Piezoelectric Focus Ring Control for Uniform Wafer Edge Etching
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Solution Overview
Problem
The challenge of non-uniformity in semiconductor device fabrication due to wafer edge etching profile tilt and material loss of focus rings in plasma operations, leading to reduced yield and increased labor and time consumption in replacing focus rings.
Innovation Solution
A plasma operation apparatus with a focus ring and actuator system that maintains consistent distances and adjusts to compensate for material loss, using piezoelectric actuators to control the focus ring's position and gap height, ensuring uniform plasma distribution and reducing edge tilt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focus ring is used in plasma etching operation, then etching uniformity is improved, but material loss of the focus ring occurs leading to reduced lifespan and increased replacement frequency
Solution Approach 1:
The patent implements a dynamic adjustment mechanism where the focus ring's position and gap height are continuously or periodically adjusted during plasma etching operations. This dynamic compensation counteracts material loss by maintaining optimal spacing between the focus ring, wafer, and gas distribution plate, thereby extending the focus ring's usable lifespan while preserving etching uniformity
Solution Approach 2:
The system changes physical parameters such as the gap height between the focus ring and wafer, and the distance between the gas distribution plate and focus ring, during the etching process. By adjusting these parameters in response to material loss, the system maintains plasma distribution uniformity without requiring frequent focus ring replacement
2Manufacturing precision
If the distance between gas distribution plate and focus ring is not controlled, then plasma distribution uniformity deteriorates causing wafer edge tilt, but maintaining precise distance requires complex positioning systems
Solution Approach 1:
The focus ring structure incorporates self-aligning features and mechanical constraints that automatically maintain proper spacing with the gas distribution plate and wafer. The design includes integrated positioning elements such as protrusions fitting into recesses, or mechanical stops that prevent excessive movement, enabling the system to self-regulate distances without complex external positioning mechanisms
Solution Approach 2:
The system creates a mechanically stable configuration where the focus ring, gas distribution plate, and wafer are positioned in a balanced arrangement. By designing the support structure to provide uniform mechanical support and constraint, the system maintains consistent spacing without requiring active control or complex positioning systems
3Manufacturing precision
If focus rings are replaced frequently due to material loss, then plasma operation quality is maintained, but labor and time consumption increase
Solution Approach 1:
The system performs preliminary adjustments to the focus ring position and gap height before material loss significantly impacts performance. By proactively compensating for expected material loss through pre-programmed adjustment schedules or predictive monitoring, the system extends the interval between replacements and reduces urgent maintenance interruptions
Solution Approach 2:
The system incorporates monitoring mechanisms that detect focus ring material loss and trigger automatic or semi-automatic adjustment commands. This feedback loop allows the system to respond to actual wear conditions in real-time, optimizing the replacement schedule and reducing both unnecessary replacements and critical failures that would require immediate attention
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
Enhances the uniformity of plasma operations, extends focus ring life, and reduces time and labor costs by minimizing wafer edge etching profile tilt and maintaining consistent plasma distribution.
Implementation Method 1
using piezoelectric actuators to control the focus ring's position and gap height
Implementation Method 2
performing plasma etch on a surface of the wafer
Data Source
AI summary
The present disclosure provides a method for fabricating a semiconductor structure, including placing a wafer on a chuck, wherein the wafer is surrounded by a focus ring, the focus ring is supported by a first actuator, wherein the first actuator is in a cavity defined by the chuck and the edge ring, wherein the first actuator includes an outer ring disposed in the cavity, a piezoelectric layer apart from a top surface of the cavity, wherein an edge of the piezoelectric layer is fixed by the outer ring, and an inner ring disposed in the chamber at a center portion of the piezoelectric layer, performing plasma etch on a surface of the wafer, and controlling a distance between a gas distribution plate and a top surface of the focus ring to be less than a threshold value by the first actuator.