Wafer Placement Table Connection Structure to Prevent Cracks
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Solution Overview
Problem
Conventional wafer placement tables using metal bonding layers face issues with crack occurrence and connection member detachment during manufacturing due to low adhesion between ceramic substrates, especially during grinding and load application.
Innovation Solution
A wafer placement table design featuring a connection member with a cross-sectional area increase from the upper base to the lower base, enhancing adhesion and preventing detachment, along with a power supply terminal bonded to the lateral surface of the second ceramic substrate, and a metal mesh connection member for thermal expansion compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional cylindrical connection member is used, then the structure is simple, but the adhesion between the second ceramic substrate and the connection member is low, causing cracks and detachment during grinding and load application
Solution Approach 1:
The connection member employs an asymmetric shape where the cross-sectional area increases from the upper base to the lower base. This asymmetric geometry creates a larger lateral surface area that engages with the ceramic substrate, generating mechanical interlocking and friction forces that significantly enhance adhesion strength compared to conventional cylindrical shapes.
Solution Approach 2:
The connection member features a curved lateral surface with specific geometric contours. This curvature design increases the contact area between the connection member and the ceramic substrate, distributing stress more evenly and improving mechanical interlocking. The curved geometry also helps to reduce stress concentration points that could lead to cracking during grinding operations.
2Reliability
If the connection member has a larger lateral surface area, then the adhesion is improved, but the manufacturing complexity increases
Solution Approach 1:
The invention modifies the geometric parameters of the connection member, specifically the cross-sectional area distribution along its height. By changing the shape parameters to create an increasing cross-sectional area from top to bottom, the design achieves enhanced adhesion and detachment prevention while maintaining manufacturability through standard forming processes.
3Manufacturing precision
If grinding work is performed to expose the connection member, then the wafer placement surface is prepared, but cracks may occur in the ceramic substrate due to low adhesion
Solution Approach 1:
The asymmetric shape design with increased cross-sectional area provides beforehand cushioning by creating a mechanically stronger connection between the connection member and ceramic substrate. This enhanced adhesion acts as a cushion that prevents crack propagation during subsequent grinding operations that expose the connection member upper base, thereby protecting the ceramic substrate from damage.
4Ease of manufacture
If a load is applied to the connection member during manufacturing, then the bonding is completed, but the connection member may come off due to insufficient adhesion
Solution Approach 1:
The connection member design creates a composite structural system where the asymmetric geometry itself acts as a mechanical reinforcement. The increased lateral surface area and curved geometry work together with the bonding interface to create a composite effect that significantly enhances the overall bonding strength, preventing the connection member from detaching during load-bearing bonding operations.
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 design improves adhesion between ceramic substrates, reduces crack occurrence, and prevents connection member detachment during manufacturing, ensuring stable operation and easy production with a simple connection member shape.
Implementation Method 1
a metal bonding layer that bonds a lower surface of the first ceramic substrate and an upper surface of the second ceramic substrate
Implementation Method 2
the area of the lateral surface of the connection member is larger, thus the contact area between the second ceramic substrate and the connection member is increased, and the adhesion between the second ceramic substrate and the connection member is improved
Data Source
AI summary
A wafer placement table includes a first ceramic substrate having a wafer placement surface on an upper surface; a second ceramic substrate disposed on a lower surface side of the first ceramic substrate; a metal bonding layer that bonds a lower surface of the first ceramic substrate and an upper surface of the second ceramic substrate; a connection member including an upper base and a lower base, the connection member being embedded in the second ceramic substrate with the upper base in contact with the metal bonding layer; and a power supply terminal electrically connected to the lower base of the connection member, wherein the connection member has a portion in which an area of cross section when the connection member is cut by a plane parallel to the upper base increases from a side of the upper base to a side of the lower base.