Ceramic Electrode-Embedded Structure With Buffer Layer Against Thermal Cracks
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Solution Overview
Problem
Conventional electrode-embedded members in semiconductor manufacturing apparatuses experience cracking due to thermal expansion coefficient differences between materials, particularly between tungsten and aluminum nitride, leading to stress concentration and crack propagation.
Innovation Solution
Incorporating a buffer member with a mixed structure of ceramic and tungsten/molybdenum materials within the substrate to reduce the thermal expansion coefficient difference between the connection member and the substrate, thereby reducing stress concentration and preventing crack propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal electrode is embedded in a ceramic substrate with a terminal hole, then electrical connection is achieved, but stress concentration occurs at the connection member edge due to thermal expansion coefficient differences
Solution Approach 1:
A buffer member made of tungsten or molybdenum is introduced as an intermediary between the connection member and the ceramic substrate. This buffer member has a thermal expansion coefficient intermediate between the connection member and substrate, acting as a stress-absorbing layer that prevents direct stress transmission and crack propagation at the interface.
Solution Approach 2:
The buffer member is formed as a composite structure containing ceramic particles dispersed in a metal matrix (tungsten or molybdenum). This composite material combines the high melting point and structural stability of ceramics with the ductility and stress-absorption capabilities of metals, creating a material that can withstand thermal cycling without cracking.
2Duration of action of moving object
If the substrate is subjected to repeated thermal cycling, then the electrode-embedded member functions properly, but cracks propagate from the connection member edge into the substrate
Solution Approach 1:
The buffer member is positioned beforehand at the critical interface region where thermal stress concentrates during thermal cycling. It serves as a pre-positioned cushioning layer that absorbs and distributes thermal stresses before they can propagate into the ceramic substrate, preventing crack initiation and propagation during repeated heating and cooling cycles.
Solution Approach 2:
The invention changes the thermal expansion parameter by introducing a buffer member with intermediate thermal expansion properties. This parameter modification creates a gradual transition in thermal expansion coefficients from the connection member to the substrate, reducing the abrupt stress concentration that occurs during thermal cycling and preventing crack propagation.
3Device complexity
If the connection member is directly connected to the electrode without a buffer member, then device complexity is reduced, but oxidation proceeds from the back surface side causing crack formation
Solution Approach 1:
The buffer member acts as a protective intermediary layer between the connection member and the oxidizing environment. It serves as a barrier that prevents oxidation from proceeding from the back surface side of the connection member, thereby eliminating the harmful oxidation effect without significantly increasing device complexity.
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 buffer member effectively suppresses crack occurrence by reducing thermal expansion coefficient differences, enhancing the structural integrity of the electrode-embedded member under high-temperature conditions.
Implementation Method 1
the buffer member contains at least a ceramic material and at least one of tungsten and molybdenum, and the buffer member covers at least part of an edge of the connection member... reducing the thermal expansion coefficient difference between the connection member and the substrate
Data Source
AI summary
An electrode-embedded member 1 includes a ceramic-made substrate 2, an electrode 3, a connection member 4 containing at least one of tungsten and molybdenum and embedded in the substrate 2 in a state in which a first principal surface 4a faces the electrode 3 and is electrically connected to the electrode 3, and a hole portion 5 extending from an outer surface of the substrate 2 to a second principal surface 4b of the connection member 4. A buffer member 10 embedded in the substrate 2 contains at least a ceramic material forming the substrate 2 and a conductive material containing at least one of tungsten and molybdenum as a constituent element. The buffer member 10 covers at least part of an edge of the connection member 4.