Focus Ring Ion Direction Control in Plasma Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In plasma processing for electronic device manufacturing, the consumption of focus rings leads to changes in the shape of the sheath, causing ions to be incident on the substrate edge in a non-vertical direction, resulting in deteriorated in-plane uniformity, which requires precise control of ion direction.
Innovation Solution
A plasma processing method involving setting the position of the focus ring's upper surface lower than the substrate's surface and applying a negative DC voltage to control the ion incident direction, allowing for adjustment between inwardly and outwardly inclined directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the focus ring is used to ensure in-plane uniformity of plasma processing, then the in-plane uniformity is improved, but the focus ring is consumed and its thickness decreases, leading to changes in sheath shape and deterioration of in-plane uniformity
Solution Approach 1:
The patent applies a negative DC voltage to the focus ring to change the electrical parameter, which modifies the sheath shape and ion incident direction to compensate for the physical wear of the focus ring, thereby maintaining in-plane uniformity throughout the focus ring's service life
Solution Approach 2:
The system uses feedback control by monitoring the focus ring thickness and adjusting the negative DC voltage accordingly, where the voltage magnitude is increased as the focus ring wears to maintain consistent plasma processing uniformity
2Device complexity
If ions are made to be vertically incident on the substrate edge, then the sheath shape is simplified, but this does not accommodate mask openings that require inclined ion incidence to form vertically extending openings
Solution Approach 1:
The patent makes the ion incident direction dynamically adjustable by applying variable negative DC voltage to the focus ring, allowing the system to adapt between vertical and inclined ion incidence depending on the mask opening requirements
Solution Approach 2:
By changing the electrical parameter (negative DC voltage) applied to the focus ring, the system can control the ion incident direction to achieve different sheath shapes, enabling both vertical and inclined ion incidence modes as needed
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 method effectively controls the ion incident direction on the substrate edge, maintaining in-plane uniformity and enabling the formation of desired openings during plasma etching by adjusting the negative DC voltage applied to the focus ring.
Implementation Method 1
applying a negative DC voltage to the focus ring... control the incident direction of the ions on the edge region of the substrate
Implementation Method 2
generating plasma in the chamber to perform plasma processing on the substrate
Data Source
AI summary
In a plasma processing method, a position in height direction of an upper surface of a focus ring surrounding an edge of a substrate mounted on a supporting table in a chamber of a plasma processing apparatus is set such that the position in height direction of the upper surface of the focus ring mounted on a mounting region of the supporting table is lower than a reference position that is a position in a height direction of an upper surface of the substrate. Plasma is generated in the chamber to perform plasma processing on the substrate in a state where the position in the height direction of the upper surface of the focus ring is maintained. A negative DC voltage is applied to the focus ring in a state where the position in height direction of the upper surface of the focus ring is maintained during the plasma generation.