Swirl Side Gas Feed Plasma Chamber for Uniform ICP Etching
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Solution Overview
Problem
Existing plasma chambers with inductively coupled plasma (ICP) sources face challenges in maintaining a uniform etch rate due to the use of center gas feeds (CGF) with heavy molecules, which cause non-uniformity in the etching process.
Innovation Solution
A plasma chamber design incorporating swirl motion side gas feeds (SGF) that spray gas in a downward swirl motion, utilizing both first and second swirl motion SGFs along the chamber walls, along with a center gas feed, to improve etch rate uniformity and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a center gas feed (CGF) with heavy molecules is used in an ICP plasma chamber, then the etch rate is improved, but the uniformity of the etch rate is degraded
Solution Approach 1:
The gas feed system is segmented into multiple side gas feeds positioned at different locations around the chamber perimeter, each independently controlling gas flow to specific regions. This segmentation allows localized adjustment of gas distribution to compensate for the non-uniformity caused by heavy molecule CGF, maintaining both high etch rate and uniformity across the wafer surface.
Solution Approach 2:
Different regions of the chamber are provided with different gas flow characteristics through strategically positioned side gas feeds. The gas flow parameters (flow rate, pressure, timing) are locally optimized for each chamber region to compensate for variations in plasma distribution, ensuring uniform etch rate across the entire wafer while maintaining high productivity from the heavy molecule gas.
2Productivity
If ICP is used instead of CCP, then the etch rate is increased, but the selectivity and process repeatability are reduced
Solution Approach 1:
The system incorporates real-time monitoring of etch rate and plasma parameters with feedback control mechanisms that adjust gas flow rates and power levels to maintain consistent process conditions. This feedback loop compensates for the inherent variability of ICP, improving process repeatability while preserving the high etch rate advantage.
Solution Approach 2:
Multiple gas flow parameters (flow rates, pressures, timing sequences) are optimized and controlled to achieve consistent plasma conditions despite ICP's natural variability. By precisely controlling these parameters through the side gas feed system, the process achieves both high etch rate and improved repeatability.
3Productivity
If gas with heavy molecules is sprayed through a center gas feed, then the etch rate is improved, but the gas velocity in the z-direction increases causing non-uniform etch rate
Solution Approach 1:
The gas delivery function is segmented from the center feed to multiple peripheral side feeds, distributing the heavy molecule gas flow across different spatial locations. This segmentation reduces the concentration of gas velocity in the z-direction at any single location, preventing the formation of high-velocity jets that cause non-uniform etching, while still delivering sufficient gas for high etch rate.
Solution Approach 2:
The gas delivery approach transitions from a vertical (z-direction) center feed to a combination of horizontal (radial) side feeds with downward swirl motion. This dimensional change in gas delivery geometry distributes the gas flow more evenly across the chamber cross-section, reducing excessive z-direction velocity while maintaining effective gas delivery for high etch rate.
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 design maintains a uniform etch rate and improves etch rate consistency by using a combination of swirl motion SGFs and a center gas feed, enhancing the synergistic effect of ions and radicals in the etching process.
Implementation Method 1
a first swirl motion side gas feed provided on a side surface of the housing and configured to spray gas into the housing; a second swirl motion side gas feed provided on the side surface of the housing and configured to spray gas into the housing, wherein the first swirl motion side gas feed and the second swirl motion side gas feed spray gas along a wall surface of the housing
Implementation Method 2
Plasma is formed in a reaction space inside the plasma chamber, and the etching process for a semiconductor is performed using the plasma
Data Source
AI summary
A plasma chamber includes: a housing having a seating part on which a wafer is seated; a first swirl motion side gas feed that is provided on the side surface of the housing and injects gas into the housing; and a second swirl motion side gas feed that is provided on the side surface of the housing and injects gas into the housing, wherein the first swirl motion side gas feed and the second swirl motion side gas feed inject gas along the wall surface of the housing, the first swirl motion side gas feed injects gas on a plane extending in a direction parallel to a plane formed by the seating part, and the second swirl motion side gas feed injects gas while forming an angle with respect to the plane extending in the direction parallel to the plane formed by the seating part.