CMP Vibration Monitoring for Real-Time Micro-Scratch Detection
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes in semiconductor manufacturing introduce mechanical defects like scratches due to polishing pads, and current methods require periodic optical inspections, leading to substantial downtime and reduced yield.
Innovation Solution
The implementation of vibration sensors to monitor CMP processes in real-time, analyzing characteristic vibrations to detect micro-scratch occurrences and automatically stop the process when severe scratches are detected, allowing for continuous operation and improved yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic optical observations are performed during CMP processes, then micro-scratch detection capability is improved, but process downtime increases and yield decreases
Solution Approach 1:
The patent replaces optical observation systems with acoustic emission sensing. Acoustic sensors detect micro-scratch events through sound waves generated during scratching, eliminating the need for periodic optical inspections that cause downtime. This substitution enables continuous monitoring without interrupting the CMP process, thereby maintaining both detection capability and productivity.
Solution Approach 2:
The acoustic emission monitoring system operates continuously throughout the CMP process, providing real-time detection of micro-scratch events. Unlike periodic optical observations that interrupt the process, the acoustic system maintains continuous operation, allowing immediate detection and response to scratches without stopping or slowing the polishing process, thus preserving yield.
2Measurement precision
If periodic optical observations are performed during CMP processes, then micro-scratch detection capability is improved, but process time increases
Solution Approach 1:
The patent replaces optical observation systems with acoustic emission sensing. Acoustic sensors detect micro-scratch events through sound waves generated during scratching, eliminating the need for periodic optical inspections that cause downtime. This substitution enables continuous monitoring without interrupting the CMP process, thereby maintaining both detection capability and productivity.
Solution Approach 2:
The acoustic emission monitoring system operates continuously throughout the CMP process, providing real-time detection of micro-scratch events. Unlike periodic optical observations that interrupt the process, the acoustic system maintains continuous operation, allowing immediate detection and response to scratches without stopping or slowing the polishing process, thus preserving yield.
3Productivity
If vibration sensors are used for real-time monitoring, then continuous process operation is improved, but device complexity increases
Solution Approach 1:
The patent uses acoustic emission sensors as intermediaries to detect micro-scratch events. These sensors convert mechanical scratching events into acoustic signals that can be processed electronically. This intermediary approach simplifies the monitoring system compared to complex optical inspection systems, while enabling continuous real-time detection without interrupting the CMP process.
Solution Approach 2:
The patent replaces complex optical observation systems with simpler acoustic emission sensing. The acoustic system uses straightforward sensors that detect sound waves from scratching events, requiring less complex infrastructure than optical systems while providing continuous monitoring capability that maintains productivity.
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 online monitoring and control of CMP processes, reducing downtime and costs, and increasing the speed and yield of semiconductor device manufacturing by promptly addressing micro-scratch issues.
Implementation Method 1
collecting, by a set of vibration sensors, a plurality of vibration signals generated during the CMP process
Implementation Method 2
detecting, by a signal processor, micro-scratch events based on the acoustic emission signals
Data Source
AI summary
An apparatus for monitoring a CMP process on a wafer includes vibration sensors to collect vibration data corresponding to the CMP process and to transmit electric signals, a signal processor to obtain digital signals by converting the electric signals into a frequency domain, and filters to filter out noise signals from the digital signals to obtain noise reduced digital signals. The signal processor obtains one or more frequency spectrums from the noise reduced digital signals, and determines a micro-scratch occurrence on the wafer by analyzing the obtained one or more frequency spectrums. The vibration sensors are in rigid contact with at least a tool such as a head holding a carrier of the wafer or a platen holding a polishing pad. Each vibration sensor includes at least two sub-frequency-ranges respectively corresponding to at least two materials to be polished by the polishing pad.