Plasma Etching with RF Cycling for Selective Recess Profiles
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Solution Overview
Problem
The challenge in silicon etching is achieving high selectivity and a rectangular shape at the bottom of recesses while minimizing processing time, as existing methods often result in tapered bottoms and require time-consuming gas switching, reducing throughput.
Innovation Solution
A substrate processing method involving a plasma processing apparatus that supplies a mixed gas containing Cl2 and O2, with alternating radio-frequency power conditions to generate first and second plasmas, allowing for controlled etching under different power and time settings, thereby improving selectivity and shape without gas switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas switching is performed to improve selectivity and shape control, then etching quality improves, but processing time increases and throughput decreases
Solution Approach 1:
The patent applies periodic action by alternating between two plasma generation conditions in cyclic manner. First plasma generation condition modifies the surface with halogen-containing radicals, then second plasma generation condition performs etching with oxygen-containing radicals. This periodic switching of plasma conditions within a single gas atmosphere achieves both high selectivity and fast processing speed, eliminating the need for time-consuming gas switching operations.
2Productivity
If conventional plasma etching is used to increase processing speed, then throughput improves, but selectivity and shape control deteriorate
Solution Approach 1:
The patent segments the plasma etching process into two distinct phases with different plasma generation conditions. The first phase uses halogen-containing gas to create a protective modified layer on the etching target film surface, while the second phase uses oxygen-containing gas to selectively etch through this modified layer. This segmentation allows each phase to optimize for its specific function, achieving both high speed and high selectivity simultaneously.
Solution Approach 2:
The patent changes plasma generation parameters between two conditions: first condition optimizes for surface modification with halogen radicals, second condition optimizes for etching with oxygen radicals. By dynamically changing plasma generation parameters rather than gas composition, the process achieves rapid transitions between functional states, maintaining high throughput while ensuring precise selectivity control.
3Productivity
If halogen-containing gas is used to improve etching speed, then processing efficiency improves, but selectivity deteriorates due to lack of protective layer formation
Solution Approach 1:
The patent applies preliminary action by first generating plasma under first generation conditions that create a protective modified layer on the etching target film surface using halogen-containing gas. This preliminary surface modification prepares the substrate for subsequent high-speed etching. Only after this protective layer is formed does the process switch to second plasma generation conditions for rapid oxygen-based etching, ensuring both selectivity and speed are achieved.
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 enables faster etching with improved selectivity and rectangular shape retention at the bottom of recesses, reducing processing time and maintaining high throughput by controlling plasma conditions to optimize etching without gas switching.
Implementation Method 1
performing plasma processing on the workpiece by first plasma generated from the process gas under first plasma generation conditions
Implementation Method 2
a condition of radio-frequency power and a processing time are different from those in the first plasma generation conditions
Data Source
AI summary
A substrate processing method in a substrate processing apparatus includes (a) supplying a process gas that contains a gas containing halogen other than fluorine and a gas containing oxygen, to a processing container in which a stage is disposed, the stage being configured to place thereon a workpiece having an etching target film, (b) performing plasma processing on the workpiece by first plasma generated from the process gas under first plasma generation conditions, (c) performing plasma processing on the workpiece by second plasma generated from the process gas under second plasma generation conditions in which a condition of radio-frequency power and a processing time are different from those in the first plasma generation conditions, and other conditions are the same, and (d) repeating (b) and (c).