Edge-Zone Plasma Sheath Tuning for Uniform Wafer Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Plasma etching processes in semiconductor manufacturing face challenges in maintaining uniformity across a wafer, leading to improperly formed integrated circuit features and potential scrap wafers due to variations in the plasma sheath at the wafer edges.
Innovation Solution
A supplemental electric field is applied at the edge of the wafer and the focus ring to compensate for variations in the plasma sheath, ensuring a uniform plasma etching process across the entire wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If plasma etching is used to define small features in integrated circuits, then feature size reduction is achieved, but uniformity across the wafer deteriorates
Solution Approach 1:
The patent applies different electric field conditions to different regions of the wafer by positioning electrodes at specific locations (edge zone and center zone). The edge zone electrode receives a first voltage while the center zone electrode receives a second voltage, creating locally optimized plasma sheath characteristics for each region to compensate for edge effects and improve overall uniformity.
Solution Approach 2:
The patent changes the electrical parameters (voltage) applied to different zones of the plasma etching chamber. By adjusting the voltage at the edge zone electrode relative to the center zone electrode, the plasma sheath thickness and electric field distribution are modified to achieve uniform etching across the wafer surface.
2Device complexity
If conventional plasma etching is used, then etching process is simple, but plasma sheath uniformity deteriorates at wafer edges
Solution Approach 1:
The patent divides the plasma etching chamber into distinct zones with separate electrode control. The edge zone and center zone are segmented with independent voltage control, allowing separate optimization of plasma sheath characteristics in each region to achieve overall uniformity.
Solution Approach 2:
The patent introduces an edge zone electrode as an intermediary element between the plasma source and the wafer edge. This additional electrode mediates the electric field distribution at the wafer periphery, compensating for natural edge effects and improving plasma sheath 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
The implementation of a supplemental electric field results in a uniform plasma sheath, leading to properly aligned and functioning integrated circuit features across the wafer, thereby improving wafer yields and reducing scrap.
Implementation Method 1
A plasma is generated by applying a voltage between a bottom electrode embedded in the wafer support and a top electrode positioned above the wafer
Implementation Method 2
The supplemental electric field adjusts the plasma sheath above the edge of the wafer and the focus ring
Data Source
AI summary
A plasma etching system generates a plasma above a wafer in a plasma etching chamber. The wafer is surrounded by a focus ring. The plasma etching system straightens a plasma sheath above the focus ring by generating a supplemental electric field above the focus ring.