due to premature bonding wave initiation during alignment and contact steps
Solution Approach 1:
The bonding process is segmented into distinct pressure phases: alignment and contact occur at atmospheric pressure, followed by a pressure reduction to initiate controlled bonding wave propagation at the bonding interface. This segmentation prevents premature bonding during alignment while ensuring high bonding energy during the bonding phase.
Solution Approach 2:
Alignment and contact operations are performed preliminarily at atmospheric pressure before the bonding wave is initiated. This preliminary action at higher pressure prevents accidental bonding wave initiation, ensuring that wafers are properly positioned before the low-pressure bonding phase begins.
2Productivity
If bonding wave propagation is initiated during alignment and contact operations at low pressure, then bonding occurs, but uncontrollable inhomogeneous deformations are generated in the wafers
Solution Approach 1:
The pressure parameter is dynamically changed during the process: maintained at atmospheric pressure during alignment and contact, then reduced to low pressure to initiate controlled bonding wave propagation. This parameter change ensures that bonding occurs only when intended, preventing uncontrolled deformations while maintaining high bonding speed.
3Ease of manufacture
If wafers are bonded by molecular adhesion at low pressure without pressure control during alignment, then bonding is achieved, but misalignment of microcomponents occurs due to inhomogeneous deformations
Solution Approach 1:
The pressure condition is made dynamic rather than static: atmospheric pressure during alignment and contact operations, then transition to low pressure for bonding wave initiation. This dynamic pressure control maintains process simplicity while ensuring microcomponent alignment precision by preventing deformations during the critical alignment phase.
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 risk of misalignment and defects, achieving high-quality multilayer semiconductor wafers with minimal residual alignment offsets, ensuring precise microcomponent alignment and functionality, such as maintaining coloration function in image sensors.
Implementation Method 1
molecular adhesion bonding carried out at low pressure (also referred to as LPB for 'Low Pressure Bonding') between two 'wafers'
Implementation Method 2
the force necessary for initiating the propagation of a bonding wave between two wafers is less than that required at ambient pressure. Furthermore, the lower the pressure, the more rapidly the bonding wave propagates between the wafers
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2E
AI summary
Method for molecular adhesion bonding between at least a first wafer (20) and a second wafer (30) comprising at least a step of mechanical alignment, a step of bringing the two wafers (20, 30) in contact and a step of initiating the propagation of a bonding wave between the two wafers. During the steps of mechanical alignment and bringing the two wafers in contact, the wafers are placed in an environment at a first pressure (P1) greater than or equal to a predetermined pressure threshold value. During the step of initiating the propagation of a bonding wave, the wafers (20, 30) are placed in an environment at a second pressure (P2) less than the said predetermined pressure threshold value.