Plasma Processing Apparatus Multi-Wavelength Interference Thickness Detection
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Solution Overview
Problem
Existing plasma processing techniques face challenges in accurately detecting the remaining thickness of layers during etching, especially when undercoating layers with varying thicknesses and mask materials are involved, leading to inaccuracies in determining the etching depth and yield in semiconductor fabrication.
Innovation Solution
A plasma processing method that calculates the etching amount by comparing real pattern data with pre-recorded data from interference light intensity patterns of wafers with different undercoating layer thicknesses, allowing for precise detection of remaining layer thickness and etching depth, while considering the influence of undercoating and mask layers, and feeds this information back into the CVD process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interference light intensity is detected to measure remaining layer thickness, then etching depth detection is enabled, but measurement precision deteriorates when undercoating layer thickness varies
Solution Approach 1:
The invention transitions from single-wavelength detection to multi-wavelength detection, adding the wavelength dimension to the measurement system. By detecting interference light at multiple wavelengths simultaneously, the system can distinguish between variations caused by undercoating layer thickness and those caused by remaining layer thickness, thereby maintaining measurement precision regardless of undercoating variations.
Solution Approach 2:
The invention changes the detection parameter from single-wavelength intensity to multi-wavelength spectral distribution. By analyzing how interference patterns vary across different wavelengths, the system can extract accurate remaining layer thickness information even when undercoating layer thickness varies, as each wavelength provides complementary measurement data.
2Quantity of substance
If mask layer influence is included in interference light detection, then comprehensive layer information is obtained, but measurement precision of etching depth deteriorates
Solution Approach 1:
The invention segments the interference light signal into distinct components corresponding to different layer interfaces. By analyzing the spectral characteristics at multiple wavelengths, the system can separate the interference patterns generated by the mask layer from those generated by the etched layer, allowing independent measurement of each layer's thickness and improving etching depth precision.
Solution Approach 2:
The multi-wavelength detection system acts as an intermediary that processes the combined interference signals from multiple layers. By using wavelength as a distinguishing parameter, the system can identify and isolate the specific interference pattern corresponding to the etched layer, filtering out the influence of the mask layer while still obtaining comprehensive information about all layers.
3Reliability
If multiple wavelengths are detected to account for undercoating variations, then measurement reliability improves, but device complexity increases
Solution Approach 1:
The invention designs a multi-wavelength detection system that serves multiple functions simultaneously: it measures remaining layer thickness, characterizes undercoating layer thickness, and compensates for variations in both. This universal approach allows a single detection system to handle diverse measurement requirements without needing separate specialized devices for each measurement type.
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 method enables accurate detection of remaining layer thickness and etching depth, improving processing yield and reproducibility, even with scattered undercoating layer thicknesses and mask layer influences, and allows for precise management of undercoating and mask layer thicknesses in semiconductor production.
Implementation Method 1
the strength of the specific wavelength in emitted light of the formed plasma is changed with the etching progress of the layer to be processed
Implementation Method 2
the thickness of the remaining layer is detected using change in the intensity of interfered light (interference light) by utilizing the fact that light from the surface of a wafer containing the layer to be processed forms the interfered waveform
Data Source
AI summary
A plasma processing method of processing layer structure previously formed on an upper surface of a wafer disposed in a processing chamber within a vacuum container and having a layer to be processed and an undercoating layer disposed under the layer by plasma in the processing chamber, includes a step of calculating an etching amount of the layer to be processed at time during processing of any wafer by using result of comparing real pattern data with detection pattern data obtained by combining two patterns of intensity having as parameter wavelength of interference light obtained by processing the layer structure containing three or more undercoating layers having different thickness and the layer to be processed in advance of the processing of the any wafer and a real pattern of intensity having as parameter the wavelength of the interference light obtained during processing of the layer structure on the any wafer.