CMP Thickness Control via Spectroscopic Feedback
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Solution Overview
Problem
Current chemical mechanical planarization (CMP) methods lack precision in measuring and adjusting the thickness of materials on semiconductor wafers during polishing, leading to inaccuracies in surface smoothing and material removal.
Innovation Solution
A system that uses spectroscopic signals to measure the thickness of materials on semiconductor wafers before and after polishing, adjusting polishing parameters such as rotation speed, pressure, and slurry composition to achieve precise thickness control by comparing measured signals to a spectral library.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CMP methods are used without spectroscopic measurement, then the polishing process is simpler and faster, but the thickness measurement precision and material removal control accuracy deteriorate
Solution Approach 1:
The patent merges the spectroscopic measurement system with the CMP polishing system by integrating the optical path through the polishing pad. The emitter and detector are positioned to measure material thickness through the polishing pad during the polishing process, combining measurement and processing functions into a single integrated system.
Solution Approach 2:
The polishing pad serves as an intermediary medium that allows optical signals to pass through while maintaining contact between the polishing head and wafer. The pad transmits both mechanical polishing force and spectroscopic signals, enabling non-contact measurement through the polishing interface.
2Manufacturing precision
If material thickness is not measured during polishing, then the process is faster and requires less time, but the manufacturing precision of material thickness control deteriorates
Solution Approach 1:
The system implements real-time feedback by continuously measuring material thickness during polishing using spectroscopic signals. The measured thickness data is fed back to control the polishing process, allowing dynamic adjustment of polishing parameters to achieve precise thickness control while monitoring progress in real-time.
Solution Approach 2:
The system performs preliminary measurement of material thickness before polishing begins and during the process, allowing prediction of remaining thickness and optimization of polishing duration. This prevents over-polishing and reduces total process time by knowing when the target thickness is approaching.
3Measurement precision
If spectroscopic measurement is implemented during CMP, then thickness measurement accuracy improves, but the device complexity and measurement system requirements increase
Solution Approach 1:
The polishing pad acts as an optical intermediary that transmits spectroscopic signals from the emitter through the pad to the detector. This allows measurement without direct contact between the optical components and the wafer, simplifying the measurement system architecture while maintaining measurement capability through the polishing interface.
4Manufacturing precision
If real-time thickness measurement is performed during polishing, then material removal control precision improves, but the productivity and polishing speed may decrease
Solution Approach 1:
The spectroscopic measurement operates continuously during the polishing process without interrupting the mechanical polishing action. The optical measurement and mechanical polishing occur simultaneously, maintaining continuous useful action for both measurement and material removal without sequential delays.
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 approach increases the sensitivity and accuracy of CMP, allowing for more precise control over material removal and surface smoothing, improving the overall precision of semiconductor wafer fabrication.
Implementation Method 1
an emitter component configured to apply an optical signal to a first material of the semiconductor device and a detector component configured to detect an altered optical signal from the first material to generate a spectroscopic signal
Data Source
AI summary
One or more methods or systems for performing chemical mechanical planarization (CMP) are provided. The system includes at least one of an emitter, a detector, a spectroscopic signal generator, a comparator, a spectral library, a controller or a CMP device. A spectroscopic signal is generated and is used to determine the thickness of a first material formed on or from a wafer by comparing the spectroscopic signal to a spectral library. Responsive to the thickness not being equal to the desired thickness, the controller instructs the CMP device to perform a rotation to reduce the thickness of the first material. The system and method herein increase the sensitivity of the CMP, such that the thickness of the first material is reduced with greater accuracy and precision, as compared to where the thickness is not measured between consecutive rotations of a wafer.