Faraday Shield Plasma Control for Vertical Etch Profiles
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Solution Overview
Problem
In the semiconductor-device fabrication field, achieving a vertical etch profile for non-volatile materials is challenging due to the volatile properties of these materials, which cause reaction byproducts to adhere to the side-wall portion of the etch profile, leading to taper profiles and potential short-circuits between patterns.
Innovation Solution
A plasma processing apparatus with a dielectric window, induction antenna, and Faraday shield unit that employs capacitive coupling and time-modulation of radio-frequency powers to control the plasma distribution, allowing for the vertical implementation of the etch profile by adjusting the phase and voltage of radio-frequency powers applied to the Faraday shields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional inductive coupling plasma processing is used, then the apparatus configuration remains simple, but the etch profile becomes tapered due to reaction byproduct adhesion on side-walls
Solution Approach 1:
A Faraday shield is introduced as an intermediary component between the induction coil and the processing chamber. This shield mediates the plasma generation process by controlling electron heating and plasma distribution, enabling vertical etch profiles while maintaining inductive coupling configuration. The Faraday shield acts as a mediator that modifies the electromagnetic field interaction to achieve desired plasma characteristics without changing the fundamental inductive coupling approach.
Solution Approach 2:
The invention changes physical parameters by applying radio-frequency power to the Faraday shield, transforming it from a passive component to an active plasma control element. By adjusting the RF power parameters applied to the Faraday shield, the plasma distribution and ion incident angle can be controlled to achieve vertical etch profiles, thereby changing the plasma generation parameters without altering the apparatus configuration.
2Quantity of substance
If higher radio-frequency power is applied to increase plasma density, then plasma generation improves, but reaction byproducts adhere more to side-walls causing taper profiles
Solution Approach 1:
The Faraday shield creates local quality differences in plasma distribution by selectively controlling plasma generation in different regions. The shield structure with its specific geometry and RF power application creates zones of different plasma density and ion flux, enabling vertical side-wall etching while maintaining overall high plasma density for efficient processing.
Solution Approach 2:
By applying radio-frequency power to the Faraday shield, periodic oscillating electric fields are created that control plasma generation dynamically. This periodic action allows control over ion bombardment characteristics and plasma distribution, preventing byproduct adhesion while maintaining high plasma density through controlled plasma generation cycles.
3Device complexity
If a single Faraday shield is used, then the structure remains simple, but plasma distribution uniformity and etch profile control are insufficient
Solution Approach 1:
The Faraday shield is segmented into multiple independent sections that can be controlled separately. This segmentation allows different regions of the shield to be powered independently, enabling precise control over plasma distribution across the processing chamber. Each segment can be optimized for specific etching requirements, achieving uniform plasma distribution and vertical etch profiles through localized control.
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 approach enables the vertical etch profile by controlling the ion incident angle and plasma distribution, reducing sputtering efficiency loss and preventing taper profiles, thereby improving device characteristics by maintaining pattern integrity.
Implementation Method 1
plasma is generated from this process gas by causing a radio-frequency current to flow along an induction coil that is deployed outside the plasma processing chamber
Implementation Method 2
Faraday shield unit deployed between the induction antenna and the dielectric window and performing a capacitive coupling with the plasma
Implementation Method 3
control apparatus for controlling a first radio-frequency power source and a second radio-frequency power source, the first radio-frequency power source being used for supplying a radio-frequency power to the induction antenna, the second radio-frequency power source being used for supplying a radio-frequency power to the Faraday shield unit
Data Source
AI summary
In a plasma processing apparatus including a processing chamber, a dielectric window for hermetically sealing the upper portion of the processing chamber, an induction antenna deployed above the dielectric window, a Faraday shield unit, and a control apparatus for controlling a first radio-frequency power source for supplying a radio-frequency power to the induction antenna, and a second radio-frequency power source for supplying a radio-frequency power to the Faraday shield unit, the Faraday shield unit includes a first Faraday shield having a first element, and a second Faraday shield having a second element deployed at a position adjacent to the first element, the control apparatus applying a time modulation to the radio-frequency powers that are respectively supplied to the first element and the second element, the phase of the first-element-supplied and time-modulated radio-frequency power being different from the phase of the second-element-supplied and time-modulated radio-frequency power.