Chamber Cleaning Method for Cu-to-Cu Bonding
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Solution Overview
Problem
In semiconductor manufacturing, the integration and productivity of wafer-to-wafer bonding processes are hindered by copper contamination in substrate processing chambers, which can lead to defects in subsequent wafer processing due to unremoved copper particles.
Innovation Solution
A chamber cleaning method utilizing plasma treatments with specific gases to form and remove copper oxide, coupled with real-time monitoring of copper contamination using optical diagnostic methods like OES, ensures efficient management of copper contamination by setting reference values for optimal cleaning cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma treatment with oxidizing gas is used to remove copper contamination, then copper removal effectiveness is improved, but chamber wall copper oxide accumulation increases
Solution Approach 1:
The cleaning process alternates between oxidizing plasma treatment (using CF4 gas to form copper oxide) and reducing plasma treatment (using H2 or He gas to remove copper oxide). This periodic switching between oxidation and reduction phases allows the system to remove copper contamination effectively while preventing excessive copper oxide accumulation on chamber walls by periodically removing it in the reduction phase.
Solution Approach 2:
The process changes gas composition parameters between two distinct phases: first introducing CF4 (carbon tetrafluoride) gas to create oxidizing plasma that converts copper to copper oxide, then switching to H2 (hydrogen) or He (helium) gas to create reducing plasma that removes the copper oxide. This parameter change in gas composition enables controlled cyclic cleaning that addresses both copper removal and chamber wall maintenance.
2Reliability
If frequent chamber cleaning is performed to maintain low copper contamination, then wafer processing reliability is improved, but production time and productivity are reduced
Solution Approach 1:
The system incorporates real-time monitoring of copper contamination levels in the chamber using optical emission spectroscopy (OES) or other diagnostic methods. When the monitored copper level reaches a predetermined threshold, the cyclic cleaning process is automatically triggered. This feedback mechanism ensures cleaning is performed only when necessary, maintaining wafer processing reliability while minimizing interruptions to production and maximizing productivity.
3Ease of operation
If conventional cleaning methods are used without real-time monitoring, then process simplicity is maintained, but copper contamination management precision deteriorates
Solution Approach 1:
Real-time monitoring of copper contamination levels using optical emission spectroscopy provides precise measurement of copper particle concentrations in the chamber. This feedback information enables automated control of the cyclic cleaning process, triggering cleaning operations at optimal moments based on actual contamination levels rather than fixed schedules. The system maintains ease of operation through automation while achieving high precision in copper contamination management.
Solution Approach 2:
The system replaces manual inspection and decision-making with automated optical monitoring and control. Optical emission spectroscopy detects copper contamination levels non-invasively and in real-time, substituting for complex manual sampling and analysis procedures. This substitution maintains operational simplicity while dramatically improving measurement precision and enabling data-driven cleaning decisions.
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 method effectively reduces copper contamination, allowing for reliable and efficient processing of wafers in semiconductor devices by continuously monitoring and managing copper levels, thereby preventing defects and ensuring high integration and productivity in wafer bonding processes.
Implementation Method 1
forming copper oxide on an inner wall of the chamber by oxidizing copper in the chamber by a plasma treatment that uses a first gas
Implementation Method 2
removing copper oxide by a plasma treatment that uses a second gas
Implementation Method 3
monitoring a copper contamination state in the chamber using optical emission spectroscopy (OES)
Data Source
AI summary
A chamber cleaning method includes processing a wafer for a Cu-to-Cu bonding process using plasma in a chamber; and removing copper from the chamber. Removing copper includes forming copper oxide on an inner wall of the chamber by oxidizing copper in the chamber by a plasma treatment that uses a first gas, performing a first monitoring operation that monitors a copper contamination state in the chamber using an optical diagnostic method, removing the copper oxide by a plasma treatment that uses a second gas; and performing a second monitoring operation that monitors a copper contamination state in the chamber using the optical diagnostic method.