UBM Etch Endpoint Detection for Undercut Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor etching, the challenge lies in minimizing undercut during the etch process, particularly for smaller substrates, where existing methods result in significant lateral etching, reducing electrical performance and adhesion, and require excessive over-etching due to lack of precise control and endpoint detection.
Innovation Solution
A system utilizing a light detector, such as a CMOS or CCD camera, connected to a computing device for real-time endpoint detection, which captures and analyzes light reflections to determine etch completion, allowing for precise control of etch parameters and reduction of undercut by using multiple samples and increasing frame capture speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large over-etch is employed to ensure complete field metal removal, then reliability is improved, but manufacturing precision deteriorates due to increased undercut
Solution Approach 1:
The patent implements real-time optical monitoring during the etch process to detect the endpoint when field metal is completely removed. The system uses a light source and detector to monitor reflectivity changes, providing feedback that allows precise termination of the etch process, eliminating the need for large over-etch margins while ensuring complete field metal removal.
Solution Approach 2:
The patent dynamically adjusts etch parameters based on real-time process monitoring. By changing etch power, gas flow rates, or etchant concentration during the process based on detected endpoint signals, the system optimizes the balance between complete field metal removal and minimizing undercut, allowing precise control without excessive over-etch.
2Productivity
If batch processing is used to increase productivity, then productivity is improved, but manufacturing precision deteriorates due to poor etch uniformity
Solution Approach 1:
The patent divides the batch processing into individually monitored segments, with each wafer or wafer group equipped with independent optical monitoring. This allows real-time detection of etch endpoint for each segment, enabling precise control of etch uniformity across multiple wafers while maintaining batch processing productivity.
Solution Approach 2:
The system implements real-time optical feedback monitoring during batch etching, detecting endpoint conditions for each wafer or wafer group. This feedback mechanism allows the system to maintain consistent etch uniformity across the batch by identifying and responding to process variations, ensuring precise field metal removal without requiring excessive over-etch for all wafers.
3Adaptability or versatility
If feature sizes are reduced to enable smaller devices, then adaptability is improved, but manufacturing precision deteriorates due to increased relative undercut
Solution Approach 1:
The patent employs real-time optical endpoint detection that is particularly effective for small features, monitoring reflectivity changes with high sensitivity. This allows precise termination of the etch process for miniaturized devices, ensuring complete field metal removal while minimizing undercut impact on small bump and pillar structures, thereby maintaining manufacturing precision despite reduced feature sizes.
Solution Approach 2:
The system adjusts etch parameters dynamically based on real-time monitoring, optimizing the etch profile for small features. By controlling etch rate, selectivity, and endpoint detection sensitivity, the system minimizes lateral undercut while ensuring complete field metal removal, enabling safe reduction of device feature sizes without compromising structural integrity.
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 effectively minimizes undercut and eliminates incomplete etching, enabling more accurate and efficient etching processes, particularly for smaller substrates, by ensuring precise etch termination and adjusting parameters based on previous etch data.
Implementation Method 1
A system utilizes a light detector, such as a CMOS or CCD camera, connected to a computing device for real-time endpoint detection, which captures and analyzes light reflections to determine etch completion
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A semiconductor etch process is provided in which an undercut is minimized during an etch process through tight control of etch profile, recognition of etch completion, and minimization of over etch time to increase productivity.