Wafer Layer Property Extraction Using Separated EM Pulses
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Solution Overview
Problem
Existing methods for measuring the properties of a wafer layer are inaccurate due to the influence of the electrical structure, leading to incorrect measurements of surface resistance.
Innovation Solution
A non-contact method using electromagnetic waves is employed to emit and detect waves passing through and reflected from the wafer layer, separating pulses to obtain transmission coefficients and exclude the influence of the wafer's electrical structure, allowing for accurate extraction of layer properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electromagnetic waves are used to measure layer properties through the wafer, then non-contact measurement is achieved, but measurement precision deteriorates due to interference from the wafer's electrical structure
Solution Approach 1:
The patent segments the measured signal into multiple pulses corresponding to different physical paths (direct transmission through wafer, reflection from layer, multiple bounces). By separating and analyzing each pulse individually, the system can isolate the layer's contribution from the wafer's electrical structure interference, thereby maintaining non-contact measurement while improving precision.
Solution Approach 2:
The patent extracts the specific signal component corresponding to the layer's reflection from the total electromagnetic signal by identifying and isolating the second pulse (which represents reflection from the layer interface). This extraction process removes the interfering components from the wafer's electrical structure, enabling accurate layer property measurement despite non-contact measurement constraints.
2Device complexity
If the wafer is used as a reference signal for measurement, then measurement process is simplified, but measurement precision deteriorates due to electrical structure interference
Solution Approach 1:
The patent introduces an intermediary approach by using the wafer's transmission signal as a reference only for calibration purposes, not for direct measurement. The actual layer property measurement is performed by analyzing the reflected signal from the layer itself, which is less affected by the wafer's electrical structure. This intermediary method reduces complexity compared to eliminating the wafer entirely while maintaining measurement 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
Accurately measures the properties of the wafer layer by excluding the influence of the wafer's electrical structure, providing precise data on surface resistance without using the wafer as a reference signal.
Implementation Method 1
emitting electromagnetic waves to a lower surface of the wafer, detecting a first electromagnetic wave, that passes through a target layer on an upper surface of the wafer
Implementation Method 2
detecting a second electromagnetic wave, that is reflected from the target layer, among the electromagnetic waves
Data Source
AI summary
Provided is a method of extracting properties of a layer on a wafer, the method including emitting electromagnetic waves to a lower surface of the wafer, detecting a first electromagnetic wave, that passes through a target layer on an upper surface of the wafer, and a second electromagnetic wave, that is reflected from the target layer, among the electromagnetic waves to obtain data including information about the first electromagnetic wave and the second electromagnetic wave, and separating a first pulse of the first electromagnetic wave and a second pulse of the second electromagnetic wave from each other in the data and obtaining property data of the target layer.