Optical Absorption Sensing for Vacuum Boron Clean End Points
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Solution Overview
Problem
Current semiconductor processing systems lack effective methods for detecting boron-containing compounds, such as boron trifluoride, under vacuum or near vacuum conditions, leading to issues with under-cleaning or over-cleaning, which affects substrate contamination and process uniformity.
Innovation Solution
A semiconductor processing system incorporating a remote plasma unit and an optical absorption sensor configured to measure boron-containing compounds at low levels, using an elongate optical cell with an infrared detector and filter to detect boron trifluoride in the cleaning byproducts, allowing for precise end-point detection of the cleaning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection methods are used for boron-containing compounds, then the system can operate under vacuum conditions, but the detection precision is insufficient leading to under-cleaning or over-cleaning
Solution Approach 1:
The patent replaces conventional mechanical or electronic detection methods with an optical detection system. The optical absorption sensor uses light absorption characteristics of boron-containing compounds (specifically BF3) to detect their presence and concentration. This substitution enables precise detection under vacuum conditions where conventional methods fail, directly resolving the contradiction between measurement precision and cleaning control reliability.
Solution Approach 2:
The patent changes the detection parameter from electrical or mechanical signals to optical absorption signals. By measuring the absorption of light at specific wavelengths by boron-containing compounds, the system achieves high detection precision in vacuum environments. This parameter change allows accurate monitoring of cleaning progress, preventing both under-cleaning and over-cleaning.
2Manufacturing precision
If the cleaning process is monitored continuously, then the substrate processing uniformity improves, but the device complexity increases due to additional sensors and systems
Solution Approach 1:
The patent extracts only the essential detection function needed for monitoring boron-containing compounds during cleaning. The optical absorption sensor system is designed to perform this single function efficiently, avoiding the need for complex multi-functional sensor arrays. This extraction approach maintains substrate processing uniformity through continuous monitoring while minimizing device complexity.
Solution Approach 2:
The patent introduces an optical absorption sensor as an intermediary between the cleaning process and the control system. This intermediary provides continuous monitoring data without directly interfering with the cleaning process or requiring complex integration with existing chamber systems. The sensor acts as a simple, effective bridge that improves manufacturing precision while adding minimal complexity.
3Productivity
If the optical absorption sensor is installed downstream, then it does not interrupt the flow of processing fluids, but the measurement of boron-containing compounds becomes more difficult due to lower concentrations
Solution Approach 1:
The patent extends the optical detection path length in the downstream region where boron-containing compound concentrations are lower. By increasing the measurement dimension (path length), the sensor maintains sufficient absorption signal strength even at lower concentrations. This dimensional change allows continuous fluid flow without interruption while preserving detection precision through enhanced optical path integration.
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 accurate detection of boron-containing compounds at extremely low levels, preventing under-cleaning or over-cleaning, improving substrate processing uniformity and productivity by optimizing the cleaning process without interrupting the flow of processing fluids or gases.
Implementation Method 1
The optical absorption sensor may include an infrared detector and a light source disposed at opposing first end and second end of the elongate optical cell, respectively... light entering into the elongate optical cell through the optical window may include infrared radiation having a wavenumber ranging between about 400 cm−1 and about 3,000 cm−1
Implementation Method 2
The remote plasma unit may be configured to generate plasma effluents from a fluorine-containing precursor
Data Source
AI summary
Semiconductor processing systems and methods are disclosed. An exemplary semiconductor processing system may include a semiconductor processing chamber containing a solid boron deposit, a remote plasma unit disposed upstream of the semiconductor processing chamber, and an optical absorption sensor disposed downstream of the semiconductor processing chamber. The remote plasma unit may be configured to generate plasma effluents from a fluorine-containing precursor. The optical absorption sensor may be configured to measure within an outflow from the semiconductor processing chamber a level of a boron-containing compound produced via a reaction between at least a portion of the solid boron deposit and the plasma effluents flowed from the remote plasma unit into the semiconductor processing chamber.