Wafer Bonding Plasma Activation Stage Contact Area Reduction
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Solution Overview
Problem
The conventional plasma activation method for wafer bonding leads to an increase in particles on the back surface of wafers, which can re-attach during cleaning, causing surface defects and reduced bonding strength due to the large contact area between the wafer and the stage.
Innovation Solution
The method involves performing plasma activation with the back surface of the wafers in point or line contact with the stage, reducing the contact area and using a batch cleaning apparatus to prevent re-attachment of particles, thereby enhancing bonding strength and reducing surface defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wafer back surface is placed on a stage with large contact area during plasma activation, then the wafer is stable and properly positioned, but particles increase on the back surface due to contact with the stage
Solution Approach 1:
The stage contact surface is segmented into multiple discrete contact points (protrusions) rather than a continuous large contact area. This segmentation reduces the total contact area between the wafer back surface and the stage, thereby minimizing particle generation while still providing sufficient positioning stability through multiple distributed contact points.
Solution Approach 2:
The stage is designed with localized protrusions that provide contact only at specific points rather than across the entire back surface. This local quality approach concentrates the necessary mechanical support and positioning functions at discrete locations, reducing the overall contact area and associated particle contamination while maintaining local stability where needed.
2Strength
If plasma activation is performed to clean the wafer surface and increase bonding strength, then bonding strength increases, but particles are generated on the back surface that can re-attach during cleaning
Solution Approach 1:
The harmful factor (particles) is extracted or removed from the system by minimizing its source. By designing the stage with reduced contact area protrusions, the generation of particles during plasma activation is minimized at the source, preventing subsequent re-attachment to the bonded surface during cleaning operations.
Solution Approach 2:
The design proactively prevents particle generation before it can occur during plasma activation. By using a stage with minimal contact area protrusions from the beginning, the preliminary anti-action reduces particle contamination at the source, preventing the need for additional particle removal steps and avoiding re-attachment issues.
3Manufacturing precision
If batch cleaning is performed after plasma activation to remove particles, then cleaning effectiveness increases, but particles from the back surface can re-attach to the front surface
Solution Approach 1:
The stage design with reduced contact area protrusions performs preliminary action by minimizing particle generation during plasma activation before the cleaning step occurs. This preliminary prevention reduces the particle load that would otherwise need to be removed during batch cleaning and prevents re-attachment issues.
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 significantly inhibits the increase of particles on the back surface during plasma activation, prevents re-attachment, and improves the quality of bonded wafers by increasing bonding strength and reducing surface defects.
Implementation Method 1
gas ions, such as hydrogen ions or rare gas ions, are implanted from a front surface of one of the silicon wafers (a bond wafer) to form a micro bubble layer (an enclosed layer) in the interior of the wafer
Implementation Method 2
it is understood that since a hydroxyl group is easy to bond to an Si dangling bond on the exposed clean surface, the wafer bonding strength in the state where the wafers are in close contact is increased
Implementation Method 3
a heat treatment (a delamination heat treatment) is then performed to cleave one of the wafers (the bond wafer) along the micro bubble layer so that the bond wafer is delaminated into a thin film
Implementation Method 4
A heat treatment (a bonding heat treatment) is then performed to strengthen a bond between the wafers
Data Source
Figure 1(a)~1(f)
Figure 2~3
Figure 4~5
AI summary
The present invention is a method for manufacturing a bonded wafer, including performing a plasma activation treatment on at least one of the bonded surfaces of the bond wafer and the base wafer before bonding, wherein the plasma activation treatment is performed while a back surface of at least one of the bond wafer and the base wafer is placed on a stage with the back surface being in point contact or line contact with the stage. The method can inhibit increase in attached substances such as particles on the back surface of a wafer during the plasma activation treatment, and prevent re-attachment of the attached substances to the bonded surface of the wafer, particularly when the wafer after the plasma activation treatment is cleaned with a batch cleaning apparatus.