Variable Condenser Edge Ring Control for Plasma Etching Uniformity
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Solution Overview
Problem
In plasma processing apparatuses, the edge ring is consumed during repeated wafer etching, leading to distortion of the electric field at the wafer's circumferential edge, causing non-uniform etching and patterning fluctuations due to the receding or deformation of the edge ring.
Innovation Solution
A plasma processing apparatus with a variable condenser disposed along the circumferential direction of the lower plate, featuring first and second capacitance elements on the inner and outer sides, respectively, allows for independent control of voltages to maintain a stable electric field at the edge ring, compensating for its deformation and ensuring uniform etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an edge ring is provided on the lower electrode to maintain perpendicular ion incidence at the wafer edge, then etching uniformity is improved, but the edge ring is consumed during repeated processing causing its upper surface to recede or deform
Solution Approach 1:
The patent applies the dynamics principle by making the edge ring movable rather than fixed. The edge ring is designed to move in the vertical direction along the lower electrode surface, allowing it to dynamically adjust its position. This movement compensates for the consumption and recession of the edge ring upper surface, maintaining the perpendicular ion incidence angle at the wafer edge throughout the edge ring's service life, thereby resolving the contradiction between etching uniformity and service life
Solution Approach 2:
The patent applies parameter changes by varying the vertical position of the edge ring along the lower electrode. As the edge ring consumes and its upper surface recedes, its vertical position parameter is adjusted to maintain the correct geometric relationship with the wafer edge. This parameter adjustment ensures that the ion incidence angle remains perpendicular, preserving etching uniformity while extending the effective service life of the edge ring
2Manufacturing precision
If the edge ring upper surface recedes or deforms due to ion collision, then the electric field at the wafer edge distorts, but providing a replacement edge ring increases processing time and reduces productivity
Solution Approach 1:
The patent applies self-service by enabling the edge ring to automatically compensate for its own consumption. The movable edge ring design allows it to self-adjust its vertical position in response to upper surface recession from ion collision. This self-compensation mechanism maintains electric field uniformity and pattern quality without requiring external intervention or replacement, thereby eliminating downtime and maintaining high wafer processing throughput
Solution Approach 2:
The dynamic movement capability of the edge ring allows it to continuously adapt to consumption effects during operation. By moving vertically along the lower electrode, the edge ring maintains optimal positioning despite upper surface recession, preventing electric field distortion and pattern uniformity degradation without requiring replacement, thus preserving productivity
3Manufacturing precision
If the edge ring is made replaceable to maintain etching quality, then pattern uniformity is preserved, but the complexity of the apparatus increases due to additional control mechanisms
Solution Approach 1:
The edge ring's self-service capability through automatic vertical movement eliminates the need for complex external control systems. The edge ring autonomously adjusts its position to compensate for consumption, maintaining etching rate uniformity without requiring sophisticated sensors, controllers, or actuation systems, thereby preserving apparatus simplicity
Solution Approach 2:
The patent introduces a simple vertical guide structure as an intermediary that facilitates edge ring movement along the lower electrode. This minimal intermediary mechanism enables the edge ring to adjust its position while maintaining electrical connection and geometric alignment, achieving precise control with minimal added 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
This solution maintains the perpendicular incidence of ions on the wafer surface, even at the edge, and enhances the uniformity of etching characteristics by dynamically adjusting the capacitance values based on the edge ring's deformation, thereby preventing pattern tilting and rate variations.
Implementation Method 1
a variable condenser (13) is provided along a circumferential direction of the lower plate (211) in a region having a circular ring configuration
Implementation Method 2
the gas that is introduced to the chamber is plasmatized on the wafer surface
Implementation Method 3
the ions inside the plasma are incident at an angle that is substantially perpendicular to the wafer surface
Data Source
AI summary
According to one embodiment, a plasma processing-apparatus processing object support platform includes a lower plate, an upper plate, and a variable condenser. The lower plate is electrically conductive. The upper plate is provided on the lower plate. A processing object is placed on an upper surface of the upper plate. The variable condenser is provided along a circumferential direction of the lower plate in a region at an upper outer circumferential vicinity of the lower plate. The region has an annular configuration. The variable condenser includes a first capacitance element and a second capacitance element disposed respectively on an inner circumferential side and an outer circumferential side in the region having the annular configuration. Mutually-different control voltages are suppliable to the first capacitance element and the second capacitance element.