Film Thickness Measuring Apparatus Dynamic Optical Path Selection
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Solution Overview
Problem
Existing film-thickness measuring apparatuses in semiconductor manufacturing lack the ability to dynamically adjust the size of the measuring region, which can lead to inaccuracies in film thickness measurement depending on the type of structure or film on the wafer surface.
Innovation Solution
A film-thickness measuring apparatus that includes an optical-path selecting mechanism, allowing for the adjustment of the light-receiving region by optically connecting or disconnecting the second light-receiving fiber to either the spectrometer or the light source, enabling the selection of an appropriate measuring region based on the type of structure on the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed film-thickness measuring region is used, then the device complexity is reduced, but the measurement precision deteriorates when different wafer structures require different measuring region sizes
Solution Approach 1:
The patent implements a dynamic optical path selection mechanism that allows the measuring region size to be changed during operation. The optical path selecting mechanism can switch between connecting the second light-receiving fiber to the light source or to the spectrometer, enabling the system to adapt the measuring region size according to different wafer structures and measurement requirements, thereby resolving the contradiction between fixed complexity and variable precision needs
Solution Approach 2:
The patent divides the light-receiving function into multiple fibers: a first light-receiving fiber with a larger measuring region and a second light-receiving fiber with a smaller measuring region. By providing separate optical paths for each fiber and using an optical path selecting mechanism to switch between them, the system can select the appropriate measuring region size based on the specific measurement task, achieving both precision and manageable complexity through functional segmentation
2Adaptability or versatility
If a narrow film-thickness measuring region is used, then the adaptability to specific structures is improved, but the manufacturing precision deteriorates due to increased variation between regions
Solution Approach 1:
The dynamic optical path selection mechanism enables the system to switch between narrow and wide measuring regions based on the specific measurement requirements. When monitoring a particular structure like a memory cell, the system can select the narrow region (second light-receiving fiber) for high adaptability. When assessing overall wafer uniformity, it can switch to the wide region (first light-receiving fiber) to capture variation across the entire surface, thus resolving the contradiction between adaptability and manufacturing precision
3Manufacturing precision
If a wide film-thickness measuring region is used, then the manufacturing precision is improved by reducing regional variation, but the adaptability to specific structures deteriorates due to inclusion of unwanted information
Solution Approach 1:
The optical path selecting mechanism provides dynamic control over the measuring region size. For assessing overall manufacturing precision and film thickness uniformity, the system can activate the wide measuring region (first light-receiving fiber) to capture data across the entire wafer surface. When the task requires focusing on specific structures and eliminating unwanted regional information, the system switches to the narrow measuring region (second light-receiving fiber), thus resolving the contradiction between manufacturing precision and adaptability
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 film thickness measurement by allowing the apparatus to adapt the size of the measuring region to the specific structure on the wafer, improving measurement precision and reliability.
Implementation Method 1
a spectrometer configured to decompose reflected light from a wafer in accordance with wavelength and measure an intensity of the reflected light at each of wavelengths
Implementation Method 2
an illuminating fiber coupled to the light source and having a distal end disposed at a predetermined position in a wafer supporting structure... a first light-receiving fiber having a distal end disposed at the predetermined position... a second light-receiving fiber having a distal end which is disposed at the predetermined position
Data Source
AI summary
A film-thickness measuring apparatus includes: a light source; an illuminating fiber coupled to the light source and having a distal end disposed at a predetermined position in a wafer supporting structure; a spectrometer configured to decompose reflected light from a wafer in accordance with wavelength and measure an intensity of the reflected light at each of wavelengths; a first light-receiving fiber having a distal end disposed at the predetermined position; a second light-receiving fiber having a distal end which is disposed at the predetermined position and is adjacent to the distal end of the first light-receiving fiber; a processor configured to determine a film thickness of the wafer based on a spectral waveform indicating a relationship between the intensity of the reflected light and the wavelength; and an optical-path selecting mechanism configured to optically connect and disconnect the second light-receiving fiber and the spectrometer.