CMP Pad Wear Modeling for Uniform Planarization Control
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) processes face challenges in accurately predicting and controlling polishing pad wear, leading to uneven planarization and reduced polishing rates due to glazing and non-uniform wear patterns, which are exacerbated by variations in incoming pad tolerance, wear rate, and tool-to-tool differences.
Innovation Solution
A method and system for modeling and controlling pad wear by using a pad wear removal model based on dwell times and total cut times, combined with displacement sensors and advanced algorithms like Kalman filters, to optimize pad conditioning and extend polishing pad life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP processes are used with regular pad replacement, then polishing rate is maintained, but pad life is reduced and process variability increases
Solution Approach 1:
The system performs preliminary characterization of the polishing pad's incoming profile and establishes a wear model before actual polishing begins. This allows prediction of pad wear throughout its life, enabling optimized conditioning schedules that extend pad life while maintaining polishing rate, rather than relying on conservative regular replacement
Solution Approach 2:
The system implements continuous feedback by measuring the pad's actual wear profile during use, comparing it to the predicted wear model, and adjusting the conditioning process parameters accordingly. This closed-loop control allows the pad to be used until its actual performance degrades, maximizing pad life while maintaining consistent polishing rate
2Reliability
If conservative pad life determination is used, then process reliability is improved, but pad usage efficiency is reduced
Solution Approach 1:
The system continuously monitors pad wear against the predicted model and provides feedback to adjust conditioning parameters. This allows the process to maintain reliability by detecting when pad performance degrades, while simultaneously maximizing pad usage by extending service life beyond conservative estimates through data-driven decision making
Solution Approach 2:
The system changes operating parameters (conditioning downforce, dwell time, speed) based on the pad's actual wear state and predicted remaining life. This dynamic parameter adjustment maintains process reliability by adapting to pad degradation, while improving productivity by optimizing conditions to extend usable pad life
3Ease of operation
If uniform conditioning is applied across the pad surface, then ease of operation is improved, but manufacturing precision deteriorates due to non-uniform wear patterns
Solution Approach 1:
The system divides the pad surface into multiple radial zones and applies different conditioning parameters to each zone based on its specific wear characteristics. This segmented approach addresses non-uniform wear patterns by tailoring conditioning to each region, improving planarization uniformity while maintaining operational simplicity through automated zone-based control
Solution Approach 2:
The system applies locally optimized conditioning parameters to different regions of the pad based on their specific wear states and functional requirements. This local quality approach ensures that each zone receives the appropriate conditioning intensity to maintain uniform planarization, while the automated system keeps operation simple
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 method improves polishing process results by providing accurate predictions of pad wear, enabling more efficient and uniform substrate planarization, thereby maximizing polishing pad life and maintaining consistent polishing performance.
Implementation Method 1
Typical pad conditioners include an abrasive head generally embedded with diamond abrasives which can be rubbed against the pad surface of the glazed polishing pad to retexture the pad
Implementation Method 2
the surface of the polishing pad becomes 'glazed' due to heat generated by friction between the surface of the substrate and the surface of the polishing pad during polishing
Data Source
AI summary
In one embodiment, a method is provided for polishing a substrate. The method generally includes receiving a plurality of dwell times of a pad conditioning disk, wherein the plurality of dwell times are to be used in a pad conditioning process performed on a pad disposed on a platen, and each dwell time corresponding to a zone of a plurality of zones of the pad disposed on the platen, determining a plurality of total pad conditioning disk cut times to be used in the pad conditioning process, each total pad conditioning disk cut time corresponding to a zone of the plurality of zones, and generating a first pad wear removal model based on a set of parameters, including the plurality of dwell times and the plurality of total pad conditioning disk cut times.