Optical Emission Spectroscopy Light Collection for Plasma Uniformity
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Solution Overview
Problem
Existing optical emission spectroscopy technologies for plasma processing chambers have limitations in measuring plasma states uniformly across the entire substrate, particularly for larger wafers, as they can only analyze a portion of the plasma that influences the wafer, leading to incomplete data and potential contamination or damage of probes.
Innovation Solution
An apparatus for optical emission spectroscopy that includes a light collection unit with a concave lens to expand the light incident angle range, allowing for the collection and analysis of plasma states from the central to the outermost portion of the substrate, using a light transmission unit and analysis unit to provide accurate and adaptive measurements for substrates of various sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal probe is inserted into the chamber to measure plasma density using a Langmuir probe, then plasma characteristics such as electron density can be determined, but the probe may be contaminated or damaged by the plasma atmosphere and foreign substances may be introduced into the chamber
Solution Approach 1:
The patent replaces the mechanical contact-type Langmuir probe with an optical emission spectroscopy system that uses light to measure plasma characteristics. The system collects light emitted by plasma through optical fibers and analyzes spectral lines to determine electron density, eliminating mechanical contact between the measurement device and plasma, thus avoiding probe contamination and damage while maintaining measurement precision
2Device complexity
If an optical fiber is limited to an incident angle range of about 30° to about 40° for optical emission spectroscopy, then the apparatus structure is simple, but only a portion of the plasma (about 40% area) can be measured instead of the entire plasma state
Solution Approach 1:
The patent transitions from a single-point measurement approach to a multi-dimensional measurement approach by arranging multiple optical fibers at different spatial positions and angles around the plasma chamber. This allows simultaneous collection of light from various plasma regions, expanding measurement coverage from a limited 40% area to comprehensive plasma state monitoring while maintaining manageable system complexity through modular fiber arrangement
3Device complexity
If the light collection unit uses a narrow incident angle range, then the device structure is simpler, but the plasma state cannot be uniformly analyzed from central portion to outermost portion of the substrate
Solution Approach 1:
The patent divides the light collection function into multiple segments by using several optical fibers positioned at different locations and angles around the plasma chamber. Each fiber collects light from a specific angular range, and the combined data from all segments provides uniform coverage across the entire substrate area from center to outermost portions, achieving comprehensive plasma analysis without requiring each individual fiber to have a wide incident angle
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
Enables uniform and accurate analysis of plasma states across the entire substrate, improving analysis performance and reducing wafer scrap by allowing for real-time monitoring and minimizing probe contamination, while being adaptable to different substrate sizes and shapes.
Implementation Method 1
a light collection part configured to concentrate the light generated in the plasma process chamber and provide the concentrated light to the light transmission unit
Implementation Method 2
a light transmission unit configured to transmit the collected light
Implementation Method 3
an analysis unit configured to analyze the light provided through the light transmission unit, thereby analyzing a plasma state
Data Source
AI summary
Provided is an apparatus for optical emission spectroscopy. The apparatus for the optical emission spectroscopy includes a light collection unit configured to collect light within a plasma process chamber in which plasma is generated to process a substrate, a light transmission unit configured to transmit the collected light, and an analysis unit configured to analyze the light provided through the light transmission unit, thereby analyzing a plasma state. The light collection unit includes a light collection part configured to concentrate the light generated in the plasma process chamber and provide the concentrated light to the light transmission unit.