Plasma Boat Attenuation Structure for Uniform Wafer Coating
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Solution Overview
Problem
Plasma-enhanced chemical vapor deposition (PECVD) boats fail to achieve uniform coating on wafers due to non-uniform plasma intensity distribution, resulting in excessively thick deposits at the edge regions of wafer holders and boat plates, which hinders homogeneous distribution of the coating.
Innovation Solution
Incorporating attenuation elements between neighboring boat plates, electrically insulated from them, to partially attenuate plasma deposition in the edge regions, which can be configured as frames, plates, or arcs covering specific areas of the wafers, made from materials like ceramic, porcelain, or metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma deposition is performed in PECVD boats, then coating is deposited on wafers, but excessively thick deposits are formed at edge regions of wafer holders and boat plates, preventing homogeneous distribution
Solution Approach 1:
The patent applies local quality by creating different plasma deposition conditions in different regions of the wafer. Attenuation elements are strategically positioned to reduce plasma intensity specifically at edge regions where excessive deposition occurs, while maintaining normal plasma conditions at the wafer center. This results in spatially varying deposition rates that compensate for the edge effect, achieving uniform coating thickness across the entire wafer surface.
Solution Approach 2:
The patent introduces attenuation elements as intermediary components between the plasma source and the wafer surface. These elements act as mediators that selectively absorb or scatter plasma particles, reducing the plasma flux reaching the edge regions of the wafer. The attenuation elements are positioned in the plasma path and configured to provide controlled attenuation, thereby preventing excessive material deposition at problematic locations without affecting the overall deposition process.
2Manufacturing precision
If attenuation elements are added to regulate plasma deposition, then coating uniformity is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the attenuation function into multiple discrete attenuation elements rather than using a single complex component. Each attenuation element is a simple structure positioned at specific locations where plasma attenuation is needed. This segmented approach allows for localized control of plasma deposition with simple, modular components that can be easily installed and adjusted, minimizing overall device complexity while achieving the desired coating uniformity.
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 solution ensures a uniform coating over the wafer area with a constant layer thickness without significantly affecting heating and homogenization times, thereby preventing excessive material deposition in edge regions.
Implementation Method 1
a plasma can be formed between the wafers located in the plasma boat during the plasma deposition when an electrical potential is applied
Implementation Method 2
attenuation elements are in each case arranged between neighboring boat plates and are electrically insulated from them... partial attenuation of the plasma deposition in the edge region is achieved
Data Source
AI summary
A plasma boat for receiving wafers with partial damping of the plasma deposition comprises a number of boat plates spaced apart in parallel, which are provided with wafer holders for receiving upright wafers, in order to securely hold the wafers during transport and during the depositing process in a coating chamber, and wherein the boat plates are mechanically connected to one another by electrically insulating spacers. This provides a plasma boat, with regulated plasma deposition, which ensures a deposition on wafers that is uniform over the surface area thereof and has a constant layer thickness. This is achieved by a damping element (12) being respectively arranged between the wafer holders (16) located parallel to one another, between adjacent boat plates (15), and electrically insulated with respect to the latter on spacer elements (2).