Edge Ring DC Bias Control for Vertical Ion Incidence in Etching
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in maintaining vertical ion incidence angles during etching due to edge ring wear, which affects the uniformity and precision of plasma processing on semiconductor wafers, and conventional methods of adjusting RF power to correct this issue can impact heat input and process performance.
Innovation Solution
A plasma processing apparatus with a controller that adjusts the DC voltage and impedance of a variable passive element connected to the edge ring to control ion incidence angles, allowing precise tilt angle correction without affecting RF power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If RF power is adjusted to correct ion incidence angle tilt caused by edge ring wear, then ion incidence angle is improved, but heat input and process performance are adversely affected
Solution Approach 1:
The control system is segmented into independent components: DC voltage control for ion incidence angle correction and RF power control for process parameters. This allows the DC voltage to be adjusted independently to correct tilt without affecting RF power levels, thereby maintaining heat input and process performance while achieving precise ion incidence angle control
Solution Approach 2:
The edge ring serves multiple functions: it provides mechanical support, defines the processing region, and acts as an electrode for DC voltage application. By applying DC voltage to the edge ring, the system can correct ion incidence angle tilt without requiring separate adjustment mechanisms, enabling multi-functional control that avoids the trade-offs of conventional single-function approaches
2Manufacturing precision
If DC voltage is applied to correct ion incidence angle, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The edge ring is designed to serve multiple functions simultaneously: it provides mechanical support, defines the processing region, and acts as an electrode for DC voltage application. This multi-functionality reduces the need for additional components, thereby minimizing device complexity while achieving precise ion incidence angle control
Solution Approach 2:
The control system uses feedback from sensors to automatically adjust DC voltage and RF power parameters. This self-service capability allows the system to maintain optimal ion incidence angles without requiring complex manual intervention or additional control components, thereby improving precision while keeping device complexity manageable
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 solution effectively maintains vertical ion incidence angles during etching, ensuring uniform plasma processing on semiconductor wafers while minimizing impacts on heat input and process performance.
Implementation Method 1
a DC power supply configured to apply a negative DC voltage to the edge ring
Implementation Method 2
a source RF power supply configured to supply source RF power to the upper electrode or the lower electrode to generate plasma from a gas inside the plasma processing chamber
Implementation Method 3
a bias power supply configured to supply bias power to the lower electrode
Data Source
AI summary
A plasma processing apparatus is provided. The apparatus comprises: a plasma processing chamber; a substrate support arranged inside the plasma processing chamber, the substrate support including a lower electrode, an electrostatic chuck, and an edge ring disposed to surround a substrate mounted on the electrostatic chuck; an upper electrode arranged on an upper side of the substrate support; a source RF power supply configured to supply source RF power to generate plasma from a gas; a bias power supply configured to supply bias power; a DC power supply configured to apply a negative DC voltage; an RF filter electrically connected between the edge ring and the DC power supply, and including at least one variable passive element; and a controller configured to control the DC power supply and the variable passive element, and configured to control a voltage of the bias power within a permissible range.