Compliant Chuck Edge Ring for Void-Free Wafer Bonding
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Solution Overview
Problem
Voids formed between the outer edge portions of bonded semiconductor wafers lead to poor bonding reliability, as existing bonding apparatuses fail to effectively manage stress and restrict movement at the wafer edges, resulting in incomplete bonding.
Innovation Solution
A compliant ring made of materials like silicon oxynitride, polymers (e.g., PDMS), or silicon carbide is mounted around the wafer holder, extending radially to create a larger contact area and restrict relative movement between wafers, ensuring the bond propagates uniformly to the edge regions, reducing voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bonding apparatus brings wafer centers into contact to initiate bonding, then bonding can proceed from center to edge, but voids form at the outer edge portions leading to poor bonding reliability
Solution Approach 1:
A compliant ring made of flexible material (such as polyimide or PDMS) is mounted around the wafer holder. This flexible ring contacts the wafer edge region and allows controlled movement during bonding while maintaining edge contact, preventing void formation at the wafer periphery and improving bonding reliability
Solution Approach 2:
The compliant ring acts as an intermediary element between the wafer holder and the wafer edge. It mediates the interaction by providing compliant support that restricts excessive wafer edge movement while allowing the bonding process to proceed, thereby eliminating the harmful voids without interfering with the overall bonding mechanism
2Ease of operation
If the wafer holder area is kept small for ease of operation, then handling is simplified, but the contact area is insufficient to restrict wafer edge movement and prevent voids
Solution Approach 1:
The wafer holder system is segmented into two functional components: a compact vacuum chuck for wafer handling and a separate compliant ring for edge support. This segmentation allows the chuck to remain small for ease of operation while the extended compliant ring provides the additional contact area needed to restrict wafer edge movement and ensure uniform bonding
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
The compliant ring enhances bonding reliability by preventing edge voids and ensuring a complete bond across the wafer edges, improving the overall quality and reliability of the semiconductor wafer bonding process.
Implementation Method 1
The front surface of the upper wafer holder is configured to suck a primary surface of a first wafer
Data Source
AI summary
An apparatus for handling a semiconductor wafer includes an upper wafer holder that has a front surface, and a compliant ring that is mounted around the upper wafer holder and has a front surface. The front surface of the compliant ring is flush with the front surface of the upper wafer holder and extends from the front surface of the upper wafer holder in a radial direction without extending beyond the front surface of the wafer holder in an axial direction. A method includes providing a first wafer with a bonding surface and back surface, the back surface of the wafer in contact with the front surfaces of the wafer holder and the compliant ring. The first wafer contacts a second wafer so a bond forms between the wafers in a radial direction, the compliant ring flexibly restricting the movement of the first wafer relative to the second wafer.