Edge Ring Lift Control for Wafer Edge Deposition Uniformity
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Solution Overview
Problem
Current semiconductor substrate processing technologies, particularly PECVD and ALD, face challenges in achieving uniform deposition profiles due to azimuthal nonuniformities and edge drop effects, with traditional configurations failing to provide optimal flow profiles and material conditions near the wafer edge, leading to inefficiencies and the need for manual adjustments of carrier/focus rings which are not feasible in automated systems.
Innovation Solution
The implementation of dynamic sheath control (DSC) through a pedestal assembly that allows for the lifting and tilting of edge rings to modulate the relative capacitance of RF fields, enabling recipe-controlled tuning of deposition profiles near the wafer edge, thereby improving film uniformity without requiring chamber modifications or complex automation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a standard pedestal configuration is used, then the device complexity is low, but the manufacturing precision of deposition profile near wafer edge deteriorates
Solution Approach 1:
The patent implements dynamic sheath control by making the edge ring movable rather than fixed. The ring can be lifted and tilted independently through actuation mechanisms, allowing real-time adjustment of the plasma sheath structure near the wafer edge. This dynamic capability enables optimization of deposition profiles without requiring complex fixed structural modifications.
Solution Approach 2:
The pedestal system is segmented into independent controllable components: the central pedestal, the edge ring, and the actuation mechanisms. The edge ring can be independently positioned and tilted relative to the pedestal, allowing localized control of plasma conditions at the wafer edge without affecting the entire pedestal structure.
2Manufacturing precision
If carrier/focus rings are manually replaced to optimize edge profiles, then the manufacturing precision improves, but the loss of time increases
Solution Approach 1:
Instead of replacing rings manually, the system uses dynamically actuated mechanisms to adjust ring position and orientation in real-time. Motors or other actuators enable the edge ring to be lifted and tilted during operation, providing continuous optimization capability without chamber interruption.
Solution Approach 2:
The system performs self-adjustment of deposition profiles through automated actuation mechanisms. The control system can independently modify ring positions based on process requirements without requiring external manual intervention or chamber opening, enabling the system to service itself.
3Adaptability or versatility
If a single carrier/focus ring is used, then the device complexity is low, but the adaptability to different deposition films deteriorates
Solution Approach 1:
The single ring design achieves versatility through dynamic positioning capabilities. By adjusting the ring's vertical position and tilt angle, the same physical ring can optimize plasma conditions for different film types and deposition recipes, replacing the need for multiple specialized rings.
Solution Approach 2:
The system changes operational parameters (ring height, tilt angle, position) rather than physical components to adapt to different deposition requirements. These parameter adjustments allow one ring to serve multiple functions across different film deposition processes.
4Manufacturing precision
If the edge ring is dynamically adjusted, then the manufacturing precision of deposition profile improves, but the device complexity increases
Solution Approach 1:
The complexity is managed by segmenting the adjustment functionality into focused components: lift mechanisms for vertical positioning and tilt mechanisms for angular adjustment. Each segment handles a specific degree of freedom, making the control system more manageable than a fully complex multi-axis system.
Solution Approach 2:
The edge ring serves multiple functions: it defines the plasma sheath boundary, controls material flow near the wafer edge, and can be independently positioned and tilted. This multi-functionality reduces the need for separate components, offsetting the added complexity with functional consolidation.
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 enhances film uniformity by dynamically adjusting the edge ring position to optimize deposition profiles, extending the usable wafer area and increasing the number of dies per wafer, while being cost-effective and retrofittable without the need for extensive automation or chamber modifications.
Implementation Method 1
modulate the relative capacitance that the RF field sees between the wafer or through the edge ring
Implementation Method 2
modulate the relative capacitance that the RF field sees
Data Source
Figure 1
Figure 2~3
Figure 4A
AI summary
A pedestal assembly including a pedestal for supporting a substrate. A central shaft positions the pedestal at a height during operation. A ring is placed along a periphery of the pedestal. A ring adjuster subassembly includes an adjuster flange disposed around a middle section of the central shaft. The subassembly includes a sleeve connected to the adjuster flange and extending from the adjuster flange to an adjuster plate disposed under the pedestal. The subassembly includes ring adjuster pins connected to the adjuster plate and extending vertically from the adjuster plate. Each of the ring adjuster pins being positioned on the adjuster plate at locations adjacent to and outside of a pedestal diameter. The ring adjuster pins contacting an edge undersurface of the ring. The adjuster flange coupled to at least three adjuster actuators for defining an elevation and tilt of the ring relative to a top surface of the pedestal.