Hot Tile Sputtering System with Graphite Thermal Buffer
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Solution Overview
Problem
Conventional sputter coating methods for ceramic materials on glass substrates face issues such as thermal cracking, process instability, and high costs due to bonding processes, as well as nodule formation on the target surface, leading to film contamination and reduced sputtering rates.
Innovation Solution
A sputtering assembly with target tiles disposed on a low-coefficient of friction sheet, allowing for movement and heating without bonding to the backing plate, using a conductive and thermally conductive graphite sheet to manage thermal gradients and prevent tile cracking, while maintaining electrical conductivity and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ceramic tiles are bonded to a metal backing plate using conventional bonding processes, then the tiles are securely fixed and provide structural support, but the thermal gradients and differential thermal expansion cause the tiles to crack or delaminate
Solution Approach 1:
A copper intermediate layer is introduced between the ceramic tile and the backing plate. This copper layer acts as a thermal buffer that reduces thermal gradients and accommodates differential thermal expansion, preventing tile cracking and delamination while maintaining secure bonding.
Solution Approach 2:
The bonding process parameters are optimized by controlling the heating rate and temperature profile during bonding. The process heats the assembly at a controlled rate to minimize thermal shock and differential expansion stresses, then maintains a bonding temperature that ensures strong adhesion without causing tile damage.
2Stability of the object's composition
If the tiles are securely bonded to the backing plate, then structural stability is maintained, but the bonding process becomes expensive and complex involving multiple steps
Solution Approach 1:
The copper intermediate layer simplifies the bonding process by providing a readily bondable surface that adheres well to both the ceramic tile and the backing plate. This single intermediate layer replaces complex multi-layer bonding structures and reduces the number of bonding steps required.
Solution Approach 2:
The bonding process is simplified by optimizing temperature and time parameters to achieve strong bonds in fewer steps. The controlled heating profile ensures proper bonding without requiring additional processing steps or complex equipment.
3Productivity
If the tiles are allowed to heat up during sputtering, then nodule formation is reduced and sputtering efficiency improves, but thermal gradients cause the tiles to crack
Solution Approach 1:
The copper intermediate layer serves as a thermal buffer that allows the ceramic tile to heat up to optimal sputtering temperatures while preventing excessive thermal gradients. The copper conducts heat away from the tile uniformly, maintaining tile strength while enabling high-temperature sputtering for improved efficiency and reduced nodule formation.
4Reliability
If conventional bonding materials like indium solder are used, then good electrical and thermal contact is achieved, but the bonding process becomes expensive and the tiles are prone to cracking
Solution Approach 1:
The copper intermediate layer replaces expensive bonding materials like indium solder. The copper provides excellent electrical and thermal conductivity at a lower cost, while its ductility and thermal properties prevent tile cracking during heating cycles.
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 nodule formation, minimizes tile cracking, and enhances sputtering efficiency, resulting in higher quality coatings with reduced defects and lower manufacturing costs by allowing target tiles to heat uniformly and expand during the process.
Implementation Method 1
a conductive and thermally conductive graphite sheet to manage thermal gradients and prevent tile cracking
Implementation Method 2
maintaining electrical conductivity and thermal stability
Implementation Method 3
allowing target tiles to heat uniformly and expand during the process
Implementation Method 4
conventional planar magnetron sputtering of ceramic materials
Data Source
AI summary
A system and method for sputtering a coating onto a glass substrate in a vacuum deposition chamber includes providing a backing plate with a separating element disposed at the backing plate. At least one target element or tile is disposed on a surface of the separating element, wherein an expansion gap is provided to allow for expansion of the target relative to the separating element during the sputtering process. The method includes sputtering material from the target and heating the target to a substantially elevated temperature during the sputtering process. The separating element may be a sheet having a low-coefficient of friction surface, and the target may be disposed on the low-coefficient of friction surface of the separating element. The separating element may thermally insulate the target from the backing plate, whereby the target may be heated to a substantially greater temperature than the backing plate during the sputtering process.