CMP Endpoint Detection via Light Absorption
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Solution Overview
Problem
Chemical-mechanical planarization (CMP) processes face challenges in accurately stopping at the end-point layer during wafer polishing, particularly due to the thin and nonplanar nature of the surface layer, leading to pattern loading effects and potential damage to underlying layers.
Innovation Solution
A CMP system incorporating a light source and detector to provide incident light with photon energy greater than the band gap energy of the end-point layer, allowing for absorption detection and precise control to stop the polishing process at the desired layer, preventing over-polishing and ensuring accurate removal of the planarization layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional CMP process is used to remove planarization layer, then material removal is achieved, but pattern loading effects occur and underlying layers may be damaged due to inability to precisely stop at end-point layer
Solution Approach 1:
The patent applies preliminary action by forming an oxidized surface layer on the work function layer before the CMP process. This oxidized layer serves as a sacrificial endpoint indicator that can be detected during polishing. The layer is prepared in advance with specific thickness and oxidation state to enable reliable endpoint detection, allowing the CMP process to stop precisely when the planarization layer is fully removed and the work function layer is exposed, preventing both pattern loading effects and damage to underlying layers.
Solution Approach 2:
The patent implements feedback through an in-situ endpoint detection system that monitors the CMP process in real-time. The system uses optical or electrical signals to detect when the planarization layer has been completely removed and the work function layer is exposed. This feedback signal automatically triggers the cessation of the CMP process, ensuring precise stopping at the end-point layer and preventing harmful over-polishing effects.
2Reliability
If CMP process continues to ensure complete removal of planarization layer, then material removal is thorough, but over-polishing occurs causing damage to underlying layers
Solution Approach 1:
The patent implements feedback through an in-situ endpoint detection system that monitors the CMP process in real-time. The system uses optical or electrical signals to detect when the planarization layer has been completely removed and the work function layer is exposed. This feedback signal automatically triggers the cessation of the CMP process, ensuring precise stopping at the end-point layer and preventing harmful over-polishing effects.
Solution Approach 2:
The patent applies preliminary action by forming an oxidized surface layer on the work function layer before the CMP process. This oxidized layer serves as a sacrificial endpoint indicator that can be detected during polishing. The layer is prepared in advance with specific thickness and oxidation state to enable reliable endpoint detection, allowing the CMP process to stop precisely when the planarization layer is fully removed and the work function layer is exposed, preventing both pattern loading effects and damage to underlying layers.
3Object-affected harmful factors
If CMP process stops early to prevent damage to underlying layers, then harmful factors are reduced, but planarization layer may not be completely removed
Solution Approach 1:
The patent applies preliminary action by forming an oxidized surface layer on the work function layer before the CMP process. This oxidized layer serves as a sacrificial endpoint indicator that can be detected during polishing. The layer is prepared in advance with specific thickness and oxidation state to enable reliable endpoint detection, allowing the CMP process to stop precisely when the planarization layer is fully removed and the work function layer is exposed, preventing both pattern loading effects and damage to underlying layers.
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
The system effectively stops the CMP process at the intended end-point layer, reducing pattern loading effects and preventing damage to underlying layers, thereby enhancing the precision and reliability of the wafer polishing process.
Implementation Method 1
A CMP system incorporating a light source and detector to provide incident light with photon energy greater than the band gap energy of the end-point layer, allowing for absorption detection
Data Source
AI summary
A chemical-mechanical planarization (CMP) system includes a platen, a pad, a polish head, a rotating mechanism, a light source, and a detector. The pad is disposed on the platen. The polish head is configured to hold a wafer against the pad. The rotating mechanism is configured to rotate at least one of the platen and the polish head. The light source is configured to provide incident light to an end-point layer on the wafer. The detector is configured to detect absorption of the incident light by the end-point layer.