Self-Heated Exhaust Sensor Tube for In Situ EPI Growth Monitoring
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Solution Overview
Problem
Existing methods for measuring film thickness in semiconductor processing chambers are inefficient and inaccurate, often requiring offline measurements that can lead to substrate rejection and reduced throughput due to interference from processing equipment.
Innovation Solution
The development of in situ growth rate sensors and exhaust assemblies within the processing chamber, equipped with optically transparent windows, silicon-containing coupons, and resistive heating elements, allows for real-time monitoring of film growth by simulating the epitaxial film growth on a substrate and reducing interference from processing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offline film thickness measurements are used, then measurement can be conducted without interference from processing equipment, but measurement efficiency decreases and substrate rejection increases
Solution Approach 1:
The sensor coupon is positioned in the exhaust system to receive film deposits during the epitaxial process, enabling preliminary measurement preparation without interfering with the main substrate processing. This allows measurement data to be ready before substrates leave the chamber, maintaining throughput while enabling accurate measurement.
Solution Approach 2:
A separate sensor coupon acts as an intermediary target for film deposition, receiving the same process conditions as substrates but serving as a dedicated measurement sample. This mediator allows accurate film thickness measurement without requiring direct measurement on production substrates, resolving the conflict between measurement accuracy and production efficiency.
2Productivity
If in situ film thickness measurements are conducted during processing, then measurement efficiency improves, but measurement accuracy decreases due to interference from processing equipment
Solution Approach 1:
The measurement function is segmented from substrate processing by using a separate sensor coupon in the exhaust system. This segmentation allows the measurement target to be spatially separated from interfering processing equipment like infrared lamps, enabling accurate in situ measurement without equipment interference.
Solution Approach 2:
The measurement target (sensor coupon) is extracted from the main substrate processing area and placed in the exhaust system where it is less exposed to interfering radiation from processing equipment. This extraction maintains the benefits of in situ measurement while reducing measurement errors from equipment interference.
3Manufacturing precision
If substrates are rejected based on offline measurements, then measurement specifications are enforced, but manufacturing efficiency decreases due to repeated processing iterations
Solution Approach 1:
The sensor coupon provides real-time feedback on film thickness during the epitaxial process, allowing process parameters to be adjusted while the process is running. This feedback mechanism ensures specification compliance without requiring multiple processing iterations, reducing time loss while maintaining manufacturing precision.
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 solution enables precise, real-time monitoring of film growth and thickness within the processing chamber, improving measurement accuracy, reducing substrate rejection, and enhancing processing throughput.
Implementation Method 1
a resistive heating element disposed within the body and adjacent to the optically transparent window
Implementation Method 2
monitoring an intensity of radiation reflected by or transmitted through a growth rate sensor
Implementation Method 3
an optically transparent window disposed at an end of the body
Implementation Method 4
epitaxy is a deposition process that grows a thin, ultra-pure layer, usually of silicon or germanium on a surface of a substrate
Implementation Method 5
thermally decomposing the process gas to deposit a material from the process gas onto the substrate surface
Data Source
AI summary
A method and apparatus for determining a growth rate on a semiconductor substrate is described herein. The apparatus is an optical sensor, such as an optical growth rate sensor. The optical sensor is positioned in an exhaust of a deposition chamber. The optical sensor is self-heated using one or more internal heating elements, such as a resistive heating element. The internal heating elements are configured to heat a sensor coupon. A film is formed on the sensor coupon by exhaust gases flowed through the exhaust and is correlated to film growth on a substrate within a process volume of the deposition chamber.